Mivebresib synergized with PZ703b, a novel Bcl-xl PROTAC degrader, induces apoptosis in bladder cancer cells via the mitochondrial pathway.

Bladder cancer is a common urinary cancer that still lacks effective treatments. In the present study, we evaluated the effect of BET inhibitor, mivebresib, in combination with PZ703b, a Bcl-xl PROTAC, on apoptosis in bladder cancer cells. The results revealed that mivebresib and PZ703b synergistically decreased the viabilities of bladder cancer cells. Co-treatment of mivebresib and PZ703b induced apoptosis in bladder cancer cells via the mitochondrial pathway in a caspase-dependent manner. Mechanistically, mivebresib and PZ703b treatment inhibited the expression of Mcl-1 and Bcl-xl, accompanied by upregulation of Bim. Hence, co-treatment of mivebresib and PZ703b rebalanced the level of pro- and anti-apoptotic Bcl-2 proteins in cells. Further investigations showed that forced expression of Mcl-1 or Bcl-xl markedly protected bladder cancer cells from apoptosis induced by combination treatment of mivebresib and PZ703b. In addition, knockdown of Bim also inhibited the cell death induced by mivebresib/PZ703b in bladder cancer cells. In summary, our findings reveal that the combination treatment of mivebresib and PZ703b represents a novel promising strategy to treat bladder cancer.

An increase in long non-coding RNA PANDAR is associated with poor prognosis in clear cell renal cell carcinoma.

BACKGROUND: Nearly 30% of clear cell renal cell carcinoma (ccRCC) patients present with metastasis at the time of diagnosis, and the prognosis for these patients is poor. Therefore, novel potential prognostic biomarkers and therapeutic targets for ccRCC could be helpful. Emerging evidence indicates that lncRNAs play important roles in cancer tumorigenesis and could be used as potential biomarkers or therapeutic targets. PANDAR (promoter of CDKN1A antisense DNA damage activated RNA) is a relatively novel lncRNA that plays an important role in the development of multiple cancers. However, the clinical significance and molecular mechanism of PANDAR in ccRCC are still elusive. In the present study, we attempted to elucidate the role of PANDAR in ccRCC. METHODS: The relative expression level of lncRNA PANDAR was quantified by real-time qPCR in 62 paired ccRCC tissues and in renal cancer cell lines, and its association with overall survival was assessed by statistical analysis. The biological functions of lncRNA PANDAR on ccRCC cells were determined both in vitro and in vivo. RESULTS: PANDAR expression was significantly upregulated in tumor tissues and cell lines compared with normal counterparts. Moreover, PANDAR served as an independent predictor of overall survival, and increased PANDAR expression was positively correlated with an advanced TNM stage. Further experiments demonstrated that PANDAR silencing can significantly inhibit cell proliferation and invasion, induce cell cycle arrest in the G1 phase and significantly promote apoptosis in 7860 and Caki-1 cell lines. In addition, in vivo experiments confirmed that downregulation of PANDAR inhibited the tumorigenic ability of 7860 cells in nude mice. Silencing of PANDAR also inhibited the expression of Bcl-2 and Mcl-1 and upregulated the expression of Bax in vivo. CONCLUSIONS: Our results suggest that PANDAR is involved in ccRCC progression and may serve as a potential prognostic biomarker and therapeutic target.

Abietic acid induces ferroptosis via the activation of the HO-1 pathway in bladder cancer cells.

BACKGROUND: Bladder cancer (BC) is a common urological malignancy that still lacks effective treatments. Abietic acid (AA) is an abietane diterpene that possesses various biological activities, including antitumor activity. This study aimed at evaluating the effects of AA on BC cells. MATERIALS AND METHODS: The 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to assess the effects of AA on the viability of BC cells. Annexin-V and FITC staining was used to assess cellular death. The type of cell death was determined by the administration of various specific cell death inhibitors. Commercial kits were used to measure the levels of reactive oxygen species (ROS), intracellular iron, malondialdehyde (MDA), and glutathione (GSH). Real-time polymerase chain reaction (RT-PCR) and western blot analysis were used to assay mRNA and protein levels, respectively. The role of glutathione peroxidase 4 (GPX4) in the antitumor effects of AA was evaluated using the forced expression of GPX4 in BC cells. The impact of HO-1 on the antitumor effects of AA was examined by gene silencing and pharmacological inhibition of the protein. Finally, the antitumor effects of AA were evaluated in xenograft models. RESULTS: AA selectively inhibited the viability of BC cells but not normal cells. AA-induced ferroptosis in BC cells was evidenced by the upregulation of ROS, intracellular iron, and MDA. AA treatment led to the downregulation of GPX4 and the upregulation of HO-1 in BC cells. Forced expression of GPX4 or inhibition of HO-1 resulted in decreased ferroptosis triggered by AA in BC cells. AA also showed synergistic effects with various chemotherapeutic agents against BC and inhibited the growth of BC cells in vivo. CONCLUSION: This study revealed AA-induced ferroptosis in BC cells both in vitro and in vivo. AA might be applied as a promising agent for the treatment of BC.

Chrysin induces cell growth arrest, apoptosis, and ER stress and inhibits the activation of STAT3 through the generation of ROS in bladder cancer cells.

Chrysin is a natural flavone that has various biological activities, including antitumor effects. However, the effect of chrysin on bladder cancer cells remains elusive. The present study investigated the effects of chrysin on bladder cancer cells and its underlying mechanisms. The results demonstrated that chrysin induced apoptosis via the intrinsic pathway, as evidenced by activation of caspase-9 and caspase-3, however not caspase-8. In addition, chrysin reduced the expression of anti-apoptotic B cell lymphoma (Bcl) proteins including Bcl-2, Mcl-1, Bcl-xl, and promoted the protein expression of pro-apoptotic Bcl-2 associated X, apoptosis regulator. Chrysin also induced endoplasmic reticulum stress via activation of the unfolded protein response of PRKR-like endoplasmic reticulum kinase, eIF2α and activating transcription factor 4 in bladder cancer cells. Additionally, chrysin inhibited the signal transducer and activator of transcription 3 pathway. Furthermore, the generation of reactive oxygen species (ROS) was detected following treatment with chrysin. The ROS scavenger N-acetylcysteine inhibited the antitumor effect of chrysin. Collectively, these results indicate chrysin may act as a promising therapeutic candidate for targeting bladder cancer.

Anti-proliferative effects of paeonol on human prostate cancer cell lines DU145 and PC-3.

Paeonol (Pae) is the main active ingredient from the root bark of Paeonia moutan and the grass of Radix Cynanchi Paniculati. Numerous reports indicate that Pae effectively inhibits several types of cancer lines. In this study, we report that Pae hinders prostate cancer growth both in vivo and in vitro. Human prostate cancer lines DU145 and PC-3 were cultured in the presence of Pae. The xenograft tumor in mice was established by subcutaneous injection of DU145 cells. Cell growth was measured by MTT, and the apoptosis was detected by the flow cytometry. Expression of Bcl-2, Bax, Akt, and mTOR were tested by western blotting assay. DU145 and PC-3 showed remarkable sensitivity to Pae, and exposure to Pae induced dose-and time-dependent growth inhibitory responses. Moreover, treatment of Pae promoted apoptosis and enhanced activities of caspase-3, caspase-8, and caspase-9 in DU145. Further work demonstrated Pae reduced expression of Bcl-2 and increased expression of Bax in DU145. Interestingly, we observed that Pae significantly decreased phosphorylated status of Akt and mTOR, and inhibitory effects of Pae and PI3K/Akt inhibitor on DU145 proliferation were synergistic. Finally, we confirmed that oral administration of Pae to the DU145 tumor-bearing mice significantly lowered tumor cell proliferation and led to tumor regression. Pae possesses inhibitory effects on prostate cancer cell growth both in vitro and in vivo, and the anti-proliferative effect may be closely related to its activation of extrinsic and intrinsic apoptotic pathway and inhibition of the PI3K/Akt pathway.

Expression and functional role of miR-29b in renal cell carcinoma.

OBJECTIVES: microRNAs (miRNAs) play essential roles in many tumors, including renal cell carcinoma (RCC). The aim of the present study was to investigate the expression and functional role of miR-29b in RCC and to identify its target genes. METHODS: We determined the expression of miR-29b in clear cell RCC (ccRCC) tissues and RCC cell lines (786-O, A498, and SN12-PM6) using quantitative real-time PCR (qRT-PCR). The associations between miR-29b expression and clinical pathological parameters and prognosis were explored. Besides, the role of miR-29b in the SN12-PM6 cells proliferation, apoptosis, cycle, and invasion were investigated after transduction with lentivirus vectors. The kines in family member 1B (KIF1B), possible miR-29b target genes, were predicted using bioinformatics approaches, as well as the role in the pathogenesis of RCC. RESULTS: Elevated expression of miR-29b was found in both tumor tissues and cell lines. High expression of miR-29b was significantly associated with tumor-node-metastasis (TNM) stage (P = 0.026) and the overall survival (P = 0.009) in the ccRCC. Inhibition of miR-29b expression could promote apoptosis, and inhibit proliferation and invasion ability in SN12-PM6 cells. Also, we confirmed that miR-29b could directly regulate the expression of KIF1B at the post transcriptional level. CONCLUSION: These data suggest that miR-29b acts as an oncomiR, promoting proliferation and invasion ability through KIF1B suppression, and it might be a potential marker for prognosis of RCC.

Anti-proliferative effects of paeonol on human prostate cancer cell lines DU145 and PC-3

Paeonol (Pae) is the main active ingredient from the root bark of Paeonia moutan and the grass of Radix Cynanchi Paniculati. Numerous reports indicate that Pae effectively inhibits several types of cancer lines. In this study, we report that Pae hinders prostate cancer growth both in vivo and in vitro. Human prostate cancer lines DU145 and PC-3 were cultured in the presence of Pae. The xenograft tumor in mice was established by subcutaneous injection of DU145 cells. Cell growth was measured by MTT, and the apoptosis was detected by the flow cytometry. Expression of Bcl-2, Bax, Akt, and mTOR were tested by western blotting assay. DU145 and PC-3 showed remarkable sensitivity to Pae, and exposure to Pae induced dose-and time-dependent growth inhibitory responses. Moreover, treatment of Pae promoted apoptosis and enhanced activities of caspase-3, caspase-8, and caspase-9 in DU145. Further work demonstrated Pae reduced expression of Bcl-2 and increased expression of Bax in DU145. Interestingly, we observed that Pae significantly decreased phosphorylated status of Akt and mTOR, and inhibitory effects of Pae and PI3K/Akt inhibitor on DU145 proliferation were synergistic. Finally, we confirmed that oral administration of Pae to the DU145 tumor-bearing mice significantly lowered tumor cell proliferation and led to tumor regression. Pae possesses inhibitory effects on prostate cancer cell growth both in vitro and in vivo, and the anti-proliferative effect may be closely related to its activation of extrinsic and intrinsic apoptotic pathway and inhibition of the PI3K/Akt pathway (AU)

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