INTRODUCTION: Gastric cancer has emerged as one of the major diseases threatening human health. Our previous studies indicated that the anti-cancer bioactive peptide (ACBP) inhibits the initiation and progression of gastric cancer through apoptosis and cell cycle arrest, yet the mechanisms remain unclear. To elucidate the relationships between the effects of ACBP and the levels of cell differentiation, as well as the functional mechanisms of ACBP, we conducted a study using three human gastric cancer cell lines: NCI-N87, MGC-803, and another unspecified line. METHOD: We investigated the impact of ACBP on the survival and morphology of these cancer cell lines, examined apoptosis and cell cycle progression, and detected the expression of TP53, TP63, and TP73 in cancer cells, as well as the expression of Bax, PUMA, and Mcl-1 in a xenograft mouse model. ACBP inhibited the proliferation of all three cancer cell lines in a dose-dependent manner, similar to the positive control and 5-fluorouracil (5-FU). The effect of ACBP correlated with the degree of differentiation of the cancer cells
the lower the differentiation degree, the stronger the inhibitory effect. RESULT: After ACBP treatment, the expression of TP53, TP63, and TP73 increased in all cell lines. In the xenograft mouse model, ACBP inhibited the growth of MGC-803 cells in vivo. The apoptotic- related genes Bax and PUMA were upregulated, while Mcl-1 was downregulated. ACBP inhibited tumor cell growth by inducing apoptosis through the TP53 signaling cascade, upregulating TP53, TP63, and TP73 and their downstream apoptosis-promoting genes Bax and PUMA while downregulating the anti-apoptotic gene Mcl-1. CONCLUSION: Notably, after ACBP treatment, Mcl-1 expression was significantly reduced in the tumor tissue of the xenograft model, indicating that ACBP induced apoptosis through the TP53 signaling cascade. This project provides a scientific basis for exploring the antitumor mechanism of ACBP in gastric cancer therapy.