Epithelial-mesenchymal transition in ovarian carcinoma

EMT-Inducing Molecular Factors in Gynecological Cancers

Gynecologic cancers are the unregulated growth of neoplastic cells that arise in the cervix, ovaries, fallopian tubes, uterus, vagina, and vulva. Although gynecologic cancers are characterized by different signs and symptoms, studies have shown that they share common risk factors, such as smoking, obesity, age, exposure to certain chemicals, infection with human immunodeficiency virus (HIV), and infection with human papilloma virus (HPV). Despite recent advancements in the preventative, diagnostic, and therapeutic interventions for gynecologic cancers, many patients still die as a result of metastasis and recurrence. Since mounting evidence indicates that the epithelial-mesenchymal transition (EMT) process plays an essential role in metastatic relapse of cancer, understanding the molecular aberrations responsible for the EMT and its underlying signaling should be given high priority in order to reduce cancer morbidity and mortality.

Epithelial-mesenchymal status renders differential responses to cisplatin in ovarian cancer

Chemoresistance to platinums, such as cisplatin, is of critical concern in the treatment of ovarian cancer. Recent evidence has linked epithelial-mesenchymal transition (EMT) as a contributing mechanism. The current study explored the connection between cellular responses to cisplatin and EMT in ovarian cancer. Expression microarrays were utilized to estimate the EMT status as a binary phenotype, and the transcriptional responses of 46 ovarian cancer cell lines to cisplatin were measured at dosages equivalent to 50% growth inhibition. Phenotypic responses to cisplatin were quantified with respect to cell number, proliferation rate and apoptosis, and then compared with the epithelial or mesenchymal status. Ovarian cancer cell lines with an epithelial status exhibited higher resistance to cisplatin treatment in the MTS assay than those with a mesenchymal status. Pathway analyses revealed the induction of G1/S- and S-phase genes (P=0.001) and the activation of multiple NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) downstream genes (P=0.0016) by cisplatin selectively in epithelial-like cell lines. BrdU incorporation and Caspase-3/7 release assays confirmed impaired apoptosis in epithelial-like ovarian cancer cells. In clinical samples, we observed resistance to single platinum treatment and the selective activation of the NF-κB pathway by platinum in ovarian cancers with an epithelial status. Overall, our results suggest that, in epithelial-like ovarian cancer cells, NF-κB activation by cisplatin may lead to defective apoptosis, preferential proliferation arrest and a consequential decreased sensitivity to cisplatin.

Comparative Analysis of Differentially Expressed miRNAs and their Downstream mRNAs in Ovarian Cancer and its Associated Endometriosis

Objective

There is an increased risk of developing ovarian cancer (OC) in patients with endometriosis. Hence, development of new biomarkers may provide a positive clinical outcome for early detection. MicroRNAs (miRNAs) are small non-coding RNAs that play an important role in biological and pathological process and are currently used as diagnostic and prognostic markers in various cancers. In the current study, we assessed the differential expression of miRNAs from 19 paired ovarian cancer and its associated endometriosis tissue samples. In addition we also analyzed the downstream targets of those miRNAs.

Methods

Nineteen paired cases of ovarian cancer and endometriosis foci were identified by a gynecologic pathologist and macro-dissected. The total RNAs were extracted and subjected to comprehensive miRNA profiling from the pooled samples of these two different entities using microarray analysis. Later, the abnormal expressions of few selected miRNAs were validated in individual cases by quantitative real-time PCR (qRT-PCR). Ingenuity pathway analysis revealed target mRNAs which were validated by qRT-PCR.

Results

The miRNA profiling identified deregulation of greater than 1156 miRNAs in OC, of which the top seven were further validated by qRT-PCR. The expression of miR-1, miR-133a, and miR-451 were reduced significantly (p<0.0001) in the OC patients compared to its associated endometriosis. In contrast, the expression of miR-141, miR-200a, miR-200c, and miR-3613 were elevated significantly (p<0.05) in most of the OC patients. Furthermore, among the downstream mRNAs of these miRNAs, the level of PTEN expression was significantly (p<0.05) reduced in OC compared to endometriosis while no significant difference was observed in NF-κB expression.

Conclusion

The expression of miRNAs and mRNAs in OC were significantly different compared to its concurrent endometriosis. These differential expressed miRNAs may serve as potential diagnostic and prognostic biomarkers for OC associated with endometriosis.

The clinical role of epithelial-mesenchymal transition and stem cell markers in advanced-stage ovarian serous carcinoma effusions

We recently identified gene signatures that allow classification of ovarian carcinoma into 5 distinct clinically relevant groups. In the present study, we investigated the clinical role of 10 protein products of the discriminating genes, with focus on epithelial-mesenchymal transition and stem cell markers. Expression of E-cadherin, N-cadherin, P-cadherin, Zeb1, HMGA2, Rab25, CD24, NCAM (CD56), Sox11, and vimentin was assessed in 100 advanced-stage (International Federation of Gynecology and Obstetrics stages III-IV) serous ovarian carcinoma effusions using immunohistochemistry. Results were analyzed for association with clinicopathological parameters, including chemotherapy response, and survival. All 10 proteins were frequently expressed in carcinoma cells. HMGA2 expression was related to older age (P = .015). HMGA2 and NCAM expression was related to stage III disease (P = .011 and P = .023, respectively), and NCAM was overexpressed in peritoneal compared with pleural effusions (P = .001). Vimentin and Zeb1 expression was significantly related to poor chemotherapy response at diagnosis (P = .005 and P = .017, respectively). The associations between NCAM and peritoneal localization and of vimentin and poor chemoresponse were retained after Bonferroni correction. NCAM expression was associated with a trend for shorter overall survival in univariate survival analysis (P = .187), but emerged as an independent prognosticator in Cox multivariate analysis (P = .042). This study identifies vimentin and Zeb1 as markers of poor chemoresponse in metastatic serous ovarian carcinoma effusions and suggests NCAM as potential prognostic marker in metastatic disease. The generally limited prognostic role of the studied markers emphasizes the difficulty in applying data obtained in studies of primary ovarian carcinomas to analyses of ovarian carcinoma effusions, reflecting the unique biology of the latter.

Overexpression of c-Met increases the tumor invasion of human prostate LNCaP cancer cells in vitro and in vivo

c-Met is a transmembrane tyrosine kinase receptor that may be activated by hepatocyte growth factor, an inducer of epithelial-mesenchymal transition (EMT), to regulate the associated downstream gene expression. This process is critical to cell migration in normal and pathological conditions. In the present study, the function of c-Met in the process of EMT was investigated in prostate cancer. Initially, a c-Met stable expression cell line was constructed using EMT- and c-Met-negative LNCaP prostate cancer cells. Following the identification of c-Met in the transfected cells, the changes in EMT, phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated kinase pathway biomarkers were determined by western blot analysis. MTT, soft agar and Transwell assays, and xenograft studies were used to investigate the effects of c-Met on the proliferation, migration and tumorigenicity of LNCaP cells. The results of the present study revealed downregulation of E-cadherin and upregulation of vimentin in LNCaP-Met cells. The results demonstrated that c-Met enhanced proliferation, migration and tumorigenicity capacity when compared with LNCaP and LNCaP-pcDNA3.1 cells. Furthermore, these EMT-like changes were mediated via the PI3K and mitogen-activated protein kinase signaling pathways. The present study clearly demonstrates a crucial function for c-Met in EMT development in prostate cancer. c-Met-targeted treatment may be an effective adjuvant therapy for improving survival rates in patients with prostate cancer.

Ascites-induced shift along epithelial-mesenchymal spectrum in ovarian cancer cells: enhancement of their invasive behavior partly dependant on αv integrins

At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence. The presence of ascites, which acts as a dynamic reservoir of active molecules and cellular components, correlates with the OC peritoneal metastasis and is associated with poor prognosis. Since epithelial-mesenchymal transition (EMT) is involved in different phases of OC progression, we have investigated the effect of the unique ascitic tumor microenvironment on the EMT status and the behavior of OC cells. The exposure of three OC cell lines to ascites leads to changes in cellular morphologies. Within ascites, OC cells harboring an initial intermediate epithelial phenotype are characterized by marked dislocation of epithelial markers (E-cadherin, ZO-1 staining) while OC cells initially harboring an intermediate mesenchymal phenotype strengthen their mesenchymal markers (N-cadherin, vimentin). Ascites differentially triggers a dissemination phenotype related to the initial cell features by either allowing the proliferation and the formation of spheroids and the extension of colonies for cells that present an initial epithelial intermediate phenotype, or favoring the migration of cells with a mesenchymal intermediate phenotype. In an ascitic microenvironment, a redeployment of αv integrins into cells was observed and the ascites-induced accentuation of the two different invasive phenotypes (i.e. spheroids formation or migration) was shown to involve αv integrins. Thus, ascites induces a shift toward an unstable intermediate state of the epithelial-mesenchymal spectrum and confers a more aggressive cell behavior that takes on a different pathway based on the initial epithelial-mesenchymal cell features.

Epithelial-mesenchymal status renders differential responses to cisplatin in ovarian cancer

Chemoresistance to platinums, such as cisplatin, is of critical concern in the treatment of ovarian cancer. Recent evidence has linked epithelial-mesenchymal transition (EMT) as a contributing mechanism. The current study explored the connection between cellular responses to cisplatin and EMT in ovarian cancer. Expression microarrays were utilized to estimate the EMT status as a binary phenotype, and the transcriptional responses of 46 ovarian cancer cell lines to cisplatin were measured at dosages equivalent to 50% growth inhibition. Phenotypic responses to cisplatin were quantified with respect to cell number, proliferation rate and apoptosis, and then compared with the epithelial or mesenchymal status. Ovarian cancer cell lines with an epithelial status exhibited higher resistance to cisplatin treatment in the MTS assay than those with a mesenchymal status. Pathway analyses revealed the induction of G1/S- and S-phase genes (P=0.001) and the activation of multiple NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) downstream genes (P=0.0016) by cisplatin selectively in epithelial-like cell lines. BrdU incorporation and Caspase-3/7 release assays confirmed impaired apoptosis in epithelial-like ovarian cancer cells. In clinical samples, we observed resistance to single platinum treatment and the selective activation of the NF-κB pathway by platinum in ovarian cancers with an epithelial status. Overall, our results suggest that, in epithelial-like ovarian cancer cells, NF-κB activation by cisplatin may lead to defective apoptosis, preferential proliferation arrest and a consequential decreased sensitivity to cisplatin.

Immunohistological insight into the correlation between neuropilin-1 and epithelial-mesenchymal transition markers in epithelial ovarian cancer

The mechanism by which neuropilin-1 (NRP-1) induces malignancy in Epithelial Ovarian Cancer (EOC) is still unknown. This study is the first to demonstrate the relationship between NRP-1 expression and EMT markers vimentin, N-cadherin, E-cadherin and Slug. We used tissue microarrays containing the three main subtypes of EOC tumors: serous, mucinous cystadenocarcinoma and endometrioid adenocarcinoma and representative cases retrieved from our pathology archives. Immunohistochemistry was performed to detect the expression levels and location of NRP-1 and the aforementioned EMT proteins. NRP-1 was mainly expressed on cancer cells but not in normal ovarian surface epithelium (OSE). The Immunoreactive Scoring (IRS) values revealed that the expression of NRP-1, Slug and E-cadherin in the malignant subtypes of ovarian tissues was significantly higher (5.18 ± 0.64, 4.84 ± 0.7, 4.98 ± 0.68, respectively) than their expression in the normal and benign tissues (1.04 ± 0.29, 0.84 ± 0.68, 1.71 ± 0.66, respectively), with no significant differences among the studied subtypes. Vimentin was expressed in the cancer cell component of 43% of tumors and it was exclusively localized in the stroma of all mucinous tumors. The Spearman's rho value indicated that NRP-1 is positively related to the EMT markers E-cadherin and Slug. This notion might indicate that NRP-1 is a partner in the EMT process in EOC tumors.

Mesenchymal gene program-expressing ovarian cancer spheroids exhibit enhanced mesothelial clearance

Metastatic dissemination of ovarian tumors involves the invasion of tumor cell clusters into the mesothelial cell lining of peritoneal cavity organs; however, the tumor-specific factors that allow ovarian cancer cells to spread are unclear. We used an in vitro assay that models the initial step of ovarian cancer metastasis, clearance of the mesothelial cell layer, to examine the clearance ability of a large panel of both established and primary ovarian tumor cells. Comparison of the gene and protein expression profiles of clearance-competent and clearance-incompetent cells revealed that mesenchymal genes are enriched in tumor populations that display strong clearance activity, while epithelial genes are enriched in those with weak or undetectable activity. Overexpression of transcription factors SNAI1, TWIST1, and ZEB1, which regulate the epithelial-to-mesenchymal transition (EMT), promoted mesothelial clearance in cell lines with weak activity, while knockdown of the EMT-regulatory transcription factors TWIST1 and ZEB1 attenuated mesothelial clearance in ovarian cancer cell lines with strong activity. These findings provide important insights into the mechanisms associated with metastatic progression of ovarian cancer and suggest that inhibiting pathways that drive mesenchymal programs may suppress tumor cell invasion of peritoneal tissues.

Overexpressed FOXC2 in ovarian cancer enhances the epithelial-to-mesenchymal transition and invasion of ovarian cancer cells

Ovarian cancer is a highly invasive and metastatic disease with poor prognosis, particularly if this disease is diagnosed at an advanced stage, which is often the case. Researchers have argued that ovarian cancer cells that have undergone epithelial‑to‑mesenchymal transition (EMT) acquire aggressive malignant properties; however, the relevant molecular mechanisms in this setting are poorly understood. In cancer cases, the transcription factor forkhead box protein C2 (FOXC2) has been detected, but the function of this factor in ovarian cancer tumorigenesis remains unclear. In the present study, FOXC2 was overexpressed in invasive ovarian cancer cell lines and tissues. The invasive potential of ovarian cancer cells was significantly increased by ectopic FOXC2 expression but it was significantly decreased by RNA interference targeting FOXC2. E‑cadherin and vimentin expression levels were modulated by FOXC2. These results indicated that FOXC2 was required for the maintenance of the mesenchymal phenotype after TGF‑β1 induced EMT in human ovarian cancer cells. Thus, FOXC2 or its associated gene expression program may provide an effective target for anti-EMT-based therapies. These therapies can then be performed to treat invasive ovarian tumor.

Global miRNA expression analysis of serous and clear cell ovarian carcinomas identifies differentially expressed miRNAs including miR-200c-3p as a prognostic marker

BACKGROUND

Improved insight into the molecular characteristics of the different ovarian cancer subgroups is needed for developing a more individualized and optimized treatment regimen. The aim of this study was to a) identify differentially expressed miRNAs in high-grade serous ovarian carcinoma (HGSC), clear cell ovarian carcinoma (CCC) and ovarian surface epithelium (OSE), b) evaluate selected miRNAs for association with clinical parameters including survival and c) map miRNA-mRNA interactions.

METHODS

Differences in miRNA expression between HGSC, CCC and OSE were analyzed by global miRNA expression profiling (Affymetrix GeneChip miRNA 2.0 Arrays, n = 12, 9 and 9, respectively), validated by RT-qPCR (n = 35, 19 and 9, respectively), and evaluated for associations with clinical parameters. For HGSC, differentially expressed miRNAs were linked to differentially expressed mRNAs identified previously.

RESULTS

Differentially expressed miRNAs (n = 78) between HGSC, CCC and OSE were identified (FDR < 0.01%), of which 18 were validated (p < 0.01) using RT-qPCR in an extended cohort. Compared with OSE, miR-205-5p was the most overexpressed miRNA in HGSC. miR-200 family members and miR-182-5p were the most overexpressed in HGSC and CCC compared with OSE, whereas miR-383 was the most underexpressed. miR-205-5p and miR-200 members target epithelial-mesenchymal transition (EMT) regulators, apparently being important in tumor progression. miR-509-3-5p, miR-509-5p, miR-509-3p and miR-510 were among the strongest differentiators between HGSC and CCC, all being significantly overexpressed in CCC compared with HGSC. High miR-200c-3p expression was associated with poor progression-free (p = 0.031) and overall (p = 0.026) survival in HGSC patients. Interacting miRNA and mRNA targets, including those of a TP53-related pathway presented previously, were identified in HGSC.

CONCLUSIONS

Several miRNAs differentially expressed between HGSC, CCC and OSE have been identified, suggesting a carcinogenetic role for these miRNAs. miR-200 family members, targeting EMT drivers, were mostly overexpressed in both subgroups, among which miR-200c-3p was associated with survival in HGSC patients. A set of miRNAs differentiates CCC from HGSC, of which miR-509-3-5p and miR-509-5p are the strongest classifiers. Several interactions between miRNAs and mRNAs in HGSC were mapped.

Role of long non-coding RNA HULC in cell proliferation, apoptosis and tumor metastasis of gastric cancer: a clinical and in vitro investigation

Long non-coding RNAs (lncRNAs) are emerging as key molecules in human cancer. Highly upregulated in liver cancer (HULC), an lncRNA, has recently been revealed to be involved in hepatocellular carcinoma development and progression. It remains unclear, however, whether HULC plays an oncogenic role in human gastric cancer (GC). In the present study, we demonstrated that HULC was significantly overexpressed in GC cell lines and GC tissues compared with normal controls, and this overexpression was correlated with lymph node metastasis, distant metastasis and advanced tumor node metastasis stages. In addition, a receiver operating characteristic (ROC) curve was constructed to evaluate the diagnostic values and the area under the ROC curve of HULC was up to 0.769. To uncover its functional importance, gain- and loss-of-function studies were performed to evaluate the effect of HULC on cell proliferation, apoptosis and invasion in vitro. Overexpression of HULC promoted proliferation and invasion and inhibited cell apoptosis in SGC7901 cells, while knockdown of HULC in SGC7901 cells showed the opposite effect. Mechanistically, we discovered that overexpression of HULC could induce patterns of autophagy in SGC7901 cells; more importantly, autophagy inhibition increased overexpression of HULC cell apoptosis. We also determined that silencing of HULC effectively reversed the epithelial-to-mesenchymal transition (EMT) phenotype. In summary, our results suggest that HULC may play an important role in the growth and tumorigenesis of human GC, which provides us with a new biomarker in GC and perhaps a potential target for GC prevention, diagnosis and therapeutic treatment.

An EMT spectrum defines an anoikis-resistant and spheroidogenic intermediate mesenchymal state that is sensitive to e-cadherin restoration by a src-kinase inhibitor, saracatinib (AZD0530)

The phenotypic transformation of well-differentiated epithelial carcinoma into a mesenchymal-like state provides cancer cells with the ability to disseminate locally and to metastasise. Different degrees of epithelial-mesenchymal transition (EMT) have been found to occur in carcinomas from breast, colon and ovarian carcinoma (OC), among others. Numerous studies have focused on bona fide epithelial and mesenchymal states but rarely on intermediate states. In this study, we describe a model system for appraising the spectrum of EMT using 43 well-characterised OC cell lines. Phenotypic EMT characterisation reveals four subgroups: Epithelial, Intermediate E, Intermediate M and Mesenchymal, which represent different epithelial-mesenchymal compositions along the EMT spectrum. In cell-based EMT-related functional studies, OC cells harbouring an Intermediate M phenotype are characterised by high N-cadherin and ZEB1 expression and low E-cadherin and ERBB3/HER3 expression and are more anoikis-resistant and spheroidogenic. A specific Src-kinase inhibitor, Saracatinib (AZD0530), restores E-cadherin expression in Intermediate M cells in in vitro and in vivo models and abrogates spheroidogenesis. We show how a 33-gene EMT Signature can sub-classify an OC cohort into four EMT States correlating with progression-free survival (PFS). We conclude that the characterisation of intermediate EMT states provides a new approach to better define EMT. The concept of the EMT Spectrum allows the utilisation of EMT genes as predictive markers and the design and application of therapeutic targets for reversing EMT in a selective subgroup of patients.

Regulation of the Epithelial-Mesenchymal Transition by Claudin-3 and Claudin-4

The mechanisms that control intracellular adhesion are central to the process of invasion and metastasis. Claudin-3 (CLDN3) and claudin-4 (CLDN4) are major structural molecules of the tight junctions that link epithelial cells. Our prior work has demonstrated that knockdown of the expression of either CLDN3 or CLDN4 produces marked changes in the phenotype of ovarian carcinoma cells including increases in growth rate in vivo, migration, invasion, metastasis, and drug resistance, similar to those produced by the epithelial-to-mesenchymal transition (EMT). We postulated that these changes may result from the ability of CLDN3 or CLDN4 to suppress EMT. In this study we found that knockdown of either CLDN3 or CLDN4 increased cell size and resulted in flattened morphology. While knockdown of CLDN3 or CLDN4 did not alter the expression of vimentin, it significantly down-regulated the level of E-cadherin and up-regulated N-cadherin expression. Conversely, over-expression of CLDN3 or CLDN4 in a cell line that does not express endogenous CLDN3 or CLDN4 decreased N-cadherin expression. Re-expression of E-cadherin in the CLDN3 or CLDN4 knockdown cells reduced migration, invasion and tumor growth in vivo. Loss of either CLDN3 or CLDN4 resulted in activation of the PI3K pathway as evidenced by increased Akt phosphorylation, elevated cellular PIP3 content and PI3K activity as well as up-regulation of the mRNA and protein levels of the transcription factor Twist. Taken together, these findings suggest that CLDN3 and CLDN4 function to sustain an epithelial phenotype and that their loss promotes EMT.

Epithelial-mesenchymal transition in carcinomas of the female genital tract

Invasion is a defining feature of malignancy, but the mechanisms of invasion in many common cancers, including gynaecological malignancies, remain unclear. However, it has been proposed that malignant cells may usurp a normal embryological process, epithelial-mesenchymal transition (EMT), as a means of acquiring migratory capacity. The synergistic role of the tumour microenvironment in EMT induction has also been explored and helps to explain the spatially restricted distribution of EMT at the deep tumour margin (invasive front). Furthermore, tumour cells undergoing EMT may acquire cancer stem cell characteristics, and this may be relevant to the entire metastatic process and to tumour recurrence and treatment failure. Nevertheless, doubts persist regarding the role of EMT in malignant progression in vivo, partly because few studies have correlated molecular and histological alterations in clinical pathology specimens. In the current review we summarize the evidence for EMT in the common gynaecological epithelial malignancies, and discuss the morphological and immunohistochemical changes occurring at the invasive tumour front that may represent EMT-like processes. The possibility that carcinosarcomas represent a variant type of EMT with 'fixed' mesenchymal differentiation is also considered. Diagnostic histopathologists are ideally placed to critically evaluate the role of EMT in gynaecological and other types of malignancy.

Notch3 induces epithelial-mesenchymal transition and attenuates carboplatin-induced apoptosis in ovarian cancer cells

OBJECTIVE

Notch3 is implicated in chemoresistance of ovarian cancer, yet the molecular mechanism underlying Notch3-mediated drug resistance remains to be elucidated. Here, we investigated the role of Notch3 in carboplatin-induced apoptosis in ovarian cancer cells.

METHODS

Ovarian cancer cell line OVCA429 cells were stably transduced with an empty vector or a retroviral vector expressing the Notch3 intracellular domain (NICD3, the constitutively active form of Notch3) to generate OVCA429/vector and OVCA429/NICD3 cells. Epithelial-mesenchymal transition (EMT) was determined by morphological change and expression of the EMT markers. Carboplatin-induced cytotoxicity was determined by the neutral red uptake assay. Apoptosis was determined by Annexin V staining and Western blotting. Carboplatin-induced phosphorylation of extracellular signal-regulated kinase (ERK) was identified by a phospho-kinase array and confirmed by Western blotting.

RESULTS

Activation of Notch3 in OVCA429 cells causes a spindle and fibroblast-like morphology, induces the expression of smooth muscle α-actin, Slug and Snail, but decreases the expression of E-cadherin, indicating that Notch3 activation induces EMT in OVCA429 cells. Furthermore, Notch3 activation renders OVCA429 cells more resistant to carboplatin-induced cytotoxicity and attenuates carboplatin-induced apoptosis in these cells. Our results indicate that phosphorylation of ERK is a positive regulator of carboplatin-induced apoptosis in OVCA429 cells. Interestingly, carboplatin-induced ERK phosphorylation is inhibited by Notch3 activation.

CONCLUSIONS

Notch3 activation induces EMT and attenuates carboplatin-induced apoptosis in OVCA429 cells. ERK phosphorylation plays a pro-apoptotic role in carboplatin-induced apoptosis in OVCA429 cells. Interestingly, Notch3 activation attenuates carboplatin-induced ERK phosphorylation in these cells.

In vivo and in vitro properties of ovarian cancer cells

Specific biological properties of ovarian cancer cells can be modeled and studied using in vitro experiments. Any experimental setting can closely reflect some aspects of the native conditions; however, parameters that differ from in vivo aspects must be considered. Familiarity with existing and well-established, as well as new, cell culture techniques provides a basis for correct experimental design and production of reliable scientific results. This chapter presents a short comparative review of the techniques used for cell culture establishment and maintenance of ovarian cancer cells, as well as laboratory methods used to characterize malignant features of these cells, including the epithelial-mesechymal transition, cell motility and invasiveness, resistance to detachment-induced apoptosis, and stem cell content.

FOXM1 (Forkhead box M1) in tumorigenesis: overexpression in human cancer, implication in tumorigenesis, oncogenic functions, tumor-suppressive properties, and target of anticancer therapy

FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor and is also intimately involved in tumorigenesis. FOXM1 stimulates cell proliferation and cell cycle progression by promoting the entry into S-phase and M-phase. Additionally, FOXM1 is required for proper execution of mitosis. In accordance with its role in stimulation of cell proliferation, FOXM1 exhibits a proliferation-specific expression pattern and its expression is regulated by proliferation and anti-proliferation signals as well as by proto-oncoproteins and tumor suppressors. Since these factors are often mutated, overexpressed, or lost in human cancer, the normal control of the foxm1 expression by them provides the basis for deregulated FOXM1 expression in tumors. Accordingly, FOXM1 is overexpressed in many types of human cancer. FOXM1 is intimately involved in tumorigenesis, because it contributes to oncogenic transformation and participates in tumor initiation, growth, and progression, including positive effects on angiogenesis, migration, invasion, epithelial-mesenchymal transition, metastasis, recruitment of tumor-associated macrophages, tumor-associated lung inflammation, self-renewal capacity of cancer cells, prevention of premature cellular senescence, and chemotherapeutic drug resistance. However, in the context of urethane-induced lung tumorigenesis, FOXM1 has an unexpected tumor suppressor role in endothelial cells because it limits pulmonary inflammation and canonical Wnt signaling in epithelial lung cells, thereby restricting carcinogenesis. Accordingly, FOXM1 plays a role in homologous recombination repair of DNA double-strand breaks and maintenance of genomic stability, that is, prevention of polyploidy and aneuploidy. The implication of FOXM1 in tumorigenesis makes it an attractive target for anticancer therapy, and several antitumor drugs have been reported to decrease FOXM1 expression.

Migfilin, α-parvin and β-parvin are differentially expressed in ovarian serous carcinoma effusions, primary tumors and solid metastases

OBJECTIVE

The objective of this study is to analyze the expression and clinical role of integrin-linked kinase (ILK), α-parvin, β-parvin and migfilin in advanced-stage serous ovarian carcinoma.

METHODS

Expression of these 4 proteins was investigated in 205 effusions and in 94 patient-matched solid lesions (33 primary tumors and 61 solid metastases) using immunohistochemistry. Protein expression was analyzed for association with clinicopathologic parameters and survival.

RESULTS

ILK, α-parvin, β-parvin and migfilin were expressed in tumor cells in 53%, 2%, 28% and 53% of effusions and 57%, 20%, 83% and 25% of solid lesions, respectively. Statistical analysis showed significantly higher α-parvin and β-parvin expression in primary carcinomas (p=0.02 and p=0.001, respectively) and solid metastases (p=0.001 and p<0.001, respectively), compared to effusions, with opposite findings for migfilin (p=0.006 and p=0.008 for primary carcinomas and solid metastases, respectively). ILK expression was comparable at all anatomic sites. β-Parvin expression in effusions was associated with better response to chemotherapy at diagnosis (p=0.014), with no other significant association with clinicopathologic parameters or survival. Expression in primary tumors and solid metastases was similarly unrelated to clinicopathologic parameters or survival.

CONCLUSIONS

This study provides further evidence to our previous observations that the adhesion profile of ovarian serous carcinoma cells in effusions differs from their counterparts in primary carcinomas and solid metastases. β-Parvin may be a novel marker of chemoresponse in metastatic ovarian carcinoma.