PD-1/PD-L1 Interaction Regulates BCL2, KI67, BAX, and CASP3, Altering Proliferation, Survival, and Apoptosis in Acute Myeloid Leukemia.

Programmed death ligand‑1 (PD‑L1) is a pivotal inhibitory checkpoint ligand known to induce T-cell exhaustion via interaction with the programmed death‑1 (PD‑1) receptor. Beyond this, PD-L1's intrinsic signaling pathways within cancer cells warrant further exploration. This study aims to elucidate the effect of PD-L1 stimulation on the proliferation, survival, and apoptosis of acute myeloid leukemia (AML) cell lines. Two human AML cell lines, HL-60 and THP-1 were cultured and treated with phorbol 12-myristate 13-acetate (PMA) to induce PD-L1overexpression. Post-treatment PD-L1 expression was confirmed via flow cytometry. Subsequently, cell surface PD-L1 was stimulated using a recombinant PD-1, 24 hours post-PMA treatment. The expression alterations in pivotal genes including BCL2, MKI67, BAX, and CASP3 were monitored using quantitative real-time polymerase chain reaction 24 and 48 hours post-treatment. Additionally, annexin-V through flow cytometry. Findings reveal that PD-L1 stimulation augments AML cell proliferation and survival by enhancing MKI67 and BCL2 expressions while concurrently inhibiting cell apoptosis due to decreased BAX and CASP3 expression following PD-L1 stimulation. Notably, stimulated cells expressed exhibited reduced annexin-V compared to control cells. This study underscores that PD-L1 stimulation fosters AML cell proliferation and survival while impeding cell apoptosis. The results hold potential implications for targeting PD-L1 in AML treatment strategies.