OBJECTIVE  To investigate the effects of Pingwei capsule(PWJN) medicated serum on N-methyl-N'-nitro-N-nitrosoguanidine(MNNG)-induced human gastric mucosal epithelial cells(GES-1) injury and Kelch-like epichlorohydrin-related protein 1(Keap1)-nuclear factor E2-related factor 2(Nrf2)/antioxidant response element(ARE) pathway.

METHODS  The GES-1 cells 2×10⁻⁵ mol·L⁻¹ MNNG to establish a MC cell model. The expression of proliferating cell-associated antigen(Ki67) and phosphatase and tensin homolog(PTEN) recombinant protein was detected to model evaluate the MC model. The optimal intervention concentration and time of PWJN-containing serum and Nrf2 inhibitor(ML385) were screened by CCK-8 assay. The cells were divided into 6 groups: normal group, model group, blank serum group, PWJN group, ML385 group, PWJN+ML385 group; Keap1, Nrf2, quinone oxidoreductase(NQO1) and glutathione S-transferase(GST) were detected by RT-qPCR. The protein expression levels of Keap1, Nrf2, NQO1 and GST were detected by Western blotting. The concentration of PTEN in cells was detected by ELISA. The co-expression levels of Nrf2 and Ki67 in each group were detected by immunofluorescence staining. The effect of PWJN on the proliferation and division of MC cells was detected by carboxyfluorescein diacetate succinimidyl ester cell proliferation assay.

RESULTS  The most suitable condition for PWJN-containing serum was 5.8% intervention for 48 h, and the most suitable condition for ML385 was 12.5 μmol·L⁻¹ intervention for 24 h. Compared with the normal group, the expression levels of Nrf2, NQO1, GST mRNA and protein, and cell proliferation rate in the model group and the blank serum group were significantly increased(P<0.01), the expression levels of Keap1 and PTEN were significantly decreased(P<0.01). Compared with the blank serum group, there was no significant difference in the expression of Keap1, Nrf2, NQO1, GST mRNA and protein, PTEN expression and cell proliferation rate in the model group. Compared with the blank serum group, the expression levels of Nrf2, NQO1, GST protein and mRNA and cell proliferation rate in the PWJN group were significantly decreased(P<0.01), and the expression levels of Keap1 and PTEN were significantly increased(P<0.01). Compared with ML385 group, the expression levels of Nrf2, NQO1 and GST mRNA and protein in PWJN+ML385 group were significantly decreased(P<0.01), and the expression levels of Keap1 and PTEN were significantly increased(P<0.01).

CONCLUSION  PWJN can reduce the transcriptional activity of Nrf2 and downstream overexpression factors by regulating Keap1/Nrf2/ARE signaling pathway, thereby closing the Nrf2 pathway and achieving normal oxidation-antioxidation balance, which may be one of the mechanisms for the treatment of gastric precancerous lesions.