Inhibitors of anchorage‐independent growth affect the growth of transformed cells on poly(2‐hydroxyethyl methacrylate)‐coated surfaces

Abstract

We have described a microplate colorimetric assay to quantitate anchorage-independent cell growth, using plates coated with an anti-adhesive polymer poly (2-hydroxyethyl methacrylate) (polyHEMA).We investigated whether this method could be applied to human cancer cells of epithelial origin. HAG-1, a non-tumorigenic human gall-bladder carcinoma cell line, and its pSVneo and c-H-ras transfectants, which are also non-tumorigenic, did not grow on a polyHEMA-surface. In contrast, the v-src transformant which produced tumors in nude mice and formed colonies in soft agar, was able to proliferate on the coated surface, suggesting that tumorigenicity of human cancer cells correlates with the ability to grow on a polyHEMA-coated surface. We report on the feasibility of this method as a screening system for inhibitors of oncogenic transformation. Herbimycin A and radicicol, which have been reported to block Src function, suppressed the growth of v-src-transformed NRK and HAG-1 cells on the non-adhesive polyHEMA-surface at concentrations significantly lower than on plastic. Differences in the inhibitory concentrations were not observed with KB cells, and cytotoxic agents such as adriamycin did not show any selectivity between the 2 surfaces. Growth of ras-transformed cells on the coated surface was selectively blocked by L-739,749, a farnesyltransferase inhibitor. The results demonstrate that compounds causing reversion of transformed cells to normal, hence, selectively inhibiting cell growth in anchorage-independent conditions, can be screened using this microtiter plate assay.