Xingyuan Xiao

CircHIPK3 sponges miR-558 to suppress heparanase expression in bladder cancer cells.

Increasing evidences suggest that circular RNAs (circRNAs) exert crucial functions in regulating gene expression. In this study, we perform RNA‐seq and identify 6,154 distinct circRNAs from human bladder cancer and normal bladder tissues. We find that hundreds of circRNAs are significantly dysregulated in human bladder cancer tissues. We further show that circHIPK3, also named bladder cancer‐related circular RNA‐2 (BCRC‐2), is significantly down‐regulated in bladder cancer tissues and cell lines, and negatively correlates with bladder cancer grade, invasion as well as lymph node metastasis, respectively. Over‐expression of circHIPK3 effectively inhibits migration, invasion, and angiogenesis of bladder cancer cells in vitro and suppresses bladder cancer growth and metastasis in vivo. Mechanistic studies reveal that circHIPK3 contains two critical binding sites for the microRNA miR‐558 and can abundantly sponge miR‐558 to suppress the expression of heparanase (HPSE). Taken together, our findings provide evidence that circRNAs act as “microRNA sponges”, and suggest a new therapeutic target for the treatment of bladder cancer.

Silencing USP22 by asymmetric structure of interfering RNA inhibits proliferation and induces cell cycle arrest in bladder cancer cells

The ubiquitin specific peptidase 22 (USP22) is a positive regulator of the growth of tumors. However, little is known about the impact of USP22 knockdown on the growth of human bladder cells. In the present study, we designed a series of asymmetric interfering RNAs (aiRNAs) and compared the efficacy of aiRNA and conventional symmetric interfering RNA (siRNA) in the silencing of USP22 expression and the growth of human bladder EJ cells in vitro and in vivo. In comparison with transfection with the USP22-specific siRNA, transfection with 15/21 aiRNA was more potent in down-regulating the USP22 expression and inhibiting EJ cell proliferation in vitro. Furthermore, transfection with 15/21 aiRNA induced higher frequency of EJ cells arrested at the G0/G1 phases, but did not trigger EJ cell apoptosis. Moreover, transfection with either the siRNA or 15/21 aiRNA up-regulated the expression of p53 and p21, but down-regulated the expression of cyclin E and Mdm2 in EJ cells. The up-regulated p53 expression induced by the specific siRNA or aiRNA was abrogated by induction of Mdm2 over-expression. In addition, treatment with the specific siRNA or aiRNA inhibited the growth of implanted human bladder tumors in mice and the aiRNA had more potent anti-tumor activity in vivo. Therefore, our data suggest that knockdown of USP22 expression by the aiRNA may down-regulate the expression of Mdm2 and cyclin E, resulting in the up-regulated expression of p53 and p21 and leading to cell cycling arrest and inhibition of human bladder EJ cell proliferation. Our findings indicate that the USP22-specific aiRNA may be a novel approach for the intervention of human bladder tumors.

Gambogic acid inhibits TNF-α-induced invasion of human prostate cancer PC3 cells in vitro through PI3K/Akt and NF-κB signaling pathways

Aim:To investigate the mechanisms underlying the inhibitory effect of gambogic acid (GA) on TNF-α-induced metastasis of human prostate cancer PC3 cells in vitro.Methods:TNF-α-mediated migration and invasion of PC3 cells was examined using migration and invasion assays, respectively. NF-κB transcriptional activity and nuclear translocation were analyzed with luciferase reporter gene assays, immunofluorescence assays and Western blots. The ability of p65 to bind the promoter of Snail, an important mesenchymal molecular marker, was detected using a chromatin immunoprecipitation (ChIP) assay. After treatment with Snail-specific siRNA, the expression of invasiveness-associated genes was measured using quantitative real-time PCR and Western blot.Results:GA significantly inhibited the viability of PC3 cells at 1–5 μmol/L, but did not produce cytotoxic effect at the concentrations below 0.5 μmol/L. GA (0.125–0.5 μmol/L) dose-dependently inhibited the migration and invasion of PC3 cells induced by TNF-α (10 ng/mL). Moreover, the TNF-α-mediated activation of phosphatidylinositol-3-OH kinase/protein kinase B (PI3K/Akt) and NF-κB pathways was suppressed by GA (0.5 μmol/L). Furthermore, this anti-invasion effect of GA was associated with regulation of Snail. Snail expression was significantly down-regulated by treatment with GA (0.5 μmol/L) in the TNF-α-stimulated PC3 cells.Conclusion:GA inhibits TNF-α-induced invasion of PC3 cells via inactivation of the PI3K/Akt and NF-κB signaling pathways, which may offer a novel approach for the treatment of human prostate cancer.

Methyl jasmonate sensitizes human bladder cancer cells to gambogic acid-induced apoptosis through down-regulation of EZH2 expression by miR-101.

Gambogic acid (GA) and methyl jasmonate (MJ) are increasingly being recognized as novel natural anticancer compounds. Here, we investigated the antitumour effects of GA in combination with MJ on human bladder cancer cells.

BRD4 Regulates EZH2 Transcription through Upregulation of C-MYC and Represents a Novel Therapeutic Target in Bladder Cancer

People who develop bladder cancer frequently succumb to the intractable disease. Current treatment strategies are limited presumably due to the underlying molecular complexity and insufficient comprehension. Therefore, exploration of new therapeutic targets in bladder cancer remains necessary. Here, we identify that bromodomain-4 protein (BRD4), an important epigenome reader of bromodomain and extraterminal domain (BET) family member, is a key upstream regulator of enhancer of zeste homologue 2 (EZH2), and represents a novel therapeutic target in bladder cancer. We found that BRD4 was significantly overexpressed in bladder cancer cells and tissues. Inhibition of BRD4 decreased bladder cancer cell proliferation concomitantly with the accumulation of cell apoptosis in vitro and suppressed tumor growth in vivo. We further found that suppression of BRD4 decreased the mRNA and protein levels of EZH2, which was reversed by ectopic expression of C-MYC. In particular, individual silencing of BRD4 using shRNA or the BET inhibitor JQ1 strikingly diminished the recruitment of C-MYC to EZH2 promoter in bladder cancer. Briefly, our research reveals that BRD4 positively regulates EZH2 transcription through upregulation of C-MYC, and is a novel promising target for pharmacologic treatment in transcriptional program intervention against this intractable disease. Mol Cancer Ther; 15(5); 1029–42. ©2016 AACR.

Long non-coding RNA MEG3 induces renal cell carcinoma cells apoptosis by activating the mitochondrial pathway.

This study aimed to examine the effect of long non-coding RNA (LncRNA) MEG3 on the biological behaviors of renal cell carcinoma (RCC) cells 786-0 and the possible mechanism. MEG3 expression levels were detected by RT-qPCR in tumor tissues and adjacent non-tumor tissues from 29 RCC patients and in RCC lines 786-0 and SN12 and human embryonic kidney cell line 293T. Plasmids GV144-MEG3 (MEG3 overexpression plasmid) and GV144 (control plasmid) were stably transfected into 786-0 cells by using lipofectamine 2000. Cell viabilities were determined by MTT, cell apoptosis rates by flow cytometry following PE Annexin V and 7AAD staining, apoptosis-related protein expressions by Western blotting, and Bcl-2 mRNA by RT-qPCR in the transfected cells. The results showed that MEG3 was evidently downregulated in RCC tissues (P<0.05) and RCC cell lines (P<0.05). The viabilities of 786-0 cells were decreased significantly after transfection with GV144-MEG3 for over 24 h (P<0.05). Consistently, the apoptosis rate was significantly increased in 786-0 cells transfected with GV144-MEG3 for 48 h (P<0.05). Furthermore, overexpression of MEG3 could reduce the expression of Bcl-2 and procaspase-9 proteins, enhance the expression of cleaved caspase-9 protein, and promote the release of cytochrome c protein to cytoplasm (P<0.05). Additionally, Bcl-2 mRNA level was declined by MEG3 overexpression (P<0.05). It was concluded that MEG3 induces the apoptosis of RCC cells possibly by activating the mitochondrial pathway.SummaryThis study aimed to examine the effect of long non-coding RNA (LncRNA) MEG3 on the biological behaviors of renal cell carcinoma (RCC) cells 786-0 and the possible mechanism. MEG3 expression levels were detected by RT-qPCR in tumor tissues and adjacent non-tumor tissues from 29 RCC patients and in RCC lines 786-0 and SN12 and human embryonic kidney cell line 293T. Plasmids GV144-MEG3 (MEG3 overexpression plasmid) and GV144 (control plasmid) were stably transfected into 786-0 cells by using lipofectamine 2000. Cell viabilities were determined by MTT, cell apoptosis rates by flow cytometry following PE Annexin V and 7AAD staining, apoptosis-related protein expressions by Western blotting, and Bcl-2 mRNA by RT-qPCR in the transfected cells. The results showed that MEG3 was evidently downregulated in RCC tissues (P<0.05) and RCC cell lines (P<0.05). The viabilities of 786-0 cells were decreased significantly after transfection with GV144-MEG3 for over 24 h (P<0.05). Consistently, the apoptosis rate was significantly increased in 786-0 cells transfected with GV144-MEG3 for 48 h (P<0.05). Furthermore, overexpression of MEG3 could reduce the expression of Bcl-2 and procaspase-9 proteins, enhance the expression of cleaved caspase-9 protein, and promote the release of cytochrome c protein to cytoplasm (P<0.05). Additionally, Bcl-2 mRNA level was declined by MEG3 overexpression (P<0.05). It was concluded that MEG3 induces the apoptosis of RCC cells possibly by activating the mitochondrial pathway.

AN N-terminal Smac peptide sensitizes human prostate carcinoma cells to methyl jasmonate-induced apoptosis

Although the anti-cancer agent methyl jasmonate (MJ) has been shown to selectively target malignant cells while sparing normal ones, hormone-refractory prostate cancer cells are relatively resistant to MJ than other cancer cells. In the present study, we investigated the effect of cell permeable seven-residue peptide of Smac (SmacN7), an antagonist of the inhibitor of apoptosis proteins (IAPs), on MJ-induced apoptosis. SmacN7 significantly enhanced the growth inhibition effect of MJ in human prostate cancer cells, but not in proximal tubular epithelial cells. Moreover, SmacN7 sensitizes MJ-induced apoptosis through both caspase-9-dependent and -independent pathways. Thus, blockade of the over-expressed IAPs in cancer cells could yield a potential therapeutic benefit in jasmonates-based chemotherapy.

LncRNA GAS5 Inhibits Cellular Proliferation by Targeting P27Kip1

Recent studies have demonstrated that long noncoding RNAs (lncRNA) have important roles in cancer biology, and that the downregulation of lncRNA growth arrest–specific transcript 5 (GAS5) has been reported in a variety of human cancers. However, its role in prostate cancer is largely unknown. This study aims to investigate the biological role and underlying mechanism of GAS5 on proliferation in prostate cancer. The results demonstrate that GAS5 expression is significantly decreased in prostate cancer cells compared with prostate epithelial cells. Ectopic expression of GAS5 inhibited cell proliferation and induced a cell-cycle arrest in G0–G1 phase, whereas GAS5 knockdown promoted the G1–S phase transition. Subsequent analysis demonstrated that P27Kip1, a known regulator of cell cycle, was positively regulated by GAS5 and upregulation of GAS5 increased its promoter activity. E2F1, an important transcription factor, was shown to bind directly to and activate the P27Kip1 promoter. In addition, GAS5 interacted with E2F1 and enhanced the binding of E2F1 to the P27Kip1 promoter. Collectively, these findings determine that GAS5 functions as a tumor suppressor in prostate cancer development and progression via targeting P27Kip1. Implications: This study reveals a molecular pathway involving lncRNA GAS5/E2F1/P27Kip1 which regulates cell proliferation and could be a potential therapeutic target in prostate cancer. Mol Cancer Res; 15(7); 789–99. ©2017 AACR.

Overexpression of CircRNA BCRC4 regulates cell apoptosis and MicroRNA-101/EZH2 signaling in bladder cancer

SummaryEmerging evidence has indicated that circular RNAs (circRNAs) play pivotal roles in the regulation of cellular processes and are found to be aberrantly expressed in a variety of tumors. However, the clinical role of circRNAs in bladder cancer (BC) and the molecular mechanisms have yet to be fully understood. In this study, the clinical specimens were obtained and the expression level of a circRNA BCRC4 was detected by real-time PCR in both BC tissues and cell line. The circular RNA over-expression plasmid was constructed and transfected into BC cells and related cell line. The cell cycles and apoptosis were observed using inverted microscope and flow cytometry. Western blotting was used to compare the relative protein expression of groups with different treatments. It was found that circRNA BCRC4 expression was lower in BC tissues than in adjacent normal tissues. Furthermore, consequences of forced-expression of BCRC4 promoted apoptosis and inhibited viability of T24T and UMUC3 cells, and up-regulated BCRC4-increased miR-101 level, which suppressed EZH2 expression in both RNA and protein levels. In addition, gambogic acid (GA) is a promising natural anticancer compound for BC therapy, and GA treatment increased the BCRC4 expression in T24T and UMUC3 cells in a dose-dependent manner. Altogether, our findings suggest that BCRC4 functions as a tumor suppressor in BC, and mediates anticancer function, at least in part, by up-regulating the expression of miR-101. Targeting this newly identified circRNA may help us develop a novel strategy for treating human BC.Emerging evidence has indicated that circular RNAs (circRNAs) play pivotal roles in the regulation of cellular processes and are found to be aberrantly expressed in a variety of tumors. However, the clinical role of circRNAs in bladder cancer (BC) and the molecular mechanisms have yet to be fully understood. In this study, the clinical specimens were obtained and the expression level of a circRNA BCRC4 was detected by real-time PCR in both BC tissues and cell line. The circular RNA over-expression plasmid was constructed and transfected into BC cells and related cell line. The cell cycles and apoptosis were observed using inverted microscope and flow cytometry. Western blotting was used to compare the relative protein expression of groups with different treatments. It was found that circRNA BCRC4 expression was lower in BC tissues than in adjacent normal tissues. Furthermore, consequences of forced-expression of BCRC4 promoted apoptosis and inhibited viability of T24T and UMUC3 cells, and up-regulated BCRC4-increased miR-101 level, which suppressed EZH2 expression in both RNA and protein levels. In addition, gambogic acid (GA) is a promising natural anticancer compound for BC therapy, and GA treatment increased the BCRC4 expression in T24T and UMUC3 cells in a dose-dependent manner. Altogether, our findings suggest that BCRC4 functions as a tumor suppressor in BC, and mediates anticancer function, at least in part, by up-regulating the expression of miR-101. Targeting this newly identified circRNA may help us develop a novel strategy for treating human BC.

Predominant enhancement of apoptosis induced by methyl jasmonate in bladder cancer cells: therapeutic effect of the Antp-conjugated Smac peptide.

Methyl jasmonate (MJ) has recently attracted attention as a promising antitumoral compound because of its highly specific proapoptotic properties in a wide range of malignancies. However, the high doses required to achieve a therapeutic benefit have limited its clinical development. Here, we hypothesize that the family of inhibitor of apoptosis proteins (IAPs) may inhibit MJ-mediated apoptosis in cancer cells. We combined MJ with the IAPs inhibitor, the second mitochondria-derived activator of caspases (Smac) peptide to treat bladder cancer cells. The results showed that the combination of MJ and Smac peptide enhanced the apoptosis-inducing effect in a synergistic manner by releasing and activating IAPs-bounding caspase-3. These findings suggest that the inhibition of IAPs could overcome the resistance of cancer cells to MJ.