Acitretin decreases tumor cell-induced angiogenesis

The effects of acitretin and etretinate on angiogenesis induced in Balb/c mice by intradermal injection of keratinocyte tumor cell lines were evaluated. It was shown that both retinoids are capable of inhibiting angiogenesis evoked by a human epidermoid carcinoma cell line (A431). Acitretin, but not etretinate, inhibited also angiogenesis induced by the spontaneously transformed murine keratinocyte cell line Pam 212 and by the established tumorigenic SKv cell line harboring the HPV16 genome. We suggest that inhibition of blood vessel formation may be one of the mechanisms responsible for the anticancerogenic effect of retinoids.