Doxorubicin-induced inhibition of prolidase activity in human skin fibroblasts and its implication to impaired collagen biosynthesis.

One of the recognized side effects accompanying doxorubicin administration is poor wound healing resulting from impairement of collagen biosynthesis. However, the precise mechanism of doxorubicin-induced inhibition of collagen synthesis has not been established. We considered prolidase, an enzyme involved in collagen metabolism as a possible target for doxorubicin-induced inhibition of synthesis of this protein. Prolidase [E.C.3.4.13.9] cleaves imidodipeptides containing C-terminal proline, providing large amount of proline for collagen resynthesis. Therefore, we compared the effect of doxorubicin on prolidase activity and collagen biosynthesis in cultured human skin fibroblasts. We have found that doxorubicin induces coordinately inhibition of prolidase activity (IC50 approximately 10 +/- 3 microM) and collagen biosynthesis (IC50 approximately 15 +/- 3 microM) in cultured human skin fibroblasts. The inhibitory effect of doxorubicin on prolidase activity and collagen biosynthesis was not due to cytotoxicity of this drug as shown by cell viability tetrazoline test. The decrease in prolidase activity in fibroblasts treated with doxorubicin was not accompanied by differences in the amount of the enzyme protein recovered from these cells as shown by western immunoblot analysis. It may suggest that the inhibition is a posttranslational event. The data presented here rise possibility that doxorubicin-induced decrease in collagen biosynthesis is mostly due to the inhibition of prolidase activity.