Showing papers in "Cancer Science in 2009"

Cancer/testis (CT) antigens: potential targets for immunotherapy.

Abstract: Cancer/testis (CT) antigens are protein antigens with normal expression restricted to adult testicular germ cells, and yet are aberrantly activated and expressed in a proportion of various types of human cancer. At least a subset of this group of antigens has been found to elicit spontaneous humoral and cell-mediated immune responses in cancer patients, raising the possibility that these antigens could be cancer vaccine targets. More than 100 CT antigen genes have been reported in the literature, with approximately 30 being members of multigene families on the X chromosome, so-called CT-X genes. Most CT-X genes are expressed at the spermatogonia stage of spermatogenesis, and their functions are mostly unknown. In cancer, the frequency of CT antigen expression is highly variable among different tumor types, but is more often expressed in high-grade late-stage cases in general. Cancer vaccine trials based on CT antigens MAGE-A3 and NY-ESO-1 are currently ongoing, and these antigens may also play a role in antigen-specific adoptive T-cell transfer and in the immunomodulation approach of cancer therapy.

Preclinical and clinical studies of anticancer agent-incorporating polymer micelles

Abstract: The size of anticancer agent-incorporating micelles can be controlled within the diameter range of 20-100 nm to ensure that they do not penetrate normal vessel walls. With this development, it is expected that the incidence of drug-induced side-effects may be decreased owing to the reduced drug distribution in normal tissue. Micelle systems can also evade non-specific capture by the reticuloendothelial system because the outer shell of a micelle is covered with polyethylene glycol. Consequently, a polymer micelle carrier can be delivered selectively to a tumor by utilizing the enhanced permeability and retention effect. Moreover, a water-insoluble drug can be incorporated into polymer micelles. Presently, several anticancer agent-incorporating micelle carrier systems are under preclinical and clinical evaluation. Furthermore, nucleic acid-incorporating micelle carrier systems are also being developed.

Role of iron in carcinogenesis: cancer as a ferrotoxic disease.

Abstract: Iron is abundant universally. During the evolutionary processes, humans have selected iron as a carrier of oxygen inside the body. However, iron works as a double-edged sword, and its excess is a risk for cancer, presumably via generation of reactive oxygen species. Thus far, pathological conditions such as hemochromatosis, chronic viral hepatitis B and C, exposure to asbestos fibers, as well as endometriosis have been recognized as iron overload-associated risks for human cancer. Indeed, iron is carcinogenic in animal experiments. These reports unexpectedly revealed that there are target genes in iron-induced carcinogenesis and that iron-catalyzed oxidative DNA damage is not random in vivo. Several iron transporters and hepcidin, a peptide hormone regulating iron metabolism, were discovered in the past decade. Furthermore, a recent epidemiological study reported that iron reduction by phlebotomy decreased cancer risk in the apparently normal population. These results warrant reconsideration of the role of iron in carcinogenesis and suggest that fine control of body iron stores would be a wise strategy for cancer prevention.

Genetic alterations and signaling pathways in the evolution of gliomas

Abstract: Gliomas are the most common primary brain tumors. They account for more than 70% of all neoplasms of the central nervous system and vary considerably in morphology, location, genetic alterations, and response to therapy. Most frequent and malignant are glioblastomas. The vast majority (>90%) develops rapidly after a short clinical history and without evidence of a less malignant precursor lesion (primary or de novo glioblastoma). Secondary glioblastomas develop more slowly through progression from low-grade or anaplastic astrocytoma. These glioblastoma subtypes constitute distinct disease entities that affect patients of different age, develop through distinct genetic pathways, show different RNA and protein expression profiles, and may differ in their response to radio- and chemotherapy. Recently, isocitrate dehydrogenase 1 (IDH1) mutations have been identified as a very early and frequent genetic alteration in the pathway to secondary glioblastomas as well as that in oligodendroglial tumors, providing the first evidence that low-grade astrocytomas and oligodendrogliomas may share common cells of origin. In contrast, primary glioblastomas very rarely contain IDH1 mutations, suggesting that primary and secondary glioblastomas may originate from different progenitor cells, despite the fact that they are histologically largely indistinguishable. In this review, we summarize the current status of genetic alterations and signaling pathways operative in the evolution of astrocytic and oligodendroglial tumors.

Role of the miR-106b-25 microRNA cluster in hepatocellular carcinoma

Abstract: MicroRNAs are tiny RNA molecules which serve as important post-transcriptional regulators of gene expression. Dysregulated expression of microRNAs has been observed in human cancers, indicating that microRNAs may function as oncogenes or as tumor suppressors. To date, the microRNAs encoded by the oncogenic miR-17-92 cluster, and its paralog the miR-106b-25 cluster, are among those which are differentially expressed in human cancers. In this study, we examined and confirmed the over-expression of these clusters in hepatocellular carcinoma and in hepatoma-derived cells. At least 50% of the tumor samples showed a greater than two-fold increase in the expression for miR-18 and for the miR-106b-25 cluster when compared with the corresponding paired non-tumor samples. Knock-down studies for the miR-106b-25 cluster, which includes miR-106b, miR-93 and miR-25, showed that the expression of the cluster is necessary for cell proliferation and for anchorage-independent growth. In tumors with high expression of this cluster, reduced expression of the BH3-only protein Bim, a miR-25 target, was observed. We further identified the transcription factor E2F1 as a target gene for miR-106b and miR-93 and it is likely that one of the roles of the miR-106b-25 cluster is to prevent excessively high E2F1 expression, which may then cause apoptosis. We conclude that there is aberrant expression of microRNAs encoded by the oncogenic miR-17-92 cluster and the miR-106b-25 cluster in hepatocellular carcinoma. The consistent overexpression of the miR-106b-25 cluster and its role in cell proliferation and anchorage-independent growth points to the oncogenic potential of this cluster. (Cancer Sci 2009; 100: 1234–1242)

Activated hepatic stellate cells promote tumorigenicity of hepatocellular carcinoma

Abstract: Liver cirrhosis is the main risk factor for the development of hepatocellular carcinoma (HCC). Activated hepatic stellate cells (HSC) are the effector cells of hepatic fibrosis and also infiltrate the HCC stroma where they might play a critical role in HCC progression. Here we aimed to analyze the effects of activated HSC on the proliferation and growth of HCC cell lines in vitro and in vivo. Conditioned media (CM) collected from HSC significantly induced proliferation and migration of HCC cells cultured in monolayers. In a 3-dimensional spheroid coculture system, HSC promoted HCC growth and diminished the extent of central necrosis. In accordance, in vivo simultaneous implantation of HSC and HCC cells into nude mice promoted tumor growth and invasiveness, and inhibited necrosis formation. As potential mechanism of the tumorigenic effects of HSC we identified activation of NFkappaB and extracellular-regulated kinase (ERK) in HCC cells, two signaling cascades that play a crucial role in HCC progression. In summary, our data indicate that stromal HSC promotes HCC progression and suggest the HSC-HCC interaction as an interesting tumor differentiation-independent target for therapy of this highly aggressive cancer.

Stem cell marker aldehyde dehydrogenase 1-positive breast cancers are characterized by negative estrogen receptor, positive human epidermal growth factor receptor type 2, and high Ki67 expression.

Abstract: Recently, aldehyde dehydrogenase (ALDH) 1 has been identified as a reliable marker for breast cancer stem cells. The aim of our study was to investigate the clinicopathological characteristics of breast cancers with ALDH1+ cancer stem cells. In addition, the distribution of ALDH1+ tumor cells was compared on a cell-by-cell basis with that of estrogen receptor (ER)+, Ki67+, or human epidermal growth factor receptor type 2 (HER2)+ tumor cells by means of double immunohistochemical staining. Immunohistochemical staining of ALDH1 was applied to 203 primary breast cancers, and the results were compared with various clinicopathological characteristics of breast cancers including tumor size, histological grade, lymph node metastases, lymphovascular invasion, ER, progesterone receptor, HER2, Ki67, and topoisomerase 2A as well as prognosis. Immunohistochemical double staining of ALDH1 and ER, Ki67, or HER2 was also carried out to investigate their distribution. Of the 203 breast cancers, 21 (10%) were found to be ALDH1+, and these cancers were significantly more likely to be ER− (P = 0.004), progesterone receptor− (P = 0.025), HER2+ (P = 0.001), Ki67+ (P < 0.001), and topoisomerase 2A+ tumors (P = 0.012). Immunohistochemical double staining studies showed that ALDH1+ tumor cells were more likely to be ER−, Ki67−, and HER2+ tumor cells. Patients with ALDH1 (score 3+) tumors showed a tendency (P = 0.056) toward a worse prognosis than did those with ALDH1− tumors. Breast cancers with ALDH1+ cancer stem cells posses biologically aggressive phenotypes that tend to have a poor prognosis, and ALDH1+ cancer stem cells are characterized by ER−, Ki67−, and HER2+. (Cancer Sci 2009; 100: 1062–1068)

Glypican-3 expression is correlated with poor prognosis in hepatocellular carcinoma.

Abstract: The relationship between overexpression of glypican (GPC)-3 that is specific for hepatocellular carcinoma (HCC) and the prognosis has not yet been clarified. We attempted to determine the expression profile of GPC3 in association with the clinicopathological factors by immunohistochemical analysis in HCC patients and investigated the potential prognostic value of GPC3 by comparing the survival rate between the GPC3-positive and GPC3-negative HCC patients. Primary HCC tissue samples (n = 107) obtained from patients who had undergone hepatectomy between 2000 and 2001 were analyzed. GPC3 expression was less frequently observed in well-differentiated HCC than in moderately and poorly differentiated HCC, the difference in the frequency being statistically significant. GPC3-positive HCC patients had a significantly lower 5-year survival rate than the GPC3-negative HCC patients (54.5 vs 87.7%, P = 0.031). Among 80 of the 107 (74.6%) patients with initial treatment who underwent hepatectomy, none of GPC3-negative HCC patients (n = 16, 20.0%) died during the follow-up period. No deaths were noted in the GPC3-negative HCC patients among the 71 (88.7%) patients with moderately and poorly differentiated HCC. Multivariate analysis identified GPC3 expression (P = 0.034) as an independent prognostic factor for the overall survival. We showed that GPC3 expression is correlated with a poor prognosis in HCC patients.

Significance of nitroimidazole compounds and hypoxia-inducible factor-1 for imaging tumor hypoxia

Abstract: A tumor-specific microenvironment is characterized by hypoxia, in which oxygen tension is considerably lower than in normal tissues. The hypoxic status of various solid tumors has been attributed as an indicator of adverse prognosis due to tumor progression toward a more malignant phenotype with increased metastatic potential and resistance to treatment. Various exogenous and endogenous markers for hypoxia are currently available and studied in relation to each other, tumor architecture, and tumor microenvironment. Over the last few decades, various methods have been suggested to assess the level of oxygenation in solid tumors. Among them, nitroimidazole compounds have provided promising information on tumor hypoxia. To quantify the extent of hypoxia requires that nitroimidazole binding be primarily dependent on oxygen concentration as well as nitroreductase levels in the tumor cells. Furthermore, recent progress in molecular biology has highlighted a transcription factor, hypoxia-inducible factor (HIF)-1, whose activity is induced by hypoxia. HIF-1 plays a central role in malignant progression by inducing the expression of various genes, whose functions are strongly associated with malignant alteration of the entire tumor. The cellular changes induced by HIF-1 are extremely important therapeutic targets of cancer therapy, particularly in the therapy against refractory cancers. In this review, we will discuss the significance of pimonidazole and HIF-1 as exogenous and endogenous hypoxia markers, respectively, as well as their evaluation and imaging of tumor hypoxia.

Protein tyrosine phosphatase SHP-2: a proto-oncogene product that promotes Ras activation.

Abstract: SHP-2 is a cytoplasmic protein tyrosine phosphatase (PTP) that contains two Src homology 2 (SH2) domains. Although PTPs are generally considered to be negative regulators on the basis of their ability to oppose the effects of protein tyrosine kinases, SHP-2 is unusual in that it promotes the activation of the Ras-MAPK signaling pathway by receptors for various growth factors and cytokines. The molecular basis for the activation of SHP-2 is also unique: In the basal state, the NH(2)-terminal SH2 domain of SHP-2 interacts with the PTP domain, resulting in autoinhibition of PTP activity; the binding of SHP-2 via its SH2 domains to tyrosine-phosphorylated growth factor receptors or docking proteins, however, results in disruption of this intramolecular interaction, leading to exposure of the PTP domain and catalytic activation. Indeed, SHP-2 proteins with artificial mutations in the NH(2)-terminal SH2 domain have been shown to act as dominant active mutants in vitro. Such activating mutations of PTPN11 (human SHP-2 gene) were subsequently identified in individuals with Noonan syndrome, a human developmental disorder that is sometimes associated with juvenile myelomonocytic leukemia. Furthermore, somatic mutations of PTPN11 were found to be associated with pediatric leukemia. SHP-2 is also thought to participate in the development of other malignant disorders, but in a manner independent of such activating mutations. Biochemical and functional studies of SHP-2 and genetic analysis of PTPN11 in human disorders have thus converged to provide new insight into the pathogenesis of cancer as well as potential new targets for cancer treatment.

Application of 1H NMR-based metabonomics in the study of metabolic profiling of human hepatocellular carcinoma and liver cirrhosis.

Abstract: 1H nuclear magnetic resonance (NMR)-based metabonomics was used to characterize metabolic profiles of liver cirrhosis (LC) and hepatocellular carcinoma (HCC) We found compared to healthy humans, LC and HCC sera had higher levels of acetate, Nacetylglycoproteins, pyruvate, glutamine, alpha-ketoglutarate, glycerol, tyrosine, 1-methylhistidine and phenylalanine, together with lower levels of low-density lipoprotein, isoleucine, valine, acetoacetate, creatine, choline and unsaturated lipids Scores plot of pattern recognition analysis were capable of distinguishing LC and HCC patients from healthy humans These results indicate that serum NMR spectra combined with pattern recognition analysis techniques offer an efficient, convenient way of depicting tumor biochemistry, which may be of great benefit to early diagnosis of human malignant diseases using single blood samples

Roles of Nox1 and Other Nox Isoforms in Cancer Development

Abstract: The NADPH oxidase (Nox) family of enzymes generates reactive oxygen species (ROS). At low ROS concentration, intracellular signaling is initiated, whereas at high ROS concentration, oxidative stress is induced. The extensive studies over the years have shed light on the mediating roles of the Nox enzymes in a variety of normal physiological processes ranging from bactericidal activity to remodeling of the extracellular matrix. Consequently, imbalance of Nox activities could be the potential cause of acute or chronic diseases. With regard to functional relationships between Nox isoforms and pathogenesis, it is of particular interest to study whether they are involved in carcinogenesis, because overproduction of ROS has long been implicated as a risk factor in cancer development. We see one remarkable example of the causal relationship between Nox1 and cancer in Ras oncogene-induced cell transformation. Other studies also indicate that the Nox family of genes appears to be required for survival and growth of a subset of human cancer cells. Thus, the Nox family will be a focus of attention in cancer biology and etiology over the next couple years.

Leptin induces functional activation of cyclooxygenase-2 through JAK2/STAT3, MAPK/ERK, and PI3K/AKT pathways in human endometrial cancer cells

Abstract: Hyperleptinemia is a common feature of obese women who have a higher risk of endometrial cancer than women with normal weights, and epidemiologic studies have suggested a correlation between obesity and endometrial carcinoma. Therefore, understanding of the molecular mechanism involved in leptin signaling transduction is important in endometrial cancer prevention and treatment. In this study, both isoforms of the leptin receptor (Ob-R), the long form (Ob-Rb) and short form (Ob-Ra), were detected as being expressed in six endometrial cancer cell lines with various differentiation status by western blotting, and Ob-Ra was found to be more abundant than Ob-Rb in these cells. Moreover, the expressions of both isoforms were inversely correlated with histoprognostic grading. We also showed that leptin stimulated cell proliferation and induced activations of signal transducers and activators of transcription 3 (STAT3), extracellular signal-regulated kinase (ERK1/2), AKT, and cyclooxygenase (COX)-2 in endometrial cancer cells dose-dependently by [(3)H] thymidine incorporation assay and western blotting. Leptin-stimulation resulted in increased expression of COX-2 mRNA and prostaglandin E2 (PGE2) production of endometrial cancer cells by reverse transcription-polymerase chain reaction and enzyme immunoassay, respectively, which was effectively blocked by pharmacological inhibitors of Janus tyrosine kinase 2 (JAK2), AG490; of mitogen-activated protein kinase (MAPK) kinase, U0126; of phosphatidylinositol 3-kinase (PI3K), LY294002; and of COX-2, NS398. These results suggest that leptin promotes cell proliferation of endometrial cancer cells via the aforementioned multiple signal-transduction pathways. Leptin-induced functional activation of COX-2 is JAK2/STAT3-, MAPK/ERK-, and PI3K/AKT-dependent, indicating that COX-2 may be a critical factor of endometrial carcinogenesis in obesity.

Enhanced delivery of macromolecular antitumor drugs to tumors by nitroglycerin application

Abstract: Dose regimens of anticancer agents are usually designed on the basis of the maximum tolerable drug doses, and toxicity prevents drug usage at higher doses, even though the drugs may be more effective at the higher doses. We previously studied macromolecular anticancer drugs, i.e. those larger than 40 kDa, and observed their accelerated accumulation in tumors. Their concentration in tumors was more than 5-100-fold their blood concentration because of the enhanced permeability and retention (EPR) effect. Here, we report that the EPR effect was enhanced by applying nitroglycerin (NG) ointment on the skin of tumor-bearing animals. Tumors studied included breast cancer, which was induced in Sprague-Dawley rats by the chemical carcinogen 7,12-dimethylbenz[a]anthracene, and three different transplanted tumor models in mice. NG was applied on tumor or nontumorous normal skin as well. Two to three times more putative macromolecular drug (an Evans blue/albumin complex) was delivered to solid tumors with NG than without NG. We also demonstrated that NG enhanced tumor delivery with another macromolecular drug candidate, PZP, i.e. polyethylene glycol-conjugated zinc protoporphyrin IX, which inhibits heme oxygenase-1. In addition, we investigated the therapeutic effect of NG using a combination with low molecular weight anthracycline or high molecular weight PZP in mouse tumor models. NG had no apparent toxicity at the doses used, and showed significantly increased therapeutic effects in both cases. Regardless of its site of application, NG thus enhanced the delivery of the drug to tumors, and enhanced therapeutic effects.

Combination therapy of in vitro-expanded natural killer T cells and α-galactosylceramide-pulsed antigen-presenting cells in patients with recurrent head and neck carcinoma

Abstract: The aim of this clinical trial was to investigate the feasibility of intra-arterial infusion of in vitro-expanded Valpha24 natural killer T (NKT) cells combined with submucosal injection of alpha-galactosylceramide (KRN7000; alphaGalCer)-pulsed antigen-presenting cells (APC). A phase I clinical study was carried out in patients with head and neck squamous cell carcinoma (HNSCC). Patients with locally recurrent HNSCC refractory to standard therapy were eligible. Eight patients received super-selective transcatheter intra-arterial infusion of activated Valpha24 NKT cells into tumor-feeding arteries and nasal submucosal injections of alphaGalCer-pulsed APC twice with a 1-week interval. Valpha24 NKT cell-specific immune responses, safety, and antitumor effects were evaluated. The number of Valpha24 NKT cells and interferon-gamma-producing cells in peripheral blood mononuclear cells increased in seven out of eight patients enrolled. Grade 3 toxicity with a pharyngocutaneous fistula related to local tumor reduction was observed in one patient and mild adverse events with grade 1-2 symptoms occurred in seven patients. Regarding the clinical responses, three cases exhibited a partial but significant response, four were classified as stable disease, and one patient continued to develop progressive disease. The use of the intra-arterial infusion of activated Valpha24 NKT cells and the submucosal injection of alphaGalCer-pulsed APC has been shown to induce significant antitumor immunity and had beneficial clinical effects in the management of advanced HNSCC. The use of such therapeutic modalities may be helpful in the management of tumors and therefore needs to be explored in further detail. The clinical trial registration number was UMIN000000722.

Targeting the ubiquitin-proteasome system for cancer therapy

Abstract: The ubiquitin-proteasome system plays a critical role in controlling the level, activity and location of various cellular proteins. Significant progress has been made in investigating the molecular mechanisms of ubiquitination, particularly in understanding the structure of the ubiquitination machinery and identifying ubiquitin protein ligases, the primary specificity-determining enzymes. Therefore, it is now possible to target specific molecules involved in ubiquitination and proteasomal degradation to regulate many cellular processes such as signal transduction, proliferation and apoptosis. In particular, alterations in ubiquitination are observed in most, if not all, cancer cells. This is manifested by destabilization of tumor suppressors, such as p53, and overexpression of oncogenes such as c-Myc and c-Jun. In addition to the development and clinical validation of proteasome inhibitor, bortezomib, in myeloma therapy, recent studies have demonstrated that it is possible to develop inhibitors for specific ubiquitination and deubiquitination enzymes. With the help of structural studies, rational design and chemical synthesis, it is conceivable that we will be able to use 'druggable' inhibitors of the ubiquitin system to evaluate their effects in animal tumor models in the not-so-distant future.

Engineered therapeutic antibodies with improved effector functions.

Abstract: In the past decade, more than 20 therapeutic antibodies have been approved for clinical use and many others are now at the clinical and preclinical stage of development. Fragment crystallizable (Fc)-dependent antibody functions, such as antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and a long half-life, have been suggested as important clinical mechanisms of therapeutic antibodies. These functions are primarily triggered through direct interaction of the Fc domain with its corresponding receptors: FcgammaRIIIa for ADCC, C1q for CDC, and neonatal Fc receptor for prolongation of the clearance rate. However, current antibody therapy still faces the critical issues of insufficient efficacy and the high cost of the therapeutic agents. A possible solution to these issues could be to engineer antibody molecules to enhance their antitumor activity, leading to improved therapeutic outcomes and reduced doses. Here, we review advanced Fc engineering approaches for the enhancement of effector functions, some of which are now ready for evaluation of their effectiveness in clinical trials.

Gain-of-function mutations and copy number increases of Notch2 in diffuse large B-cell lymphoma

Abstract: Signaling through the Notch1 receptor has a pivotal role in early thymocyte development. Gain of Notch1 function results in the development of T-cell acute lymphoblastic leukemia in a number of mouse experimental models, and activating Notch1 mutations deregulate Notch1 signaling in the majority of human T-cell acute lymphoblastic leukemias. Notch2, another member of the Notch gene family, is preferentially expressed in mature B cells and is essential for marginal zone B-cell generation. Here, we report that 5 of 63 (approximately 8%) diffuse large B-cell lymphomas, a subtype of mature B-cell lymphomas, have Notch2 mutations. These mutations lead to partial or complete deletion of the proline-, glutamic acid-, serine- and threonine-rich (PEST) domain, or a single amino acid substitution at the C-terminus of Notch2 protein. Furthermore, high-density oligonucleotide microarray analysis revealed that some diffuse large B-cell lymphoma cases also have increased copies of the mutated Notch2 allele. In the Notch activation-sensitive luciferase reporter assay in vitro, mutant Notch2 receptors show increased activity compared with wild-type Notch2. These findings implicate Notch2 gain-of-function mutations in the pathogenesis of a subset of B-cell lymphomas, and suggest broader roles for Notch gene mutations in human cancers.

Gene expression profiling of advanced‐stage serous ovarian cancers distinguishes novel subclasses and implicates ZEB2 in tumor progression and prognosis

Abstract: To elucidate the mechanisms of rapid progression of serous ovarian cancer, gene expression profiles from 43 ovarian cancer tissues comprising eight early stage and 35 advanced stage tissues were carried out using oligonucleotide microarrays of 18 716 genes. By non-negative matrix factorization analysis using 178 genes, which were extracted as stage-specific genes, 35 advanced stage cases were classified into two subclasses with superior (n = 17) and poor (n = 18) outcome evaluated by progression-free survival (log rank test, P = 0.03). Of the 178 stage-specific genes, 112 genes were identified as showing different expression between the two subclasses. Of the 48 genes selected for biological function by gene ontology analysis or Ingenuity Pathway Analysis, five genes (ZEB2, CDH1, LTBP2, COL16A1, and ACTA2) were extracted as candidates for prognostic factors associated with progression-free survival. The relationship between high ZEB2 or low CDH1 expression and shorter progression-free survival was validated by real-time RT-PCR experiments of 37 independent advanced stage cancer samples. ZEB2 expression was negatively correlated with CDH1 expression in advanced stage samples, whereas ZEB2 knockdown in ovarian adenocarcinoma SKOV3 cells resulted in an increase in CDH1 expression. Multivariate analysis showed that high ZEB2 expression was independently associated with poor prognosis. Furthermore, the prognostic effect of E-cadherin encoded by CDH1 was verified using immunohistochemical analysis of an independent advanced stage cancer samples set (n = 74). These findings suggest that the expression of epithelial–mesenchymal transition-related genes such as ZEB2 and CDH1 may play important roles in the invasion process of advanced stage serous ovarian cancer. (Cancer Sci 2009)

Analysis of IDH1 and IDH2 mutations in Japanese glioma patients.

Abstract: A recent study reported on mutations in the active site of the isocitrate dehydrogenase 1 (IDH1) gene in several types of gliomas. All mutations detected resulted in an amino acid exchange at position 132. We analyzed the genomic region spanning wild-type R132 of IDH1 by direct sequencing in 125 glial tumors. A total of 39 IDH1 mutations were observed. Mutations of the IDH2 gene, homologous to IDH1, were often detected in gliomas without IDH1 mutations. In the present study, R172 mutation of the IDH2 gene was detected in one anaplastic astrocytoma. IDH1 or IDH2 mutations were frequently in oligodendrogliomas (67%), anaplastic astrocytomas (62%), anaplastic oligoastrocytomas (75%), anaplastic oligodendrogliomas (50%), secondary glioblastomas (67%), gangliogliomas (38%), and anaplastic gangliogliomas (60%). Primary glioblastomas were characterized by a low frequency of mutations (5%) at amino acid position 132 of IDH1. Mutations of the IDH1 or IDH2 genes were significantly associated with improved outcome in patients with anaplastic astrocytomas. Our data suggest that IDH1 or IDH2 mutation plays a role in early tumor progression of several types of glioma and might arise from a common glial precursor. The infrequency of IDH1 mutation in primary glioblastomas revealed that these subtypes are genetically distinct entities from other glial tumors.

Estrogenic G protein-coupled receptor 30 signaling is involved in regulation of endometrial carcinoma by promoting proliferation, invasion potential, and interleukin-6 secretion via the MEK/ERK mitogen-activated protein kinase pathway.

Abstract: The regulatory mechanism of endometrial carcinoma and the signal transduction pathways involved in hormone action are poorly defined It has become apparent that the G protein-coupled receptor (GPR) 30 mediates the non-genomic signaling of 17beta-estradiol (E2) Here we show that GPR30 is highly expressed in endometrial cancer tissues and cancer cell lines and positively regulates cell proliferation and invasion GPR30 expression was detected in 50 human endometrial carcinomas The transcription level of GPR30 was significantly higher in the tissue of endometrial carcinoma than in normal endometrium (P < 005) Immunohistochemical assays revealed that the positive expression rate of GPR30 protein in endometrial carcinoma tissue (35/50, 70%) was statistically higher than in normal endometrium tissue (8/30, 2667%) (chi2 = 1416, P = 00002) GPR30 overexpression was correlated with high-grade endometrial carcinoma GPR30 expression was also found in two human endometrial cancer cell lines: RL95-2 (estrogen receptor positive) and KLE (estrogen receptor negative) The roles of GPR30 in proliferative and invasive responses to E2 and G1, a non-steroidal GPR30-specific agonist, in RL95-2 and KLE cell lines were then explored We showed that E2 and G1 could initiate the MAPK/ERK mitogen-activated protein kinase pathway in both cell lines What's more, E2 and G1 promoted KLE and RL95-2 proliferation and stimulated matrix metalloproteinase production and activity via the GPR30-mediated MEK/ERK mitogen-activated protein kinase pathway, as well as increased interleukin-6 secretion These findings suggest that GPR30-mediated non-genomic signaling could play an important role in endometrial cancer

Humanized immunotoxins: A new generation of immunotoxins for targeted cancer therapy

Abstract: Chemotherapy, radiation, and surgery are the conventional treatment modalities for cancer. The success achieved with these approaches has been limited due to several factors like chemoresistance to drugs, non-specificity leading to peripheral toxicity, and non-resectable tumors. To combat these problems, the concept of targeted therapy using immunotoxins was developed. Immunotoxins are chimeric proteins with a cell-selective ligand chemically linked or genetically fused to a toxin moiety and can target cancer cells overexpressing tumor-associated antigens, membrane receptors, or carbohydrate antigens. Ligands for these receptors or monoclonal antibodies or single chain variable fragments directed against these antigens are fused with bacterial or plant toxins and are made use of as immunotoxins. Pseudomonas exotoxin, anthrax toxin, and diphtheria toxin are the commonly used bacterial toxins. Ricin, saporin, gelonin, and poke weed antiviral protein are the plant toxins utilized in immunotoxin constructs. Several such fusion proteins are in clinical trials, and denileukin difitox is a FDA-approved fusion protein. In spite of the promise shown by bacterial- and plant toxin-based chimeric proteins, their clinical application is hampered by several factors like immunogenicity of the toxin moiety and non-specific toxicity leading to vascular leak syndrome. In order to overcome these problems, a novel generation of immunotoxins in which the cytotoxic moiety is an endogenous protein of human origin like proapoptotic protein or RNase has been developed. This review summarizes the advances in this new class of fusion protein and the future directions to be explored.

B7‐H1 expression is regulated by MEK/ERK signaling pathway in anaplastic large cell lymphoma and Hodgkin lymphoma

Abstract: B7-H1 is a member of the B7 family that inhibits the function of T-cells through its receptor programmed death-1 (PD-1). We examined B7-H1 expression in anaplastic large cell lymphoma (ALCL) and Hodgkin lymphoma (HL) and found that it was constitutively expressed in both clinical samples and cell lines. In anaplastic lymphoma kinase-positive (ALK(+)) ALCL cells, B7-H1 expression was suppressed by the blocking of extracellular signal-regulated kinase (ERK) signaling and upregulated by the augmentation of ERK activity by phorbol 13-myristate 12-acetate stimulation, suggesting that B7-H1 expression is regulated by ERK signaling pathway in ALCL. ERK is one of the downstream mediators of nucleophosmin (NPM)/ALK signaling in ALK(+)ALCL, and pharmacological inhibition of ALK was shown to dephosphorylate ERK and down-regulate B7-H1. The involvement of NPM/ALK in B7-H1 expression was also demonstrated by introducing the construct into human non-ALCL lymphoid cell lines, which resulted in B7-H1 expression. In the case of HL, B7-H1 expression was shown to be dependent on the ERK and p38 mitogen-activated protein kinase (MAPK) signaling pathways. These results suggest that B7-H1 expression is controlled by common ERK signaling pathways in ALCL and HL cells. Our findings provide a potentially effective immunotherapeutic strategy for these B7-H1-expressing tumors.

Cancer stem cells and their niche.

Abstract: The unique characteristics of stem cells, specifically pluripotency and self-renewal, are critical for sustaining the lifelong functionality of organs. Stem cells reside in a special microenvironment called the niche. Stem cells interact with the niche via adhesion molecules and exchange molecular signals that maintain the specific features of stem cells. A better understanding of the nature of stem cells and their niches is expected to provide an alternative approach to the treatment of various serious diseases, including cancer, in clinical practice. It has been suggested that tumor tissue contains a type of stem cell referred to as a cancer stem cell. Interestingly, there are a number of molecules that are commonly expressed in normal and cancer stem cells that lead to different phenomena depending on the local conditions. In this review, the hematopoietic system is used as an example to show how stem cells interact with different niches. The regulatory mechanisms of two kinds of bone marrow niche, osteoblastic and vascular, are covered in this review. Furthermore, the involvement of the niche in cancer stem cell regulation, tumor invasion and metastasis, and its response to oxidative stress is described, and novel therapeutic approaches involving the interactions between cancer stem cells and their niches are addressed.

Both CD133+ and CD133- subpopulations of A549 and H446 cells contain ]cancer-initiating cells

Abstract: Tumors have been known to contain a small population of cancer stem cells that initiate tumor growth and promote tumor spreading. CD133 alone or in combination with other markers is currently being used for identification and isolation of the putative cancer stem cell population from malignant tumors. To determine whether the CD133+ cells constitute the stem cell populations of lung cancer cells A549 and H446, CD133+ and CD133− subpopulations were sorted from A549 and H446 cells by magnetic cell separation and characterized for their in vitro stem cell-like properties. Interestingly, both the CD133+ and CD133− cells displayed similar abilities of colony formation, self-renewal, proliferation, differentiation, and invasion, as well as resistance to chemotherapy drugs. Furthermore, colony formation assays showed that more than 40% of cells in both the CD133+ cells and CD133− subpopulations could form large colonies capable of regenerating the unsorted populations and forming tumors in nude mice. These results suggest that CD133 alone cannot be used as a stem cell marker for the lung cancer cells A549 and H446, and both the CD133+ and CD133− subpopulations contain similar numbers of cancer stem cells. (Cancer Sci 2009; 100: 1040–1046)

Constitutive activation of nuclear factor-κB is preferentially involved in the proliferation of basal-like subtype breast cancer cell lines

Abstract: Constitutive nuclear factor (NF)-kappaB activation is thought to be involved in survival, invasion, and metastasis in various types of cancers. However, neither the subtypes of breast cancer cells with constitutive NF-kappaB activation nor the molecular mechanisms leading to its constitutive activation have been clearly defined. Here, we quantitatively analyzed basal NF-kappaB activity in 35 human breast cancer cell lines and found that most of the cell lines with high constitutive NF-kappaB activation were categorized in the estrogen receptor negative, progesterone receptor negative, ERBB2 negative basal-like subtype, which is the most malignant form of breast cancer. Inhibition of constitutive NF-kappaB activation by expression of IkappaBalpha super-repressor reduced proliferation of the basal-like subtype cell lines. Expression levels of mRNA encoding NF-kappaB-inducing kinase (NIK) were elevated in several breast cancer cell lines, and RNA interference-mediated knockdown of NIK reduced NF-kappaB activation in a subset of the basal-like subtype cell lines with upregulated NIK expression. Taken together, these results suggest that constitutive NF-kappaB activation, partially dependent on NIK, is preferentially involved in proliferation of basal-like subtype breast cancer cells and may be a useful therapeutic target for this subtype of cancer.

Vaccination with multiple peptides derived from novel cancer‐testis antigens can induce specific T‐cell responses and clinical responses in advanced esophageal cancer

Abstract: We previously identified three novel HLA-A24-restricted epitope peptides, which were derived from three cancer-testis antigens, TTK protein kinase (TTK), lymphocyte antigen 6 complex locus K (LY6K), and insulin-like growth factor (IGF)-II mRNA binding protein 3 (IMP-3), as targets for cancer vaccination against esophageal squamous cell carcinoma (ESCC). To examine the safety, immunogenicity, and antitumor effect of vaccine treatment using a combination of these three peptides, 10 HLA-A2402-positive advanced ESCC patients who failed to standard therapy were enrolled in a phase I clinical trial. Each of the three peptides (1 mg each) was intradermally administered with 1 mL of incomplete Freund's adjuvant to the neck in three separate regions weekly for 5 weeks. The cancer vaccination therapy was well tolerated without any treatment-associated adverse events of grade 3 or 4. The TTK-, LY6K-, and/or IMP-3-specific T-cell immune responses were observed by enzyme-linked immunospot assay in peripheral blood lymphocytes obtained from nine of the 10 ESCC patients after their vaccination. The median survival time after the vaccination was 6.6 months. The vaccination could induce good clinical responses in 50% of the 10 patients. One patient experienced a complete response in hepatic metastasis lasting 7 months, one showed objective responses in all lung metastasis lesions, and three patients revealed a stable disease condition for at least 2.5 months. The cancer vaccine therapy using these three peptides demonstrated satisfactory safety and good immunogenicity as well as promising disease control rate, and therefore warrants further clinical studies.

Platelets and fibrinogen facilitate each other in protecting tumor cells from natural killer cytotoxicity

Abstract: The functions of platelets and fibrinogen in protecting tumor cells from natural killer cytotoxicity have been discussed for more than 20 years. However, their exact roles and relationships in the process are still not clear. In this study, we show that tumor cells prefer to adhere to fibrinogen than to platelets, and fibrinogen can enhance the adhesion of tumor cells to platelets. Beta3 integrin plays an important role in the adhesion of B16F10 to platelets enhanced by fibrinogen. In the presence of thrombin, fibrinogen forms dense fibrin(ogen) layers around tumor cells. Tumor cells can induce platelets to aggregate and form thrombin. Platelets, as well as thrombin, can help fibrinogen protect tumor cells from lethal contact with natural killer cells and natural killer cytotoxicity. Hirudin, a specific inhibitor of thrombin, can reverse the effect of platelets on fibrinogen in blocking natural killer cytotoxicity. Our results suggest that fibrinogen helps platelets to adhere to tumor cells, and platelets in turn promote more fibrinogen to aggregate around tumor cells by forming thrombin. They facilitate each other in protecting tumor cells from natural killer cytotoxicity.

Resveratrol and quercetin cooperate to induce senescence-like growth arrest in C6 rat glioma cells.

Abstract: Glioma is the most frequent and malignant primary human brain tumor with dismal prognosis despite multimodal therapy. Resveratrol and quercetin, two structurally related and naturally occurring polyphenols, are proposed to have anticancer effects. We report here that resveratrol and quercetin decreased the cell number in four glioma cell lines but not in rat astrocytes. Low doses of resveratrol (10 µM) or quercetin (25 µM) separately had no effect on apoptosis induction, but had a strong effect on caspase 3/7 activation when administered together. Western blot analyses showed that resveratrol (10 µM) and quercetin (25 µM) caused a reduction in phosphorylation of Akt, but this reduction was not sufficient by itself to mediate the effects of these polyphenols. Most important, resveratrol and quercetin chronically administered presented a strong synergism in inducing senescence-like growth arrest. These results suggest that the combination of polyphenols can potentialize their antitumoral activity, thereby reducing the therapeutic concentration needed for glioma treatment. (Cancer Sci 2009; 100: 1655–1662)

Ubiquitin‐mediated control of oncogene and tumor suppressor gene products

Abstract: Cellular levels of products from both oncogenes and tumor suppressor genes in normal cells need to be critically regulated to avoid malignant transformation. These products are often controlled by the ubiquitin proteasome pathway, the specific degradation mechanism in the cell. E3 ubiquitin ligases polyubiquitylate their specific substrates by collaborating with E1 and E2, and then the modified substrates are degraded in the proteasome. Mdm2 targets p53 and retinoblastoma protein, two major tumor suppressor gene products, for ubiquitin-dependent degradation. SCF(Skp2) targets other tumor suppressor gene products and CDK inhibitors such as p130, Tob1, p27(Kip1), p57(Kip2), and p21(Cip1). Therefore, both E3 ligases act like oncogene products. In contrast, degradation of several oncogene products, such as Cyclin E, Notch, c-Myc, c-Jun, and c-Myb, are mediated by SCF(Fbw7). Fbw7 is often deleted or mutated in human cancers and acts like a tumor suppressor. As well as growth factor receptors and signal transduction regulators, DNA repair-related proteins are also regulated via the ubiquitin-proteasome pathway mediated by their specific E3 ligases. The stabilization of oncogene products and enhanced degradation of tumor suppressor gene products or DNA repair proteins might be associated with carcinogenesis and malignant progression, due to defects or the abnormal expression of their E3 ligases.