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Showing papers in "Cancer Research in 2000"


Journal Article
TL;DR: Using a dosing schedule of cyclophosphamide that provided more sustained apoptosis of endothelial cells within the vascular bed of a tumor, it is shown that a chemotherapeutic agent can more effectively control tumor growth in mice, regardless of whether the tumor cells are drug resistant.
Abstract: To reveal the antiangiogenic capability of cancer chemotherapy, we developed an alternative antiangiogenic schedule for administration of cyclophosphamide. We show here that this antiangiogenic schedule avoided drug resistance and eradicated Lewis lung carcinoma and L1210 leukemia, an outcome not possible with the conventional schedule. When Lewis lung carcinoma and EMT-6 breast cancer were made drug resistant before therapy, the antiangiogenic schedule suppressed tumor growth 3-fold more effectively than the conventional schedule. When another angiogenesis inhibitor, TNP-470, was added to the antiangiogenic schedule of cyclophosphamide, drug-resistant Lewis lung carcinomas were eradicated. Each dose of the antiangiogenic schedule of cyclophosphamide induced the apoptosis of endothelial cells within tumors, and endothelial cell apoptosis preceded the apoptosis of drug-resistant tumor cells. This antiangiogenic effect was more pronounced in p53-null mice in which the apoptosis of p53-null endothelial cells induced by cyclophosphamide was so vigorous that drug-resistant tumors comprising 4.5% of body weight were eradicated. Thus, by using a dosing schedule of cyclophosphamide that provided more sustained apoptosis of endothelial cells within the vascular bed of a tumor, we show that a chemotherapeutic agent can more effectively control tumor growth in mice, regardless of whether the tumor cells are drug resistant.

1,541 citations


Journal Article
TL;DR: It is demonstrated that in human prostate cancer cells, basal-, growth factor- and mitogen-induced expression of hypoxia-inducible factor 1 (HIF-1) alpha, the regulated subunit of the transcription factor Hif-1, is blocked by LY294002 and rapamycin, inhibitors of PI3K and FRAP, respectively.
Abstract: Dysregulated signal transduction from receptor tyrosine kinases to phosphatidylinositol 3-kinase (PI3K), AKT (protein kinase B), and its effector FKBP-rapamycin-associated protein (FRAP) occurs via autocrine stimulation or inactivation of the tumor suppressor PTEN in many cancers. Here we demonstrate that in human prostate cancer cells, basal-, growth factor-, and mitogen-induced expression of hypoxia-inducible factor 1 (HIF-1) alpha, the regulated subunit of the transcription factor HIF-1, is blocked by LY294002 and rapamycin, inhibitors of PI3K and FRAP, respectively. HIF-1-dependent gene transcription is blocked by dominant-negative AKT or PI3K and by wild-type PTEN, whereas transcription is stimulated by constitutively active AKT or dominant-negative PTEN. LY294002 and rapamycin also inhibit growth factor- and mitogen-induced secretion of vascular endothelial growth factor, the product of a known HIF-1 target gene, thus linking the PI3K/PTEN/AKT/FRAP pathway, HIF-1, and tumor angiogenesis. These data indicate that pharmacological agents that target PI3K, AKT, or FRAP in tumor cells inhibit HIF-1alpha expression and that such inhibition may contribute to therapeutic efficacy.

1,487 citations


Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate that fibroblasts associated with carcinomas stimulate tumor progression of initiated nontumorigenic epithelial cells both in an in vivo tissue recombination system and in vitro coculture system.
Abstract: The present study demonstrates that fibroblasts associated with carcinomas stimulate tumor progression of initiated nontumorigenic epithelial cells both in an in vivo tissue recombination system and in an in vitro coculture system. Human prostatic carcinoma-associated fibroblasts grown with initiated human prostatic epithelial cells dramatically stimulated growth and altered histology of the epithelial population. This effect was not detected when normal prostatic fibroblasts were grown with the initiated epithelial cells under the same experimental conditions. In contrast, carcinoma-associated fibroblasts did not affect growth of normal human prostatic epithelial cells under identical conditions. From these data, we conclude that in this human prostate cancer model, carcinoma-associated fibroblasts stimulate progression of tumorigenesis. Thus, carcinoma-associated fibroblasts can direct tumor progression of an initiated prostate epithelial cell.

1,486 citations


Journal Article
TL;DR: Evidence that cyclooxygenase (COX)-2-derived prostaglandins contribute to tumor growth by inducing newly formed blood vessels (neoangiogenesis) that sustain tumor cell viability and growth and a novel application of this anti-inflammatory drug in the treatment of human cancer is provided.
Abstract: We provide evidence that cyclooxygenase (COX)-2-derived prostaglandins contribute to tumor growth by inducing newly formed blood vessels (neoangiogenesis) that sustain tumor cell viability and growth. COX-2 is expressed within human tumor neovasculature as well as in neoplastic cells present in human colon, breast, prostate, and lung cancer biopsy tissue. COX-1 is broadly distributed in normal, as well as in neoplastic, tissues. The contribution of COX-2 to human tumor growth was indicated by the ability of celecoxib, an agent that inhibits the COX-2 enzyme, to suppress growth of lung and colon tumors implanted into recipient mice. Mechanistically, celecoxib demonstrated a potent antiangiogenic activity. In a rat model of angiogenesis, we observe that corneal blood vessel formation is suppressed by celecoxib, but not by a COX-1 inhibitor. These and other data indicate that COX-2 and COX-2-derived prostaglandins may play a major role in development of cancer through numerous biochemical mechanisms, including stimulation of tumor cell growth and neovascularization. The ability of celecoxib to block angiogenesis and suppress tumor growth suggests a novel application of this anti-inflammatory drug in the treatment of human cancer.

1,320 citations


Journal Article
TL;DR: Lesions in the p16--cyclin D-CDK4--Rb and ARF--Mdm2--p53 pathways occur so frequently in cancer, regardless of patient age or tumor type, that they appear to be part of the life history of most, if not all, cancer cells.
Abstract: Genetic lesions that disable key regulators of G1 phase progression in mammalian cells are present in most human cancers. Mitogen-dependent, cyclin D-dependent kinases (cdk4 and cdk6) phosphorylate the retinoblastoma (Rb) tumor suppressor protein, helping to cancel its growth-inhibitory effects and enabling E2F transcription factors to activate genes required for entry into the DNA synthetic phase (S) of the cell division cycle. Among the E2F-responsive genes are cyclins E and A, which combine with and activate cdk2 to facilitate S phase entry and progression. Accumulation of cyclin D-dependent kinases during G1 phase sequesters cdk2 inhibitors of the Cip/Kip family, complementing the effects of the E2F transcriptional program by facilitating cyclin E-cdk2 activation at the G1-S transition. Disruption of "the Rb pathway" results from direct mutational inactivation of Rb function, by overexpression of cyclin D-dependent kinases, or through loss of p16(INK4a), an inhibitor of the cyclin D-dependent kinases. Reduction in levels of p27(Kip1) and increased expression of cyclin E also occur and carry a poor prognostic significance in many common forms of cancer. The ARF tumor suppressor, encoded by an alternative reading frame of the INK4a-ARF locus, senses "mitogenic current" flowing through the Rb pathway and is induced by abnormal growth promoting signals. By antagonizing Mdm2, a negative regulator of the p53 tumor suppressor, ARF triggers a p53-dependent transcriptional response that diverts incipient cancer cells to undergo growth arrest or apoptosis. Although ARF is not directly activated by signals that damage DNA, its loss not only dampens the p53 response to abnormal mitogenic signals but also renders tumor cells resistant to treatment by cytotoxic drugs and irradiation. Lesions in the p16--cyclin D-CDK4--Rb and ARF--Mdm2--p53 pathways occur so frequently in cancer, regardless of patient age or tumor type, that they appear to be part of the life history of most, if not all, cancer cells.

1,266 citations


Journal Article
TL;DR: A new class of HIF-1-responsive gene is defined, the activation of which has implications for the understanding of hypoxic tumor metabolism and which may provide endogenous markers for tumor hypoxia.
Abstract: The transcriptional complex hypoxia-inducible factor-1 (HIF-1) has emerged as an important mediator of gene expression patterns in tumors, although the range of responding genes is still incompletely defined. Here we show that the tumor-associated carbonic anhydrases (CAs) are tightly regulated by this system. Both CA9 and CA12 were strongly induced by hypoxia in a range of tumor cell lines. In renal carcinoma cells that are defective for the von Hippel-Lindau (VHL) tumor suppressor, up-regulation of these CAs is associated with loss of regulation by hypoxia, consistent with the critical function of pVHL in the regulation of HIF-1. Further studies of CA9 defined a HIF-1-dependent hypoxia response element in the minimal promoter and demonstrated that tight regulation by the HIF/pVHL system was reflected in the pattern of CA IX expression within tumors. Generalized up-regulation of CA IX in VHL-associated renal cell carcinoma contrasted with focal perinecrotic expression in a variety of non-VHL-associated tumors. In comparison with vascular endothelial growth factor mRNA, expression of CA IX demonstrated a similar, although more tightly circumscribed, pattern of expression around regions of necrosis and showed substantial although incomplete overlap with activation of the hypoxia marker pimonidazole. These studies define a new class of HIF-1-responsive gene, the activation of which has implications for the understanding of hypoxic tumor metabolism and which may provide endogenous markers for tumor hypoxia.

1,253 citations


Journal Article
TL;DR: It is concluded that collagen influences the tissue resistance to macromolecule transport, possibly by binding and stabilizing the glycosaminoglycan component of the ECM.
Abstract: The extracellular matrix (ECM) may contribute to the drug resistance of a solid tumor by preventing the penetration of therapeutic agents. We measured differences in interstitial resistance to macromolecule (IgG) motion in four tumor types and found an unexpected correspondence between transport resistance and the mechanical stiffness. The interstitial diffusion coefficient of IgG was measured in situ by fluorescence redistribution after photobleaching. Tissue elastic modulus and hydraulic conductivity were measured by confined compression of excised tissue. In apparent contradiction to an existing paradigm, these functional properties are correlated with total tissue content of collagen, not glycosaminoglycan. An extended collagen network was observed in the more penetration-resistant tumors. Collagenase treatment of the more penetration-resistant tumors significantly increased the IgG interstitial diffusion rate. We conclude that collagen influences the tissue resistance to macromolecule transport, possibly by binding and stabilizing the glycosaminoglycan component of the ECM. These findings suggest a new method to screen tumors for potential resistance to macromolecule-based therapy. Moreover, collagen and collagen-proteoglycan bonds are identified as potential targets of treatment to improve macromolecule delivery.

1,108 citations


Journal Article
TL;DR: It is shown here that the receptor for the NGR peptides in tumor vasculature is aminopeptidase N (APN; also called CD13), and APN is involved in angiogenesis and can serve as a target for delivering drugs into tumors and for inhibitingAngiogenesis.
Abstract: Phage that display a surface peptide with the NGR sequence motif home selectively to tumor vasculature in vivo. A drug coupled to an NGR peptide has more potent antitumor effects than the free drug [W. Arap et al., Science (Washington DC), 279: 377-380, 1998]. We show here that the receptor for the NGR peptides in tumor vasculature is aminopeptidase N (APN; also called CD13). NGR phage specifically bound to immunocaptured APN and to cells engineered to express APN on their surface. Antibodies against APN inhibited in vivo tumor homing by the NGR phage. Immunohistochemical staining showed that APN expression is up-regulated in endothelial cells within mouse and human tumors. In another tissue that undergoes angiogenesis, corpus luteum, blood vessels also expressed APN, but APN was not detected in blood vessels of various other normal tissues stained under the same conditions. APN antagonists specifically inhibited angiogenesis in chorioallantoic membranes and in the retina and suppressed tumor growth. Thus, APN is involved in angiogenesis and can serve as a target for delivering drugs into tumors and for inhibiting angiogenesis.

911 citations


Journal Article
TL;DR: A novel compound with therapeutic potential for the treatment of solid tumors and other diseases where angiogenesis plays an important role, PTK787/ZK 222584 is very well tolerated and does not impair wound healing.
Abstract: PTK787/ZK 222584 (1-[4-chloroanilino]-4-[4-pyridylmethyl] phthalazine succinate) is a potent inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinases, active in the submicromolar range. It also inhibits other class III kinases, such as the platelet-derived growth factor (PDGF) receptor beta tyrosine kinase, c-Kit, and c-Fms, but at higher concentrations. It is not active against kinases from other receptor families, such as epidermal growth factor receptor, fibroblast growth factor receptor-1, c-Met, and Tie-2, or intracellular kinases such as c-Src, c-Abl, and protein kinase C-alpha. PTK787/ZK 222584 inhibits VEGF-induced autophosphorylation of kinase insert domain-containing receptor (KDR), endothelial cell proliferation, migration, and survival in the nanomolar range in cell-based assays. In concentrations up to 1 microM, PTK787/ZK 222584 does not have any cytotoxic or antiproliferative effect on cells that do not express VEGF receptors. After oral dosing (50 mg/kg) to mice, plasma concentrations of PTK787/ZK 222584 remain above 1 microM for more than 8 h. PTK787/ZK 222584 induces dose-dependent inhibition of VEGF and PDGF-induced angiogenesis in a growth factor implant model, as well as a tumor cell-driven angiogenesis model after once-daily oral dosing (25-100 mg/kg). In the same dose range, it also inhibits the growth of several human carcinomas, grown s.c. in nude mice, as well as a murine renal carcinoma and its metastases in a syngeneic, orthotopic model. Histological examination of tumors revealed inhibition of microvessel formation in the interior of the tumor. PTK787/ZK 222584 is very well tolerated and does not impair wound healing. It also does not have any significant effects on circulating blood cells or bone marrow leukocytes as a single agent or impair hematopoetic recovery after concomitant cytotoxic anti-cancer agent challenge. This novel compound has therapeutic potential for the treatment of solid tumors and other diseases where angiogenesis plays an important role.

910 citations


Journal Article
TL;DR: This "magnetic drug targeting" offers a unique opportunity to treat malignant tumors locoregionally without systemic toxicity and may be possible to use these magnetic particles as a "carrier system" for a variety of anticancer agents, e.g., radionuclides, cancer-specific antibodies, and genes.
Abstract: The specific delivery of chemotherapeutic agents to their desired targets with a minimum of systemic side effects is an important, ongoing challenge of chemotherapy. One approach, developed in the past to address this problem, is the i.v. injection of magnetic particles[ ferrofluids (FFs)] bound to anticancer agents that are then concentrated in the desired area ( e.g., the tumor) by an external magnetic field. In the present study, we treated squamous cell carcinoma in rabbits with FFs bound to mitoxantrone (FF-MTX) that was concentrated with a magnetic field. Experimental VX-2 squamous cell carcinoma was implanted in the median portion of the hind limb of New Zealand White rabbits ( n = 26). When the tumor had reached a volume of ∼3500 mm 3 , FF-MTX was injected intraarterially (i.a.; femoral artery) or i.v. (ear vein), whereas an external magnetic field was focused on the tumor. FF-MTX i.a. application with the external magnetic field resulted in a significant ( P < 0.05), complete, and permanent remission of the squamous cell carcinoma compared with the control group (no treatment) and the i.v. FF-MTX group, with no signs of toxicity. The intratumoral accumulation of FFs was visualized both histologically and by magnetic resonance imaging. Thus, our data show that i.a. application of FF-MTX is successful in treating experimental squamous cell carcinoma. This “magnetic drug targeting” offers a unique opportunity to treat malignant tumors locoregionally without systemic toxicity. Furthermore, it may be possible to use these magnetic particles as a “carrier system” for a variety of anticancer agents, e.g., radionuclides, cancer-specific antibodies, and genes.

900 citations


Journal Article
TL;DR: It is demonstrated that aberrant methylation of the p16 and/or O6-methyl-guanine-DNA methyltransferase promoters can be detected in DNA from sputum in 100% of patients with squamous cell lung carcinoma up to 3 years before clinical diagnosis.
Abstract: Despite the promise of using DNA markers for the early detection of cancer, none has proven universally applicable to the most common and lethal forms of human malignancy. Lung carcinoma, the leading cause of tumor-related death, is a key example of a cancer for which mortality could be greatly reduced through the development of sensitive molecular markers detectable at the earliest stages of disease. By increasing the sensitivity of a PCR approach to detect methylated DNA sequences, we now demonstrate that aberrant methylation of the p16 and/or O6-methyl-guanine-DNA methyltransferase promoters can be detected in DNA from sputum in 100% of patients with squamous cell lung carcinoma up to 3 years before clinical diagnosis. Moreover, the prevalence of these markers in sputum from cancer-free, high-risk subjects approximates lifetime risk for lung cancer. The use of aberrant gene methylation as a molecular marker system seems to offer a potentially powerful approach to population-based screening for the detection of lung cancer, and possibly the other common forms of human cancer.

Journal Article
TL;DR: It is suggested that determination of the UGT1A1 genotypes might be clinically useful for predicting severe toxicity by irinotecan in cancer patients and warrants a prospective trial to corroborate the usefulness of gene diagnosis of UGT2A1 polymorphisms prior tb irinOTecan chemotherapy.
Abstract: Irinotecan unexpectedly causes severe toxicity of leukopenia or diarrhea. Irinotecan is metabolized to form active SN-38, which is further conjugated and detoxified by UDP-glucuronosyltransferase (UGT) 1A1 enzyme. Genetic polymorphisms of the UGT1A1 would affect an interindividual variation of the toxicity by irinotecan via the alternation of bioavailability of SN-38. In this case-control study, retrospective review of clinical records and determination of UGT1A1 polymorphisms were performed to investigate whether a patient with the variant UGT1A1 genotypes would be at higher risk for severe toxicity by irinotecan. All patients previously received irinotecan against cancer in university hospitals, cancer centers, or large urban hospitals in Japan. We identified 26 patients who experienced severe toxicity and 92 patients who did not. The relationship was studied between the multiple variant genotypes (UGT1A1*28 in the promoter and UGT1A1*6, UGT1A1*27, UGT1A1*29, and UGT1A1*7 in the coding region) and the severe toxicity of grade 4 leukopenia (< or =0.9 x 10(9)/liter) and/or grade 3 (watery for 5 days or more) or grade 4 (hemorrhagic or dehydration) diarrhea. Of the 26 patients with the severe toxicity, the genotypes of UGT1A1*28 were homozygous in 4 (15%) and heterozygous in 8 (31%), whereas 3 (3%) homozygous and 10 (11%) heterozygous were found among the 92 patients without the severe toxicity. Multivariate analysis suggested that the genotype either heterozygous or homozygous for UGT1A1*28 would be a significant risk factor for severe toxicity by irinotecan (P < 0.001; odds ratio, 7.23; 95% confidence interval, 2.52-22.3). All 3 patients heterozygous for UGT1A1*27 encountered severe toxicity. No statistical association of UGT1A1*6 with the occurrence of severe toxicity was observed. None had UGT1A1*29 or UGT1A1*7. We suggest that determination of the UGT1A1 genotypes might be clinically useful for predicting severe toxicity by irinotecan in cancer patients. This research warrants a prospective trial to corroborate the usefulness of gene diagnosis of UGT1A1 polymorphisms prior tb irinotecan chemotherapy.

Journal Article
TL;DR: Angiogenesis was found to be present in all tumors with characteristic and significant differences between the tumor types and there was a considerable degree of heterogeneity in the intensity of angiogenesis within each tumor group, as indicated by large standard deviations.
Abstract: Microvessel density (MVD) counting techniques have been widely used to assess the vasculature in tumors. MVD counts assess the presence of blood vessels but do not give an indication of the degree of angiogenesis and the functional status of the tumor neovasculature. To analyze angiogenesis and the functional status of the tumor vascular bed, we have quantitated endothelial cell proliferation and the recruitment of pericytes in human tumors [glioblastomas (n = 30), renal cell carcinomas (n = 22), colon carcinomas (n = 18), mammary carcinomas (n = 24), lung carcinomas (n = 15), and prostate carcinomas (n = 19)]. These findings were compared to the physiological angiogenesis in the cyclic bovine ovarian corpus luteum. Tissue sections were examined applying double-labeling immunohistochemical techniques to detect proliferating endothelial cells and to colocalize endothelial cells and pericytes. The following parameters were quantitated: (a) MVD count; (b) proliferating capillary index (PCI); (c) proliferating tumor versus endothelial cell index; and (d) microvessel pericyte coverage index (MPI). Based on endothelial cell proliferation, angiogenesis was found to be present in all tumors with characteristic and significant differences between the tumor types (glioblastomas, PCI = 9.6 +/- 6.1%; renal cell carcinomas, PCI = 9.4 +/- 5.2%; colon carcinomas, PCI = 7.8 +/- 5.2%; mammary carcinomas, PCI = 5.0 +/- 4.8%; lung carcinomas, PCI = 2.6 +/- 2.5%; prostate carcinomas, PCI = 2.0 +/- 1.4%). There was a considerable degree of heterogeneity in the intensity of angiogenesis within each tumor group, as indicated by large standard deviations. Even in the most angiogenic tumors, angiogenesis was found to be 4 to 20 times less intense as compared with the physiological angiogenesis in the growing ovarian corpus rubrum (PCI = 40.6 +/- 6.2%). Varying degrees of pericyte recruitment to the tumor microvasculature were determined in the different tumor types (glioblastomas, MPI = 12.7 +/- 7.9%; renal cell carcinomas, MPI = 17.9 +/- 7.8%; colon carcinomas, MPI = 65.4 +/- 10.5%; mammary carcinomas, MPI = 67.3 +/- 14.2%; lung carcinomas, MPI = 40.8 +/- 14.5%; prostate carcinomas, MPI = 29.6 +/- 9.5%). The data demonstrate distinct quantitative variations in the intensity of angiogenesis in malignant human tumors. Furthermore, the varying degrees of pericyte recruitment indicate differences in the functional status of the tumor vasculature in different tumors that may reflect varying degrees of maturation of the tumor vascular bed.

Journal Article
TL;DR: Endothelial cell signal transduction mechanisms involved in angiogenesis have come into focus in cancer research when it was realized that solid tumors are dependent on neovascularization.
Abstract: Endothelial cell signal transduction mechanisms involved in angiogenesis have come into focus in cancer research when it was realized that solid tumors are dependent on neovascularization [(1)][1] . Unlike normal human endothelial cells, which are quiescent except in the reproductive organs of

Journal Article
TL;DR: It is demonstrated that interleukin-3 stimulation induces a wortmannin-sensitive increase in mTOR kinase activity in a myeloid progenitor cell line, and that the activation status of the PI3K-AKT pathway in cancer cells may be an important determinant of cellular sensitivity to the cytostatic effect of rapamycin.
Abstract: The microbially derived antiproliferative agent rapamycin inhibits cell growth by interfering with the signaling functions of the mammalian target of rapamycin (mTOR). In this study, we demonstrate that interleukin-3 stimulation induces a wortmannin-sensitive increase in mTOR kinase activity in a myeloid progenitor cell line. The involvement of phosphoinositide 3'-kinase (PI3K) in the regulation of mTOR activity was further suggested by findings that mTOR was phosphorylated in vitro and in vivo by the PI3K-regulated protein kinase, AKT/PKB. Although AKT phosphorylated mTOR at two COOH-terminal sites (Thr2446 and Ser2448) in vitro, Ser2448 was the major phosphorylation site in insulin-stimulated or -activated AKT-expressing human embryonic kidney cells. Transient transfection assays with mTOR mutants bearing Ala substitutions at Ser2448 and/or Thr2446 indicated that AKT-dependent mTOR phosphorylation was not essential for either PHAS-I phosphorylation or p70S6K activation in HEK cells. However, a deletion of amino acids 2430-2450 in mTOR, which includes the potential AKT phosphorylation sites, significantly increased both the basal protein kinase activity and in vivo signaling functions of mTOR. These results demonstrate that mTOR is a direct target of the PI3K-AKT signaling pathway in mitogen-stimulated cells, and that the identified AKT phosphorylation sites are nested within a "repressor domain" that negatively regulates the catalytic activity of mTOR. Furthermore, the activation status of the PI3K-AKT pathway in cancer cells may be an important determinant of cellular sensitivity to the cytostatic effect of rapamycin.

Journal Article
TL;DR: The evidence from these experiments indicates that hypoxic response via Hif-1α is an important positive factor in solid tumor growth and that HIF-1 α affects tumor expansion in ways unrelated to its regulation of VEGF expression.
Abstract: Deficiencies in oxygenation are widespread in solid tumors. The transcription factor hypoxia-inducible factor (HIF)-1alpha is an important mediator of the hypoxic response of tumor cells and controls the up-regulation of a number of factors important for solid tumor expansion, including the angiogenic factor vascular endothelial growth factor (VEGF). We have isolated two cell lines nullizygous for HIF-1alpha, one from embryos genetically null for HIF-1alpha, and the other from embryos carrying loxP-flanked alleles of the gene, which allows for cre-mediated excision. The loss of HIF-1alpha negatively affects tumor growth in these two sets of H-ras-transformed cell lines, and this negative effect is not due to deficient vascularization. Despite differences in VEGF expression, vascular density is similar in wild-type and HIF-1alpha-null tumors. The evidence from these experiments indicates that hypoxic response via HIF-1alpha is an important positive factor in solid tumor growth and that HIF-1alpha affects tumor expansion in ways unrelated to its regulation of VEGF expression.

Journal Article
TL;DR: A new lipid formulation containing doxorubicin that has been optimized for both mild hyperthermic temperatures and rapid release times is described, found to be significantly more effective than free drug or current liposome formulations at reducing tumor growth in a human squamous cell carcinoma xenograft line.
Abstract: The single biggest challenge now facing drug delivery (for liposomes and indeed other carriers) is to initiate and produce release of the encapsulated drug only at the diseased site and at controllable rates. Our efforts have focused on developing a new thermal-sensitive drug delivery system, specifically for the local control of solid tumors. We describe here a new lipid formulation containing doxorubicin that has been optimized for both mild hyperthermic temperatures (39 degrees C to 40 degrees C) that are readily achievable in the clinic and rapid release times of drug (tens of seconds). This new liposome, in combination with mild hyperthermia, was found to be significantly more effective than free drug or current liposome formulations at reducing tumor growth in a human squamous cell carcinoma xenograft line (FaDu), producing 11 of 11 complete regressions lasting up to 60 days posttreatment.

Journal Article
TL;DR: It is concluded that tumor lactate content may be used as a prognostic parameter in the clinic and in accordance with data from the literature showing that the presence of hypoxia in cervical tumors is associated with a poorer patient survival.
Abstract: Pathophysiological parameters such as vascular density and tissue oxygen pressure can influence tumor malignancy and patient survival. Observations from our group showed that metastatic spread of carcinomas of the uterine cervix and of head and neck cancers was closely correlated with the lactate concentration in the primary lesion. Because these results were obtained in a low number of patients, the present investigation was performed to verify such a correlation in a larger population. Cryobiopsies were taken at first diagnosis of cervical cancer from 34 patients. Tissue concentrations of ATP, glucose, and lactate in viable tumor regions of these biopsies were measured microscopically using the technique of imaging bioluminescence. There was no correlation between stage or grade and any of the metabolic parameters measured. ATP and glucose concentrations were not significantly different in metastatic and nonmetastatic primary tumors (P>0.05). However, lactate concentrations were significantly higher (P = 0.001) in tumors with metastatic spread (mean +/- SD, 10.0+/-2.9 micromol/g; n = 20) compared with malignancies in patients without metastases (6.3+/-2.8 micromol/g; n = 14). The majority of patients who suffered a recurrence of the disease (17 of a total of 22 patients) or died (15 of 20) within the observation period of up to 8 years belonged to the metastatic, i.e., high lactate group. A Kaplan-Meier analysis of the data showed that the overall and disease-free survival probabilities of patients having low tumor lactate values were significantly higher compared with patients with high tumor lactate concentrations (P = 0.015 and 0.014, respectively). We conclude that tumor lactate content may be used as a prognostic parameter in the clinic. Furthermore, these findings are in accordance with data from the literature showing that the presence of hypoxia in cervical tumors is associated with a poorer patient survival.

Journal Article
TL;DR: Understanding the structure and functions of oncogenic p53 mutants may lead to more potent reactivation modalities or to the ability to eliminate mutant p53 gain of function.
Abstract: The p53 guardian of the genome is inactivated in the majority of cancers, mostly through missense mutations that cause single residue changes in the DNA binding core domain of the protein. Not only do such mutations result in the abrogation of wild-type p53 activity, but the expressed p53 mutant proteins also tend to gain oncogenic functions, such as interference with wild-type p53-independent apoptosis. Because p53 mutants are highly expressed in cancer cells and not in normal cells, their reactivation to wild-type p53 function may eliminate the cancer by apoptosis or another p53-dependent mechanism. Several studies that embarked on this quest for reactivation have succeeded in restoring wildtype p53 activity to several p53 mutants. However, mutants with more extensive structural changes in the DNA binding core domain may be refractory to reactivation to the wild-type p53 phenotype. Therefore, understanding the structure and functions of oncogenic p53 mutants may lead to more potent reactivation modalities or to the ability to eliminate mutant p53 gain of function.

Journal Article
TL;DR: The inhibition of the growth of U87 and LS174T tumors by the anti-VEGF mAb was associated with a significant reduction in tumor vascular density and a relatively small increase in the number of apoptotic cells.
Abstract: Recent studies in experimental animals have shown that combining antiangiogenic therapy with radiation can enhance tumor response. Whether this enhancement is mainly attributable to angiogenesis inhibition, endothelial cell radiosensitivity, tumor cell apoptosis, or a decrease in the number of hypoxic cells (improved oxygenation) is not known. We designed this study to discern the role of tumor oxygenation. We chose an anti-vascular endothelial growth factor (anti-VEGF) monoclonal antibody (mAb) which has a known target, human VEGF. We also measured interstitial fluid pressure (IFP) to test the hypothesis that the decreased vascular permeability induced by the anti-VEGF mAb can lower IFP. The effect of anti-VEGF mAb on vascular density, partial oxygen tension (pO2), and apoptosis was also measured. Athymic NCr/Sed nu/nu mice bearing 6-mm xenograft of the human glioblastoma multiforme (U87), or colon adenocarcinoma (LS174T) were treated with anti-VEGF mAb injected i.p. on alternate days for a total of six injections at a dosage of 100 microg/injection/mouse. For combined anti-VEGF and radiation, single radiation doses were given under normal blood flow (20 and 30 Gy) or clamped hypoxic conditions (30 and 40 Gy) 24 h after the sixth injection of mAb. The inhibition of the growth of U87 and LS174T tumors by the anti-VEGF mAb was associated with a significant reduction in tumor vascular density and a relatively small increase in the number of apoptotic cells. Compared with size-matched controls, IFP decreased by 74% in LS174T, and 73% in U87 in mice treated with anti-VEGF mAb. After antibody treatment PO2 increased significantly in U87, but did not change in LS174T tumors. Combined treatment induced in U87 tumors a tumor-growth delay (TGD) which was greater than additive; in LS174T except for the 40-Gy hypoxic group, the effect was only additive. In both U87 and LS174T the TGD induced by the antibody was independent of oxygen levels in the tumor at the time of radiation. The fact that the increase in TGD occurred under both normoxic and hypoxic conditions suggests that anti-VEGF mAb treatment can compensate for the resistance to radiation induced by hypoxia.

Journal Article
TL;DR: The determination of multiple EGFR mutations within individual tumors suggests that glioblastomas with EGFR amplification have the capacity to produce a variety of functionally distinct EGFRs.
Abstract: Several types of epidermal growth factor receptor (EGFR) gene mutations have been reported in glioblastomas, and in nearly all cases the alterations have been reported in tumors with EGFR amplification. The objectives of this study were to determine the frequency and diversity of EGFR mutations in glioblastomas and to determine whether gene mutation is inevitably associated with increased EGFR gene dosage. To accomplish these aims, we sequenced cDNA products representing the entire EGFR coding region in 44 glioblastomas, half of which had EGFR amplification. Coding sequence alterations were identified in 17 of the tumors, and each of these cases had amplified EGFR. No mutations were identified in the 22 tumors without EGFR amplification. An additional 26 glioblastomas with EGFR amplification were then examined to establish more reliable frequencies for each type of mutation identified in the tumors for which the entire gene was sequenced. Transcripts associated with the most common mutation lacked coding sequence for amino acids 6-273 (67%). This mutation has been described extensively in the literature. Transcripts encoding receptors that would truncate at amino acid 958 and transcripts encoding receptors that would lack amino acids 521-603 were the next most common types of alteration. Each of these were observed in 15% of the tumors with EGFR amplification. Other mutations were observed at lower frequencies, but among these were three cases with missense mutations. Sixteen of the 48 tumors with EGFR amplification showed multiple types of EGFR mutations (33%), and in one case it was determined that multiple alterations had occurred in the same transcript. In total, these data are consistent with EGFR mutation being exclusively and frequently associated with EGFR amplification. Furthermore, the determination of multiple EGFR mutations within individual tumors suggests that glioblastomas with EGFR amplification have the capacity to produce a variety of functionally distinct EGFRs.

Journal Article
TL;DR: The results suggest that hydroxamic acid-based hybrid polar compounds inhibit prostate cancer cell growth and may be useful, relatively nontoxic agents for the treatment of prostate carcinoma.
Abstract: Suberoylanilide hydroxamic acid (SAHA) is the prototype of a family of hybrid polar compounds that induce growth arrest in transformed cells and show promise for the treatment of cancer. SAHA induces differentiation and/or apoptosis in certain transformed cells in culture and is a potent inhibitor of histone deacetylases. In this study, we examined the effects of SAHA on the growth of human prostate cancer cells in culture and on the growth of the CWR22 human prostate xenograft in nude mice. SAHA suppressed the growth of the LNCaP, PC-3, and TSU-Pr1 cell lines at micromolar concentrations (2.5-7.5 microM). SAHA induced dose-dependent cell death in the LNCaP cells. In mice with transplanted CWR222 human prostate tumors, SAHA (25, 50, and 100 mg/kg/day) caused significant suppression of tumor growth compared with mice receiving vehicle alone; treatment with 50 mg/kg/day resulted in a 97% reduction in the mean final tumor volume compared with controls. At this dose, there was no detectable toxicity as evaluated by weight gain and necropsy examination. Increased accumulation of acetylated core histones was detected in the CWR22 tumors within 6 h of SAHA administration. SAHA induced prostate-specific antigen mRNA expression in CWR22 prostate cancer cells, resulting in higher levels of serum prostate-specific antigen than predicted from tumor volume alone. The results suggest that hydroxamic acid-based hybrid polar compounds inhibit prostate cancer cell growth and may be useful, relatively nontoxic agents for the treatment of prostate carcinoma.

Journal Article
TL;DR: Investigating the effect of hyperthermia (42 degrees C) on the extravasation of different sized nanoparticles from tumor microvasculature in a human tumor (SKOV-3 ovarian carcinoma) xenograft grown in mouse window chambers indicates thathyperthermia can enable and augment liposomal drug delivery to tumors and potentially help target liposomes specifically to tumors.
Abstract: The efficacy of novel cancer therapeutics has been hampered by the ability to deliver these agents to the tumor at effective concentrations. Liposomes have been used as a method to overcome some delivery issues and, in combination with hyperthermia, have been shown to increase drug delivery to tumors. Particle size has been shown to affect the delivery of liposomes, but it is not known how hyperthermia affects size dependence. This study investigates the effect of hyperthermia (42 degrees C) on the extravasation of different sized nanoparticles (albumin; 100-, 200-, and 400-nm liposomes) from tumor microvasculature in a human tumor (SKOV-3 ovarian carcinoma) xenograft grown in mouse window chambers. In this model (at 34 degrees C), no liposomes were able to extravasate into the tumor interstitium. Hyperthermia enabled liposome extravasation of all sizes. The magnitude of hyperthermia-induced extravasation was inversely proportional to particle size. Thus, at normothermia (34 degrees C), the pore cutoff size for this model was between 7 and 100 nm (e.g., liposomes did not extravasate). At 42 degrees C, the pore cutoff size was increased to >400 nm, allowing all nanoparticles tested to be delivered to the tumor interstitium to some degree. With hyperthermia, the 100-nm liposome experienced the largest relative increase in extravasation from tumor vasculature. Hyperthermia did not enable extravasation of 100-nm liposomes from normal vasculature, potentially allowing for tumor-specific delivery. These experiments indicate that hyperthermia can enable and augment liposomal drug delivery to tumors and potentially help target liposomes specifically to tumors.

Journal Article
TL;DR: The results strongly suggest that in addition to the activation of detoxifying enzymes, induction of apoptosis is also involved in the sulforaphane-associated chemoprevention of cancer.
Abstract: Sulforaphane is an isothiocyanate that is present naturally in widely consumed vegetables and has a particularly high concentration in broccoli. This compound has been shown to block the formation of tumors initiated by chemicals in the rat. Although sulforaphane has been proposed to modulate the metabolism of carcinogens, its mechanism of action remains poorly understood. We have previously demonstrated that sulforaphane inhibits the reinitiation of growth and decreases the cellular viability of quiescent human colon carcinoma cells (HT29). Moreover, the weak effect observed on differentiated CaCo2 cells suggests a specific anticancer activity for this compound. Here we investigated the effect of sulforaphane on the growth and viability of HT29 cells during their exponentially growing phase. We observed that sulforaphane induced a cell cycle arrest in a dose-dependent manner, followed by cell death. This sulforaphane-induced cell cycle arrest was correlated with an increased expression of cyclins A and B1. Moreover, we clearly demonstrated that sulforaphane induced cell death via an apoptotic process. Indeed, a large proportion of treated cells display the following: (a) translocation of phosphatidylserine from the inner layer to the outer layer of the plasma membrane; (b) typical chromatin condensation; and (c) ultrastructural modifications related to apoptotic cell death. We also showed that the expression of p53 was not changed in sulforaphane-treated cells. In contrast, whereas bcl-2 was not detected, we observed increased expression of the proapoptotic protein bax, the release of cytochrome c from the mitochondria to the cytosol, and the proteolytic cleavage of poly(ADP-ribose) polymerase. In conclusion, our results strongly suggest that in addition to the activation of detoxifying enzymes, induction of apoptosis is also involved in the sulforaphane-associated chemoprevention of cancer.

Journal Article
TL;DR: HIF-1alpha expression is a strong independent prognostic marker in early stage cervical cancer and its influence on prognosis in patients with cervical cancer stage pT1b is investigated using immunohistochemistry.
Abstract: Hypoxia-inducible factor 1alpha (HIF-1alpha) is a transcriptional factor that regulates genes involved in response to hypoxia and promotes neoangiogenesis, which are considered essential for tumor growth and progression. Using immunohistochemistry, we investigated the influence of HIF-1alpha expression on prognosis in 91 patients with cervical cancer stage pT1b. In univariate and multivariate analysis, patients with strong expression of HIF-1alpha had a significantly shorter overall survival time (P = 0.0307, log-rank test) and disease-free survival time (P < 0.0001, log-rank test) compared with those with moderate to absent HIF-1alpha expression. HIF-1alpha expression is a strong independent prognostic marker in early stage cervical cancer.

Journal Article
TL;DR: Evidence that BP pretreatment of breast and prostate carcinoma cells inhibited tumor cell invasion in a dose-dependent manner is provided and BPs may be useful agents for the prophylactic treatment of patients with cancers that are known to preferentially metastasize to bone is suggested.
Abstract: The molecular mechanisms by which tumor cells metastasize to bone are likely to involve invasion, cell adhesion to bone, and the release of soluble mediators from tumor cells that stimulate osteoclast-mediated bone resorption. Bisphosphonates (BPs) are powerful inhibitors of the osteoclast activity and are, therefore, used in the treatment of patients with osteolytic metastases. However, an added beneficial effect of BPs may be direct antitumor activity. We previously reported that BPs inhibit breast and prostate carcinoma cell adhesion to bone (Boissier et al., Cancer Res., 57: 3890-3894, 1997). Here, we provided evidence that BP pretreatment of breast and prostate carcinoma cells inhibited tumor cell invasion in a dose-dependent manner. The order of potency for four BPs in inhibiting tumor cell invasion was: zoledronate > ibandronate > NE-10244 (active pyridinium analogue of risedronate) > clodronate. In addition, NE-58051 (the inactive pyridylpropylidene analogue of risedronate) had no inhibitory effect, whereas NE-10790 (a phosphonocarboxylate analogue of risedronate in which one of the phosphonate groups is substituted by a carboxyl group) inhibited tumor cell invasion to an extent similar to that observed with NE-10244, indicating that the inhibitory activity of BPs on tumor cells involved the R2 chain of the molecule. BPs did not induce apoptosis in tumor cells, nor did they inhibit tumor cell migration at concentrations that did inhibit tumor cell invasion. However, although BPs did not interfere with the production of matrix metalloproteinases (MMPs) by tumor cells, they inhibited their proteolytic activity. The inhibitory effect of BPs on MMP activity was completely reversed in the presence of an excess of zinc. In addition, NE-10790 did not inhibit MMP activity, suggesting that phosphonate groups of BPs are responsible for the chelation of zinc and the subsequent inhibition of MMP activity. In conclusion, our results provide evidence for a direct cellular effect of BPs in preventing tumor cell invasion and an inhibitory effect of BPs on the proteolytic activity of MMPs through zinc chelation. These results suggest, therefore, that BPs may be useful agents for the prophylactic treatment of patients with cancers that are known to preferentially metastasize to bone.

Journal Article
TL;DR: Immunohistochemistry for the Dpc4 protein in formalin-fixed, paraffin-embedded tissue is a sensitive and specific marker for DPC4 gene status, providing a tool to examine D PC4 status in putative precursor lesions.
Abstract: Infiltrating adenocarcinomas of the pancreas are believed to arise from histologically identifiable intraductal precursors [pancreatic intraepithelial neoplasias (PanINs)] that undergo a series of architectural, cytological, and genetic changes. The role of DPC4 tumor suppressor gene inactivation in this progression has not been defined. Immunohistochemistry for the Dpc4 protein in formalin-fixed, paraffin-embedded tissue is a sensitive and specific marker for DPC4 gene status, providing a tool to examine DPC4 status in these putative precursor lesions. A total of 188 PanINs were identified in 40 pancreata, 38 (95%) of which also contained an infiltrating adenocarcinoma. Sections containing these 188 duct lesions were labeled with a monoclonal antibody to Dpc4. All 82 flat (PanIN-1A), all 54 papillary (PanIN-1B), and all 23 atypical papillary (PanIN-2) intraductal lesions expressed Dpc4. In contrast, 9 of 29 (31%) severely atypical lesions (PanIN-3 lesions, carcinomas in situ) did not. The difference in Dpc4 expression between histologically low-grade (PanIN-1 and -2) and histologically high-grade (PanIN-3) duct lesions was statistically significant (P < 0.0001). In three cases, the pattern of Dpc4 expression in the PanIN-3 lesions did not match the pattern of expression in the associated infiltrating carcinomas, indicating that these high-grade lesions did not simply represent infiltrating carcinoma growing along benign ducts. Loss of Dpc4 expression occurs biologically late in the neoplastic progression that leads to the development of infiltrating pancreatic cancer, at the stage of histologically recognizable carcinoma.

Journal Article
TL;DR: The basic methods of fractal geometry are outlined and the value and limitations of applying this new tool to cancer research are discussed.
Abstract: Recent studies have shown that fractal geometry, a vocabulary of irregular shapes, can be useful for describing the pathological architecture of tumors and, perhaps more surprisingly, for yielding insights into the mechanisms of tumor growth and angiogenesis that complement those obtained by modern molecular methods. This article outlines the basic methods of fractal geometry and discusses the value and limitations of applying this new tool to cancer research.

Journal Article
Thierry Soussi1
TL;DR: It is demonstrated that p53-Abs are found predominantly in human cancer patients with a specificity of 96%.
Abstract: p53 antibodies (p53-Abs) were discovered 20 years ago during the course of tumor-associated antigens screening. The discovery of p53 mutation and accumulation of p53 in human tumors shed new light on the p53 humoral response. In the present review, we have compiled more than 130 papers published in this specific field since 1992. We demonstrate that p53-Abs are found predominantly in human cancer patients with a specificity of 96%. Such antibodies are predominantly associated with p53 gene missense mutations and p53 accumulation in the tumor, but the sensitivity of such detection is only 30%. It has been demonstrated that this immune response is due to a self-immunization process linked to the strong immunogenicity of the p53 protein. The clinical value of these antibodies remains subject to debate, but consistent results have been observed in breast, colon, oral, and gastric cancers, in which they have been associated with high-grade tumors and poor survival. The finding of p53-Abs in the sera of individuals who are at high risk of cancer, such as exposed workers or heavy smokers, indicates that they have promising potential in the early detection of cancer.

Journal Article
TL;DR: The data indicate that activation of iNOS and excess production of NO in response to inflammatory cytokines cause DNA damage and inhibit DNA repair proteins and NO inactivation of DNA repair enzymes may provide a link between inflammation and the initiation, promotion, and/or progression of cholangiocarcinoma.
Abstract: Chronic infection and inflammation are risk factors for the development of cholangiocarcinoma, a highly malignant, generally fatal adenocarcinoma originating from biliary epithelia. However, the link between inflammation and carcinogenesis in these disorders is obscure. Because nitric oxide (NO) is generated in inflamed tissues by inducible nitric oxide synthase (iNOS) and because DNA repair proteins are potentially susceptible to NO-mediated nitrosylation, we formulated the hypothesis that inflammatory cytokines induce iNOS and sufficient NO to inhibit DNA repair enzymes leading to the development and progression of cholangiocarcinoma. iNOS and nitrotyrosine were demonstrated in 18/18 cholangiocarcinoma specimens. Furthermore, iNOS and NO generation could be induced in vitro by inflammatory cytokines (mixture of interleukin-1β, IFN-γ, and tumor necrosis factorα ) in three human cholangiocarcinoma cell lines. NO-dependent DNA damage as assessed by the comet assay was demonstrated during exposure of the three cholangiocarcinoma cell lines to cytokines. Moreover, global DNA repair activity was inhibited by 70% by a NO-dependent process after exposure of cells to cytokines. Our data indicate that activation of iNOS and excess production of NO in response to inflammatory cytokines cause DNA damage and inhibit DNA repair proteins. NO inactivation of DNA repair enzymes may provide a link between inflammation and the initiation, promotion, and/or progression of cholangiocarcinoma.