Evolving concepts in the management of drug resistant ovarian cancer: dose dense chemotherapy and the reversal of clinical platinum resistance

Exploring the Survival Determinants in Recurrent Ovarian Cancer: The Role of Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

BACKGROUND

Recurrent ovarian cancer (ROC) significantly challenges gynecological oncology due to its poor outcomes. This study assesses the impact of cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) on ROC survival rates.

MATERIALS AND METHODS

Conducted at the Medical University of Lublin from April 2011 to November 2022, this retrospective observational study involved 71 patients with histologically confirmed ROC who underwent CRS and subsequent HIPEC.

RESULTS

The median overall survival (OS) was 41.1 months, with 3-year and 5-year survival rates post-treatment of 0.50 and 0.33, respectively. Patients undergoing radical surgery for primary ovarian cancer had a median OS of 61.9 months. The key survival-related factors included the Peritoneal Carcinomatosis Index (PCI) score, AGO score, platinum sensitivity, and ECOG status.

CONCLUSIONS

The key factors enhancing ROC patients' survival include radical surgery, optimal performance status, platinum sensitivity, a positive AGO score, and a lower PCI. This study highlights the predictive value of the platinum resistance and AGO score in patient outcomes, underlining their role in treatment planning. Further prospective research is needed to confirm these results and improve patient selection for this treatment approach.

N6-methyladenosine-modified circPLPP4 sustains cisplatin resistance in ovarian cancer cells via PIK3R1 upregulation

BACKGROUND

Cisplatin (CDDP) is the first-line chemotherapeutic strategy to treat patients with ovarian cancer (OC). The development of CDDP resistance remains an unsurmountable obstacle in OC treatment and frequently induces tumor recurrence. Circular RNAs (circRNAs) are noncoding RNAs with important functions in cancer progression. Whether circRNAs function in CDDP resistance of OC is unclear.

METHODS

Platinum-resistant circRNAs were screened via circRNA deep sequencing and examined using in situ hybridization (ISH) in OC. The role of circPLPP4 in CDDP resistance was assessed by clone formation and Annexin V assays in vitro, and by OC patient-derived xenografts and intraperitoneal tumor models in vivo. The mechanism underlying circPLPP4-mediated activation of miR-136/PIK3R1 signaling was examined by luciferase reporter assay, RNA pull-down, RIP, MeRIP and ISH.

RESULTS

circPLPP4 was remarkably upregulated in platinum resistant OC. circPLPP4 overexpression significantly enhanced, whereas circPLPP4 silencing reduced, OC cell chemoresistance. Mechanistically, circPLPP4 acts as a microRNA sponge to sequester miR-136, thus competitively upregulating PIK3R1 expression and conferring CDDP resistance. The increased circPLPP4 level in CDDP-resistant cells was caused by increased RNA stability, mediated by increased N6-methyladenosine (m6A) modification of circPLPP4. In vivo delivery of an antisense oligonucleotide targeting circPLPP4 significantly enhanced CDDP efficacy in a tumor model.

CONCLUSIONS

Our study reveals a plausible mechanism by which the m6A -induced circPLPP4/ miR-136/ PIK3R1 axis mediated CDDP resistance in OC, suggesting that circPLPP4 may serve as a promising therapeutic target against CDDP resistant OC. A circPLPP4-targeted drug in combination with CDDP might represent a rational regimen in OC.

The DDUP protein encoded by the DNA damage-induced CTBP1-DT lncRNA confers cisplatin resistance in ovarian cancer

Sustained activation of DNA damage response (DDR) signaling has been demonstrated to play vital role in chemotherapy failure in cancer. However, the mechanism underlying DDR sustaining in cancer cells remains unclear. In the current study, we found that the expression of the DDUP microprotein, encoded by the CTBP1-DT lncRNA, drastically increased in cisplatin-resistant ovarian cancer cells and was inversely correlated to cisplatin-based therapy response. Using a patient-derived human cancer cell model, we observed that DNA damage-induced DDUP foci sustained the RAD18/RAD51C and RAD18/PCNA complexes at the sites of DNA damage, consequently resulting in cisplatin resistance through dual RAD51C-mediated homologous recombination (HR) and proliferating cell nuclear antigen (PCNA)-mediated post-replication repair (PRR) mechanisms. Notably, treatment with an ATR inhibitor disrupted the DDUP/RAD18 interaction and abolished the effect of DDUP on prolonged DNA damage signaling, which resulted in the hypersensitivity of ovarian cancer cells to cisplatin-based therapy in vivo. Altogether, our study provides insights into DDUP-mediated aberrant DDR signaling in cisplatin resistance and describes a potential novel therapeutic approach for the management of platinum-resistant ovarian cancer.

Curcumin enhances the anti-cancer efficacy of paclitaxel in ovarian cancer by regulating the miR-9-5p/BRCA1 axis

Background: Patients with late-stage ovarian cancer still have a very poor prognosis due to chemotherapy resistance. Curcumin has been shown to synergistically enhance the therapeutic effects of multiple chemotherapeutic agents, but the potential involvement of curcumin in ovarian cancer is largely unknown. This study aimed to investigate whether curcumin has synergistic anti-cancer effects with paclitaxel in ovarian cancer and its underlying mechanism. Methods: Ovarian cancer cell lines (SKOV3 and A2780) were treated with curcumin, alone or combined with paclitaxel. Cell viability, colony formation, EdU incorporation assays, and flow cytometry were used to assess cell proliferation, apoptosis, and cell cycle progression. The cytotoxic synergistic effect of curcumin and paclitaxel was detected by Calcusyn software. RNA immunoprecipitation assay was used to verify the interaction between miR-9-5p and BRCA1. qRT-PCR and Western blot were performed to detect gene and protein expression. Results: We found that curcumin and paclitaxel synergistically inhibited proliferation and promoted apoptosis in ovarian cancer cells. Furthermore, curcumin and paclitaxel combination resulted in decreased miR-9-5p expression and increased BRCA1 expression. Functionally, miR-9-5p overexpression counteracted the synergistic effect of curcumin and paclitaxel on cell proliferation and apoptosis by targeting BRCA1. Meanwhile, in vivo experiments revealed that curcumin and paclitaxel combination dramatically suppressed the growth of transplanted tumors, while miR-9-5p mimics eliminated the growth inhibition of xenografts induced by the combined treatment. Conclusion: Curcumin enhanced the anti-cancer efficacy of paclitaxel in ovarian cancer by regulating the miR-9-5p/BRCA1 axis. These findings provide strong evidence for clinical investigation of curcumin and paclitaxel combination as a novel strategy for ovarian cancer patients, and identify miR-9-5p and BRCA1 as key targets for regulating sensitivity to this therapy.

circANKRD17(has_circ_0007883) confers paclitaxel resistance of ovarian cancer via interacting with FUS to stabilize FOXR2

Emerging numbers of endogenous circular RNAs (circRNAs) have gained much attention to serve as essential regulators in the carcinogenesis of human cancers. Unfortunately, the occurrence of paclitaxel (PTX) resistance to ovarian cancer remains to be responsible for the poor prognosis. Herein, the aim of our study is to reveal a dysregulation of a particular circRNA, circANKRD17 (has_circ_0007883), and its exact role involving in chemoresistance of ovarian cancer. Expression patterns of circANKRD17 in PTX-resistant ovarian cancer tissues and cell lines was examined using quantitative real-time PCR analysis. Role of circANKRD17 on drug resistance and cell viability was evaluated by CCK-8 assay. Colony formation was subjected to measure cell proliferation. Flow cytometry was employed to evaluate cell cycle either or cell apoptosis. Xenograft models were constructed for further in vivo confirmation. The cicrANKRD17/FUS/FOXR2 axis was demonstrated using bioinformatics analysis, RNA pull-down, as well as RNA immunoprecipitation assays. Dramatically high expressed circANKRD17 observed in ovarian cancer tissues and cells was correlated with PTX resistance, which indicated the poor prognosis. Functionally, knockdown of circANKRD17 decreased PTX resistance via inhibiting cell viability and inducing cell apoptosis. Mechanistically, circANKRD17 interacted with the RNA-binding protein, fused in sarcoma (FUS) to stabilize FOXR2. In summary, our study uncovered a novel machinery of circANKRD17/FUS/FOXR2 referring to ovarian cancer drug sensitivity and tumorigenesis, highlighting a potential strategy for circRNAs in chemoresistance.

MicroRNA-409-5p inhibits cell proliferation, and induces G2/M phase arrest and apoptosis by targeting DLGAP5 in ovarian cancer cells

MicroRNA (miRNA/miR)-409-5p has been reported to be implicated in prostate and breast cancers; however, its functional role in ovarian cancer (OC) remains unclear. Therefore the aim of the present study was to investigate the clinical significance and biological function of miR-409-5p in OC. Here, reverse transcription-quantitative PCR analysis was performed to detect miR-409-5p expression in OC tissues and cell lines. The association between miR-409-5p expression and the clinicopathological characteristics of patients with OC was assessed using the Fisher's exact test. Furthermore, the Cell Counting Kit-8 assay was performed to assess cell proliferation. Cell cycle distribution and apoptosis were evaluated via flow cytometric analysis, and the target gene of miR-409-5p was validated via the dual-luciferase reporter assay. The results demonstrated that miR-409-5p expression was significantly downregulated in OC tissues and cell lines compared with adjacent normal tissues and epithelial cells, respectively. In addition, low miR-409-5p expression was significantly associated with tumor size (P=0.044) and the International Federation of Gynecology and Obstetrics staging system (P=0.005). Notably, overexpression of miR-409-5p suppressed cell proliferation, and induced G₂/M phase arrest and apoptosis of OC cells. Mechanistically, discs large-associated protein 5 (DLGAP5) was identified as a novel target of miR-409-5p, which was negatively regulated by miR-409-5p. DLGAP5 expression was significantly upregulated in OC tissues and cell lines compared with adjacent normal tissues and epithelial cells, respectively. Furthermore, overexpression of DLGAP5 reversed the effects of miR-409-5p on SKOV-3 cell proliferation, and G₂/M phase and apoptosis. Taken together, these results suggest that miR-409-5p acts as a tumor suppressor in OC by modulating DLGAP5 expression.

Notch signaling in female cancers: a multifaceted node to overcome drug resistance

Drug resistance is one of the main challenges in cancer therapy, including in the treatment of female-specific malignancies, which account for more than 60% of cancer cases among women. Therefore, elucidating the underlying molecular mechanisms is an urgent need in gynecological cancers to foster novel therapeutic approaches. Notably, Notch signaling, including either receptors or ligands, has emerged as a promising candidate given its multifaceted role in almost all of the hallmarks of cancer. Concerning the connection between Notch pathway and drug resistance in the afore-mentioned tumor contexts, several studies focused on the Notch-dependent regulation of the cancer stem cell (CSC) subpopulation or the induction of the epithelial-to-mesenchymal transition (EMT), both features implicated in either intrinsic or acquired resistance. Indeed, the present review provides an up-to-date overview of the published results on Notch signaling and EMT- or CSC-driven drug resistance. Moreover, other drug resistance-related mechanisms are examined such as the involvement of the Notch pathway in drug efflux and tumor microenvironment. Collectively, there is a long way to go before every facet will be fully understood; nevertheless, some small pieces are falling neatly into place. Overall, the main aim of this review is to provide strong evidence in support of Notch signaling inhibition as an effective strategy to evade or reverse resistance in female-specific cancers.

Long Non-Coding RNA-Based Functional Prediction Reveals Novel Targets in Notch-Upregulated Ovarian Cancer

Notch signaling is a druggable target in high-grade serous ovarian cancers; however, its complexity is not clearly understood. Recent revelations of the biological roles of lncRNAs have led to an increased interest in the oncogenic action of lncRNAs in various cancers. In this study, we performed in silico analyses using The Cancer Genome Atlas data to discover novel Notch-related lncRNAs and validated our transcriptome data via NOTCH1/3 silencing in serous ovarian cancer cells. The expression of novel Notch-related lncRNAs was down-regulated by a Notch inhibitor and was upregulated in high-grade serous ovarian cancers, compared to benign or borderline ovarian tumors. Functionally, Notch-related lncRNAs were tightly linked to Notch-related changes in diverse gene expressions. Notably, genes related to DNA repair and spermatogenesis showed specific correlations with Notch-related lncRNAs. Master transcription factors, including EGR1, CTCF, GABPα, and E2F4 might orchestrate the upregulation of Notch-related lncRNAs, along with the associated genes. The discovery of Notch-related lncRNAs significantly contributes to our understanding of the complex crosstalk of Notch signaling with other oncogenic pathways at the transcriptional level.

The synergistic effect of eucalyptus oil and retinoic acid on human esophagus cancer cell line SK-GT-4

Background

In order to improve cancer patients' chances of survival, scientists have prioritized finding alternatives to chemotherapy, focusing their efforts on natural sources. The current study investigates the anti-cancer action of retinoic acid and Eucalyptus oil in esophageal cancer and studies their combined effect as well as the cellular pathways that each trigger as part of ongoing research in this field. As a model of esophageal cancer, the SK-GT-4 cancer cell line was treated with a series of concentrations of both materials.

Results

The concentrations of Eucalyptus oil (10, 100, 1000, and 1500 g/mL) and Retinoic acid (5, 100, 150, and 200 M/mL) were used for treatment of cells. The MTT test was used to assess the anti-cancer activity of Eucalyptus oil and Retinoic acid, and qPCR was used to determine cellular pathways. Our findings show that both Eucalyptus oil and Retinoic acid inhibit cancer cell growth significantly. Our findings revealed that the IC50 values for eucalyptus oil were 63 g/mL and 111.3 M l/mL for retinoic acid. Furthermore, the impact was at the level that causes apoptosis. The findings suggested that any herbal substance could act as an inducer of the caspase-9-dependent pathway. The caspase-8-dependent pathway, on the other hand, was restricted to retinoic acid.

Conclusion

Our research discovered that the two chemicals worked together to create a synergistic effect. This synergistic effect could be attributed to a close connection between external and internal apoptotic pathways, which inhibits SK-GT-4 cell growth.

Graphical Abstract

Chronic stress induces platinum and Niraparib resistance in mouse models of ovarian cancer

Resistance to platinum and PARP inhibitors represents a major barrier to the long-term survival of ovarian cancer patients. We aim to explore the potential role of chronic stress in drug resistance in ovarian cancer. Leveraging four ovarian cancer with chronic stress (OCCS) mouse models, we explore the therapeutic efficacy of platinum, Niraparib, and Docetaxel treatment in vivo, and compare the efficacy of these anti-tumor drugs in vitro using cell viability assays. Comparing the transcriptional characteristics in RNA-Seq of OCCS mice with public databases, we analyze the molecular mechanism of chronic stress promoting drug resistance in ovarian cancer. We find that chronic stress is positively correlated with platinum-resistant recurrence in ovarian cancer patients. Chronic stress can induce platinum and Niraparib resistance of ovarian cancer, but it does not affect the therapeutic efficacy of Docetaxel treatment in vivo. And the platinum-resistant cell lines are not sensitive to these anti-tumor drugs, which is different from the result in vivo. Then, we identify several gene networks and their constituent genes that are most significantly associated with chronic stress and drug resistance in ovarian cancer, including the glycolysis pathway and DNA damage. This study develops Niraparib and platinum-resistant in vivo models, reflecting the ability of OCCS mice to reproduce different aspects of human ovarian cancer molecular mechanism, and provides a new theoretical basis for overcoming the double drug resistance of ovarian cancer.

Mitochondrial Dynamics Mediated by DRP1 and MFN2 Contributes to Cisplatin Chemoresistance in Human Ovarian Cancer SKOV3 cells

Cisplatin (DDP) is the first-line chemotherapeutic agent for ovarian cancer. However, the development of DDP resistance seriously influences the chemotherapeutic effect and prognosis of ovarian cancer. It was reported that DDP can directly impinge on the mitochondria and activate the intrinsic apoptotic pathway. Herein, the role of mitochondrial dynamics in DDP chemoresistance in human ovarian cancer SKOV3 cells was investigated. In DDP-resistant SKOV3/DDP cells, mitochondrial fission protein DRP1 was down-regulated, while mitochondrial fusion protein MFN2 was up-regulated. In accordance with the expression of DRP1 and MFN2, the average mitochondrial length was significantly increased in SKOV3/DDP cells. In DDP-sensitive parental SKOV3 cells, downregulation of DRP1 and upregulation of mitochondrial fusion proteins including MFN1,2 and OPA1 occurred at day 2~6 under cisplatin stress. Knockdown of DRP1 or overexpression of MFN2 promoted the resistance of SKOV3 cells to cisplatin. Intriguingly, weaker migration capability and lower ATP level were detected in SKOV3/DDP cells. Respective knockdown of DRP1 in parental SKOV3 cells or MFN2 in SKOV3/DDP cells using siRNA efficiently reversed mitochondrial dynamics, migration capability and ATP level. Moreover, MFN2 siRNA significantly aggravated the DDP-induced ROS production, mitochondrial membrane potential disruption, expression of pro-apoptotic protein BAX and Cleaved Caspase-3/9 in SKOV3/DDP cells. In contrast, DRP1 siRNA alleviated DDP-induced ROS production, mitochondrial membrane potential disruption, expression of pro-apoptotic protein BAX and Cleaved Caspase-3/9 in SKOV3 cells. Thus, these results indicate that mitochondrial dynamics mediated by DRP1 and MFN2 contributes to the development of DDP resistance in ovarian cancer cells, and will also provide a new strategy to prevent chemoresistance in ovarian cancer by targeting mitochondrial dynamics.

A Phase Ib Open-Label, Dose-Escalation Study of NUC-1031 in Combination with Carboplatin for Recurrent Ovarian Cancer

PURPOSE

NUC-1031 is a first-in-class ProTide modification of gemcitabine. In PRO-002, NUC-1031 was combined with carboplatin in recurrent ovarian cancer.

PATIENTS AND METHODS

NUC-1031 was administered on days 1 and 8 with carboplatin on day 1 every 3 weeks for up to six cycles. Four dose cohorts of NUC-1031 (500, 625, and 750 mg/m²) with carboplatin (AUC4 or 5) were investigated. Primary endpoint was recommended phase II combination dose (RP2CD). Secondary endpoints included safety, investigator-assessed objective response rate (ORR), clinical benefit rate (CBR), progression-free survival (PFS), and pharmacokinetics.

RESULTS

A total of 25 women with recurrent ovarian cancer, a mean of 3.8 prior lines of chemotherapy, and a median platinum-free interval of 5 months (range: 7-451 days) were enrolled; 15 of 25 (60%) were platinum resistant, 9 (36%) were partially platinum sensitive, and 1 (4%) was platinum sensitive. Of the 23 who were response evaluable, there was 1 confirmed complete response (4%), 5 partial responses (17%), and 8 (35%) stable disease. The ORR was 26% and CBR was 74% across all doses and 100% in the RP2CD cohort. Median PFS was 27.1 weeks. NUC-1031 was stable in the plasma and rapidly generated high intracellular dFdCTP levels that were unaffected by carboplatin.

CONCLUSIONS

NUC-1031 combined with carboplatin is well tolerated in recurrent ovarian cancer. Highest efficacy was observed at the RP2CD of 500 mg/m² NUC-1031 on days 1 and 8 with AUC5 carboplatin day 1, every 3 weeks for six cycles. The ability to deliver carboplatin at AUC5 and the efficacy of this schedule even in patients with platinum-resistant disease makes this an attractive therapeutic combination.

Long non-coding RNA AFAP1-AS1 facilitates ovarian cancer progression by regulating the miR-107/PDK4 axis

Background

Abnormally expressed in various tumors, long non-coding RNAs (lncRNAs) feature prominently in tumor development, yet little is still known regarding the functional roles of lncRNA AFAP1 antisense RNA 1 (AFAP1-AS1) in ovarian cancer (OC).

Methods

The relative expression levels of lncRNA AFAP1-AS1, microRNA (miR)-107 and pyruvate dehydrogenase kinase isozyme 4 (PDK4) mRNA were assessed by quantitative real-time PCR. PDK4, PCNA and cyclin D1 expression levels were determined using Western blot analysis. Bioinformatics analysis and dual-luciferase gene reporter assay were conducted for identifying and validating the binding sequences between AFAP1-AS1 and miR-107, as well as between miR-107 and PDK4. Cell counting kit-8 assay was employed for detecting cell proliferation. Cell migration and invasion abilities were examined using Transwell assays.

Results

The present study revealed that AFAP1-AS1 expression was elevated in OC cells and tissues. AFAP1-AS1 expression and FIGO stage were positively correlated. AFAP1-AS1 knockdown repressed OC cell proliferation, migration and invasion. AFAP1-AS1 functioned as a sponge of miR-107, and miR-107 reversed the effects of AFAP1-AS1 on OC cells. It was validated that miR-107 was able to bind to PDK4, and AFAP1-AS1 regulated PDK4 expression by competitively binding with miR-107. Additionally, miR-107 modulated OC cell proliferation, migration and invasion via targeting PDK4.

Conclusions

LncRNA AFAP1-AS1 serves as a tumor driver in the pathogenesis of OC via the miR-107/PDK4 axis.

The Emerging Roles of Extracellular Vesicles in Ovarian Cancer

Ovarian cancer (OC) is one of the deadliest gynecological malignancy. Epithelial ovarian cancer (EOC) is its most common form. OC has both, a poor prognosis and a high mortality rate due to the difficulties of early diagnosis, limitation of current treatment and resistance to chemotherapy. Extracellular vesicles (EVs) is a heterogeneous group of cell-derived submicron vesicles, which can be detected in body fluids, and it can be classified into three main types including exosomes, micro-vesicles, and apoptotic bodies. Cancer cells can produce more EVs than healthy cells. Moreover, the contents of these EVs have been found distinctive from each other. It has been considered that EVs shedding from tumor cells may be implicated in clinical applications, such as a tool for tumor diagnosis, prognosis and potential treatment of certain cancers. In this review, we provide a brief description of EVs. in diagnosis, prognosis, treatment, and drug-resistantance of OC. Cancer-related EVs show powerful influences on tumors by various biological mechanisms. However, the contents mentioned above remain in the laboratory stage and there is a lack of large-scale clinical trials, and the maturity of the purification and detection methods is a constraint. In addition, amplification of oncogenes on ecDNA is remarkably prevalent in cancer. It may be possible that ecDNA can be encapsulated in EVs and thus detected by us. In summary, much more research on EVs needs to be performed to reveal breakthroughs in OC and to accelerate the process of its application in clinic.

HDAC6 Degradation Inhibits the Growth of High-Grade Serous Ovarian Cancer Cells

Simple Summary

The objective of this study was, firstly, to investigate the relationship between Histone deacetylase 6 (HDAC6) expression and survival in patients with ovarian cancer and, secondly, to test the effects of histone deacetylase 6 (HDAC6) inhibition on ovarian cancer cells in vitro. A meta-analysis of the correlation between HDAC6 gene expression and survival was performed on 3573 ovarian tumors from 19 datasets showed that high HDAC6 gene expression was associated with a decreased risk of death. Knockdown of HDAC6 gene expression with small interfering RNA (siRNA) and protein expression with a HDAC6 targeting protein degrader decreased ovarian cell proliferation, migration, and viability. Conversely, the selective inhibition of HDAC6 catalytic activity did not produce a robust inhibition of HDAC6 protein function. In summary, we demonstrated, for the first time, that HDAC6 over-expression in ovarian cancers is a favorable prognostic marker. We provide evidence to suggest that inhibition of HDAC6 catalytic activity has limited efficacy as a monotherapy in ovarian cancers.

Abstract

Histone deacetylase 6 (HDAC6) is a unique histone deacetylating enzyme that resides in the cell cytoplasm and is linked to the modulation of several key cancer related responses, including cell proliferation and migration. The promising anti-cancer response of the first-generation HDAC6 catalytic inhibitors continues to be assessed in clinical trials, although its role in high grade serous ovarian cancer is unclear. This study investigated HDAC6 tumor expression by immunohistochemistry in high-grade serous ovarian cancer (HGSOC) tissue samples and a meta-analysis of HDAC6 gene expression in ovarian cancer from publicly available data. The pharmacological activity of HDAC6 inhibition was assessed in a patient-derived model of HGSOC. HDAC6 was found to be highly expressed in HGSOC tissue samples and in the patient-derived HGSOC cell lines where higher HDAC6 protein and gene expression was associated with a decreased risk of death (hazard ratio (HR) 0.38, (95% confidence interval (CI), 0.16–0.88; p = 0.02); HR = 0.88 (95% CI, 0.78–0.99; p = 0.04)). Similarly, the multivariate analysis of HDAC6 protein expression, adjusting for stage, grade, and cytoreduction/cytoreductive surgery was associated with a decreased risk of death (HR = 0.19 (95% CI, 0.06–0.55); p = 0.002). Knock-down of HDAC6 gene expression with siRNA and protein expression with a HDAC6 targeting protein degrader decreased HGSOC cell proliferation, migration, and viability. Conversely, the selective inhibition of HDAC6 with the catalytic domain inhibitor, Ricolinostat (ACY-1215), inhibited HDAC6 deacetylation of α-tubulin, resulting in a sustained accumulation of acetylated α-tubulin up to 24 h in HGSOC cells, did not produce a robust inhibition of HDAC6 protein function. Inhibition of HGSOC cell proliferation by ACY-1215 was only achieved with significantly higher and non-selective doses of ACY-1215. In summary, we demonstrated, for the first time, that HDAC6 over-expression in HGSOC and all ovarian cancers is a favorable prognostic marker. We provide evidence to suggest that inhibition of HDAC6 catalytic activity with first generation HDAC6 inhibitors has limited efficacy as a monotherapy in HGSOC.

Circular RNA circTNPO3 Regulates Paclitaxel Resistance of Ovarian Cancer Cells by miR-1299/NEK2 Signaling Pathway

Circular RNAs (circRNAs) were recently reported to be involved in the pathogenesis of ovarian cancer (OC); however, the molecular mechanisms of circRNAs in tumor progression and paclitaxel (PTX) resistance of OC remain largely undetermined. Here, we focused on circTNPO3 (hsa_circ_0001741), which is located on chromosome 7 (chr7): 128655032–128658211 and derived from TNPO3 gene, and thus we termed as circTNPO3. By microarray and qRT-PCR we identified circTNPO3 to be dramatically high expressed in OC samples and correlated with PTX resistance. Functionally, knockdown of circTNPO3 enhanced cell sensitivity to PTX via promoting PTX-induced apoptosis in vitro and in vivo. In mechanism, circTNPO3 acted as a sponge for microRNA-1299 (miR-1299), and NEK2 (NIMA-related kinase 2) was revealed to be target gene of miR-1299. Subsequently, functional assays illustrated that the oncogenic effects of circTNPO3 were attributed to the regulation of miR-1299/NEK2 axis. In conclusion, circTNPO3 contributed to PTX resistance of OC cells at least partly through upregulating NEK2 expression by sponging miR-1299. circTNPO3/miR-1299/NEK2 signaling pathway might play vital roles in the tumorigenesis and chemoresistance of OC.

Comparisons of Clinical Outcomes in Women with Advanced Ovarian Cancer Treated with Frontline Intraperitoneal versus Dose-Dense Platinum/Paclitaxel Chemotherapy without Bevacizumab

Background: We aimed to compare the clinical outcomes between intraperitoneal chemotherapy and dose-dense chemotherapy for the frontline treatment of advanced ovarian, fallopian tube and primary peritoneal cancer in women not receiving bevacizumab. Methods: All consecutive women with stage II~IV cancer treated with either frontline intraperitoneal or dose-dense platinum/paclitaxel chemotherapy and not receiving bevacizumab between March 2006 and June 2019 were reviewed. Results: A total of 50 women (intraperitoneal group, n = 22; dose-dense group, n = 28) were reviewed. Median progression-free survival (32.6 months versus 14.2 months; adjusted hazard ratio = 0.38; 95% CI = 0.16 to 0.90, p = 0.03) and overall survival (not reached versus 30.7 months; adjusted hazard ratio = 0.23, 95% CI = 0.07 to 0.79, p = 0.02) were significantly higher in the intraperitoneal group than in the dose-dense group. A multivariable Cox proportional-hazards model also indicated that the number of frontline chemotherapy cycles (adjusted hazard ratio = 0.66, 95% CI 0.47 to 0.94, p = 0.02) was a predictor of better overall survival. Nausea/vomiting and nephrotoxicity occurred more frequently in the intraperitoneal group (p = 0.02 and <0.0001, respectively). Conclusions: Intraperitoneal chemotherapy seems to be superior in progression free survival and overall survival to dose-dense chemotherapy in the frontline treatment of women with optimally resected advanced ovarian, fallopian tube or primary peritoneal cancer and not receiving bevacizumab.

circCELSR1 (hsa_circ_0063809) Contributes to Paclitaxel Resistance of Ovarian Cancer Cells by Regulating FOXR2 Expression via miR-1252

Ovarian cancer is the malignant tumor of the female reproductive system with the highest fatality rate. Tolerance to chemotherapeutic drugs such as paclitaxel (PTX) occurring in the very early stage is one of the important factors of the poor prognosis of ovarian cancer. Herein, we aim to study the dysregulation of a particular circular RNA (circRNA), circCELSR1 (hsa_circ_0063809), and its role in the progression and PTX resistance of ovarian cancer. The high expression of circCELSR1 in PTX-resistant tissues of ovarian cancer and PTX-resistant ovarian cancer cells (SKOV3/PTX and HeyA-8/PTX) was determined by microarray analyses and quantitative real-time PCR. Cell Counting Kit-8 (CCK-8) assays were performed to investigate the effect of circCELSR1 on PTX sensitivity of ovarian cancer cells. Flow cytometer assays were used to detect cell cycle and apoptosis of ovarian cancer cells. The effect of circCELSR1 on ovarian cancer cells was assessed in vitro and in vivo. The microRNA (miRNA) sponge mechanism of circRNAs was demonstrated using dual-luciferase reporter and RNA immunoprecipitation assays. By microarray (5 PTX-resistant ovarian cancer tissues νs 5 PTX-sensitive ovarian cancer tissues) and qRT-PCR (36 normal ovarian tissues and ovarian cancer tissues) we identified circCELSR1 to be dramatically highly expressed in ovarian cancer samples and correlated with PTX resistance. Compared with sensitive cell lines, circCELSR1 was also highly expressed in PTX-resistant ovarian cancer cell lines, and circCELSR1 silencing enhanced PTX-induced cytotoxicity in ovarian cancer cells. Meanwhile, the inhibition of circCELSR1 also caused ovarian cancer cell G₀/G₁ arrest and an increase in apoptosis. In vivo studies revealed that circCELSR1 was stably inhibited in a xenograft mouse model and inhibited the growth of ovarian cancer. Furthermore, we demonstrated that circCELSR1 acts as a sponge for miR-1252 and verified that forkhead box 2 (FOXR2) is a novel target of miR-1252. In this study, we explored the specific mechanisms of PTX resistance and tumor progress of ovarian cancer due to circCELSR1; presented the circCELSR1-miR-1252-FOXR2 axis and its role in ovarian cancer drug sensitivity and progression; and suggest that the results may provide an experimental basis for clinical application.

Comparison between weekly versus 3-weekly paclitaxel in combination with carboplatin as neoadjuvant chemotherapy in advanced ovarian cancer

Objective

To compare the efficacy and toxicity of dose-dense weekly paclitaxel and 3-weekly carboplatin (ddPC) as neoadjuvant chemotherapy (NAC) with the standard 3-weekly regimen.

Methods

A retrospective study of patients diagnosed with stage IIIc and IV ovarian cancer who received at least one cycle of NAC followed by interval debulking surgery between August 2015 and January 2018 was conducted. Patient characteristics, clinical and pathological response to NAC, surgical and survival outcome, and adverse event were compared.

Results

A total of 23 patients in the ddPC group and 50 patients in the standard group received a median of 3 cycles of NAC. Rate of grade ≥3 neutropenia was significantly higher in the ddPC group than the standard (82.6% vs. 22.0%, p<0.001). Patients in the ddPC group underwent dose-reduction more frequently (34.8% vs. 4.00%, p=0.001). Normalization of cancer antigen-125 post-NAC occurred more frequently in the ddPC group (73.9% vs. 46.0%, p=0.030). No residual disease rate (43.5% vs. 60.0%, p=0.188) and chemotherapy response score of 3 (34.8% vs. 26.0%, p=0.441) were not statistically different between two groups. There was no statistical difference in progression free survival (PFS) at 2 years (36.3% vs. 28.4%, p=0.454). Cox proportional hazard model showed that ddPC was not a significant determinant of PFS (p=0.816).

Conclusion

There was no difference between both regimens in terms of NAC response and survival outcomes. However, ddPC group showed higher hematologic toxicity requiring dose reduction.

Sequential combination of cisplatin with eugenol targets ovarian cancer stem cells through the Notch-Hes1 signalling pathway

Background

Ovarian carcinomas are the deadliest gynecological malignancies owing to their high rate of recurrence and high resistance to platinum-based chemotherapy. Recent studies have shown platinum-dependent enrichment of ovarian tumors with side population as well as cancer stem cells, which are highly resistant to the treatment. To overcome this treatment-limiting factor, we sought to combine cisplatin with eugenol, a natural substance known to have anti-cancer effects.

Methods

The efficiency of combining cisplatin with eugenol was first tested in vitro on two ovarian cancer cell lines SKOV3 and OV2774 using the WST1 and the flow cytometry techniques. The effect of this combination on ovarian cancer stem cells was determined by the tumorsphere formation assay, while the implication of the Notch pathway was evaluated post-ectopic expression of the Hes1 gene. The resulting changes in the expression of several markers was assessed by immunoblotting, immunofluorescence as well as quantitative RT-PCR. Cell sorting was also used to isolate specific ovarian cancer sub-population of cells. Furthermore, tumor-bearing mouse models were utilized to prove the potential therapeutic value of the cisplatin/eugenol combination treatment in vivo.

Results

We have shown that adding eugenol to cisplatin-treated ovarian cancer cells synergistically inhibited their growth and survival through induction of apoptosis. Importantly, this sequential inhibition strongly reduced the proportion of side population cells and suppressed cisplatin-dependent enrichment in ovarian cancer stem cells. Additionally, while increase in the level of Hes1 promoted stemness and enhanced resistance to cisplatin, cisplatin/eugenol cotreatment inhibited the Notch-Hes1 pathway and strongly downregulated the drug resistance ABC transporter genes. These findings were confirmed in vivo by showing that cisplatin/eugenol cotherapy inhibited tumor growth in animals, reduced the proportion and self-renewal capacities of cancer stem cells and significantly improved disease-free survival of tumor-bearing animals compared with either therapy alone.

Conclusions

These results indicate that cisplatin/eugenol sequential combination could be of great therapeutic value for ovarian cancer patients through targeting the Notch-Hes1 pathway and the consequent elimination of the resistant cancer stem cells.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1360-3) contains supplementary material, which is available to authorized users.

Long non-coding RNA GAS5 inhibits DDP-resistance and tumor progression of epithelial ovarian cancer via GAS5-E2F4-PARP1-MAPK axis

Background

Epithelial ovarian cancer (EOC) is the malignant tumor of the female reproductive system with the highest fatality rate. Tolerance of chemotherapeutic drugs like cisplatin (DDP) occurring in very early stage is one of the important factors of the poor prognosis of epithelial ovarian cancer. Here we aim to study the dysregulation of a particular long noncoding RNA, lncRNA GAS5, and its role in EOC progression.

Methods

The low expression of lncRNA GAS5 in EOC tissues and OC cell lines was determined by microarray analyses and Real-Time qPCR. Flow cytometer assays were used to detect cell cycle and apoptosis of OC cells. CCK8 assay were performed to investigate the DDP sensitivity of OC cells. Western blot was carried out to detect cell growth markers, apoptotic markers, PARP1, E2F4, MAPK pathway protein expression and other protein expression in OC cell lines. The binding of GAS5 and E2F4 were proved by RNA pull-down and RIP assay. The effect of E2F4 on PARP1 were determined by CHIP-qPCR assay and luciferase reporter assay. The effect of lncRNA GAS5 on OC cells was assessed in vitro and in vivo.

Results

By microarray (3 EOC tissues νs. 3 normal ovary tissues) and RT- qPCR (53 EOC tissues νs. 10 normal ovary tissues) we identified lncRNA GAS5 to be dramatically low expressed in EOC samples and correlated with prognosis. Compared with sensitive cell lines, GAS5 was also low expressed in DDP resistant OC cell lines, and over-expression of GAS5 significantly enhanced the sensitivity of OC cells to DDP in vivo and in vitro. Meanwhile the over-expression of GAS5 also caused OC cells G0/G1 arrest and apoptosis increase. Mechanistically, GAS5 might regulate PARP1 expression by recruiting the transcription factor E2F4 to its promoter, and then affect the MAPK pathway activity. Due to the 5’TOP structure, GAS5 could be regulated by transcription inhibitor rapamycin in OC cells.

Conclusion

Here we explored the specific mechanisms of EOC cisplatin resistance and tumor progress due to lncRNA-GAS5, presented the GAS5-E2F4-PARP1-MAPK axis and its role in OC drug-sensitivity and progression for the first time, and the results may provide experimental basis for clinical application.

Nanoparticles based on retinoic acid caped with ferrocenium: a novel synthesized targetable nanoparticle both with anti-cancer effect and drug loading capacity

To date, there is an urgent need for cancer treatment to improve in many ways in order to successfully cure all cancers. Retinoic acid (RA) is a promising anti-cancer drug through influencing cancer stem cells (CSCs). Taxol is a chemotherapy drug for many cancers. To increase the anti-cancer effects of RA and taxol, we created a novel RA nanoparticle, FCRAN, which has the ability of carrying a second anti-cancer drug, taxol, using nanotechnological methods. The results of this study demonstrated that this RA nanoparticle was water-soluble and retained the same effects as RA on cancer cells, such as inhibiting the proliferation of CSCs, inducing the differentiation of CSCs, and enhancing the sensitivity of CSCs to chemotherapeutic drugs. In addition, this RA nanoparticle can be used to carry a second anticancer drug, taxol, to become FCRAN/T and synergistically enhance the anti-cancer effects of both drugs in vivo. Interestingly, the FCRAN/T is a targetable anti-cancer nanoparticle in the presence of higher levels of glutathione (GSH) in cancer cells. Our results demonstrate that our novel synthesized nanoparticles not only retain the RA functions, but can also carry a second anticancer drug to play a synergistic anticancer role with good water solubility, in particular FCRAN/T can target cancer cells. Therefore, our novel synthesized targetable anti-cancer nanoparticles have a better application prospect than that of RA or taxol alone.

A retinoic acid nanoparticle with the ability of carrying a second anti-cancer drug, taxol, was developed. The anti-cancer nanoparticles were shown to have a better application prospect than that of RA or taxol alone.

Loss of RBMS3 Confers Platinum Resistance in Epithelial Ovarian Cancer via Activation of miR-126-5p/β-catenin/CBP signaling

PURPOSE

The development of resistance to platinum-based chemotherapy remains the unsurmountable obstacle in cancer treatment and consequently leads to tumor relapse. This study aims to investigate the mechanism by which loss of RBMS3 induced chemoresistance in epithelial ovarian cancer (EOC).

EXPERIMENTAL DESIGN

FISH and IHC were used to determine deletion frequency and expression of RBMS3 in 15 clinical EOC tissues and 150 clinicopathologically characterized EOC specimens. The effects of RBMS3 deletion and CBP/β-catenin antagonist PRI-724 in chemoresistance were examined by clone formation and Annexin V assays in vitro, and by intraperitoneal tumor model in vivo. The mechanism by which RBMS3 loss sustained activation of miR-126-5p/β-catenin/CBP signaling and the effects of RBMS3 and miR-126-5p competitively regulating DKK3, AXIN1, BACH1, and NFAT5 was explored using CLIP-seq, RIP, electrophoretic mobility shift, and immunoblotting and immunofluorescence assays.

RESULTS

Loss of RBMS3 in EOC was correlated with the overall and relapse-free survival. Genetic ablation of RBMS3 significantly enhanced, whereas restoration of RBMS3 reduced, the chemoresistance ability of EOC cells both in vitro and in vivo. RBMS3 inhibited β-catenin/CBP signaling through directly associating with and stabilizing multiple negative regulators, including DKK3, AXIN1, BACH1, and NFAT5, via competitively preventing the miR-126-5p-mediated repression of these transcripts. Importantly, cotherapy of CBP/β-catenin antagonist PRI-724 induced sensitization of RBMS3-deleted EOC to platinum therapy.

CONCLUSIONS

Our results demonstrate that genetic ablation of RBMS3 contributes to chemoresistance and PRI-724 may serve as a potential tailored treatment for patients with RBMS3-deleted EOC.

53BP1 inhibits the migration and regulates the chemotherapy resistance of ovarian cancer cells

The major problems faced during the treatment of ovarian cancer are metastasis and the development of intrinsic or acquired drug resistance. The present study assessed whether tumor protein p53 binding protein 1 (53BP1) regulated migration and modulated chemotherapy resistance in SKOV3 cells and identified proteins associated with the molecular mechanisms underlying this coordinate regulation. SKOV3 cells were transfected using a 53BP1-expressing vector, which induced 53BP1 overexpression. The migration of the transfected cells was observed using a Transwell assay. The expression of matrix metalloproteinase (MMP)-2 and MMP-9 were assayed using gelatin zymography. In addition, the effects of 53BP1 on the chemosensitivity of SKOV3 cells to cisplatin were evaluated using MTT and western blot assays. Compared with the control, the average number of migrating SKOV3/pLPC-53BP1 cells was decreased from 230±58 to 45±12 (P<0.05) and the protein expression of MMP-9 was significantly inhibited. However, the chemosensitivity of SKOV3/pLPC-53BP1 to cisplatin decreased significantly: Cisplatin half maximal inhibitory concentration (IC⁵⁰) for SKOV3/pLPC-53BP1=7.58±0.51 µg/ml; cisplatin IC⁵⁰ for control=2.98±0.27 µg/ml (P<0.01). Decreased chemosensitivity to cisplatin may be associated with increased expression of phosphorylated-protein kinase B and cyclin dependent kinase 2 and with decreased expression of p21 and the B cell lymphoma (Bcl)-2 associated X/Bcl-2 ratio. The results of the present study demonstrated that 53BP1 may inhibit migration but upregulate chemoresistance to cisplatin in SKOV3 cells.

Aqueous extract of Sapindus mukorossi induced cell death of A549 cells and exhibited antitumor property in vivo

Sapindus mukorossi is a deciduous plant and has recently been recognized to have anticancer property. In the present study, we discovered that S. mukorossi leaf and stem aqueous extract (SaM) contained two polysaccharides mainly made of myo-inositol, galactose, glucose, and fructose and the aim of this study was to investigate the antitumor property the aqueous extract SaM. In vitro treatment of SaM diminished proliferative potential of lung adenocarcinomic cells and induced intracellular oxidative stress, as well as necrotic cell death. Moreover, exposure to SaM attenuated cell migration, demonstrating the effectiveness at reducing invasive property of malignant lung cells. Gene and protein expression studies indicated that SaM treatment altered the expression of proliferation/survival modulator NF-κB, tumor growth modulator ERK2, metastasis-associated molecules MMP9/12, and tumor suppressor p53 in A549 cells. Using model animals bearing Lewis lung cancer cell LL/2, we demonstrated that SaM was antitumoral and did not induce any undesired organ damage, immunotoxicity, and off-target inflammation. This work, to our knowledge, is the first study documents the antitumor bioactivity of aqueous extract riched in polysaccharides from S. mukorossi and provides insights into the potential pharmacological application of SaM as antitumor agent against lung cancer.

Resistance to glucose starvation as metabolic trait of platinum-resistant human epithelial ovarian cancer cells

Deregulated glucose metabolism is observed in cancer but whether this metabolic trait influences response to or is modulated by cytotoxic drugs is unknown. We show here that tumor cells from epithelial ovarian cancer (EOC) patients can be categorized, according to their in vitro viability under glucose starvation, into glucose deprivation-sensitive (glucose-addicted, GA) and glucose deprivation-resistant (glucose non-addicted, GNA). When EOC cells were cultured in the absence of glucose, all samples from platinum (PLT)-sensitive patients felt into the GA group; they disclosed higher expression of glucose metabolism enzymes, higher proliferation rates and in vitro sensitivity to PLT. Moreover, GA patients showed reduced multi-drug resistance pump expression and autophagy, compared to GNA samples. The close association between PLT sensitivity and glucose metabolic profile was confirmed in a xenograft model, where a stringent parallelism between PLT sensitivity/resistance and glucose metabolism was identified. Finally, in a cohort of naïve EOC patients categorized as GA or GNA at diagnosis, Kaplan Meier curves showed that the GA phenotype was associated with significantly better progression-free survival, compared to GNA patients.

Evaluation of the cytotoxicity of the Bithionol-paclitaxel combination in a panel of human ovarian cancer cell lines

Previously, Bithionol (BT) was shown to enhance the chemosensitivity of ovarian cancer cell lines to cisplatin treatment. In the present study, we focused on the anti-tumor potential of the BT-paclitaxel combination when added to a panel of ovarian cancer cell lines. This in vitro study aimed to 1) determine the optimum schedule for combination of BT and paclitaxel and 2) assess the nature and mechanism(s) underlying BT-paclitaxel interactions. The cytotoxic effects of both drugs either alone or in combination were assessed by presto-blue cell viability assay using six human ovarian cancer cell lines. Inhibitory concentrations to achieve 50% cell death (IC₅₀) were determined for BT and paclitaxel in each cell line. Changes in levels of cleaved PARP, XIAP, bcl-2, bcl-xL, p21 and p27 were determined via immunoblot. Luminescent and colorimetric assays were used to determine caspases 3/7 and autotaxin (ATX) activity. Cellular reactive oxygen species (ROS) were measured by flow cytometry. Our results show that the efficacy of the BT-paclitaxel combination depends upon the concentrations and sequence of addition of paclitaxel and BT. Pretreatment with BT followed by paclitaxel resulted in antagonistic interactions whereas synergistic interactions were observed when both drugs were added simultaneously or when cells were pretreated with paclitaxel followed by BT. Synergistic interactions between BT and paclitaxel were attributed to increased ROS generation and enhanced apoptosis. Decreased expression of pro-survival factors (XIAP, bcl-2, bcl-xL) and increased expression of pro-apoptotic factors (caspases 3/7, PARP cleavage) was observed. Additionally, increased expression of key cell cycle regulators p21 and p27 was observed. These results show that BT and paclitaxel interacted synergistically at most drug ratios which, however, was highly dependent on the sequence of the addition of drugs. Our results suggest that BT-paclitaxel combination therapy may be effective in sensitizing ovarian cancer cells to paclitaxel treatment, thus mitigating some of the toxic effects associated with high doses of paclitaxel.

Preoperative prognostic nutritional index is a powerful predictor of prognosis in patients with stage III ovarian cancer

Many established inflammation- and nutrition-related factors have been investigated as potential independent prognostic factors in various cancers, including the C-reactive protein/albumin ratio (CAR), lymphocyte/monocyte ratio (LMR), modified Glasgow prognostic score (mGPS), body mass index (BMI), and prognostic nutritional index (PNI). This study was performed to estimate the prognostic value of these factors in predicting survival and platinum resistance in ovarian cancer (OC), especially according to stage. Kaplan-Meier and multivariate analyses were performed to plot the survival curve and determine the independent prognostic factors. Additionally, the area under the receiver operating characteristic curve (AUC) was used to predict platinum resistance and prognosis by comparing the predictive ability of PNI and cancer antigen (CA)-125. In all patients, decreased PNI was significantly associated with platinum resistance and poor overall survival (OS) and progression-free survival (PFS). Regarding tumor stage, decreased PNI was significantly associated with poor PFS and OS only in stage III OC. Furthermore, the PNI also showed a significantly higher AUC value than CA-125 for predicting mortality and platinum resistance in all OC patients, but not in stage III patients. In conclusion, decreased PNI is a powerful predictor of a poor prognosis in OC, and especially for stage III cases.

Exploration of the sequential gene changes in epithelial ovarian cancer induced by carboplatin via microarray analysis

The purpose of the current study was to explore the carboplatin-induced sequential changes in gene expression and screen out key genes, which were associated with effects of carboplatin on epithelial ovarian cancer (EOC). The microarray dataset GSE13525 was downloaded from the Gene Expression Omnibus database, including 6 EOC cell samples separately treated with carboplatin at 24, 30 and 36 h (case group), and 6 samples treated with phosphate-buffered saline at the same time points (control group). A total of 3 sets of differentially expressed genes (DEGs) were respectively identified in case samples at 24, 30 and 36 h compared with the control group via the Limma package, and separately recorded as DEG-24, DEG-30 and DEG-36. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the overlapped DEGs were performed via the Database for Annotation, Visualization and Integrated Discovery. The protein-protein interaction (PPI) network was constructed and analyzed by Cytoscape software. In addition, the survival curves were drawn to illustrate the association between the expression levels of certain critical genes and the prognosis of EOC. A total of 170, 605 and 1043 DEGs were separately obtained in DEG-24 DEG-30 and DEG-36, and 110 overlaps were identified. The overlaps were enriched in 77 GO terms and 3 KEGG pathways. A total of 152 pairs were involved in the PPI network, and the abnormal expression levels (high or low) of c-Jun and cyclin B1 (CCNB1) would reduce the survival time of patients with EOC. The study indicated that c-Jun and CCNB1 may be the prognostic biomarkers of EOC treated with carboplatin, and certain pathways (such as p53 signaling pathway, cell cycle and mitogen-activation protein kinase signaling pathway) may be involved in carboplatin-resistant EOC.

WNT antagonists exhibit unique combinatorial antitumor activity with taxanes by potentiating mitotic cell death

The WNT pathway mediates intercellular signaling that regulates cell fate in both normal development and cancer. It is widely appreciated that the WNT pathway is frequently dysregulated in human cancers through a variety of genetic and epigenetic mechanisms. Targets in the WNT pathway are being extensively pursued for the development of new anticancer therapies, and we have advanced two WNT antagonists for clinical development: vantictumab (anti-FZD) and ipafricept (FZD8-Fc). We examined the antitumor efficacy of these WNT antagonists in combination with various chemotherapies in a large set of patient-derived xenograft models. In responsive models, WNT blockade led to profound synergy with taxanes such as paclitaxel, and the combination activity with taxanes was consistently more effective than with other classes of chemotherapy. Taxane monotherapy increased the frequency of cells with active WNT signaling. This selection of WNT-active chemotherapy-resistant tumorigenic cells was prevented by WNT-antagonizing biologics and required sequential dosing of the WNT antagonist followed by the taxane. The WNT antagonists potentiated paclitaxel-mediated mitotic blockade and promoted widespread mitotic cell death. By blocking WNT/β-catenin signaling before mitotic blockade by paclitaxel, we found that this treatment effectively sensitizes cancer stem cells to taxanes. This combination strategy and treatment regimen has been incorporated into ongoing clinical testing for vantictumab and ipafricept.

B7-H3-targeted 212Pb radioimmunotherapy of ovarian cancer in preclinical models

INTRODUCTION

Novel therapies that effectively kill both differentiated cancer cells and cancer initiating cells (CICs), which are implicated in causing chemotherapy-resistance and disease recurrence, are needed to reduce the morbidity and mortality of ovarian cancer. These studies used monoclonal antibody (mAb) 376.96, which recognizes a B7-H3 epitope expressed on ovarian cancer cells and CICs, as a carrier molecule for targeted α-particle radioimmunotherapy (RIT) in preclinical models of human ovarian cancer.

METHODS

mAb 376.96 was conjugated to the chelate 2-(4-isothiocyanotobenzyl)-1,4,7,10-tetraaza-1,4,7,10-tetra-(2-carbamoylmethyl)-cyclododecane (TCMC) and radiolabeled with ²¹²Pb, a source of α-particles. In vitro Scatchard assays determined the specific binding of ²¹²Pb-376.96 to adherent differentiated or non-adherent CIC-enriched ES-2 and A2780cp20 ovarian cancer cells. Adherent ovarian cancer cells and non-adherent CIC-enriched tumorspheres treated in vitro with ²¹²Pb-376.96 or the irrelevant isotype-matched ²¹²Pb-F3-C25 were assessed for clonogenic survival. Mice bearing i.p. ES-2 or A2780cp20 xenografts were injected i.p. with 0.17-0.70MBq ²¹²Pb-376.96 or ²¹²Pb-F3-C25 and were used for in vivo imaging, ex vivo biodistribution, and therapeutic survival studies.

RESULTS

²¹²Pb-376.96 was obtained in high yield and purity (>98%); K_d values ranged from 10.6-26.6nM for ovarian cancer cells, with 10⁴-10⁵ binding sites/cell. ²¹²Pb-376.96 inhibited the clonogenic survival of ovarian cancer cells up to 40 times more effectively than isotype-matched control ²¹²Pb-F3-C25; combining ²¹²Pb-376.96 with carboplatin significantly decreased clonogenic survival compared to either agent alone. In vivo imaging and biodistribution analysis 24h after i.p. injection of ²¹²Pb-376.96 showed high peritoneal retention and tumor tissue accumulation (28.7% ID/g in ES-2 ascites, 73.1% ID/g in A2780cp20 tumors); normal tissues showed lower and comparable uptake for ²¹²Pb-376.96 and ²¹²Pb-F3-C25. Tumor-bearing mice treated with ²¹²Pb-376.96 alone or combined with carboplatin survived 2-3 times longer than mice treated with ²¹²Pb-F3-C25 or non-treated controls.

CONCLUSION

These results support additional RIT studies with ²¹²Pb-376.96 for future evaluation in patients with ovarian cancer.

Extracellular vesicles in ovarian cancer: applications to tumor biology, immunotherapy and biomarker discovery

In recent years there has been tremendous interest in both the basic biology and applications of extracellular vesicles (EVs) in translational cancer research. This includes a better understanding of their biogenesis and mechanisms of selective cargo packaging, their precise roles in horizontal communication, and their application as non-invasive biomarkers. The rapid advances in next-generation omics technologies are the driving forces for these discoveries. In this review, the authors focus on recent results of EV research in ovarian cancer. A deeper understanding of ovarian cancer-derived EVs, the types of cargo molecules and their biological roles in cancer growth, metastases and drug resistance, could have significant impact on the discovery of novel biomarkers and innovative therapeutics. Insights into the role of EVs in immune regulation could lead to novel approaches built on EV-based immunotherapy.

Up-Regulation of miR-204 Enhances Anoikis Sensitivity in Epithelial Ovarian Cancer Cell Line Via Brain-Derived Neurotrophic Factor Pathway In Vitro

OBJECTIVE

Genomic loci encoding miR-204, which was predicted to target brain-derived neurotrophic factor (BDNF), were frequently lost in multiple cancer, including epithelial ovarian cancer (EOC). In this study, we aimed to find out the influence of miR-204 expression level on EOC cell anoikis sensitivity and to explore possible mechanisms of this process.

METHODS

First, we screened EOC cells, which maintain anoikis resistance forming an anoikis pattern. miR-204 expression level and apoptosis were measured, respectively, by quantitative reverse transcriptase polymerase chain reaction and Annexin-V-R-PE/7-amino-actinomycin assay. Then we restored the expression level of miR-204 by transfection with pre-miR-204. miR-204 expression level and apoptosis were measured as before; cell invasion and migration ability were detected by transwell invasion assay and wound-healing assay. The messenger RNA level of BDNF was also detected by quantitative reverse transcriptase polymerase chain reaction; Western blot analysis was performed to assess pAKT expression.

RESULTS

Expression of miR-204 is significantly down-regulated in an anoikis pattern. Restored expression level of miR-204 enables cells to acquire more sensitivity to anoikis and decrease invasive and metastatic behavior, and also results in BDNF down-expression and inhibits activation of mitochondria-dependent pathway through the PI3K/AKT signaling pathway leading to cancer cell anoikis in EOC cells.

CONCLUSIONS

miR-204 up-regulation may be linked directly to the sensitivity of EOC cell anoikis by contributing to BDNF down-regulation. Our findings provide a novel mechanism for manipulating miR-204 levels therapeutically to restore anoikis sensitivity.

Role of cystathionine beta synthase in lipid metabolism in ovarian cancer

Elevated lipid metabolism is implicated in poor survival in ovarian cancer (OC) and other cancers; however, current lipogenesis-targeting strategies lack cancer cell specificity. Here, we identify a novel role of cystathionine beta-synthase (CBS), a sulphur amino acid metabolizing enzyme highly expressed in several ovarian cancer cell lines, in driving deregulated lipid metabolism in OC. We examined the role of CBS in regulation of triglycerides, cholesterol and lipogenic enzymes via the lipogenic transcription factors SREBP1 and SREBP2. CBS silencing attenuated the expression of number of key enzymes involved in lipid synthesis (FASN and ACC1). Additionally CBS abrogates lipid uptake in OC cells. Gene silencing of CBS or SREBPs abrogated cellular migration and invasion in OC, while ectopic expression of SREBPs can rescue phenotypic effects of CBS silencing by restoring cell migration and invasion. Mechanistically, CBS represses SREBP1 and SREBP2 at the transcription levels by modulating the transcription factor Sp1. We further established the roles of both CBS and SREBPs in regulating ovarian tumor growth in vivo. In orthotopic tumor models, CBS or SREBP silencing resulted in reduced tumor cells proliferation, blood vessels formation and lipid content. Hence, cancer-selective disruption of the lipid metabolism pathway is possible by targeting CBS and, at least for OC, promises a profound benefit.

An apoptosis-enhancing drug overcomes platinum resistance in a tumour-initiating subpopulation of ovarian cancer

High-grade serous ovarian cancers (HGSCs) are deadly malignancies that relapse despite carboplatin chemotherapy. Here we show that 16 independent primary HGSC samples contain a CA125-negative population enriched for carboplatin-resistant cancer initiating cells. Transcriptome analysis reveals upregulation of homologous recombination DNA repair and anti-apoptotic signals in this population. While treatment with carboplatin enriches for CA125-negative cells, co-treatment with carboplatin and birinapant eliminates these cells in HGSCs expressing high levels of the inhibitor of apoptosis protein cIAP in the CA125-negative population. Birinapant sensitizes CA125-negative cells to carboplatin by mediating degradation of cIAP causing cleavage of caspase 8 and restoration of apoptosis. This co-therapy significantly improves disease-free survival in vivo compared with either therapy alone in tumour-bearing mice. These findings suggest that therapeutic strategies that target CA125-negative cells may be useful in the treatment of HGSC.

Despite normalization of the CA125 serum biomarker at the completion of carboplatin therapy the vast majority of patients with high grade serous ovarian cancers relapse. Here, Janzen et al., identify a sub-population of tumor cells that are CA125 negative, cancer initiating and platinum resistant but readily eliminated with the addition of apoptosis enhancing drugs to carboplatin.

Notch signaling in serous ovarian cancer

Ovarian cancer is the most lethal of all gynecologic malignancies because women commonly present with advanced stage disease and develop chemotherapy refractory tumors. While cytoreductive surgery followed by platinum based chemotherapy are initially effective, ovarian tumors have a high propensity to recur highlighting the distinct need for novel therapeutics to improve outcomes for affected women. The Notch signaling pathway plays an established role in embryologic development and deregulation of this signaling cascade has been linked to many cancers. Recent genomic profiling of serous ovarian carcinoma revealed that Notch pathway alterations are among the most prevalent detected genomic changes. A growing body of scientific literature has confirmed heightened Notch signaling activity in ovarian carcinoma, and has utilized in vitro and in vivo models to suggest that targeting this pathway with gamma secretase inhibitors (GSIs) leads to anti-tumor effects. While it is currently unknown if Notch pathway inhibition can offer clinical benefit to women with ovarian cancer, several GSIs are currently in phase I and II trials across many disease sites including ovary. This review will provide background on Notch pathway function and will focus on the pre-clinical literature that links altered Notch signaling to ovarian cancer progression.

Treatment options in recurrent ovarian cancer: latest evidence and clinical potential

Ovarian cancer (OC) is the fifth most common cause of cancer death in women. Although significant progress has been made in the treatment of OC, the majority of patients experience disease recurrence and receive second-line and sometimes several lines of treatment. Here we review the options available for the treatment of recurrent disease and discuss how different agents are selected, combined and offered in a rationale sequence in the context of multidisciplinary care. We reviewed published work between 1990 and 2013 and meeting abstracts related to the use of chemotherapy and surgery in patients with recurrent ovarian cancer. We discuss treatment regimens, efficacy endpoints and safety profiles of the different therapies. Platinum-based drugs are the most active agents and are selected on the basis of a probability of response to retreatment. Nonplatinum-based chemotherapy regimens are usually given in the 'platinum-resistant' setting and have a modest effect on outcome. Molecular targeted therapy of ovarian cancer given alone or integrated with chemotherapy is showing promising results. Many patients are now receiving more than one line of therapy for recurrent disease, usually platinum based until platinum resistance emerges. The sequential use of chemotherapy regimens and the incorporation of molecularly targeted treatments, either alone or in combination with chemotherapy, have over the last decade significantly extended the median survival of patients with ovarian cancer.

Inhibition of notch signaling in combination with Paclitaxel reduces platinum-resistant ovarian tumor growth

Introduction: Ovarian cancer (OvCa) is the most lethal gynecologic malignancy in the United States because of chemoresistant recurrent disease. Our objective was to investigate the efficacy of inhibiting the Notch pathway with a γ-secretase inhibitor (GSI) in an OvCa patient-derived xenograft model as a single agent therapy and in combination with standard chemotherapy.

Methods: Immunocompromised mice bearing xenografts derived from clinically platinum-sensitive human ovarian serous carcinomas were treated with vehicle, GSI (MRK-003) alone, paclitaxel and carboplatin (P/C) alone, or the combination of GSI and P/C. Mice bearing platinum-resistant xenografts were given GSI with or without paclitaxel. Gene transcript levels of the Notch pathway target Hes1 were analyzed using RT-PCR. Notch1 and Notch3 protein levels were evaluated. The Wilcoxon rank-sum test was used to assess significance between the different treatment groups.

Results: Expression of Notch1 and 3 was variable. GSI alone decreased tumor growth in two of three platinum-sensitive ovarian tumors (p < 0.05), as well as in one of three platinum-sensitive tumors (p = 0.04). The combination of GSI and paclitaxel was significantly more effective than GSI alone and paclitaxel alone in all platinum-resistant ovarian tumors (all p < 0.05). The addition of GSI did not alter the effect of P/C in platinum-sensitive tumors. Interestingly, although the response of each tumor to chronic GSI exposure did not correlate with its endogenous level of Notch expression, GSI did negatively affect Notch signaling in an acute setting.

Conclusion: Inhibiting the Notch signaling cascade with a GSI reduces primary human xenograft growth in vivo. GSI synergized with conventional cytotoxic chemotherapy only in the platinum-resistant OvCa models with single agent paclitaxel. These findings suggest inhibition of the Notch pathway in concert with taxane therapy may hold promise for treatment of platinum-resistant OvCa.

Loss of HSulf-1 expression enhances tumorigenicity by inhibiting Bim expression in ovarian cancer

The expression of human Sulfatase1 (HSulf-1) is downregulated in the majority of primary ovarian cancer tumors, but the functional consequence of this downregulation remains unclear. Using two different shRNAs (Sh1 and Sh2), HSulf-1 expression was stably downregulated in ovarian cancer OV202 cells. We found that HSulf-1-deficient OV202 Sh1 and Sh2 cells formed colonies in soft agar. In contrast, nontargeting control (NTC) shRNA-transduced OV202 cells did not form any colonies. Moreover, subcutaneous injection of OV202 HSulf-1-deficient cells resulted in tumor formation in nude mice, whereas OV202 NTC cells did not. Also, ectopic expression of HSulf-1 in ovarian cancer SKOV3 cells significantly suppressed tumor growth in nude mice. Here, we show that HSulf-1-deficient OV202 cells have markedly decreased expression of proapoptotic Bim protein, which can be rescued by restoring HSulf-1 expression in OV202 Sh1 cells. Enhanced expression of HSulf-1 in HSulf-1-deficient SKOV3 cells resulted in increased Bim expression. Decreased Bim levels after loss of HSulf-1 were due to increased p-ERK, because inhibition of ERK activity with PD98059 resulted in increased Bim expression. However, treatment with a PI3 kinase/AKT inhibitor, LY294002, failed to show any change in Bim protein level. Importantly, rescuing Bim expression in HSulf-1 knockdown cells significantly retarded tumor growth in nude mice. Collectively, these results suggest that loss of HSulf-1 expression promotes tumorigenicity in ovarian cancer through regulating Bim expression.

Synergistic enhancement of cancer therapy using a combination of ceramide and docetaxel

Ceramide (CE)-based combination therapy (CE combination) as a novel therapeutic strategy has attracted great attention in the field of anti-cancer therapy. The principal purposes of this study were to investigate the synergistic effect of CE in combination with docetaxel (DTX) (CE + DTX) and to explore the synergy mechanisms of CE + DTX. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and combination index (CI) assay showed that simultaneous administration of CE and DTX with a molar ratio of 0.5:1 could generate the optimal synergistic effect on murine malignant melanoma cell (B16, CI = 0.31) and human breast carcinoma cell (MCF-7, CI = 0.48). The apoptosis, cell cycle, and cytoskeleton destruction study demonstrated that CE could target and destruct the microfilament actin, subsequently activate Caspase-3 and induce apoptosis. Meanwhile, DTX could target and disrupt the microtubules cytoskeleton, leading to a high proportion of cancer cells in G2/M-phase arrest. Moreover, CE plus DTX could cause a synergistic destruction of cytoskeleton, which resulted in a significantly higher apoptosis and a significantly higher arrest in G2/M arrest comparing with either agent alone (p < 0.01). The in vivo antitumor study evaluated in B16 tumor-bearing mice also validated the synergistic effects. All these results suggested that CE could enhance the antitumor activity of DTX in a synergistic manner, which suggest promising application prospects of CE + DTX combination treatment.

Ovarian cancer: risk factors, treatment and management

Ovarian cancer is the fifth most common cancer affecting women in the UK today, with associated statistics illustrating a steadily increasing rate, particularly in women aged 65 and over (Cancer Research UK, 2013). There are no recognised preventative measures and no effective screening tool. Although evidence suggests that the majority of women experience a variety of non-specific symptoms in the year before diagnosis, the disease it is not commonly recognised until an advanced stage, leading to increased mortality and morbidity. This highlights the need to raise awareness among health professionals and women as a whole, as early recognition undoubtedly improves ovarian cancer survival. Best clinical practice in the UK for the recognition and initial management of ovarian cancer is provided by the National Institute for Health and Care Excellence (NICE). Clinical guideline CG 122 (NICE, 2011) and quality standard QS 18 (NICE, 2012) use relevant clinical evidence to define high-quality care standards for ovarian cancer management. Accurate staging of ovarian cancer is essential to the provision of individualised care and management. However, there is currently no single test that provides a reliable indicator of ovarian malignancy. At present, risk-of-malignancy scores are calculated by serum cancer antigen 125 (CA 125) levels, ultrasound score and menopausal status. These are widely used to identify women who are at high risk and require referral to a specialised gynaecological oncology service. Women diagnosed with ovarian cancer require information and support. The clinical nurse specialist acts as a key worker, providing communication, support and holistic care throughout a woman's cancer journey. The value of this role cannot be underestimated. Surgery followed by platinum-based chemotherapy is the usual standard treatment pathway, although individualised assessment and management may deviate from it. Early disease may be successfully treated with surgery alone; advanced disease may require complex management and treatment. New treatments such as bevacizumab show promise of improving ovarian cancer outcomes.

MiR-106a targets Mcl-1 to suppress cisplatin resistance of ovarian cancer A2780 cells

Resistance to chemotherapy is a major obstacle for the effective treatment of advanced ovarian cancer. The mechanism of chemoresistance is still poorly understood. Recently, more and more evidence showed microRNAs (miRNAs) modulated many key molecules and pathways involved in chemotherapy. microRNA-106a (miR-106a) has been implicated in many cancers, but its role in ovarian cancer and drug resistance still remains unexplored. This study was to investigate whether miR-106a mediated resistance of the ovarian cancer cell line A2780 to the chemotherapeutic agent cisplatin (DDP). The different levels of miR-106a in A2780 cells and their resistant variant A2780/DDP cells were identified by using real-time PCR. MTT assay and flow cytometry were used to analyze the effect of miR-106a on cisplatin resistance of these paired cells. Real-time PCR, Western blotting and luciferase reporter assay were applied to explore whether Mcl-1 was a target of miR-106a. As compared to A2780 cells, the expression of miR-106a was down-regulated in the cisplatin resistant cell line A2780/DDP. Moreover, knockdown of miR-106a dramatically decreased antiproliferative effects and apoptosis induced by cisplatin in A2780 cells, while overexpression of miR-106a significantly increased antiproliferative effects and apoptosis induced by cisplatin in A2780/DDP cells. Furthermore, miR-106a inhibited cell survival and cisplatin resistance through downregulating the expression of Mcl-1. Mcl-1 was a direct target of miR-106a. These results suggest that miR-106a may provide a novel mechanism for understanding cisplatin resistance in ovarian cancer by modulating Mcl-1.