Epidermal growth factor stimulates the anchorage-independent growth of human squamous cell carcinomas overexpressing its receptors

We examined the effects of epidermal growth factor (EGF) on the anchorage-dependent and -independent growth of four human squamous carcinoma cell lines that overexpress EGF receptors. While EGF inhibited anchorage-dependent growth, it stimulated anchorage-independent growth of all four cell lines tested. The results suggest that the proliferative responses to EGF are characterized by a preference for anchorage-independent, rather than -dependent growth, in cells overexpressing EGF receptors. Moreover, as EGF has been shown to stimulate the in vivo growth of squamous carcinoma cells overexpressing EGF receptors, it is also suggested that the in vitro EGF responsiveness of these cells in soft agar, but not in monolayer, better correlates with the in vivo EGF responsiveness.