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Showing papers in "Cancer Research in 1999"


Journal Article
TL;DR: The first clinical data indicating that HIF-1alpha may play an important role in human cancer progression are provided, indicating adaptations to a hypoxic microenvironment that are correlated with tumor invasion, metastasis, and lethality.
Abstract: Neovascularization and increased glycolysis, two universal characteristics of solid tumors, represent adaptations to a hypoxic microenvironment that are correlated with tumor invasion, metastasis, and lethality. Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding glucose transporters, glycolytic enzymes, and vascular endothelial growth factor. HIF-1 transcriptional activity is determined by regulated expression of the HIF-1α subunit. In this study, HIF-1α expression was analyzed by immunohistochemistry in 179 tumor specimens. HIF-1α was overexpressed in 13 of 19 tumor types compared with the respective normal tissues, including colon, breast, gastric, lung, skin, ovarian, pancreatic, prostate, and renal carcinomas. HIF-1α expression was correlated with aberrant p53 accumulation and cell proliferation. Preneoplastic lesions in breast, colon, and prostate overexpressed HIF-1α, whereas benign tumors in breast and uterus did not. HIF-1α overexpression was detected in only 29% of primary breast cancers but in 69% of breast cancer metastases. In brain tumors, HIF-1α immunohistochemistry demarcated areas of angiogenesis. These results provide the first clinical data indicating that HIF-1α may play an important role in human cancer progression.

2,338 citations


Journal Article
TL;DR: The data show that inhibition of this target site by PS-341 results in reduced tumor growth in murine tumor models and highlight that the proteasome is a novel biochemical target and that inhibitors such asPS-341 represent a unique class of antitumor agents.
Abstract: The ubiquitin-proteasome pathway plays a critical role in the regulated degradation of proteins involved in cell cycle control and tumor growth. Dysregulating the degradation of such proteins should have profound effects on tumor growth and cause cells to undergo apoptosis. To test this hypothesis, we developed a novel series of proteasome inhibitors, exemplified by PS-341, which we describe here. As determined by the National Cancer Institute in vitro screen, PS-341 has substantial cytotoxicity against a broad range of human tumor cells, including prostate cancer cell lines. The PC-3 prostate cell line was, therefore, chosen to further examine the antitumor activity of PS-341. In vitro, PS-341 elicits proteasome inhibition, leading to an increase in the intracellular levels of specific proteins, including the cyclin-dependent kinase inhibitor, p21. Moreover, exposure of such cells to PS-341 caused them to accumulate in the G2-M phase of the cell cycle and subsequently undergo apoptosis, as indicated by nuclear condensation and poly(ADP-ribose) polymerase cleavage. Following weekly i.v. treatment of PS-341 to mice bearing the PC-3 tumor, a significant decrease (60%) in tumor burden was observed in vivo. Direct injection of PS-341 into the tumor also caused a substantial (70%) decrease in tumor volume with 40% of the drug-treated mice having no detectable tumors at the end of the study. Studies also revealed that i.v. administration of PS-341 resulted in a rapid and widespread distribution of PS-341, with highest levels identified in the liver and gastrointestinal tract and lowest levels in the skin and muscle. Modest levels were found in the prostate, whereas there was no apparent penetration of the central nervous system. An assay to follow the biological activity of the PS-341 was established and used to determine temporal drug activity as well as its ability to penetrate tissues. As such, PS-341 was shown to penetrate PC-3 tumors and inhibit intracellular proteasome activity 1.0 h after i.v. dosing. These data illustrate that PS-341 not only reaches its biological target but has a direct effect on its biochemical target, the proteasome. Importantly, the data show that inhibition of this target site by PS-341 results in reduced tumor growth in murine tumor models. Together, the results highlight that the proteasome is a novel biochemical target and that inhibitors such as PS-341 represent a unique class of antitumor agents. PS-341 is currently under clinical evaluation for advanced cancers.

1,502 citations


Journal Article
TL;DR: The presence of aberrant hypermethylation was associated with loss of MGMT protein, in contrast to retention of protein in the majority of tumors without aberrantHypermethylation, suggesting that epigenetic inactivation of MG MT plays an important role in primary human neoplasia.
Abstract: The DNA repair protein O6-methylguanine DNA methyltransferase (MGMT) removes alkyl adducts from the O6 position of guanine. MGMT expression is decreased in some tumor tissues, and lack of activity has been observed in some cell lines. Loss of expression is rarely due to deletion, mutation, or rearrangement of the MGMT gene, but methylation of discrete regions of the CpG island of MGMT has been associated with the silencing of the gene in cell lines. We used methylation-specific PCR to study the promoter methylation of the MGMT gene. All normal tissues and expressing cancer cell lines were unmethylated, whereas nonexpressing cancer cell lines were methylated. Among the more than 500 primary human tumors examined, MGMT hypermethylation was present in a subset of specific types of cancer. In gliomas and colorectal carcinomas, aberrant methylation was detected in 40% of the tumors, whereas in non-small cell lung carcinomas, lymphomas, and head and neck carcinomas, this alteration was found in 25% of the tumors. MGMT methylation was found rarely or not at all in other tumor types. We also analyzed MGMT expression by immunohistochemistry in relation to the methylation status in 31 primary tumors. The presence of aberrant hypermethylation was associated with loss of MGMT protein, in contrast to retention of protein in the majority of tumors without aberrant hypermethylation. Our results suggest that epigenetic inactivation of MGMT plays an important role in primary human neoplasia.

1,240 citations


Journal Article
TL;DR: Caffeine inhibits the catalytic activity of both ATM and the related kinase, ATM and Rad3-related (ATR), at drug concentrations similar to those that induce radiosensitization, suggesting that both proteins are relevant targets for the development of novel anticancer agents.
Abstract: Caffeine exposure sensitizes tumor cells to ionizing radiation and other genotoxic agents. The radiosensitizing effects of caffeine are associated with the disruption of multiple DNA damage-responsive cell cycle checkpoints. The similarity of these checkpoint defects to those seen in ataxia-telangiectasia (A-T) suggested that caffeine might inhibit one or more components in an A-T mutated (ATM)-dependent checkpoint pathway in DNA-damaged cells. We now show that caffeine inhibits the catalytic activity of both ATM and the related kinase, ATM and Rad3-related (ATR), at drug concentrations similar to those that induce radiosensitization. Moreover, like ATM-deficient cells, caffeine-treated A549 lung carcinoma cells irradiated in G2 fail to arrest progression into mitosis, and S-phase-irradiated cells exhibit radioresistant DNA synthesis. Similar concentrations of caffeine also inhibit gamma- and UV radiation-induced phosphorylation of p53 on Ser15, a modification that may be directly mediated by the ATM and ATR kinases. DNA-dependent protein kinase, another ATM-related protein involved in DNA damage repair, was resistant to the inhibitory effects of caffeine. Likewise, the catalytic activity of the G2 checkpoint kinase, hChk1, was only marginally suppressed by caffeine but was inhibited potently by the structurally distinct radiosensitizer, UCN-01. These data suggest that the radiosensitizing effects of caffeine are related to inhibition of the protein kinase activities of ATM and ATR and that both proteins are relevant targets for the development of novel anticancer agents.

1,121 citations


Journal Article
TL;DR: Kinetic analysis showed that the administration of anti-CD25 mAb (PC61) later than day 2 after tumor inoculation caused no tumor regression, irrespective of depletion of CD4+ CD25+ immunoregulatory cells.
Abstract: Immune regulation has been shown to be involved in the progressive growth of some murine tumors. In this study, we demonstrated that a single in vivo administration of an amount less than 0.125 mg of anti-CD25 interleukin 2 receptor a monoclonal antibody (mAb; PC61) caused the regression of tumors that grew progressively in syngeneic mice. The tumors used were five leukemias, a myeloma, and two sarcomas derived from four different inbred mouse strains. Anti-CD25 mAb (PC61) showed an effect in six of the eight tumors. Administration of anti-CD25 mAb (PC61) caused a reduction in the number of CD4 1 CD25 1 cells in the peripheral lymphoid tissues. The findings suggested that CD4 1 CD25 1 immunoregulatory cells were involved in the growth of those tumors. Kinetic analysis showed that the administration of anti-CD25 mAb (PC61) later than day 2 after tumor inoculation caused no tumor regression, irrespective of depletion of CD4 1 CD25 1 immunoregulatory cells. Two leukemias, on which the PC61-treatment had no effect, seemed to be incapable of eliciting effective rejection responses in the recipient mice because of low or no antigenicity.

1,121 citations


Journal Article
TL;DR: Findings support that pharmacological inhibition of the enzymatic activity of the vascular endothelial growth factor receptor represents a novel strategy for limiting the growth of a wide variety of tumor types.
Abstract: SU5416, a novel synthetic compound, is a potent and selective inhibitor of the Flk-1/KDR receptor tyrosine kinase that is presently under evaluation in Phase I clinical studies for the treatment of human cancers. SU5416 was shown to inhibit vascular endothelial growth factor-dependent mitogenesis of human endothelial cells without inhibiting the growth of a variety of tumor cells in vitro. In contrast, systemic administration of SU5416 at nontoxic doses in mice resulted in inhibition of subcutaneous tumor growth of cells derived from various tissue origins. The antitumor effect of SU5416 was accompanied by the appearance of pale white tumors that were resected from drug-treated animals, supporting the antiangiogenic property of this agent. These findings support that pharmacological inhibition of the enzymatic activity of the vascular endothelial growth factor receptor represents a novel strategy for limiting the growth of a wide variety of tumor types.

1,081 citations


Journal Article
TL;DR: The data indicate that DD3 is one of the most prostate cancer-specific genes yet described, and this makes DD3 a promising marker for the early diagnosis of prostate cancer and provides a powerful tool for the development of new treatment strategies for prostate cancer patients.
Abstract: Prostate cancer is the most commonly diagnosed malignancy and the second leading cause of cancer-related deaths in the Western male population. Despite the tremendous efforts that have been made to improve the early detection of this disease and to design new treatment modalities, there is still an urgent need for new markers and therapeutic targets for the management of prostate cancer patients. Using differential display analysis to compare the mRNA expression patterns of normal versus tumor tissue of the human prostate, we identified a cDNA, DD3, which is highly overexpressed in 53 of 56 prostatic tumors in comparison to nonneoplastic prostatic tissue of the same patients. Reverse transcription-PCR analysis using DD3-specific primers indicated that the expression of DD3 is very prostate specific because no product could be amplified in 18 different normal human tissues studied. Also, in a sampling of other tumor types and a large number of cell lines, no expression of DD3 could be detected. Molecular characterization of the DD3 transcription unit revealed that alternative splicing and alternative polyadenylation occur. The fact that no extensive open reading frame could be found suggests that DD3 may function as a noncoding RNA. The DD3 gene was mapped to chromosome 9q21-22, and no homology of DD3 to any gene present in the computer databases was found. Our data indicate that DD3 is one of the most prostate cancer-specific genes yet described, and this makes DD3 a promising marker for the early diagnosis of prostate cancer and provides a powerful tool for the development of new treatment strategies for prostate cancer patients.

1,070 citations


Journal Article
TL;DR: Investigation of aberrant promoter hypermethylation of cancer-related genes in serum may be useful for cancer diagnosis or the detection of recurrence in patients with non-small cell lung cancer.
Abstract: Recent evidence suggests that tumor cells may release DNA into the circulation, which is enriched in the serum and plasma, allowing detection of ras and p53 mutations and microsatellite alterations in the serum DNA of cancer patients. We examined whether aberrant DNA methylation might also be found in the serum of patients with non-small cell lung cancer. We tested 22 patients with non-small cell lung cancer using methylation-specific PCR, searching for promoter hypermethylation of the tumor suppressor gene p16, the putative metastasis suppressor gene death-associated protein kinase, the detoxification gene glutathione S-transferase P1, and the DNA repair gene O6-methylguanine-DNA-methyltransferase. Aberrant methylation of at least one of these genes was detected in 15 of 22 (68%) NSCLC tumors but not in any paired normal lung tissue. In these primary tumors with methylation, 11 of 15 (73%) samples also had abnormal methylated DNA in the matched serum samples. Moreover, none of the sera from patients with tumors not demonstrating methylation was positive. Abnormal promoter methylation in serum DNA was found in all tumor stages. Although these results need to be confirmed in larger studies and in other tumor types, detection of aberrant promoter hypermethylation of cancer-related genes in serum may be useful for cancer diagnosis or the detection of recurrence.

954 citations


Journal Article
TL;DR: It is reported that VEGF expression is induced in Lewis lung carcinomas (LLCs) both in vitro and in vivo after exposure to ionizing radiation (IR) and in human tumor cell lines (Seg-1 esophageal adenocarcinoma, SQ20B squamous cell carcinoma, T98 and U87 glioblastomas, and U1 melanoma) in vitro.
Abstract: The family of vascular endothelial growth factor (VEGF) proteins include potent and specific mitogens for vascular endothelial cells that function in the lation of angiogenesis Inhibition of VEGF-induced angiogenesis either by neutralizing antibodies or dominant-negative soluble receptor, blocks the growth of primary and metastatic experimental tumors Here we report that VEGF expression is induced in Lewis lung carcinomas (LLCs) both in vitro and vivo after exposure to ionizing radiation (IR) and in human tumor cell lines (Seg-1 esophageal adenocarcinoma, SQ20B squamous cell carcinoma, T98 and U87 glioblastomas, and U1 melanoma) in vitro. The biological significance of IR-induced VEGF production is supported by our finding that treatment of tumor-bearing mice (LLC, Seg-1, SQ20B, and U87) with a neutralizing antibody to VEGF-165 before irradiation is associated with a greater than additive antitumor effect. In vitro, the addition of VEGF decreases IR-induced killing of human umbilical vein endothelial cells, and the anti-VEGF treatment potentiates IR-induced lethality of human umbilical vein endothelial cells. Neither recombinant VEGF protein nor neutralizing antibody to VEGF affects the radiosensitivity of tumor cells These findings support a model in which induction of VEGF by IR contributes to the protection of tumor blood vessels from radiation-mediated cytotoxicity and thereby to tumor radioresistance.

842 citations


Journal Article
TL;DR: Prostate-specific membrane antigen (PSMA) was consistently expressed in the neovasculature of a wide variety of malignant neoplasms and may be an effective target for mAb-based antinesculature therapy.
Abstract: Prostate-specific membrane antigen (PSMA) is a type II integral membrane glycoprotein that was initially characterized by the monoclonal antibody (mAb) 7E11. PSMA is highly expressed in prostate secretory-acinar epithelium and prostate cancer as well as in several extraprostatic tissues. Recent evidence suggests that PSMA is also expressed in tumor-associated neovasculature. We examined the immunohistochemical characteristics of 7E11 and those of four recently developed anti-PSMA mAbs (J591, J415, and Hybritech PEQ226.5 and PM2J004.5), each of which binds a distinct epitope of PSMA. Using the streptavidin-biotin method, we evaluated these mAbs in viable prostate cancer cell lines and various fresh-frozen benign and malignant tissue specimens. In the latter, we compared the localization of the anti-PSMA mAbs to that of the anti-endothelial cell mAb CD34. With rare exceptions, all five anti-PSMA mAbs reacted strongly with the neovasculature of a wide spectrum of malignant neoplasms: conventional (clear cell) renal carcinoma (11 of 11 cases), transitional cell carcinoma of the urinary bladder (6 of 6 cases), testicular embryonal carcinoma (1 of 1 case), colonic adenocarcinoma (5 of 5 cases), neuroendocrine carcinoma (5 of 5 cases), glioblastoma multiforme (1 of 1 cases), malignant melanoma (5 of 5 cases), pancreatic duct carcinoma (4 of 4 cases), non-small cell lung carcinoma (5 of 5 cases), soft tissue sarcoma (5 of 6 cases), breast carcinoma (5 of 6 cases), and prostatic adenocarcinoma (2 of 12 cases). Localization of the anti-PSMA mAbs to tumor-associated neovasculature was confirmed by CD34 immunohistochemistry in sequential tissue sections. Normal vascular endothelium in non-cancer-bearing tissue was consistently PSMA negative. The anti-PSMA mAbs reacted with the neoplastic cells of prostatic adenocarcinoma (12 of 12 cases) but not with the neoplastic cells of any other tumor type, including those of benign and malignant vascular tumors (0 of 3 hemangiomas, 0 of 1 hemangioendothelioma, and 0 of 1 angiosarcoma). The mAbs to the extracellular PSMA domain (J591, J415, and Hybritech PEQ226.5) bound viable prostate cancer cells (LNCaP and PC3-PIP), whereas the mAbs to the intracellular domain (7E11 and Hybritech PM2J004.5) did not. All five anti-PSMA mAbs reacted with fresh-frozen benign prostate secretory-acinar epithelium (28 of 28 cases), duodenal columnar (brush border) epithelium (11 of 11 cases), proximal renal tubular epithelium (5 of 5 cases), colonic ganglion cells (1 of 12 cases), and benign breast epithelium (8 of 8 cases). A subset of skeletal muscle cells was positive with 7E11 (7 of 7 cases) and negative with the other four anti-PSMA mAbs. PSMA was consistently expressed in the neovasculature of a wide variety of malignant neoplasms and may be an effective target for mAb-based antineovasculature therapy.

811 citations


Journal Article
TL;DR: High levels of expression in the S1-M1-80 cells and in the human breast cancer subline, MCF-7 AdVp3000, are consistent with the identification of a new ATP binding cassette transporter, which is overexpressed in mitoxantrone-resistant cells.
Abstract: Reports of multiple distinct mitoxantrone-resistant sublines without overexpression of P-glycoprotein or the multidrug-resistance associated protein have raised the possibility of the existence of another major transporter conferring drug resistance. In the present study, a cDNA library from mitoxantrone-resistant S1-M1-80 human colon carcinoma cells was screened by differential hybridization. Two cDNAs of different lengths were isolated and designated MXR1 and MXR2. Sequencing revealed a high degree of homology for the cDNAs with Expressed Sequence Tag sequences previously identified as belonging to an ATP binding cassette transporter. Homology to the Drosophila white gene and its homologues was found for the predicted amino acid sequence. Using either cDNA as a probe in a Northern analysis demonstrated high levels of expression in the S1-M1-80 cells and in the human breast cancer subline, MCF-7 AdVp3000. Levels were lower in earlier steps of selection, and in partial revertants. The gene is amplified 10-12-fold in the MCF-7 AdVp3000 cells, but not in the S1-M1-80 cells These studies are consistent with the identification of a new ATP binding cassette transporter, which is overexpressed in mitoxantrone-resistant cells.

Journal Article
TL;DR: It is suggested that INI1 is a tumor suppressor gene involved in rhabdoid tumors of the brain, kidney, and other extrarenal sites.
Abstract: We examined 18 atypical teratoid and rhabdoid tumors of the brain and 7 renal and 4 extrarenal rhabdoid tumors for mutations in the candidate rhabdoid tumor suppressor gene, INI1. Fifteen tumors had homozygous deletions of one or more exons of the INI1 gene, and the other 14 tumors demonstrated mutations. Germ-line mutations of INI1 were identified in four children, one with an atypical teratoid tumor of the brain and three with renal rhabdoid tumors. These studies suggest that INI1 is a tumor suppressor gene involved in rhabdoid tumors of the brain, kidney, and other extrarenal sites.

Journal Article
TL;DR: It is demonstrated for the first time that platelets directly protect tumor cells from NK lysis in vitro as well as in vivo, thereby promoting metastasis and surface shielding by platelet aggregates seems to be the main mechanism.
Abstract: Natural killer (NK) cells provide effective antitumoral activity in the blood stream of mice, leading to reduced metastasis. There are, however, tumor cells that metastasize despite the presence of an intact NK system. The capability of tumor cells to induce platelet aggregation, on the other hand, correlates with their enhanced metastatic potential. A counteractive role of platelets for the NK function in metastasis has never been conceived. Here we demonstrate for the first time that platelets directly protect tumor cells from NK lysis in vitro as well as in vivo. Using three different tumor cell lines in a mouse model of experimental metastasis, tumor seeding in the target organs was reduced when the host was platelet depleted, but only if the tumor cells were NK sensitive. Aggregation of platelets around tumor cells also inhibited in vitro NK tumorilytic activity. This protection of tumor cells by platelets was mouse strain independent and was equally observed with platelets from β2-microglobulin-deficient mice, excluding a NK inhibitory function of MHC class I on platelets. Thus, even if tumor cells are NK susceptible and cytotoxic NK cells threaten their survival in the blood, platelets are capable of protecting them from cytolysis, thereby promoting metastasis. Surface shielding by platelet aggregates seems to be the main mechanism of this protection.

Journal Article
TL;DR: Because wild-type p53 predisposes cells to a more rapid rate of cell death after DNA damage, that short-term assays have led to the conclusion that mutations in p53 confer resistance to genotoxic agents, this tenet may need to be reexamined for human tumors of nonhematological origin.
Abstract: A widely held tenet of present day oncology is that tumor cells treated with anticancer agents die from apoptosis, and that cells resistant to apoptosis are resistant to cancer treatment. We suggest, in this review, that this tenet may need to be reexamined for human tumors of nonhematological origin, for two principal reasons: (a) cell killing has often been assessed in short term assays that are more influenced by the rate, than the overall level, of cell killing. This has tended to underestimate cell killing for cells not susceptible to apoptosis or having mutant p53; and (b) conclusions from experiments with normal cells transformed with dominant oncogenes have often been extrapolated to tumor cells. This does not take into account the fact that tumor cells have invariably undergone selection to an apoptotically resistant phenotype. In this review, we examine the impact of these two factors with particular emphasis on the influence of mutations in p53 on the sensitivity of tumor cells to DNA-damaging agents. We find that because wild-type p53 predisposes cells to a more rapid rate of cell death after DNA damage, particularly with normal or minimally transformed cells, that short-term assays have led to the conclusion that mutations in p53 confer resistance to genotoxic agents. On the other hand, if clonogenic survival is used to assess killing in cells derived from actual solid human tumors, then apoptosis and the genes controlling it, such as p53 and bcl-2, appear to play little or no role in the sensitivity of these cells to killing by anticancer drugs and radiation.

Journal Article
TL;DR: The conclusion that anti-Flk-1 mAb treatment inhibits tumor growth by suppression of tumor-induced neovascularization is supported and the potential for therapeutic application of anti-VEGF receptor antibody in the treatment of angiogenesis-dependent tumors is demonstrated.
Abstract: Tumor angiogenesis is mediated by tumor-secreted angiogenic growth factors that interact with their surface receptors expressed on endothelial cells. Vascular endothelial growth factor (VEGF) and its receptor [fetal liver kinase 1 (Flk-1)/kinase insert domain-containing receptor] play an important role in vascular permeability and tumor angiogenesis. Previously, we reported on the development of anti-Flk-1 and antikinase insert domain-containing receptor monoclonal antibodies (mAbs) that potently inhibit VEGF binding and receptor signaling. Here, we report the effect of anti-Flk-1 mAb (DC101) on angiogenesis and tumor growth. Angiogenesis in vivo was examined using a growth factor supplemented (basic fibroblast growth factor + VEGF) Matrigel plug and an alginate-encapsulated tumor cell (Lewis lung) assay in C57BL/6 mice. Systemic administration of DC101 every 3 days markedly reduced neovascularization of Matrigel plugs and tumor-containing alginate beads in a dose-dependent fashion. Histological analysis of Matrigel plugs showed reduced numbers of endothelial cells and vessel structures. Several mouse tumors and human tumor xenografts in athymic mice were used to examine the effect of anti-Flk-1 mAb treatment on tumor angiogenesis and growth. Anti-Flk-1 mAb treatment significantly suppressed the growth of primary murine Lewis lung, 4T1 mammary, and B16 melanoma tumors and growth of Lewis lung metastases. DC101 also completely inhibited the growth of established epidermoid, glioblastoma, pancreatic, and renal human tumor xenografts. Histological examination of anti-Flk-1 mAb-treated tumors showed evidence of decreased microvessel density, tumor cell apoptosis, decreased tumor cell proliferation, and extensive tumor necrosis. These findings support the conclusion that anti-Flk-1 mAb treatment inhibits tumor growth by suppression of tumor-induced neovascularization and demonstrate the potential for therapeutic application of anti-VEGF receptor antibody in the treatment of angiogenesis-dependent tumors.

Journal Article
TL;DR: The BCL-2 gene was identified at the chromosomal breakpoint of t(14; 18)-bearing human follicular B cell lymphomas and proved to block programmed cell death rather than promote proliferation, initiating a new category of oncogenes, regulators of cell death.
Abstract: The BCL-2 gene was identified at the chromosomal breakpoint of t(14; 18)-bearing human follicular B cell lymphomas. BCL-2 proved to block programmed cell death rather than promote proliferation. Transgenic mice that overexpress Bcl-2 in the B cell lineage demonstrate extended cell survival and progress to high-grade lymphomas. Thus, BCL-2 initiated a new category of oncogenes, regulators of cell death. Bcl-2-deficient mice demonstrate fulminant apoptosis of lymphocytes, profound renal cell death and loss of melanocytes. BCL-2 protein duels with its counteracting twin, a partner known as BAX. When BAX is in excess, cells execute a death command; but, when BCL-2 dominates, the program is inhibited and cells survive. Bax-deficient mice display cellular hyperplasia, confirming its role as a proapoptotic molecule. An expanded family of BCL-2-related proteins shares homology clustered within four conserved regions termed BCL-2 homology 1 through 4 (BH1-4). These novel domains control the ability of these proteins to dimerize and function. An amphipathic alpha helix, BH3, is of particular importance for the proapoptotic family members. BID and BAD represent an evolving set of proapoptotic molecules, which bear sequence homology only at BH3. They appear to reside more proximal in the pathway serving as death ligands. BAD connects upstream signal transduction paths with the BCL-2 family, modulating this checkpoint for apoptosis. In the presence of survival factor interleukin-3, cells phosphorylate BAD on two serine residues. This inactivated BAD is held by the 14-3-3 protein, freeing BCL-XL and BCL-2 to promote survival. Activation of BAX results in the initiation of apoptosis. Downstream events in this program include mitochondrial dysfunction, as well as Caspase activation. The pro- and antiapoptotic BCL-2 family members represent central regulators in an evolutionarily conserved pathway of cell death. Aberrations in the BCL-2 family result in disordered homeostasis, a pathogenic event in diseases, including cancer.

Journal Article
TL;DR: Results suggest that quantitative analysis of plasma EBV DNA may be a useful clinical and research tool in the screening and monitoring of NPC patients.
Abstract: Using real-time quantitative PCR, cell-free EBV DNA was detectable in the plasma of 96% (55 of 57) of nasopharyngeal carcinoma (NPC) patients (median concentration, 21058 copies/ml) and 7% (3 of 43) of controls (median concentration, 0 copies/ml) Advanced-stage NPC patients had higher plasma EBV DNA levels than those with early-stage disease At 1 month after completion of radiotherapy, plasma EBV DNA was undetectable in 7 of 15 subjects (47%) but remained high in the remaining 8 subjects (53%) Clinical examination revealed that all of the former seven subjects had complete tumor regression, whereas six of the eight latter subjects exhibited evidence of disease persistence or had developed distant metastases These results suggest that quantitative analysis of plasma EBV DNA may be a useful clinical and research tool in the screening and monitoring of NPC patients

Journal Article
TL;DR: Examination of C225 effects on radiation response in SCCs demonstrates enhancement in radiosensitivity and amplification of radiation-induced apoptosis, and C225 represents a promising growth-inhibitory agent that can influence cellular proliferation, apoptosis and radiosensitivity in S CCs of the head and neck.
Abstract: We examined effects of the anti-epidermal growth factor receptor monoclonal antibody C225 on proliferation, cell cycle phase distribution, apoptosis, and radiosensitivity in squamous cell carcinoma (SCC) cell lines derived from head and neck cancer patients Exposure to C225 in culture inhibits SCC proliferation in a time-dependent manner, and the degree of growth inhibition, compared to controls, ranges from 20 to 75% Flow cytometry analysis demonstrates that C225 treatment induces accumulation of cells in G1, which is accompanied by a 2-3-fold decrease in the percentage of cells in S phase C225 exposure also induces apoptosis in SCC populations, as demonstrated by flow cytometry analysis using dual stainings of merocyanine 540 and Hoechst 33342 Western blot analysis indicates that C225 exposure induces accumulation of hypophosphorylated retinoblastoma protein and increases expression of p27KIP1 An increase in Bax expression and concurrent decrease in Bcl-2 expression are observed when SCC cells are exposed to C225 Examination of C225 effects on radiation response in SCCs demonstrates enhancement in radiosensitivity and amplification of radiation-induced apoptosis These effects are observed in both single-dose and fractionated radiation experiments C225 represents a promising growth-inhibitory agent that can influence cellular proliferation, apoptosis, and radiosensitivity in SCCs of the head and neck

Journal Article
TL;DR: Results suggest that COX-2 may be a target for the prevention or treatment of HNSCC.
Abstract: The purpose of this study was to determine whether cyclooxygenase-2 (COX-2) was overexpressed in squamous cell carcinoma of the head and neck (HNSCC). Quantitative reverse transcription-PCR, immunoblotting, and immunohistochemistry were used to assess the expression of COX-2 in head and neck tissue. Mean levels of COX-2 mRNA were increased by nearly 150-fold in HNSCC (n = 24) compared with normal oral mucosa from healthy volunteers (n = 17). Additionally, there was about a 50-fold increase in amounts of COX-2 mRNA in normal-appearing epithelium adjacent to HNSCC (n = 10) compared with normal oral mucosa from healthy volunteers. Immunoblotting demonstrated that COX-2 protein was present in six of six cases of HNSCC but was undetectable in normal oral mucosa from healthy subjects. Immunohistochemical analysis showed that COX-2 was expressed in both HNSCC and adjacent normal-appearing epithelium. Taken together, these results suggest that COX-2 may be a target for the prevention or treatment of HNSCC.

Journal Article
TL;DR: Results of this study suggest that COX-2 may be a target for the prevention or treatment of pancreatic cancer.
Abstract: A large body of evidence suggests that cyclooxygenase-2 (COX-2) is important in gastrointestinal cancer. The purpose of this study was to determine whether COX-2 was expressed in adenocarcinoma of the human pancreas. Quantitative reverse transcription-PCR, immunoblotting, and immunohistochemistry were used to assess the expression of COX-2 in pancreatic tissue. Levels of COX-2 mRNA were increased by >60-fold in pancreatic cancer compared to adjacent nontumorous tissue. COX-2 protein was present in 9 of 10 cases of adenocarcinoma of the pancreas but was undetectable in nontumorous pancreatic tissue. Immunohistochemical analysis showed that COX-2 was expressed in malignant epithelial cells. In cultured human pancreatic cancer cells, levels of COX-2 mRNA and protein were induced by treatment with tumor-promoting phorbol esters. Taken together, these results suggest that COX-2 may be a target for the prevention or treatment of pancreatic cancer.

Journal Article
TL;DR: It is demonstrated that insulin, insulin-like growth factor (IGF)-1, and IGF-2 induce expression of HIF-1alpha, which is required for expression of genes encoding IGF- 2, IGF-binding protein (IGfBP)-2 and IGFBP-3.
Abstract: Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding glucose transporters, glycolytic enzymes, vascular endothelial growth factor, and other proteins involved in O 2 homeostasis and tumor progression. The expression and transcriptional activity of the HIF-1α subunit is regulated by the cellular O 2 concentration. We demonstrate that insulin, insulin-like growth factor (IGF)-1, and IGF-2 induce expression of HIF-1α, which is required for expression of genes encoding IGF-2, IGF-binding protein (IGFBP)-2 and IGFBP-3. These data provide a novel mechanism by which HIF-1α overexpression may occur in tumor cells and contribute to an autocrine growth factor loop.

Journal Article
TL;DR: Examination of plasma concentrations of several major antioxidants and risk of prostate cancer found lycopene was the only antioxidant found at significantly lower mean levels in cases than in matched controls, and the inverse association was particularly apparent for aggressive cancer and for men not consuming beta-carotene supplements.
Abstract: Dietary consumption of the carotenoid lycopene (mostly from tomato products) has been associated with a lower risk of prostate cancer. Evidence relating other carotenoids, tocopherols, and retinol to prostate cancer risk has been equivocal. This prospective study was designed to examine the relationship between plasma concentrations of several major antioxidants and risk of prostate cancer. We conducted a nested case-control study using plasma samples obtained in 1982 from healthy men enrolled in the Physicians’ Health Study, a randomized, placebo-controlled trial of aspirin and β-carotene. Subjects included 578 men who developed prostate cancer within 13 years of follow-up and 1294 age- and smoking status-matched controls. We quantified the five major plasma carotenoid peaks (α- and β-carotene, β-cryptoxanthin, lutein, and lycopene) plus α- and γ-tocopherol and retinol using high-performance liquid chromatography. Results for plasma β-carotene are reported separately. Odds ratios (ORs), 95% confidence intervals (CIs), and P s for trend were calculated for each quintile of plasma antioxidant using logistic regression models that allowed for adjustment of potential confounders and estimation of effect modification by assignment to either active β-carotene or placebo in the trial. Lycopene was the only antioxidant found at significantly lower mean levels in cases than in matched controls ( P = 0.04 for all cases). The ORs for all prostate cancers declined slightly with increasing quintile of plasma lycopene (5th quintile OR = 0.75, 95% CI = 0.54–1.06; P , trend = 0.12); there was a stronger inverse association for aggressive prostate cancers (5th quintile OR = 0.56, 95% CI = 0.34–0.91; P , trend = 0.05). In the placebo group, plasma lycopene was very strongly related to lower prostate cancer risk (5th quintile OR = 0.40; P , trend = 0.006 for aggressive cancer), whereas there was no evidence for a trend among those assigned to β-carotene supplements. However, in the β-carotene group, prostate cancer risk was reduced in each lycopene quintile relative to men with low lycopene and placebo. The only other notable association was a reduced risk of aggressive cancer with higher α-tocopherol levels that was not statistically significant. None of the associations for lycopene were confounded by age, smoking, body mass index, exercise, alcohol, multivitamin use, or plasma total cholesterol level. These results concur with a recent prospective dietary analysis, which identified lycopene as the carotenoid with the clearest inverse relation to the development of prostate cancer. The inverse association was particularly apparent for aggressive cancer and for men not consuming β-carotene supplements. For men with low lycopene, β-carotene supplements were associated with risk reductions comparable to those observed with high lycopene. These data provide further evidence that increased consumption of tomato products and other lycopene-containing foods might reduce the occurrence or progression of prostate cancer.

Journal Article
TL;DR: It is reported here that ALT cells contain a novel promyelocytic leukemia (PML) body (ALT-associated PML body, APB), which are large donut-shaped nuclear structures containing PML protein, telomeric DNA, and the telomere binding proteins human telomerre repeat binding factors 1 and 2.
Abstract: Telomerase-negative immortalized human cells maintain their telomeres by a mechanism known as alternative lengthening of telomeres (ALT). We report here that ALT cells contain a novel promyelocytic leukemia (PML) body (ALT-associated PML body, APB). APBs are large donut-shaped nuclear structures containing PML protein, telomeric DNA, and the telomere binding proteins human telomere repeat binding factors 1 and 2. Immunostaining showed that APBs also contain replication factor A, RAD51, and RAD52, proteins involved in DNA synthesis and recombination. During immortalization, APBs appeared at exactly the same time as activation of ALT. APBs were found in ALT tumors and cell lines but not in mortal cell strains or in telomerase-positive cell lines or tumors.

Journal Article
TL;DR: It is demonstrated that COX-2 is expressed in the majority of esophageal SCCs and ADCs and that COx-2-derived PGs play an important role in the regulation of proliferation and apoptosis of esphageal tumor cells.
Abstract: On the basis of epidemiological observations that nonsteroidal anti-inflammatory drugs reduce the risk of esophageal carcinoma, we studied the expression of cyclooxygenase-2 (COX-2) in esophageal squamous cell carcinomas (SCCs; n = 172) and in esophageal adenocarcinomas (ADCs; n = 27). Using immunohistochemistry, we observed COX-2 expression in 91% of the SCCs and in 78% of the ADCs. Western blot analysis showed enhanced expression of the COX-2 protein in some tumors as compared with normal esophageal squamous epithelium, whereas similar amounts of the COX-1 protein were found in normal and cancerous tissues. COX expression was also studied in two esophageal cancer cell lines (OSC-1 and OSC-2) to evaluate the functional relevance of COX-2-derived prostaglandins (PGs). OSC-2 cells expressed COX-2 but not COX-1, whereas OSC-1 cells expressed high levels of COX-1 but showed only a very weak COX-2 expression. Accordingly, PGE2 synthesis was 600 times higher in the OSC-2 cells as compared with the OSC-1 cells. Treatment of OSC-2 cells with the selective COX-2 inhibitors flosulide and NS-398 concentration dependently suppressed PGE2 synthesis and proliferation and also induced apoptosis. In contrast, no effect of the COX-2 inhibitors was seen in OSC-1 cells. Our data demonstrate that COX-2 is expressed in the majority of esophageal SCCs and ADCs and that COX-2-derived PGs play an important role in the regulation of proliferation and apoptosis of esophageal tumor cells. It is concluded that inhibition of COX-2 may be useful in the therapy of esophageal cancer.

Journal Article
TL;DR: This work poses a quantitative theory for tumor growth under angiogenic stimulator/inhibitor control that is both explanatory and clinically implementable and reveals the existence of an ultimate limitation to tumor size underAngiogenic control.
Abstract: The effects of the angiogenic inhibitors endostatin, angiostatin, and TNP-470 on tumor growth dynamics are experimentally and theoretically investigated. On the basis of the data, we pose a quantitative theory for tumor growth under angiogenic stimulator/inhibitor control that is both explanatory and clinically implementable. Our analysis offers a ranking of the relative effectiveness of these inhibitors. Additionally, it reveals the existence of an ultimate limitation to tumor size under angiogenic control, where opposing angiogenic stimuli come into dynamic balance, which can be modulated by antiangiogenic therapy. The competitive influences of angiogenically driven growth and inhibition underlying this framework may have ramifications for tissue size regulation in general.

Journal Article
TL;DR: The recent development of new drugs that are nontoxic until they are activated in the hypoxic cell opens a new era of selective cancer therapy.
Abstract: It has been appreciated for more than 50 years that very low levels of oxygenation, or hypoxia, both protect cells from killing by X-irradiation and are present in solid tumors but not in normal tissues. Until recently, however, there has been no definitive proof that hypoxia in human tumors contributes to radiotherapy treatment failure. We now know that hypoxia in solid tumors is not only a major problem for radiation therapy but also leads to resistance to most anticancer drugs and, importantly, appears to accelerate malignant progression and increase metastasis. To date, efforts to overcome the problem of hypoxia have had only limited success. However, the recent development of new drugs that are nontoxic until they are activated in the hypoxic cell opens a new era. The first of these new drugs to be tested clinically, tirapazamine, a drug that is highly toxic to hypoxic but not aerobic cells, has already demonstrated efficacy in selective potentiation of cisplatin in randomized Phase III trials with non-small cell lung cancer. The unique presence of hypoxic cells in human tumors provides an important target for selective cancer therapy.

Journal Article
TL;DR: Loss of PTEN protein is correlated with pathological markers of poor prognosis in prostate cancer and correlated more significantly with a Gleason score of 7 or higher and with advanced pathological stage.
Abstract: The tumor suppressor gene PTEN/MMAC-1/TEP-1 (referred to hereafter as PTEN) maps to chromosome 10q23 and encodes a dual specificity phosphatase. The PTEN protein negatively regulates cell migration and cell survival and induces a G1 cell cycle block via negative regulation of the phosphatidylinositol 3'-kinase/protein kinase B/Akt signaling pathway. PTEN is frequently mutated or deleted in both prostate cancer cell lines and primary prostate cancers. A murine polyclonal antiserum was raised against a glutathione S-transferase fusion polypeptide of the COOH terninus of PTEN. Archival paraffin tissue sections from 109 cases of resected prostate cancer were immunostained with the antiserum, using DU145 and PC-3 cells as positive and negative controls, respectively. PTEN expression was seen in the secretory cells. Cases were considered positive when granular cytoplasmic staining was seen in all tumor cells, mixed when areas of both positive and negative tumor cell clones were seen, and negative when adjacent benign prostate tissue but not tumor tissue showed positive staining. Seventeen cases (15.6%) of prostate cancer were positive, 70 cases (64.2%) were mixed, and 22 cases (20.2%) were negative. Total absence of PTEN expression correlated with the Gleason score (P = 0.0081) and correlated more significantly with a Gleason score of 7 or higher (P = 0.0004) and with advanced pathological stage (American Joint Committee on Cancer stages T3b and T4; P = 0.0078). Thus, loss of PTEN protein is correlated with pathological markers of poor prognosis in prostate cancer.

Journal Article
TL;DR: FISH to tissue microarray sections enables high-throughput analysis of genetic alterations contributing to cancer development and progression and implicate a role for amplification of androgen receptor in hormonal therapy failure and that of MYC in the metastatic progression of human prostate cancer.
Abstract: Prostate cancer development and progression is driven by the accumulation of genetic changes, the nature of which remains incompletely understood. To facilitate high-throughput analysis of molecular events taking place in primary, recurrent, and metastatic prostate cancer, we constructed a tissue microarray containing small 0.6-mm cylindrical samples acquired from 371 formalin-fixed blocks, including benign prostatic hyperplasia ( n = 32) and primary tumors ( n = 223), as well as both locally recurrent tumors ( n = 54) and metastases ( n = 62) from patients with hormone-refractory disease. Fluorescence in situ hybridization (FISH) was applied to the analysis of consecutive tissue microarray sections with probes for five different genes. High-level (≥3X) amplifications were very rare (

Journal Article
TL;DR: Administration of curcumin to the rats during the initiation and postinitiation stages and throughout the promotion/progression stage increased apoptosis in the colon tumors as compared to colon tumors in the groups receiving AOM and the control diet.
Abstract: Curcumin, derived from the rhizome of Curcuma longa L. and having both antioxidant and anti-inflammatory properties, inhibits chemically induced carcinogenesis in the skin, forestomach, and colon when it is administered during initiation and/or postinitiation stages. This study was designed to investigate the chemopreventive action of curcumin when it is administered (late in the premalignant stage) during the promotion/progression stage of colon carcinogenesis in male F344 rats. We also studied the modulating effect of this agent on apoptosis in the tumors. At 5 weeks of age, groups of male F344 rats were fed a control diet containing no curcumin and an experimental AIN-76A diet with 0.2% synthetically derived curcumin (purity, 99.9%). At 7 and 8 weeks of age, rats intended for carcinogen treatment were given s.c. injections of azoxymethane (AOM) at a dose rate of 15 mg/kg body weight per week. Animals destined for the promotion/progression study received the AIN-76A control diet for 14 weeks after the second AOM treatment and were then switched to diets containing 0.2 and 0.6% curcumin. Premalignant lesions in the colon would have developed by week 14 following AOM treatment. They continued to receive their respective diets until 52 weeks after carcinogen treatment and were then sacrificed. The results confirmed our earlier study in that administration of 0.2% curcumin during both the initiation and postinitiation periods significantly inhibited colon tumorigenesis. In addition, administration of 0.2% and of 0.6% of the synthetic curcumin in the diet during the promotion/progression stage significantly suppressed the incidence and multiplicity of noninvasive adenocarcinomas and also strongly inhibited the multiplicity of invasive adenocarcinomas of the colon. The inhibition of adenocarcinomas of the colon was, in fact, dose dependent. Administration of curcumin to the rats during the initiation and postinitiation stages and throughout the promotion/progression stage increased apoptosis in the colon tumors as compared to colon tumors in the groups receiving AOM and the control diet. Thus, chemopreventive activity of curcumin is observed when it is administered prior to, during, and after carcinogen treatment as well as when it is given only during the promotion/progression phase (starting late in premalignant stage) of colon carcinogenesis.

Journal Article
TL;DR: Findings demonstrate that AR mutations occur in response to strong selective pressure from flutamide treatment, and these mutations responded to subsequent treatment with bicalutamide, an AR antagonist that blocks the mutant ARs.
Abstract: The role of androgen receptor (AR) mutations in androgen-independent prostate cancer (PCa) was determined by examining AR transcripts and genes from a large series of bone marrow metastases. Mutations were found in 5 of 16 patients who received combined androgen blockade with the AR antagonist flutamide, and these mutant ARs were strongly stimulated by flutamide. In contrast, the single mutant AR found among 17 patients treated with androgen ablation monotherapy was not flutamide stimulated. Patients with flutamide-stimulated AR mutations responded to subsequent treatment with bicalutamide, an AR antagonist that blocks the mutant ARs. These findings demonstrate that AR mutations occur in response to strong selective pressure from flutamide treatment.