1A). A progressive up-regulation of total and activated AKT and mTOR, and of p70S6K, RHEB, RPS6, HIF-1α, inactivated/phosphorylated 4E-BP1, and activated/phosphorylated SGK1 occurred in preneoplastic and neoplastic rat lesions, when compared with control liver (Fig. 1A; Supporting Fig. 1).

Phosphorylated/activated AKT, mTOR, and inactivated/phosphorylated 4E-BP1 levels were further confirmed by immunohistochemistry (IHC) (Fig. 1B). Also, levels of AMP-activated kinase (AMPK) alpha proteins were assessed, because AMPKs are known to negatively modulate de novo lipogenesis induced by mTOR27 (Fig. 1A; Supporting Fig. 1). AMPKα1 levels were equivalent in healthy livers, preneoplastic foci and HCCs, whereas those of AMPKα2 and activated/phosphorylated selleck products AMPKα levels were down-regulated in preneoplastic foci and HCCs (Fig. 1A; Supporting Fig. 1). In accord, the levels of markers of AMPK activation, including phosphorylated/inactivated 3-hydroxy-3-methylglutaryl-coenzyme A (CoA) reductase (HMGCR), phosphorylated/inactivated acetyl-CoA Osimertinib research buy carboxylase

(ACAC), and phosphorylated/inactivated regulatory-associated protein of mTOR (Raptor), were lowest in preneoplastic foci and HCCs, when compared with healthy livers (Fig. 1A; Supporting Fig. 1). Because we recently demonstrated that activation of the AKT/mTOR pathway induces aberrant lipogenesis,26 we assessed by immunoblotting whether the same occurred in the rat model. Levels of proteins involved in fatty acid biosynthesis, including fatty acid synthase (FASN), ACAC, and stearoyl-CoA desaturase 1 (SCD1), were progressively increased in

preneoplastic liver foci and HCC, when compared with unaltered liver tissues (Fig. 2A; Supporting Fig. 2). In contrast, ATP citrate lyase (ACLY) selleck screening library overexpression peaked in foci, but was still higher in HCC, when compared with control liver. Aldo-keto reductase family 1, member B10 (AKR1B10), which binds and prevents ACAC degradation by the proteasome, thus increasing fatty acid synthesis,28 was instead up-regulated only in HCC. Similarly, AKR1B10-ACAC complexes (sign of AKR1B10 prolipogenic activity) were equivalent in control liver and preneoplastic foci, but significantly increased in HCC. Upstream inducers of lipogenesis, including carbohydrate-responsive element-binding protein (chREBP), protein kinase C lambda/iota (PRKCλ/ι), and peroxisome proliferator-activated receptor gamma (PPARγ), were progressively increased from preneoplastic foci to HCC. Furthermore, ubiquitin-specific protease 2a (USP2a), which sustains FASN activity by impeding its ubiquitin-dependent degradation in the liver,26 was induced in preneoplastic and neoplastic lesions.