ACT001 inhibits tumor progression and reduces the expression of PD-L1 in non-small cell lung cancer

Abstract Purpose In recent years, remarkable advances in the therapeutic strategies for Non–small cell lung cancer (NSCLC) have revolutionized the treatment of NSCLC. However, in view of the low immune response, secondary drug resistance, autoimmune side effects, and financial burden of immunotherapy, developing novel immunotherapy or small-molecule compound is urged. Thus, this study investigates the effects of ACT001, a novel small-molecule inhibitor, on the antitumoral and immunomodulatory effects of ACT001 in NSCLC and explores the underlying mechanism. Methods The effects of ACT001 on NSCLC cells proliferation, clone formation, apoptosis, migration and invasion were measured using CCK8, clone formation, EDU stains, flow cytometry, transwell, and invasion assays, respectively. Flow cytometry was used to detect apoptosis of tumor cells and expression of granzyme B in CD3 + T cells in the co-culture system. Pull-down and mass spectrometry analysis were used to screen the interacting proteins of ACT001. Transcription factor binding sites were predicted by JASPAR database. Western blotting, rt-PCR, and flow cytometry were used to detect PD-L1, p-STAT1, and p-STAT3 expression in NSCLC cells exposed to ACT001. Results ACT001 inhibited the proliferation, migration, invasion and cell cycle progression of NSCLC cells, while promoted NSCLC cell apoptosis. ACT001 could decrease the expression of PD-L1 in NSCLC cells by inhibiting the phosphorylation of STAT1 and STAT3, which directly bind to the promoter of PD-L. Furthermore, ACT001 enhanced the release of granzyme B in CD3 + T cells, and promoted the apoptosis of NSCLC cells in the co-culture system. Conclusion We discovered that ACT001 exhibits a dual effect in NSCLC. On one hand, ACT001 has direct cytotoxicity on tumor cells in terms of inhibiting the proliferation, migration and invasion, and promoting NSCLC cell apoptosis. On the other hand, it also leads downregulation of PD-L1 in NSCLC cells to restore the anti-tumor ability of T cells. Our findings provide novel insights into the antitumoral and immunomodulatory effects of ACT001 which may shed new light on treatment of NSCLC.