Parental Ovarian Cancer Cell Research Articles

Analysis of miRNAs miR-125a-5p, -27a-5p, -193a-5p, -135b-5p, -451a, -495-3p and -136-5p in parental ovarian cancer cells and secreted extracellular vesicles

Introduction. The identification of markers for liquid diagnostics of ovarian cancer is one of the most urgent tasks of gynecologic oncology. Currently, extracellular vesicles (EVs) are of great interest as a source of oncomarkers, including miRNA markers. We have previously shown that the levels of miR-125a-5p, -27a-5p, -193a-5p and 135b-5p are significantly elevated and miR-451a, -495-3p and -136-5p are significantly decreased in the EVs from uterine aspirates of ovarian cancer patients.Aim. Analysis of miR-125a-5p, -27a-5p, -193a-5p, 135b-5p, 451a, 495-3p and -136-5p levels in ovarian cancer cell cultures and secreted EVs.Material and methods. Cultivation of ovarian cancer cell lines: OVCAR-3, OVCAR-4, OVCAR-8 and SKOV3; EVs isolation from conditioned medium by ultracentrifugation; EVs validation by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), western blot analysis of exosomal markers; isolation of miRNAs from cells and EVs; analysis of miRNAs by Stem-Loop – reverse transcription-quantitative polymerase chain reaction.Results. In all cell lines studied, the expression of miR-125a-5p, -27a-5p, -193a-5p and -135b-5p significantly exceeds the expression of -451a, -495-3p and -136-5p. All ovarian cancer cell lines are featured by a “cells >EVs” ratio for highly expressed miRNAs and “EVs >cells” ratio for poorly expressed miRNAs.Conclusion. The results of the study support the relation between the differential expression of studied miRNAs and the pathogenesis of ovarian cancer and confirm the high diagnostic potential of these molecules.

Abstract B007: NAD+ metabolism drives PARPi resistance in ovarian cancer cells

Abstract NAD+ is a coenzyme for redox reactions and a cofactor for enzymes such as PARPs and Sirtuins. The nuclear enzyme PARP1 is a major consumer of NAD+, which is cleaved during the catalytic activation of PARP1 in response to DNA damage. PARP1 inhibitors compete with NAD+ for the catalytic site of PARP1 and reduce the catalytic activity of PARP1 and impair DNA damage repair. Recently PARP inhibitors (PARPi) have shown efficacy in the treatment of ovarian cancers and most patients with defects in homologous repair of DNA damage are now on PARPi maintenance. But, heterogeneous responses to PARPi is limiting their clinical efficacy. To identify the mechanisms of PARPi resistance, we generated a panel of ovarian cancer cells with acquired resistance to niraparib (PARPiR), an FDA approved PARP inhibitor. We demonstrated that the PARPiR cells are also resistant to other FDA approved PARP inhibitors rucaparib and olaparib. This data suggested that a common mechanism of resistance underlies poor response to the FDA approved PARP inhibitors. Since PARP1 activity is tightly controlled by the cellular NAD+ levels, we next investigated the role of NAD+ biosynthesis in PARPi resistance. Metabolomic profiling of the parental and PARPiR cells demonstrated that PARPiR cells have elevated levels of NAD+ metabolism. Indeed, treating the PARPiR cells with inhibitors of NAD+ synthesis restored the sensitivity to PARP inhibitors. Moreover, culturing the previously sensitive parental ovarian cancer cells in NAD+ precursors decreased their sensitivity to PARP inhibitors. These data collectively demonstrated that high levels of NAD+ metabolism causes PARP inhibitor resistance in ovarian cancer cells. Complementary to the metabolomic analysis, results from phenotypic assays in PARPiR cells revealed that high levels of NAD+ maintain cellular quiescence in PARPiR cells. In summary, our results demonstrated that high levels of NAD+ biosynthesis causes PARPi resistance by maintaining cellular quiescence. There is an urgent need to identify the mechanisms of resistance to PARP inhibitors to increase their clinical efficacy. Our study identified that maintenance of quiescence is a fundamental mechanism of PARPi resistance. We also demonstrated that inhibiting NAD+ biosynthesis reverses PARP inhibitor resistance. Citation Format: Subin Myong, Hardik Shah, Benedikt Nagele, Reshma Rajesh, Sridevi Challa. NAD+ metabolism drives PARPi resistance in ovarian cancer cells [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B007.

Understanding of Ovarian Cancer Cell-Derived Exosome Tropism for Future Therapeutic Applications.

Exosomes, a subtype of extracellular vesicles, ranging from 50 to 200 nm in diameter, and mediate cell-to-cell communication in normal biological and pathological processes. Exosomes derived from tumors have multiple functions in cancer progression, resistance, and metastasis through cancer exosome-derived tropism. However, there is no quantitative information on cancer exosome-derived tropism. Such data would be highly beneficial to guide cancer therapy by inhibiting exosome release and/or uptake. Using two fluorescent protein (mKate2) transfected ovarian cancer cell lines (OVCA4 and OVCA8), cancer exosome tropism was quantified by measuring the released exosome from ovarian cancer cells and determining the uptake of exosomes into parental ovarian cancer cells, 3D spheroids, and tumors in tumor-bearing mice. The OVCA4 cells release 50 to 200 exosomes per cell, and the OVCA8 cells do 300 to 560 per cell. The uptake of exosomes by parental ovarian cancer cells is many-fold higher than by non-parental cells. In tumor-bearing mice, most exosomes are homing to the parent cancer rather than other tissues. We successfully quantified exosome release and uptake by the parent cancer cells, further proving the tropism of cancer cell-derived exosomes. The results implied that cancer exosome tropism could provide useful information for future cancer therapeutic applications.

Abstract 6244: Design, synthesis, and structure-activity relationships of substituted pyrido[3,2-d]pyrimidines as microtubule targeting agents and anti-cancer agents

Abstract Microtubules (MTs) are composed of αβ-tubulin heterodimers and are essential components of the cellular cytoskeleton involved in critical cellular functions, including mitosis, cell migration and signaling, intracellular trafficking, and angiogenesis. Microtubule targeting agents (MTAs) are highly successful chemotherapeutic agents because they target MT dynamics and interfere with MT-dependent cellular processes. The clinical efficacy of MTAs is limited by multidrug resistance due to expression of the P-glycoprotein (Pgp) drug efflux pump or increased expression of βIII-tubulin. This necessitates the development of novel MTAs effective against cell lines expressing these forms of drug resistance, which could offer potential advantages in patients who fail to respond to current MTAs, such as paclitaxel. Previously, we reported colchicine site (CS) binding compound 1 with a pyrido[3,2-d]pyrimidine scaffold and a 2-H substitution and N4-4’-methoxyaniline substitution inhibited colchicine binding and tubulin assembly (87% inhibition at 5 µM and IC50 = 1.3 µM, respectively). Compounds 2-9 were designed with a 2-CH3 substitution to evaluate the structure-activity relationships at the 4-position by using conformational restriction and isosteric replacements. Compounds 2-9 were synthesized, and the biological evaluation showed that compounds 2-9 inhibited tubulin assembly (7, IC50 = 0.72 μM) and binding of colchicine to tubulin (7, 97% inhibition at 5 µM, 81% at 0.5 µM). Compound 7 was found to be highly potent in the MCF-7 breast cancer cell line with an IC50 of 2.5 nM which was ~3.5-fold better than combretastatin-A4 (CA4). Compound 7 inhibited the growth of the human ovarian cancer cell line OVCAR-8 with an IC50 = 3.0 nM. For the Pgp overexpressing cell line NCI/ADR-RES, 7 was equally potent (IC50 = 3.0 nM), whereas paclitaxel was almost inactive (IC50 = 1,500 nM). Thus, we have identified 2-CH3 substituted pyrido[3,2-d]pyrimidines as a novel structural scaffold for inhibition of tubulin assembly and colchicine binding that have potent cytotoxic activity against the breast cancer cell line MCF-7 and against both the parental ovarian cancer cell line OVCAR-8 and its derivative Pgp overexpressing cell line NCI/ADR-RES. These compounds thus merit further study as potential cancer chemotherapeutic agents. Citation Format: Yesha Vijaykumar Shah, Ruoli Bai, Ernest Hamel, Aleem Gangjee. Design, synthesis, and structure-activity relationships of substituted pyrido[3,2-d]pyrimidines as microtubule targeting agents and anti-cancer agents. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6244.

High co‐expression of SLC7A11 and GPX4 as a predictor of platinum resistance and poor prognosis in patients with epithelial ovarian cancer

The aim was to assess the expression levels of SLC7A11 and GPX4 in relation to platinum resistance and prognosis in patients with epithelial ovarian cancer (EOC). A retrospective cohort study. Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China. We included 192 eligible patients from hospital between January 2002 and December 2018. We retrospectively analysed the medical records of patients with EOC. Surgical specimens of EOC were stained for SLC7A11 and GPX4. Survival analysis was performed using the Kaplan-Meier and Cox regression methods. Clinical end points include platinum-free interval (PFI), progression-free survival (PFS) and overall survival (OS). Patients with high co-expression levels of SLC7A11 and GPX4 had a 60-fold higher risk of platinum resistance compared with those with low co-expression (risk ratio, 60.46; 95% confidence interval [CI] 22.76-160.58; p < 0.001). Moreover, high co-expression level of SLC7A11 and GPX4 was an independent prognostic factor for poor OS (p < 0.001, hazard ratio [HR]4.44, 95% CI, 2.77-7.14) and poor PFS (p < 0.001, HR=5.73, 95% CI, 3.86-8.73). For in vitro experiments, SLC7A11 and GPX4 expression were both upregulated in platinum-resistant cells compared with their parental ovarian cancer cells, and siRNA-induced SLC7A11 and GPX4 inhibition decreased platinum resistance. High expression levels of SLC7A11 and GPX4 are associated with platinum resistance in EOC patients. High co-expression of SLC7A11 and GPX4 may be a significant independent prognostic factor and a potential therapeutic target for platinum resistance in EOC patients.

In vivo selection reveals autophagy promotes adaptation of metastatic ovarian cancer cells to abdominal microenvironment.

Peritoneal dissemination is the most frequent metastatic route of ovarian cancer. However, due to the high heterogeneity in ovarian cancer, most conventional studies lack parental tumor controls relevant to metastases and, thus, it is difficult to trace the molecular changes of cancer cells along with the selection by the abdominal microenvironment. Here, we established an in vivo mouse peritoneal dissemination scheme that allowed us to select more aggressive sublines from parental ovarian cancer cells, including A2780 and SKOV‐3. Microarray and gene profiling analyses indicated that autophagy‐related genes were enriched in selected malignant sublines. Detection of LC3‐II, p62 and autophagic puncta demonstrated that these malignant variants were more sensitive to autophagic induction when exposed to diverse stress conditions, such as high cell density, starvation and drug treatment. As compared with parental A2780, the selected variant acquired the ability to grow better under high‐density stress; however, this effect was reversed by addition of autophagic inhibitors or knockdown of ATG5. When analyzing the clinical profiles of autophagy‐related genes identified to be enriched in malignant A2780 variant, 73% of them had prognostic significance for the survival of ovarian cancer patients. Taken together, our findings indicate that an increase in autophagic potency among ovarian cancer cells is crucial for selection of metastatic colonies in the abdominal microenvironment. In addition, the derived autophagic gene profile can not only predict prognosis well but can also be potentially applied to precision medicine for identifying those ovarian cancer patients suitable for taking anti–autophagy cancer drugs.

Long-term fluorescence hyperspectral imaging of on-chip treated co-culture tumour spheroids to follow clonal evolution.

Multicellular tumour spheroids are an ideal in vitro tumour model to study clonal heterogeneity and drug resistance in cancer research because different cell types can be mixed at will. However, measuring the individual response of each cell population over time is challenging: current methods are either destructive, such as flow cytometry, or cannot image throughout a spheroid, such as confocal microscopy. Our group previously developed a wide-field fluorescence hyperspectral imaging system to study spheroids formed and cultured in microfluidic chips. In the present study, two subclones of a single parental ovarian cancer cell line transfected to express different fluorophores were produced and co-culture spheroids were formed on-chip using ratios forming highly asymmetric subpopulations. We performed a 3D proliferation assay on each cell population forming the spheroids that matched the 2D growth behaviour. Response assays to PARP inhibitors and platinum-based drugs were also performed to follow the clonal evolution of mixed populations. Our experiments show that hyperspectral imaging can detect spheroid response before observing a decrease in spheroid diameter. Hyperspectral imaging and microfluidic-based spheroid assays provide a versatile solution to study clonal heterogeneity, able to measure response in subpopulations presenting as little as 10% of the initial spheroid.

Restoration of microRNA-708 sensitizes ovarian cancer cells to cisplatin via IGF2BP1/Akt pathway.

A previous study has shown that microRNA-708 (miR-708) functions as a metastasis suppressor in ovarian cancer. In this study, we aimed to explore its implication in regulating cisplatin sensitivity in ovarian cancer cells. To this end, ovarian cancer cells were transfected with miR-708-expressing plasmids or vector before treatment with different concentrations of cisplatin for 48 h. The 50% inhibitory concentration (IC50 ) value was calculated. Apoptosis was analyzed by measuring caspase-3 activity. The target gene mediating the function of miR-708 was identified. Ectopic expression of miR-708 sensitized SKOV3 and A2780 cells to cisplatin, decreasing the IC50 value by two- to threefold. miR-708 overexpression significantly augmented cisplatin-induced apoptosis in ovarian cancer cells, which was coupled with increased caspase-3 activity by two- to fourfold. Similarly, overexpression of miR-708 increased the sensitivity of cisplatin-resistant SKOV3/DDP and A2780/DDP cells to cisplatin-induced toxicity, reducing the IC50 by three- and fivefold, respectively. Delivery of miR-708 enhanced cisplatin-induced elevation in caspase-3 activity in both cisplatin-resistant and parental ovarian cancer cells. Mechanistically, miR-708 downregulated the expression of insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) and suppressed Akt phosphorylation. Silencing of IGF2BP1 markedly blocked the phosphorylation of Akt. Overexpression of IGF2BP1 restored cisplatin resistance and Akt phosphorylation in miR-708-overexpressing ovarian cancer cells. Collectively, miR-708 increases the susceptibility of ovarian cancer cells to cisplatin by targeting IGF2BP1 and inhibiting Akt signaling. Delivery of miR-708 may represent a promising strategy for improving cisplatin chemotherapy.

Heparanase is involved in proliferation and invasion of ovarian cancer cells.

Heparanase(HPSE), an endo-β -D-glucuronidase, is found overexpressed in Ovarian cancer (OC). The purpose of our work was to investigate primitively the possible role of HPSE in the development of OC. In this study, RNA interference (RNAi) with a HPSE small hairpin RNAs(HPSE-shRNA) and plasmid with HPSE were used to identify the effects of HPSE on the regulation of malignant behaviors of OC. OV-90 and SKOV3 were selected as a cell model in vitro and in vivo. The results showed that down-regulation of HPSE can significantly inhibit the proliferative and invasive ability of SKOV3 cells, and up-regulation of HPSE in OV-90 cells showed the opposite effects. Compared with the parental OC cells, HPSE silencing cells exhibited attenuated capacities in developing tumor in nude mice, while the growth tumors xenografts derived from these cells were dramatically regressed. In conclusion, our results suggest that HPSE contributes to the proliferation and metastasis of OC and HPSE might be a potent molecular target for OC treatment.

Cathepsin L is involved in proliferation and invasion of ovarian cancer cells.

Cathepsin L (CTSL) is a lysosomal cysteine protease that has been found to be overexpressed in ovarian cancer (OC). The aim of the present study was to investigate the possible involvement of CTSL in the development of OC. In this study, RNA interference with a CTSL small hairpin RNA (CTSL-shRNA), and a plasmid carrying CTSL were used to identify the effects of this enzyme on the regulation of the malignant behavior of OC cells. OV-90 and SKOV3 human ovarian cancer cell lines were selected as cell models in vitro and in vivo. The results showed that downregulation of CTSL significantly inhibits the proliferative and invasive capability of SKOV3 cells, and that upregulation of CTSL in OV-90 cells leads to opposite effects. Compared with parental OC cells, cells in which CTSL was silenced exhibited a reduced capacity to develop into tumors in nude mice, while the growth of tumor xenografts derived from these cells was markedly constrained. In conclusion, the results suggested that CTSL contributes to the proliferation and metastasis of OC, and that CTSL may be a novel molecular target for OC treatment.

Abstract 3377: Glutamine mediated aggressiveness and drug sensitivity in ovarian cancer cells

Abstract Platinum-based drugs such as cisplatin, carboplatin and xoaliplatin hav been introduced into clinical trials and their outcomes has progressed the treatment on several tumors, including ovarian cancer. However, cancer cells acquire chemo-resistance in the long term incubation of drugs, which turns out to be the major limitation for cancer therapy. Recent studies have shown that cisplatin can accumulate in mitochondria and induce cytochrome C release, thereby resulting in apoptosis. We found that glutamine plays a vital role in maintaining mitochondrial integrity and function by regulating NAD+ and NADH. Using bioenergetics and isotopomer analysis we show that chemodrugs in presence of glutamine affect oxidative phosphorylation in drug sensitive parental ovarian cancer cells. Addition of NAD+ substrates increased NAD/NADH ratio abrogating cisplatin's effect on cell death and mitochondrial dysfunction. Furthermore, drug resistant cancer cells had relatively higher glutamine dependence when compared with parental cells. Importantly, we found that when glutamine's entry into TCA cycle was inhibited ovarian cancer cells became more sensitive to chemotherapy. Our findings are based on the quantification of metabolites, related to glycolysis, the pentose phosphate pathway, the TCA and urea cycles, and amino acids and nucleotide metabolism, and comparison of these pathways fluxes in drug sensitive and drug resistant ovarian cancer. The insights obtained present a unique opportunity for overcoming the drug resistance limitation in clinical trials in ovarian cancers. Citation Format: Lifeng Yang, Tyler J. Moss, Juan C. Marini, Selanere Mangala, Stephen Wahlig, Julia Win, Dan Su, Anil K. Sood, Prahlad T. Ram, Deepak Nagrath. Glutamine mediated aggressiveness and drug sensitivity in ovarian cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3377. doi:10.1158/1538-7445.AM2014-3377

Abstract 539: Downregulation of hnRNP A1 by miRNAs as a new mechanism of survival in ovarian cancer

Abstract Background. Posttranscriptional regulation is a critical control point for the expression of genes that promote or retard tumor growth. The mRNA-binding protein hnRNP A1 is required for the processing of miR-18a, an inhibitor of k-ras expression. In this study we hypothesized that downmodulation of hnRNP A1 by miR-25 and miR-15a controls the expression of miR-18a and k-ras by modulating nuclear and cytoplasmic miRNA processing at the posttranscriptional level. Methods. In this study, we determined the expression of hnRNP A1 at mRNA and protein levels in three parental ovarian cancer cells lines (Skov3ip1, HeyA8, and A2780) and their chemotherapy-resistant derivatives (Skov3-TR, HeyA8 MDR, and A2780 cp20). We also predicted in silico which miRNAS can target hnRNP A1 and confirmed the miRNA expression by real-time PCR. Moreover, we inhibited miR-25 and mir-15a to determine their tumorigenic potential in vitro. We also correlated the expression of miR-25 and miR-15a and/or miR-18a and k-ras expression in the TCGA data. Results. Downregulation of hnRNP A1 at the RNA and protein levels was observed in the taxane-resistant cell lines but not in the cisplatin-resistant cell line. Furthermore, we predicted in silico that miR-25and miR-15a can target hnRNP A1 and confirmed the overexpression of these microRNAs in SKOV3-TR (5- and 3-fold, respectively) and HeyA8 MDR (3-fold) by real-time PCR. We also analyzed overall survival, trying to find a correlation between k-ras and miR-15a (high 23.77, low 33.97 months), k-ras and miR-25 (high 16.95, low 35.21 months), and the combination of k-ras, miR-25, and miR18a (k-ras high, miR25 high, mir18a low, 20.73 months; k-ras low, miR25 low, mir18a high, 31.49 months). Comparison of these data with a validation set yielded similar results. Conclusion. These results underscore the importance of a previously uncharacterized circuit of posttranscriptional regulation between miR-25 or -15a and RNA-binding protein hnRNP A1 that regulates miR-18a and k-ras expression. This circuit represents a unique opportunity for novel therapeutics approaches. Citation Format: Cristian Rodriguez-Aguayo, Paloma Monroig, Maria I. Almeida, Cristina Ivan, Vianey Gonzalez-Villasana, Maitri Y. Shah, Anil K. Sood, George Calin, Gabriel Lopez-Berestein. Downregulation of hnRNP A1 by miRNAs as a new mechanism of survival in ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 539. doi:10.1158/1538-7445.AM2014-539

An Antimitotic and Antivascular Agent BPR0L075 Overcomes Multidrug Resistance and Induces Mitotic Catastrophe in Paclitaxel-Resistant Ovarian Cancer Cells

Paclitaxel plays a major role in the treatment of ovarian cancer; however, resistance to paclitaxel is frequently observed. Thus, new therapy that can overcome paclitaxel resistance will be of significant clinical importance. We evaluated antiproliferative effects of an antimitotic and antivascular agent BPR0L075 in paclitaxel-resistant ovarian cancer cells. BPR0L075 displays potent and broad-spectrum cytotoxicity at low nanomolar concentrations (IC50 = 2–7 nM) against both parental ovarian cancer cells (OVCAR-3, SKOV-3, and A2780-1A9) and paclitaxel-resistant sublines (OVCAR-3-TR, SKOV-3-TR, 1A9-PTX10), regardless of the expression levels of the multidrug resistance transporter P-gp and class III β-tubulin or mutation of β-tubulin. BPR0L075 blocks cell cycle at the G2/M phase in paclitaxel-resistant cells while equal concentration of paclitaxel treatment was ineffective. BPR0L075 induces cell death by a dual mechanism in parental and paclitaxel-resistant ovarian cancer cells. In the parental cells (OVCAR-3 and SKOV-3), BPR0L075 induced apoptosis, evidenced by poly(ADP-ribose) polymerase (PARP) cleavage and DNA ladder formation. BPR0L075 induced cell death in paclitaxel-resistant ovarian cancer cells (OVCAR-3-TR and SKOV-3-TR) is primarily due to mitotic catastrophe, evidenced by formation of giant, multinucleated cells and absence of PARP cleavage. Immunoblotting analysis shows that BPR0L075 treatment induced up-regulation of cyclin B1, BubR1, MPM-2, and survivin protein levels and Bcl-XL phosphorylation in parental cells; however, in resistant cells, the endogenous expressions of BubR1 and survivin were depleted, BPR0L075 treatment failed to induce MPM-2 expression and phosphorylation of Bcl-XL. BPR0L075 induced cell death in both parental and paclitaxel-resistant ovarian cancer cells proceed through caspase-3 independent mechanisms. In conclusion, BPR0L075 displays potent cytotoxic effects in ovarian cancer cells with a potential to overcome paclitaxel resistance by bypassing efflux transporters and inducing mitotic catastrophe. BPR0L075 represents a novel microtubule therapeutic to overcome multidrug resistance and trigger alternative cell death by mitotic catastrophe in ovarian cancer cells that are apoptosis-resistant.

Abstract 4500: Tubulin binding agent BPR0L075 induces iitotic catastrophe in paclitaxel-resistant ovarian cancer cells that is independent of caspase-3 activation.

Abstract Paclitaxel resistance is a significant clinical problem. In the current study, we evaluated antiproliferative effects of a tubulin binding agent BPR0L075 in paclitaxel-resistant ovarian cancer cells. BPR0L075 displays potent and broad-spectrum cytotoxicity at low nanomolar concentrations (IC50 = 2-7 nM) against both parental ovarian cancer cells (OVCAR-3, SKOV-3, and A2780-1A9) and paclitaxel-resistant sublines (OVCAR-3-TR, SKOV-3-TR, 1A9-PTX10), regardless of the expression levels of the multidrug resistance transporter P-gp and class III β-tubulin or mutation of β-tubulin. BPR0L075 blocks cell cycle at the G2/M phase in paclitaxel-resistant cells while equal concentration of paclitaxel treatment was ineffective. BPR0L075 induced cell death in paclitaxel-resistant ovarian cancer cells (OVCAR-3-TR and SKOV-3-TR) is primarily due to mitotic catastrophe, evidenced by formation of giant, multinucleated cells and absence of PARP cleavage and DNA fragmentation. Immunoblot analysis shows that survivin protein expression was depleted in resistant cells. BPR0L075 induced cell death in the paclitaxel-resistant ovarian cancer cells proceed through caspase-3 independent mechanisms, supported by the absence of caspase-3 cleavage and ineffectiveness of caspase-3 inhibitor in protecting the resistant cells from BPR0L075 induced cell death. In conclusion, BPR0L075 displays potent cytotoxic effects in ovarian cancer cells with a potential to overcome paclitaxel resistance by bypassing efflux transporters and inducing mitotic catastrophe. BPR0L075 represents a promising antimitotic agent in controlling taxane-resistant ovarian cancer cells. Citation Format: Xinli Liu, Weimin Sun, Xiaolei Wang, Erxi Wu. Tubulin binding agent BPR0L075 induces iitotic catastrophe in paclitaxel-resistant ovarian cancer cells that is independent of caspase-3 activation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4500. doi:10.1158/1538-7445.AM2013-4500

Abstract 4799: Identification of drug resistance targets in ovarian cancer using a proteomic approach

Abstract Ovarian cancer ranks first in the number of deaths and second in the number of new cases among gynecological cancers. In the majority of the cases, surgery is the intervention of choice, but chemotherapy has progressed considerably over the last years. First-line treatment for advanced-stage disease is a combination of carboplatin and paclitaxel. However, drug resistance has become a major obstacle to the successful chemotherapeutic treatment of human cancers. Currently, there is no clear consensus on treatment options for ovarian cancer patients who acquired drug resistance, due to the lack of knowledge about drug resistance mechanisms. There is an urgent need to explain how drug resistance occurs and to identify proteins related to this phenomenon, so that inhibitors can be designed. The aims of this study are to develop and optimise a two-dimensional gel electrophoresis method to compare protein profile of human ovarian cancer cell lines, which are sensitive or resistant to anticancer chemotherapy, so that proteins related to drug resistance can be identified using mass spectrometry. The parental ovarian cancer cell line models PEO1 and SKOV-3 are used as drug sensitive reference cell lines. Novel drug resistant models, derived from the parental lines, with in vitro acquired resistance to paclitaxel and carboplatin are used alongside their respective drug sensitive parental counterparts. Proteins related to tumorigenesis or drug resistance, either new or previously reported, were identified in at least one of the three cell lines. These proteins belong to different classes and are responsible for distinct functions within the cell, such as cytoskeleton and cell structure, detoxification and stress response, and cellular metabolism. This is the first proteomic study on these specific ovarian cancer cell lines using paclitaxel and carboplatin. The results obtained will be useful for further studies of resistance mechanisms and screening of resistance biomarkers for the development of tailored therapeutic strategies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4799. doi:1538-7445.AM2012-4799