SYNERGISTIC ANTIPROLIFERATIVE ACTIVITY OF SURAMIN AND INTERFERON-ALPHA-2A AGAINST HUMAN COLORECTAL ADENOCARCINOMA CELL-LINES - IN-VITRO STUDIES

Suramin, a polysulphonated naphthylurea proven to be an effective anti cancer agent against selected tumours, and alpha 2A-interferon (alpha 2A-IFN) were investigated for their combined effects on HCT-8, HCT-15, CL-D, SW-480 and SW-620 human colorectal adenocarcinoma cell lines. A ll lines were sensitive to clinically achievable concentrations of sur amin in a dose-dependent manner, while alpha 2A-IFN alone induced only a modest reduction of cell growth. Concomitant treatment with suramin and alpha 2A-IFN resulted in a synergistic inhibition of cell viabili ty in each cell line at all doses tested. However, when suramin and al pha 2A-IFN were administered sequentially, inhibition of cell viabilit y was clearly dependent on the timing of treatment schedule, with maxi mum effect obtained when alpha 2A-IFN was administered prior to surami n. In contrast, pretreatment with suramin was markedly inferior to the former one. In conclusion, suramin and alpha 2A-IFN exert a synergist ic effect on human colorectal cell proliferation in vitro at clinicall y achievable concentrations. This observation may have clinical releva nce although the mechanisms of interaction remain to be elucidated.