Silence of S1 RNA binding domain 1 represses cell growth and promotes apoptosis in human non-small cell lung cancer cells.

To investigate the expression of S1 RNA binding domain 1 (SRBD1) in non-small cell lung cancer tissue and the effects of SRBD1 silencing on the biological behaviors of human non-small cell lung cancer cells, and to explore the molecular mechanism of SRBD1functions in human non-small cell lung cancer cells. Expressions of SRBD1 in human non-small cell lung cancer tissues and cell lines were examined by immunostaining and RT-PCR. shRNAs of SRBD1 were chemically synthesized and transfected into A549 and NCI-H1299 cells by lentivirus. Cell proliferation was assayed by cell counting, MTT and clone formation. Cell apoptosis was assayed by flow cytometry. Tumorigenicity was assessed by cell injection into BALB/c athymic nude mouse. Gene chip analysis was employed to explore genomic changes in A549 cells. Potential classical signaling pathways, upstream regulators and gene interaction networks were analyzed by Ingenuity Pathway Analysis, and verified by western blot analysis. SRBD1 was specifically expressed in human squamous cell carcinoma and highly expressed in lung cancer cell lines, NCI-H1299, A549 and NCI-H1975. SRBD1 directed-shRNA (shSRBD1) effectively reduced the expression of SRBD1 in A549 and NCI-H1299 cells. SRBD1 silencing inhibited cell proliferation, and promoted cell apoptosis in non-small cell lung cancer cells, and suppressed tumorigenesis in a nude mouse model. In addition, we found silencing of SRBD1 expression resulted in marked changes in gene expression in A549 cells. Besides, in shSRBD1 group, the protein levels of EPS 15, IGF1R, MYC, PYCR1 and HNRNPA0 were downregulated, and the expressions of several classical factors involved in the growth and apoptosis of cancer cells were also decreased. We found that SRBD1 were specifically expressed in non-small cell lung cancer tissue. Silencing of SRBD1 inhibits cell growth and promotes cell apoptosis in non-small cell lung cancer cells, and suppresses tumorigenesis in vivo, suggesting that SRBD1 may be a new diagnostic indicator and therapeutic target of non-small cell lung cancer.