Molecular-targeted therapies for ovarian cancer: prospects for the future

HSF1 Pathway Inhibitor Clinical Candidate (CCT361814/NXP800) Developed from a Phenotypic Screen as a Potential Treatment for Refractory Ovarian Cancer and Other Malignancies

CCT251236 1, a potent chemical probe, was previously developed from a cell-based phenotypic high-throughput screen (HTS) to discover inhibitors of transcription mediated by HSF1, a transcription factor that supports malignancy. Owing to its activity against models of refractory human ovarian cancer, 1 was progressed into lead optimization. The reduction of P-glycoprotein efflux became a focus of early compound optimization; central ring halogen substitution was demonstrated by matched molecular pair analysis to be an effective strategy to mitigate this liability. Further multiparameter optimization led to the design of the clinical candidate, CCT361814/NXP800 22, a potent and orally bioavailable fluorobisamide, which caused tumor regression in a human ovarian adenocarcinoma xenograft model with on-pathway biomarker modulation and a clean in vitro safety profile. Following its favorable dose prediction to human, 22 has now progressed to phase 1 clinical trial as a potential future treatment for refractory ovarian cancer and other malignancies.

Angiogenesis and vasculogenic mimicry as therapeutic targets in ovarian cancer

Tumor angiogenesis is an essential process for growth and metastasis of cancer cells as it supplies tumors with oxygen and nutrients. During tumor angiogenesis, many pro-angiogenic factors are secreted by tumor cells to induce their own vascularization via activation of pre-existing host endothelium. However, accumulating evidence suggests that vasculogenic mimicry (VM) is a key alternative mechanism for tumor vascularization when tumors are faced with insufficient supply of oxygen and nutrients. VM is a tumor vascularization mechanism in which tumors create a blood supply system, in contrast to tumor angiogenesis mechanisms that depend on pre-existing host endothelium. VM is closely associated with tumor progression and poor prognosis in many cancers. Therefore, inhibition of VM may be a promising therapeutic strategy and may overcome the limitations of anti-angiogenesis therapy for cancer patients. In this review, we provide an overview of the current anti-angiogenic therapies for ovarian cancer and the current state of knowledge regarding the links between microRNAs and the VM process, with a focus on the mechanism that regulates associated signaling pathways in ovarian cancer. Moreover, we discuss the potential for VM as a therapeutic strategy against ovarian cancer.

Long Noncoding RNA SCAMP1 Targets miR-137/CXCL12 Axis to Boost Cell Invasion and Angiogenesis in Ovarian Cancer

Ovarian cancer (OC) is one of gynecological malignancies that seriously affects women's health. Mounting evidence demonstrated that long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and messenger RNAs (mRNAs) play important roles in various biological processes related to the pathogenesis of OC. This research aimed to investigate the regulatory mechanism of lncRNA SCAMP1/miR-137/CXCL12 (C-X-C motif chemokine ligand 12) axis on OC progression. In this study, we found that SCAMP1 was highly expressed in OC cells, which promoted OC cell invasion and angiogenesis. In addition, our research confirmed that SCAMP1 could bind with miR-137, and SCAMP1 sponged miR-137 to accelerate the progression of OC. We also observed that CXCL12 was a downstream target gene for miR-137, and miR-137 targeted CXCL12 to participate in the regulation of OC. Finally, through TCGA database, we found that SCAMP1 (or CXCL12) was upregulated as well as miR-137 was downregulated in OC tissues, and high (or low) level of them was associated with poor prognosis. miR-137 expression was negatively correlated with SCAMP1 (or CXCL12) expression, and SCAMP1 expression was positively correlated with CXCL12 expression in OC. In summary, our study clarified the role of SCAMP1/miR-137/CXCL12 axis in OC, and this finding may provide a potential therapeutic target of OC.

Long Noncoding RNA FEZF1-AS1 Promotes Proliferation and Inhibits Apoptosis in Ovarian Cancer by Activation of JAK-STAT3 Pathway

BACKGROUND Long noncoding RNAs (lncRNAs) have been acknowledged as important regulators in human cancers, including ovarian cancer. Several reports identified lncRNA FEZF1-AS1 as an oncogene in gastric cancer, colorectal carcinoma, and non-small cell lung cancer (NSCLC). However, the function of FEZF1-AS1 in ovarian cancer remains largely unknown. This study was aimed to investigate the role of FEZF1-AS1 in ovarian cancer. MATERIAL AND METHODS FEZF1-AS1 expression levels in pairs of ovarian cancer tissues and adjacent normal tissues were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Kaplan-Meier curve analysis was used to determine the correlation between FEZF1-AS1 expression and prognosis in ovarian cancer patients. The effects of FEZF1-AS1 knockdown on ovarian cancer cell proliferation, cell-cycle, and apoptosis were analyzed by Cell Counting Kit-8 (CCK8) and Fluorescence activated Cell Sorting (FACS) assays. Western blot was utilized to assess the effect of FEZF1-AS1 on the activation of JAK-STAT3 pathway. RESULTS FEZF1-AS1 was overexpressed in ovarian cancer tissues compared to adjacent normal tissues. Consistently, FEZF1-AS1 expression was also upregulated in ovarian cancer cell lines compared with normal cell line. Furthermore, higher expression of FEZF1-AS1 in ovarian cancer patients contributed to poorer prognosis. FEZF1-AS1 knockdown significantly suppressed the proliferation and promoted apoptosis in ovarian cancer cells. In mechanism, FEZF1-AS1 regulated activation of JAK-STAT3 signaling pathway by modulating STAT3 phosphorylation. Knockdown of FEZF1-AS1 significantly impaired the phosphorylation of STAT3. CONCLUSIONS Our study demonstrated that FEZF1-AS1 exerted an oncogenic role in ovarian cancer via modulating JAK-STAT3 pathway.

Association between RAD51 135 G/C polymorphism and risk of 3 common gynecological cancers: A meta-analysis

AIM

Available data concerning the association between RAD51 135G/C (rs1801320) polymorphism and the risk of 3 common gynecological cancers still could not reach a consensus. Thus, we conducted a meta-analysis to explore the relationship.

METHODS

Several electronic databases and bibliographies of relevant articles were screened to identify the studies up to July 2017. Then a meta-analysis was performed to evaluate the connection between 3 common gynecological tumors' susceptibility and RAD51 135G/C polymorphism in different inheritance models. Simultaneously, we did subgroup analysis and sensitivity analysis if necessary.

RESULTS

A total of 11 articles including 14 studies involving 4097 cases and 5890 controls were included in this meta-analysis. Overall, RAD51 135G/C polymorphism increased the risk of 3 common gynecological tumors. The subgroup analysis stratified by cancer types- endometrial carcinoma (EC) and ovarian cancer (OC)-showed that RAD51 135G/C polymorphism increased the risk of EC: allele model (C vs G: odds ratio [OR] = 4.32, 95% confidence interval [CI] = 2.63-7.10, P < .00001), dominant model (CC + GC vs GG: OR = 2.28, 95% CI = 1.44-3.60, P = .004), recessive model (CC vs GC + GG: OR = 10.27, 95% CI = 14.71-22.38, P < .00001), and homozygous model (CC vs GG: OR = 7.26, 95% CI = 3.59-14.68, P < .00001), but there was no significant association between RAD51 135G/C polymorphism and OC. In the subgroup analysis stratified by source of controls, a significantly increased risk was observed in hospital-based studies. Nevertheless, the data showed RAD51 135G/C polymorphism had no link in population-based studies.

CONCLUSIONS

This meta-analysis suggested that RAD51 135G/C polymorphism was a risk factor for the three common gynecological tumors, especially for EC among hospital-based populations.

Everolimus exhibits anti-tumorigenic activity in obesity-induced ovarian cancer

Everolimus inhibits mTOR kinase activity and its downstream targets by acting on mTORC1 and has anti-tumorigenic activity in ovarian cancer. Clinical and epidemiologic data find that obesity is associated with worse outcomes in ovarian cancer. In addition, obesity leads to hyperactivation of the mTOR pathway in epithelial tissues, suggesting that mTOR inhibitors may be a logical choice for treatment in obesity-driven cancers. However, it remains unclear if obesity impacts the effect of everolimus on tumor growth in ovarian cancer. The present study was aimed at evaluating the effects of everolimus on cytotoxicity, cell metabolism, apoptosis, cell cycle, cell stress and invasion in human ovarian cancer cells. A genetically engineered mouse model of serous ovarian cancer fed a high fat diet or low fat diet allowed further investigation into the inter-relationship between everolimus and obesity in vivo. Everolimus significantly inhibited cellular proliferation, induced cell cycle G1 arrest and apoptosis, reduced invasion and caused cellular stress via inhibition of mTOR pathways in vitro. Hypoglycemic conditions enhanced the sensitivity of cells to everolimus through the disruption of glycolysis. Moreover, everolimus was found to inhibit ovarian tumor growth in both obese and lean mice. This reduction coincided with a decrease in expression of Ki-67 and phosphorylated-S6, as well as an increase in cleaved caspase 3 and phosphorylated-AKT. Metabolite profiling revealed that everolimus was able to alter tumor metabolism through different metabolic pathways in the obese and lean mice. Our findings support that everolimus may be a promising therapeutic agent for obesity-driven ovarian cancers.

Low-dose cisplatin-induced CXCR4 expression promotes proliferation of ovarian cancer stem-like cells

Chemoresistance blocks the efficient treatment of epithelial ovarian cancer, which is the most lethal of all gynecological cancers. Cancer stem cells are believed to be at least partially responsible for the development of chemoresistance. In this study, the effect of cisplatin (CDP) on the enrichment and proliferation of cancer stem-like cells (CSLCs) was investigated, and the underlying mechanisms of action were elucidated. An in vitro anchor-free system was employed to enrich CSLCs from the SKOV3 human epithelial ovarian cancer cell line. Our results showed that treatment with low concentrations of CDP resulted in better-enriched CSLCs, with higher proliferative activities. Low dose of CDP was found to induce the expression of chemokine (C-X-C motif) receptor 4 (CXCR4), which is an important stemness marker in cancer stem cells as well as a promising therapeutic target for ovarian cancer treatment. Results also showed that overexpressed CXCR4 generated chemoresistance. Based on these results, it may be concluded that, at low concentrations, CDP itself contributes to the development of drug resistance. This finding provides novel insight into the mechanisms underlying chemoresistance and has significant therapeutic implications for epithelial ovarian cancer treatment.

Phage display screening identifies a novel peptide to suppress ovarian cancer cells in vitro and in vivo in mouse models

Background

Ovarian cancer is a possibly lethal gynecological malignancy and this study utilized phage display technology to screen and identify peptides that specifically bind to ovarian cancer cells and explored the effects of these peptides on ovarian cancer cells in vitro and in vivo.

Methods

The phage displayed peptide library was used to isolate the peptides binding to and internalizing into the ovarian carcinoma cells. Positive phage clones were characterized with DNA sequencing and bioinformatics analysis and then validated with immunofluorescence. Subsequently, the selected peptides were investigated for their cancer-related functions, including cell adhesion, spreading, motility, and invasion in vitro and in vivo.

Results

Peptide1 read as SWQIGGNwas the positive peptide and showed preferential binding to the target cells. Peptide 1 also inhibited cell proliferation, migration, invasion and adhesion of ovarian cancer HO8910 cells in vitro. In vivo, Peptide 1 led to a lower tumorigenicity of HO8910 cells, which was characterized by the inhibitory effect on tumor growth and metastasis of ovarian cells.

Conclusion

These studies demonstrate that the phage display-identified tumor cell-binding peptide was able to control ovarian cancer cell viability, migration, invasion, and adhesion capacity in vitro as well as tumor growth and metastasis in vivo. Future studies will be aimed at evaluating the clinical efficacy of the peptide SWQIGGN in ovarian cancer patients.

The role of KIF14 in patient-derived primary cultures of high-grade serous ovarian cancer cells

Objective

Previously, it has been shown that KIF14 mRNA is overexpressed in ovarian cancer (OvCa), regardless of histological subtype. KIF14 levels are independently predictive of poor outcome and increased rates of recurrence in serous OvCa patients. Furthermore, it has been shown that KIF14 also controls the in vivo tumorigenicity of OvCa cell lines. In this study, we evaluate the potential of KIF14 as a therapeutic target through selective inhibition of KIF14 in primary high-grade serous patient-derived OvCa cells.

Methods

To assess the dependence of primary serous OvCa cultures on KIF14, protein levels in 11 prospective high grade serous ovarian cancer samples were increased (KIF14 overexpression by transfection) or decreased (anti-KIF14 shRNA) in vitro, and proliferative capacity, anchorage independence and xenograft growth were assessed.

Results

Seven of eleven samples demonstrated increased/decreased in vitro proliferation in response to KIF14 overexpression/knockdown, respectively. When examining in vitro tumorigenicity (colony formation) and in vivo growth (subcutaneous xenografts) in response to KIF14 manipulation, none of the samples demonstrated growth in soft agar (11 samples), or xenograft growth (4 samples).

Conclusions

Although primary high-grade serous OvCa cells may depend on KIF14 for in vitro proliferation we were unable to demonstrate a role for KIF14 on tumorigenicity or develop an in vivo model for assessment. We have, however developed an effective in vitro method to evaluate the effect of target gene manipulation on the proliferative capacity of primary OvCa cultures.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-014-0123-1) contains supplementary material, which is available to authorized users.

Near infrared photoimmunotherapy in the treatment of disseminated peritoneal ovarian cancer

Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of intravenously injected antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein, we evaluate the efficacy of NIR-PIT in a mouse model of disseminated peritoneal ovarian cancer. In vitro and in vivo experiments were conducted with a HER2-expressing, luciferase-expressing, ovarian cancer cell line (SKOV-luc). An antibody-photosensitizer conjugate (APC) consisting of trastuzumab and a phthalocyanine dye, IRDye-700DX, was synthesized (tra-IR700) and cells or tumors were exposed to NIR light. In vitro PIT cytotoxicity was assessed with dead staining and luciferase activity in freely growing cells and in a three-dimensional (3D) spheroid model. In vivo NIR-PIT was performed in mice with tumors implanted in the peritoneum and in the flank and these were assessed by tumor volume and/or bioluminescence. In vitro NIR-PIT-induced cytotoxicity was light dose dependent. Repeated light exposures induced complete tumor cell killing in the 3D spheroid model. In vivo the antitumor effects of NIR-PIT were confirmed by significant reductions in both tumor volume and luciferase activity in the flank model (NIR-PIT vs. control in tumor volume changes at day 10, P = 0.0001; NIR-PIT vs. control in luciferase activity at day 4, P = 0.0237), and the peritoneal model (NIR-PIT vs. control in luciferase activity at day 7, P = 0.0037). NIR-PIT provided effective cell killing in this HER2-positive model of disseminated peritoneal ovarian cancer. Thus, NIR-PIT is a promising new therapy for the treatment of disseminated peritoneal tumors.

The marine-derived fungal metabolite, terrein, inhibits cell proliferation and induces cell cycle arrest in human ovarian cancer cells

The difficulties faced in the effective treatment of ovarian cancer are multifactorial, but are mainly associated with relapse and drug resistance. Cancer stem-like cells have been reported to be an important contributor to these hindering factors. In this study, we aimed to investigate the anticancer activities of a bioactive fungal metabolite, namely terrein, against the human epithelial ovarian cancer cell line, SKOV3, primary human ovarian cancer cells and ovarian cancer stem-like cells. Terrein was separated and purified from the fermentation metabolites of the marine sponge-derived fungus, Aspergillus terreus strain PF26. Its anticancer activities against ovarian cancer cells were investigated by cell proliferation assay, cell migration assay, cell apoptosis and cell cycle assays. The ovarian cancer stem-like cells were enriched and cultured in a serum-free in vitro suspension system. Terrein inhibited the proliferation of the ovarian cancer cells by inducing G2/M phase cell cycle arrest. The underlying mechanisms involved the suppression of the expression of LIN28, an important marker gene of stemness in ovarian cancer stem cells. Of note, our study also demonstrated the ability of terrein to inhibit the proliferation of ovarian cancer stem-like cells, in which the expression of LIN28 was also downregulated. Our findings reveal that terrein (produced by fermention) may prove to be a promising drug candidate for the treatment of ovarian cancer by inhibiting the proliferation of cancer stem-like cells.

Overexpression of CXCR4 is significantly associated with cisplatin-based chemotherapy resistance and can be a prognostic factor in epithelial ovarian cancer

The chemokine receptor 4 (CXCR4) plays an important role in the growth, angiogenesis and metastasis of various cancers, including epithelial ovarian cancer (EOC). However, the correlation between CXCR4 and the clinical response of EOC patients to chemotherapy remains unknown. 124 EOC patients were recruited to assess the relationship between CXCR4 and the response to cisplatin-based chemotherapy. The results showed that patients with a higher CXCR4 expression had a significantly lower chemosensitivity, a poorer progression-free survival and a lower overall survival than those with lower CXCR4 expression. In addition, knockdown of CXCR4 by small interfering RNA suppressed cell proliferation and resulted in G1/S arrest, increased apoptosis and chemosensitivity in both cisplatin-sensitive A2780 cells and cisplatin-resistant cell A2780/cis in vitro. Our data suggest that CXCR4 is one of the key molecules in cisplatin-based chemotherapy for EOC patients and that CXCR4 inhibition is a potential strategy to address the chemoresistance of EOC. [BMB Reports 2014; 47(1): 33-38]

Preferential effect of akt2-dependent signaling on the cellular viability of ovarian cancer cells in response to EGF

OBJECTIVE

Overexpression of the epidermal growth factor receptor (EGFR) is associated with the malignant phenotype in many cancers including ovarian cancer, which leads to increased cell proliferation and survival. In spite of emerging EGFR inhibitors as a potentially useful agent, they are largely ineffective in patients with advanced or recurrent ovarian cancers. Since Akt as a key downstream factor of EGFR is highly activated in some high grade serous ovarian tumors, the augmented Akt activation may attribute to irregular EGFR-mediated signaling observed in ovarian cancer. Here we investigated the differential effect of Akt on the EGF-induced cell viability in a panel of ovarian cancer cell lines.

METHODS

Cellular viability assay and western blot analysis were used to measure cell viability and expression levels of proteins, respectively. Knockdown of Akt was achieved with siRNA and stable transfection of expression vectors was performed.

RESULTS

Cellular viability increased in OVCAR-3 ovarian cancer cells exposed to EGF, but little to no difference was observed in the 5 other ovarian cancer cells including SKOV-3 cells despite of the expression of EGFR. In OVCAR-3 cells, EGF activated Erk and Akt, but an Erk inhibitor had no impact on cellular viability. On the other hand, the EGFR and PI3K inhibitors decreased EGF-induced cellular viability, indicating the involvement of Akt signaling. Although EGF activated Erk in SKOV-3 cells, the Akt activation was very weak as compared to OVCAR-3 cells. Furthermore, we observed a different expression of Akt isoforms: Akt1 was constitutively expressed in all tested ovarian cancer cells, while Akt3 was little expressed. Interestingly, Akt2 was highly expressed in OVCAR-3 cells. Knockdown of Akt2 blocked EGF-induced OVCAR-3 cell viability whereas knockdown for Akt1 and Erk1/2 had no significant effect. Stable transfection of Akt2 into SKOV-3 cells phosphorylated more Akt and enhanced cell viability in response to EGF.

CONCLUSIONS

Akt2-dependent signaling appears to play an important role in EGFR-mediated cellular viability in ovarian cancer and targeting specific Akt isoform may provide a potential therapeutic approach for EGFR-expressing ovarian cancers.

LINE1 and Alu repetitive element DNA methylation in tumors and white blood cells from epithelial ovarian cancer patients

OBJECTIVE

We determined whether DNA methylation of repetitive elements (RE) is altered in epithelial ovarian cancer (EOC) patient tumors and white blood cells (WBC), compared to normal tissue controls.

METHODS

Two different quantitative measures of RE methylation (LINE1 and Alu bisulfite pyrosequencing) were used in normal and tumor tissues from EOC cases and controls. Tissues analyzed included: i) EOC, ii) normal ovarian surface epithelia (OSE), iii) normal fallopian tube surface epithelia (FTE), iv) WBC from EOC patients, obtained before and after treatment, and v) WBC from demographically-matched controls.

RESULTS

REs were significantly hypomethylated in EOC compared to OSE and FTE, and LINE1 and Alu methylation showed a significant direct association in these tissues. In contrast, WBC RE methylation was significantly higher in EOC cases compared to controls. RE methylation in patient-matched EOC tumors and pre-treatment WBC did not correlate.

CONCLUSIONS

EOC shows robust RE hypomethylation compared to normal tissues from which the disease arises. In contrast, RE are generally hypermethylated in EOC patient WBC compared to controls. EOC tumor and WBC methylation did not correlate in matched patients, suggesting that RE methylation is independently controlled in tumor and normal tissues. Despite the significant differences observed over the population, the range of RE methylation in patient and control WBC overlapped, limiting their specific utility as an EOC biomarker. However, our data demonstrate that DNA methylation is deranged in normal tissues from EOC patients, supporting further investigation of WBC DNA methylation biomarkers suitable for EOC risk assessment.

Nucleoside analog inhibits microRNA-214 through targeting heat-shock factor 1 in human epithelial ovarian cancer

The important functions of heat shock factor 1 (HSF1) in certain malignant cancers have granted it to be an appealing target for developing novel strategy for cancer therapy. Here, we report that higher HSF1 expression is associated with more aggressive malignization in epithelial ovarian tumors, indicating that targeting HSF1 is also a promising strategy against ovarian cancer. We found that a nucleoside analog (Ly101-4B) elicits efficient inhibition on HSF1 expression and potent anticancer activity on epithelial ovarian cancer both in vitro and in vivo. Moreover, by targeting HSF1, Ly101-4B inhibits the biogenesis of microRNA-214, which has been revealed to be overexpressed and to promote cell survival in human ovarian epithelial tumors. These findings demonstrate that Ly101-4B is a promising candidate for ovarian cancer therapy, and expand our understanding of HSF1, by revealing that it can regulate microRNA biogenesis in addition to its canonical function of regulating protein-coding RNAs.

Aspirin Blocks EGF-stimulated Cell Viability in a COX-1 Dependent Manner in Ovarian Cancer Cells

Objective: Although aspirin has been associated with a reduction of the risk of cancer when used as a nonsteroidal anti-inflammatory drug, its use to reduce the risk of ovarian cancer is controversial. Ovarian cancer cells usually express high levels of cyclooxygenase-1 (COX)-1. Because aspirin is a rather selective inhibitor of COX-1, the ability of aspirin to reduce the risk of ovarian cancer may be dependent on the level of COX-1 expression in those cells. Furthermore, epidermal growth factor receptor (EGFR) is frequently overexpressed in the malignant phenotype of ovarian cancer leading to increased cell proliferation and survival. Here we investigated if aspirin attenuates EGFR-activated ovarian cancer cell growth in a COX-1 dependent manner.

Methods: Cell viability assays and Western blot analyses were used to determine the effect of aspirin on EGF-stimulated cell proliferation. Gene silencing and gene expression techniques were employed to knockdown or to express COX-1, respectively.

Results: Aspirin inhibited cell viability induced by EGF in a dose dependent manner in COX-1 positive ovarian cancer cells. On the other hand, aspirin had no effect on cell viability in COX-1 negative ovarian cancer cells. In particular, aspirin decreased phosphorylated Akt and Erk activated by EGF. COX-1 silencing in COX-1 positive cells attenuated the inhibitory effect of aspirin on EGF-stimulated cell viability. Furthermore, we developed a COX-1 expressing cell line (SKCOX-1) by stably transfecting COX-1 expression vector into COX-1 negative SKOV-3 cells. SKCOX-1 cells were more responsive to aspirin when compared to cells transfected with empty vector, and decreased EGF-activated Akt and Erk as well as cell viability.

Conclusions: Taken together, aspirin inhibits viability of ovarian cancer cells by blocking phosphorylation of Akt and Erk activated by EGF. Thus it may potentiate the therapeutic efficacy of drugs used to treat COX-1 positive ovarian cancer subsets.

Comprehensive genomic profiling of epithelial ovarian cancer by next generation sequencing-based diagnostic assay reveals new routes to targeted therapies

OBJECTIVE

Targeted next generation sequencing (NGS) was evaluated for its ability to identify unanticipated targetable genomic alterations (GA) for patients with relapsed ovarian epithelial carcinoma (OC).

METHODS

DNA sequencing was performed for 3320 exons of 182 cancer-related genes and 37 introns of 14 genes frequently rearranged in cancer on indexed, adaptor ligated, hybridization-captured libraries using DNA isolated from FFPE sections from 48 histologically verified relapsed OC specimens. The original primary tumor was sequenced in 26 (54%) of the cases and recurrent/metastatic tumor site biopsies were sequenced in 22 (46%) of the cases. Actionability was defined as: GA that predict sensitivity or resistance to approved or standard therapies or are inclusion or exclusion criteria for specific experimental therapies in NCI registered clinical trials.

RESULTS

There were 38 (80%) serous, 5 (10%) endometrioid, 3 (6%) clear cell, 1 mucinous (2%) and 1 (2%) undifferentiated carcinomas. 141 GA were identified with an average of 2.9 GA (range 0-8) per tumor, of which 67 were actionable for an average of 1.4 actionable GA per patient (range 0-5). 33/48 (69%) of OC patient samples harbored at least one actionable GA. Most common GA were TP53 (79%); MYC (25%); BRCA1/2 (23%); KRAS (16.6%) and NF1 (14.5%). One tumor featured an ERBB2 point mutation. One of 3 (33%) of clear cell tumors featured cMET amplification validated by both FISH and IHC.

CONCLUSIONS

NGS assessment of therapy resistant OC identifies an unexpectedly high frequency of GA that could influence targeted therapy selection for the disease.

Stathmin Regulates Hypoxia-Inducible Factor-1α Expression through the Mammalian Target of Rapamycin Pathway in Ovarian Clear Cell Adenocarcinoma

Stathmin, a microtubule-destabilizing phosphoprotein, is highly expressed in ovarian cancer, but the pathophysiological significance of this protein in ovarian carcinoma cells remains poorly understood. This study reports the involvement of stathmin in the mTOR/HIF-1α/VEGF pathway in ovarian clear cell adenocarcinoma (CCA) during hypoxia. HIF-1α protein and VEGF mRNA levels were markedly elevated in RMG-1 cells, a CCA cell line, cultured under hypoxic conditions. Rapamycin, an inhibitor of mTOR complex 1, reduced the level of HIF-1α and blocked phosphorylation of ribosomal protein S6 kinase 1 (S6K), a transcriptional regulator of mTOR, demonstrating that hypoxia activates mTOR/S6K/HIF-1α signaling in CCA. Furthermore, stathmin knockdown inhibited hypoxia-induced HIF-1α and VEGF expression and S6K phosphorylation. The silencing of stathmin expression also reduced Akt phosphorylation, a critical event in the mTOR/HIF-1α/VEGF signaling pathway. By contrast, stathmin overexpression upregulated hypoxia-induced HIF-1α and VEGF expression in OVCAR-3 cells, another CCA cell line. In addition, suppression of Akt activation by wortmannin, a phosphoinositide 3-kinase (PI3K) inhibitor, decreased HIF-1α and VEGF expression. These results illustrate that regulation of HIF-1α through the PI3K/Akt/mTOR pathway is controlled by stathmin in CCA. Our findings point to a new mechanism of stathmin regulation during ovarian cancer.