Inhibition of nuclear factor-kappa B enhances the tumor growth of ovarian cancer cell line derived from a low-grade papillary serous carcinoma in p53-independent pathway.

BACKGROUND: NF-kB can function as an oncogene or tumor suppressor depending on cancer types. The role of NF-kB in low-grade serous ovarian cancer, however, has never been tested. We sought to elucidate the function of NF-kB in the low-grade serous ovarian cancer. METHODS: The ovarian cancer cell line, HOC-7, derived from a low-grade papillary serous carcinoma. Introduction of a dominant negative mutant, IkBαM, which resulted in decrease of NF-kB function in ovarian cancer cell lines. The transcription ability, tumorigenesis, cell proliferation and apoptosis were observed in derivative cell lines in comparison with parental cells. RESULTS: Western blot analysis indicated increased expression of the anti-apoptotic proteins Bcl-xL and reduced expression of the pro-apoptotic proteins Bax, Bad, and Bid in HOC-7/IĸBαM cell. Further investigations validate this conclusion in KRAS wildtype cell line SKOV3. Interesting, NF-kB can exert its pro-apoptotic effect by activating mitogen-activated protein kinase (MAPK) phosphorylation in SKOV3 ovarian cancer cell, whereas opposite changes detected in p-MEK in HOC-7 ovarian cancer cell, the same as some chemoresistant ovarian cancer cell lines. In vivo animal assay performed on BALB/athymic mice showed that injection of HOC-7 induced subcutaneous tumor growth, which was completely regressed within 7 weeks. In comparison, HOC-7/IĸBαM cells caused sustained tumor growth and abrogated tumor regression, suggesting that knock-down of NF-kB by IĸBαM promoted sustained tumor growth and delayed tumor regression in HOC-7 cells. CONCLUSION: Our results demonstrated that NF-kB may function as a tumor suppressor by facilitating regression of low grade ovarian serous carcinoma through activating pro-apoptotic pathways.

Metabolic shifts toward glutamine regulate tumor growth, invasion and bioenergetics in ovarian cancer.

Glutamine can play a critical role in cellular growth in multiple cancers. Glutamine-addicted cancer cells are dependent on glutamine for viability, and their metabolism is reprogrammed for glutamine utilization through the tricarboxylic acid (TCA) cycle. Here, we have uncovered a missing link between cancer invasiveness and glutamine dependence. Using isotope tracer and bioenergetic analysis, we found that low-invasive ovarian cancer (OVCA) cells are glutamine independent, whereas high-invasive OVCA cells are markedly glutamine dependent. Consistent with our findings, OVCA patients' microarray data suggest that glutaminolysis correlates with poor survival. Notably, the ratio of gene expression associated with glutamine anabolism versus catabolism has emerged as a novel biomarker for patient prognosis. Significantly, we found that glutamine regulates the activation of STAT3, a mediator of signaling pathways which regulates cancer hallmarks in invasive OVCA cells. Our findings suggest that a combined approach of targeting high-invasive OVCA cells by blocking glutamine's entry into the TCA cycle, along with targeting low-invasive OVCA cells by inhibiting glutamine synthesis and STAT3 may lead to potential therapeutic approaches for treating OVCAs.

Tumor stroma and differentiated cancer cells can be originated directly from polyploid giant cancer cells induced by paclitaxel.

Paclitaxel is widely used to treat cancer patients through the blocking of mitosis and result in formation of polyploidy giant cancer cells (PGCCs), which are generally believed to be nondividing cells or in mitotic catastrophe. Here, we showed that PGCCs following the treatment of paclitaxel of MCF-7 breast cancer cell line have capability to generate regular-sized progeny cells through budding. The PGCCs not only grew into well-differentiated cancer cells that formed cancer organotypic structures in vitro but also trans-differentiated into multiple tumor stromal cells including myoepithelial, endothelial and erythroid cells. PGCCs formed glandular and vessel-like cancer organotypic structures that expressed normal stem cell markers. These progeny cells generated from PGCCs showed decreased ability of proliferation, invasion and tumor growth and became more resistant to paclitaxel than parental MCF-7 cells. These results demonstrated that paclitaxel-induced PGCCs have properties of cancer stem cells that can generate both epithelial cancer cells and multilineage of stromal cells. PGCCs are not only the morphogenic determinant to tumor histogenesis and but also contribute to paclitaxel resistance.

RAS promotes tumorigenesis through genomic instability induced by imbalanced expression of Aurora-A and BRCA2 in midbody during cytokinesis.

The oncogene RAS is known to induce genomic instability, leading to cancer development; the underlying mechanism, however, remains poorly understood. To better understand how RAS functions, we measured the activity of the functionally related genes Aurora-A and BRCA2 in ovarian cancer cell lines and tumor samples containing RAS mutations. We found that Aurora-A and BRCA2 inversely controlled RAS-associated genomic instability and ovarian tumorigenesis through regulation of cytokinesis and polyploidization. Overexpression of mutated RAS ablated BRCA2 expression but induced Aurora-A accumulation at the midbody, leading to abnormal cytokinesis and ultimately chromosomal instability via polyploidy in cancer cells. RAS regulates the expression of Aurora-A and BRCA2 through dysregulated protein expression of farnesyl protein transferase ß and insulin-like growth factor binding protein 3. Our results suggest that the imbalance in expression of Aurora-A and BRCA2 regulates RAS-induced genomic instability and tumorigenesis.

CD133 expression associated with poor prognosis in ovarian cancer.

As a putative marker for cancer stem cells in human malignant tumors, including ovarian cancer, CD133 expression may define a tumor-initiating subpopulation of cells and is associated with the clinical outcome of patients. However, at this time its clinical significance in ovarian cancer remains uncertain. The aim of this study was to clarify the clinical role of CD133 expression in human ovarian cancer. Immunohistochemical staining of CD133 expression was performed in 400 ovarian carcinoma samples using tissue microarray. The associations among CD133 expression and clinical factors (diagnosis, tumor grade, cancer stage, and clinical response to chemotherapy), overall survival and disease-free survival time were analyzed. CD133 expression was found in 31% of ovarian carcinoma samples. Fisher's exact test and one-way analysis of variance suggested that CD133 expression was associated with high-grade serous carcinoma (P=0.035), late-stage disease (P<0.001), ascites level (P=0.010), and non-response to chemotherapy (P=0.023). CD133 expression was also associated with shorter overall survival time (P=0.007) and shorter disease-free survival time (P<0.001) by log-rank test. Moreover, CD133 expression was an independent predictor of shorter disease-free survival time in an unconditional logistic regression analysis with multiple covariates (P=0.024). Our results thus show that CD133 expression is a predictor of poor clinical outcome for patients with ovarian cancer, supporting the proposed link between CD133 and cancer stem cells.

Overexpression of the ß subunit of human chorionic gonadotropin promotes the transformation of human ovarian epithelial cells and ovarian tumorigenesis.

Ovarian carcinoma is the most lethal gynecologic malignancy, however underlying molecular events remain elusive. Expression of human chorionic gonadotropin ß subunit (ß-hCG) is clinically significant for both trophoblastic and nontrophoblastic cancers; however, whether ß-hCG facilitates ovarian epithelial cell tumorigenic potential remains uncharacterized. Immortalized nontumorigenic ovarian epithelial T29 and T80 cells stably overexpressing ß-hCG were examined for alterations in cell cycle and apoptotic status by flow cytometry, expression of proteins regulating cell cycle and apoptosis by Western blot, proliferation status by MTT assay, anchorage-independent colony formation, and mouse tumor formation. Immunoreactivity for ß-hCG was evaluated using mouse xenografts and on human normal ovarian, fallopian tube, endometrium, and ovarian carcinoma tissues. T29 and T80 cells overexpressing ß-hCG demonstrated significantly increased proliferation, anchorage-independent colony formation, prosurvival Bcl-X(L) protein expression, G2-checkpoint progression, elevated cyclins E/D1 and Cdk 2/4/6, and decreased apoptosis. Collectively, these transformational alterations in phenotype facilitated increased xenograft tumorigenesis (P < 0.05). Furthermore, ß-hCG immunoreactivity was elevated in malignant ovarian tumors, compared with normal epithelial expression in ovaries, fallopian tube, and endometrium (P < 0.001). Our data indicate that elevated ß-hCG transforms ovarian surface epithelial cells, facilitating proliferation, cell cycle progression, and attenuated apoptosis to promote tumorigenesis. Our results further decipher the functional role and molecular mechanism of ß-hCG in ovarian carcinoma. ß-hCG may contribute to ovarian cancer etiology, which introduces a new therapeutic intervention target for ovarian cancer.

Sequential Therapy with PARP and WEE1 Inhibitors Minimizes Toxicity while Maintaining Efficacy.

We demonstrate that concurrent administration of poly(ADP-ribose) polymerase (PARP) and WEE1 inhibitors is effective in inhibiting tumor growth but poorly tolerated. Concurrent treatment with PARP and WEE1 inhibitors induces replication stress, DNA damage, and abrogates the G2 DNA damage checkpoint in both normal and malignant cells. Following cessation of monotherapy with PARP or WEE1 inhibitors, effects of these inhibitors persist suggesting that sequential administration of PARP and WEE1 inhibitors could maintain efficacy while ameliorating toxicity. Strikingly, while sequential administration mirrored concurrent therapy in cancer cells that have high basal replication stress, low basal replication stress in normal cells protected them from DNA damage and toxicity, thus improving tolerability while preserving efficacy in ovarian cancer xenograft and patient-derived xenograft models.

Macrophage depletion through colony stimulating factor 1 receptor pathway blockade overcomes adaptive resistance to anti-VEGF therapy.

Anti-angiogenesis therapy has shown clinical benefit in patients with high-grade serous ovarian cancer (HGSC), but adaptive resistance rapidly emerges. Thus, approaches to overcome such resistance are needed. We developed the setting of adaptive resistance to anti-VEGF therapy, and performed a series of in vivo experiments in both immune competent and nude mouse models. Given the pro-angiogenic properties of tumor-associated macrophages (TAMs) and the dominant role of CSF1R in macrophage function, we added CSF1R inhibitors following emergence of adaptive resistance to anti-VEGF antibody. Mice treated with a CSF1R inhibitor (AC708) after anti-VEGF antibody resistance had little to no measurable tumor burden upon completion of the experiment while those that did not receive a CSF1R inhibitor still had abundant tumor. To mimic clinically used regimens, mice were also treated with anti-VEGF antibody and paclitaxel until resistance emerged, and then a CSF1R inhibitor was added. The addition of a CSF1R inhibitor restored response to anti-angiogenesis therapy, resulting in 83% lower tumor burden compared to treatment with anti-VEGF antibody and paclitaxel alone. Collectively, our data demonstrate that the addition of a CSF1R inhibitor to anti-VEGF therapy and taxane chemotherapy results in robust anti-tumor effects.

Coevolution of neoplastic epithelial cells and multilineage stroma via polyploid giant cells during immortalization and transformation of mullerian epithelial cells.

Stromal cells are generally considered to be derived primarily from the host's normal mesenchymal stromal cells or bone marrow. However, the origins of stromal cells have been quite controversial. To determine the role of polyploidy in tumor development, we examined the fate of normal mullerian epithelial cells during the immortalization and transformation process by tracing the expression of SV40 large T antigen. Here we show that immortalized or HRAS-transformed mullerian epithelial cells contain a subpopulation of polyploid giant cells that grow as multicellular spheroids expressing hematopoietic markers in response to treatment with CoCl2. The immortalized or transformed epithelial cells can transdifferentiate into stromal cells when transplanted into nude mice. Immunofluorescent staining revealed expression of stem cell factors OCT4, Nanog, and SOX-2 in spheroid, whereas expression of embryonic stem cell marker SSEA1 was increased in HRAS-transformed cells compared with their immortalized isogenic counterparts. These results suggest that normal mullerian epithelial cells are intrinsically highly plastic, via the formation of polyploid giant cells and activation of embryonic stem-like program, which work together to promote the coevolution of neoplastic epithelial cells and multiple lineage stromal cells.

Targeting Stromal Glutamine Synthetase in Tumors Disrupts Tumor Microenvironment-Regulated Cancer Cell Growth.

Reactive stromal cells are an integral part of tumor microenvironment (TME) and interact with cancer cells to regulate their growth. Although targeting stromal cells could be a viable therapy to regulate the communication between TME and cancer cells, identification of stromal targets that make cancer cells vulnerable has remained challenging and elusive. Here, we identify a previously unrecognized mechanism whereby metabolism of reactive stromal cells is reprogrammed through an upregulated glutamine anabolic pathway. This dysfunctional stromal metabolism confers atypical metabolic flexibility and adaptive mechanisms in stromal cells, allowing them to harness carbon and nitrogen from noncanonical sources to synthesize glutamine in nutrient-deprived conditions existing in TME. Using an orthotopic mouse model for ovarian carcinoma, we find that co-targeting glutamine synthetase in stroma and glutaminase in cancer cells reduces tumor weight, nodules, and metastasis. We present a synthetic lethal approach to target tumor stroma and cancer cells simultaneously for desirable therapeutic outcomes.

Generation of erythroid cells from fibroblasts and cancer cells in vitro and in vivo.

Bone marrow is generally considered the main source of erythroid cells. Here we report that a single hypoxia-mimic chemical, CoCl2, can increase the size of fibroblasts and cancer cells and lead to formation of polyploidy giant cells (PGCs) or polyploidy giant cancer cells (PGCCs), activation of stem cell marker expression, increased growth of normal and cancer spheroid, and lead to differentiation of the fibroblasts and epithelial cells toward erythroid lineage expressing hemoglobins both in vitro and in vivo. Immunohistochemical examination demonstrated that these cells are predominantly made of embryonic hemoglobins, with various levels of fetal and adult hemoglobins. Ectopic expression of c-Myc induced the generation of nucleated erythoid cells expressing variable levels of embryonic and fetal hemoglobins. Generation of these erythroid cells can be also observed via histological examination of other cancer cell lines and human tumor samples. These data suggest that normal and solid cancer cells can directly generate erythroid cells to obtain oxygen in response to hypoxia and may explain the ineffectiveness of conventional anti-angiogenic therapies for cancer, which are directed at endothelium-dependent vessels, and offer new targets for intervention.

iTRAQ-based proteomic analysis of polyploid giant cancer cells and budding progeny cells reveals several distinct pathways for ovarian cancer development.

Polyploid giant cancer cells (PGCCs) are a morphologically distinct subgroup of human tumor cells with increased nuclear size or multiple nuclei, but they are generally considered unimportant because they are presumed to be nondividing and thus nonviable. We have recently shown that these large cancer cells are not only viable but also can divide asymmetrically and yield progeny cancer cells with cancer stem-like properties via budding division. To further understand the molecular events involved in the regulation of PGCCs and the generation of their progeny cancer cells, we comparatively analyzed the proteomic profiles of PGCCs, PGCCs with budding daughter cells, and regular control cancer cells from the HEY and SKOv3 human ovarian cancer cell lines with and without CoCl2. We used a high-throughput iTRAQ-based proteomic methodology coupled with liquid chromatography-electrospray ionization tandem mass spectroscopy to determine the differentiated regulated proteins. We performed Western blotting and immunohistochemical analyses to validate the differences in the expression patterns of a variety of proteins between PGCCs or budding PGCCs and regular cancer cells identified by iTRAQ approach and also a selected group of proteins from the literature. The differentially regulated proteins included proteins involved in response to hypoxia, stem cell generation, chromatin remodeling, cell-cycle regulation, and invasion and metastasis. In particular, we found that HIF-1alpha and its known target STC1 are upregulated in PGCCs. In addition, we found that a panel of stem cell-regulating factors and epithelial-to-mesenchymal transition regulatory transcription factors were upregulated in budding PGCCs, whereas expression of the histone 1 family of nucleosomal linker proteins was consistently lower in PGCCs than in control cells. Thus, proteomic expression patterns provide valuable insight into the underlying mechanisms of PGCC formation and the relationship between PGCCs and cancer stem cells in patients with ovarian cancers.

VCAM1 expression correlated with tumorigenesis and poor prognosis in high grade serous ovarian cancer.

High expression of vascular cell adhesion molecule 1 (VCAM1) has been shown to be associated with several cancers although its role in ovarian cancer development is largely undefined. The purpose of this study is to investigate its role in ovarian cancer using the epithelial cells and ovarian cancer cell lines and correlate its expression with clinicopathologic parameters in ovarian cancer patients. VCAM1 expression was examined via immunohistochemical staining of 251 high grade serous carcinoma samples using tissue microarray. The expression of VCAM1 was silenced in RAS-transformed ovarian epithelial cell lines and two high grade ovarian cancer cell lines. Cell migration was analyzed in vitro and effect on tumor growth was analyzed in nude mice. High VCAM1 expression was found to be was related with response to surgery and chemotherapy drugs (P = 0.025) and elder age at diagnosis (P = 0.008). Cox regression multivariable analysis showed that VCAM1 expression in tumor cells was an independent prognostic factor. Ovarian cancer cells with VCAM1 overexpression, compared with corresponding control cells, had increased cell migration and enhanced growth of xenograft tumors in mice. Our data provide strong evidence that VCAM1 plays an important role in ovarian tumor growth, and it may be used as a prognostic factor and novel therapeutic target for ovarian cancer.

Interleukin-1ß promotes ovarian tumorigenesis through a p53/NF-κB-mediated inflammatory response in stromal fibroblasts.

Cancer has long been considered a disease that mimics an "unhealed wound," with oncogene-induced secretory activation signals from epithelial cancer cells facilitating stromal fibroblast, endothelial, and inflammatory cell participation in tumor progression. However, the underlying mechanisms that orchestrate cooperative interaction between malignant epithelium and the stroma remain largely unknown. Here, we identified interleukin-1ß (IL-1ß) as a stromal-acting chemokine secreted by ovarian cancer cells, which suppresses p53 protein expression in cancer-associated fibroblasts (CAFs). Elevated expression of IL-1ß and cognate receptor IL-1R1 in ovarian cancer epithelial cells and CAFs independently predicted reduced overall patient survival, as did repressed nuclear p53 in ovarian CAFs. Knockdown of p53 expression in ovarian fibroblasts significantly enhanced the expression and secretion of chemokines IL-8, growth regulated oncogene-alpha (GRO-α), IL-6, IL-1ß, and vascular endothelial growth factor (VEGF), significantly increased in vivo mouse xenograft ovarian cancer tumor growth, and was entirely dependent on interaction with, and transcriptional up-regulation of, nuclear factor-kappaB (NF-κB) p65. Our results have uncovered a previously unrecognized circuit whereby epithelial cancer cells use IL-1ß as a communication factor instructing stromal fibroblasts through p53 to generate a protumorigenic inflammatory microenvironment. Attenuation of p53 protein expression in stromal fibroblasts generates critical protumorigenic functionality, reminiscent of the role that oncogenic p53 mutations play in cancer cells. These findings implicate CAFs as an important target for blocking inflammation in the tumor microenvironment and reducing tumor growth.

Sex-determining region Y-box 2 expression predicts poor prognosis in human ovarian carcinoma.

Sex-determining region Y-box 2 is proposed to be a key transcription factor in embryonic stem cells. The known roles of sex-determining region Y-box 2 in development and cell differentiation suggest that it is relevant to the aberrant growth of tumor cells. Thus, sex-determining region Y-box 2 may play an important role in tumor progression. However, its clinical significance in human ovarian carcinoma has been uncertain until recently. The aim of the present study was to clarify the clinical role of sex-determining region Y-box 2 expression in ovarian carcinoma. Immunohistochemical staining of 540 human ovarian carcinoma samples for sex-determining region Y-box 2 was performed using tissue microarray. The associations among sex-determining region Y-box 2 expression and clinical factors (diagnosis, tumor grade, International Federation of Gynecology and Obstetrics stage, and response to chemotherapy), overall survival, and disease-free survival were analyzed. We observed sex-determining region Y-box 2 expression in 15% of the ovarian carcinoma samples. Use of the Fisher exact test suggested that sex-determining region Y-box 2 expression was associated with high-grade carcinoma (P = .009), especially high-grade serous carcinoma (P = .048); International Federation of Gynecology and Obstetrics stage (II-IV; P = .005); and malignant mixed müllerian tumors (P = .048). Sex-determining region Y-box 2 expression was also associated with decreased disease-free survival durations (P = .035; log-rank test). Our results showed that sex-determining region Y-box 2 expression may be a potential marker related to tumor recurrence, as implicated by its role in cancer stem cells.

Paclitaxel inhibits ovarian tumor growth by inducing epithelial cancer cells to benign fibroblast-like cells.

Paclitaxel is commonly used to treat multiple human malignancies, but its mechanism of action is still poorly defined. Human ovarian cancer SKOV3 cells (parental SKOV3) were treated with paclitaxel (1µM) for 2days, and the morphologic changes in the cells were monitored for more than 4months. Parental SKOV3 underwent a markedly morphologic transition from the epithelial to fibroblast-like phenotype following treatment with paclitaxel; the resulting cells were designated as SKOV3-P. The SKOV3-P cells' proliferative ability was assessed via a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. The molecular characteristics of these cells were assessed via immunocytochemical staining and Western blot analysis. Their invasiveness and tumor formation ability was evaluated via wound-scratch and colony formation assays. The tumorigenicity of SKOV3-P cells was assessed in vivo after subcutaneous injection of tumor cells between injections of parental and paclitaxel-treated cells in nude mice. SKOV3-P cells have decreased the proliferation and invasion ability, decreased colony-forming ability when cultured in Matrigel and lost their tumor formation as compared with parental SKOV3 cells when injected in nude mice. SKOV3-P cells have decreased expression of E-cadherin, cytokeratin, Snail, PI3K, and P-Akt-Ser473, and increased expression of fibronectin, vimentin, Slug, P27, and PTEN. These results demonstrated that paclitaxel can inhibit tumor growth by inducing ovarian cancer epithelial cells toward a benign fibroblast-like phenotype through dysregulation of previously known pathways involved in the regulation of epithelial to mesenchymal transition (EMT), which may represent a novel mechanism for paclitaxel-induced tumor suppression.

Mucinous adenocarcinoma developed from human fallopian tube epithelial cells through defined genetic modifications.

Recent studies have suggested that some ovarian and pelvic serous carcinomas could originate from the fimbriated end of the distal fallopian tube. To test this hypothesis, we immortalized a normal human fallopian tube epithelial (FTE) cell line by using retrovirus-mediated overexpression of the early region of the SV40 T/t antigens and the human telomerase reverse transcriptase subunit (hTERT). These immortalized FTEs were then transformed by ectopic expression of oncogenic human HRAS (V12) . Tumorigenicity of the immortalized and/or transformed cells was subsequently tested by anchorage-independence growth assay and inoculation into nude mice via subcutaneous and intraperitoneal injection. As expected, the HRAS (V12) -transformed FTEs produced tumors through both subcutaneous and intraperitoneal injections, whereas no tumor growth was observed in immortalized FTEs. Unexpectedly, histopathological examination of tumors resulting from subcutaneous as well as intraperitoneal injections revealed largely poorly differentiated mucinous adenocarcinoma mixed with undifferentiated carcinoma. The tumor implants invaded extensively to the liver, colon, spleen, omentum, adrenal gland and renal capsule. Immunohistochemical staining of tumor cells showed positive staining for the epithelial cell markers cytokeratin AE1/AE3 and Müllerian lineage marker PAX8. Our study demonstrates that FTEs can generate poorly differentiated mucinous adenocarcinoma mixed with undifferentiated carcinoma through genetic modifications. Thus, we provide the first experimental evidence that fimbrial epithelial cells of the fallopian tube could be a potential source of ovarian mucinous adenocarcinoma.

The oncogenic gene fusion TMPRSS2: ERG is not a diagnostic or prognostic marker for ovarian cancer.

TMPRSS2:ERG is a gene fusion resulting from the chromosomal rearrangement of the androgen-regulated TMPRSS2 gene and the ETS transcription factor ERG, leading to the over-expression of the oncogenic molecule ERG. This gene rearrangement has been found in approximately half of all prostate cancers and ERG overexpression is considered as a novel diagnostic marker for prostate carcinoma. However, little is known about the role of the TMPRSS2:ERG gene fusion in ovarian cancer. The purpose of this study was to test ERG expression in ovarian cancer and its potential as a diagnostic marker for ovarian carcinoma progression. A tissue microarray containing 180 ovarian cancer tissues of various pathological types and grades were examined by immunohistochemical analysis for expression of ERG. We also used 40 prostate carcinoma tissues and 40 normal tissues for comparison in parallel experiments. ERG-positive expression was detected in 40% of the prostate tumor cancer, as well as in internal positive control endothelial cells, confirming over-expression of ERG in prostate cancer at relatively the same rate observed by others. In contrast, all of the ovarian tumor patient tissues of varying histologic types were ERG-negative, despite some positivity in endothelial cells. These results suggest that the oncogenic gene fusion TMPRSS2:ERG does not occur in ovarian cancer relative to prostate cancer. Therefore, development of ERG expression profile would not be a useful diagnostic or prognostic marker for ovarian cancer patient screening.

The biphasic role of NF-kappaB in progression and chemoresistance of ovarian cancer.

PURPOSE: NF-κB is a transcription factor known to promote tumorigenesis. However, NF-κB is also known to be proapoptotic and may potentially function as a tumor suppressor, although such a functional role has not been extensively investigated in human cancer. EXPERIMENTAL DESIGN: A dominant-negative mutant of IκBα with mutations at S32A and S36A was used to inhibit the function of NF-κB in ovarian cancer cell lines. The transcription ability, tumorigenesis, apoptosis, and drug sensitivity were examined in derivative cell lines in comparison with parental cells. We also analyzed the association of nuclear expression of NF-κB p65 with patient survival in an ovarian cancer tissue array. RESULTS: We show that NF-κB functions as a tumor suppressor in four ovarian cancer cell lines, but it functions as an oncogene in their aggressive chemoresistant isogenic variants. NF-κB can exert its proapoptotic or antiapoptotic effect by activating or repressing mitogen-activated protein kinase (MAPK) phosphorylation in parental or aggressive chemoresistant variant cell lines. We also show that the nuclear accumulation of p65 in epithelial cancer tissue is associated with a good response to chemotherapy and can predict longer overall survival for patients with ovarian cancer. CONCLUSIONS: Our data provide strong evidence that NF-κB can function as a biphasic regulator, either suppressing or enhancing ovarian cancer growth through the regulation of MAPK and cellular apoptosis.

Stanniocalcin 1 and ovarian tumorigenesis.

BACKGROUND: Stanniocalcin 1 (STC1) is a secreted glycoprotein hormone. High expression of STC1 has been associated with several cancers including ovarian cancer, but its role in the development of ovarian cancer is not clear. METHODS: We used five human ovarian epithelial cancer cell lines (OVCA420, OVCA432, OVCA433, SKOV3, and HEY), immortalized human ovarian surface epithelial cells (T29 and T80), ovarian cancer tissues from 342 patients, serum from 73 ovarian cancer patients and from58 control subjects, and 116 mice, with six or eight per group. Protein expression was assessed. Cells overexpressing STC1 protein were generated by ectopic expression of human STC1 cDNA. STC1 expression was silenced by using small interfering RNA against STC1. Cell proliferation, migration, colony formation, and apoptosis were assessed. Xenograft tumor growth in mice was studied. Neutralizing anti-STC1 antibody was used to inhibit STC1 function. All statistical tests were two-sided. RESULTS: STC1 protein expression was higher in all human ovarian cancer cell lines examined than in immortalized human ovarian epithelial cell lines, higher in ovarian cancer tissue than in normal ovarian tissue (P < .001), and higher in serum from ovarian cancer patients than from control subjects (P = .021). Ovarian cancer cells with STC1 overexpression, compared with corresponding control cells, had increased cell proliferation, migration, and colony formation in cell culture and increased growth of xenograft tumors in mice. These activities in normal or malignant ovarian cells with STC1 overexpression, compared with control cells, were also accompanied by increased expression of cell cycle regulatory proteins and antiapoptotic proteins but decreased cleavage of several caspases. Within 24 hours of treatment, apoptosis in cultures of HEY ovarian cancer cells treated with neutralizing anti-STC1 monoclonal antibody was higher (17.3% apoptotic cells) than that in cultures treated with mouse IgG control cells (4.4%) (12.9% difference, 95% confidence interval = 11.6% to 14.2%). CONCLUSIONS: STC1 protein may be involved in ovarian tumorigenesis.