In the present study, CuONPs effectively downregulated the expression of BCL2, while induced the expression of BAX. Current findings are in agreement with previous studies, which demonstrated that CuONPs inhibited cell growth and induced apoptosis in acute myeloid leukemia, breast, gastric, colon and lung cancer cells via significant induction of BAX and downregulation of BCL2 (Shafagh et al., 2015; Gopinath et al., 2016; Khan et al., 2017; Kalaiarasi et al., 2018). This evidence concerns the gene BAX and lung cancer.