Captopril reverses high-glucose-induced growth effects on LLC-PK1 cells partly by decreasing transforming growth factor-beta receptor protein expressions.

Transforming growth factor beta (TGF-beta) may be important in the pathogenesis of diabetic nephropathy, and captopril is effective in treating this disorder. However, the mechanisms of this therapeutic effect as related to TGF-beta and its receptors are not known. Thus, the effects of captopril on cellular growth, TGF-beta 1, and TGF-beta receptors were studied in LLC-PK1 cells cultured in normal (11 mM) or high glucose (27.5 mM). This study found that glucose dose-dependently inhibited cellular mitogenesis while inducing hypertrophy in these cells at 72 h of culture, concomitantly with enhanced TGF-beta 1 messenger RNA (mRNA) and TGF-beta receptor Types I and II protein expressions. Captopril dose-dependently (0.1 to 10 mM) increased cellular mitogenesis and inhibited hypertrophy in these cells. Moreover, captopril also decreased TGF-beta receptor Types I and II protein expressions dose-dependently. However, TGF-beta 1 mRNA was not affected by captopril. It was concluded that high glucose decreased cellular mitogenesis while increasing hypertrophy concomitantly with increased TGF-beta 1 mRNA and TGF-beta receptors in LLC-PK1 cells. Captopril can reverse high-glucose-induced growth effects by decreasing TGF-beta receptor protein expressions.