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HER2 (erbB-2)-targeted effects of the omega-3 polyunsaturated fatty acid, alpha-linolenic acid (ALA; 18:3n-3), in breast cancer cells: the "fat features" of the "Mediterranean diet" as an "anti-HER2 cocktail".
Clin Transl Oncol 2006; 8(11):812-20CT

Abstract

BACKGROUND

Data derived from epidemiological and experimental studies suggest that alphalinolenic acid (ALA; 18:3n-3), the main omega-3 polyunsaturated fatty acid (PUFA) present in the Western diet, may have protective effects in breast cancer risk and metastatic progression. A recent pilot clinical trial assessing the effects of ALA-rich dietary flaxseed on tumor biological markers in postmenopausal patients with primary breast cancer demonstrated significant reductions in tumor growth and in HER2 (erbB-2) oncogene expression.

HYPOTHESIS

The molecular mechanism by which ALA inhibits breast cancer cell growth and metastasis formation may involve a direct regulation of HER2, a well-characterized oncogene playing a key role in the etiology, progression and response to some chemo- and endocrine therapies in approximately 20% of breast carcinomas.

METHODS

Using HER2-specific ELISA, flow cytometry, immunofluorescence microscopy, Western blotting, RT-PCR and HER2 promoter-reporter analyses, we characterized the effects of exogenous supplementation with ALA on the expression of HER2 oncogene, a master key player in the onset and metastasis formation of breast cancer disease. Metabolic status (MTT) assays were performed to evaluate the nature of the cytotoxic interaction between ALA and the humanized anti-HER2 monoclonal antibody trastuzumab (Herceptin). To study these issues we used BT-474 and SKBr-3 breast cancer cells, which naturally exhibit amplification of the HER2 oncogene.

RESULTS

ALA treatment dramatically suppressed the expression of HER2-coded p185Her-2/neu oncoprotein as determined by ELISA, flow cytometry, immunofluorescence microscopy and immunoblotting techniques. Interestingly, ALA-induced down-regulation of p185Her-2/neu correlated with a transcriptional response as no HER2 mRNA signal could be detected by RT-PCR upon treatment with optimal concentrations of ALA (up to 20 microM). Consistent with these findings, ALA exposure was found to dramatically repress the activity of a Luciferase reporter gene driven by the HER2 promoter. Moreover, the nature of the cytotoxic interaction between ALA and trastuzumab (Herceptin) revealed a significant synergism as assessed by MTT-based cell viability assays.

CONCLUSIONS

i) These findings reveal that the omega-3 PUFA ALA suppresses overexpression of HER2 oncogene at the transcriptional level, which, in turn, interacts synergistically with anti-HER2 trastuzumab- based immunotherapy. ii) Our results molecularly support a recent randomized double-blind placebo-controlled clinical trial suggesting that ALA may be a potential dietary alternative or adjunct to currently used drugs in the management of HER2-positive breast carcinomas. iii) Considering our previous findings demonstrating the <<HER2 upregulatory actions>> of the omega-6 PUFA linolenic acid (LA; 18:2n-6) and the <<HER2 down-regulatory actions >> of the omega-3 PUFA docosahexaenoic acid (DHA; 22:6n-3) and of the omega-9 monounsaturated fatty acid oleic acid (OA; 18:1n-9), it is reasonable to suggest that a low omega-6/omega-3 PUFA ratio and elevated MUFA levels, the two prominent <<fat features>> of the <<Mediterranean diet>>, should be extremely efficient at blocking HER2 expression in breast cancer cells.

Authors+Show Affiliations

Fundació d'Investigació Biomédica de Girona Dr. Josep Trueta (IdIBGi), Girona, Catalonia. Spain. javiermenendez72@yahoo.comNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17134970

Citation

Menéndez, Javier A., et al. "HER2 (erbB-2)-targeted Effects of the Omega-3 Polyunsaturated Fatty Acid, Alpha-linolenic Acid (ALA; 18:3n-3), in Breast Cancer Cells: the "fat Features" of the "Mediterranean Diet" as an "anti-HER2 Cocktail"." Clinical & Translational Oncology : Official Publication of the Federation of Spanish Oncology Societies and of the National Cancer Institute of Mexico, vol. 8, no. 11, 2006, pp. 812-20.
Menéndez JA, Vázquez-Martín A, Ropero S, et al. HER2 (erbB-2)-targeted effects of the omega-3 polyunsaturated fatty acid, alpha-linolenic acid (ALA; 18:3n-3), in breast cancer cells: the "fat features" of the "Mediterranean diet" as an "anti-HER2 cocktail". Clin Transl Oncol. 2006;8(11):812-20.
Menéndez, J. A., Vázquez-Martín, A., Ropero, S., Colomer, R., & Lupu, R. (2006). HER2 (erbB-2)-targeted effects of the omega-3 polyunsaturated fatty acid, alpha-linolenic acid (ALA; 18:3n-3), in breast cancer cells: the "fat features" of the "Mediterranean diet" as an "anti-HER2 cocktail". Clinical & Translational Oncology : Official Publication of the Federation of Spanish Oncology Societies and of the National Cancer Institute of Mexico, 8(11), pp. 812-20.
Menéndez JA, et al. HER2 (erbB-2)-targeted Effects of the Omega-3 Polyunsaturated Fatty Acid, Alpha-linolenic Acid (ALA; 18:3n-3), in Breast Cancer Cells: the "fat Features" of the "Mediterranean Diet" as an "anti-HER2 Cocktail". Clin Transl Oncol. 2006;8(11):812-20. PubMed PMID: 17134970.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - HER2 (erbB-2)-targeted effects of the omega-3 polyunsaturated fatty acid, alpha-linolenic acid (ALA; 18:3n-3), in breast cancer cells: the "fat features" of the "Mediterranean diet" as an "anti-HER2 cocktail". AU - Menéndez,Javier A, AU - Vázquez-Martín,Alejandro, AU - Ropero,Santiago, AU - Colomer,Ramón, AU - Lupu,Ruth, PY - 2006/12/1/pubmed PY - 2007/4/25/medline PY - 2006/12/1/entrez SP - 812 EP - 20 JF - Clinical & translational oncology : official publication of the Federation of Spanish Oncology Societies and of the National Cancer Institute of Mexico JO - Clin Transl Oncol VL - 8 IS - 11 N2 - BACKGROUND: Data derived from epidemiological and experimental studies suggest that alphalinolenic acid (ALA; 18:3n-3), the main omega-3 polyunsaturated fatty acid (PUFA) present in the Western diet, may have protective effects in breast cancer risk and metastatic progression. A recent pilot clinical trial assessing the effects of ALA-rich dietary flaxseed on tumor biological markers in postmenopausal patients with primary breast cancer demonstrated significant reductions in tumor growth and in HER2 (erbB-2) oncogene expression. HYPOTHESIS: The molecular mechanism by which ALA inhibits breast cancer cell growth and metastasis formation may involve a direct regulation of HER2, a well-characterized oncogene playing a key role in the etiology, progression and response to some chemo- and endocrine therapies in approximately 20% of breast carcinomas. METHODS: Using HER2-specific ELISA, flow cytometry, immunofluorescence microscopy, Western blotting, RT-PCR and HER2 promoter-reporter analyses, we characterized the effects of exogenous supplementation with ALA on the expression of HER2 oncogene, a master key player in the onset and metastasis formation of breast cancer disease. Metabolic status (MTT) assays were performed to evaluate the nature of the cytotoxic interaction between ALA and the humanized anti-HER2 monoclonal antibody trastuzumab (Herceptin). To study these issues we used BT-474 and SKBr-3 breast cancer cells, which naturally exhibit amplification of the HER2 oncogene. RESULTS: ALA treatment dramatically suppressed the expression of HER2-coded p185Her-2/neu oncoprotein as determined by ELISA, flow cytometry, immunofluorescence microscopy and immunoblotting techniques. Interestingly, ALA-induced down-regulation of p185Her-2/neu correlated with a transcriptional response as no HER2 mRNA signal could be detected by RT-PCR upon treatment with optimal concentrations of ALA (up to 20 microM). Consistent with these findings, ALA exposure was found to dramatically repress the activity of a Luciferase reporter gene driven by the HER2 promoter. Moreover, the nature of the cytotoxic interaction between ALA and trastuzumab (Herceptin) revealed a significant synergism as assessed by MTT-based cell viability assays. CONCLUSIONS: i) These findings reveal that the omega-3 PUFA ALA suppresses overexpression of HER2 oncogene at the transcriptional level, which, in turn, interacts synergistically with anti-HER2 trastuzumab- based immunotherapy. ii) Our results molecularly support a recent randomized double-blind placebo-controlled clinical trial suggesting that ALA may be a potential dietary alternative or adjunct to currently used drugs in the management of HER2-positive breast carcinomas. iii) Considering our previous findings demonstrating the <<HER2 upregulatory actions>> of the omega-6 PUFA linolenic acid (LA; 18:2n-6) and the <<HER2 down-regulatory actions >> of the omega-3 PUFA docosahexaenoic acid (DHA; 22:6n-3) and of the omega-9 monounsaturated fatty acid oleic acid (OA; 18:1n-9), it is reasonable to suggest that a low omega-6/omega-3 PUFA ratio and elevated MUFA levels, the two prominent <<fat features>> of the <<Mediterranean diet>>, should be extremely efficient at blocking HER2 expression in breast cancer cells. SN - 1699-048X UR - https://www.unboundmedicine.com/medline/citation/17134970/HER2__erbB_2__targeted_effects_of_the_omega_3_polyunsaturated_fatty_acid_alpha_linolenic_acid__ALA L2 - http://www.diseaseinfosearch.org/result/960 DB - PRIME DP - Unbound Medicine ER -