Over-expression of USP15/MMP3 predict poor prognosis and promote growth, migration in non-small cell lung cancer cells.

Aberrant ubiquitin modifications caused by an imbalance in the activities of ubiquitinases and de-ubiquitinases are emerging as important mechanisms underlying non-small cell lung cancer (NSCLC) progression. The deubiquitinating enzyme ubiquitin-specific peptidase 15 (USP15) has been identified as an important factor in oncogenesis and a potential therapeutic target. However, the expression profile and function of USP15 in NSCLC remain elusive. In the present study, we investigated the expression pattern and the potential biological functions of USP15 in NSCLC both in cells and animal models. Our data revealed that USP15 was highly expressed in NSCLC tissues and cells compared with normal counterpart. We subsequently knocked down USP15 expression in two NSCLC cell lines, which significantly suppressed cell proliferation. In addition, knocking down USP15 expression reduced NSCLC cell migration and invasion according to the results from Matrigel-Transwell analysis. NSCLC animal model results showed that USP15 knockdown also reduced NSCLC size. Biochemical analysis revealed that USP15 knockdown inhibited matrix metalloproteinase (MMP)3 and MMP9 expression. Furthermore, high levels of USP15 and MMP3 expression were associated with poor prognosis in NSCLC. In conclusion, the results from the present study suggest that the high expression of USP15 promotes NSCLC tumorigenesis. Therefore, it is proposed that USP15 and MMPs may represent novel biomarkers for NSCLC progression and prognosis.