INHIBITION OF HAMSTER MELANOMA GROWTH BY ESTROGEN

  • 15 January 1987
    • journal article
    • research article
    • Vol. 47  (2) , 453-459
Abstract
A malignant hamster melanoma cell line HM-1 derived from the heterogenous malignant hamster melanoma MM1 contains a specific, high affinity binding protein for estrogens. Partial purification of the binding protein with ammonium sulfate (40% saturation) increased mean binding content (3.1 .+-. 1.2 (SD) fmol/mg protein) 15-fold without any change in affinity (1010 M-1). The binding protein sedimented at 8-9S on 10-30% low salt sucrose gradients and 9-10S in the presence of 20 mM myolybdate ion. Addition of 0.4 M KCl shifted the 8S peak to 4S. Binding was specific, saturable, and indicative of a single class of high affinity sites over a concentration range of 0.01-10.0 nM [3H]estradiol. Estradiol produced a dose related inhibition of HM-1 growth in vitro without altering the growth of an additional line (HM-2) which did not bind estrogen. The antiestrogen tamoxifen (10-7 M) also significantly inhibited HM-1 melanoma growth in vitro, which was reversed by the addition of estradiol (10-9 M). HM-I xenografts grew faster in female BALB/c-nu/nu mice than male mice while there was no sex difference in HM-2 growth. Pharmacological doses of estradiol and the antiestrogen nafoxidine significantly inhibited HM-1 growth without altering tumor incidence or latency. Our observations suggest that HM-1 cell lines bind estrogens specifically and with high affinity and that hamster melanoma cells positive for this binding protein respond to estrogen.