Up-regulation of ABCG2 promotes cell proliferation in renal cell carcinoma and associate with clinicopathologic features

ABCG2, also known as breast cancer resistance protein (BCRP) is a drug efflux pump and an important member of the ATP-binding cassette transporter superfamily. Recent studies showed that ABCG2 play an important role in tumor progression. However, the role of ABCG2 in human renal cell carcinoma (RCC) remains largely unclear. In the present study, our data showed that elevated ABCG2 expression were observed in RCC tissues compared to adjacent non-tumor tissues, showing a high correlation with advanced clinical stage, elevated tumor stage, lymph node metastasis and lowered overall survival rates. Multivariate analysis revealed that ABCG2 expression was also an independent prognostic factor for comparison of clinical stage, tumor stage and lymph node metastasis. Furthermore, in vitro assays, we found that ABCG2 expression was lower in poorly-differentiated Caki-1 cells compare to well-differentiated 786-O cells. By respectively up-regulating or depleting ABCG2 expression in RCC cells, our finding suggested that ABCG2 could act as a promotor of RCC cell proliferation and cell apoptosis resistance. Thus, our data demonstrate that ABCG2 is a novel molecule involved in both RCC progression and prognosis. Full elucidation of ABCG2 functionality may supply a potential novel therapeutic agent for the treatment of RCC.