PKCε inhibits isolation and stemness of side population cells via the suppression of ABCB1 transporter and PI3K/Akt, MAPK/ERK signaling in renal cell carcinoma cell line 769P.

Protein kinase C epsilon (PKCε), a member of the novel PKC family, is known to be a transforming oncogene and tumor biomarker for many human solid cancers including renal cell carcinoma (RCC). We isolated side population (SP) cells from the RCC 769P cell line, and proved that those cells possess cancer stem cell (CSC) characteristics.

In this study, to identify the function of PKCε in cancer stemness of 769P SP cells, we reduced the expression of PKCε in those cells, following the results demonstrated that PKCε depletion had a negative correlation with the existence of SP cells in 769P cell line. Down-regulation of PKCε also suppresses the CSC potential of sorted 769P SP cells in several ways: proliferation potential, resistance to chemotherapeutics and in vivo tumor formation ability. Our study also reveals that PKCε is associated with ABCB1and this association probably contributed to the SP cells isolation from 769P cell line. Furthermore, the expression of ABCB1 is directly regulated by PKCε. Additionally, after the depletion of PKCε, the phosphorylation of pAkt, pStat3 and pERK was apparently suppressed in 769P SP cells, whereas PKCε overexpression could promote the phosphorylation of AKT, STAT3 and ERK in 769P Non-SP cells. Overall, PKCε down-regulation suppresses sorting and the cancer stem-like phenotype of RCC 769P SP cells through the regulation of ABCB1 transporter and the PI3K/Akt, Stat3 and MAPK/ERK pathways that are dependent on the phosphorylation effects. Thus, PKCε may work as an important mediator in cancer stem cell pathogenesis of renal cell cancer.

Cancer letters. 2016 Mar 29 [Epub ahead of print]

Bin Huang, Shun Jun Fu, Wen Zhe Fan, Zhong Hua Wang, Ze Bin Chen, Sheng Jie Guo, Jun Xing Chen, Shao Peng Qiu

Department of Urology, the First Affiliated Hospital, Sun Yat-Sen University, No. 58 Zhong Shan 2nd Road, Guangzhou 510080, China., Organ Transplant Center, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China., Department of Interventional Oncology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China., Department of Intensive Care Unit, Guangdong Provincial Institute of Geriatric Medicine, Guangdong General Hospital & Guangdong Academy of Medical Sciences, Guangzhou 510080, China., Department of Urology, the First Affiliated Hospital, Sun Yat-Sen University, No. 58 Zhong Shan 2nd Road, Guangzhou 510080, China., Department of Urology, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China., Department of Urology, the First Affiliated Hospital, Sun Yat-Sen University, No. 58 Zhong Shan 2nd Road, Guangzhou 510080, China.  Department of Urology, the First Affiliated Hospital, Sun Yat-Sen University, No. 58 Zhong Shan 2nd Road, Guangzhou 510080, China.  

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