Studying the Role of Autophagy in Cancer Cells: Exploring Novel Therapeutic Targets for Cancer Treatment

Abstract

Autophagy plays a dual role in cancer, acting as both a tumor suppressor and promoter depending on context. In this study, we quantified basal autophagy marker expression (LC3-II, p62) across five human cancer cell lines (A549, MCF-7, HeLa, PC3, HCT116) and evaluated the antitumor efficacy of a novel ULK1 inhibitor alone and in combination with chloroquine (CQ) and doxorubicin. HeLa cells exhibited the highest LC3-II (1.5 AU) and lowest ULK1 inhibitor IC₅₀ (1.8 µM), whereas HCT116 showed the lowest LC3-II (0.8 AU) and highest IC₅₀ (3.5 µM), indicating that elevated autophagic flux correlates with increased sensitivity to ULK1 blockade (r = –0.85). In MCF-7 cells, CQ monotherapy reduced viability from 100% to 10% at 40 µM, and combined CQ/doxorubicin treatment shifted cell death toward apoptosis (75%) versus necrosis (25%). Higher p62 levels correlated positively with IC₅₀ (r = 0.72), suggesting p62 as a predictive biomarker for inhibitor responsiveness. In vivo, ULK1 inhibitor administration (10 mg/kg, every other day for 21 days) in xenograft-bearing mice achieved tumor volume reductions of 20–40%, with HeLa-derived tumors most responsive. Statistical analyses confirmed significant differences among treatments (one-way ANOVA, p < 0.05). These data establish that cancer cells with high autophagic activity are particularly vulnerable to ULK1 inhibition and that autophagy blockade can potentiate chemotherapeutic cytotoxicity. Our findings support the use of LC3-II and p62 as stratification biomarkers and advocate for further clinical development of combination regimens targeting autophagy in precision oncology.