PRODUCTION OF TRANSFORMING GROWTH-FACTORS BY HUMAN-COLON CANCER LINES

  • 1 March 1986
    • journal article
    • research article
    • Vol. 46  (3) , 1164-1169
Abstract
Three human colon cancer lines (SW 480, SW 620, WIDR) were characterized as to their production of molecules with transforming growth factor (TGF)-like activity. Production of both TGF.alpha.-like and TGF.beta.-like activity was quantitated, as were cellular receptors for these molecules, and growth response in soft agar to exogenous epidermal growth factor (EGF) (as a substitute for TGF.alpha.) and TGF.beta.. Serum-free medium conditioned by these cells showed differing amounts of TGF.alpha.-like and TGF.beta.-like competing activity in EGF and TGF.beta. radioreceptor assays. Likewise the cells showed differing abilities to bind 125I-labeled EGF and TGF.beta.. SW 620 cells produced relatively large quantities of TGF.alpha.-like activity and had no detectable EGF receptors; specific TGF.beta. binding was observed. SW 480 cells produced the most TGF.beta.-like activity and had no measurable TGF.beta. membrane receptors, but EGF receptors were detectable. WIDR cells had both EGF and TGF.beta. membrane receptors and produced relatively low levels of EGF and TGF.beta. receptor-competing activity. All three of the cell lines grew spontaneously in soft agar (in medium containing 10% serum). In contrast to other carcinoma cell lines, exogenous EGF and TGF.beta. had no significant effect on soft agar growth of the colon carcinoma cells. The production of both TGF.alpha.-like and TGF.beta.-like polypeptides by colon carcinoma cell lines has been shown, yet involvement of these factors in autostimulatory activity could not be demonstrated. The possibility that these endogenous factors could be involved in paracrine stimulation of stromal cells remains to be explored.