Anti-tumor effects of deubiquitinating enzyme inhibitor PR-619 in human chondrosarcoma through reduced cell proliferation and endoplasmic reticulum stress-related apoptosis.

Chondrosarcoma, a treatment-resistant cancer with limited therapeutic options, lacks significant advancements in treatment methods. However, PR-619, a novel inhibitor of deubiquitinating enzymes, has demonstrated anti-tumor effects in various malignancies. This study aimed to investigate the impact of PR-619 on chondrosarcoma both in vitro and in vivo. Two human chondrosarcoma cell lines, SW11353 and JJ012, were utilized. Cell viability was assessed using an MTT assay, while flow cytometry enabled the detection of apoptosis and cell cycle progression. Western blotting analyses were conducted to evaluate apoptosis, cell stress, and endoplasmic reticulum (ER) stress. Furthermore, the in vivo anti-tumor effects of PR-619 were examined using a xenograft mouse model. The results revealed that PR-619 induced cytotoxicity, apoptosis, and cell cycle arrest at the G0/G1 stage by activating caspases, PARP cleavage, and p21. Moreover, PR-619 increased the accumulation of polyubiquitinated proteins and ER stress by activating IRE1, GRP78, caspase-4, CHOP, and other cellular stress responses, including JNK activation. In vivo analysis demonstrated that PR-619 effectively inhibited tumor growth with minimal toxicity in the xenograft mouse model. These findings provide evidence of the anti-tumor effects and induction of cellular and ER stress by PR-619 in human chondrosarcoma, suggesting its potential as a novel therapeutic strategy for in human chondrosarcoma.

The UCHL5 inhibitor b-AP15 overcomes cisplatin resistance via suppression of cancer stemness in urothelial carcinoma.

Urothelial carcinoma (UC) comprises the majority of bladder cancers. Standard platinum-based chemotherapy has a response rate of approximately 50%, but drug resistance develops after short-term treatment. Deubiquitinating (DUB) enzyme inhibitors increase protein polyubiquitination and endoplasmic reticulum (ER) stress, which might further suppress cancer stemness and overcome cisplatin resistance. Therefore, we investigated the cytotoxic effect and potential mechanisms of b-AP15 on urothelial carcinoma. Our results revealed that b-AP15 induced ER stress and apoptosis in BFTC905, T24, T24/R (cisplatin-resistant), and RT4 urothelial carcinoma cell lines. Inhibition of the MYC signaling pathway and cancer stemness by b-AP15 was confirmed by RNA sequencing, RT-PCR, immunoblotting, and sphere-forming assays. In the mouse xenograft model, the combination of b-AP15 and cisplatin showed superior therapeutic effects compared with either monotherapy.

PR-619, a General Inhibitor of Deubiquitylating Enzymes, Diminishes Cisplatin Resistance in Urothelial Carcinoma Cells through the Suppression of c-Myc: An In Vitro and In Vivo Study.

Cisplatin-based chemotherapy is the standard treatment for bladder urothelial carcinoma (UC). Most patients experience chemoresistance, the primary cause of treatment failure, which leads to disease relapse. The underlying mechanism of chemoresistance involves reduced apoptosis. In this study, we investigated the antitumor effect of the deubiquitylating enzyme inhibitor PR-619 in cisplatin-resistant bladder UC. Deubiquitinase (ubiquitin-specific protease 14 (USP14) and USP21) immunohistochemical staining demonstrated that deubiquitination is related to chemoresistance in patients with metastatic UC and may be a target for overcoming chemoresistance. Cytotoxicity and apoptosis were assessed using fluorescence-activated flow cytometry and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium assay, and PR-619 was found to enhance the cytotoxic and apoptotic effects of cisplatin in cisplatin-resistant T24/R cells. Mitigated cisplatin chemoresistance was associated with the concurrent suppression of c-Myc expression in T24/R cells. Moreover, the expression of c-Myc was upregulated in human bladder UC specimens from patients with chemoresistance. Experiments in a xenograft nude mouse model confirmed that PR-619 enhanced the antitumor effects of cisplatin. These results are promising for the development of therapeutic strategies to prevent UC chemoresistance through the combined use of chemotherapeutic agents/deubiquitination inhibitors (PR-619) by targeting the c-Myc pathway.

Nerolidol inhibits proliferation of leiomyoma cells via reactive oxygen species-induced DNA damage and downregulation of the ATM/Akt pathway.

Nerolidol (3,7,11-trimethyl-1,6,10-dodecatrien-3-ol), a sesquiterpene alcohol present in aromatic essential oils of numerous plants, has been reported to possess anticancer activity. The potential therapeutic effect of nerolidol on uterine fibroids (UF), the most common benign tumor of the uterus worldwide, is unknown. In this study, we examined the anti-UF potential of nerolidol in ELT3 cells, a rat leiomyoma cell line widely used as an in vitro model, to identify the potential therapeutic agents for UF. We observed that treatment with cis- or trans-nerolidol inhibited cell proliferation in a dose-dependent manner and induced cell cycle arrest in the G1 phase, which was accompanied by reduction in Akt phosphorylation and downregulation of cyclin D1, cyclin-dependent kinase 4 (CDK4), and CDK6 protein expression. The proliferation-inhibiting activity of nerolidol correlated with the generation of intracellular reactive oxygen species (ROS), which was suppressed by N-acetyl-l-cysteine, a ROS inhibitor. Nerolidol treatment also increased the percentage of cells for which tail moment could be calculated using an alkaline comet assay, and induced p-γH2AXser139 expression, which indicated induction of DNA damage. We also observed downregulation of ATM and its phosphorylation after nerolidol treatment; furthermore, treatment with KU-55933, an ATM kinase inhibitor, mimicked the inhibitory effects of nerolidol treatment on cell proliferation and Akt phosphorylation. In conclusion, nerolidol displayed anti-UF activity in a leiomyoma cell model via ROS-induced DNA damage and G1 phase cell cycle arrest by inhibiting the expression and activation of the ATM/Akt pathway. Our data suggests that nerolidol is a potential therapeutic agent for UF.