Dysregulation and epigenetic reprogramming of NRF2 signaling axis promote acquisition of cisplatin resistance and metastasis in Head and Neck Squamous Cell Carcinoma

PURPOSE: CDDP based chemotherapy is a first-line treatment for patients with advanced head and neck squamous cell carcinomas (HNSCCs), despite a high rate of treatment failures, acquired resistance and subsequent aggressive behavior. The purpose of this study was to delineate the mechanism of CDDP resistance and metastasis in HNSCC. We investigated the role of NRF2 pathway activation as a driven event for tumor progression and metastasis of HNSCC.

EXPERIMENTAL DESIGN: Human HNSCC cell lines that are highly resistant to CDDP were generated. Clonogenic survival assays and a mouse model of oral cancer were used to examine the impact of NRF-2 activation in vitro and in vivo on CDDP sensitivity and development of metastasis. Western blotting, immunostaining, whole exome sequencing, single cell transcriptomic and epigenomic profiling platforms were performed to dissect clonal evolution and molecular mechanisms Results: Implantation of CDDP resistant HNSCC cells into the tongues of nude mice resulted in a very high rate of distant metastases. The CDDP resistant cells had significantly higher expression of NRF2 pathway genes in the presence of newly acquired KEAP1 mutations, or via epigenomic activation of target genes. Knockdown of NRF2 or restoration of the wtKEAP1 genes re-sensitized resistant cells to CDDP and decreased distant metastasis. Finally, treatment with inhibitor of GLS1, a NRF2 target gene, alleviated CDDP resistance.

CONCLUSIONS: CDDP resistance and development of distant metastasis are associated with dysregulated and epigenetically reprogrammed KEAP1-NRF2 signaling pathway. A strategy targeting KEAP1/NRF2 pathway or glutamine metabolism deserves further clinical investigation in patients with CDDP resistant head and neck tumors.