Silencing MED1 Sensitizes Breast Cancer Cells to Pure Anti-Estrogen Fulvestrant In Vitro and In Vivo

Lijiang Zhang, Jiajun Cui, Marissa Leonard, Kenneth Nephew, Yongquan Li, Xiaoting Zhang

Research output: Contribution to journalArticle

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Abstract

Pure anti-estrogen fulvestrant has been shown to be a promising ER antagonist for locally advanced and metastatic breast cancer. Unfortunately, a significant proportion of patients developed resistance to this type of endocrine therapy but the molecular mechanisms governing cellular responsiveness to this agent remain poorly understood. Here, we've reported that knockdown of estrogen receptor coactivator MED1 sensitized fulvestrant resistance breast cancer cells to fulvestrant treatment. We found that MED1 knockdown further promoted cell cycle arrest induced by fulvestrant. Using an orthotopic xenograft mouse model, we found that knockdown of MED1 significantly reduced tumor growth in mice. Importantly, knockdown of MED1 further potentiated tumor growth inhibition by fulvestrant. Mechanistic studies indicated that combination of fulvestrant treatment and MED1 knockdown is able to cooperatively inhibit the expression of ER target genes. Chromatin immunoprecipitation experiments further supported a role for MED1 in regulating the recruitment of RNA polymerase II and transcriptional corepressor HDAC1 on endogenous ER target gene promoter in the presence of fulvestrant. These results demonstrate a role for MED1 in mediating resistance to the pure anti-estrogen fulvestrant both in vitro and in vivo.

Original languageEnglish
Article numbere70641
JournalPLoS One
Volume8
Issue number7
DOIs
StatePublished - Jul 30 2013

Fingerprint

breast neoplasms
estrogens
Estrogens
Cells
Breast Neoplasms
neoplasms
DNA-directed RNA polymerase
growth retardation
chromatin
antagonists
genes
animal models
promoter regions
therapeutics
mice
Tumors
Genes
Co-Repressor Proteins
neoplasm cells
In Vitro Techniques

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Silencing MED1 Sensitizes Breast Cancer Cells to Pure Anti-Estrogen Fulvestrant In Vitro and In Vivo. / Zhang, Lijiang; Cui, Jiajun; Leonard, Marissa; Nephew, Kenneth; Li, Yongquan; Zhang, Xiaoting.

In: PLoS One, Vol. 8, No. 7, e70641, 30.07.2013.

Research output: Contribution to journalArticle

Zhang, Lijiang ; Cui, Jiajun ; Leonard, Marissa ; Nephew, Kenneth ; Li, Yongquan ; Zhang, Xiaoting. / Silencing MED1 Sensitizes Breast Cancer Cells to Pure Anti-Estrogen Fulvestrant In Vitro and In Vivo. In: PLoS One. 2013 ; Vol. 8, No. 7.
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