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Triptolide inhibits JAK2/STAT3 signaling and induces lethal autophagy through ROS generation in cisplatin‑resistant SKOV3/DDP ovarian cancer cells.

ABSTRACT: Advanced and recurrent ovarian cancer has a poor prognosis and is frequently resistant to numerous therapeutics; thus, safe and effective drugs are needed to combat this disease. Previous studies have demonstrated that triptolide (TPL) exhibits anticancer and sensitization effects against cisplatin (DDP)‑resistant ovarian cancer both in vitro and in vivo by inducing apoptosis; however, the involvement of autophagy induced by TPL in resistant ovarian carcinoma remains unclear. In the present study, the results revealed that TPL induced autophagy to facilitate SKOV3/DDP ovarian cancer cell death. The xenograft experiment revealed that the autophagy inhibitor CQ significantly reduced TPL‑mediated chemosensitization and tumor growth inhibition. Mechanically, TPL‑induced autophagy in SKOV3/DDP cells was associated with the induction of ROS generation and inhibition of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription‑3 (STAT3) pathway. The inhibitory effect of TPL on the JAK2/STAT3 pathway could be restored in the presence of the antioxidant NAC. Furthermore, it was further determined that TPL disrupted the interaction between Mcl‑1 and Beclin1, which was prevented by the JAK2/STAT3 signaling activator IL‑6. Overall, the present results revealed a novel molecular mechanism whereby TPL induced lethal autophagy through the ROS‑JAK2/STAT3 signaling cascade in SKOV3/DDP cells. The present study has provided the groundwork for future application of TPL in the treatment of ovarian cancer.

SUBMITTER: Zhong Y

PROVIDER: S-EPMC8020210 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Triptolide has been proven to possess anticancer efficacy; however, its application in the clinical practice was limited by poor water solubility, hepatotoxicity, and nephrotoxicity. In this study, a triptolide-loaded exosomes delivery system (TP-Exos) was constructed and its effects on the proliferation and apoptosis of SKOV3 cells in vitro and in vivo were observed. SKOV3-exosomes (SK-Exos) were collected by ultracentrifugation and ultrafiltration centrifugation. TP-Exos was constructed by sonication and ultrafiltration centrifugation. SK-Exos and TP-Exos were characterized by transmission electron microscopy, western blotting, nanoparticle-tracking analysis, and high-performance liquid chromatography. Cellular uptake of exosomes, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, bromodeoxyuridine (BrdU) cell proliferation assay, and cell apoptosis experiment were used to study the effect of TP-Exos on ovarian cancer in vitro. Tumor-targeting study of exosomes, monitoring the tumor volume of mice, and TdT-mediated dUTP Nick-End labeling (TUNEL) assay were used to evaluate the effect of TP-Exos on ovarian cancer in vivo. The toxicity of TP-Exos in vivo was evaluated by liver and kidney function and histopathology of major organs (heart, liver, spleen, lung, kidney, and ovary). The results revealed that TP-Exos not only have the general characteristics of exosomes but also have high drug encapsulation efficiency. Besides, PKH26 labeled exosomes (PKH26-Exos) could be uptaken by SKOV3 cells, and Dir labeled exosomes (Dir-Exos) could be enriched to the tumor site of tumor bearing mice. Furthermore, the cytotoxic and apoptotic effects on SKOV3 cells of TP-Exos were weaker than those of free TP, and tumor cell proliferation inhibition and tumor growth inhibition were stronger than that of free TP. Moreover, TP-Exos have toxic effect on liver and spleen. In conclusion, the TP-Exos could be a promising strategy for ovarian cancer, but they need to be further optimized to attenuate the damage to liver and spleen.

Project description:IntroductionHepatocellular carcinoma (HCC) accounts for 80% of all liver cancers and is the 2nd leading cause of cancer-related death in Taiwan. Various factors, including rapid cell growth, a high recurrence rate and drug resistance, make HCC difficult to cure. Moreover, the survival rate of advanced HCC patients treated with systemic chemotherapy remains unsatisfactory. Hence, the identification of novel molecular targets and the underlying mechanisms of chemoresistance in HCC and the development more effective therapeutic regimens are desperately needed.MethodsAn MTT assay was used to determine the cell viability after cisplatin or doxorubicin treatment. Western blotting, qRT‒PCR and immunohistochemistry were utilized to examine the protein tyrosine phosphatase IVA3 (PTP4A3) level and associated signaling pathways. ELISA was utilized to analyze the levels of the inflammatory cytokine IL-6 influenced by cisplatin, doxorubicin and PTP4A3 silencing.ResultsIn this study, we found that PTP4A3 in the cisplatin/doxorubicin-resistant microarray was closely associated with the overall and recurrence-free survival rates of HCC patients. Cisplatin or doxorubicin significantly reduced cell viability and decreased PTP4A3 expression in hepatoma cells. IL-6 secretion increased with cisplatin or doxorubicin treatment and after PTP4A3 silencing. Furthermore, PTP4A3 was highly expressed in tumor tissues versus adjacent normal tissues from HCC patients. In addition, we evaluated the IL-6-associated signaling pathway involving STAT3 and JAK2, and the levels of p-STAT3, p-JAK2, STAT3 and JAK2 were obviously reduced with cisplatin or doxorubicin treatment in HCC cells using Western blotting and were also decreased after silencing PTP4A3. Collectively, we suggest that cisplatin or doxorubicin decreases HCC cell viability via downregulation of PTP4A3 expression through the IL-6R-JAK2-STAT3 cascade.DiscussionTherefore, emerging evidence provides a deep understanding of the roles of PTP4A3 in HCC cisplatin/doxorubicin chemoresistance, which can be applied to develop early diagnosis strategies and reveal prognostic factors to establish novel targeted therapeutics to specifically treat HCC.

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Triptolide inhibits JAK2/STAT3 signaling and induces lethal autophagy through ROS generation in cisplatin‑resistant SKOV3/DDP ovarian cancer cells.

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