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PTOV1 promotes cisplatin-induced chemotherapy resistance by activating the nuclear factor kappa B pathway in ovarian cancer

ABSTRACT: Chemotherapy resistance is a bottleneck for ovarian cancer treatment; therefore, revealing its regulatory mechanism is critical. In the present study, we found that prostate tumor overexpressed-1 (PTOV1) was upregulated significantly in ovarian cancer cells and tissues. Patients with high PTOV1 levels had a poor outcome. In addition, PTOV1 overexpression increased CDDP (cisplatin) resistance, while PTOV1 knockdown inhibited CDDP resistance, as determined using cell viability assays, apoptosis assays, and an animal model. Mechanistic analysis showed that PTOV1 increased nuclear factor kappa B (NF-?B) pathway activity, reflected by increased nuclear translocation of its p65 subunit and the phosphorylation of inhibitor of nuclear factor kappa-B kinase subunits alpha and beta, which are markers of NF-?B pathway activation. Inhibition of the NF-?B pathway in PTOV1-overexpressing ovarian cancer cells increased CDDP-induced apoptosis, suggesting that PTOV1 promoted chemotherapy resistance by activating the NF-?B pathway. In summary, we identified PTOV1 as a prognostic factor for patients with ovarian cancer. PTOV1 might be a target for inhibition of chemotherapy resistance. Graphical Abstract Chemotherapy resistance is a bottleneck of ovarian cancer treatment. In this study, we found PTOV1 not only served as a prognostic factor for ovarian cancer patients but also was a novel target for inhibition of cisplatin resistance.

SUBMITTER: Shen H

PROVIDER: S-EPMC7937561 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Various studies have revealed that the Hedgehog (Hh) signaling pathway promotes ovarian cancer invasion, migration and drug resistance. Previous studies by our group have identified a set of genes, including multidrug resistance gene 1 (MDR1), that are regulated by Hh signaling in ovarian cancer. However, the association between Hh signaling activation and MDR1 expression requires further validation. In the present study, reverse transcription‑quantitative PCR or western blot assays were used to evaluate the mRNA and protein expression levels of MDR1, Sonic Hh (Shh), glioma‑associated oncogene 2 (Gli2), Gli1 and γ‑phosphorylated H2A.X variant histone (γ‑H2AX). MTT and colony‑formation assays were performed to determine the effect of cisplatin (DDP) after inhibiting the Hh pathway in ovarian cancer cells. The results indicated that MDR1, Gli2 and Shh levels were much higher in SK‑OV‑3 cells with acquired DDP resistance than in native SK‑OV‑3 cells. ES‑2 cells with overexpression of Gli2 were capable of efficiently forming colonies in the presence of low DDP concentrations. By contrast, Gli2 knockdown in SK‑OV‑3 cells decreased the colony‑forming ability under the same concentration of DDP. As determined by MTT assays, knockdown of Gli2 or targeting of the Hh signaling pathway with either Gli‑antagonist 61 (GANT61) or cyclopamine, in combination with DDP treatment, diminished the viability of ES‑2 and SK‑OV‑3 cells, whereas Gli2 overexpression increased the viability of ES‑2 cells in the presence of DDP. Knockdown of Gli2 or targeting the Hh signaling pathway with GANT61 also increased γ‑H2AX levels but decreased the expression of MDR1 in the presence of DDP. MDR1 expression is regulated by the Hh signaling pathway and is likely a downstream transcription factor of Gli2. In conclusion, targeting the Hh signaling pathway increases the sensitivity of ovarian cancer to DDP. MDR1 is a target gene of the Hh signaling pathway and this pathway may affect chemoresistance of ovarian cancer to DDP via MDR1.

Project description:BackgroundChemotherapy is one of the primary treatments for ovarian cancer patients. Autophagy has been linked to chemotherapy resistance in tumor cells. Recent studies have suggested that fibroblast growth factor 19 (FGF19) may be involved in the onset and progression of malignancies. However, the relationship between FGF19 and autophagy in ovarian cancer is still unknown.MethodsNext-generation sequencing (NGS) was conducted to analyze gene mutation profiles of 62 cases of high grade serous ovarian cancer (HGSOC). Fluorescence in situ hybridization (FISH) was performed to validate the amplification of FGF19 in HGSOC tissues. Quantitative PCR (qPCR) and immunohistochemistry (IHC) were used to analyze the difference of FGF19 in mRNA and protein expression. Meanwhile, bioinformatics techniques were used to analyze the expression profiles of FGF19 and the correlation with prognosis. Besides, immunofluorescence, transmission electron microscopy and Cell Counting Kit 8 (CCK-8) were used to investigate the potential mechanisms.ResultsIn this study, we found that FGF19 promotes cisplatin resistance in ovarian cancer cells by inducing autophagy. NGS analysis of 62 HGSOC cases identified a significantly amplified gene, FGF19. In addition, the expression level of FGF19 in ovarian cancer samples was higher than that in normal samples. FISH results showed a positive correlation between amplification and expression of FGF19. Knockdown of FGF19 inhibited the cell autophagy through decrease in the expression of LC3 and Beclin 1, and increase in the expression of SQSTM1/p62. Furthermore, we observed that p38 MAPK phosphorylation was down-regulated after FGF19 knockdown. IFN-γ, a potential p38 MAPK activator, counteracted the inhibition of cell autophagy and the anti-proliferation effect of cisplatin induced by FGF19 knockdown in ovarian cancer cells.ConclusionFGF19 increases autophagy and chemoresistance in ovarian cancer by activating the p38 MAPK pathway. These results could point to FGF19 being a potential therapeutic target for ovarian cancer.

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PTOV1 promotes cisplatin-induced chemotherapy resistance by activating the nuclear factor kappa B pathway in ovarian cancer

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