Abstract
Sunitinib, a tyrosine kinase inhibitor, is among the first‑line treatments for metastatic or advanced stage renal cell carcinoma (RCC). However, patients with RCC develop resistance to sunitinib. We have previously demonstrated that lysosome‑associated membrane protein 2 (LAMP‑2), which has three splice variants with different functions (LAMP‑2A, LAMP‑2B, and LAMP‑2C), is involved in RCC. In the present study, we examined which splice variants of LAMP‑2 contributed to sunitinib resistance in RCC cells. In vitro analysis using ACHN, human RCC cell line, revealed that the IC50 of sunitinib was significantly increased by overexpression of LAMP‑2A and LAMP‑2B, but not LAMP‑2C (P<0.01). Kaplan‑Meier survival analysis using clinical samples revealed an association between shorter survival and high expression of LAMP‑2A and LAMP‑2B, but not LAMP‑2C, in patients with RCC treated with sunitinib (P=0.01). Furthermore, high expression of LAMP‑2A and LAMP‑2B in RCC revealed a weak to moderate inverse correlation with the tumor shrinkage rate and progression‑free survival, respectively. Thus, high expression of LAMP‑2A and LAMP‑2B contributed to the acquisition of sunitinib resistance, indicating that the expression of these two variants can predict the efficacy of sunitinib treatment in patients with RCC.