Expression of Transforming Growth Factor-β Receptor II mRNA in Cyclosporine-Induced Gingival Overgrowth

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-β (TGF-β) have been detected in GO tissue, which led to the conclusion that TGF-β plays a major part in the pathogenesis. TGF-β activity is mediated by three receptors; TGF-β receptor II (TGF-β RII), the most important, has been immunohistochemically detected in GO and normal gingival tissue. The aim of this study was to clarify whether TGF-β RII is overexpressed in CsA-induced GO. The expression of TGF-β 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). Semiquantitative reverse transcribed-polymerase chain reactions (RT-PCR) were applied with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal standard. TGF-β RII mRNA was readily detected in the GO tissue of patients on CsA. The level of TGF-β RII mRNA relative to GAPDH in GO cases was not significantly higher than the relative TGF-β 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-β RII was not upregulated in CsA-induced GO, and may have no important role in this disorder. However, the involvement of TGF-β in the molecular pathology of GO may be mediated via TGF-β RI or RIII.