Cell Culture Parental, nontransformed HB4a cells and HER2-overexpressing HB4a variant cells, HB4aC5.2, were cultured in RPMI-1640 with 10% fetal bovine serum (FBS) (GIBCO, Invitrogen, Brazil) plus ampicillin, hydrocortisone, and insulin (Sigma-Aldrich, Brazil) at 37C in a 10% CO2 humidified incubator [25, 26]. 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 impartial of mTORC1 pathway and PPARactivity. This reprogramming was inhibited by DHA. 1. Introduction Cell lipogenic metabolism has traditionally been considered a minor anabolic energy-storage pathway, yet its role in various cancers is usually progressively being acknowledged [1C5]. Endogenous fatty acid (FA) biogenesis may constitute an oncogenic stimulus that drives normal epithelial cells towards malignancy [1C5]. Moreover, emerging evidence indicates that Drostanolone Propionate this oncogenic nature of human lipogenesis depends on the activity and/or expression of important protooncogenes, such as human epidermal growth factor receptor 2 (HER2are detected in approximately 20C30% of breast carcinomas and are associated with a poor prognosis [6C10]. Hyperactivation of HER2 promotes aberrant cell proliferation and tumorigenesis, thereby making HER2 an important therapeutic target against breast malignancy [6C10]. Currently, the primary treatment for HER2-overexpressing tumors is usually trastuzumab (Herceptin) [11C14]. Trastuzumab is usually a monoclonal antibody that is designed to target the extracellular domain name of HER2 and block its function. However, response rates for trastuzumab monotherapy have been reported to range from 12% to 34% with a median period of 9 months [9, 10]. Thus, it appears that the mechanism of action of HER2 is not yet fully comprehended. We previously showed that HER2 hyperactivation and signaling in breast cancer cells depend strongly on the location of the receptor within membrane lipid Drostanolone Propionate rafts . In breast cancer cells, HER2 overexpression may be accompanied by an increase in cell membrane lipid raft microdomains, thereby establishing a vicious cycle of aberrant cell signaling [1, 15]. Recent experimental evidence revealed that this dimerization of HER2 (as a homo- or heterodimer with users Drostanolone Propionate of its own family) is associated with lipid rafts [1, 16]. In addition, HER2-mediated proliferation and survival signals depend around the colocalization of HER2 with other membrane proteins (e.g., integrins and extranuclear factor of the estrogen receptor [ER]) in lipid rafts Drostanolone Propionate [17, 18]. Accordingly, it is possible that an increase in the number of lipid rafts in HER2-overexpressing cells can enhance the activation of these oncogenic receptors . To ensure lipid raft synthesis, HER2 promotes the activation of fatty acid synthase (FASN). Its final product, palmitate, is frequently used to synthesize membrane microdomains [1, 15, 19]. In a previous study, when this pathway was inhibited by omega-3 docosahexaenoic fatty acid (DHA), lipid rafts were disrupted and cell apoptosis was induced . Thus, HER2 overexpression in breast cancer cells is usually associated with constitutive upregulation of the endogenous FASN-catalyzed biogenesis of palmitate. The upregulation of palmitate biogenesis represents a lipogenic benefit for the proliferation and survival of breast cancer cells by providing lipid raft components for the proper localization and activation GLUR3 of HER2 in the cell membrane [1, 2, 15, 19]. However, accumulation of palmitate in nonadipose tissue promptly stimulates lipolysis and apoptosis and can act as an inhibitory opinions transmission for endogenous FA synthesis [1, 2, 20C22]. On the other hand, these events seem to be avoided in HER2-overexpressing breast carcinoma cells, through the conversion and storage of FAs as triglycerides by peroxisome proliferator-activated receptor gamma (PPARincrease the expression of genes related to uptake and transport of exogenous FA, contributing to the establishment of lipogenic phenotype in HER2-overexpressing cells [1, 2]. Therefore, in these cells, upregulation of FASN appears to be a downstream manifestation of an early and common deregulation of upstream regulatory circuits that impact the lipogenic genetic program . It is believed that this regulation of lipogenesis occurs through mTOR protein [1, 2]. The HER2/mTOR pathway results in SREBP1 activation which can increase the transcription of PPARendogenous ligands and regulates the expression ofFASN[1, 2]. However, the details of this process Drostanolone Propionate remain unclear, since activation of components of the mTOR pathway, as mTORC1,.