PDIA3 modulates genomic response to 1,25-dihydroxyvitamin Din squamous cell carcinoma of the skin.

An active form of vitamin D(1,25-dihydroxyvitamin D) acts through vitamin D receptor (VDR) initiating genomic response, but several studies described also non-genomic actions of 1,25-dihydroxyvitamin D, implying the role of PDIA3 in the process. PDIA3 is a membrane-associated disulfide isomerase involved in disulfide bond formation, protein folding, and remodeling. Here, we used a transcriptome-based approach to identify changes in expression profiles in PDIA3-deficient squamous cell carcinoma line A431 after 1,25-dihydroxyvitamin Dtreatment. PDIA3 knockout led to changes in the expression of more than 2000 genes and modulated proliferation, cell cycle, and mobility of cells; suggesting an important regulatory role of PDIA3. PDIA3-deficient cells showed increased sensitivity to 1,25-dihydroxyvitamin D, which led to decrease migration. 1,25-dihydroxyvitamin Dtreatment altered also genes expression profile of A431ΔPDIA3 in comparison to A431WT cells, indicating the existence of PDIA3-dependent genes. Interestingly, classic targets of VDR, including CAMP (Cathelicidin Antimicrobial Peptide), TRPV6 (Transient Receptor Potential Cation Channel Subfamily V Member 6), were regulated differently by 1,25-dihydroxyvitamin D, in A431ΔPDIA3. Deletion of PDIA3 impaired 1,25-dihydroxyvitamin D-response of genes, such as PTGS2, MMP12, and FOCAD, which were identified as PDIA3-dependent. Additionally, response to 1,25-dihydroxyvitamin Din cancerous A431 cells differed from immortalized HaCaT keratinocytes, used as non-cancerous control. Finally, silencing of PDIA3 and 1,25-dihydroxyvitamin D, at least partially reverse the expression of cancer-related genes in A431 cells, thus targeting PDIA3 and use of 1,25-dihydroxyvitamin Dcould be considered in a prevention and therapy of the skin cancer. Taken together, PDIA3 has a strong impact on gene expression and physiology, including genomic response to 1,25-dihydroxyvitamin D.