DUSP1 and SOX2 expression determine Squamous cell carcinoma of the salivary gland progression.

Salivary gland squamous cell carcinomas (SG-SCCs) are a rare type of head and neck cancers which are linked to poor prognosis. Due to their low frequencies, the molecular mechanisms responsible for their aggressiveness are poorly understood. In this work we studied the function of the phosphatase DUSP1, a negative regulator of MAPK activity, in controlling the progression of SG-SCCs. We generated DUSP1 KO clones in A253 human cells. These clones showed a reduced ability to grow in 2D, self-renew in ECM matrices and grow tumors in immunodeficient mice. This was caused by an overactivation of the stress and apoptosis kinase JNK1/2 in DUSP1-KO clones. Interestingly, RNAseq analysis revealed that the expression of SOX2, a well know self-renewal gene was decreased at the mRNA and protein level. Unexpectedly, CRISPR-KO of SOX2 did not recapitulate DUSP1-KO phenotype, and SOX2-null cells had an enhanced ability to self-renew and grow tumors in mice. Gene expression analysis demonstrated that SOX2-null cells have a decreased squamous differentiation profile -losing TP63 expression- and an increased migratory phenotype, with an enhanced epithelial to mesenchymal transition signature. In summary, our data indicates that DUSP1 and SOX2 have opposite functions in SG-SCC, being DUSP1 necessary for tumor growth and SOX2 dispensable, and with a tumor suppressor function. Our data will suggest that the expression SOX2 and DUSP1 could be a useful biomarker to predict the progression of patients with SG-SCCs.