DIFFERENTIAL RESPONSIVENESS OF PROLIFERATION AND CYTOKERATIN RELEASE TO STRIPPED SERUM AND ESTROGEN IN THE HUMAN BREAST-CANCER CELL-LINE, MCF-7

In vitro research into hormone sensitivity and the relation to prolife ration of cytokeratin release from cancer cells is scarce. Therefore, we examined the stimulation of proliferation and the release of cytoke ratins in a breast cancer cell culture model. Cell growth was stimulat ed by 17 beta-oestradiol (10(-11) M), stripped serum (10%) and by the two together. Cytokeratin release was stimulated only by stripped seru m, oestradiol having no effect. After long incubation periods (>12 h), cytokeratin release also commenced in the control and oestradiol trea tments. Release rate versus time analysis suggested that there are two different release processes. Cytokeratin release was first stimulated at a stripped serum concentration approximately 100 times lower than that which initiated proliferation. Pharmacological alteration of prol iferation with cordyceptin resulted in growth changes without alterati ons in cytokeratin release. We conclude that cytokeratin release in th ese cells is unrelated to proliferation, independent of oestrogen acti on and probably in some way related to growth factor receptor function . Copyright (C) 1996 Elsevier Science Ltd