Epigenetic Modifications Alter Expression of Antimicrobial Peptides in Oral Carcinoma

Objective:Epithelial antimicrobial peptides play an important role in protective barrier of oral epithelium against bacterial infection. Alteration of expression of antimicrobial peptides including beta-defensin (hBD) s, cathelicidin/LL-37 (LL-37) and psoriasin (PS) is often observed in carcinoma cells. Epigenetic modifications are often involved in the transcriptional level of mRNAs. The present study investigated how epigenetic modifications are involved in expression of the antimicrobial peptide. Methods: Six oral SCC-established cell lines (SCC-9, SAS, HSC-3, OSC-19, BSC-OF), normal oral keratinocytes (NOK) were used. The expression level of hBD-1, -2, -3, LL-37, psoriasin, Dorsomysin-like defensin (DLD) was estimated by quantitative RT-PCR using TaqMan probes (Applied Biosystem, CA). In order to examine whether DNA hypermethylation and/or histone deacetylation are involved in the transcriptional levels, cells were treated with DNA methyltransferase inhibitor, 5-aza-dCyd (Sigma, MO) for 72hr or histone deacetylase inhibitor, Trihcostatin A (TSA: Sigma) for 48hr. No treatments were used as controls. The relative expression of each mRNA was calculated as the ΔΔCt. Student's-t test was used to determine if the average expression level in experiment and control were different. Results: The expression levels of hBD-1, -2, -3, LL-37 and PS varied among the cell lines. Expression levels of hBD-1, -2, -3, LL37 and PS in OSC-19 and BSC-OF treated with 100μM of 5-aza-dCyd were significantly higher than each control (p<0.001). OSC-19 and BSC-OF showed more than 10-fold induction of hBD-1,-3 and LL37 expression. Expression levels of hBD-2, -3 and PS in OSC-19 and BSC-OF treated with 600nM of TSA were significantly higher than each control (p<0.001). Conclusions: The results indicate that epigenetic modification may alter transcriptional level of antimicrobial peptides in some oral carcinomas.