2529 - Targeting Glucose Transporter Networks to Overcome Radioresistance in Hepatocellular Carcinoma through Cancer Stemness and Autophagy Regulation

Purpose/Objective(s):

Radioresistance remains a major barrier to durable tumor control in hepatocellular carcinoma (HCC). Emerging evidence suggests that metabolic reprogramming supports cancer stem cell (CSC) survival and adaptive stress responses; however, the mechanistic integration between glucose transport, CSC programming, and autophagy in radioresistant HCC remains poorly defined. We investigated whether targeting glucose transporter networks could disrupt CSC maintenance and autophagy-mediated survival to overcome radioresistance.

Materials/Methods:

Parental Huh7 HCC cells and radioresistant derivatives (Huh7-IR) were analyzed for glucose transporter expression, cancer stem cell (CSC) markers, mitochondrial function, and autophagy signaling. Cells were treated with SGLT2 inhibitors (canagliflozin, dapagliflozin) and a GLUT inhibitor with or without irradiation. Functional assays included glucose uptake, clonogenic survival, tumorsphere formation, side-population analysis, ROS production, and mitochondrial membrane potential. Lentiviral shRNA knockdown of CD133, CD44, SQSTM1/p62, and LC3B was performed to define regulatory hierarchy.

Results:

Huh7-IR cells showed coordinated upregulation of SGLT2, GLUT1, and GLUT3 with enrichment of CSC features (CD133/CD44/ABCB1 and expanded side-population) and elevated basal autophagy markers. Glucose-transport inhibition suppressed tumorsphere formation and clonogenic capacity in both parental and Huh7-IR cells and remodeled stress-response signaling after irradiation. Mechanistically, CD133 knockdown markedly decreased CD44 and ABCB1, identifying CD133 as an upstream node supporting stemness and drug-efflux phenotype. In contrast, CD44 knockdown did not reduce CD133 but induced compensatory ABCB1 upregulation. CSC perturbation reprogrammed transporter usage: CD133 knockdown reduced GLUT3 and increased SGLT2, whereas CD44 knockdown increased SGLT2 and GLUT3, consistent with metabolic compensation. Notably, silencing either CD133 or CD44 caused a profound collapse of SQSTM1/p62 and LC3B (I/II), indicating that heightened basal autophagy in radioresistant HCC is dependent on an intact CSC program rather than acting as an independent parallel survival pathway.

Conclusion:

HCC radioresistance is maintained by an integrated CSC-regulated glucose transporter–autophagy axis that coordinates metabolic flexibility, mitochondrial stress tolerance, and survival. Targeting glucose transporters—particularly with clinically available SGLT2 inhibitors—simultaneously disrupts CSC maintenance and adaptive autophagy, providing a rational radiosensitization strategy. These findings establish metabolic-stemness coupling as a central driver of radiotherapy resistance and a highly translatable therapeutic vulnerability in HCC.