DDP-resistant Ovarian Cancer Cells Research Articles

Silencing of NLRP3 Sensitizes Chemoresistant Ovarian Cancer Cells to Cisplatin.

Ovarian cancer is a fatal gynecological malignancy. The resistance to chemotherapy in ovarian cancer treatment has been a thorny issue. This study is aimed at probing the molecular mechanism of cisplatin (DDP) resistance in ovarian cancer. Bioinformatics analysis was conducted to examine the role of Nod-like receptor protein 3 (NLRP3) in ovarian cancer. The NLRP3 level in DDP-resistant ovarian cancer tumors and cell lines (SKOV3/DDP and A2780/DDP) was evaluated by applying immunohistochemical staining, western blot, and qRT-PCR. Cell transfection was conducted to regulate the NLRP3 level. Cell abilities to proliferate, migrate, invade, and apoptosis were measured employing colony formation, CCK-8, wound healing, transwell, and TUNEL assays, respectively. Cell cycle analysis was completed via flow cytometry. Corresponding protein expression was measured by western blot. NLRP3 was overexpressed in ovarian cancer, correlated with poor survival, and upregulated in DDP-resistant ovarian cancer tumors and cells. NLRP3 silencing exerted antiproliferative, antimigrative, anti-invasive, and proapoptotic effects in A2780/DDP and SKOV3/DDP cells. Additionally, NLRP3 silencing inactivated NLRPL3 inflammasome and blocked epithelial-mesenchymal transition via enhancing E-cadherin and lowering vimentin, N-cadherin, and fibronectin. NLRP3 was overexpressed in DDP-resistant ovarian cancer. NLRP3 knockdown hindered the malignant process of DDP-resistant ovarian cancer cells, providing a potential target for DPP-based ovarian cancer chemotherapy.

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.

Circ_0078607 increases platinum drug sensitivity via miR-196b-5p/GAS7 axis in ovarian cancer

ABSTRACT Platinum-based chemotherapy is one of the predominant strategies for treating ovarian cancer (OC), however, platinum resistance greatly influences the therapeutic effect. Circular RNAs (circRNAs) have been found to participate in the pathogenesis of platinum resistance. Our aim was to explore the involvement of circ_0078607 in OC cell cisplatin (DDP) resistance and its potential mechanisms. Circ_0078607, miR-196b-5p, and growth arrest-specific 7 (GAS7) levels were assessed by qPCR. Circ_0078607 stability was assessed by ribonuclease R digestion and actinomycin D treatment. Cell viability of various conic of DDP treatment was measured by CCK-8. The cell proliferation was determined by CCK-8 and colony formation assay. Western blotting was performed for determining GAS7, ABCB1, CyclinD1 and Bcl-2 protein levels. The direct binding between miR-196b-5p and circ_0078607 or GAS7 was validated by dual-luciferase reporter and RIP assay. DDP resistance in vivo was evaluated in nude mice. Immunohistochemistry staining for detecting Ki67 expression in xenograft tumours. Circ_0078607 and GAS7 was down-regulated, but miR-196b-5p was up-regulated in OC samples and DDP-resistant cells. Overexpression of circ_0078607 inhibited DDP resistance, cell growth and induced apoptosis in DDP-resistant OC cells. Mechanistically, circ_0078607 sequestered miR-196b-5p to up-regulate GAS7. MiR-196b-5p mimics reversed circ_0078607 or GAS7 overexpression-mediated enhanced sensitivity. Finally, circ_0078607 improved the sensitivity of DDP in vivo. Circ_0078607 attenuates DDP resistance via miR-196b-5p/GAS7 axis, which highlights the therapeutic potential of circ_0078607 to counter DDP resistance in OC.

Knockdown of circ-PIP5K1A overcomes resistance to cisplatin in ovarian cancer by miR-942-5p/NFIB axis.

Cisplatin (DDP)-based chemotherapy is the main chemotherapeutic agent for ovarian cancer (OC) treatment. Circular RNA PIP5K1A (circ-PIP5K1A) was found to promote OC tumorigenesis. However, whether circ-PIP5K1A was involved in DDP resistance in OC remains unclear. Levels of circ-PIP5K1A, microRNA (miR)-942-5p, and nuclear factor I B (NFIB) were detected using quantitative real-time PCR and Western blot assays. In-vitro experiments were conducted by using cell counting kit-8, cell colony formation, 5-ethynyl-2'-deoxyuridine, flow cytometry, and transwell assays, respectively. In-vivo assay was performed using murine xenograft model. The binding interaction between miR-942-5p and circ-PIP5K1A or NFIB was confirmed using dual-luciferase reporter assay. Exosomes were obtained from culture media by the use of commercial kits and qualified by transmission electron microscopy and Western blot. Circ-PIP5K1A was highly expressed in DDP-resistant OC tissues and cells. Circ-PIP5K1A knockdown could constrain the proliferation, migration, and invasion, as well as increase apoptosis and sensitivity to DDP in DDP-resistant OC cells. Mechanistically, circ-PIP5K1A acted as a sponge for miR-942-5p to positively regulate NFIB expression. Moreover, rescue experiments demonstrated that the anticancer and DDP sensitization effects caused by circ-PIP5K1A silencing in DDP-resistant OC cells were achieved through the miR-942-5p/NFIB axis. Importantly, circ-PIP5K1A silencing enhanced DDP efficacy and impeded tumor growth in OC in vivo . Additionally, we also found that circ-PIP5K1A was packaged into exosomes and could be internalized by surrounding cells. Circ-PIP5K1A knockdown reduced the resistance to DDP in OC via regulating miR-942-5p/NFIB axis. Besides that, circ-PIP5K1A was packaged into exosomes and exosomal circ-SKA3 could mediate intercellular communication between OC cells. These findings provided a promising therapeutic target for OC.

Circ_0007841 knockdown confers cisplatin sensitivity to ovarian cancer cells by down-regulation of NFIB expression in a miR-532-5p-dependent manner

ABSTRACT Cisplatin (DDP) is first-line management for ovarian cancer (OC). Previous data have suggested that circular RNA_0007841 (circ_0007841) regulates OC progression; however, there is no data on its role in the sensitivity of OC cells to DDP. RNA expression of circ_0007841, microRNA-532-5p (miR-532-5p) and nuclear factor I B (NFIB) was detected by quantitative real-time polymerase chain reaction in OC patient samples and OC cell lines. Protein expression was checked by Western blotting analysis. Cell viability, proliferation, cell apoptotic rate, migration and invasion were investigated by 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-diphenytetrazoliumromide, 5-Ethynyl-29-deoxyuridine, flow cytometry analysis, scratch test and transwell assays, respectively. The interactions among circ_0007841, miR-532-5p and NFIB were identified by a dual-luciferase reporter assay. Xenograft mouse model assay was performed to determine the effect of circ_0007841 on DDP sensitivity in vivo. Circ_0007841 and NFIB expression were upregulated, whereas miR-532-5p was downregulated in DDP-resistant OC tissues and cells compared with controls. Circ_0007841 silencing improved DDP sensitivity, inhibited cell proliferation, invasion and migration, but induced cell apoptosis in DDP-resistant OC cells. Circ_0007841 acted as a miR-532-5p sponge and regulated DDP resistance and OC cell malignancy through miR-532-5p in DDP-resistant OC cells. Besides, the overexpression of NFIB, a target of miR-532-5p, remitted miR-532-5p-mediated effects in DDP-resistant OC cells. Circ_0007841 depletion conferred DDP sensitivity to DDP-resistant OC cells in vivo. Further, circ_0007841 was secreted from DDP-resistant OC cells through being packaged into exosomes. Circ_0007841 conferred DDP resistance to DDP-resistant OC cells through the miR-532-5p/NFIB axis, suggesting the potential of circ_0007841 as a therapeutic target for OC.

RETRACTED ARTICLE: Protein tyrosine phosphatase receptor type Z1 inhibits the cisplatin resistance of ovarian cancer by regulating PI3K/AKT/mTOR signal pathway

Statement of Retraction Peng Wang, Yuanjing Hu, Pengpeng Qu, Ying Zhao, Jing Liu, Jianguo Zhao & Beihua Kong (2022) Protein tyrosine phosphatase receptor type Z1 inhibits the cisplatin resistance of ovarian cancer by regulating PI3K/AKT/mTOR signal pathway, Bioengineered, 13:1, 1931-1941, DOI: 10.1080/21655979.2021.2022268 Since publication, concerns have been raised about the integrity of the data in the article. When approached for an explanation, the authors have been unable to fully address the concerns raised and have not been able to provide their original data in the appropriate format. As verifying the validity of published work is core to the integrity of the scholarly record, we are therefore retracting the article. All authors listed in this publication have been informed. We have been informed in our decision-making by our editorial policies and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

Silencing of miR-1246 Induces Cell Cycle Arrest and Apoptosis in Cisplatin-Resistant Ovarian Cancer Cells by Promoting ZNF23 Transcription

Ovarian cancer (OC) is the most frequent cause of death among patients with gynecologic malignancies. In recent years, the development of cisplatin (DDP) resistance has become an important reason for the poor prognosis of OC patients. Therefore, it is vital to explore the mechanism of DDP resistance in OC. In this study, microRNA-1246 (miR-1246) expression in OC and DDP-resistant OC cells was determined by RT-qPCR, and chemosensitivity to DDP was assessed by the CCK-8 assay. A dual-luciferase reporter assay was performed to confirm the interaction between miR-1246 and zinc finger 23 (ZNF23), while changes in ZNF23 expression were monitored by RT-qPCR, immunofluorescence, and western blot assays. Moreover, cell proliferation, cycle phase, and apoptosis were determined by EdU staining, flow cytometry, TUNEL staining, and Hoechst staining. Our data showed that miR-1246 was highly expressed in DDP-resistant OVCAR-3 and TOV-112D cells. Functionally, overexpression of miR-1246 markedly enhanced DDP resistance and cell proliferation, and suppressed cell cycle arrest and apoptosis of OC cells. Inhibition of miR-1246 expression significantly attenuated DDP resistance and cell proliferation, and increased cell cycle arrest and apoptosis in DDP-resistant OC cells. Furthermore, ZNF23 was identified as a target gene of miR-1246, and ZNF23 protein expression was notably downregulated in DDP-resistant OC cells. Moreover, overexpression of miR-1246 significantly downregulated the ZNF23 levels in OVCAR-3 and TOV-112D cells, and inhibition of miR-1246 upregulated the ZNF23 levels in the DDP-resistant OVCAR-3 and TOV-112D cells. In conclusion, miR-1246 might be a novel regulator of DDP-resistant OC that functions by regulating ZNF23 expression in DDP-resistant cells, as well as cell proliferation, cell cycle progression, and apoptosis.

Circ_C20orf11 enhances DDP resistance by inhibiting miR-527/YWHAZ through the promotion of extracellular vesicle-mediated macrophage M2 polarization in ovarian cancer

ABSTRACT Ovarian cancer is a fatal gynecologic tumor, and conventional treatment is mainly limited by chemoresistance. The mechanism contributing to chemoresistance in ovarian cancer has yet to be established. This study aimed to investigate the specific role of circ_C20orf11 in regulating chemoresistance to cisplatin (DDP)in ovarian cancer. We first established two DDP-resistant ovarian cancer cell lines. Then, we identified the effect of circ_C20orf11 on specific cellular characteristics (proliferation, apoptosis, DDP resistance) via a series of experiments. The binding sites between circ_C20orf11 and miR-527 and between miR-527 and YWHAZ were predicted using a bioinformatics tool and confirmed with a dual-luciferase reporter assay. Furthermore, extracellular vesicles (EVs) derived from DDP-resistant cell lines were identified, and the effect of EVs on macrophage polarization was examined. circ_C20orf11 was upregulated in ovarian cancer. Increased circ_C20orf11 expression enhanced DDP resistance and cell proliferation and reduced cell apoptosis in DDP-resistant cell lines after DDP treatment by sponging miR-527 and promoting YWHAZ expression. In addition, we found that DDP-resistant cell-derived EVs can induce macrophage M2 polarization, whereas silencing of circ_C20orf11 inhibited EV-induced macrophage M2 polarization. Consistent with these results, silencing of circ_C20orf11 enhanced sensitivity to DDP in vivo. Importantly, we proved that circ_C20orf11 expression was upregulated in EVs extracted from the serum of DDP-resistant patients. Our study demonstrated that silencing circ_C20orf11 sensitizes ovarian cancer to DDP by promoting miR-527/YWHAZ signaling and EV-mediated macrophage M2 polarization.

CircHIPK2 Contributes to DDP Resistance and Malignant Behaviors of DDP-Resistant Ovarian Cancer Cells Both in vitro and in vivo Through circHIPK2/miR-338-3p/CHTOP ceRNA Pathway.

BackgroundCisplatin (DDP) is standard-of-care and first-line management for ovarian cancer (OvCa). Circular RNA HIPK2 (circHIPK2) is abnormally upregulated in serum of OvCa patients. However, its role in DDP resistance remains unclear.MethodsExpression of cirHIPK2, microRNA (miR)-338-3p and chromatin target of protein arginine methyltransferase (CHTOP) was detected by quantitative reverse transcription PCR and Western blotting. Functional experiments were performed using cell counting kit-8 assay, flow cytometry, transwell assays, Western blotting, and xenograft experiment. The interaction among cirHIPK2, miR-338-3p and CHTOP was confirmed by dual-luciferase reporter assay and RNA pull-down assay.ResultsExpression of circHIPK2 and CHTOP was upregulated, and miR-338-3p was downregulated in human DDP-resistant OvCa tumors and cells. Blocking circHIPK2 could promote apoptosis and suppress the 50% inhibitory concentration (IC50) of DDP, cell proliferation, cell cycle entrance, migration and invasion in SKOV3/DDP and A2780/DDP cells. Allied with that was decreased B cell lymphoma (Bcl)-2, matrix metalloproteinase 2 (MMP2) and MMP9 levels, and increased Bcl-2-associated X protein (Bax) level. Similarly, overexpression of miR-338-3p functioned suppressive role in SKOV3/DDP and A2780/DDP cells. MiR-338-3p was a target for circHIPK2, and CHTOP was targeted by miR-338-3p, whereas silencing miR-338-3p counteracted the role of circHIPK2 knockdown, and restoring CHTOP either cancelled miR-338-3p role. The growth of A2780/DDP cells in nude mice was restrained by silencing circHIPK2 under DDP treatment or not.ConclusionCircHIPK2 might be a tumor promoter in OvCa and was associated with DDP resistance. Silencing circHIPK2 might suppress DDP-resistant OvCa through regulating miR-338-3p/CHTOP axis.

FGFR3 phosphorylates EGFR to promote cisplatin-resistance in ovarian cancer

Ovarian cancer is a deadly gynecologic cancer, and the majority of patients with ovarian cancer experience relapse after traditional treatment. Cisplatin (DDP) is a common chemotherapeutic drug for ovarian cancer, but many patients acquire DDP-resistance after treatment with long-term chemotherapy. The mechanisms of drug-resistance in ovarian cancer are not clear, and we thus aim to investigate novel targets for DDP-resistant ovarian cancer. Differential analysis, KEGG pathway enrichment and protein interaction networks were employed to identify the key genes related to DDP-resistance in ovarian cancer. Subsequently, cell viability, apoptosis and migration were measured to assess the effect of fibroblast growth factor receptor 3 (FGFR3) on DDP-resistance. Further, Pearson correlation analysis and co-expression analysis were used to explore the downstream pathways of FGFR3, and the function of FGFR3 and its downstream targets were further demonstrated by in vitro and nude mice experiments. FGFR3 were expressed at high levels in DDP-resistant ovarian cancer cells. FGFR3 silencing suppressed the activation of PI3K/AKT pathway and impeded the drug-resistance and development of tumor cells. Afterwards, we found that FGFR3 was co-expressed with epidermal growth factor receptor (EGFR). FGFR3 overexpression elevated EGFR phosphorylation and activated PI3K/AKT signaling. Furthermore, in nude mice, silencing FGFR3 and inhibiting EGFR phosphorylation were observed to promote the therapeutic effect of DDP. In conclusion, FGFR3 overexpression enhances DDP-resistance of ovarian cancer by promoting EGFR phosphorylation and further activating PI3K/AKT pathway. This study may offer promising targets for DDP-resistant ovarian cancer.

LncRNA MALAT1 Regulates the Progression and Cisplatin Resistance of Ovarian Cancer Cells via Modulating miR-1271-5p/E2F5 Axis.

BackgroundLong non-coding RNAs (lncRNAs) and microRNAs (miRNAs) were reported to be related to the development of ovarian cancer (OC). In this study, the functional mechanisms of lncRNA metastasis associated with lung adenocarcinoma transcript 1 (MALAT1) and microRNA-1271-5p (miR-1271-5p) were explored in OC.MethodsThe level of MALAT1, miR-1271-5p, or E2F transcription factor 5 (E2F5) was detected by qRT-PCR. MTT assay, flow cytometry analysis and transwell migration and invasion assays were performed to determine cell proliferation, apoptosis, migration and invasion, respectively. E2F5 protein expression was detected by Western blot. The interaction between miR-1271-5p and MALAT1 or E2F transcription factor 5 (E2F5) was confirmed by the dual-luciferase reporter assay.ResultsMALAT1 and E2F5 level were increased, while miR-1271-5p level was decreased in cisplatin (DDP)-resistant OC tissues and cells. MALAT1 knockdown or miR-1271-5p upregulation decreased IC50 of cisplatin, and inhibited cell proliferation, migration, invasion, and facilitated cell apoptosis in DDP-resistant OC cells. Moreover, MALAT1 sponged miR-1271-5p to upregulate E2F5 expression. Besides, MALAT1 knockdown decreased DDP resistance, inhibited cell proliferation, migration, invasion, and promoted cell apoptosis by sponging miR-1271-5p to downregulate E2F5 expression in DDP-resistant OC cell.ConclusionWe demonstrated that MALAT1 mediated DDP-resistant OC development through miR-1271-5p/E2F5 axis, providing the theoretical basis for OC therapy.

Nanoparticle BAF312@CaP-NP Overcomes Sphingosine-1-Phosphate Receptor-1-Mediated Chemoresistance Through Inhibiting S1PR1/P-STAT3 Axis in Ovarian Carcinoma.

PurposePlatinum/paclitaxel-based chemotherapy is the strategy for ovarian cancer, but chemoresistance, inherent or acquired, occurs and hinders therapy. Therefore, further understanding of the mechanisms of drug resistance and adoption of novel therapeutic strategies are urgently needed.MethodsIn this study, we report that sphingosine-1-phosphate receptor-1 (S1PR1)-mediated chemoresistance for ovarian cancer. Then we developed nanoparticles with a hydrophilic PEG2000 chain and a hydrophobic DSPE and biodegradable CaP (calcium ions and phosphate ions) shell with pH sensitivity as a delivery system (CaP-NPs) to carry BAF312, a selective antagonist of S1PR1 (BAF312@CaP-NPs), to overcome the cisplatin (DDP) resistance of the ovarian cancer cell line SKOV3DR.ResultsWe found that S1PR1 affected acquired chemoresistance in ovarian cancer by increasing the phosphorylated-signal transduction and activators of transcription 3 (P-STAT3) level. The mean size and zeta potential of BAF312@CaP-NPs were 116 ± 4.341 nm and −9.67 ± 0.935 mV, respectively. The incorporation efficiency for BAF312 in the CaP-NPs was 76.1%. The small size of the nanoparticles elevated their enrichment in the tumor, and the degradable CaP shell with smart pH sensitivity of the BAF312@CaP-NPs ensured the release of BAF312 in the acidic tumor niche. BAF312@CaP-NPs caused substantial cytotoxicity in DDP-resistant ovarian cancer cells by downregulating S1PR1 and P-STAT3 levels.ConclusionWe found that BAF312@CaP-NPs act as an effective and selective delivery system for overcoming S1PR1-mediated chemoresistance in ovarian carcinoma by inhibiting S1PR1 and P-STAT3.

Knockdown of long non-coding RNA HOTAIR reverses cisplatin resistance of ovarian cancer cells through inhibiting miR-138-5p-regulated EZH2 and SIRT1

BackgroundCisplatin resistance (DDP-resistance) remains one of the major causes of poor prognosis in females with ovarian cancer. Long non-coding RNAs (lncRNAs) have been shown to participate in the regulation of cellular processes, including chemoresistance. The aim of this study was to explore the role of HOX transcript antisense RNA (HOTAIR) in DDP-resistant ovarian cancer cells.MethodsDDP-resistant ovarian cancer cell lines (SKOV3/DDP and A2780/DDP) were established. Real-time PCR, western blot, dual-luciferase reporter assay, and flow cytometry were then used to evaluate the effect of HOTAIR/miR-138-5p axis on chemoresistance of DDP-resistant ovarian cancer cells to DDP.ResultsWe found that HOTAIR was upregulated in DDP-resistant cells, while miR-138-5p was downregulated. Knockdown of HOTAIR increased the expression of miR-138-5p in DDP-resistant cells and miR-138-5p is directly bound to HOTAIR. Upregulation of miR-138-5p induced by HOTAIR siRNA or by its mimics enhanced the chemosensitivity of DDP-resistant cells and decreased the expression of EZH2 (enhancer of zeste 2 polycomb repressive complex 2 subunit) and SIRT1 (sirtuin 1). Furthermore, the HOTAIR silencing-induced chemosensitivity of DDP-resistant cells was weakened by miR-138-5p inhibitor.ConclusionsThese data demonstrate that HOTAIR acts as a sponge of miR-138-5p to prevent its binding to EZH2 and SIRT1, thereby promoting DDP-resistance of ovarian cancer cells. Our work will shed light on the development of therapeutic strategies for ovarian cancer treatment.

Mitochondria-targeting zeolitic imidazole frameworks to overcome platinum-resistant ovarian cancer

Epithelial ovarian cancer is still the leading cause of death in gynecology due to its resistance to platinum-based first-line chemotherapeutic drugs. The utilization of mitochondria-targeted drugs has become an important direction in anti-tumor drug research and development. In this work, cisplatin (DDP)-loaded ZIF-90 with mitochondrial-targeting was synthesized at room temperature with a high drug loading (11.7 %, calculated based on Pt content). The ZIF-90@DDP showed high cellular uptake and less toxicity in both non- and DDP-resistant ovarian cancer cells with effective pH- and ATP-responsive drug release. Both mitochondria-targeting and responsive drug release could increase the drug concentration in mitochondria of drug-resistant cancer cells to reverse such resistance. Conclusively, the mitochondria-targeting ZIF-90@DDP with high drug loading could trigger responsive drug release in mitochondria of epithelial ovarian cancer cells, inhibit DPP-resistant epithelial ovarian cancer cells, and reverse drug resistance.

MiR-34a-5p/PD-L1 axis regulates cisplatin chemoresistance of ovarian cancer cells.

Ovarian cancer is the most lethal gynecologic malignancy in women with an increasing number of cases worldwide. Chemoresistance is the main obstacle for ovarian cancer treatment during clinical therapy. Previous studies found that programmed cell death 1 ligand 1 (PD-L1) was associated with chemoresistance of cancer. However, there were little reports about the function of PD-L1 involved in chemoresistance of ovarian cancer. In our study, cisplatin (DDP)-resistant SKOV3 and A2780 ovarian cancer cell lines (SKOV3/DDP and A2780/DDP) were established. We found that the expression of PD-L1 was increased and miR-34a-5p was decreased in DDP-resistant cells. PD-L1 silencing inhibited chemoresistance of DDP-resistant ovarian cancer cells to DDP, as evidenced by decreased proliferation, G1-phase cell cycle arrest and increased apoptosis. Western blot assay showed that in the presence of DDP, PD-L1 silencing decreased multidrug resistance protein 1 and Cyclin D1 protein levels, whereas increased cleaved-caspase-3 and cleaved-PARP protein levels in these cells. Moreover, we demonstrated that miR-34a-5p negatively regulated the expression of PD-L1 by targeting its 3'-untranslated region. The effects of miR-34a-5p mimic on DDP-treated SKOV3/DDP cells were reversed by the overexpression of PD-L1. Moreover, the tumorigenicity of DDP-resistant ovarian cancer cells in nude mice treated with DDP was attenuated by miR-34a-5p in vivo. The combined data indicate that miR-34a-5p/PD-L1 axis regulates DDP chemoresistance of ovarian cancer cells, providing a deeper insight into the treatment for ovarian cancer.

RCC2, a regulator of the RalA signaling pathway, is identified as a novel therapeutic target in cisplatin-resistant ovarian cancer.

Currently, cisplatin (DDP) is the first-line chemotherapeutic agent used for treatment of ovarian cancer, but gradually acquired drug resistance minimizes its therapeutic outcomes. We aimed to identify crucial genes associated with DDP resistance in ovarian cancer and uncover potential mechanisms. Two sets of gene expression data were downloaded from Gene Expression Omnibus, and bioinformatics analysis was conducted. In our study, the differentially expressed genes between DDP-sensitive and DDP-resistant ovarian cancer were screened in GSE15709 and GSE51373 database, and chromosome condensation 2 regulator (RCC2) and nucleoporin 160 were identified as 2 genes that significantly up-regulated in DDP-resistant ovarian cancer cell lines compared with DDP-sensitive cell lines. Moreover, RCC2, Ral small GTPase (RalA), and Ral binding protein-1 (RalBP1) expression was found to be significantly higher in DDP-resistant ovarian cancer tissues than in DDP-sensitive tissues. RCC2 plays a positive role in cell proliferation, apoptosis, and migration in DDP-resistant ovarian cancer cell lines in vitro and in vivo. Furthermore, RCC2 could interact with RalA, thus promoting its downstream effector RalBP1. RalA knockdown could reverse the effects of RCC2 overexpression on DDP-resistant ovarian cancer cell proliferation, apoptosis, and migration. Similarly, RalA overexpression could alleviate the effects of RCC2 knockdown in DDP-resistant ovarian cancer cells. Taken together, RCC2 may function as an oncogene, regulating the RalA signaling pathway, and intervention of RCC2 expression might be a promising therapeutic strategy for DDP-resistant ovarian cancer.-Gong, S., Chen, Y., Meng, F., Zhang, Y., Wu, H., Li, C., Zhang, G. RCC2, a regulator of the RalA signaling pathway, is identified as a novel therapeutic target in cisplatin-resistant ovarian cancer.

Roflumilast enhances cisplatin-sensitivity and reverses cisplatin-resistance of ovarian cancer cells via cAMP/PKA/CREB-FtMt signalling axis.

We previously demonstrated the roflumilast inhibited cell proliferation and increased cell apoptosis in ovarian cancer. In this study, we aimed to investigate the roles of roflumilast in development of cisplatin (DDP)-sensitive and -resistant ovarian cancer. OVCAR3 and SKOV3 were selected and the corresponding DDP-resistant cells were constructed. Cell viability, proliferation, apoptosis, cycle were performed. Expression cAMP, PKA, CREB, phosphorylation of CREB and FtMt were detected. The roles of roflumilast in development of DDP-sensitive and -resistant ovarian cancer were confirmed by xenograft model. Roflumilast+DDP inhibited cell proliferation, and induced cell apoptosis and G0/G1 arrest in OVCAR3 and SKOV3 cells, roflumilast induced expression of FtMt, the activity of cAMP and PKA and phosphorylation of CREB in ovarian cancer cells and the above-effect were inhibited by H89. Downregulation of CREB inhibited the roflumilast-increased DDP sensitivity of ovarian cancer cells, and the roflumilast-induced FtMt expression and phosphorylation of CREB. Also, roflumilast reversed cisplatin-resistance, and induced expression of FtMt and activation of cAMP/PKA/CREB in DDP-resistant ovarian cancer cells. Similarly, treated with H89 or downregulation of CREB inhibited the changes induced by roflumilast. In vivo, roflumilast inhibited the development of SKOV3 or SKOV3-DDP-R xenograft models. Roflumilast enhanced DDP sensitivity and reversed the DDP resistance of ovarian cancer cells via activation of cAMP/PKA/CREB pathway and upregulation of the downstream FtMt expression, which has great promise in clinical treatment.

PD98059 impairs the cisplatin-resistance of ovarian cancer cells by suppressing ERK pathway and epithelial mesenchymal transition process.

The study was aimed at investigating the role of PD98059 on impairing the cisplatin-resistance of ovarian cancer cells and figuring out the potential mechanism. Treated with low dose of cisplatin (DDP), DDP-resistant ovarian cancer cells were built and named as SKOV-3/DDP. The cell viabilities of ovarian cancer cell line SKOV-3 and SKOV-3/DDP were detected using MTT assay. Wound healing assay and flow cytometry were performed to detect the migratory ability and cell cycle variation of the two cells and assess the sensibility to DDP in the two cell lines. However, cotreated with DDP and PD98059, cell viability, migration and cell cycle of SKOV-3/DDP were determined again. The DDP-resistance varied a lot and the potential mechanism was studied via western blot assay. Both treated with DDP, SKOV-3/DDP showed an intense resistance than SKOV-3 including stronger cell viability, larger migration area and less G1/G0 arrest, which confirmed the successfully established DDP-resistant cell line. The phosphorylation of ERK and the activation of epithelial mesenchymal transition (EMT) process contributes to the enhanced resistance. PD98059, a MEK inhibitor, suppresses the ERK pathway and the EMT process of SKOV-3/DDP. Co-treated by DDP and PD98059, cell proliferation and migratory area decreased, meantime more cell were arrested in G0/G1 phase compared to simple treatment of DDP or PD98059. PD98059 efficiently impairs the DDP-resistance of ovarian cancer cells via downregulating the ERK pathway and the EMT process.

Low-dose radiation enhances susceptibility to cisplatin in resistant ovarian cancer cells via downregulation of ERCC1 and Bcl-2

Abstract Objective Ovarian cancer is one of the leading causes of mortality in patients with malignant gynecological tumors. After surgical intervention for ovarian cancer, cisplatin (DDP)-based chemotherapy is the first-line treatment. However, a major challenge to treating ovarian cancer is the development of chemoresistance. Thus, the first aim of this study was to determine whether low-dose radiation could enhance the susceptibility of resistant ovarian cancer cells to DDP. The second aim was to provide new strategies for treating DDP-resistant ovarian cancer by examining its mechanism. Methods A cell counting kit-8 (CCK8) assay was performed to measure cell proliferation. Flow cytometry was utilized to quantify the apoptosis of DDP-resistant ovarian cancer cells (SKOV3/DDP) using Annexin V and propidium iodide staining. Real-time quantitative (qPCR) was used to analyze the messenger RNA (mRNA) expression levels of excision repair cross complementing-group 1 (ERCC1) and B-cell lymphoma 2 (Bcl-2) in SKOV3/DDP. Results The IC50 values of the control, conventional-dose, and low-dose groups were 9.367 ± 0.16, 9.289 ± 0.16, and 3.847 ± 0.15, respectively (P < 0.05 vs control group and conventional-dose group). Compared with the control and conventional-dose groups, low-dose radiation resulted in significantly more apoptosis, as detected by flow cytometry (P < 0.05). The relative mRNA expression of ERCC1 and Bcl-2 in the low-dose group was significantly lower than that in the control group and conventional-dose group (P < 0.05). Conclusion Low-dose radiation enhanced the sensitivity of resistant ovarian cancer cells to DDP, possibly by decreasing the DNA repair capacity of tumor cells and promoting apoptosis.