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Updated: Mar 12, 2026
Intra-Cardiac Injection of Human Prostate Cancer Cells to Create a Bone Metastasis Xenograft Mouse Model
Published on: November 4, 2022
Pharmacological targeting of CXCL12/CXCR4 signaling in prostate cancer bone metastasis
M Katie Conley-LaComb1, Louie Semaan1, Rajareddy Singareddy1
1Department of Urology, Wayne State University, School of Medicine, 9245 Scott Hall, 540 E. Canfield Avenue, Detroit, MI, 48201, USA.
Background:
The CXCL12/CXCR4 axis transactivates HER2 and promotes intraosseous tumor growth. To further explore the transactivation of HER2 by CXCL12, we investigated the role of small GTP protein Gαi2 in Src and HER2 phosphorylation in lipid raft membrane microdomains and the significance of CXCR4 in prostate cancer bone tumor growth.
Methods:
We used a variety of methods such as lipid raft isolation, invasion assays, an in vivo model of intratibial tumor growth, bone histomorphometry, and immunohistochemistry to determine the role of CXCR4 signaling in lipid raft membrane microdomains and effects of targeting of CXCR4 for bone tumor growth.
Results:
We determined that (a) CXCL12/CXCR4 transactivation of EGFR and HER2 is confined to lipid raft membrane microdomains, (b) CXCL12 activation of HER2 and Src is mediated by small GTP proteins in lipid rafts, (c) inhibition of the CXCL12/CXCR4 axis through plerixafor abrogates the initial establishment of tumor growth without affecting the growth of established bone tumors, and (d) inhibition of EGFR signaling through gefitinib leads to inhibition of established bone tumor growth.
Conclusions:
These data suggest that lipid raft membrane microdomains are key sites for CXCL12/CXCR4 transactivation of HER2 via small GTP binding protein Gαi2 and Src kinase. The initial establishment of prostate cancer is supported by the endosteal niche, and blocking the CXCL12/CXCR4 axis of this niche along with its downstream signaling severely compromises initial establishment of tumors in the bone microenvironment, whereas expanding bone tumors are sensitive only to the members of growth factor receptor inhibition.
Insights
The CXCL12/CXCR4 axis promotes prostate cancer bone tumor growth via HER2 transactivation in lipid rafts. Targeting this axis blocks initial tumor establishment, while established tumors respond to EGFR inhibition.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- The CXCL12/CXCR4 axis is implicated in HER2 transactivation and prostate cancer bone tumor growth.
- Investigated the role of small GTP protein Gαi2 in Src and HER2 phosphorylation within lipid raft microdomains.
- Examined the significance of CXCR4 in prostate cancer bone tumor progression.
Purpose of the Study:
- To explore HER2 transactivation by CXCL12.
- To elucidate the role of Gαi2 in Src and HER2 phosphorylation in lipid rafts.
- To determine the importance of CXCR4 in prostate cancer bone metastasis.
Main Methods:
- Lipid raft isolation and invasion assays.
- In vivo models of intratibial tumor growth and bone histomorphometry.
- Immunohistochemistry to analyze CXCR4 signaling and therapeutic targeting.
Main Results:
- CXCL12/CXCR4-mediated transactivation of EGFR and HER2 occurs within lipid raft microdomains.
- Small GTP proteins in lipid rafts mediate CXCL12 activation of HER2 and Src.
- Plerixafor inhibition of CXCL12/CXCR4 abrogated initial tumor establishment but not established tumors.
- Gefitinib inhibition of EGFR signaling reduced established bone tumor growth.
Conclusions:
- Lipid raft microdomains are critical for CXCL12/CXCR4-mediated HER2 transactivation via Gαi2 and Src kinase.
- Blocking the CXCL12/CXCR4 axis in the endosteal niche compromises initial prostate cancer establishment in bone.
- Established bone tumors are sensitive to growth factor receptor inhibition, not CXCL12/CXCR4 axis inhibition.
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