Patients with renal cell carcinoma (RCC) often develop distant metastasis and the specific molecular mechanism remains poorly understood. In our study, we demonstrated that MUC15, a subtype of mucins family, could suppress the progression of RCC by inhibiting PI3K/AKT signaling. Firstly, we observed that MUC15 was notably decreased in RCC compared to normal tissue. Furthermore, we showed that MUC15 could negatively modulate the migration and invasion of RCC in vitro and in vivo. Mechanistically, we found that knocking-down of MUC15 could active the PI3K/AKT signaling by increasing the AKT phosphorylation and subsequently increase the mRNA and protein expression of MMP2 and MMP9. Interruption of the AKT pathway with the specific inhibitor LY294002 could reverse the expression of MMPs. Therefore, our study clarify the novel function of MUC15 in RCC, which may provide a new sight to diagnose and prevent RCC metastasis.
The mechanistic (formally “mammalian”) target of rapamycin (mTOR) pathway serves as a crucial regulator of various biological processes such as cell growth and cancer progression. In bladder cancer, recent discoveries showing the cancer-promoting role of mTOR complex 1 have attracted wide attention. However, the regulation of mTOR signaling in bladder cancer is complicated and the underlying mechanism remains elusive. Here, we report that the deubiquitinating enzyme, ovarian tumor domain-containing protein 5 (OTUD5), can activate the mTOR signaling pathway, promote cancer progression, and show its oncogenic potential in bladder cancer. In our study, we found that OTUD5 deubiquitinated a RING-type E3 ligase, RNF186, and stabilized its function. In addition, the stabilization of RNF186 further led to the degradation of sestrin2, which is an inhibitor of the mTOR signaling pathway. Together, we provide novel insights into the pathogenesis of bladder cancer and first prove that OTUD5 can promote bladder cancer progression through the OTUD5-RNF186-sestrin2-mTOR axis, which may be exploited in the future for the diagnosis and treatment of this malignancy.
Silibinin (SB), a flavonoid extracted from milk thistle seeds, has been found to exert antitumor effects in numerous tumor types. Our previous study reported that SB had anti-metastatic effects in prostate cancer (PCa). However, the exact underlying molecular mechanisms remain to be determined. The present study aimed to investigate the effects of SB on the migration, invasion and epithelial-mesenchymal transition (EMT) of castration-resistant PCa (CRPC) cells using wound healing, Transwell assays, and western blotting. The results revealed that SB treatment significantly inhibited the migration and invasion of CRPC cell lines. Moreover, SB was confirmed to activate autophagy, as determined using LC3 conversion, LC3 turnover and LC3 puncta assays. Further mechanistic studies indicated that the expression levels of Yes-associated protein (YAP) were downregulated in an autophagy-dependent manner after SB treatment. In addition, the SB-induced autophagic degradation of YAP was associated with the anti-metastatic effects of SB in CRPC. In conclusion, the findings of the present study suggested that SB might inhibit the migration, invasion and EMT of PCa cells by regulating the autophagic degradation of YAP, thus representing a potential novel treatment strategy for metastatic CRPC.
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