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Updated: Jun 16, 2026
Studying TGF-β Signaling and TGF-β-induced Epithelial-to-mesenchymal Transition in Breast Cancer and Normal Cells
Published on: October 27, 2020
Gbetagamma signaling promotes breast cancer cell migration and invasion
Joseph K Kirui1, Yan Xie, Dennis W Wolff
1Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska 68178, USA.
Abstract:
Signaling through G protein-coupled receptors (GPCRs) promotes breast cancer metastasis. G proteins convey GPCR signals by dissociating into Galpha and Gbetagamma subunits. The aim of the present study was to determine whether blockade of Gbetagamma signaling suppresses breast cancer cell migration and invasion, which are critical components of metastasis. Conditioned media (CM) of NIH-3T3 fibroblasts are widely used as chemoattractants in in vitro cancer metastasis studies. Expression of a Gbetagamma scavenger peptide attenuated NIH-3T3 CM-induced migration and invasion of both metastatic breast cancer MDA-MB-231 and MDA-MB-436 cells by 40 to 50% without effects on cell viability. Migration and invasion of cells in response to NIH-3T3 CM were also blocked by 8-(4,5,6-trihydroxy-3-oxo-3H-xanthen-9-yl)-1-naph-thalene-carboxylic acid) (M119K), a Gbetagamma inhibitor, with maximum inhibition exceeding 80% and half-maximal inhibitory concentration (IC50) values of 1 to 2 microM. M119K also attenuated Rac-dependent formation of lamellipodia, a key structure required for metastasis. Constitutively active Rac1 rescued Gbetagamma blockade-mediated inhibition of breast cancer cell migration, whereas dominant negative Rac1 inhibited cell migration similar to Gbetagamma blockade. Furthermore, M119K suppressed Gi protein-coupled CXC chemokine receptor 4 (CXCR4)-dependent MDA-MB-231 cell migration by 80% with an IC50 value of 1 microM, whereas tyrosine kinase receptor-dependent cell migration was significantly less inhibited. However, CXCR4-dependent inhibition of adenylyl cyclase, a Gialpha-mediated response in MDA-MB-231 cells, was not blocked by M119K but was blocked by pertussis toxin, which selectively inactivates Gialpha. This report is the first to directly demonstrate the role of Gbetagamma in cancer cell migration and invasion and suggests that targeting Gbetagamma signaling pathways may provide a novel strategy for suppressing breast cancer metastasis.
Insights
Blocking G protein beta-gamma (Gβγ) signaling significantly suppresses breast cancer cell migration and invasion. This study demonstrates Gβγ
Area of Science:
- Oncology
- Cell Biology
- Biochemistry
Background:
- G protein-coupled receptors (GPCRs) play a crucial role in promoting breast cancer metastasis.
- G proteins, upon GPCR signaling, dissociate into Galpha and Gbetagamma (Gβγ) subunits, mediating downstream effects.
- Breast cancer cell migration and invasion are critical steps in the metastatic cascade.
Purpose of the Study:
- To investigate whether blocking Gbetagamma (Gβγ) signaling can suppress breast cancer cell migration and invasion.
- To elucidate the role of Gβγ in mediating chemoattractant-induced breast cancer cell motility.
Main Methods:
- Utilized NIH-3T3 fibroblast conditioned media (CM) as a chemoattractant for breast cancer cell lines (MDA-MB-231, MDA-MB-436).
- Employed a Gbetagamma scavenger peptide and a specific Gbetagamma inhibitor (M119K) to block Gβγ signaling.
- Assessed cell migration, invasion, lamellipodia formation, and Rac1 activity.
- Investigated the specific role of Gβγ in CXC chemokine receptor 4 (CXCR4)-dependent migration versus tyrosine kinase receptor-dependent migration.
Main Results:
- Gbetagamma (Gβγ) scavenger peptide attenuated NIH-3T3 CM-induced migration and invasion by 40-50% without affecting cell viability.
- The Gβγ inhibitor M119K blocked cell migration and invasion by over 80% (IC50: 1-2 μM) and inhibited Rac-dependent lamellipodia formation.
- M119K specifically suppressed CXCR4-dependent migration (IC50: 1 μM) while having less effect on tyrosine kinase receptor-dependent migration.
- Gαi-mediated adenylyl cyclase inhibition via CXCR4 was not affected by M119K, confirming pathway specificity.
Conclusions:
- This study provides the first direct evidence for the critical role of Gbetagamma (Gβγ) signaling in driving breast cancer cell migration and invasion.
- Targeting Gbetagamma (Gβγ) signaling pathways represents a promising novel therapeutic strategy for inhibiting breast cancer metastasis.
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