Cisplatin-resistant Ovarian Cancer Research Articles

Abstract 2668: Long non-cording RNA TUG1 promotes cisplatin resistance in ovarian cancer via DNA polymerase eta

Abstract Ovarian cancer (OVCA) is the most malignant gynecologic cancer. Despite the use of surgery and platinum-based chemotherapy, the 5-year survival rate is approximately 30% at the time of diagnosis. Cisplatin inhibits DNA synthesis by cross-linking DNA and then induces cell apoptosis. However, cisplatin resistance often causes treatment failure and tumor relapse in OVCA patients. To overcome the cisplatin resistance in OVCAs, we studied the mechanism of chemoresistance by a long non-coding RNA (lncRNA), TUG1 (taurine upregulated gene 1), which is associated with carcinogenesis and drug sensitivity in OVCAs. The expression level of TUG1 in cisplatin-resistant OVCA clinical samples is significantly higher than that of cisplatin-sensitive samples by public database. A depletion of TUG1 increased the sensitivity of OVCA cells to cisplatin together with upregulation of a set of miRNAs in vitro. We examined the targets of miRNAs and found that TUG1 depletion downregulates DNA polymerase eta (Polη) by upregulating the miRNAs. Polη is a major translesion DNA synthesis (TLS) DNA polymerase, which bypasses DNA lesions produced by DNA damaging agents and helps DNA replication. The expression level of Polη showed a positive correlation with that of TUG1 in OVCA clinical samples. Overexpression of Polη recovered cisplatin resistance in TUG1-depleted cells. Finally, cisplatin treatment combined with TUG1 depletion effectively inhibited tumor growth in xenograft mouse models, indicating the efficacy of TUG1 depletion in vivo. Our data provide a strong rationale for targeting TUG1 as a novel therapeutic approach to overcome cisplatin resistance in OVCA. Citation Format: Ryosuke Sonobe. Long non-cording RNA TUG1 promotes cisplatin resistance in ovarian cancer via DNA polymerase eta [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 2668.

Abstract 1684: Plasminogen activator inhibitor-1 (PAI-1) promotes cisplatin resistance in ovarian cancer cells by inhibiting ROS-mediated apoptosis and ferroptosis

Abstract Resistance to platinum-based chemotherapy is one of major causes of therapy failure and tumor recurrence in ovarian cancer patients. However, the molecular mechanism of platinum resistance is not fully understood. Here, we compared gene expression between cisplatin-sensitive and -resistant ovarian cancer cells using gene expression microarray analysis and found the significantly up-regulated expression of SERPINE1 encoding plasminogen activator inhibitor-1 (PAI-1), a serine protease regulating the fibrinolysis and extracelluar matrix, in cisplatin-resistant ovarian cancer cells. The correlation of high PAI-1 expression with low cisplatin sensitivity was confirmed in ovarian cancer cells. PAI-1 overexpression in ovarian cancer cells significantly decreased the sensitivity to cisplatin, whereas PAI-1 down-regulation by SERPINE1 siRNA or PAI-1 inhibitor increased cisplatin sensitivity. PAI-1 inhibited cisplatin-induced apoptosis in ovarian cancer cells by suppressing reactive oxygen species (ROS) production and DNA damage. PAI-1 also decreased cisplatin-induced ferroptosis through the upregulation of GPX4 levels. Furthermore, Kaplan-Meier survival analysis using TGGA data demonstrated that high PAI-1 expression was significantly associated with shorter platinum-free survival of patients with ovarian cancer. Collectively, these results illustrate that PAI-1 promotes cisplatin resistance in ovarian cancer cells by inhibiting ROS-mediated apoptosis and ferroptosis, suggesting that targeting PAI-1 increases the sensitivity to cisplatin in ovarian cancer. Citation Format: Mi Jeong Kwon, Ha Yeong Chae, So Young Lee, Shin Ung Kang, Tae Woong Jung, Soo Youn Cho, Jinil Han, Hyojin Jeong, Chang Ohk Sung, Young Kee Shin. Plasminogen activator inhibitor-1 (PAI-1) promotes cisplatin resistance in ovarian cancer cells by inhibiting ROS-mediated apoptosis and ferroptosis [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 1684.

Abstract 4944: Evaluating the efficacy of spermine analogue ivospemin (SBP-101) in combination with chemotherapy in ovarian cancer

Abstract Polyamines are small cationic alkylamines that play critical roles in essential cellular processes governing growth and proliferation. As such, cancers are fully reliant on increased polyamine pools maintained through dysregulation of polyamine metabolism. Pharmaceutical modulation of polyamine metabolism is a promising avenue in cancer therapeutics and has been attempted with enzyme inhibitors, including DFMO (difluoromethylornithine), and polyamine analogues. Ivospemin is a spermine analogue that has shown efficacy in slowing pancreatic and ovarian tumor progression both in vitro and in vivo and demonstrated encouraging results in pancreatic cancer clinical trials. We have shown that ivospemin decreases polyamine content through depression of the activity of the polyamine biosynthetic enzyme ornithine decarboxylase (ODC) in a variety of cancer cell lines. Treatment of the VDID8+ murine ovarian cancer model with ivospemin resulted in a marked increase in survival. Here we examine the potential of combining ivospemin and chemotherapeutic agents that are used to treat cisplatin-resistant ovarian cancer. Treatment with gemcitabine, topotecan, and doxorubicin increased the in vitro toxicity of ivospemin, while paclitaxel and docetaxel did not have any added benefit over ivospemin alone. Using the VDID8+ model, we further evaluated the efficacy of ivospemin in combination with gemcitabine, topotecan, and doxorubicin in vivo. Ascites fluid was used as a marker of tumor burden and evaluated for polyamine content. Addition of ivospemin improved the survival of mice treated with any of the three chemotherapeutics. The ivospemin and doxorubicin combination mice had the greatest median survival time; this combination is being further evaluated in mechanistic studies and additional murine studies. Ovarian cancers have extremely immunosuppressive tumor microenvironments (TME) and metabolic reprogramming of the TME to reduce immunosuppressive phenotypes is a promising approach for treatment. Sustained elevation of polyamine levels supports an immunosuppressive TME, and evidence suggests that pharmacologic depletion of polyamines may reduce immunosuppressive phenotypes. DFMO treatment in the immunosuppressive VDID8+ model influences the immune cells of the TME, and we therefore are investigating the combination of ivospemin and DFMO in ovarian cancer. In addition to the cooperativity of ivospemin and chemotherapeutic agents, we have observed a cooperative antiproliferative response in ovarian cancer cells following DFMO and ivospemin cotreatment. Together, these studies suggest the potential of polyamine modulation by ivospemin and DFMO in combination with standard of care chemotherapy. Future studies will determine influences on the immune microenvironment and will evaluate cooperativity between ivospemin, DFMO, and chemotherapy. Citation Format: Cassandra E. Holbert, Jackson R. Foley, Tracy Murray Stewart, Michael J. Walker, Elizabeth Bruckheimer, Jennifer K. Simpson, Robert A. Casero. Evaluating the efficacy of spermine analogue ivospemin (SBP-101) in combination with chemotherapy in ovarian cancer. [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 4944.

AKT1 participates in ferroptosis vulnerability by driving autophagic degradation of FTH1 in cisplatin-resistant ovarian cancer.

Resistance to cisplatin (DDP)-based chemotherapy is an important reason for the failure of ovarian cancer treatment. However, tumor cells resistant to chemotherapy may expose vulnerability to other cell death pathways. Here, we found that DDP-resistant ovarian cancer cells are more susceptible to erastin-induced ferroptosis. It should be noted that this vulnerability does not depend on the weakening of classical ferroptosis defense proteins, but is caused by the reduction of ferritin heavy chain (FTH1). DDP-resistant ovarian cancer cells maintain a high level of autophagy to escape the pressure of chemotherapy, which ultimately leads to increased autophagic degradation of FTH1. We further revealed that the loss of AKT1 was the reason for the increased autophagy level of DDP-resistant ovarian cancer cells. Our study provides new insights into reversing DDP resistance in ovarian cancer by targeting ferroptosis pathway, and AKT1 may be a molecular marker of susceptibility to ferroptosis.

A platinum(II) complex HY1-Pt overcomes cisplatin-induced resistance and attenuates metastasis of epithelial ovarian cancer by cancer cell stemness inhibition.

Tumor recurrence, acquired resistance and metastasis have severely limited the effect of clinical treatments for epithelial ovarian cancer. Recent researches reveal that cancer stem cells play important roles in the process of cisplatin-induced resistance and cancer cell metastasis. A platinum(II) complex (HY1-Pt) owning casein kinase 2 specificity reported in our recent research was herein applied to treat cisplatin-sensitive and cisplatin-resistant epithelial ovarian cancers, respectively, anticipating to achieve high anti-tumor efficacy. HY1-Pt showed highly efficient anti-tumor effect with low toxicity for either cisplatin-sensitive or cisplatin-resistant epithelial ovarian cancer both in vitro and in vivo. Biological studies indicated that HY1-Pt as a casein kinase 2 inhibitor could effectively overcome cisplatin resistance through the signaling pathway of Wnt/β-catenin by inhibiting expression of the signature genes of cancer stemness cells in A2780/CDDP cells. Moreover, HY1-Pt could suppress tumor migration and invasion in vitro and in vivo, further proving that HY1-Pt can be a potent novel platinum(II) agent for cisplatin-resistant epithelial ovarian cancer treatment.

CRGD-targeted heparin nanoparticles for effective dual drug treatment of cisplatin-resistant ovarian cancer.

Resistance to the chemotherapeutic agent cisplatin (DDP) is the primary reason for invalid chemotherapy of ovarian cancer. Given the complex mechanisms underlying chemo-resistance, the design of combination therapies based on blocking multiple mechanisms is a rationale to synergistically elevate therapeutic effect for effectively overcoming cancer chemo-resistance. Herein, we demonstrated a multifunctional nanoparticle (DDP-Ola@HR), which could simultaneously co-deliver DDP and Olaparib (Ola, DNA damage repair inhibitor) using targeted ligand cRGD peptide modified with heparin (HR) as nanocarrier, enabling the concurrent tackling of multiple resistance mechanisms to effectively inhibit the growth and metastasis of DDP-resistant ovarian cancer. In combination strategy, heparin could suppress the function of multidrug resistance-associated protein 2 (MRP2) and P-glycoprotein (P-gp) to promote the intracellular accumulation of DDP and Ola by specifically binding with heparanase (HPSE) to down-regulate PI3K/AKT/mTOR signaling pathway, and simultaneously served as a carrier combined with Ola to synergistically enhance the anti-proliferation ability of DDP for resistant ovarian cancer, thus achieving great therapeutic efficacy. Our DDP-Ola@HR could provide a simple and multifunctional combination strategy to trigger an anticipated cascading effect, thus effectively overcoming the chemo-resistance of ovarian cancer.

Promising effect of cisplatin and melatonin combination on the inhibition of cisplatin resistance in ovarian cancer

Background: Ovarian cancer management has not yet given a satisfactory result, and the recurrence rate is still high. One of the reasons for this is resistance to chemotherapy. Melatonin and cisplatin may be involved in the chemotherapy resistance of ovarian cancer. Methods: A laboratory experiment was performed using melatonin and cisplatin in the SKOV3 cell, from September 2020 to November 2021 at the SCTE and Integrated Laboratory & Research Center Universitas Indonesia. Several variables were used, such as doxorubicin, melatonin, cisplatin, and combination of cisplatin and melatonin at several concentrations (1×, 3/4×, 1/2×, and 1/4×). A total of 24 samples were included and divided into 8 groups. The IC50 values of melatonin, doxorubicin, and cisplatin as well as cell viability was calculated via MTS assay. Subsequently, flow cytometry was performed to assess the effect of cisplatin and melatonin on the mechanisms of CTR1, p-glycoprotein, GSH, ERCC1, e-cadherin, and apoptosis. Analysis of variance and Bonferroni test were employed for the study. Results: The IC50 values of melatonin, cisplatin, and doxorubicin were 1.841 mM, 117.5 mM, and 14.72 mM, respectively. The combination groups of cisplatin and melatonin reduced cell viability; decreased the CTR1 mean (19.73), Pgp (6.7), GSH (11.73), and ERCC1 (4.27) in the combination 1 (C1) group; and increased e-cadherin (32.2) and annexin V (53.57) also in the combination 1 (C1) group. Conclusions: The combination of melatonin and cisplatin might have an impact on drug resistance via several mechanisms in ovarian cancer.

Anlotinib induces apoptosis and secondgrowth/mitosis phase block in cisplatin-resistant ovarian cancer cells via the aurorakinaseA/p53 pathway.

Cisplatin (DDP) resistance in ovarian cancer (OC) patients usually leads to treatment failure and increased mortality. Anlotinib has been shown to improve progression-free survival and overall survival in patients with platinum-resistant ovarian cancer, but the mechanism is unclear. This study aims to explore the mechanism by which anlotinib ameliorates platinum resistance in OC cells. Cell viability was detected by the 3-4,5-dimethylthiazol-2,5-diphenyltetrazolium bromide (MTT) method, and the apoptosis rate and changes in the cell cycle distribution were evaluated by flow cytometry. Bioinformatics analysis was used to predict the potential gene target of anlotinib in DDP-resistance SKOV3 cells, and its expression was verifies it by RT-qPCR, western blotting and immunofluorescence staining. Finally, ovarian cancer cells overexpressing AURKA were constructed, and the predicted results were verified by animal experiments. Anlotinib effectively induced apoptosis and G2/M arrest in OC cells and decreased the proportion of EdU-positive cells. AURKA was identified as a possible key target of anlotinib for inhibiting tumorigenic behaviors in SKOV3/DDP cells. Through combined immunofluorescence and western blot analyses, it was demonstrated that anlotinib could effectively inhibit the protein expression of AURKA and upregulate the expression of p53/p21, CDK1, and Bax protein. After overexpression of AURKA in OC cells, the induction of apoptosis and G2/M arrest by anlotinib were significantly inhibited. Anlotinib also effectively inhibited the growth of tumors in nude mice injected with OC cells. This study demonstrated that anlotinib can induce apoptosis and G2/M arrest in cisplatin-resistant ovarian cancer cells through the AURKA/p53 pathway.

Targeting ATP Synthase by Bedaquiline as a Therapeutic Strategy to Sensitize Ovarian Cancer to Cisplatin

Cisplatin is a common chemotherapeutic drug for treating ovarian cancer, but its clinical efficacy is hampered by intrinsic and acquired resistance. Previous studies had shown inhibiting oxidative phosphorylation overcomes cisplatin resistance in ovarian cancer. Studies reveal that bedaquiline, a clinically available antimicrobial drug, inhibits cancer via targeting mitochondria. This study systematically assessed the efficacy of bedaquiline in ovarian cancer and its underlying mechanism. Using a panel of ovarian cancer cell lines and normal ovary cells, we demonstrated bedaquiline is selective for anti-ovarian cancer activities. Furthermore, the sensitivity varied among different ovarian cancer cell lines regardless of their sensitivity to cisplatin. Bedaquiline inhibited growth, survival and migration, through decreasing levels of ATP synthase subunit, complex V activity, mitochondrial respiration and ATP. We further found that ovarian cancer displayed increased levels of ATP, oxygen consumption rate (OCR), complex V activity and ATP synthase subunits compared to normal counterpart. Combination index analysis showed that bedaquiline and cisplatin is synergistic. Bedaquiline remarkably enhanced the efficacy of cisplatin in inhibiting ovarian cancer growth in mice. Our study provides evidence to repurpose bedaquiline for ovarian cancer treatment and suggests that ATP synthase is a selective target to overcome cisplatin resistance in ovarian cancer.

Shikonin and cisplatin synergistically overcome cisplatin resistance of ovarian cancer by inducing ferroptosis via upregulation of HMOX1 to promote Fe2+ accumulation

BackgroundCisplatin-based chemotherapy often results in ovarian cancer (OC) chemical resistance and treatment failure. The combination of natural compounds with platinum-based agents is a new strategy for overcoming cisplatin resistance. At present, the synergistic effects and mechanism of combination of shikonin and cisplatin to overcome cisplatin resistance in OC are still unknown. PurposeThis study was to evaluate the synergistic effects of shikonin and cisplatin on cisplatin-resistant OC cells and to assess the underlying molecular basis for these effects. MethodsCell counting kit-8 assay, colony-formation assay, proteomic analysis, reactive oxygen species (ROS) detection, lipid peroxidation (LPO) detection, Fe2+ detection, western blot, and quantitative real-time reverse transcription PCR (qRT-PCR) were performed to evaluate the effects of shikonin and cisplatin on cisplatin-resistant OC cells. Underlying mechanisms of action were investigated in vitro using small molecule inhibitors and siRNA. In vivo, the effect of shikonin and cisplatin combination on tumor growth in BALB/c nude mice was evaluated, with tumor immunohistochemical (IHC) staining performed to detect ferroptosis-related proteins. ResultsIn vitro, shikonin and cisplatin were shown to synergistically reduce the viability of cisplatin-resistant OC cells. Proteomic results demonstrated that the combination of the two drugs induced a ferroptotic process, as evidenced by increased levels of ROS, LPO, and Fe2+, with downregulation of glutathione peroxidase 4 (GPX4). Heme oxygenase 1 (HMOX1) inhibition and siRNA interference attenuated the combined effect of the two drugs on cell viability. Accumulation of Fe2+ was attenuated by siRNA interference of HMOX1. In vivo, combination treatment significantly inhibited the growth of subcutaneous tumors in BALB/c nude mice and increased the expression of ferroptosis-related proteins in tumor tissue. ConclusionWe report for the first time that the co-treatment of shikonin and cisplatin overcomes cisplatin resistance in OC through ferroptosis. Mechanistic analysis reveals the co-treatment induces ferroptosis through upregulation of HMOX1 that promotes Fe2+ accumulation.

Erratum to: circRNA circSnx12 confers Cisplatin chemoresistance to ovarian cancer by inhibiting ferroptosis through a miR-194-5p/SLC7A11 axis

Ovarian cancer (OC) is the most common gynecological malignancy worldwide, and chemoresistance occurs in most patients, resulting in treatment failure. A better understanding of the molecular processes underlying drug resistance is crucial for development of efficient therapies to improve OC patient outcomes. Circular RNAs (circRNAs) and ferroptosis play crucial roles in tumorigenesis and resistance to chemotherapy. However, little is known about the role(s) of circRNAs in regulating ferroptosis in OC. To gain insights into cisplatin resistance in OC, we studied the ferroptosis-associated circRNA circSnx12. We evaluated circSnx12 expression in OC cell lines and tissues that were susceptible or resistant to cisplatin using quantitative real-time PCR. We also conducted in vitro and in vivo assays examining the function and mechanism of lnc-LBCSs. Knockdown of circSnx12 rendered cisplatin-resistant OC cells more sensitive to cisplatin in vitro and in vivo by activating ferroptosis, which was at least partially abolished by downregulation of miR-194-5p. Molecular mechanics studies indicate that circSnx12 can be a molecular sponge of miR-194-5p, which targets SLC7A11. According to our findings, circSnx12 ameliorates cisplatin resistance by blocking ferroptosis via a miR-194-5p/SLC7A11 pathway. CircARNT2 may thus serve as an effective therapeutic target for overcoming cisplatin resistance in OC. [BMB Reports 2023; 56(3): 184-189].

Novel Homoleptic and Heteroleptic Pt(II) β‐oxodithiocinnamic ester Complexes: Synthesis, Characterization, Interactions with 9‐methylguanine and Antiproliferative Activity

AbstractThree new series of homoleptic and heteroleptic platinum(II) β‐oxodithiocinnamic ester complexes, [Pt(L1–L9)2], [Pt(L1–L9)(DMS)Cl] and [Pt(L1–L9)(DMSO)Cl], were synthesized and characterized using elemental analysis, mass spectrometry, and different NMR spectroscopy (1H, 13C{1H} and 195Pt). The β‐oxodithiocinnamic esters coordinate towards the platinum(II) centre as O,S‐bidentate chelating ligands. The structures of HL3, [Pt(L2)2], [Pt(L6)(DMS)Cl] as well as [Pt(L2)(DMSO)Cl] have been confirmed through the X‐ray crystallography, where the platinum(II) complexes exhibit a slightly distorted square planar geometry. In this article, we also investigated the solvolysis of three representative Pt(II) complexes, as well as the interaction with 9‐methylguanine as a DNA model system, by utilizing the LC‐ESI‐MS technique. A selection of the complexes was assessed for their use as anticancer agents, and cytotoxicity assays with these complexes showed modest toxicity on both Cisplatin sensitive and resistant ovarian cancer cell lines. However, the compounds cytotoxicity was not affected by the Cisplatin resistance mechanisms and a specific selection of the ligands may modify the cell line specificity.

Half sandwich-type osmium, ruthenium, iridium and rhodium complexes with bidentate glycosyl heterocyclic ligands induce cytostasis in platinum-resistant ovarian cancer cells and bacteriostasis in Gram-positive multiresistant bacteria.

The toxicity of and resistance to platinum complexes as cisplatin, oxaliplatin or carboplatin calls for the replacement of these therapeutic agents in clinical settings. We have previously identified a set of half sandwich-type osmium, ruthenium and iridium complexes with bidentate glycosyl heterocyclic ligands exerting specific cytostatic activity on cancer cells but not on non-transformed primary cells. The apolar nature of the complexes, conferred by large, apolar benzoyl protective groups on the hydroxyl groups of the carbohydrate moiety, was the main molecular feature to induce cytostasis. We exchanged the benzoyl protective groups to straight chain alkanoyl groups with varying length (3 to 7 carbon units) that increased the IC50 value as compared to the benzoyl-protected complexes and rendered the complexes toxic. These results suggest a need for aromatic groups in the molecule. The pyridine moiety of the bidentate ligand was exchanged for a quinoline group to enlarge the apolar surface of the molecule. This modification decreased the IC50 value of the complexes. The complexes containing [(η6-p-cymene)Ru(II)], [(η6-p-cymene)Os(II)] or [(η5-Cp*)Ir(III)] were biologically active unlike the complex containing [(η5-Cp*)Rh(III)]. The complexes with cytostatic activity were active on ovarian cancer (A2780, ID8), pancreatic adenocarcinoma (Capan2), sarcoma (Saos) and lymphoma cell lines (L428), but not on primary dermal fibroblasts and their activity was dependent on reactive oxygen species production. Importantly, these complexes were cytostatic on cisplatin-resistant A2780 ovarian cancer cells with similar IC50 values as on cisplatin-sensitive A2780 cells. In addition, the quinoline-containing Ru and Os complexes and the short chain alkanoyl-modified complexes (C3 and C4) proved to be bacteriostatic in multiresistant Gram-positive Enterococcus and Staphylococcus aureus isolates. Hereby, we identified a set of complexes with submicromolar to low micromolar inhibitory constants against a wide range of cancer cells, including platinum resistant cells and against multiresistant Gram-positive bacteria.

Identification of EMP1 as a critical gene for cisplatin resistance in ovarian cancer by using integrated bioinformatics analysis.

Cisplatin resistance is among the main reasons for the poor prognosis of ovarian cancer (OC) patients. Until now, effective biomarkers for predicting cisplatin resistance in OC and specific drugs for reversing this resistance are lacking. This study identified the critical gene associated with cisplatin resistance in OC and provided a potential target for overcoming this resistance. Differentially expressed genes between cisplatin-resistant and -sensitive OCs were identified by screening public datasets. Survival analysis was conducted to screen prognosis-related DEGs. CIBERSORT, ESTIMATE, and immune checkpoint genes were used to assess the association between EMP1 expression and tumor microenvironment features. CTRP and GDSC databases were employed to analyze the correlation between EMP1 expression and cisplatin resistance. Furthermore, immunohistochemistry, qPCR, Western blotting, siRNA interference, and the CCK8 assay were performed to verify the role of EMP1 in cisplatin resistance in vitro. Finally, xenograft mouse models were generated to further confirm the role of EMP1 in cisplatin resistance in vivo. EMP1 was identified as a critical gene associated with cisplatin resistance in OC. According to bioinformatics analyses, increased EMP1 expression was linked to higher stromal/ESTIMATE scores as well as greater ICG expression levels. The in vitro experiments showed that EMP1 was highly expressed in cisplatin-resistant OC tissues and cells, and silencing this EMP1 expression enhanced OC cell sensitivity to cisplatin. Finally, in vivo experiments confirmed that EMP1 promotes tumor growth and cisplatin resistance. EMP1 can act as a predictive biomarker for cisplatin resistance in OC and as a potential therapeutic target.

The small heat shock protein αB-Crystallin protects versus withaferin A-induced apoptosis and confers a more metastatic phenotype in cisplatin-resistant ovarian cancer cells.

Since a majority of ovarian tumors recur in a drug-resistant form leaving patients few treatment options, the goal of this study was to explore phenotypic and molecular characteristics of a cisplatin-resistant ovarian cancer cell line (OVCAR8R) as compared to its cisplatin-sensitive syngeneic counterpart (OVCAR8) and to explore the effectiveness of a novel chemotherapeutic, Withaferin A (WA). In addition to unique morphological characteristics, the small heat shock proteins (Hsps) αB-Crystallin (HspB5) and Hsp27 are constitutively expressed along with increased expression of vimentin in OVCAR8R cells, while OVCAR8 cells do not endogenously express these Hsps, supporting that Hsp overexpression may confer resistance to chemotherapy and promote more aggressive tumor types. WA increases apoptosis in a dose-dependent manner in OVCAR8 cells, while OVCAR8R cells remain more viable at comparable doses of WA coincident with the upregulation of αB-Crystallin. To determine the significance of αB-Crystallin in conferring a more aggressive phenotype, αB-Crystallin was silenced by CRISPR-Cas9 in OVCAR8R cells. The morphology of the OVCAR8R clones in which αB-Crystallin was silenced reverted to the morphology of the original cisplatin-sensitive OVCAR8 cells. Further, cisplatin-resistant OVCAR8R cells constitutively express higher levels of vimentin and migrate more readily than cisplatin-sensitive OVCAR8 and OVCAR8R cells in which αB-Crystallin was silenced. Transient overexpression of wildtype αB-Crystallin, but not a chaperone-defective-mutant, alters the morphology of these cells to closely resemble the cisplatin-resistant OVCAR8R cells and protects versus WA-induced apoptosis. Together, this research supports the potential effectiveness of WA as a therapy for ovarian cancer cells that have not yet acquired resistance to platinum-based therapies, and importantly, underscores that αB-Crystallin contributes to a more aggressive cellular phenotype and as such, may be a promising molecular target for a better clinical outcome.

Inhibition of Ceramide Kinase Is Effective against Cisplatin-Resistant Ovarian Cancer Cells by Regulating Ceramide and C1P Levels

Objective: Chemoresistance in ovarian cancer results in treatment failure, yet underlying mechanisms that regulate chemoresistance remain largely unclear. There is emerging evidence relating ovarian cancer drug resistance with bioactive sphingolipids and regulation of sphingolipid metabolism. This work investigated the expression and function of ceramide kinase (CerK), a lipid kinase that regulates central bioactive sphingolipids, in ovarian cancer, as well as the therapeutic potential of targeting CERK. Design: The levels of ceramide, ceramide 1-phosphate (C1P), and Cerk in ovarian cancer and normal counterparts were measured. Functions of Cerk in ovarian cancer were examined. Materials, Setting, Methods: Immunohistochemistry, ELISA, and mass spectrometry methods were used to measure the level of ceramides, C1P, and CerK in primary tissues. Proliferation and apoptosis assays were performed in ovarian cancer cells after CERK depletion, CERK overexpression, and NVP-231 treatment in the absence or presence of cisplatin. Results: Compared to normal ovarian cells, CerK and its mediating bioactive sphingolipids ceramide and C1P were decreased in ovarian cancer tissues. Interestingly, cisplatin-resistant ovarian cancer cells displayed increased CerK, decreased ceramide, and increased C1P, and furthermore, that CerK level was closely associated with ceramide and C1P levels in ovarian cancer cells. Functional analysis demonstrated that CerK overexpression was sufficient to promote growth and confer chemoresistance in ovarian cancer cells. CerK inhibition via both genetic and pharmacological approaches suppressed growth and induced apoptosis in cisplatin-resistant cells, and furthermore, this significantly augmented cisplatin’s efficacy. Limitations: The functional analysis of C1P was performed on in vitro ovarian cancer cells. In vivo studies were needed to further confirm the effects of CERK inhibition. Conclusions: Our work is the first to show the critical role of CerK as the underlying mechanism of ovarian cancer chemoresistance, through regulating ceramide and C1P.

Label-free-based quantitative proteomic analysis of the inhibition of cisplatin-resistant ovarian cancer cell proliferation by cucurbitacin B

BackgroundOvarian cancer is a serious threat to women's health, and resistance to chemotherapeutic drugs constitutes one of the principal reasons for ovarian cancer recurrence and the low overall survival rate. Therefore, it is of paramount importance to develop additional and more-effective drugs to combat resistance to chemotherapeutic drugs. Cucurbitacin B (CuB) is a natural compound found in food plants such as bitter gourd and pumpkin, and it manifests favorable antitumor effects on a variety of malignant tumors. PurposeThe present study aimed to determine the mechanism effects of CuB overcomes tumor-drug resistance in ovarian cancer. MethodsWe used CCK-8, Edu, flow cytometric assays and cisplatin-resistant ovarian cancer xenograft mouse model to evaluate the cellular proliferation, cellular apoptosis.and tumor growth. We subsequently applied a pharmacoproteomic approach to analyze the molecular mechanisms by which CuB inhibited the proliferation of cisplatin-resistant ovarian cancer cells. We also employed western blot and molecular docking experiments to verify elements of PI3K/Akt/mTOR pathway expression. ResultsWe found that CuB inhibited cellular proliferation and promoted apoptosis in cisplatin-resistant ovarian cancer cell lines. We discerned that CuB inhibited tumor growth of xenograft mouse tumors. We ascertained that treatment of A2780-DDP cells with CuB resulted in the differential expression of 305 proteins, with 202 proteins downregulated and 103 proteins upregulated. Of these proteins, the mTOR protein was significantly downregulated in the drug-treated group. We also found that CuB inhibited PI3K, Akt, and mTOR and that it activated cGAS expression upstream of PI3K and inhibited ATR expression. Molecular docking experiments revealed that CuB was hydrogen-bonded to mTOR proteins at Gly (2142) and Thr (2207), with a binding force of –10.2 kcal/mol. ConclusionOur study confirmed that cucurbitacin B inhibits the PI3K/Akt/mTOR signaling pathway, targets mTOR, suppresses the proliferation of cisplatin-resistant ovarian cancer cells.And we also found that cucurbitacin B induces DNA damage, activates cGASA and recruits IKBα,playing a crucial role in eliciting anti-tumor immunity. We herein uncovered a new use for CuB in inhibiting tumor-drug resistance, providing a novel approach to overcoming chemotherapeutic drug resistance in ovarian cancer.

Niclosamide (NA) overcomes cisplatin resistance in human ovarian cancer

Ovarian cancer (OC) is one of the most lethal malignancies of the female reproductive system. OC patients are usually diagnosed at advanced stages due to the lack of early diagnosis. The standard treatment for OC includes a combination of debulking surgery and platinum-taxane chemotherapy, while several targeted therapies have recently been approved for maintenance treatment. The vast majority of OC patients relapse with chemoresistant tumors after an initial response. Thus, there is an unmet clinical need to develop new therapeutic agents to overcome the chemoresistance of OC. The anti-parasite agent niclosamide (NA) has been repurposed as an anti-cancer agent and exerts potent anti-cancer activities in human cancers including OC. Here, we investigated whether NA could be repurposed as a therapeutic agent to overcome cisplatin-resistant (CR) in human OC cells. To this end, we first established two CR lines SKOV3CR and OVCAR8CR that exhibit the essential biological characteristics of cisplatin resistance in human cancer. We showed that NA inhibited cell proliferation, suppressed cell migration, and induced cell apoptosis in both CR lines at a low micromole range. Mechanistically, NA inhibited multiple cancer-related pathways including AP1, ELK/SRF, HIF1, and TCF/LEF, in SKOV3CR and OVCAR8CR cells. NA was further shown to effectively inhibit xenograft tumor growth of SKOV3CR cells. Collectively, our findings strongly suggest that NA may be repurposed as an efficacious agent to combat cisplatin resistance in chemoresistant human OC, and further clinical trials are highly warranted.

The role of proteasome inhibitor MG132 in cisplatin resistant ovarian cancer

Platinum based combined chemotherapy have been proved to be the most effective drugs for the ovarian cancer treatment, but it is difficult to treat cisplatin resistant ovarian cancer. Carbobenzoxy-L-leucy-L-Leucyl-L-Leucinal (MG132) is a reversible tripeptide aldehyde proteasome inhibitor, the purpose of this study was to observe the effect of MG132 on cisplatin resistant ovarian cancer SKOV3 cell and OVCAR-3 cell the expression of autophagy and apoptosis related factors. The cells were divided into four groups: control, MG132, cisplatin, MG132 and cisplatin combination groups. Cell growth was detected by cell counting kit-8 (CCK-8) assay. The apoptotic rates of cells and the cell cycle were detected by a flow cytometer (FCM). The Beclin1, Light chain 3 (LC3) and Caspase3 was detected by western blotting and reverse transcription-polymerase chain reaction (RT-PCR). Detection of apoptotic bodies by 4,6-Diamidino-2-phenylindole dihydrochloride (DAPI) staining. CCK-8 assay demonstrated that cell survival rate in the combination groups was lower than monotherapy group. FCM showed that apoptotic rates in the combination groups was higher than monotherapy group (p < 0.05). Western blotting and RT-PCR detected that Beclin1, LC3 and Caspase3 in the combination group were higher than monotherapy group (p < 0.05). DAPI staining showed the production of apoptotic bodies in the combination group and MG132 group. In conclusion, MG132 can inhibit the growth of cisplatin resistant ovarian cancer SKOV3 and OVCAR-3 cells, its inhibitory effect is related to apoptosis and autophagy, and it is expected to be a synergistic antitumor effect with cisplatin.

GBA inhibition suppresses ovarian cancer growth, survival and receptor tyrosine kinase AXL-mediated signaling pathways.

The poor outcome of advanced ovarian cancer under conventional therapy necessitates new strategies to improve therapeutic efficacy. β-glucosidase (encoded by GBA) is a lysosomal enzyme and is involved in sphingolipids metabolism. Recent studies revealed that β-glucosidase plays a role in cancer development and chemoresistance. In this work, we systematically evaluated the expression and role of GBA in ovarian cancer. Our work demonstrates that inhibition of β-glucosidase has therapeutic potential for ovarian cancer. Gene Expression Profiling Interactive Analysis database, western blot and immunohistochemistry analyses of patient samples demonstrated that GBA mRNA and protein expression levels were significantly increased in ovarian cancer compared to normal tissues. Functional studies using gain-of- function and loss-of-function approaches demonstrated that GBA overexpression did not affect growth and migration but alleviated cisplatin's efficacy in ovarian cancer cells. In addition, GBA depletion resulted in growth inhibition, apoptosis induction, and enhancement of cisplatin's efficacy. Of note, we found that GBA inhibition specifically decreased receptor tyrosine kinase AXL level, leading to the suppression of AXL-mediated signaling pathways. Our data suggest that GBA represents a promising target to inhibit AXL signaling and overcome cisplatin resistance in ovarian cancer.