Abstract: Objective To study the expression of apurinic aprimidinic endonuclease 1 (APE1) and the relationship between the expression of APE1 and the sensitivity of platinum chemotherapy for NSCLC. Methods From January 2018 to June 2019, 136 NSCLC patients with stage Ⅲ B or Ⅳ plus non driving gene mutation were selected to extract and identify the plasma exosome APE1. Western blot and ELISA were used to detect the expression of APE1 in exosomes. Immunohistochemistry was used to detect the expression of APE1 in tissues. According to the response evaluation criteria in solid tumors, the patients were divided into two groups: the effective group and the ineffective group. The relationship between APE1 expression and drug sensitivity was examined. Results APE1 was mainly located within exosomes in peripheral blood. The level of APE1 in the exosomes of NSCLC patients was significantly higher than that of normal controls (P＜ 0.001). Compared with NSCLC patients with low tissue APE1 expression, patients with high tissue APE1 expression showed a significantly higher plasma APE1 level (P＜ 0.01). The APE1 level of exosomes in the chemotherapy ineffective group was significantly higher than that in the chemotherapy effective group (P＜ 0.001). Conclusions Exosomal APE1 can be used as a sensitive indicator to evaluate the response of patients to chemotherapy with platinum.

Key words: non small cell lung cancer, exosome, APE1, drug resistance