Bioinformatic Analysis of Transcriptome Changes Underlying Metformin-induced Reversal of Drug Resistance in Head and Neck Squamous Cell Carcinoma Cells

Background: Metformin is the first-line drug for type II diabetes, and recent studies indicate that metformin plays an inhibitory role in multiple cancers. Metformin can also enhance the effect of chemotherapy. Although head and neck squamous cell carcinoma cells are sensitive to metformin, the mechanisms related to the metformin response and the chemosensitization effect have not been fully studied. Results: In this study, we aimed to elucidate the molecular mechanisms of metformin in HNSCC by transcriptome analysis and to reveal the underlying mechanisms of the sensitizing effects of metformin by combined online dataset analysis. mRNA sequencing and functional analysis of HNSCC samples after metformin treatment and functional analysis of mRNAs with opposite metformin-induced effects in chemosensitive versus chemoresistant cells revealed the molecular pathways, mainly the base excision repair pathway, by which this small molecule drug sensitizes HNSCC cells to treatment. Conclusions: These findings indicate that metformin exerts a hypersensitization effect by regulating the BER pathway in tumour cells, reducing their self-repair capacity after chemotherapy-induced DNA damage. In addition, the genes identified by transcriptome analysis are candidates for further investigation into the effector targets of metformin in the inhibition of HNSCC and could be applied to improve the treatment in HNSCC patients who develop resistance after advanced chemotherapy.