p53-Regulated Long Noncoding RNA PRECSIT Promotes Progression of Cutaneous Squamous Cell Carcinoma via STAT3 Signaling.

Long noncoding RNAs (lncRNAs) have emerged as putative biomarkers and therapeutic targets in cancer. The role of lncRNA LINC00346 in cutaneous squamous carcinoma (cSCC) was examined. The expression of LINC00346 was up-regulated in cSCC cells compared with normal human epidermal keratinocytes. Elevated expression of LINC00346 was noted in tumor cells in cSCC tissue sections in vivo, as compared with cSCC in situ, and actinic keratosis by RNA in situ hybridization; and the expression in seborrheic keratosis and normal skin was very low. Immunohistochemical analysis of cSCC tissue sections and functional assays of cSCC cells in culture showed that LINC00346 expression is down-regulated by p53. Knockdown of LINC00346 inhibited invasion of cSCC cells in culture and suppressed growth of human cSCC xenografts in vivo. Knockdown of LINC00346 inhibited expression of activated STAT3 and resulted in down-regulation of the expression of matrix metalloproteinase (MMP)-1, MMP-3, MMP-10, and MMP-13. Based on these observations LINC00346 was named p53 regulated carcinoma-associated STAT3-activating long intergenic non-protein coding transcript (PRECSIT). These results identify PRECSIT as a new p53-regulated lncRNA, which promotes progression of cSCC via STAT3 signaling.