Induction of anchorage independent growth by heparin-binding EGF-like growth factor (HB-EGF)

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is init ially synthesized as a membrane bound protein that is subsequently processe d to yield an similar to 74 amino acid secreted product. To investigate the biological activities of HB-EGF and its role(s) in tumor formation, the fu ll-length HB-EGF cDNA was cloned under the regulation of the mouse metallot hionein promoter and stably expressed in HB-EGF deficient mouse L cells. HB -EGF immunoreactive proteins of 21 and 24 kDa were observed from transfecte d MLC lysates, and these lysates exhibited the ability to bind to the EGF r eceptor, stimulate H-3-thymidine uptake in BALB/c-3T3 cells, and induce anc horage independent growth (AIG) of normal rat kidney (NRK) cells. Furthermo re, NRK cells treated with either E, coli-derived or vaccinia virus-derived HB-EGF, as well as NRK cells directly transfected with the HB-EGF construc t, demonstrated Ale. We conclude that HB-EGF is a potent growth factor capa ble of stimulating altered cell growth and anchorage independence.