RAPID COMMUNICATION p53 Functional Impairment and High p21waf1'cip1 Expression in Human T-cell LymphotropidLeukemia Virus Type

Human T-cell lymphotropic/leukemia virus type I (HTLV-I) is associated with T-cell transformation both in vivo and in vitro. Although some of the mechanisms responsible for transformation remain unknown, increasing evidence s u p ports a direct role of viral as well as dysregulated cellular proteins in transformation. We investigated the potential role of the tumor suppressor gene p53 and of the p53-regulated gene, p21Waf''C'P' (wild-type p53 activated fragment l/ cycling dependent kinases [cdks] interacting protein I), in HTLV-l-infected T cells. We have found that the majority of HTLV-l-infected T cells have the wild-type p53 gene. However, its function in HTLV-l-transformed cells appears to be impaired, IS shown by the lack of appropriate p53-mediated responses to ionizing radiation ( W . Interestingly, the expres-