Abstract
Background Integrin avß6 promotes migration, invasion, and survival of cancer cells; however, the relevance and role of avß6 has yet to be elucidated in breast cancer.
Methods Protein expression of integrin subunit beta6 (ß6) was measured in breast cancers by immunohistochemistry (n > 2000) and ITGB6 mRNA expression measured in the Molecular Taxonomy of Breast Cancer International Consortium dataset. Overall survival was assessed using Kaplan Meier curves, and bioinformatics statistical analyses were performed (Cox proportional hazards model, Wald test, and Chi-square test of association). Using antibody (264RAD) blockade and siRNA knockdown of ß6 in breast cell lines, the role of avß6 in Human Epidermal Growth Factor Receptor 2 (HER2) biology (expression, proliferation, invasion, growth in vivo) was assessed by flow cytometry, MTT, Transwell invasion, proximity ligation assay, and xenografts (n = 3), respectively. A student’s t-test was used for two variables; three-plus variables used one-way analysis of variance with Bonferroni’s Multiple Comparison Test. Xenograft growth was analyzed using linear mixed model analysis, followed by Wald testing and survival, analyzed using the Log-Rank test. All statistical tests were two sided.
Results High expression of either the mRNA or protein for the integrin subunit ß6 was associated with very poor survival (HR = 1.60, 95% CI = 1.19 to 2.15, P = .002) and increased metastases to distant sites. Co-expression of ß6 and HER2 was associated with worse prognosis (HR = 1.97, 95% CI = 1.16 to 3.35, P = .01). Monotherapy with 264RAD or trastuzumab slowed growth of MCF-7/HER2-18 and BT-474 xenografts similarly (P < .001), but combining 264RAD with trastuzumab effectively stopped tumor growth, even in trastuzumab-resistant MCF-7/HER2-18 xenografts.
Conclusions Targeting avß6 with 264RAD alone or in combination with trastuzumab may provide a novel therapy for treating high-risk and trastuzumab-resistant breast cancer patients.
Methods Protein expression of integrin subunit beta6 (ß6) was measured in breast cancers by immunohistochemistry (n > 2000) and ITGB6 mRNA expression measured in the Molecular Taxonomy of Breast Cancer International Consortium dataset. Overall survival was assessed using Kaplan Meier curves, and bioinformatics statistical analyses were performed (Cox proportional hazards model, Wald test, and Chi-square test of association). Using antibody (264RAD) blockade and siRNA knockdown of ß6 in breast cell lines, the role of avß6 in Human Epidermal Growth Factor Receptor 2 (HER2) biology (expression, proliferation, invasion, growth in vivo) was assessed by flow cytometry, MTT, Transwell invasion, proximity ligation assay, and xenografts (n = 3), respectively. A student’s t-test was used for two variables; three-plus variables used one-way analysis of variance with Bonferroni’s Multiple Comparison Test. Xenograft growth was analyzed using linear mixed model analysis, followed by Wald testing and survival, analyzed using the Log-Rank test. All statistical tests were two sided.
Results High expression of either the mRNA or protein for the integrin subunit ß6 was associated with very poor survival (HR = 1.60, 95% CI = 1.19 to 2.15, P = .002) and increased metastases to distant sites. Co-expression of ß6 and HER2 was associated with worse prognosis (HR = 1.97, 95% CI = 1.16 to 3.35, P = .01). Monotherapy with 264RAD or trastuzumab slowed growth of MCF-7/HER2-18 and BT-474 xenografts similarly (P < .001), but combining 264RAD with trastuzumab effectively stopped tumor growth, even in trastuzumab-resistant MCF-7/HER2-18 xenografts.
Conclusions Targeting avß6 with 264RAD alone or in combination with trastuzumab may provide a novel therapy for treating high-risk and trastuzumab-resistant breast cancer patients.
| Original language | English |
|---|---|
| Article number | dju169 |
| Number of pages | 14 |
| Journal | Journal of the National Cancer Institute (JNCI) |
| Volume | 106 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - Aug 2014 |
Keywords
- Animals
- Antibodies, Monoclonal, Humanized
- Antigens, Neoplasm
- Antineoplastic Agents
- Antineoplastic Combined Chemotherapy Protocols
- Breast Neoplasms
- Female
- Flow Cytometry
- Gene Expression Regulation, Neoplastic
- Gene Knockdown Techniques
- Humans
- Immunohistochemistry
- Integrins
- Kaplan-Meier Estimate
- Mice
- Mice, SCID
- Molecular Targeted Therapy
- Receptor, erbB-2
- Treatment Outcome
- Xenograft Model Antitumor Assays
Access to Document
- Publisher final version
© The Author 2014. Published by Oxford University Press. jnci.oxfordjournals.org This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected]