Amphiregulin anti‐sense oligodeoxynucleotides inhibit growth and transformation of a human colon carcinoma cell line

Abstract

Amphiregulin (AR) is a secreted heparin‐binding growth factor that is structurally and functionally related to epidermal growth factor (EGF) and transforming growth factor a (TGFα). GEO cells are from a human colon cancer cell line that expresses high levels of AR protein and mRNA. To assess the role of AR in colon‐cancer cell proliferation and transformation, 2 different anti‐sense 20‐mer phosphorothioate oligodeoxy‐nucleotides (AR AS‐1 and AR AS‐2 S‐oligos) complementary to the 5′ sequence of AR mRNA were synthesized. Both AR AS S‐oligos were able to inhibit the anchorage‐dependent growth (ADG) of GEO cells. The 2 AR AS S‐oligos were equipotent when used in equimolar concentrations. In particular, a 40% growth inhibition was observed at a concentration of 10 μM, while a mis‐sense S‐oligo used as control had no effect on GEO cell growth. The AR AS‐1 S‐oligo used at the same concentration also inhibited by 40% the ³H‐thymidine incorporation by DNA of GEO cells. The anchorage‐independent growth (AIG) of GEO cells was even more significantly affected by AR AS S‐oligo treatment. In fact, up to 80% inhibition of the AIG of GEO cells was observed when cells were treated with 10 μM of both AR AS S‐oligos. Finally, the AR AS S‐oligos were able to specifically inhibit AR protein expression in GEO cells, as assessed by immunocytochemistry. These data suggest that AR is involved in colon‐cancer cell transformation, and that AR may represent a suitable target for gene therapy in human colon carcinomas.