hBD-2 is downregulated in oral carcinoma cells by DNA hypermethylation, and increased expression of hBD-2 by DNA demethylation and gene transfection inhibits cell proliferation and invasion

Abstract

Human β-defensin-2 (hBD-2) is a type of epithelial antimicrobial peptide. The expression level of hBD-2 mRNA is lower in oral carcinoma cells (OCCs) than in healthy oral epithelium. Yet, it is still unknown how hBD-2 expression is downregulated in OCCs. The present study investigated DNA hypermethylation of hBD-2 in OCCs and the effect of the demethylation and increased expression of hBD-2 on cell proliferation and invasion. Six different types of oral carcinoma cell lines (OSC-19, BSC-OF, SAS, HSC-2, HSC-4 and HSY) and normal oral keratinocytes (NOKs) were used. The expression levels of hBD-2 in all OCCs were significantly lower than that in the NOKs. Treatment with DNA methyltransferase inhibitor, 5-aza-dC, at the concentration of 50 μM significantly induced upregulation of expression of hBD-2 in the OCCs. Using methylation-specific PCR, DNA hypermethylation was observed in all OCCs. These results suggest that DNA hypermethylation is, at least in part, involved in the decreased expression of hBD-2 in OCCs. We examined the effect of 5-aza-dC on the cell proliferation and invasive ability of OCCs. The cell invasion assays showed that the number of OCCs treated with 5-aza-dC on the filters was significantly lower than that of the controls. We examined whether increased expression of hBD-2 generated by gene transfection inhibited the proliferation and invasion of SAS cells. The number of SAS cells exhibiting increased expression of hBD-2 on the filters in the invasion assay were significantly lower on day 7 when compared with the control. hBD-2 may function as a tumor suppressor. Increased expression of hBD-2 induced by demethylation or increased expression generated by gene transfection may be useful therapeutic methods for oral carcinoma.

Human Beta Defensins and Cancer: Contradictions and Common Ground

“…Mechanisms for dysregulation of hBD-2 and−3 are also cancer type dependent. For hBD-2, the nuclear factor kappa b (NF-κB) pathway was found to regulate it in esophageal cancer (30), while in OSCC it is regulated by DNA hypermethylation (28). For hBD-3 the EGFR pathway activates it in OSCC (33), while in HPV-associated oropharyngeal cancer it is regulated via the tumor suppressor p53 (43).…”

“…Increased expression of hBD-2 generated by gene transfection inhibits the proliferation and invasion of the OSCC cell line (SAS), possibly via G1/S arrest and pRB gene expression, indicating that hBD-2 may act as a tumor suppressor (28). Interestingly, as described above, hBD-2 has been reported to be under-expressed in OSCC (Table 1; Figure 1A).…”

Alterations in gene expression and DNA methylation profiles in gastric cancer cells obtained from ascitic fluids collected before and after chemotherapy

“…STYK1 is a receptor protein tyrosine kinase that serves important roles in a diverse array of cellular and developmental processes, including cell proliferation, differentiation, and survival (11). However, the 19 genes that were expressed at lower levels included DEFB4A, which has previously been reported to be a potential tumor suppressor gene (12).…”

Enediyne-activated, EGFR-targeted human β-defensin 1 has therapeutic efficacy against non-small cell lung carcinoma

“…Interestingly, defensins are more prone to interact with tumor cells than normal cells, resulting in disruption of their membranes. This preference is likely due to the cationic properties of these proteins, which enable them to interact with the high percentage of anionic molecules, including phosphatidylserine and sialic acid residues, present in the cancer cell membrane [22,25,26]. Recently, defensin NaD1 was shown to induce tumor cell lysis by directly binding to PI(4,5)P2 in the plasma membrane [27].…”