Mammary adenocarcinomas induced by medroxyprogesterone acetate: hormone dependence and EGF receptors of BALB/c in vivo sublines.
Mammary adenocarcinomas were induced by medroxy-progesterone acetate (MPA) in female BALB/c mice. From 5 primary tumors, 9 different sublines were established by s.c. transplantation into syngeneic female mice; these developed after a long latent period (4-12 months). Each subline was transplanted both into 4 mice treated with 40mg of MPA depot (s.c. contralaterally to the tumor inoculum) and into 4 non-treated mice. Of the 9 sublines, 6 proved to be hormone-dependent (MPA-D) and 3 hormone-independent or autonomous (MPA-I). However, even the autonomous lines, when treated with MPA, showed a slight increase in growth. All MPA-D lines had a high content of ER (20-254 fmoles/mg of protein), PR (63-710), PRL-R (44-74) and low or non-detectable EGF-R. Of the 3 MPA-I sublines that were studied, 2 showed a high content of ER (16-125), PR (27-708), PRL-R (19-70) and EGF-R (29-65) while the other one had a low content of ER (0-36), PR (0-13), no EGF-R and moderate PRL-R (15-52). Spontaneous mammary tumors of BALB/c and C3H origin, which also showed an MPA-I pattern of tumor growth, had high levels of EGF-R. We postulate that MPA has a direct effect on mammary tumor cells in MPA-D lines and that the expression of EGF-R is correlated with an autonomous pattern of growth.
Lanari
C
C
Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina, Buenos Aires, Argentina.
Kordon
E
E
Molinolo
A
A
Pasqualini
C D
CD
Charreau
E H
EH
D000230:Adenocarcinoma / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003692:Delayed-Action Preparations; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D008525:Medroxyprogesterone / Q000031:analogs & derivatives* / Q000494:pharmacology; D017258:Medroxyprogesterone Acetate; D051379:Mice; D008807:Mice, Inbred BALB C; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism
D003692:Delayed-Action Preparations; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D017258:Medroxyprogesterone Acetate; D066246:ErbB Receptors; D008525:Medroxyprogesterone