Multidrug-resistant Ovarian Cancer Research Articles

Co-delivery of Paclitaxel/Atovaquone/Quercetin to regulate energy metabolism to reverse multidrug resistance in ovarian cancer by PLGA-PEG nanoparticles

Ovarian cancer is a malignant tumor that seriously endangers the lives of women, with chemotherapy being the primary clinical treatment. However, chemotherapy encounters the problem of generating multidrug resistance (MDR), mainly due to drug efflux induced by P-glycoprotein (P-gp), which decreases intracellular accumulation of chemotherapeutic drugs. The drugs efflux mediated by P-gp requires adenosine triphosphate (ATP) hydrolysis to provide energy. Therefore, modulating energy metabolism pathways and inhibiting ATP production may be a potential strategy to reverse MDR. Herein, we developed a PTX-ATO-QUE nanoparticle (PAQNPs) based on a PLGA-PEG nanoplatform capable of loading the mitochondrial oxidative phosphorylation (OXPHOS) inhibitor atovaquone (ATO), the glycolysis inhibitor quercetin (QUE), and the chemotherapeutic drug paclitaxel (PTX) to reverse MDR by inhibiting energy metabolism through multiple pathways. Mechanistically, PAQNPs could effectively inhibit the OXPHOS and glycolytic pathways of A2780/Taxol cells by suppressing the activities of mitochondrial complex III and hexokinase II (HK II), respectively, ultimately decreasing intracellular ATP levels in tumor cells. Energy depletion can effectively inhibit cell proliferation and reduce P-gp activity, increasing the chemotherapeutic drug PTX accumulation in the cells. Moreover, intracellular reactive oxygen species (ROS) is increased with PTX accumulation and leads to chemotherapy-resistant cell apoptosis. Furthermore, PAQNPs significantly inhibited tumor growth in the A2780/Taxol tumor-bearing NCG mice model. Immunohistochemical (IHC) analysis of tumor tissues revealed that P-gp expression was suppressed, demonstrating that PAQNPs are effective in reversing MDR in tumors by inducing energy depletion. In addition, the safety study results, including blood biochemical indices, major organ weights, and H&E staining images, showed that PAQNPs have a favorable in vivo safety profile. In summary, the results suggest that the combined inhibition of the two energy pathways, OXPHOS and glycolysis, can enhance chemotherapy efficacy and reverse MDR in ovarian cancer.

Harnessing small extracellular vesicles for pro-oxidant delivery: novel approach for drug-sensitive and resistant cancer therapy

Multidrug resistance (MDR) is an inevitable clinical problem in chemotherapy due to the activation of abundant P-glycoprotein (P-gp) that can efflux drugs. Limitations of current cancer therapy highlight the need for the development of a comprehensive cancer treatment strategy, including drug-resistant cancers. Small extracellular vesicles (sEVs) possess significant potential in surmounting drug resistance as they can effectively evade the efflux mechanism and transport small molecules directly to MDR cancer cells. One mechanism mediating MDR in cancer cells is sustaining increased levels of reactive oxygen species (ROS) and maintenance of the redox balance with antioxidants, including glutathione (GSH). Herein, we developed GSH-depleting benzoyloxy dibenzyl carbonate (B2C)-encapsulated sEVs (BsEVs), which overcome the efflux system to exert highly potent anticancer activity against human MDR ovarian cancer cells (OVCAR-8/MDR) by depleting GSH to induce oxidative stress and, in turn, apoptotic cell death in both OVCAR-8/MDR and OVCAR-8 cancer cells. BsEVs restore drug responsiveness by inhibiting ATP production through the oxidation of nicotinamide adenine dinucleotide with hydrogen (NADH) and inducing mitochondrial dysfunction, leading to the dysfunction of efflux pumps responsible for drug resistance. In vivo studies showed that BsEV treatment significantly inhibited the growth of OVCAR-8/MDR and OVCAR-8 tumors. Additionally, OVCAR-8/MDR tumors showed a trend towards a greater sensitivity to BsEVs compared to OVCAR tumors. In summary, this study demonstrates that BsEVs hold tremendous potential for cancer treatment, especially against MDR cancer cells.

LINC00707 promotes multidrug resistance of ovarian cancer cells by targeting the miR-382-5p/LRRK2 axis.

Multidrug resistance severely limits the efficacy of ovarian cancer (OC) treatment. Recent studies have revealed the carcinogenic role of LINC00707 RNA. However, the role of LINC00707 in the development of multidrug resistance in OC has not been clarified. Therefore, the aim of this study was to investigate the relationship between LINC00707 and multidrug resistance in OC, which can facilitate the development of new therapeutic agents for effectively addressing this issue. The RNA expression of LINC00707, miR-382-5p and leucine-rich repeat kinase 2 (LRRK2) in SKOV3 (a human OC cell line) cells was detected by qRT-PCR. The effects of LINC00707 on the proliferation and viability of SKOV3 cells were determined by MTT assay and colony formation assay. The interaction of LINC00707, miR-382-5p, and LRRK2 was bioinformatically predicted and verified with dual-luciferase reporter assay. In addition, the effect of LINC00707 on drug resistance in SKOV3 cells through targeting the miR-382-5p/LRRK2 axis was explored. The expression of LINC00707 and LRRK2 was significantly increased in SKOV3 cells, while miR-382-5p expression was significantly decreased. The results of bioinformatic prediction and colony formation assay demonstrated that LINC00707 could regulate LRRK2 expression in SKOV3 cells by targeting miR-382-5p. Additionally, knockdown of LINC00707 markedly increased expression of miR-382-5p and decreased that of LRRK2, increased cell proliferation and viability, as well as sensitivity to chemotherapeutic agents in SKOV3 cells. Notably, these manifestations were more obvious with simultaneous knockdown of LINC00707 and miR-382-5p compared with knockdown of LINC00707 alone. LINC00707 is overexpressed in SKOV3 cells and promotes SKOV3 cell proliferation and resistance to chemotherapeutic drugs via targeting the miR-382-5p/LRRK2 axis.

Programmed-response cross-linked nanocarrier for multidrug-resistant ovarian cancer treatment

The application of numerous chemotherapeutic drugs has been limited due to poor solubility, adverse side effects, and even multidrug resistance in patients. Polymeric micelles with reversibly cross-linked structures provide a promising solution to these issues. Herein, we optimized and synthesized programable-released disulfide cross-linked micelle (PDCM) based on our previous well-defined dendrimers to deliver the antitumor drug betulinic acid (BA) and paclitaxel (PDCM@PTX) and evaluated the therapeutic efficacy of multidrug-resistant (MDR) simulative orthotopic intraperitoneal ovarian cancer mice models. Comprehensive results demonstrated that PDCM@PTX formed stable nanoparticles able to improve the pharmacokinetic profile and circulation time of PTX, allowing for increased tumor penetration. Furthermore, in the tumor microenvironment, the programable-switches (ester bonds and disulfide cross-linking) of PDCM@PTX were cleaved by the high concentration of glutathione (tumor microenvironment) and esterase (intracellular) present in the tumor, allowing for in situ release of PTX and BA, resulting in intensive therapeutic efficacy in MDR ovarian cancer.

Terfenadine resensitizes doxorubicin activity in drug-resistant ovarian cancer cells via an inhibition of CaMKII/CREB1 mediated ABCB1 expression.

Ovarian cancer is one of the most lethal gynecological malignancies. Recurrence or acquired chemoresistance is the leading cause of ovarian cancer therapy failure. Overexpression of ATP-binding cassette subfamily B member 1 (ABCB1), commonly known as P-glycoprotein, correlates closely with multidrug resistance (MDR). However, the mechanism underlying aberrant ABCB1 expression remains unknown. Using a quantitative high-throughput combinational screen, we identified that terfenadine restored doxorubicin sensitivity in an MDR ovarian cancer cell line. In addition, RNA-seq data revealed that the Ca2+-mediated signaling pathway in the MDR cells was abnormally regulated. Moreover, our research demonstrated that terfenadine directly bound to CAMKIID to prevent its autophosphorylation and inhibit the activation of the cAMP-responsive element-binding protein 1 (CREB1)-mediated pathway. Direct inhibition of CAMKII or CREB1 had the same phenotypic effects as terfenadine in the combined treatment, including lower expression of ABCB1 and baculoviral IAP repeat-containing 5 (BIRC5, also known as survivin) and increased doxorubicin-induced apoptosis. In this study, we demonstrate that aberrant regulation of the Ca2+-mediated CAMKIID/CREB1 pathway contributes to ABCB1 over-expression and MDR creation and that CAMKIID and CREB1 are attractive targets for restoring doxorubicin efficacy in ABCB1-mediated MDR ovarian cancer.

Establishment and Characterization of a Novel Multidrug Resistant Human Ovarian Cancer Cell Line With Heterogenous MRP7 Overexpression.

Ovarian cancer is one of the leading female malignancies which accounts for the highest mortality rate among gynecologic cancers. Surgical cytoreduction followed by chemotherapy is the mainstay of treatment. However, patients with recurrent ovarian cancer are likely to exhibit resistance to chemotherapy due to reduced sensitivity to chemotherapeutic drugs. Adenosine triphosphate (ATP)-binding cassette (ABC) transporters have been extensively studied as multidrug resistance (MDR) mediators since they are responsible for the efflux of various anticancer drugs. Multidrug resistance protein 7 (MRP7, or ABCC10) was discovered in 2001 and revealed to transport chemotherapeutic drugs. Till now, only limited knowledge was obtained regarding its roles in ovarian cancer. In this study, we established an MRP7-overexpressing ovarian cancer cell line SKOV3/MRP7 via transfecting recombinant MRP7 plasmids. The SKOV3/MRP7 cell line was resistant to multiple anticancer drugs including paclitaxel, docetaxel, vincristine and vinorelbine with a maximum of 8-fold resistance. Biological function of MRP7 protein was further determined by efflux-accumulation assays. Additionally, MTT results showed that the drug resistance of the SKOV3/MRP7 cells was reversed by cepharanthine, a known inhibitor of MRP7. Moreover, we also found that the overexpression of MRP7 enhanced the migration and epithelial-mesenchymal transition (EMT) induction. In conclusion, we established an in vitro model of MDR in ovarian cancer and suggested MRP7 overexpression as the leading mechanism of chemoresistance in this cell line. Our results demonstrated the potential relationship between MRP7 and ovarian cancer MDR.

Long Noncoding RNA CTD-2589M5.4 Inhibits Ovarian Cancer Cell Proliferation, Migration, and Invasion Via Downregulation of the Extracellular Matrix-Receptor Interaction Pathway.

Background: The authors' previous study showed that the long noncoding RNA CTD-2589M5.4 was significantly upregulated in multidrug-resistant ovarian cancer cells. However, the role of CTD-2589M5.4 in the progression of ovarian cancer remains unclear. The purpose of this current study was to illuminate the biological function and possible mechanism of CTD-2589M5.4 in ovarian cancer development. Materials and Methods: The expression of CTD-2589M5.4 was examined via real-time quantitative PCR in primary ovarian cancer tissues (POCTs) and ovarian cancer cell lines. The biological function of CTD-2589M5.4 was analyzed via CCK-8 proliferation, wound healing, transwell, and flow cytometry assays in CTD-2589M5.4-overexpressed/silenced and control ovarian cancer cells. The mechanism of CTD-2589M5.4 function in ovarian cancer progression was analyzed utilizing high-throughput RNA-sequencing, Kyoto Encyclopedia of Genes and Genomes analysis, qRT-PCR, Western blot, and rescue experiments. Results: CTD-2589M5.4 expression was decreased in the POCTs and ovarian cancer cells compared with the normal ovarian tissues (p < 0.05) and normal ovarian epithelial cells (p < 0.05). Overexpression of CTD-2589M5.4 inhibited the proliferation, invasion, and migration of ovarian cancer cells, while knockdown of CTD-2589M5.4 had the opposite effect. Furthermore, a total of 750 and 233 genes were notably upregulated and downregulated, respectively, in the CTD-2589M5.4-overexpressed A2780 cells, while the extracellular matrix (ECM)-receptor interaction pathway was significantly downregulated. In addition, overexpression of fibronectin 1 significantly abrogated the tumor suppressive function of CTD-2589M5.4. Conclusions: This study demonstrated that CTD-2589M5.4 could inhibit ovarian cancer cell proliferation, invasion, and migration, at least partially by way of downregulating the ECM-receptor interaction pathway, therefore providing a potential therapeutic target for the prevention and/or treatment of ovarian cancer.

Heat Shock Protein 90 Triggers Multi-Drug Resistance of Ovarian Cancer via AKT/GSK3β/β-Catenin Signaling

Ovarian cancer is the most lethal gynaecologic tumor, with which multi-drug resistance as the major therapeutic hindrance. Heat shock protein 90 (Hsp90) has been involved in cancer malignant behaviors. However, its role and mechanism in multi-drug resistance of ovarian cancer remains poorly understood. Our results demonstrated that Hsp90 was overexpressed in multi-drug resistant ovarian cancer cells. Hsp90 downregulation by shHsp90 or inhibitor BIIB021 increased the sensitivity of multi-drug resistant ovarian cancer cells to paclitaxel and cisplatin, and augmented the drugs-induced apoptosis. Hsp90 positively regulated the expressions of multi-drug resistance protein 1 (P-gp/MDR1), breast cancer resistance protein (BCRP), Survivin and Bcl-2 expressions closely associated with multi-drug resistance. Moreover, overexpression of Hsp90 promoted β-catenin accumulation, while Hsp90 downregulation decreased the accumulation, nuclear translocation and transcriptional activity of β-catenin. We also identified that β-catenin was responsible for Hsp90-mediated expressions of P-gp, BCRP, Survivin, and Bcl-2. Furthermore, Hsp90 enhanced the AKT/GSK3β signaling, and AKT signaling played a critical role in Hsp90-induced accumulation and transcriptional activity of β-catenin, as well as multi-drug resistance to paclitaxel and cisplatin. In conclusion, Hsp90 enhanced the AKT/GSK3β/β-catenin signaling to induce multi-drug resistance of ovarian cancer. Suppressing Hsp90 chemosensitized multi-drug resistant ovarian cancer cells via impairing the AKT/GSK3β/β-catenin signaling, providing a promising therapeutic strategy for a successful treatment of ovarian cancer.

A Novel Targeted Co-Delivery Nanosystem for Enhanced Ovarian Cancer Treatment Via Multidrug Resistance Reversion

Multidrug resistance (MDR) is a major challenge in successful chemotherapy treatment of ovarian cancer patients, and 50%–75% of ovarian cancer patients eventually relapse because of MDR. One of an effective strategy for treating MDR and improving therapeutic efficiency of ovarian cancer is to use nanotechnology-based targeted drug delivery systems. This study developed a novel hyaluronic acid (HA)-targeted co-delivery nanosystem using functionalized mesoporous silica nanoparticle–coated gold nanorods (HA-PTX/let-7a-GNR@MSN) to co-deliver paclitaxel (PTX), a hydrophobic chemotherapy drug, and lethal-7a (let-7a), a microRNA (miR), to overcome MDR in ovarian cancer. We also analyzed the molecular mechanism of miR let-7a in ovarian cancer treatment. The nanosystem enabled protective drug delivery and stable binding of PTX and miRs. Analysis of drug-resistant SKOV3TR cells and an SKOV3TR xenograft model in BALB/c-nude mice showed significant P-glycoprotein downregulation in heterogeneous tumor sites, PTX release, and apoptosis induction later. Results showed that HA-modified nanocomposites can specifically bind to the CD44 receptor, which is highly expressed in SKOV3/SKOV3 TR cells, achieving effective cell uptake and 150% enhancement of tumor site permeability. More importantly, this nanosystem resulted in synergistic inhibition of ovarian tumor growth. Overall, the data provide a model for overcoming PTX resistance in ovarian cancer.

Human La Protein: An RNA-Binding Protein Involved in Ovarian Cancer Development and Multidrug Resistance.

Multidrug resistance is the main cause of chemotherapy failure and death in patients with advanced ovarian cancer. Drug resistance is a problem that must be solved to improve the survival rate of patients with advanced ovarian cancer. The RNA-binding protein La and the La-related protein family are highly expressed in various malignant tumors, including ovarian cancer. This article reviews the mechanisms of La protein in tumorigenesis, development, and drug resistance. High La protein expression in tumor cells promotes tumor proliferation, invasion, and migration; disrupts cell cycle; and inhibits tumor cell apoptosis caused by chemotherapeutic drugs through various pathways, resulting in chemotherapy resistance in ovarian cancer. Further study of the role of La protein in ovarian cancer multidrug resistance may be conducive to the development of human La protein-specific inhibitors that suppress ovarian cancer drug resistance.

Process optimization for green synthesis of gold nanoparticles mediated by extract of Hygrophila spinosa T. Anders and their biological applications

Plant extract-mediated green synthesis of gold nanoparticles (AuNPs) and their biomedical application is currently gaining huge interest in the field of nanotechnology . In the present study, AuNPs were synthesized using Hygrophila spinosa aqueous extract (HSAE). The formation of AuNPs was confirmed by observing color change and characteristic absorbance peak for surface plasmon resonance by UV–Vis spectroscopy. Different reaction parameters such as HSAE concentration, salt concentration, pH, reaction time and temperature were optimized for biosynthesis of AuNPs. The NPs were characterized for particle size, surface morphology , crystallinity , elemental composition and surface functionalities. Cytotoxicity of the AuNPs was studied against different cancer cell lines by MTT assay and antioxidant potential as total antioxidant capacity was also evaluated. The biosynthesized AuNPs were small in size and negatively charged. Phytochemical screening of HSAE, and FTIR spectrum of synthesized AuNPs demonstrated participation of various groups of chemical compounds as capping and stabilizing agents in biosynthesis of AuNPs. The green synthesized AuNPs exhibited significantly higher anticancer activity compared to HSAE against breast, ovarian, glioblastoma/brain and multi-drug resistant ovarian cancer cell lines. Antioxidant activity of the synthesized AuNPs was less than HSAE. The biosynthesized AuNPs could be studied further to access their potency in the treatment and imaging of various cancers. • Green synthesis of AuNPs has been carried out with Hygrophila spinosa aqueous extract (HSAE). • Concentration of HAuCl 4 solution, pH, reaction incubation temperature & time, and concentration of HSAE have been optimized for synthesis of AuNPs. • Characterization by UV–Vis, FTIR, SEM, TEM, EDS and XRD confirm that HSAE could synthesize AuNPs. • Synthesized AuNPs exhibited promising antioxidant and anticancer activities.

Abstract 3627: Development of CLENs for future treatment &amp; diagnostic detection using cell models of drug-resistant ovarian cancer

Abstract Current guidelines suggest the use of a platinum agent and a taxane as first line therapy for ovarian cancer where total surgical resection is limited. Liposomal preparations of these drugs have demonstrated therapeutic value by increasing drug uptake and reducing toxicity. The following research aims to improve target specificity by employing a multi-strategic approach to drug targeting and treatment in vitro. Cellular membrane lipid-extracted nanoliposomes (CLENs) were constructed in part from lipid extracts (LE) derived from the membrane of multidrug resistant ovarian cancer (SKOV-3-MDR) cell lines, and more conventional components of liposomes. Formulations of greatest interest were selected after comparing cellular uptake studies of conventional liposomes to various types of CLENs composed of mixed ratios of DOPC, cholesterol, and LE. Cellular uptake was measured by rhodamine fluorescence (RF) following 24 hours incubation in 48 well plates, where RF was used as an indicator of cellular uptake. To determine effectiveness of LE, formulations with and without synthetic cationic lipid DOTAP were compared. Flow cytometry was used to evaluate liposome binding. Additional studies include drug loading efficiency and SRB cytotoxicity studies involving cisplatin, and the effect of additional inclusion of MAG-C (magnetic material) in the SKOV-3 lipid extract-containing liposomes. CLENs containing 15% LE demonstrated greater uptake compared to CLENs prepared with 0% and 5% LE content. Minimal uptake was observed in non-target cancer cell lines (prostate cancer-CRL-1740 and gliobastoma-U87MG), as well as with normal pancreas, non-malignant (hTERT) cell line. The fluorescence intensity values reported for SKOV-3-MDR, CRL-1740, U87-MG and hTERT, were 437 ± 153, 295 ± 67, 57 ± 6, and 29 ± 6, respectively. The additional inclusion of DOTAP showed significant cellular uptake with and without LE. Flow cytometry showed greater initial binding of CLENs to target cells when LE was included in preparations. Incorporation efficiency of cisplatin into SKOV-3 CLENS was 67%. Chemotherapy drug-loaded CLENs is an appealing vehicle as it addresses many parameters. Early findings suggest that CLENS is a suitable vehicle for targeting and treatment using a drug-resistant ovarian cancer cell line. CLENS allows for faster initial nanoparticle binding, cell-type specific uptake, and enhances cytotoxicity. Our encouraging results corroborate this theorem, showing greater targeting with reduced uptake by non-target cells. Additional studies involving MAG-C are currently underway. Citation Format: Negar Amini, Joshua Emerson, Jenel Clement. Development of CLENs for future treatment &amp; diagnostic detection using cell models of drug-resistant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3627.

3-acetyl-11-keto-beta-boswellic acid decreases the malignancy of taxol resistant human ovarian cancer by inhibiting multidrug resistance (MDR) proteins function

ObjectiveRecurrence of ovarian cancer is mainly due to multidrug resistance (MDR). 3-acetyl-11-keto-beta-boswellic acid (AKBA) could reverse the multidrug resistance in human ileocecal adenocarcinoma cells, but whether AKBA could modulate acquired MDR in ovarian cancer needs to be elucidated. MethodsThe current study examined the effect of AKBA on ovarian cancer MDR using a Taxol resistant human ovarian cancer cell line A2780/Taxol. Cell proliferation, migration and invasion, the intracellular accumulation of Rhodamine 123 and expression of MDR proteins were studiedin vitro. Furthermore, the effect of AKBA on oncogenicity of A2780/Taxol cells in nude mice xenograft model was studied. ResultsThe results showed that apart from its cytostatic and apoptosis-induction effect, AKBA could restrain A2780/Taxol cell migration and invasion. In addition, AKBA improved the sensitivity of A2780/Taxol cells to Taxol apparently, and the reversal of MDR by AKBA was evident by increasing intracellular Rhodamine 123 in cells. Furthermore, the anti-cancer potential of AKBA was evidenced as that AKBA treatment significantly slowed tumor growth and decreased the expression of P-gp, LRP, BCRP and MRP. ConclusionAbove results indicated that AKBA might be a potential compound to reverse MDR in human ovarian cancer.

Costunolide Inhibits the Growth of OAW42-A Multidrug-Resistant Human Ovarian Cancer Cells by Activating Apoptotic and Autophagic Pathways, Production of Reactive Oxygen Species (ROS), Cleaved Caspase-3 and Cleaved Caspase-9.

BackgroundWorldwide, ovarian cancer has a high mortality rate due to the difficulty in diagnosing early-stage disease and resistance to chemotherapy agents. Costunolide is a plant-derived sesquiterpene lactone with anti-oxidant properties. This study aimed to investigate the effects of costunolide on cell growth, apoptosis, autophagy, the production of reactive oxygen species (ROS), cleaved caspase-3, and cleaved caspase-9 on the multidrug-resistant ovarian cancer cell line, OAW42-A.Material/MethodsThe MTT assay determined the proliferation rate of OAW42-A multidrug-resistant ovarian cancer cells and the apoptosis rate was determined using propidium iodide (PI) staining. Autophagy was detected by measuring the expression of LC3 II. Fluorescence flow cytometry was used to measure the levels of reactive oxygen species (ROS) and the mitochondrial membrane potential. Protein expression of LC3 II, beclin 1, cleaved caspase-3, and cleaved caspase-9 were measured by Western blot.ResultsCostunolide treatment inhibited the growth of OAW42-A cells with an IC50 of 25 μM, resulted in apoptotic cell death, increased the expression of Bax, and decreased the expression of Bcl-2. Confocal electron microscopy showed that costunolide induced autophagy in the OAW42-A cells. Western blot showed that costunolide treatment of OAW42-A cells increased the expression of the LC3 II, beclin 1, cleaved caspase-3, and cleaved caspase-9. Costunolide treatment significantly increased the levels of ROS and reduced the OAW42-A cell mitochondrial membrane potential.ConclusionsCostunolide inhibited growth, apoptosis, ROS generation, and was associated with loss of mitochondrial membrane potential of OAW42-A multidrug-resistant ovarian cancer cells.

Combination of shikonin with paclitaxel overcomes multidrug resistance in human ovarian carcinoma cells in a P-gp-independent manner through enhanced ROS generation

BackgroundShikonin (SKN), a naphthoquinone compound, is isolated from Chinese herbal medicine Lithospermum root and has been studied as an anticancer drug candidate in human tumor models. This study is designed to investigate whether SKN can sensitize the therapeutic effect of paclitaxel (PTX) in drug-resistant human ovarian carcinoma cells.MethodsHuman ovarian carcinoma A2780 cell along with the paired PTX-resistant A2780/PTX cells were used. The effects of SKN, PTX or their combination on cell viability were conducted using Sulforhodamine B assay. P-glycoprotein (P-gp) expression was analyzed by flow cytometry after staining with P-gp-FITC anti-body. P-gp activity was determined by a fluorometric MDR assay kit or a rhodamine 123-based efflux assay, respectively. Apoptosis was evaluated by flow cytometry after Annexin V-FITC/PI co-staining. The effect of SKN, PTX or their combination on reactive oxygen species (ROS) generation and expression of pyruvate kinase M2 (PKM2) were investigated using flow cytometry or western blotting, respectively. PKM2 activity was detected by a Pyruvate Kinase Assay Kit.ResultsSKN/PTX co-treatment led to synergistically enhanced cytotoxicity and apoptosis in PTX-resistant ovarian cancer cells, indicating the circumvention of multidrug resistance (MDR) of PTX by SKN. Further study indicated that the MDR reversal effect of SKN was independent of inhibiting activity of the efflux transporter P-gp. Notably, SKN/PTX significantly increased the generation of intracellular ROS in A2780/PTX cells, and scavenging intracellular ROS blocked the sensitizing effects of SKN in PTX-induced cytotoxicity and apoptosis in A2780/PTX cells, but not in A2780 cells. Furthermore, SKN/PTX-induced downregulation of PKM2 (a key enzyme in glycolysis) and the suppression of its activity were inhibited by a ROS scavenger N-acetyl cysteine (NAC), suggesting that the synergy of the SKN/PTX combination may be not rely on PKM2 suppression.ConclusionsThese results reveal a P-gp-independent mechanism through ROS generation for the SKN/PTX combination to overcome MDR in ovarian cancer.

Expression of integrin α-6 is associated with multi drug resistance and prognosis in ovarian cancer.

Ovarian cancer is a serious threat to women's health. Multidrug resistance is a major cause of post-treatment relapse, metastasis, and even mortality. This characteristic severely restricts the survival of patients with ovarian cancer. Integrin α-6 (ITGA6) is a member of the adhesion molecule family that conducts signals through interactions between the extracellular domain and the matrix, serving important roles in cell adhesion-mediated drug resistance, which is considered to have a critical function in ovarian cancer drug resistance. The association between ITGA6 and ovarian cancer multidrug resistance has been investigated only rarely, to the best of our knowledge. Using RT-qPCR and immunohistochemistry, it was identified that ITGA6 is a central drug resistance gene, and that its expression was upregulated in cisplatin-resistant SKOV3 (SKOV3/DDP2), cisplatin-resistant A2780 (A2780/DDP) cells, and in 54 cases of drug-resistant tissues, as compared with in the controls. Furthermore, bioinformatics and text mining performed by Coremine Medical (http://www.coremine.com/medical/#search) confirmed that ITGA6 was significantly associated with ovarian cancer and drug resistance. Additionally, the high expression of ITGA6 is associated with a poor outcome. The present study provides the basis for further understanding the role of ITGA6 in the regulation of drug resistance in ovarian cancer, and demonstrates that it could be a potential marker for the prognosis of ovarian cancer.

S100A10 and Cancer Hallmarks: Structure, Functions, and its Emerging Role in Ovarian Cancer.

S100A10, which is also known as p11, is located in the plasma membrane and forms a heterotetramer with annexin A2. The heterotetramer, comprising of two subunits of annexin A2 and S100A10, activates the plasminogen activation pathway, which is involved in cellular repair of normal tissues. Increased expression of annexin A2 and S100A10 in cancer cells leads to increased levels of plasmin—which promotes the degradation of the extracellular matrix—increased angiogenesis, and the invasion of the surrounding organs. Although many studies have investigated the functional role of annexin A2 in cancer cells, including ovarian cancer, S100A10 has been less studied. We recently demonstrated that high stromal annexin A2 and high cytoplasmic S100A10 expression is associated with a 3.4-fold increased risk of progression and 7.9-fold risk of death in ovarian cancer patients. Other studies have linked S100A10 with multidrug resistance in ovarian cancer; however, no functional studies to date have been performed in ovarian cancer cells. This article reviews the current understanding of S100A10 function in cancer with a particular focus on ovarian cancer.

Ovarian cancer stem cell: A potential therapeutic target for overcoming multidrug resistance.

The cancer stem cell (CSC) model encompasses an advantageous paradigm that in recent decades provides a better elucidation for many important biological aspects of cancer initiation, progression, metastasis, and, more important, development of multidrug resistance (MDR). Such several other hematological malignancies and solid tumors and the identification and isolation of ovarian cancer stem cells (OV-CSCs) show that ovarian cancer also follows this hierarchical model. Gaining a better insight into CSC-mediated resistance holds promise for improving current ovarian cancer therapies and prolonging the survival of recurrent ovarian cancer patients in the future. Therefore, in this review, we will discuss some important mechanisms by which CSCs can escape chemotherapy, and then review the recent and growing body of evidence that supports the contribution of CSCs to MDR in ovarian cancer.

Abstract 5893: Expression and role of autophagy-associated p62 (SQSTM1) in multidrug-resistant ovarian cancer

Abstract Multidrug resistance is the major cause of treatment failure in ovarian cancer. p62 (SQSTM1) is a multifunctional protein involved in multiple cellular processes including proliferation, drug sensitivity and autophagy-associated cancer cell growth. p62 is a critical indicator of autophagic flux, which is inversely associated with autophagy activity. However, the role of p62 remains controversial in drug resistance in human ovarian cancer. In this study, we examined p62 expression by immunohistochemistry in a unique ovarian cancer tissue microarray (TMA), which was constructed with paired primary, metastatic, and recurrent tumor tissues from 26 individual patients. Results showed that both the metastatic and recurrent tumor tissues expressed less p62 than the patient-matched primary tumor. A significant inverse correlation has been found between p62 expression and both the disease free survival and overall survival. In addition, multidrug resistant cancer cell lines expressed lower levels of p62 as compared with their parental drug sensitive cell lines. Importantly, cell viabilities determined by MTT assay after exposure to different concentrations of paclitaxel showed inhibition of autophagy or accumulation of p62 enhances paclitaxel sensitivity in ovarian cancer drug resistant cells. Furthermore, the wound healing assay exhibited that inhibition of autophagy significantly decreased multidrug resistant ovarian cancer cell migration in vitro. Collectively, these data highlight that autophagy pathway may be a promising therapeutic target to prevent metastasis, recurrence and to reverse drug resistance in ovarian cancer. Citation Format: Jinglu Wang, Cassandra Garbutt, Francis J Hornicek, Zhenfeng Duan. Expression and role of autophagy-associated p62 (SQSTM1) in multidrug-resistant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5893.

Abstract 4817: EP-100 sensitizes BRCA wild-type ovarian cancer cells to PARP inhibitor

Abstract EP-100 is a synthetic lytic peptide specific for targeting LHRH receptors on cancer cells that is being clinically tested for treatment of ovarian cancer. In this study, we aimed to identify combination approaches with EP-100 in ovarian cancer models. We carried out a series of in vitro (MTT assay, immunoblot analysis, Q-PCR, reverse phase protein array (RPPA), comet assay and immunofluorescence staining) and in vivo (orthotopic mouse model) experiments in ovarian cancer models to determine the biological effects of EP-100 alone and in combination with standard of care drugs. We first examined the cytotoxic effects of EP-100 alone on 8 ovarian cancer cell lines with variable expression level of LHRH receptors and the IC50 values ranged from 0.5 to 2.0 µM. We then tested the effect of combining EP-100 with standard drugs (e.g., cisplatin, paclitaxel, doxorubicin, topotecan, and olaparib) on ovarian cancer cells. Of those drugs, we found that combination of EP-100 and olaparib was highly synergistic in drug sensitive and multi-drug resistant ovarian cancer cell lines (HeyA8, HeyA8-MDR, A2780, and A2780CP20). The combination indices (CI) were &amp;lt; 0.9 at the ED50 level. Furthermore, the nuclear foci of γH2AX were significantly increased in combination group of EP100 and olaparib after 24 h incubation compared with control, EP-100 alone, or olaparib alone groups (p &amp;lt; 0.0001, ANOVA). In addition, there was increased DNA accumulation in tails using comet assay after treating cells with EP-100 and olaparib for 24 h (p &amp;lt; 0.001, ANOVA). RPPA results identified that PI3K/AKT pathway can be blocked significantly by the combination treatment. The study in HeyA8 xenograft mouse models showed that mice treated with EP-100 and olaparib had the lowest tumor weight (0.06 ± 0.05 g) compared with those treated with vehicle (1.19 ± 0.39 g, p &amp;lt; 0.008), EP-100 alone (0.62 ± 0.28 g, p &amp;lt; 0.008), and olaparib alone (0.50 ± 0.22 g, p &amp;lt; 0.01). EP-100 has efficacy in preclinical models of ovarian cancer, especially in combination with olaparib. Our findings suggested that combining EP-100 with olaparib could be a promising therapeutic strategy for ovarian cancer. Citation Format: Shaolin Ma, Sunila Pradeep, Sherry Wu, Mark Seungwook Kim, Wei Hu, Selanere Mangala, Robert L. Coleman, Anil K. Sood. EP-100 sensitizes BRCA wild-type ovarian cancer cells to PARP inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4817.