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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Docosahexaenoic Acid Modulates a HER2-Associated Lipogenic Phenotype, Induces Apoptosis, and Increases Trastuzumab Action in HER2-Overexpressing Breast Carcinoma Cells

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Ravacci, Graziela Rosa [1, 2, 3] ; Brentani, Maria Mitzi [2, 3] ; Tortelli, Tharcisio Citrangulo [4] ; Torrinhas, Raquel Suzana M. M. [1] ; Santos, Jessica Reis [1] ; Logullo, Angela Flavia [5] ; Waitzberg, Dan Linetzky [1]
Total Authors: 7
[1] Univ Sao Paulo, Sch Med, Dept Gastroenterol, LIM 35, BR-01246903 Sao Paulo, SP - Brazil
[2] Univ Sao Paulo, Sch Med, Dept Radiol & Oncol, BR-01246903 Sao Paulo, SP - Brazil
[3] Univ Sao Paulo, Support Grp Res Food & Nutr NAPAN, BR-01246903 Sao Paulo, SP - Brazil
[4] Canc Inst State Sao Paulo ICESP, Sao Paulo, SP - Brazil
[5] Sao Paulo Fed Univ UNIFESP EPM, Pathol Dept, Sao Paulo, SP - Brazil
Total Affiliations: 5
Document type: Journal article
Web of Science Citations: 6

In breast cancer, lipid metabolic alterations have been recognized as potential oncogenic stimuli that may promote malignancy. To investigate whether the oncogenic nature of lipogenesis closely depends on the overexpression of HER2 protooncogene, the normal breast cell line, HB4a, was transfected with HER2 cDNA to obtain HER2-overexpressing HB4aC5.2 cells. Both cell lines were treated with trastuzumab and docosahexaenoic acid. HER2 overexpression was accompanied by an increase in the expression of lipogenic genes involved in uptake (CD36), transport (FABP4), and storage (DGAT) of exogenous fatty acids (FA), as well as increased activation of ``de novo{''} FA synthesis (FASN). We further investigate whether this lipogenesis reprogramming might be regulated by mTOR/PPAR gamma pathway. Inhibition of the mTORC1 pathway markers, p70S6 K1, SREBP1, and LIPIN1, as well as an increase in DEPTOR expression (the main inhibitor of the mTOR) was detected in HB4aC5.2. Based on these results, a PPAR gamma selective antagonist, GW9662, was used to treat both cells lines, and the lipogenic genes remained overexpressed in the HB4aC5.2 but not HB4a cells. DHA treatment inhibited all lipogenic genes (except for FABP4) in both cell lines yet only induced death in the HB4aC5.2 cells, mainly when associated with trastuzumab. Neither trastuzumab nor GW9662 alone was able to induce cell death. In conclusion, oncogenic transformation of breast cells by HER2 overexpression may require a reprogramming of lipogenic genetic that is independent of mTORC1 pathway and PPAR gamma activity. This reprogramming was inhibited by DHA. (AU)