L-tetrahydropalmatine attenuates cisplatin-induced nephrotoxicity via selective inhibition of organic cation transporter 2 without impairing its antitumor efficacy.

Cisplatin is a first-line chemotherapeutic agent that is widely used for treatment of various solid tumors. However, cisplatin-induced adverse effects, particularly severe nephrotoxicity, preclude its application. In this study, we showed that L-tetrahydropalmatine (L-THP) could selectively inhibit organic cation transporter 2 (OCT2), which plays a crucial role in renal cisplatin uptake from the circulation. Additionally, we demonstrated that L-THP attenuated cisplatin-induced toxicity in mouse primary renal tubular cells. Subsequently, we verified that L-THP reduced the renal accumulation of cisplatin and alleviated cisplatin-induced renal injury in healthy and tumor-bearing nude mice. In healthy mice, co-treatment of L-THP at 5-40 mg/kg reduced cisplatin renal accumulation to 75.0%-49.9% of that in cisplatin alone group (10 mg/kg), and alleviated cisplatin-induced nephrotoxicity. Additionally, it did not alter Pt concentration in the tumor tissue and did not impair its antitumor efficacy in tumor bearing nude mice. The tumor inhibitory rates of cisplatin (10 mg/kg) co-treated with L-THP at 10, 20 and 40 mg/kg were 71.4%, 70.4% and 69.4%, respectively, in H460 tumor bearing nude mice, higher than that of in cisplatin alone group (60.6%), while in HCT116 tumor bearing nude mice, the tumor inhibitory rates in co-treated with 20 mg/kg L-THP was 34.7% (vs 26.3% in cisplatin alone group). Moreover, L-THP reduced cisplatin accumulation and alleviated cisplatin-induced cytotoxicity in human primary renal tubular cells. Therefore, our findings suggested that concomitant administration of L-THP could attenuate cisplatin-induced renal injury via selective inhibition of OCT2 without impairing its antitumor efficacy.