Targeted therapy for epithelial ovarian cancer: Current status and future prospects

You are what you eat: Sequence analysis reveals how plant microRNAs may regulate the human genome

BACKGROUND

Nutrigenomic has revolutionized our understanding of nutrition. As plants make up a noticeable part of our diet, in the present study we chose microRNAs of edible plants and investigated if they can perfectly match human genes, indicating potential regulatory functionalities.

METHODS

miRNAs were obtained using the PNRD database. Edible plants were separated and microRNAs in common in at least four of them entered our analysis. Using vmatchPattern, these 64 miRNAs went through four steps of refinement to improve target prediction: Alignment with the whole genome (2581 results), filtered for those in gene regions (1371 results), filtered for exon regions (66 results) and finally alignment with the human CDS (41 results). The identified genes were further analyzed in-silico to find their functions and relations to human diseases.

RESULTS

Four common plant miRNAs were identified to match perfectly with 22 human transcripts. The identified target genes were involved in a broad range of body functions, from muscle contraction to tumor suppression. We could also indicate some connections between these findings and folk herbology and botanical medicine.

CONCLUSIONS

The food that we regularly eat has a great potential in affecting our genome and altering body functions. Plant miRNAs can provide means of designing drugs for a vast range of health problems including obesity and cancer, since they target genes involved in cell cycle (CCNC), digestion (GIPR) and muscular contractions (MYLK). They can also target regions of CDS for which we still have no sufficient information, to help boost our knowledge of the human genome.

Cyclin-Dependent Kinase 11 (CDK11) Is Required for Ovarian Cancer Cell Growth In Vitro and In Vivo, and Its Inhibition Causes Apoptosis and Sensitizes Cells to Paclitaxel

Ovarian cancer is currently the most lethal gynecologic malignancy with limited treatment options. Improved targeted therapies are needed to combat ovarian cancer. Here, we report the identification of cyclin-dependent kinase 11 (CDK11) as a mediator of tumor cell growth and proliferation in ovarian cancer cells. Although CDK11 has not been implicated previously in this disease, we have found that its expression is upregulated in human ovarian cancer tissues and associated with malignant progression. Metastatic and recurrent tumors have significantly higher CDK11 expression when compared with the matched, original primary tumors. RNAi-mediated CDK11 silencing by synthetic siRNA or lentiviral shRNA decreased cell proliferation and induced apoptosis in ovarian cancer cells. Moreover, CDK11 knockdown enhances the cytotoxic effect of paclitaxel to inhibit cell growth in ovarian cancer cells. Systemic in vivo administration of CDK11 siRNA reduced the tumor growth in an ovarian cancer xenograft model. Our findings suggest that CDK11 may be a promising therapeutic target for the treatment of ovarian cancer patients. Mol Cancer Ther; 15(7); 1691-701. ©2016 AACR.

Hybrid-polymerase chain reaction to identify novel target genes of miR-134 in paclitaxel resistant human ovarian carcinoma cells

Increasing evidence has shown that miR-134 is involved in the promotion of tumorigenesis and chemoresistance. However, whether miR-134 participates in ovarian cancer chemoresistance and its functional targets still remains unclear. The objective of this study was to apply hybrid-polymerase chain reaction (PCR) to screen target genes of miR-134 in ovarian carcinoma paclitaxel resistant SKOV3-TR30 cells, and to provide a number of novel targets of miR-134 for further study of ovarian cancer paclitaxel resistance. The current study found that miR-134 was decreased in SKOV3-TR30 cells compared with the parental SKOV3 cell line. By applying hybrid-PCR, 8 putative target genes of miR-134 in SKOV3-TR30 cells were identified, including C16orf72, PNAS-105, SRM, VIM, F-box protein 2, GAPDH, PRPF6 and RPL41. Notably, the target sites of VIM and PRPF6 were not located in 3'untranslated region, but rather in the coding sequence region. By conducting a luciferase reporter assay, miR-134 was demonstrated to recognize the putative binding sites of these target genes including VIM and PRPF6. Transfecting SKOV3-TR30 cells with miR-134 mimic and performing reverse transcription-PCR in addition to western blot analysis confirmed that miR-134 regulates vimentin expression at a post transcriptional level. This finding provides a novel perspective for studying the mechanism of miR-134/mRNA interaction. In conclusion, this study was the first to apply an effective method of hybrid-PCR to screen putative target mRNAs of miR-134 in paclitaxel resistant SKOV3-TR30 cells and indicate that miR-134 may contribute to the induction of SKOV3-TR30 paclitaxel resistance by targeting these genes.

Prognostic biomarkers in ovarian cancer

Epithelial ovarian cancer (EOC) remains the most lethal gynecological malignancy despite several decades of progress in diagnosis and treatment. Taking advantage of the robust development of discovery and utility of prognostic biomarkers, clinicians and researchers are developing personalized and targeted treatment strategies. This review encompasses recently discovered biomarkers of ovarian cancer, the utility of published prognostic biomarkers for EOC (especially biomarkers related to angiogenesis and key signaling pathways), and their integration into clinical practice.

AGR2, a mucinous ovarian cancer marker, promotes cell proliferation and migration

Ovarian cancer is a leading cause of death in women. Early detection of ovarian cancer is essential to decrease mortality. However, the early diagnosis of ovarian cancer is difficult due to a lack of clinical symptoms and suitable molecular diagnostic markers. Thus, identification of meaningful tumor biomarkers with potential clinical application is clearly needed. To search for a biomarker for the early detection of ovarian cancer, we identified human anterior gradient 2 (AGR2) from our systematic analysis of paired normal and ovarian tumor tissue cDNA microarray. We noted a marked overexpression of AGR2 mRNA and protein in early stage mucinous ovarian tumors compared to normal ovarian tissues and serous type ovarian tumors by Western blot analysis and immunohistochemistry. To further elucidate the role of AGR2 in ovarian tumorigenesis, stable 2774 human ovarian cancer cell lines overexpressing AGR2 were established. Forced expression of AGR2 in 2774 cells enhanced the growth and migration of ovarian cancer cells. AGR2 protein was detected in the serum of mucinous ovarian cancer patients by Western blot and ELISA analysis. Thus, AGR2 is a potential biomarker for the diagnosis of mucinous ovarian cancer and an ELISA assay may facilitate the early detection of mucinous ovarian cancer using patient serum.

Epidermal growth factor receptor-mediated membrane type 1 matrix metalloproteinase endocytosis regulates the transition between invasive versus expansive growth of ovarian carcinoma cells in three-dimensional collagen

The epidermal growth factor receptor (EGFR) is overexpressed in ovarian carcinomas and promotes cellular responses that contribute to ovarian cancer pathobiology. In addition to modulation of mitogenic and motogenic behavior, emerging data identify EGFR activation as a novel mechanism for rapid modification of the cell surface proteome. The transmembrane collagenase membrane type 1 matrix metalloproteinase (MT1-MMP, MMP-14) is a major contributor to pericelluar proteolysis in the ovarian carcinoma microenvironment and is subjected to extensive posttranslational regulation. In the present study, the contribution of EGFR activation to control of MT1-MMP cell surface dynamics was investigated. Unstimulated ovarian cancer cells display caveolar colocalization of EGFR and MT1-MMP, whereas EGFR activation prompts internalization via distinct endocytic pathways. EGF treatment results in phosphorylation of the MT1-MMP cytoplasmic tail, and cells expressing a tyrosine mutated form of MT1-MMP (MT1-MMP-Y(573)F) exhibit defective MT1-MMP internalization. As a result of sustained cell surface MT1-MMP activity, a phenotypic epithelial-mesenchymal transition is observed, characterized by enhanced migration and collagen invasion, whereas growth within three-dimensional collagen gels is inhibited. These data support an EGFR-dependent mechanism for regulation of the transition between invasive and expansive growth of ovarian carcinoma cells via modulation of MT1-MMP cell surface dynamics.

The biology of ovarian cancer: new opportunities for translation

Over the past two decades, the 5-year survival for ovarian cancer patients has substantially improved owing to more effective surgery and treatment with empirically optimized combinations of cytotoxic drugs, but the overall cure rate remains approximately 30%. Many investigators think that further empirical trials using combinations of conventional agents are likely to produce only modest incremental improvements in outcome. Given the heterogeneity of this disease, increases in long-term survival might be achieved by translating recent insights at the molecular and cellular levels to personalize individual strategies for treatment and to optimize early detection.

Diverse cross-resistance phenotype to ET-743 and PM00104 in multi-drug resistant cell lines

PURPOSE

ET-743 (Yondelis, trabectedin) and PM00104 (Zalypsis) are marine derived compounds which demonstrate anti-tumor activity. The present study was performed to elucidate the relationship between the expression of ABCB1/MDR1 and ABCC1/MRP1 with resistance to either ET-743 or PM00104.

METHODS

We evaluate the association between expression of Pgp1, MRP1, and BCRP proteins and ET-743 or PM00104 resistance in a large panel of multi-drug resistant cell lines derived from histologically unrelated human tumors that were selected with paclitaxel, doxorubicin, cisplatin, mitoxantrane, or gemcitibine.

RESULTS

Paclitaxel selected resistant cell lines expressed high levels of ABCB1 (but not ABCC1 or ABCG2/BCRP) did not demonstrate cross-resistance to either ET-743 or PM00104. In contrast, the doxorubicin selected resistant cell lines also expressed high level of ABCB1 (but not ABCC1 or ABCG2) but did demonstrate significant cross-resistance to both ET-743 and PM00104. The paclitaxel selected cell lines demonstrated cross-resistance to doxorubicin, vincristine, and mitoxantrane, while most of the above doxorubicin selected cell lines demonstrated cross-resistance to paclitaxel and vincristine, but not to mitoxantrane. On the contrary, cisplatin and gemcitabine selected cell lines demonstrated no cross-resistance to paclitaxel, doxorubicin, ET-743, or PM00104. siRNA down-regulation of ABCB1 expression in doxorubicin selected cell lines caused partial sensitization to both doxorubicin and paclitaxel but not to either ET-743 or PM00104.

CONCLUSIONS

These results indicate that cell lines selected for resistance to either paclitaxel or doxorubicin are cross-resistant to many other drugs and that, for these cell lines, ABCB1 over-expression is not necessary to confer resistance to either ET-743 or PM00104. Diversity of cross-resistance observed in these multi-drug resistant cell lines are associated with the initial drug used for in vitro selection, but not to ABCB1 expression. This study suggests that a common molecular pathway other than ABCB1 may be involved in the mechanism of resistance to ET-743 or PM00104.

Lysophosphatidic acid receptors determine tumorigenicity and aggressiveness of ovarian cancer cells

BACKGROUND

Lysophosphatidic acid (LPA) acts through the cell surface G protein-coupled receptors, LPA1, LPA2, or LPA3, to elicit a wide range of cellular responses. It is present at high levels in intraperitoneal effusions of human ovarian cancer increasing cell survival, proliferation, and motility as well as stimulating production of neovascularizing factors. LPA2 and LPA3 and enzymes regulating the production and degradation of LPA are aberrantly expressed by ovarian cancer cells, but the consequences of these expression changes in ovarian cancer cells were unknown.

METHODS

Expression of LPA1, LPA2, or LPA3 was inhibited or increased in ovarian cancer cells using small interfering RNAs (siRNAs) and lentivirus constructs, respectively. We measured the effects of changes in LPA receptor expression on cell proliferation (by crystal violet staining), cell motility and invasion (using Boyden chambers), and cytokines (interleukin 6 [IL-6], interleukin 8 [IL-8], and vascular endothelial growth factor [VEGF]) production by enzyme-linked immunosorbent assay. The role of LPA receptors in tumor growth, ascites formation, and cytokine production was assessed in a mouse xenograft model. All statistical tests were two-sided.

RESULTS

SKOV-3 cells with increased expression of LPA receptors showed increased invasiveness, whereas siRNA knockdown inhibited both migration (P < .001, Student t test) and invasion. Knockdown of the LPA2 or LPA3 receptors inhibited the production of IL-6, IL-8, and VEGF in SKOV-3 and OVCAR-3 cells. SKOV-3 xenografts expressing LPA receptors formed primary tumors of increased size and increased ascites volume. Invasive tumors in the peritoneal cavity occurred in 75% (n = 4) of mice injected with LPA1 expressing SKOV-3 and 80% (n = 5) of mice injected with LPA2 or LPA3 expressing SKOV-3 cells. Metastatic tumors expressing LPA1, LPA2, and LPA3 were identified in the liver, kidney, and pancreas; tumors expressing LPA2 and LPA3 were detected in skeletal muscle; and tumors expressing LPA2 were also found in the cervical lymph node and heart. The percent survival of mice with tumors expressing LPA2 or LPA3 was reduced in comparison with animals with tumors expressing beta-galactosidase.

CONCLUSIONS

Expression of LPA2 or LPA3 during ovarian carcinogenesis contributes to ovarian cancer aggressiveness, suggesting that the targeting of LPA production and action may have potential for the treatment of ovarian cancer.

Lentiviral short hairpin RNA screen of genes associated with multidrug resistance identifies PRP-4 as a new regulator of chemoresistance in human ovarian cancer

Published reports implicate a variety of mechanisms that may contribute to drug resistance in ovarian cancer. The chief aim of this study is to understand the relationship between overexpression of drug resistance associated genes and multidrug resistance in ovarian cancer. Using lentiviral short hairpin RNA collections targeting 132 genes identified from transcriptional profiling of drug-resistant cancer cell lines, individual knockdown experiments were done in the presence of sublethal doses of paclitaxel. Specific genes whose knockdown was found to be associated with cellular toxicity included MDR1 (ABCB1), survivin, and pre-mRNA processing factor-4 (PRP-4). These genes, when repressed, can reverse paclitaxel resistance in the multidrug-resistant cell line SKOV-3(TR) and OVCAR8(TR). Both MDR1 and survivin have been reported previously to play a role in multidrug resistance and chemotherapy-induced apoptosis; however, the effect of PRP-4 expression on drug sensitivity is currently unrecognized. PRP-4 belongs to the serine/threonine protein kinase family, plays a role in pre-mRNA splicing and cell mitosis, and interacts with CLK1. Northern analysis shows that PRP-4 is overexpressed in several paclitaxel-resistant cell lines and confirms that PRP-4 expression could be significantly repressed by PRP-4 lentiviral short hairpin RNA. Both clonogenic and MTT assays confirm that transcriptional repression of PRP-4 could reverse paclitaxel resistance 5-10-fold in SKOV-3(TR). Finally, overexpression of PRP-4 in drug-sensitive cells could induce a modest level of drug resistance to paclitaxel, doxorubicin, and vincristine.

Profiling studies in ovarian cancer: a review

Ovarian cancer is a heterogeneous disease with respect to histopathology, molecular biology, and clinical outcome. In advanced stages, surgery and chemotherapy result in an approximately 25% overall 5-year survival rate, pointing to a strong need to identify subgroups of patients that may benefit from targeted innovative molecular therapy. This review summarizes: (a) microarray research identifying gene-expression profiles in ovarian cancer; (b) the methodological flaws in the available microarray studies; and (c) applications of pathway analysis to define new molecular subgroups. Microarray technology now permits the analysis of expression levels of thousands of genes. So far seven studies have aimed to identify a genetic profile that can predict survival/clinical outcome and/or response to platinum-based therapy. To date, the clinical evidence of prognostic microarray studies has only reached the level of small retrospective studies, and there are other issues that may explain the nonreproducibility among the reported prognostic profiles, such as overfitting, technical platform differences, and accuracy of measurements. We consider pathway analysis a promising new strategy. The accumulation of small differential expressions within a meaningful molecular regulatory network might lead to a critical threshold level, resulting in ovarian cancer. Microarray technologies have already provided valuable expression data for classifying ovarian cancer and the first clues about which molecular changes in ovarian cancer could be exploited in new treatment strategies. Further improvements in technology as well as in study design, combined with pathway analysis, will allow us to detect even more subtle tumor expression differences among subgroups of ovarian cancer patients. Disclosure of potential conflicts of interest is found at the end of this article.

A phase II and pharmacodynamic study of gefitinib in patients with refractory or recurrent epithelial ovarian cancer

BACKGROUND

The primary objective of this study was to evaluate the biochemical effects of gefitinib on its target signal-transduction pathways in patients with recurrent epithelial ovarian cancer (EOC). The secondary objectives included assessing clinical activity and toxicity and determining the association between biochemical and clinical outcomes.

METHODS

Twenty-four heavily pretreated patients with EOC who had good end-organ function and performance status and who had measurable disease received gefitinib 500 mg daily. Prospectively planned core-needle tumor biopsies were obtained before treatment and after 4 weeks. Protein expression of total and phosphorylated (p) epidermal growth factor receptor (EGFR), protein kinase B (AKT), and extracellular regulated kinase (ERK) was quantified in microdissected tumor cells using tissue lysate array proteomics.

RESULTS

All tumor samples had detectable levels of EGFR and p-EGFR. A decrease in the quantity of both EGFR and p-EGFR was observed with gefitinib therapy in >50% of patients. This was not associated with clinical benefit, nor were responses observed. However, trends for increased gastrointestinal and skin toxicity were observed with greater phosphorylation or quantities of EGFR, ERK, and AKT in tumor samples (P </= .05). Gefitinib had limited clinical activity as monotherapy despite documented target inhibition.

CONCLUSIONS

The results from this study demonstrated that gefitinib inhibited the phosphorylation of EGFR in EOC tumor cells, providing proof of target in a clinical setting. Combinatorial therapy with molecular therapeutics against complementary targets may prove successful.

Anticancer and chemosensitizing effects of 2,3-DCPE in ovarian carcinoma cell lines: link with ERK activation and modulation of p21WAF1/CIP1, Bcl-2 and Bcl-xL expression

OBJECTIVE

Emergence of chemoresistance in the course of treatments with platinum drugs remains a major hurdle to ovarian carcinoma therapy. We have previously shown that acquisition of cisplatin resistance by OAW42-R ovarian carcinoma cells was associated with the loss of ERK activation in response to cisplatin. To try to sensitize this cell line by restoring ERK activation, we tested a new synthetic compound, 2[[3-(2,3-dichlorophenoxy)propyl]amino]ethanol (2,3-DCPE), which was described to induce ERK activation and to display anticancer properties.

METHODS

We treated four ovarian carcinoma cell lines with 2,3-DCPE, alone or combined with cisplatin. We characterized its effects on apoptosis induction and proliferation and correlated them with molecular modulations.

RESULTS

We showed that 2,3-DCPE induced cell death and ERK phosphorylation in a time- and concentration-dependent manner in OAW42-R cells. 2,3-DCPE-triggered apoptosis was also associated with the inhibition of Bcl-2 expression and, to a less extent, with that of Bcl-xL. Treatment with 2,3-DCPE also elicited a strong G0/G1 cell cycle arrest, accompanied with p21WAF1/CIP1 up-regulation. All of these effects revealed to be irreversible. Moreover, 2,3-DCPE exerted a cytostatic effect on OAW42, IGROV1-R10 and SKOV3 ovarian carcinoma cells, the sensitivity to 2,3-DCPE appearing in particular linked with a low basal level of P-ERK. Finally, we showed that 2,3-DCPE increased the cytotoxic effect of cisplatin in OAW42-R resistant cells.

CONCLUSION

Our results emphasized the potential interest of 2,3-DCPE, used alone or combined with cisplatin, for ovarian carcinoma treatment. The absence of basal P-ERK may constitute a predictive marker of response to this novel therapy.

Molecular targets in gynaecological cancers

The application of high throughput expression profiling and other advanced molecular biology laboratory techniques has revolutionised the management of cancers and is gaining attention in the field of gynaecological cancers. Such new approaches may help to improve our understanding of carcinogenesis and facilitate screening and early detection of gynaecological cancers and their precursors. Individualised prediction of patients' responses to therapy and design of personalised molecular targeted therapy is also possible. The studies of various molecular targets involved in the various signal pathways related to carcinogenesis are particularly relevant to such applications. At the moment, the application of detection and genotyping of human papillomavirus in management of cervical cancer is one of the most well established appliances of molecular targets in gynaecological cancers. Methylation, telomerase and clonality studies are also potentially useful, especially in assisting diagnosis of difficult clinical scenarios. This post-genomic era of clinical medicine will continue to make a significant impact in routine pathology practice. The contribution of pathologists is indispensable in analysis involving tissue microarray. On the other hand, both pathologists and bedside clinicians should be aware of the limitation of these molecular targets. Interpretation must be integrated with clinical and histopathological context to avoid misleading judgement. The importance of quality assurance of all such molecular techniques and their ethical implications cannot be over-emphasised.

Prostate-derived Ets Factor Is Overexpressed in Serous Epithelial Ovarian Tumors

The frequent overexpression of prostate-derived Ets factor (PDEF) mRNA in ovarian cancer has been previously reported. The aim of this study was to evaluate PDEF protein expression in ovarian cancer and how this expression might vary at different stages of epithelial ovarian tumors in comparison to normal ovary. A new rabbit polyclonal antibody to PDEF was prepared, and immunohistochemistry was performed on tissue sections from 12 normal ovaries, 10 cases of benign serous cystadenoma, 17 cases of low malignant potential tumor, 19 cases of stage 1, and 15 cases of advanced stage primary epithelial (serous) ovarian carcinomas and their peritoneal metastases. Expression levels were assessed based on the percentage of positively staining cells and the intensity of staining. All 12 normal ovary and 10 benign serous cystadenoma cases were negative for PDEF expression. In contrast, 6 of 17 (35%) low malignant potential tumors, 5 of 19 (27%) stage 1, and 5 of 15 (33%) advanced stage ovarian tumors stained positive for PDEF expression. Together, these results show frequent overexpression of PDEF protein in epithelial ovarian tumors and its lack of expression in normal ovary and cystadenomas, and this supports a role for PDEF in ovarian tumorigenesis. Furthermore, these results suggest that PDEF is a potential marker and target in ovarian cancer.

Prognostic significance of vascular endothelial growth factor expression in ovarian cancer patients: a long-term follow-up

The purpose of the study was to determine vascular endothelial growth factor (VEGF) concentrations in ascites from ovarian cancer and to correlate these data with VEGF expression in ovarian tumors, serum VEGF concentrations, and clinicopathologic characteristics. Ascites, serum, and tumor tissue from 65 ovarian carcinomas and eight borderline tumors were collected. VEGF concentration in peritoneal fluids and sera was determined using enzyme immunoassay. VEGF tumor expression was evaluated immunohistochemically. Significantly higher VEGF concentrations were found in ascites from malignant tumors (median, 2575 pg mL(-1)) compared with borderline tumors (median 181.9 pg mL(-1)) and benign peritoneal fluid (184.5 pg mL(-1)). Both VEGF ascites concentration and tumor expression correlated with advanced tumor stages and ascites volume. Elevated VEGF ascites levels were negatively correlated to patient survival. No differences between VEGF serum levels could be observed between ovarian cancer patients and patients with benign cysts. This study showed for the first time the clinical significance of elevated VEGF ascites level in ovarian carcinomas. VEGF is expressed by ovarian tumor cells and locally released in the malignant peritoneal fluid but is not increased in the serum of preoperative ovarian cancer patients. The enhanced VEGF level support novel therapeutic perspectives by VEGF inhibition.

Clinicopathologic study of vascular endothelial growth factor, thrombospondin-1, and microvessel density assessed by CD34 in patients with stage III ovarian carcinoma

The aim of the study was to investigate angiogenesis in patients with advanced-stage ovarian carcinoma. We used paraffin-embedded tumor tissues from 33 patients diagnosed with FIGO III ovarian cancer who had optimal surgery and received platinum-based chemotherapy. The tissue expression of CD34, vascular endothelial growth factor (VEGF), and thrombospondin-1 (TSP-1) was assessed immunohistochemically. CD34 stained hot spot areas were used to evaluate tumor microvessel density (MVD). VEGF and TSP-1 were assessed by semiquantitative methods. The studied molecules were investigated for relationship with standard clinicopathologic parameters. MVD count was high: median value of 39, range 12-143 microvessels/mm2. VEGF was present in all cases and stained strong in 91%. Stroma staining for TSP-1 was weak in 79% of the cases, strong in 6%, and absent in five (15%). We did not find correlations between the three studied markers and histologic type or tumor grade. MVD score did not relate to VEGF or TSP-1. We only observed a trend toward a longer survival in patients with tumors expressing high TSP-1 (60 vs. 36 months, P= 0.1). Proangiogenetic factor VEGF is highly expressed in advanced-stage ovarian carcinomas. The findings of this study may offer support for considering VEGF-targeted therapeutics in ovarian cancer treatment research.

Antisense suppression of pygopus2 results in growth arrest of epithelial ovarian cancer

PURPOSE

The Pygopus proteins are critical elements of the canonical Wnt/beta-catenin transcriptional complex. In epithelial ovarian cancer, constitutively active Wnt signaling is restricted to one (endometrioid) tumor subtype. The purpose of this study was to determine the level of expression and growth requirements of human Pygopus2 (hPygo2) protein in epithelial ovarian cancer.

EXPERIMENTAL DESIGN

Expression and subcellular localization of hPygo2 was determined in epithelial ovarian cancer cell lines and tumors using Northern blot, immunoblot, and immunofluorescence. Immunohistochemistry was done on 125 archived patient epithelial ovarian cancer tumors representing all epithelial ovarian cancer subtypes. T-cell factor-dependent transcription levels were determined in epithelial ovarian cancer cells using TOPflash/FOPflash in vivo assays. Phosphorothioated antisense oligonucleotides were transfected into cell lines and growth assayed by cell counting, anchorage-independent colony formation on soft agar, and xenografting into severe combined immunodeficient mice.

RESULTS

All six epithelial ovarian cancer cell lines and 82% of the patient samples overexpressed nuclear hPygo2 compared with control cells and benign disease. Depletion of hPygo2 by antisense oligonucleotides in both Wnt-active (TOV-112D) and Wnt-inactive serous (OVCAR-3, SKOV-3) and clear cell (TOV-21G) carcinoma cell lines halted growth, assessed using tissue culture, anchorage-independent, and xenograft assays.

CONCLUSIONS

hPygo2 is unexpectedly widely expressed in, and required in the absence of, Wnt signaling for malignant growth of epithelial ovarian cancer, the deadliest gynecologic malignancy. These findings strongly suggest that inhibition of hPygo2 may be of therapeutic benefit for treating this disease.

Enhanced efficiency and specificity of ovarian cancer gene therapy in rats with a novel nonviral gene delivery system (GE7) via intraovarian artery perfusion approach

Transfer of the herpes simplex virus type I-thymidine kinase gene, followed by the administration of ganciclovir (HSV1-tk/GCV) into ovarian cancer-derived cell line either in vitro or transplanted into nude mice has been shown to provide a potential strategy for the gene therapy of ovarian cancer. We investigated the antitumor effects of HSV1-tk/GCV strategy with a chemically induced rat ovarian cancer model and a tumor-selective gene delivery by a novel nonviral gene delivery system (GE7) through the ovarian artery and tail vein. We demonstrated the expression of a reporter gene, beta-gal gene, as well as HSV1-tk gene in tumors and other organs, evaluated the overall antitumor effects after the GCV treatment and analyzed the tumor cell cycle phase distribution. Via the ovarian artery route, the expressions of beta-gal and HSV1-tk in tumors were significantly stronger than those expressed in such organs as the hearts, livers, spleens, lungs and kidneys. However, no beta-gal and HSV1-tk were detected in the tumor tissues when administrated via the tail vein, and little was found in other organs. The cell cycle analysis showed that the total S-phase of tumor cells in the test intra-arterial treatment group was considerably higher than that of the controls. The weight of the tumor tissues in the group treated by the intra-arterial route (4.06+/-2.12 g) was much less than the group treated intravenously (18.25+/-8.34 g) (P<.01). These findings indicated that the administration of GE7/HSV1-tk complex via the ovarian artery route could be a promising avenue of future human ovarian cancer treatment.

Prognostic, predictive and therapeutic implications of HER2 in invasive epithelial ovarian cancer

The HER2 oncogene encodes a transmembrane protein partially homologous to epidermal growth factor receptor. This oncogene has been studied mainly in breast cancer where it has prognostic, predictive and therapeutic target value. The expression of HER2 in epithelial ovarian cancer has been less studied. HER2 expression can be determined through IHC, FISH, CISH and ELISA among other tests, with reported positivity frequencies of overexpression varying from 1.8% to 76%. In some studies HER2 overexpression has been associated with advanced stages, poorly differentiated tumors, resistance to chemotherapy and shortened survival. Although trastuzumab is able to produce a low response rate as a single agent in pretreated ovarian cancer patients with overexpression of HER2, its usefulness is limited due to the low frequency of strong expression. To date there is not enough bases for assessment and HER2-based therapies in epithelial ovarian cancer.

The biological differences between ovarian serous carcinoma and diffuse peritoneal malignant mesothelioma

Recent improvements in immunohistochemistry panels used for differentiating ovarian serous carcinoma/primary peritoneal carcinoma (OC/PPC) from diffuse malignant peritoneal mesothelioma (DMPM) have resulted in improved diagnostic rates for these tumors in both cytological and histological material. However, little is known about the biological characteristics that differentiate these two cancer types. We performed a comparative analysis of cancer-associated molecule expression data for a cohort consisting of up to 270 serous OC/PPC specimens (only peritoneal lesions) and 32 peritoneal MM. The molecules studied were nerve growth factor receptors (p75, p-TrkA), angiogenic factors (VEGF, IL-8, bFGF, heparanase), laminin receptors (the 67-kDa receptor and the alpha 6 integrin subunit), proteases (MMP-2), immune response mediators (HLA-G), and signaling molecules (the MAPK members ERK, JNK, and p38). The methods used were immunohistochemistry, Western blotting, and RT-PCR. DMPM specimens showed significantly higher expression of p75 (P < 0.001), p-TrkA (P < 0.001), and bFGF (P < 0.001), and significantly lower expression of the 67-kDa receptor (P < 0.001), alpha 6 integrin subunit (P = 0.025), VEGF (P < 0.001), IL-8 (P < 0.001), and HLA-G (P = 0.039) compared with OC/PPC. DMPM specimens showed higher activation ratio (phosphorylated/total enzyme ratio) of all three MAPK members (ERK, P = 0.017; JNK, P < 0.001; p38, P = 0.009) compared with OC/PPC. These data document significant differences in the expression of cancer- and metastasis-associated molecules in MM compared with ovarian carcinoma, and suggest that different biological pathways are involved in tumorigenesis and disease progression in these two tumors.

Inhibition of phosphatidylinositol 3-kinase sensitizes ovarian cancer cells to carboplatin and allows adjunct chemotherapy treatment

Signal transduction pathways associated with cancer progression and chemotherapeutic resistance are being investigated as molecular targets for chemotherapy. The phosphatidylinositol 3-kinase (PI3K) pathway has been found to be frequently amplified and have increased activity in ovarian cancer. The current study investigates the efficacy of an antagonist of PI3K, LY294002, in inhibiting ovarian cancer cell growth and survival both in vitro and in vivo. The hypothesis tested is that inhibition of PI3K signaling makes ovarian cancer cells susceptible to the effects of platinum-based chemotherapy. Observations show that LY294002 is an effective inhibitor of ovarian cancer cell growth and survival in vitro. Inhibition of PI3K/Akt signaling increased the sensitivity of ovarian cell cultures to the cytotoxic effects of carboplatin. The combined treatment of LY294002 and carboplatin was needed to optimally promote cellular apoptosis and decrease ovarian cancer cell survival in vitro. To extend these observations, a model involving in vivo i.p. growth of human ovarian tumors in a nude mouse was used. LY294002 in combination with carboplatin was more effective in inhibiting ovarian cancer cell xenograft growth than either agent alone. The results of this study suggest that the combined treatment of carboplatin and LY294002 can effectively decrease ovarian tumor progression and support the use of a PI3K inhibitor (e.g., LY294002) as an adjunct platinum-based drug therapy for treatment of ovarian cancer.

Cancer-associated serum antigen level: a novel prognostic indicator for survival in patients with recurrent ovarian carcinoma

The aim was to examine the value of the pretherapeutic serum cancer-associated serum antigen (CASA) level as a prognostic factor for survival in patients with recurrent epithelial ovarian carcinoma. Serum levels of CASA and cancer antigen (CA)125 were prospectively determined in 70 consecutive patients with recurrent ovarian cancer before the start of second-line chemotherapy. Univariate and multivariate analyses of survival were performed. The median level of serum CASA was 6.5 U/mL (range: 0.2-1437 U/mL). Univariate analysis showed that patients with a CASA level >10.0 U/mL had significantly shorter survival than patients with CASA level < or =10.0 U/mL (P= 0.002). Using different CASA cutoff levels (6.0, 6.5, and 10.0 U/mL), multivariate Cox analyses identified CASA as an independent prognostic factor for survival at every cutoff level. The strongest prognostic function for CASA was found at a cutoff level of 10.0 U/mL (>10 vs < or =10 U/mL; hazard ratio, 2.7; 95% confidence interval, 1.6-4.7; P < 0.001). The pretreatment CA125 level was not found to be significantly associated with survival by any of the cutoffs (35, 65, 132, and 339 U/mL). A pretreatment elevated level of the tumor marker CASA is an adverse prognostic factor for survival in patients with ovarian cancer relapse.

18F-FDG PET/CT in the evaluation of recurrent ovarian cancer: a prospective study on forty-one patients

AIM

Many patients with ovarian cancer are at high risk of recurrence especially in the 2 years following first-line therapy. CA125 serum levels measurement associated to computed tomography (CT), ultrasound (US) and magnetic resonance imaging (MRI) are currently used during follow-up to detect recurrent disease. Unfortunately, in a relevant percentage of cases all of these traditional imaging techniques provide a significant number of doubtful/equivocal results or turn out negative even in presence of elevated Ca125 levels. Aim of our study was to evaluate sensitivity, specificity and accuracy of (18)F-FDG PET/CT in a group of patients with suspicion of ovarian cancer recurrence.

METHODS

We prospectively evaluated 41 patients with a mean age of 59.4 years who had been previously treated for ovarian cancer with surgery and radio-chemotherapy or radio-chemotherapy alone. Following the performance of traditional radiologic imaging (US, CT, MRI) and Ca125 measurement, all patients underwent additional (18)F-FDG PET/CT. PET/CT results were compared with histologic findings or clinical, laboratory and repeated traditional imaging techniques during subsequent follow-up data.

RESULTS

Of 41 patients 32 had a positive PET-CT (30 true positive, two false positive) whereas nine a negative PET/CT (five true negative, four false negative). Overall, in our experience (18)F-FDG PET/CT provided a good sensitivity (88.2%), specificity (71.4%) and accuracy (85.4%), superior to that reported in literature for traditional radiologic imaging.

CONCLUSIONS

It can be concluded that (18)F-FDG PET/CT appears to be a useful and accurate tool in disclosing early recurrent ovarian cancer.

Expression of xeroderma pigmentosum A protein predicts improved outcome in metastatic ovarian carcinoma

BACKGROUND

The nucleotide excision repair (NER) proteins repair DNA adducts due to xenobiotics and cancer chemotherapy. The authors hypothesized that expression of the NER protein xeroderma pigmentosum A (XPA) would be reduced in a clinically significant fashion in metastatic ovarian carcinoma.

METHODS

Malignant effusion specimens were studied so that there was a uniform metastatic ovarian carcinoma population for study. XPA protein expression was analyzed by immunocytochemistry in 142 effusion specimens (109 peritoneal specimens, 33 pleural specimens) from 125 patients. Specimens were obtained at diagnosis (n = 76), and at disease recurrence (n = 66). Patients in the latter group received platinum-based chemotherapy.

RESULTS

XPA was expressed in cancer cells in 136 of the 142 (96%) effusion specimens. Strongest expression occurred in leukocytes and reactive mesothelial cells. XPA expression did not correlate with treatment status, effusion site, International Federation of Gynecology and Obstetrics stage, histologic grade, or the extent of residual disease. More effusion tumor cells from patients with a complete response to chemotherapy expressed XPA compared with those with a partial or no response (P = 0.03, chi(2) test). Patients with recurrent disease with XPA expressed in > 25% of tumor cells had better progression-free survival (PFS) by univariate analysis (median = 0 vs. 11 months, P < 0.001; 95% confidence interval [CI], 1-5, 8-14) and overall survival (OS; median = 24 vs. 34 months, P = 0.04; 95% CI, 17-31, 24-44). XPA was the only predictor of PFS outcome by multivariate analysis (P = 0.03).

CONCLUSIONS

The results of the current study showed that XPA was widely expressed in metastatic ovarian carcinoma effusion specimens and in the cells of the effusion microenvironment. Paradoxically, XPA expression was associated with better response to chemotherapy and predicted better PFS and OS.

Neoadjuvant chemotherapy for epithelial ovarian cancer—role of apoptosis

BACKGROUND

Ovarian cancer is one of the most frequently fatal gynecological cancers because most cases are diagnosed at an advanced stage. Loss of growth control and a marked resistance to apoptosis are considered major mechanisms driving tumor progression. Little is known about the effect of various treatment regimens on the distribution of molecular markers of apoptosis in epithelial ovarian cancer. The objective of this study was to compare the expression levels of both proapoptotic and antiapoptotic proteins p53, p73, Bcl-2, Bcl-XL and survivin in the ascitic cells and tumor samples of patients undergoing treatment with two different regimens.

METHODS

A total of 24 patients with untreated epithelial ovarian cancer were randomized into two groups of 12 each. Group 1 patients received three cycles of chemotherapy prior to surgery and three cycles after surgery and group 2 patients received six cycles of chemotherapy prior to surgery. The expression of apoptosis-related proteins was analyzed in ascitic fluid and tumor samples by Western blotting and immunohistochemistry. The apoptotic index was also determined in these samples by the TUNEL assay.

RESULTS

Significant decreases in antiapoptotic bcl-2 and survivin were seen, accompanied by increases in apoptotic index in tumors that had undergone chemotherapy as compared to the baseline ascites samples. No significant change in bcl-XL was observed. A significant decrease in proapoptotic p53 was also seen. No expression of p73 was observed in tumors or ascites. The findings were similar in groups 1 and 2 patients and were not statistically significantly different, perhaps due to the small sample size (n=12) of each group.

CONCLUSIONS

The above findings indicate that chemotherapy in ovarian carcinoma leads to an increase in apoptosis by a p53-independent pathway, which involves the downregulation of antiapoptotic Bcl-2 and survivin but not Bcl-XL. Furthermore, administering neoadjuvant chemotherapy (six cycles) as an alternative form of therapy for advanced epithelial ovarian cancer is more effective in inducing apoptosis than three cycles. However, the findings of this study need to be corroborated using a larger sample.

Adeno-associated virus-mediated delivery of a mutant endostatin suppresses ovarian carcinoma growth in mice

Earlier studies have shown that a point mutation in human endostatin at position 125 (human endostatin wherein proline 125 was substituted with alanine, P125A-endostatin) improves endothelial cell binding and antiangiogenic activity. In the present study, we investigated the effect of recombinant adeno-associated virus (rAAV)-mediated gene delivery of P125A-endostatin (rAAV-P125Aendo) in a mouse model of ovarian carcinoma. Intramuscular (i.m.) injection of rAAV-P125Aendo resulted in a dose-dependent increase in serum endostatin levels. Consequently, vascular endothelial growth factor- and basic fibroblast growth factor-mediated angiogenesis was significantly inhibited in mice injected with rAAV-P125Aendo as compared to control mice injected with rAAV-LacZ. Furthermore, gene therapy using rAAV-P125Aendo construct showed sustained secretion of P125A-endostatin for up to 9 weeks after a single i.m. administration. Recombinant AAV-P125Aendo injection significantly inhibited the growth of human ovarian cancer cells in athymic nude mice. Immunofluorescence studies of residual tumors surgically removed from the rAAV-P125Aendo-treated animals showed decreased number of vessel ends and vessel length, indicating inhibition of angiogenesis. These studies suggest that recombinant AAV-mediated antiangiogenic gene therapy methods can be used to inhibit ovarian cancer growth.