Levels of FASN expression in different human carcinomas attracted considerable interest of this enzyme as a target for therapy [10, 11]. In this study, we show that adenocarcinoma of lung cancer, is among the foremost of cancers that could potentially be treated by inhibiting FASN.
C75 has been studied in A549 lung cancer xenografts  where it induces a transient and reversible growth inhibition. EGCG anti-cancer effects in lung cancer have also been evidenced and, besides FASN-inhibition, several mechanisms of action have been proposed, such as G3BP1 (GTPase activating protein (SH3 domain) binding protein) inhibition , generation of Reactive Oxygen Species (ROS)  or induction of p53-dependent transcription .
To further investigate the implications of FASN inhibition in lung adenocarcinoma, we have analyzed the blockage of FASN by EGCG and C75 in A549 lung cancer cells. Firstly, we ensured similar levels of FASN inhibition by C75- and EGCG-treatment (96,9% and 89,3% of control, respectively). As C75 had no effect on the abundance of FASN protein levels and EGCG diminished the levels of this enzyme, it is probable that in the EGCG-treated cells, the reduction of FASN activity could be in part consequence of the reduced FASN protein levels.
The inhibition of FASN activity by EGCG and C75 was accompanied by an induction of apoptosis, and changes in cell growth and proliferation signaling pathways. The active phosphorylated form of EGFR (p-EGFR) was completely abolished after 6 hours of exposure to EGCG. Consequently, phosphorylated forms of ERK1/2 (p-ERK1/2), AKT (p-AKT) and mTOR (p-mTOR) were also markedly decreased. It is remarkable that comparable concentrations of C75, even with prolonged exposure (48 hours), only partially decreased total levels of EGFR and phosphorylated levels of AKT (p-AKT). Several data supported a relationship between HER2 and FASN in breast cancer, head and neck carcinomas, HER2-overexpressed fibroblasts and other carcinomas [11, 32–35]. Furthermore, some authors have demonstrated the blocking effects of the FASN inhibitor EGCG on all members of epidermal growth factor receptor (ErbB) family [11, 36–38].
This is the first evidence that EGFR is involved in the regulation of FASN expression in a lung cancer model with EGFR-overexpression. EGFR may be another EGCG-direct target that through inhibition of its downstream signalers (Akt, ERK1/2 and mTOR) is able to down-regulate FASN expression at two different levels: 1, at the transcriptional level through the sterol response element-binding proteins 1c (SREBP-1c), the FASN-transcription factor mediated by PI3K/Akt and MAPK/ERK1/2 pathways ; 2, at the translational level, through Akt-mTOR-signaling and its downstream effectors, eIF4G and S6K (reviewed in ref ) as seen in breast cancer  and in human hepatoma cells .
In addition, we corroborate a FASN-ErbB loop, described in breast cancer. The FASN disruption impedes synthesis of lipids, which are integrated in membrane lipid raft in which cell surface receptors, ErbB among others, accommodate and sense to tumourigenic pathways . C75 is a direct and competitive inhibitor of FASN . Consequently, we have seen a strong and fast inhibition of FASN activity with C75 treatment and a later effect on levels of EGFR and phosphorylation of it downstream effector Akt (p-Akt), what brings us to corroborate the idea of a FASN-lipid rafts-ErbB inhibition loop.
An important result of our study is the in vivo drug-efficacy study and long-term body weight evaluation. EGCG and C75 markedly blocked the growth of A549 lung cancer xenografts while the tumour volumes of control animals growth significantly until the final day study. C75-treated mice showed a marked decrease in body weight after each administration (close to 6% of initial body weight). This result accords to the data that C75 is able to stimulate CPT system and fatty acid β-oxidation, which has been related to the severe decrease of food intake and induction of weight loss in rodents . In contrast, we have not observed a significant decrease in body weight in the animals treated for 33 days with EGCG.
A key feature of EGCG is that does not affect CPT activity (as it is shown in vitro in Figure 1) and, consequently, it does not induce weight loss in experimental animals. This result in a lung cancer model are in agreement with our previous findings in a mouse breast cancer model  and reinforces the hypothesis that CPT-activation is the cause of weight loss in xenografts models. Our data also reveal for the first time that the effects of EGCG in lung carcinoma involve different pathways than C75 but also that the undesirable side effects observed in C75 treated-mice are not produced in EGCG-treated mice.