Decreased Expression of Beta-defensins Alters Keratinocyte Proliferation and Differentiation

Objective: The antimicrobial peptides of human beta-defensins (hBDs) expressed by keratinocytes are important components of the innate immune responses. hBD-1 is a tumor suppresser gene whose re-expression inhibits cancer cell proliferation (Sun CQ. et al. Cancer Res 2006). We hypothesized that decreased expression of hBDs induced cell growth. The present study examined whether decreased expression of hBDs altered keratinocyte proliferation and differentiation. Methods: We established decreased transcription of hBD-1, -2 and -3 in HaCaT cells, a keratinocyte cell line (sihBD1-HaCaT, sihBD2-HaCaT and sihBD3-HaCaT). The cells were grown in DMEM supplemented with 10% fetal bovine. Cell growth rate was evaluated by XTT assays (Sigma-Aldrich, MO). Expression levels of involucrin, keratin 10 and 14 were observed by quantitative RT-PCR using TagMan probes (Applied Biosystems, CA). keratin 14, keratin 10 and involucrin were used as markers of the basal layer, early and late differentiation, respectively. The results were compared between sihBDs-HaCaT and pSilencer^TM 4.1-CMV hygro Negative Control (Ambion, TX) transfected HaCaT cells (control cells). The statistical significance of the difference was analyzed using one-way ANOVA. Results: The cell growth rate of sihBD1 and sihBD3-HaCaT cells at 24, 48, 72 and 96 hours was significantly higher than those of control cells (p<0.01). The rates of proliferation of sihBD2-HaCaT cells at 72 and 96 hours were significantly higher than those of control cells (p<0.01). We found that the expression level of keratin 10 was significantly lower in sihBD1 and 3-HaCaT cells compared to control cells(p<0.01), whereas that of keratin 14 was higher in sihBD1 and 3-HaCaT than control (p<0.05). The expression level of involucrin was significantly lower in sihBD-2 than in the control (p<0.05). Conclusion: The present study provides that decreased expression of hBD-1, -2 and -3 may induce their cell growth accompanied by an alteration in the expression of differentiation markers.