NOTCH1 functions as an oncogene by regulating the PTEN/PI3K/AKT pathway in clear cell renal cell carcinoma

Objectives: Although NOTCH1 plays a wide-ranging role in controlling cell fate, differentiation, and development, its pathologic roles in clear cell renal cell carcinoma (CCRCC) are still unclear. In the present study, the expression pattern of NOTCH1 was examined in CCRCC tissues, and the interaction of NOTCH1 with the phosphatase and tensin homologue deleted on chromosome 10 (PTEN)/phosphatidylinositol 3-kinase (PI3K)/AKT pathway was investigated in vitro. Materials and methods: Thirty-six paired CCRCC and adjacent non-neoplastic renal samples were analyzed by Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR). The alteration of NOTCH1, hairy and enhancer of split 1 (HES1), PTEN, AKT (phosphorylated at Ser473) in CCRCC cell line (786-O), and the human normal kidney tubule epithelial cell line (HKC) were analyzed by Western blotting and qRT-PCR, before and after transfection with siRNA against NOTCH1 or the plasmid containing the ORF clone of NOTCH. The effects of NOTCH1 signaling pathway on cells proliferation, apoptosis, invasion, and migration were detected by MTS assay, flow cytometry analyses, and transwell chamber assay, respectively. Results: The NOTCH1 expression levels were significantly increased in CCRCC tissues compared with the adjacent non-neoplastic renal samples, while it had no significant association with the pathologic parameters. NOTCH1 signaling cascade was constitutively active in human CCRCC cell lines. Blocking NOTCH1 signaling resulted in the attenuation of proliferation, invasion, and migration, as well as PTEN up-regulation with decreased AKT phosphorylation. NOTCH1 overexpression had an opposite effect to NOTCH1 knockdown. Conclusions: Our findings indicated that NOTCH1 receptor expression was up-regulated in CCRCC, and that NOTCH1 could regulate PTEN expression and the activity of the PI3K/AKT pathway via HES1 in 786-O and HKC cell lines. These might provide a basis for the designing new therapeutic strategies for CCRCC. (C) 2013 Elsevier Inc. All rights reserved.