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Cholera‐toxin‐enhanced growth of human breast cancer cell lines in vitro and in vivo : Interaction with estrogen
Author(s) -
Sheffield L. G.,
Welsch C. W.
Publication year - 1985
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910360411
Subject(s) - cholera toxin , in vivo , estrogen , medicine , endocrinology , estrogen receptor , in vitro , breast carcinoma , cell growth , biology , cell culture , growth inhibition , toxin , cancer research , breast cancer , cancer , microbiology and biotechnology , biochemistry , genetics
Cholera toxin (which increases intracellular cAMP levels) significantly ( p < 0.05) increased the growth of MCF‐7, T47‐D and Hs578T human breast carcinoma cells in vitro . The effect of cholera toxin on growth of MCF‐7 and T47‐D cells was more pronounced in the presence of 17β‐estradiol ( p <0.05), indicating a synergism between cAMP and estradiol in growth control of estrogen‐receptor‐positive breast carcinoma cells. This interaction was not observed in the estrogenreceptor‐negative cell line Hs578T. Daily injections of cholera toxin into female athymic nude mice bearing MCF‐7 or Hs578T tumors resulted in significantly ( p < 0.05) increased growth of the tumors. Cholera toxin treatments, in addition, significantly ( p < 0.05) increased cAMP levels in tumor cells and tumor tissue, in vitro and in vivo , respectively. The results of this study clearly demonstrated that an increase in cAMP levels via cholera toxin treatment causes enhanced growth ( in vitro and in vivo ) of estrogen‐receptorpositive and ‐negative human breast carcinoma cells and, although estrogen alone was not mitogenic to the estrogen‐receptor‐positive breast carcinoma cells in vitro , the steroid was mitogenic to these cells in the presence of elevated cellular cAMP levels.