Selection and characterization of a breast cancer cell line resistant to the antiestrogen LY 117018

D. A. Bronzert, Marc E Lippman, M. E. Lippman

Research output: Contribution to journalArticle

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Abstract

We have selected and cloned a stable variant of the MCF-7 human breast cancer cell line (LY 2) that is resistant to LY 117018 (LY), a potent antiestrogen that inhibits cell growth at concentrations as low as 10-10 M. The cell line was selected by increasing the concentration of LY in the growth medium in a stepwise manner from 10-8 to 10-6 M as the cells became resistant. LY2 has been cloned in soft agar and carried for over 50 passages with no change in resistance. Other antiestrogens, such as tamoxifen and 40-hydroxytamoxifen no longer inhibit cell proliferation of LY 2. The cell line is still responsive to estrogen in a cell proliferation assay, but contains somewhat less estrogen receptors than MCF-7. The cytosolic estrogen receptor sediments to a 4S position on high salt sucrose density gradient centrifugation and is completely shifted to a denser gradient region when the receptor is incubated with a monoclonal antiestrophilin. The nuclear estrogen receptor when covalently labeled with [3H]tamoxifen aziridine has the same mol wt (62,000) in both MCF-7 and LY2 cells, when determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In a competitive binding assay, LY 117018 competes for [3H]estradiol binding to its cytosol receptor with the same K(i) in both MCF-7 and LY2 cells. When the induction of estrogen-specific proteins was examined, no detectable progesterone receptor could be detected in either estrogen-induced or control LY2 cells, in contrast to MCF-7 cells. However, both 52,000- and 160,000-dalton proteins were estrogen inducible in the medium of LY2 and MCF-7 cells, as measured by labeling with [35S]methionine. The phenotypic stability of the antiestrogen resistance in LY2 cells coupled with the cross-resistance to antiestrogens of widely different structures make this cell line an ideal model system for the study of hormone resistance in human breast cancer. In addition, while the mechanism of resistance is currently not elucidated, the selective loss of estrogen-inducible functions in this cell line may provide powerful clues for future study.

Original languageEnglish
Pages (from-to)1409-1417
Number of pages9
JournalEndocrinology
Volume117
Issue number4
StatePublished - Jan 1 1985
Externally publishedYes

Fingerprint

LY 117018
Estrogen Receptor Modulators
MCF-7 Cells
Estrogens
Breast Neoplasms
Cell Line
Estrogen Receptors
Cell Proliferation
Competitive Binding
Density Gradient Centrifugation
Progesterone Receptors
Tamoxifen
Growth
Sodium Dodecyl Sulfate
Methionine
Cytosol
Agar
Sucrose
Polyacrylamide Gel Electrophoresis
Estradiol

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Bronzert, D. A., Lippman, M. E., & Lippman, M. E. (1985). Selection and characterization of a breast cancer cell line resistant to the antiestrogen LY 117018. Endocrinology, 117(4), 1409-1417.

Selection and characterization of a breast cancer cell line resistant to the antiestrogen LY 117018. / Bronzert, D. A.; Lippman, Marc E; Lippman, M. E.

In: Endocrinology, Vol. 117, No. 4, 01.01.1985, p. 1409-1417.

Research output: Contribution to journalArticle

Bronzert, DA, Lippman, ME & Lippman, ME 1985, 'Selection and characterization of a breast cancer cell line resistant to the antiestrogen LY 117018', Endocrinology, vol. 117, no. 4, pp. 1409-1417.
Bronzert, D. A. ; Lippman, Marc E ; Lippman, M. E. / Selection and characterization of a breast cancer cell line resistant to the antiestrogen LY 117018. In: Endocrinology. 1985 ; Vol. 117, No. 4. pp. 1409-1417.
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abstract = "We have selected and cloned a stable variant of the MCF-7 human breast cancer cell line (LY 2) that is resistant to LY 117018 (LY), a potent antiestrogen that inhibits cell growth at concentrations as low as 10-10 M. The cell line was selected by increasing the concentration of LY in the growth medium in a stepwise manner from 10-8 to 10-6 M as the cells became resistant. LY2 has been cloned in soft agar and carried for over 50 passages with no change in resistance. Other antiestrogens, such as tamoxifen and 40-hydroxytamoxifen no longer inhibit cell proliferation of LY 2. The cell line is still responsive to estrogen in a cell proliferation assay, but contains somewhat less estrogen receptors than MCF-7. The cytosolic estrogen receptor sediments to a 4S position on high salt sucrose density gradient centrifugation and is completely shifted to a denser gradient region when the receptor is incubated with a monoclonal antiestrophilin. The nuclear estrogen receptor when covalently labeled with [3H]tamoxifen aziridine has the same mol wt (62,000) in both MCF-7 and LY2 cells, when determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In a competitive binding assay, LY 117018 competes for [3H]estradiol binding to its cytosol receptor with the same K(i) in both MCF-7 and LY2 cells. When the induction of estrogen-specific proteins was examined, no detectable progesterone receptor could be detected in either estrogen-induced or control LY2 cells, in contrast to MCF-7 cells. However, both 52,000- and 160,000-dalton proteins were estrogen inducible in the medium of LY2 and MCF-7 cells, as measured by labeling with [35S]methionine. The phenotypic stability of the antiestrogen resistance in LY2 cells coupled with the cross-resistance to antiestrogens of widely different structures make this cell line an ideal model system for the study of hormone resistance in human breast cancer. In addition, while the mechanism of resistance is currently not elucidated, the selective loss of estrogen-inducible functions in this cell line may provide powerful clues for future study.",
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