Mingyue Tan

TGF-β–Induced Upregulation of malat1 Promotes Bladder Cancer Metastasis by Associating with suz12

Purpose: TGF-β promotes tumor invasion and metastasis by inducing an epithelial–mesenchymal transition (EMT). However, the underlying mechanisms causing this are not entirely clear. Long noncoding RNAs (lncRNA) have been shown to play important regulatory roles in cancer progression. The lncRNA malat1 (metastasis associated lung adenocarcinoma transcript 1) is a critical regulator of the metastasis phenotype of lung cancer cells. Experimental Design: We, therefore, investigated whether TGF-β regulates malat1 expression to promote tumor metastasis of bladder cancer. The expression levels of malat1 and EMT markers were assayed in specimens of bladder cancer. The role of malat1 in regulating bladder cancer metastasis was evaluated in cell and animal models. Results: TGF-β induces malat1 expression and EMT in bladder cancer cells. malat1 overexpression is significantly correlated with poor survival in patients with bladder cancer. malat1 and E-cadherin expression is negatively correlated in vitro and in vivo. malat1 knockdown inhibits TGF-β–induced EMT. malat1 is associated with suppressor of zeste 12 (suz12), and this association results in decrease of E-cadherin expression and increase of N-cadherin and fibronectin expression. Furthermore, targeted inhibition of malat1 or suz12 suppresses the migratory and invasive properties induced by TGF-β. Finally, we demonstrated that malat1 or suz12 knockdown inhibits tumor metastasis in animal models. Conclusion: These data suggest that malat1 is an important mediator of TGF-β–induced EMT, and suggest that malat1 inhibition may represent a promising therapeutic option for suppressing bladder cancer progression. Clin Cancer Res; 20(6); 1531–41. ©2014 AACR.

Long non-coding RNA UCA1 increases chemoresistance of bladder cancer cells by regulating Wnt signaling.

Chemotherapy is a reasonable alternative to cystectomy in patients with invasive and advanced bladder cancer. However, bladder cancer cells often develop drug resistance to these therapies, and ~ 50% of patients with advanced bladder cancer do not respond to chemotherapy. Recent studies have shown that long non‐coding RNA (lncRNA) is involved in the development of chemoresistance. Here we investigated the role of the urothelial cancer‐associated 1 (UCA1) lncRNA in cisplatin resistance during chemotherapy for bladder cancer. We showed that cisplatin‐based chemotherapy results in up‐regulation of UCA1 expression in patients with bladder cancer. Similarly, UCA1 levels are increased in cisplatin‐resistant bladder cancer cells. Over‐expression of UCA1 significantly increases the cell viability during cisplatin treatment, whereas UCA1 knockdown reduces the cell viability during cisplatin treatment. UCA1 inhibition also partially overcomes drug resistance in cisplatin‐resistant T24 cells. Furthermore, we showed that UCA1 positively regulates expression of wingless‐type MMTV integration site family member 6 (Wnt6) in human bladder cancer cell lines. UCA1 and Wnt6 expression is also positively correlated in vivo. Up‐regulation of UCA1 activates Wnt signaling in a Wnt6‐dependent manner. We finally demonstrate that UCA1 increases the cisplatin resistance of bladder cancer cells by enhancing the expression of Wnt6, and thus represents a potential target to overcome chemoresistance in bladder cancer.

SUMO-specific protease 2 suppresses cell migration and invasion through inhibiting the expression of MMP13 in bladder cancer cells.

Background: SUMO-specific protease 2 (SENP2) is a de-SUMOylation protease family member which has an indispensable role in the regulation of NF-κB transcriptional activation and Wnt signaling. However, whether SENP2 plays a role in tumor metastasis is completely unknown. Methods: Real-time PCR and Western blot was used to detect the expression of SENP2 in human bladder cancer samples and cell lines. Small interfering RNA (siRNA) was used to silencing the expression of SENP2. Matrigel-coated invasion chambers were used to detect the invasion ability of SENP2 in bladder cancer cells. Results: SENP2 was down-regulated in bladder cancer samples. SENP2 inhibited bladder cancer cells migration and invasion in vitro. Transcriptional analysis of several genes associated with tumor metastasis and invasion demonstrated that SENP2 selectively down-regulated MMP13 in bladder cancer cells. Further analysis indicated that silencing of MMP13 rescued the invasive phenotype in SENP2 expressing T24 cells. Conclusion: SENP2 functions as a tumor metastasis suppressor in bladder cancer. The effects of SENP2 on bladder cancer invasion are partially mediated by inhibiting the expression of MMP13.

The CXCL12 G801A polymorphism and cancer risk: Evidence from 17 case-control studies

CXCL12 has been implicated in human carcinogenesis, but the association between the most-studied G801A polymorphism (rs1801157) and the risk of various cancers was reported with inconclusive results. The aim of this study was to assess the association between the CXCL12 G801A polymorphism and cancer risk. A meta-analysis of 17 studies with 3048 cancer patients and 4522 controls was conducted to evaluate the strength of the association using odds ratio (OR) with its 95% confidence interval (CI). The overall results showed that the variant genotypes were associated with a significantly increased risk of all cancer types (OR=1.38, 95%CI=1.18-1.61 for GA versus GG, and OR=1.36, 95%CI=1.17-1.59 for GA/AA versus GG). In the stratified analyses, there was a significantly increased risk for the studies of breast cancer (OR=1.64, 95% CI=1.16-2.33 for AA versus GG, OR=1.42, 95%CI=1.18-1.71 for GA versus GG, and OR=1.44, 95%CI=1.21-1.72 for GA/AA versus GG) and lung cancer (OR=2.86, 95% CI=1.75-4.69 for AA versus GG, OR=1.62, 95% CI=1.20-2.18 for GA vs. GG, OR=1.80, 95% CI=1.36-2.39 for GA/AA versus GG, and OR=2.24, 95%CI=1.41-3.57 for AA versus GA/GG), which remained for the studies of Asian populations and hospital-based control sources. Although some modest bias could not be eliminated, this meta-analysis indicates that the CXCL12 G801A polymorphism is a low-penetrance risk factor for cancer development.

Upregulated SMYD3 promotes bladder cancer progression by targeting BCLAF1 and activating autophagy.

The recent discovery of a large number of histone methyltransferases reveals important roles of these enzymes in regulating tumor development and progression. SMYD3, a histone methyltransferase, is associated with poor prognosis of patients with prostate and gastric cancer. In the study, we attempted to investigate its putative oncogenic role on bladder cancer. Here, we report that SMYD3 frequently amplified in bladder cancer is correlated with bladder cancer progression and poor prognosis. Overexpression of SMYD3 promotes bladder cancer cell proliferation and invasion, whereas SMYD3 knockdown inhibits cancer cell growth and invasion. Mechanically, SMYD3 positively regulates the expression of BCL2-associated transcription factor 1 (BCLAF1). SMYD3 physically interacts with the promoter of BCLAF1 and upregulates its expression by accumulating di- and trimethylation of H3K4 at the BCLAF1 locus. We further show that SMYD3 overexpression in bladder cancer cells promotes autophagy activation, whereas BCLAF1 depletion inhibits SMYD3-induced autophagy. Finally, we demonstrate that SMYD3 promotes bladder cancer progression, at least in part by increasing BCLAF1 expression and activating autophagy. Our results establish a function for SMYD3 in autophagy activation and bladder cancer progression and suggest its candidacy as a new prognostic biomarker and target for clinical management of bladder cancer.

Downregulation of homeodomain-interacting protein kinase-2 contributes to bladder cancer metastasis by regulating Wnt signaling.

Homeodomain‐interacting protein kinase‐2 (Hipk2) has been shown to have important regulatory roles in cancer biology, such as cancer cell proliferation, cell cycle, and cell invasion. However, the contributions of Hipk2 to bladder cancer metastasis remain largely unknown. In the current study, we assayed the expression level of Hipk2 in bladder cancer tissues by real‐time PCR, and defined its biological functions. We found that Hipk2 levels were downregulated in most bladder cancer tissues compared with adjacent normal tissues, and Hipk2 levels were remarkably decreased in metastasized tumor tissues when compared with primary tumors. SiRNA‐mediated Hipk2 silencing increased bladder cancer cell invasion. Hipk2 knockdown resulted in decrease of E‐cadherin expression and increase of N‐cadherin and fibronectin expression, indicated that epithelial‐mesenchymal transition (EMT) was induced. We further demonstrated that Hipk2 knockdown induced Wnt signaling activation and β‐catenin nuclear localization. Finally, we confirmed that Hipk2 inhibition promoted EMT and subsequent cell invasion, at least in part by activating Wnt signaling. These data suggest an important role of Hipk2 in regulating metastasis of bladder cancer and implicate the potential application of Hipk2 in bladder cancer therapy. J. Cell. Biochem. 115: 1762–1767, 2014.

SENP2 regulates MMP13 expression in a bladder cancer cell line through SUMOylation of TBL1/TBLR1

Bladder cancer (BC) is the most popular malignant urinary cancer in China. BC has the highest incidence and mortality among all genitourinary system tumors. Although the early-stage BC could be treated with advanced electron flexible systourethroscope, early metastasis of the BC occur frequently, and often results in poor prognosis. Recently, we reported that small ubiquitin related modifier (SUMO)-specific protease 2 (SENP2) was downregulated in BC specimen. SENP2 appeared to inhibit migration and invasion of bladder cancer cells in vitro, through suppressing MMP13 in BC cells. However, the exact underlying mechanisms remain unknown. Here, we reported that SENP2 inhibited nuclear translocation of β-catenin, which targeted the promotor of MMP13 to activate MMP13 to enhance BC cell metastasis. WNT ligands induced TBL1/TBLR1 SUMOylation to form complexes with β-catenin to facilitate β-catenin nuclear translocation, which could be efficiently inhibited through suppression of SUMOylation of TBL1/TBLR1. Together, our data suggest that SENP2 inhibits MMP13 expression in BC cells through de-SUMOylation of TBL1/TBLR1, which inhibits nuclear translocation of β-catenin. Thus, SENP2 may be a promising therapeutic target for BC.

The platelet isoform of phosphofructokinase contributes to metabolic reprogramming and maintains cell proliferation in clear cell renal cell carcinoma

Metabolic alterations underlying clear cell renal cell carcinoma (ccRCC) progression include aerobic glycolysis, increased pentose phosphate pathway activity and reduced oxidative phosphorylation. Phosphofructokinase (PFK), a key enzyme of the glycolytic pathway, has L, M, and P isoforms with different tissue distributions. The mRNA level of the platelet isoform of phosphofructokinase (PFKP) is reported to be up-regulated in ccRCC patients. However, it remains unclear whether PFKP plays an important role in promoting aerobic glycolysis and macromolecular biosynthesis to support cell proliferation in ccRCC. Here we found that the up-regulated PFKP became the predominant isoform of PFK in human ccRCC. Suppression of PFKP not only impaired cell proliferation by inducing cell cycle arrest and apoptosis, but also led to decreased glycolysis, pentose phosphate pathway and nucleotide biosynthesis, accompanied by activated tricarboxylic acid cycle in ccRCC cells. Moreover, we found that p53 activation contributed to cell proliferation and metabolic defects induced by PFKP knockdown in ccRCC cells. Furthermore, suppression of PFKP led to reduced ccRCC tumor growth in vivo. Our data indicate that PFKP not only is required for metabolic reprogramming and maintaining cell proliferation, but also may provide us with a valid target for anti-renal cancer pharmaceutical agents.

Cisplatin inhibits the progression of bladder cancer by selectively depleting G-MDSCs: A novel chemoimmunomodulating strategy

Bladder cancer (BC) is a disease arising from the malignant cells of the urinary bladder. Myeloid-derived suppressor cells (MDSCs) expand broadly and have strong immunosuppressive activities in the cancer microenvironment. Determining how to inhibit the negative effects of MDSCs requires immediate attention. In this study, we found that granulocytic-MDSCs (G-MDSCs), which constitute one of the two types of MDSCs, were significantly increased in BC tissues compared with those in the adjacent bladder tissues. There was a robust negative correlation between the G-MDSCs and the CD8+ T cells in the BC tissues. In this study, we attempted to identify pharmacological approaches to eliminate MDSCs and restore T cell anti-tumor activities. It is necessary to explore a method to eliminate the detrimental effects of MDSCs. Cisplatin, a chemotherapy medication used to treat BC, not only rapidly kills proliferating cancer cells but also affects the tumor immune microenvironment. However, the mechanism underlying this phenomenon is largely unknown. In this study, we found that Cisplatin directly inhibited the proliferation and induced the apoptosis of T24 cells (a BC cell line), as well as decreased the percentage of the G-MDSCs in the population of peripheral blood mononuclear cells (PBMCs), which restored the expansion of the CD8+ T cells. In the C3H/He mouse BC model, Cisplatin treatment inhibited the progression of BC and effectively decreased the proportion of G-MDSCs. These results suggest that Cisplatin treatment enhances the anti-tumor function of CD8+ T cells by decreasing G-MDSCs. This finding provides a new perspective for Cisplatin treatment to prevent the progression of BC, particularly in patients with abnormally high levels of G-MDSCs.

Lysosomal acid lipase promotes cholesterol ester metabolism and drives clear cell renal cell carcinoma progression

Clear cell renal cell carcinoma (ccRCC) is characterized histologically by accumulation of cholesterol esters, cholesterol and other neutral lipids. Lysosomal acid lipase (LAL) is a critical enzyme involved in the cholesterol ester metabolism. Here, we sought to determine whether LAL could orchestrate metabolism of cholesterol esters in order to promote ccRCC progression.