INHIBITION OF CRIPTO EXPRESSION AND TUMORIGENICITY IN HUMAN COLON-CANCER CELLS BY ANTISENSE RNA AND OLIGODEOXYNUCLEOTIDES

CRIPTO is an epidermal growth factor-related gene expressed in a major ity of human colorectal tumors. To assess the role of CRIPTO in the gr owth control of human colon cancer, we have treated human colon carcin oma GEO and CBS cells, that possess high levels of CRIPTO, and WIDR co lon cancer cells, that are negative for CRIPTO expression, with two an tisense phosphorothioate oligodeoxynucleotides complementary to the 5' end of the human CRIPTO mRNA. Both antisense oligodeoxynucleotides si gnificantly reduced endogenous CRIPTO protein levels and inhibited GEO and CBS cell growth in monolayer and in semisolid medium, whereas the y did not affect WIDR cell growth. In addition, GEO, CBS and WIDR cell s were infected with a recombinant retroviral vector containing the hy gromycin-resistance gene and a 900 bp EcoRI-EcoRI coding fragment of t he human CRIPTO cDNA oriented in the 3' to 5' direction. GEO and CBS C RIPTO antisense infectants exhibited a 60 to 70% reduction in CRIPTO p rotein expression, in monolayer growth and in soft agar cloning effici ency as compared to parental noninfected cells. In contrast, infection of WIDR cells with the CRIPTO antisense retrovirus did not alter thei r growth. Finally, GEO CRIPTO antisense infectants formed tumors in nu de mice that were significantly smaller and had a larger latency perio d as compared to noninfected GEO cells.