Expression of transforming growth factor-beta receptor 11 mRNA in cyclosporine-induced gingival overgrowth

Abstract

Gingival overgrowth (GO), characterized by increased cellular and extracellular matrix components in gingival tissue, is a frequent side effect of cyclosporine (CsA). In previous studies, elevated levels of transforming growth factor-beta (TGF-beta) have been detected in GO tissue, which led to the conclusion that TGF-beta plays a major part in the pathogenesis. TGF-beta activity is mediated by three receptors; TGF-beta receptor II (TGF-beta RII), the most important, has been immunohistochemically detected in GO and normal gingival tissue. The aim of this study was to clarify whether TGF-beta RII is overexpressed in CsA-induced GO. The expression of TGF-beta RII mRNA in GO tissue of patients on CsA (n = 10, 5 women, aged 42.5 +/- 14.9 years) with renal transplantation (transplant duration 3.6 +/- 0.96 years) was compared with that in healthy gingiva of control subjects (n = 10, 5 women, aged 42.5 +/- 7.6 years). Serniquantitative reverse transcribed-polymerase chain reactions (RT-PCR) were applied with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal standard. TGF-beta RII mRNA was readily detected in the GO tissue of patients on CsA. The level of TGF-P RII mRNA relative to GAPDH in GO cases was not significantly higher than the relative TGF-beta mRNA level in normal gingiva (0.60 +/- 0.16 vs 0.52 +/- 0.19; P = .575). The precise mechanism of CsA-induced GO remains uncertain. According to our results, TGF-beta RII was not upregulated in CsA-induced GO, and may have no important role in this disorder. However, the involvement of TGF-beta in the molecular pathology of GO may be mediated via TGF-beta RI or RIII.