Silencing of the Smad nuclear interacting protein 1 (SNIP1) by siRNA inhibits proliferation and induces apoptosis in pituitary adenoma cells.

Smad nuclear interacting protein 1 (SNIP1) gene encodes a protein that contains a conservative C-terminal forkhead-associated domain and functions as a transcriptional coactivator to regulate cell proliferation and cancer progression. This study aimed to investigate the clinical and biological significance of SNIP1 expression in pituitary adenoma. We analyzed SNIP1 expressions in mouse fibroblast L929 cells and mouse pituitary adenoma AtT-20 cells by Western blotting. SNIP1 gene knockdown by small interfering RNA (siRNA) transfection was performed to evaluate SNIP1 function in pituitary adenoma cell lines. As expected, SNIP1 was found to be upregulated in pituitary adenoma cells. The mRNA and protein levels of SNIP1 were inhibited in AtT-20 cells transfected with siRNAs, which led to decreased proliferation, increased apoptosis, and cycle arrest of pituitary adenoma cells. Concomitantly, c-Myc and cyclin D1 protein levels were reduced. These findings may provide novel targets for the treatment of pituitary adenoma.