Future directions in the management of epithelial ovarian cancer

The role of Sox6 and Netrin-1 in ovarian cancer cell growth, invasiveness, and angiogenesis

SOX6 plays important roles in cell proliferation, differentiation, and cell fate determination. It has been confirmed that SOX6 is a tumor suppressor and downregulated in various cancers, including esophageal squamous cell carcinoma, hepatocellular carcinoma, and chronic myeloid leukemia. Netrin-1 is highly expressed in various human cancers and acts as an anti-apoptotic and proangiogenic factor to drive tumorigenesis. The role of SOX6 and netrin-1 in regulating the growth of ovarian tumor cells still remains unclear. Real-time polymerase chain reaction and western blot were used to determine the SOX6 messenger RNA and protein levels, respectively, in ovarian cancer cells and tumor tissues. Stable transfection of SOX6 was conducted to overexpress SOX6 in PA-1 and SW626 cells. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Invasion of ovarian cancer cells and migration of human umbilical vein endothelial cells were confirmed by Transwell assays. To overexpress netrin-1, ovarian cancer cells with SOX6 restoration was transduced with netrin-1 lentiviral particles. PA-1 xenografts in a nude mice model were used to conduct in vivo evaluation of the role of SOX6 and its relationship with netrin-1 in tumor growth and angiogenesis. In this study, we found significantly reduced SOX6 levels in PA-1, SW626, SK-OV-3, and CaoV-3 ovarian cancer cell lines and human tumor tissues in comparison with normal human ovarian epithelial cells or matched non-tumor tissues. SOX6 overexpression by stable transfection dramatically inhibited proliferation and invasion of PA-1 and SW626 cells. Also, conditioned medium from PA-1 and SW626 cells with SOX6 restoration exhibited reduced ability to induce human umbilical vein endothelial cells migration and tube formation compared with conditioned medium from the cells with transfection control. Furthermore, an inverse relationship between SOX6 and netrin-1 expression was observed in PA-1 and SW626 cells. Overexpression of netrin-1 in ovarian cancer cells with forced SOX6 expression remarkably abrogated the inhibitory effect of SOX6 on proliferation, invasion of the cells, and tumor xenograft growth and vascularity in vivo. Human umbilical vein endothelial cell migration and tube formation were enhanced in the conditioned medium from the ovarian cancer cells transduced with netrin-1 lentivirus particles. Our observations revealed that SOX6 is a tumor suppressor in ovarian cancer cells, and SOX6 exerts an inhibitory effect on the proliferation, invasion, and tumor cell-induced angiogenesis of ovarian cancer cells, whereas nerin-1 plays an opposite role and its expression is inversely correlated with SOX6. Moreover, our findings suggest a new role of SOX6 and netrin-1 for understanding the progression of ovarian cancer and have the potential for the development of new diagnosis and treatment strategies for ovarian cancer.

Role of histological type on surgical outcome and survival following radical primary tumour debulking of epithelial ovarian, fallopian tube and peritoneal cancers

Background:

To assess the clinical impact of the two histological types as designated in the proposed model for ovarian tumourigenesis in primary epithelial ovarian, fallopian tube or peritoneal cancer (EOC) patients.

Methods:

All consecutive EOC patients (n=632) after primary tumour debulking in our institution (09/2000–08/2010) were classified into one of two groups: type I tumours (n=100; 15.8%) composed of low-grade serous, low-grade endometrioid, clear cell, mucinous and transitional carcinomas; and Type II tumours (n=532; 84.1%) composed of high-grade serous, high-grade endometrioid, undifferentiated and malignant mixed-mesodermal tumours. Kaplan–Meier and logistic/Cox-regression analyses were performed to assess the impact of histological type on surgical outcome and survival.

Results:

Type II patients had a significantly higher incidence of advanced disease (FIGO III/IV) than Type I patients (79.8% vs 38%, respectively; P<0.001). Median CA125 values (438 vs 93 U ml⁻¹; P=0.001); operative time (258 vs 237 min; P=0.001); and incidence of incomplete tumour resection (34.4% vs 15% P<0.001) were significantly higher in patients with Type II. During a mean follow-up time of 23 months (range: 1–106), 17% of patients with type I vs 34.8% of patients with type II tumours relapsed and/or died (P<0.001). Overall survival (P=0.021) and progression-free survival (P=0.003) were also significantly higher in patients with type I tumours. Multivariate analysis, while identifying postoperative tumour residuals, positive lymph nodes and extrapelvic dissemination as independent predictors of survival, failed to demonstrate any prognostic significance of histological type.

Conclusion:

Type I EOC patients appear to present at earlier stages have significantly higher survival and more optimal surgical outcome compared with type II patients. However, in advanced stages, histology loses significance as an independent prognosticator.

Identification of the coexisting HER2 gene amplification and novel mutations in the HER2 protein-overexpressed mucinous epithelial ovarian cancer

BACKGROUND

Although overexpression, amplification, and somatic mutation of the HER2 gene have been noted in various types of human cancers, we report here for the first time that novel mutations and amplification of the HER2 gene occurred concomitantly in mucinous epithelial ovarian cancer (EOC).

METHODS

Twenty-seven tissue microarray samples from EOC patients were analyzed by immunohistochemistry (IHC) with Dako c-erb-B2 antibody and subsequently were examined by fluorescence in situ hybridization (FISH) with the Abbott PathVysion HER2 DNA Probe Kit. HER2 gene, exon 18-24, encoding a tyrosine kinase domain, was analyzed by polymerase chain reaction (PCR) and direct sequencing.

RESULTS

The FISH-IHC paired results confirmed 19 concordant negative results and 3 concordant positive results. Moreover, all 4 HER2-amplified cases were of the mucinous type, whereas the remaining 23 HER2-nonamplified cases were of the nonmucinous type. The 4 mucinous EOC cases with HER2 gene amplification were selected and further analyzed for HER2 gene mutations. Data revealed that somatic mutations were present in 2 cases (R970W and E971G), but absent in the other 2 cases.

CONCLUSIONS

HER2 protein overexpression correlated significantly with HER2 gene amplification in EOC (P = 0.027). It is surprising that all 4 cases of mucinous EOC showed HER2 gene amplification confirmed by FISH testing. However, we suppose that increasing the number of cases would possibly modify the results. This study also showed that both HER2 gene amplification and somatic mutations are not mutually exclusive in mucinous EOC. Further studies are warranted to investigate the potential role of anti-HER2 therapy.

Role of the 18:1 lysophosphatidic acid-ovarian cancer immunoreactive antigen domain containing 1 (OCIAD1)-integrin axis in generating late-stage ovarian cancer

Chemotherapy resistance in ovarian cancer remains an unsolved problem in caring for women with this disease. We now show that ovarian cancer immunoreactive antigen domain containing 1 (OCIAD1) has higher expression in chemoresistant compared with chemosensitive ovarian cancer cell lines. We have designed a novel secondary cell homing assay (SCHA) to test the ability of cells to withstand chemotherapy and form secondary colonies that could form recurrent disease. OCIAD1 upregulated cells had significantly higher secondary colony-forming ability than had OCIAD1 downregulated cells following treatment with paclitaxel. Additionally, 18:1 lysophosphatidic acid (LPA) increases OCIAD1 expression in a time- and dose-dependent manner. LPA stimulates OCIAD1 serine phosphorylation within two hours of stimulation. Transfection of MKK6 increases OCIAD1 expression but nuclear translocation is inhibited. Inhibition of p38 mitogen-activated protein kinase blocks LPA-induced OCIAD1 expression. Cycloheximide treatment of MKK6-transfected cells does not inhibit OCIAD1 expression, suggesting that MKK6 upregulation is not translationally controlled. OCIAD1 downregulation knocks down LPA-induced cell adhesion to collagen I and laminin 10/11 and specifically inhibits cell attachment to alpha2, alpha5, alphaV, and beta1 integrins. Proteomic studies indicate that OCIAD1 is physically attached to alpha actin 4 and beta actin. Thus, OCIAD1 may play a role in cytoskeletal function which can alter sensitivity to paclitaxel. This is the first study to indicate that OCIAD1 is a key player in generating ovarian cancer recurrence; it is functionally controlled by LPA and MKK6 signaling, and inhibition of OCIAD1 could be an important strategy in the management of recurrent ovarian cancer.

Promising molecular targets in ovarian cancer

PURPOSE OF REVIEW

Clinically and on a molecular level, ovarian cancer is a unique and complex disease. The explosion in potential molecular targets over the last decade has led to the arrival of many novel therapies into oncology. In the present article, we review the most promising of these agents in ovarian cancer.

RECENT FINDINGS

Targeted therapies, such as epidermal growth factor receptor inhibitors, that have worked well in other cancers have shown only moderate success in ovarian cancer, whereas other treatment approaches have yielded surprisingly positive outcomes. An example is anti-vascular endothelial growth factor and proapoptotic strategies, which are effective in both primary and relapsed ovarian cancer. Use of poly (ADP-ribose)-polymerase inhibitors has shown that targeting one form of DNA repair profoundly affects cell survival in those with a hereditary failure to mend DNA damage using another mechanism. This can be extrapolated to patients with sporadic ovarian cancers, with or without the 'BRCAness' phenotype.

SUMMARY

Using targeted agents in ovarian cancer, we are discovering not only how these novel therapies work but are also unveiling the complex 'wiring' of the disease itself, and the interconnections between what were previously believed to be distinct molecular pathways. The addition of targeted agents to our therapeutic armoury is likely to significantly and positively impact on patient survival.

Linear trend in patients with ovarian cancer in period 2001-2008 at Oncology Institute of Vojvodina

Introduction. Ovarian cancer is one of the leading health problems, as it is the underlying cause of disease and deaths of a large number of women around the world. Postmenopausal female population, in whom ovarian carcinoma is most often diagnosed in advanced stages of the disease, is primarily affected. Material and methods. We used data from Hospital Registry for Malignant Neoplasms at Oncology Institute of Vojvodina, for the period from 2001 to 2008, according to which 422 cases of ovarian carcinoma were reported. The obtained data were classified into three groups according to FIGO classification of ovarian malignant neoplasms. The statistical assessment of data employed the method of linear trend and tests of statistical significance (t-test). Results. The results of our study showed that most cases of diagnosed disease were advanced forms of ovarian cancer, FIGO stages II and IV. The linear trend of the reported cases in stage I for the period 2001/2008 showed a descending trend. According to the processed data, in the same period of time, stage II showed an ascending trend, while stages III and IV described together showed a moderate ascending linear trend. Conclusion. A vast majority of cases of ovarian cancer are detected in advanced stages of the disease, which is at the same time the group with the worst prognosis. Special attention should be paid to the group of patients with positive family history, as well as the presence of BRCA1 and BRCA 2 genetic mutations. Currently existing diagnostic procedures have not given good results individually in terms of high sensitivity for diagnosis of early stages.