Estrogen promotes stemness and invasiveness of ER-positive breast cancer cells through Gli1 activation.

Abstract

BACKGROUND:

Although long-term estrogen (E2) exposure is associated with increased breast cancer (BC) risk, and E2 appears to sustain growth of BC cells that express functional estrogen receptors (ERs), its role in promoting BC stem cells (CSCs) remains unclear. Considering that Gli1, part of the Sonic hedgehog (Shh) developmental pathway, has been shown to mediate CSCs, we investigated whether E2 and Gli1 could promote CSCs and epithelial-mesenchymal transition (EMT) in ER+ BC cell lines.

METHODS:

We knocked down Gli1 in several BC cells using a doxycycline-controlled vector, and compared Gli1-knockdown cells and Gli1+ cells in behavior and expression of ER, Gli1, ALDH1 (BC-CSC marker), Shh, Ptch1 (Shh receptor) and SOX2, Nanog and Bmi-1 (CSC-associated transcriptions factors), using PCR; tissue microarrays, western blot; chromatin immunoprecipitation q-PCR, confocal immunofluorescence microscopy; fluorescence-activated cell sorting; annexin-flow cytometry (for apoptosis); mammosphere culture; and colony formation, immunohistochemistry, Matrigel and wound-scratch assays.

RESULTS:

Both mRNA and protein expressions of ER correlated with those of Gli1 and ALDH1. E2 induced Gli1 expression only in ER+ BC cells. E2 promoted CSC renewal, invasiveness and EMT in ER+/Gli1+ cells but not in Gli1-knockdown cells.

CONCLUSIONS:

Our results indicate that estrogen acts via Gli1 to promote CSC development and EMT in ER+ BC cells. These findings also imply that Gli1 mediates cancer stem cells, and thus could be a target of a novel treatment for ER+ breast cancer.

• Authors: Ying Sun, Yunshan Wang, Cong Fan, Peng Gao, Xiuwen Wang, Guangwei Wei, Junmin Wei
• Journal: Molecular cancer (Mol Cancer) Vol. 13 Pg. 137 (Jun 03 2014) ISSN: 1476-4598 [Electronic] England
• PMID: 24889938 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• BMI1 protein, human
• Estrogens
• GLI1 protein, human
• Hedgehog Proteins
• Homeodomain Proteins
• Isoenzymes
• NANOG protein, human
• Nanog Homeobox Protein
• PTCH1 protein, human
• Patched Receptors
• Patched-1 Receptor
• RNA, Small Interfering
• Receptors, Cell Surface
• Receptors, Estrogen
• SHH protein, human
• SOX2 protein, human
• SOXB1 Transcription Factors
• Transcription Factors
• Zinc Finger Protein GLI1
• Aldehyde Dehydrogenase 1 Family
• ALDH1A1 protein, human
• Retinal Dehydrogenase
• Polycomb Repressive Complex 1

Topics

• Aldehyde Dehydrogenase 1 Family
• Breast Neoplasms (genetics, metabolism, pathology)
• Cell Line, Tumor
• Epithelial-Mesenchymal Transition (drug effects)
• Estrogens (metabolism, pharmacology)
• Female
• Gene Expression Regulation, Neoplastic
• Hedgehog Proteins (genetics, metabolism)
• Homeodomain Proteins (genetics, metabolism)
• Humans
• Isoenzymes (genetics, metabolism)
• Nanog Homeobox Protein
• Neoplasm Invasiveness
• Neoplastic Stem Cells (drug effects, metabolism, pathology)
• Patched Receptors
• Patched-1 Receptor
• Polycomb Repressive Complex 1 (genetics, metabolism)
• RNA, Small Interfering (genetics, metabolism)
• Receptors, Cell Surface (genetics, metabolism)
• Receptors, Estrogen (genetics, metabolism)
• Retinal Dehydrogenase (genetics, metabolism)
• SOXB1 Transcription Factors (genetics, metabolism)
• Signal Transduction
• Transcription Factors (antagonists & inhibitors, genetics, metabolism)
• Zinc Finger Protein GLI1