ASAP3 expression in non-small cell lung cancer: association with cancer development and patients' clinical outcome.

ASAP3 belongs to Arf-specific GTPase-activating proteins which regulate Arfs by stimulating their intrinsic GTP hydrolysis. ASAP3 expression and the clinical significance in malignant tumors are largely unknown. In this study, we examined ASAP3 expression in non-small cell lung cancer (NSCLC) to find out its clinicopathological significance. Immunohistochemistry shows elevated expression of ASAP3 in cancer tissues (54.8 % (57/104)) compared to normal lung tissues (18.0 % (9/50)) (p < 0.05). Increased ASAP3 expression was associated with poor differentiation, lymph node metastasis, and advanced TNM stages in NSCLC (p < 0.05). Survival analysis reveals that ASAP3 expression contributes to patients' poor clinical outcome (p < 0.05). We also examined ASAP3 expression in several lung cancer cell lines using Western blotting. We downregulated ASAP3 expression in LTE cell which has a relative high level of ASAP3 expression using siRNA and found that reduced ASAP3 leads to significant inhibition of cancer cell invasion (p < 0.05). These data indicate that ASAP3 is elevated in NSCLC and may contribute to cancer development and patients' poor clinical outcome, which is possibly due to its critical roles in regulating cancer invasion.