Paclitaxel-resistant Ovarian Cancer Research Articles

Alkaliptosis induction counteracts paclitaxel-resistant ovarian cancer cells via ATP6V0D1-mediated ABCB1 inhibition.

Paclitaxel serves as the cornerstone chemotherapy for ovarian cancer, yet its prolonged administration frequently culminates in drug resistance, presenting a substantial challenge. Here we reported that inducing alkaliptosis, rather than apoptosis or ferroptosis, effectively overcomes paclitaxel resistance. Mechanistically, ATPase H+ transporting V0 subunit D1 (ATP6V0D1), a key regulator of alkaliptosis, plays a pivotal role by mediating the downregulation of ATP-binding cassette subfamily B member 1 (ABCB1), a multidrug resistance protein. Both ATP6V0D1 overexpression through gene transfection and pharmacological enhancement of ATP6V0D1 protein stability using JTC801 effectively inhibit ABCB1 upregulation, resulting in growth inhibition in drug-resistant cells. Additionally, increasing intracellular pH to alkaline (pH 8.5) via sodium hydroxide application suppresses ABCB1 expression, whereas reducing the pH to acidic conditions (pH 6.5) with hydrochloric acid amplifies ABCB1 expression in drug-resistant cells. Collectively, these results indicate a potentially effective therapeutic strategy for targeting paclitaxel-resistant ovarian cancer by inducing ATP6V0D1-dependent alkaliptosis.

Classification of paclitaxel-resistant ovarian cancer cells using holographic flow cytometry through interpretable machine learning

Progress has been made in chemotherapy drugs, but drug resistance remains a major challenge in cancer treatment. In clinical practice, although there are existing technologies to assess chemotherapy resistance, there is still a lack of rapid and convenient method to monitor different degrees of drug resistance in cancer cells. Furthermore, the cell morphological changes during the progression of drug resistance remain to be fully understood. In this study, we employed a flow imaging platform based on digital holography (DH) and machine learning to classify cancer cells with different degrees of paclitaxel sensitivity. We extracted 112 morphological features from four datasets of single-cell quantitative phase images of epithelial ovarian cancer (EOC) cells and performed classification training using five supervised machine learning algorithms. Both support vector machine (SVM) and neural network (NN) achieved over 90% classification accuracy. To understand the morphological features associated with drug resistance properties of cancer cells, we applied the SHapley Additive exPlanations (SHAP), a model interpretation framework, to quantify and rank the feature contributions for both classification models. The results reported here about this label-free and high-accuracy assessment of different degrees of drug resistance in cancer cells opens the route to exploitation for monitoring chemotherapy in clinic practices.

Targeting PNPO to suppress tumor growth via inhibiting autophagic flux and to reverse paclitaxel resistance in ovarian cancer.

Our previous study showed that pyridoxine 5'-phosphate oxidase (PNPO) is a tissue biomarker of ovarian cancer (OC) and has a prognostic implication but detailed mechanisms remain unclear. The current study focused on PNPO-regulated lysosome/autophagy-mediated cellular processes and the potential role of PNPO in chemoresistance. We found that PNPO was overexpressed in OC cells and was a prognostic factor in OC patients. PNPO significantly promoted cell proliferation via the regulation of cyclin B1 and phosphorylated CDK1 and shortened the G2M phase in a cell cycle. Overexpressed PNPO enhanced the biogenesis and perinuclear distribution of lysosomes, promoting the degradation of autophagosomes and boosting the autophagic flux. Further, an autolysosome marker LAMP2 was upregulated in OC cells. Silencing LAMP2 suppressed cell growth and induced cell apoptosis. LAMP2-siRNA blocked PNPO action in OC cells, indicating that the function of PNPO on cellular processes was mediated by LAMP2. These data suggest the existence of the PNPO-LAMP2 axis. Moreover, silencing PNPO suppressed xenographic tumor formation. Chloroquine counteracted the promotion effect of PNPO on autophagic flux and inhibited OC cell survival, facilitating the inhibitory effect of PNPO-shRNA on tumor growth in vivo. Finally, PNPO was overexpressed in paclitaxel-resistant OC cells. PNPO-siRNA enhanced paclitaxel sensitivity in vitro and in vivo. In conclusion, PNPO has a regulatory effect on lysosomal biogenesis that in turn promotes autophagic flux, leading to OC cell proliferation, and tumor formation, and is a paclitaxel-resistant factor. These data imply a potential application by targeting PNPO to suppress tumor growth and reverse PTX resistance in OC.

Abstract 7139: Anti-cancer effects of benzimidazole derivative BNZ-111 on paclitaxel-resistant ovarian cancer

Abstract Ovarian cancer, a leading cause of cancer-related deaths in women, remains a formidable challenge, especially in the context of platinum-resistant disease. This study investigated the potential of the benzimidazole derivative BNZ-111 as a novel treatment strategy for platinum-resistant ovarian cancer. With improved pharmacokinetic parameters, BNZ-111 effectively disrupts tubulin polymerization through hydrogen bonds and hydrophobic interactions. It demonstrated strong cytotoxicity in both chemo-sensitive and chemo-resistant epithelial ovarian cancer cell lines, inducing apoptosis and G2/M cell cycle arrest. In vivo experiments using orthotopic and patient-derived xenograft models showed significant tumor growth inhibition without apparent toxicity to vital organs. Unlike paclitaxel, BNZ-111 proved effective in paclitaxel-resistant cells, potentially by bypassing interaction with MDR1 and modulating β-3 tubulin expression to suppress microtubule dynamics. This study suggests that BNZ-111, with favorable drug-like properties, holds promise as a therapeutic option for platinum-resistant ovarian cancer, addressing a critical clinical need in gynecologic oncology Citation Format: Jeong-Won Lee, Kwangho Lee, Byumseok Koh, Yoo-Young Lee, Duk-Soo Bae. Anti-cancer effects of benzimidazole derivative BNZ-111 on paclitaxel-resistant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7139.

WP1066, a small molecule inhibitor of STAT3, chemosensitizes paclitaxel-resistant ovarian cancer cells to paclitaxel by simultaneously inhibiting the activity of STAT3 and the interaction of STAT3 with Stathmin

Paclitaxel is widely used to treat cancer, however, drug resistance limits its clinical utility. STAT3 is constitutively activated in some cancers, and contributes to chemotherapy resistance. Currently, several STAT3 inhibitors including WP1066 are used in cancer clinical trials. However, whether WP1066 reverses paclitaxel resistance and the mechanismremains unknown. Here, we report that in contrast to paclitaxel-sensitive parental cells, the expressions of several pro-survival BCL2 family members such as BCL-2, BCL-XL and MCL-1 are higher in paclitaxel-resistant ovarian cancer cells. Meanwhile, STAT3 is constitutively activated while stathmin loses its activity in paclitaxel-resistant cells. Importantly, WP1066 amplifies the inhibition of cell proliferation, colony-forming ability and apoptosis of ovarian cancer cells induced by paclitaxel. Mechanistically, WP1066, on the one hand, interferes the STAT3/Stathmin interaction, causing unleash of STAT3/Stathmin from microtubule, thus destroying microtubule stability. This process results in reduction of Ac-α-tubulin, further causing MCL-1 reduction. On the other hand, WP1066 inhibits phosphorylation of STAT3 by JAK2, and blocks its nuclear translocation, therefore repressing the transcription of pro-survival targets such as BCL-2, BCL-XL and MCL-1. Finally, the two pathways jointly promote cell death. Our findings reveal a new mechanism wherein WP1066 reverses paclitaxel-resistance of ovarian cancer cells by dually inhibiting STAT3 activity and STAT3/Stathmin interaction, which may layfoundation for WP1066 combined with paclitaxel in treating paclitaxel-resistant ovarian cancer.

Pan-EGFR Inhibitor Dacomitinib Resensitizes Paclitaxel and Induces Apoptosis via Elevating Intracellular ROS Levels in Ovarian Cancer SKOV3-TR Cells.

Paclitaxel is still used as a standard first-line treatment for ovarian cancer. Although paclitaxel is effective for many types of cancer, the emergence of chemoresistant cells represents a major challenge in chemotherapy. Our study aimed to analyze the cellular mechanism of dacomitinib, a pan-epidermal growth factor receptor (EGFR) inhibitor, which resensitized paclitaxel and induced cell cytotoxicity in paclitaxel-resistant ovarian cancer SKOV3-TR cells. We investigated the significant reduction in cell viability cotreated with dacomitinib and paclitaxel by WST-1 assay and flow cytometry analysis. Dacomitinib inhibited EGFR family proteins, including EGFR and HER2, as well as its downstream signaling proteins, including AKT, STAT3, ERK, and p38. In addition, dacomitinib inhibited the phosphorylation of Bad, and combination treatment with paclitaxel effectively suppressed the expression of Mcl-1. A 2'-7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay revealed a substantial elevation in cellular reactive oxygen species (ROS) levels in SKOV3-TR cells cotreated with dacomitinib and paclitaxel, which subsequently mediated cell cytotoxicity. Additionally, we confirmed that dacomitinib inhibits chemoresistance in paclitaxel-resistant ovarian cancer HeyA8-MDR cells. Collectively, our research indicated that dacomitinib effectively resensitized paclitaxel in SKOV3-TR cells by inhibiting EGFR signaling and elevating intracellular ROS levels.

Tephrosin Suppresses the Chemoresistance of Paclitaxel-Resistant Ovarian Cancer via Inhibition of FGFR1 Signaling Pathway.

Ovarian cancer is the leading cause of death among gynecologic cancers. Paclitaxel is used as a standard first-line therapeutic agent for ovarian cancer. However, chemotherapeutic resistance and high recurrence rates are major obstacles to treating ovarian cancer. We have found that tephrosin, a natural rotenoid isoflavonoid, can resensitize paclitaxel-resistant ovarian cancer cells to paclitaxel. Cell viability, immunoblotting, and a flow cytometric analysis showed that a combination treatment made up of paclitaxel and tephrosin induced apoptotic death. Tephrosin inhibited the phosphorylation of AKT, STAT3, ERK, and p38 MAPK, all of which simultaneously play important roles in survival signaling pathways. Notably, tephrosin downregulated the phosphorylation of FGFR1 and its specific adapter protein FRS2, but it had no effect on the phosphorylation of the EGFR. Immunoblotting and a fluo-3 acetoxymethyl assay showed that tephrosin did not affect the expression or function of P-glycoprotein. Additionally, treatment with N-acetylcysteine did not restore cell cytotoxicity caused by a treatment combination made up of paclitaxel and tephrosin, showing that tephrosin did not affect the reactive oxygen species scavenging pathway. Interestingly, tephrosin reduced the expression of the anti-apoptotic factor XIAP. This study demonstrates that tephrosin is a potent antitumor agent that can be used in the treatment of paclitaxel-resistant ovarian cancer via the inhibition of the FGFR1 signaling pathway.

Resensitizing Paclitaxel-Resistant Ovarian Cancer via Targeting Lipid Metabolism Key Enzymes CPT1A, SCD and FASN.

Epithelial ovarian cancer (EOC) is a lethal gynecological cancer, of which paclitaxel resistance is the major factor limiting treatment outcomes, and identification of paclitaxel resistance-related genes is arduous. We obtained transcriptomic data from seven paclitaxel-resistant ovarian cancer cell lines and corresponding sensitive cell lines. Define genes significantly up-regulated in at least three resistant cell lines, meanwhile they did not down-regulate in the other resistant cell lines as candidate genes. Candidate genes were then ranked according to the frequencies of significant up-regulation in resistant cell lines, defining genes with the highest rankings as paclitaxel resistance-related genes (PRGs). Patients were grouped based on the median expression of PRGs. The lipid metabolism-related gene set and the oncological gene set were established and took intersections with genes co-upregulated with PRGs, obtaining 229 co-upregulated genes associated with lipid metabolism and tumorigenesis. The PPI network obtained 19 highly confidential synergistic targets (interaction score > 0.7) that directly associated with CPT1A. Finally, FASN and SCD were up-stream substrate provider and competitor of CPT1A, respectively. Western blot and qRT-PCR results confirmed the over-expression of CPT1A, SCD and FASN in the A2780/PTX cell line. The inhibition of CPT1A, SCD and FASN down-regulated cell viability and migration, pharmacological blockade of CPT1A and SCD increased apoptosis rate and paclitaxel sensitivity of A2780/PTX. In summary, our novel bioinformatic methods can overcome difficulties in drug resistance evaluation, providing promising therapeutical strategies for paclitaxel-resistant EOC via taregting lipid metabolism-related enzymes.

RSK4 confers paclitaxel resistance to ovarian cancer cells, which is resensitized by its inhibitor BI-D1870

Many ovarian cancers initially respond well to chemotherapy, but often become drug-resistant after several years. Therefore, analysis of drug resistance mechanisms and overcoming resistance are urgently needed. Paclitaxel is one of the first-choice and widely-used drugs for ovarian cancer, but like most drugs, drug resistance is observed in subsequent use. RSK4 is known as a tumor-suppressor, however, it has increasingly been reported to lead to drug resistance. Here, we found that RSK4 expression was elevated in paclitaxel-resistant ovarian cancer cells using DNA microarray, quantitative real-time PCR, and western blotting analysis. We examined the contribution of RSK4 to paclitaxel resistance and found that paclitaxel sensitivity was restored by RSK inhibitor co-treatment. We analyzed the mechanism by which resistance is developed when RSK4 level is elevated, and accelerated phosphorylation of the downstream translation factor eIF4B was discovered. In the Kaplan-Meier plot, the overall survival time was longer with RSK4 high, supporting its role as a tumor suppressor, as in previous findings, but the tendency was reversed when focusing on paclitaxel treatment. In addition, RSK4 levels were higher in non-responders than in responders in the ROC plotter. Finally, external expression of RSK4 in ovarian cancer cells increased the cell viability under paclitaxel treatment. These findings suggest that RSK4 may contribute to paclitaxel resistance, and that co-treatment with RSK4 inhibitors is effective treatment of paclitaxel-resistant ovarian cancer in which RSK4 is elevated.

CircSLC39A8 attenuates paclitaxel resistance in ovarian cancer by regulating the miR‑185‑5p/BMF axis

Chemoresistance to paclitaxel (PTX) is one of the main reasons for treatment failure and poor prognosis in patients with advanced ovarian cancer. Therefore, it is imperative to explore the mechanisms related to chemotherapy resistance in ovarian cancer to find potential therapeutic targets. Circular RNAs (circRNAs) play important roles in cancer development and progression. However, their biological functions and clinical significance in ovarian cancer have not been fully elucidated. Therefore, in this study, we aimed to investigate the function and underlying mechanism of hsa_circ_0002782 (circSLC39A8), identified by circRNA sequencing, in regulating PTX resistance. The effects of circSLC39A8 on PTX resistance was assessed by cell viability, colony formation, flow cytometry assays and an in vivo subcutaneous xenografted tumor mouse model. RNA immunoprecipitation and dual-luciferase reporter assays were performed to verify the interaction between circSLC39A8 and the miR-185–5p/BMF signal axis. We found that circSLC39A8 was downregulated in PTX-resistant ovarian cancer cells and tissues, and its low expression was associated with poor prognosis. Biologically, circSLC39A8 knockdown promoted PTX resistance in vitro and in vivo, while circSLC39A8 overexpression showed the opposite effect. Mechanistically, circSLC39A8, acting as an endogenous sponge for miR-185–5p, could relieve the inhibition of miR-185–5p on the expression of its downstream target, BMF; thus enhancing the sensitivity of ovarian cancer to PTX. Our findings demonstrate that circSLC39A8 can promote PTX sensitivity by regulating the miR-185–5p/BMF axis. This may be a valuable prognostic biomarker and a promising therapeutic target for patients with ovarian cancer.

Curcumin reduces paclitaxel resistance in ovarian carcinoma cells by upregulating SNIP1 and inhibiting NFκB activity

The therapeutic activity of paclitaxel against ovarian carcinoma is relatively low due to the frequent occurrence of chemoresistance and disease recurrence. We found earlier that a combination of curcumin and paclitaxel reduces cell viability and promotes apoptosis in paclitaxel-resistant (i.e., taxol-resistant, Txr) ovarian cancer cells. In the present study, we first used RNA sequencing (RNAseq) analysis to identify genes that are upregulated in Txr cell lines but downregulated by curcumin in ovarian cancer cells. The nuclear factor kappa B (NFκB) signaling pathway was shown to be upregulated in Txr cells. Furthermore, based on the protein interaction database BioGRID, we found that Smad nuclear interacting protein 1 (SNIP1) may be involved in regulating the activity of NFκB in Txr cells. Accordingly, curcumin upregulated SNIP1 expression, which in turn downregulated the pro-survival genes Bcl-2 and Mcl-1. Using shRNA-guided gene silencing, we found that SNIP1 depletion reversed the inhibitory effect of curcumin on NFκB activity. Moreover, we identified that SNIP1 enhanced NFκB protein degradation, thereby suppressing NFκB/p65 acetylation, which is involved in the inhibitory effect of curcumin on NFκB signaling. The transcription factor early growth response protein 1 (EGR1) was shown to represent an upstream transactivator of SNIP1. Consequently, we show that curcumin inhibits NFκB activity by modulating the EGR1/SNIP1 axis to attenuate p65 acetylation and protein stability in Txr cells. These findings provide a new mechanism to account for the effects of curcumin in inducing apoptosis and reducing paclitaxel resistance in ovarian cancer cells.

A novel micellar carrier to reverse multidrug resistance of tumours: TPGS derivatives with end-grafted cholesterol

D-α-tocopherol polyethylene glycol succinate (TPGS) has good biocompatibility, low immunogenicity, prolonged circulation time, and it can reverse multidrug resistance of tumours. However, the micelle concentration (CMC) of TPGS is too high (0.2 mg/mL) to develop the formulation of the micelle. In this study, TPGS was modified with cholesterol to obtain a new carrier material, TPGS-CHMC. The CMC of TPGS-CHMC was 2 μg/mL, which was extremely lower than that of TPGS. Docetaxel (DTX)-loaded TPGS-CHMC micelles (TPGS-CHMC/DTX) exhibited an average size of approximately 13 nm, a zeta potential of approximately −4.66 mV, and high encapsulation efficiency (99.2 ± 0.6%). TPGS-CHMC reduced mitochondrial membrane potential and cell membrane fluidity in paclitaxel-resistant ovarian cancer cells (A2780/T). In vivo, DiR-loaded TPGS-CHMC micelles were selectively distributed in A2780/T tumour-bearing nude mice. In A2780/T tumour-bearing nude mice, TPGS-CHMC/DTX micelles displayed significantly higher anti-tumour activity and less toxicity than the free DTX solution. In summary, TPGS-CHMC has various advantages and provides a new option for developing functional polymeric micelles.

MiR-92a regulates PTEN/Akt signaling axis to promote paclitaxel resistance in ovarian cancer cells.

To investigate the function and possible mechanism of miR-92a in malignant behaviors such as paclitaxel resistance in ovarian cancer (OC) cells. The miR-92a and PTEN expression were detected by real-time PCR (RT-PCR). The cell viability and apoptosis were detected by MTT, colony formation and flow cytometry assay, respectively. Dual-luciferase reporter assay was adopted to verify the targeting relationship between miR-92a and PTEN. Besides, we measured the relative protein levels of PTEN and p-AKT/AKT by Western blot. MiR-92a was significantly highly expressed in OC cells, and its high expression could notably enhance paclitaxel resistance, cell proliferation and colony formation, as well as inhibit apoptosis in SKOV3-Tax cells. Further luciferase reporter assay and expression detection showed that miR-92a could target and regulate PTEN and that there was a targeted relationship between them. In addition, further exploration of the mechanism revealed that miR-92a regulated PTEN/Akt signaling pathway. MiR-92a not only promotes the proliferation, colony formation and paclitaxel resistance of SKOV3-Tax cells in OC, but also inhibits apoptosis, and it may be related to the regulation of the PTEN/Akt signaling pathway. MiR-92a serves as a potential biomarker for the malignant biological behavior of OC cells.

Cyclin dependent kinase 14 as a paclitaxel-resistant marker regulated by the TGF-β signaling pathway in human ovarian cancer.

Cyclin dependent kinase 14 (CDK14) plays a central role in the control of cell proliferation and cell cycle progression. However, the specific function and regulatory mechanism of CDK14 on paclitaxel (PTX) resistance in ovarian cancer (OC) remain unclear. The present study demonstrated that CDK14 was overexpressed in OC tissues and cells at mRNA and protein levels detected by qRT-PCR, Western blot, and immunohistochemistry. Survival analysis showed that elevated CDK14 was related to the poor prognosis of OC patients. Overexpression of CDK14 was correlated with chemoresistance in OC. The expression level of CDK14 was higher in PTX-resistant OC cells (SK3R-PTX and OV3R-PTX) than in their counterpart-sensitive cells (SK-OV-3 and OVCAR-3). Knockdown of CDK14 decreased multidrug resistance 1 (MDR1) and β-catenin expression in SK3R-PTX and OV3R-PTX cells and resensitized OC cells to PTX by decreasing cell proliferation and inducing cell apoptosis. Administration of transforming growth factor (TGF)-β1 decreased CDK14 protein in PTX-resistant OC cells. The inhibitory effect of TGF-β1 on CDK14 expression was abolished in the presence of a TGF-β type I receptor kinase inhibitor (SB-431542). Furthermore, TGF-β signal transducer Smad2 protein directly bound to the region -437 to -446 upstream of the CDK14 transcription start site (TSS), resulting in downregulating the expression of CDK14. These data indicate that CDK14 is a PTX-resistant marker and is regulated by the TGF-β signaling pathway. Targeting CDK14 to enhance the sensitivity of PTX may provide a new therapeutic strategy for reversing the PTX resistance in OC.

PGAM1 Promotes Glycolytic Metabolism and Paclitaxel Resistance via Pyruvic Acid Production in Ovarian Cancer Cells.

Enhanced glycolysis occurs in most human cancer cells and is related to chemoresistance. However, detailed mechanisms remain vague. Using proteinomics analysis, we found that the glycolytic enzyme Phosphoglycerate mutase 1 (PGAM1) was highly expressed in the paclitaxel-resistant ovarian cancer cell line SKOV3-TR30, as compared to its parental cell line SKOV3. Cell Counting Kit-8 proliferation experiment, plasmids and siRNA transfection, pyruvic acid and lactic acid production detection, immunofluorescence staining of functional mitochondria and oxygen consumption rate and extracellular acidification rate measurement were uesd to assess the glycolytic metabolism and paclitaxel resistance in ovarian cancer cells. The expression and prognostic effect of PGAM1 in 180 ovarian cancer patients were analyzed. SKOV3-TR30 cells display higher glycolytic flux and lower mitochondrial function than SKOV3 cells. Down-regulation of PGAM1 in SKOV3-TR30 cells resulted in decreased paclitaxel resistance. Up-regulation of PGAM1 in SKOV3 cells led to enhanced paclitaxel resistance. Analysis of the glycolytic flux revealed that PGAM1-mediated pyruvic acid or lactic acid production could modulate the capabilities of ovarian cancer cell resistance to paclitaxel. Our data also show high expression of PGAM1 as significantly correlated with reduced overall survival and reduced progression free survival in ovarian cancer patients. PGAM1 acts to promote paclitaxel resistance via pyruvic acid and/or lactate production in ovarian cancer cells. Inhibiting PGAM1 may provide a new approach to favorably alter paclitaxel resistance in ovarian cancer.

Inhibition of Glutamine Uptake Resensitizes Paclitaxel Resistance in SKOV3-TR Ovarian Cancer Cell via mTORC1/S6K Signaling Pathway

Ovarian cancer is a carcinoma that affects women and that has a high mortality rate. Overcoming paclitaxel resistance is important for clinical application. However, the effect of amino acid metabolism regulation on paclitaxel-resistant ovarian cancer is still unknown. In this study, the effect of an amino acid-deprived condition on paclitaxel resistance in paclitaxel-resistant SKOV3-TR cells was analyzed. We analyzed the cell viability of SKOV3-TR in culture conditions in which each of the 20 amino acids were deprived. As a result, the cell viability of the SKOV3-TR was significantly reduced in cultures deprived of arginine, glutamine, and lysine. Furthermore, we showed that the glutamine-deprived condition inhibited mTORC1/S6K signaling. The decreased cell viability and mTORC1/S6K signaling under glutamine-deprived conditions could be restored by glutamine and α-KG supplementation. Treatment with PF-4708671, a selective S6K inhibitor, and the selective glutamine transporter ASCT2 inhibitor V-9302 downregulated mTOR/S6K signaling and resensitized SKOV3-TR to paclitaxel. Immunoblotting showed the upregulation of Bcl-2 phosphorylation and a decrease in Mcl-1 expression in SKOV3-TR via the cotreatment of paclitaxel with PF-4708671 and V-9302. Collectively, this study demonstrates that the inhibition of glutamine uptake can resensitize SKOV3-TR to paclitaxel and represents a promising therapeutic target for overcoming paclitaxel resistance in ovarian cancer.

CCL2 overexpression is associated with paclitaxel resistance in ovarian cancer cells via autocrine signaling and macrophage recruitment

Tumor cells can secret various cytokines and chemokines, which affect the tumor cells themselves and the neighboring cells. Here, we observed that human ovarian cancer (OC) cells developed resistance to paclitaxel treatment following culture with the conditioned medium (CM) derived from paclitaxel-resistant OC (OCTR) cells. A cytokine array revealed that both OCTR cells secreted large amounts of CC chemokine ligand 2 (CCL2). CCL2 and its receptor, CCR2, were overexpressed in OCTR cells. CCL2 expression was associated with worse progression-free survival in patients with ovarian cancer. The inhibition of the CCL2/CCR2 axis suppressed the chemoresistance induced by OCTR-CM. The enhanced expression and production of CCL2 in OC cells were mediated via the NF-κB pathway, and stimulated the activation of the PI3K/Akt pathway, which resulted in the development of paclitaxel resistance in OC cells. Additionally, the OCTR cells significantly increased the migration of macrophages, which was also associated with the overproduction of CCL2 in chemoresistant cancer cells. The macrophages stimulated by OCTR cells expressed high levels of markers of M2 phenotype, and their CM significantly decreased the paclitaxel responsiveness of OC cells. The administration of a CCR2 inhibitor to a murine model significantly improved the paclitaxel sensitivity. These data suggested that apart from inducing chemoresistance in OC cells by acting as an autocrine factor, CCL2 also functions as a chemokine that induces the chemotaxis of macrophages, which may contribute to chemoresistance. Therefore, targeting the CCL2/CCR2 signaling axis may improve the therapeutic response of patients with ovarian cancer to paclitaxel.

Low-Intensity Focused Ultrasound Targeted Microbubble Destruction Enhanced Paclitaxel Sensitivity by Decreasing Autophagy in Paclitaxel-Resistant Ovarian Cancer.

Ultrasound targeted microbubble destruction (UTMD) was introduced as a promising method to improve anti-tumor therapeutic efficacy, while minimizing side effects to healthy tissues. Nevertheless, the acoustical phenomenon behind the UTMD as well as the exact mechanisms of autophagy action involved in the increased anti-cancer response are still not fully understood. Therefore, we examined the drug resistance-reversing effects of low-intensity focused ultrasound with microbubble (LIFU+MB) in paclitaxel (PTX)-resistant ovarian cancer cells. Cell viability was evaluated using CCK8 (Cell Counting Kit-8), apoptosis was detected by flow cytometry, quantitative real-time PCR and Western blot were used to detect the expressions of mRNA and protein, and autophagy was observed by transmission electron microscopy (TEM). We revealed that the level of autophagy was increased (p < 0.05) in PTX-resistant ovarian cancer cells. Treatment of LIFU+MB combined with PTX can notably inhibit proliferation as well as increase apoptosis (p < 0.01) in drug-resistant cells. We proposed that LIFU+MB might affect the sensitivity of ovarian cancer cells to PTX by modulating autophagy. To verify the hypothesis, we analyzed the autophagy level of drug-resistant cells after the treatment of LIFU+MB and found that autophagy was significantly inhibited. Altogether, our findings demonstrated that LIFU+MB could reverse PTX resistance in ovarian cancer via inhibiting autophagy, which provides a novel strategy to improve chemosensitivity in ovarian cancer.

Effect of ALDH1A1 Gene Knockout on Drug Resistance in Paclitaxel and Topotecan Resistant Human Ovarian Cancer Cell Lines in 2D and 3D Model.

Ovarian cancer is the most common cause of gynecological cancer death. Cancer Stem Cells (CSCs) characterized by drug transporters and extracellular matrix (ECM) molecules expression are responsible for drug resistance development. The goal of our study was to examine the role of aldehyde dehydrogenase 1A1 (ALDH1A1) expression in paclitaxel (PAC) and topotecan (TOP) resistant ovarian cancer cell lines. In both cell lines, we knocked out the ALDH1A1 gene using the CRISPR/Cas9 technique. Additionally, we derived an ALDH1A1 positive TOP-resistant cell line with ALDH1A1 expression in all cells via clonal selection. The effect of ALDH1A1 gene knockout or clonal selection on the expression of ALDH1A1, drug transporters (P-gp and BCRP), and ECM (COL3A1) was determined by Q-PCR, Western blot and immunofluorescence. Using MTT assay, we compared drug resistance in two-dimensional (2D) and three-dimensional (3D) cell culture conditions. We did not observe any effect of ALDH1A1 gene knockout on MDR1/P-gp expression and drug resistance in the PAC-resistant cell line. The knockout of ALDH1A1 in the TOP-resistant cell line resulted in a moderate decrease of BCRP and COL3A1 expression and weakened TOP resistance. The clonal selection of ALDH1A1 cells resulted in very strong downregulation of BCPR and COL3A1 expression and overexpression of MDR1/P-gp. This finally resulted in decreased resistance to TOP but increased resistance to PAC. All spheroids were more resistant than cells growing as monolayers, but the resistance mechanism differs. The spheroids’ resistance may result from the presence of cell zones with different proliferation paces, the density of the spheroid, ECM expression, and drug capacity to diffuse into the spheroid.

Circ_0025033 deficiency suppresses paclitaxel resistance and malignant development of paclitaxel-resistant ovarian cancer cells by modulating the miR-532-3p/FOXM1 network

Background Ovarian cancer (OC) is the main cause of cancer-related death in women, and drug resistance is a leading cause of treatment failure. Recently, the involvement of circular RNAs (circRNAs) in cancer progression has become an area of increased investigation. The objective of this study is to uncover the function and regulatory mechanism of circ_0025033 in paclitaxel (PTX)-resistant OC cells. Methods The expression of circ_0025033, FOXM1 and miR-532-3p was investigated using quantitative real-time polymerase chain reaction (qRT-PCR), and the protein expression of FOXM1 was quantified by western blot. Cell biological functions, including cell viability, migration/invasion and apoptosis, were explored using 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays, transwell assays and flow cytometry assays. The interaction between miR-532-3p and circ_0025033 or FOXM1 predicted by bioinformatics analysis was validated by pull-down assay and dual-luciferase reporter assay. Exosomes were isolated to determine the further function of circ_0025033. Result Circ_0025033 and FOXM1 were highly expressed, while miR-532-3p was poorly expressed in OC tissues and cells, and the expression pattern was greater in PTX-resistant OC cells. Circ_0025033 knockdown lessened PTX resistance, suppressed migration/invasion and promoted apoptosis of PTX-resistant cells. With respect to mechanism, circ_0025033 upregulated the expression of FOXM1 by targeting miR-532-3p, and circ_0025033 knockdown blocked the malignant activities of PTX-resistant OC cells by enriching miR-532-3p and suppressing FOXM1. Exosomes derived from PTX-resistant cells with circ_0025033 knockdown also could repress the malignant actions of PTX-resistant OC cells. Conclusion Circ_0025033 downregulation impaired PTX resistance and malignant activities of PTX-resistant OC cells by regulating the miR-532-3p/FOXM1 network.