Expression of hepaCAM inhibits bladder cancer cell proliferation via a Wnt/ß-catenin-dependent pathway in vitro and in vivo.

We previously established that hepatocyte cell adhesion molecule (hepaCAM), a typical structure of immunoglobulin (Ig)-like adhesion molecules, inhibited the proliferation and the progression of cultured human bladder cancer cells. As increasing evidence reveals that aberrant activation of canonical Wnt pathway is involved in the pathogenesis of bladder cancer, and ß-catenin serves as a pivotal molecule of Wnt pathway. Then, we explored whether the anti-proliferation effect of hepaCAM was associated with Wnt/ß-catenin pathway in human bladder cancer cells. The negative correlation between hepaCAM and ß-catenin in transitional cell carcinoma of bladder (TCCB) was found. Follow by, studied the effect of hepaCAM on the key elements of Wnt pathway. Here, Our researches showed that hepaCAM played a central role in modulating the Wnt/ß-catenin signaling pathway by interfering nuclear protein levels of ß-catenin, leading to down-regulate transcriptional activity of LEF/TCF and its target genes c-Myc and cyclinD1. Mechanistically, we demonstrated that hepaCAM-activated GSK3ß led to elevate the phosphorylation of ß-catenin, contributing to the aberrant translocation of ß-catenin. In addition, Anti-proliferation and associated molecular mechanisms of hepaCAM were demonstrated by using vivo experiment. In conclusion, our reports uncover that expression of hepaCAM suppresses the proliferation of bladder cancer cells through a Wnt/ß-catenin-dependent signaling pathway in vitro and in vivo.

Nuclear factor-κB signaling pathway is involved in phospholipase Cε-regulated proliferation in human renal cell carcinoma cells.

Phospholipase Cε (PLCε), a downstream effector of small GTPase superfamily, has been identified to play a crucial role in tumorigenesis. Previously, our studies have showed that PLCε promotes proliferation of renal cell carcinoma (RCC) cells. However, the molecular mechanisms by which PLCε enhances the survival phenotype of RCC cells are still not fully instructed. In the present study, we first demonstrated that PLCε was highly expressed and had a close correlation with Ki67 protein expression in RCC tissue samples. Further, we found that downregulation of PLCε expression repressed growth and induced apoptosis in RCC cells. In addition, we reported a mechanism by which knockdown of PLCε gene potently suppressed the nuclear factor kappa (NF-κB) signaling pathway through action on inhibitor of κB kinase. Moreover, silencing PLCε gene decreased vascular endothelial growth factor (VEGF) expression, which was a downstream growth factor of NF-κB signaling pathway. Finally, downregulation of VEGF was severely enhanced by treatment cells with NF-κB specific inhibitor BAY11-7028 in PLCε knockdown cells. Taken together, these findings suggest that PLCε promotes RCC cell growth via NF-κB-mediated upregulation of VEGF.

A new PKCα/ß/TBX3/E-cadherin pathway is involved in PLCε-regulated invasion and migration in human bladder cancer cells.

Although PLCε has been verified to enhance bladder cancer cell invasion, the signaling pathways responsible for this remain elusive. Protein kinase C (PKCα/ß), which is involved in cancer development and progression, has been demonstrated to be activated by PLCε. However, the roles of PKCα/ß in PLCε-mediated bladder carcinoma cell invasion and migration have not been clearly identified. In this study, to determine what role PKCα/ß plays in PLCε-mediated bladder cancer cell invasion and migration, we silenced PLCε gene by adenovirus-shPLCε in T24 and BIU-87 cells and then revealed that it significantly inhibited cell migration and invasion. Further research indicated that cell bio-function of PLCε-regulated was related with PKCα/ß activity. These in vitro findings were supported by data from bladder carcinoma patient samples. In 35 case bladder cancer tumor samples, PLCε-overexpressing tumors showed significantly higher positive rates of PKCα/ß membrane immunohistochemistry staining than PLCε-low-expressing tumors. Mechanistically, study further showed that PLCε knockdown gene induced E-cadherin expression and decreased TBX3 expression, both of which were dependent on PKCα/ß activity. In addition, we demonstrated that treatment cells with TBX3-specific shorting hairpin RNA (shRNA) up-regulated E-cadherin expression and inhibited cell invasion/migration. Moreover, in in vivo experiment, immunohistochemistry analysis of Ad-shPLCε-infected tumor tissue showed low expression levels of phospho-PKCα/ß and TBX3 and high expression levels of E-cadherin compared with those of the control group. In summary, our findings uncover that PKCα/ß is critical for PLCε-mediated cancer cell invasion and migration and provide valuable insights for current and future Ad-shPLCε and PKCα/ß clinical trials.