Nevertheless, it is important to notice LBH589 that the aforementioned metabolic alterations presumably depend on, at least partly, different molecular mechanisms in preneoplastic and neoplastic rat liver lesions. Indeed, these metabolic changes can be easily explained for the preneoplastic foci, which are confined to the anatomic borders of the liver acinus and drain hyperinsulinemic blood from islet grafts. In HCC, however, the often scattered islet graft remnants can only be partly responsible for these metabolic alterations, although they can be regularly demonstrated

within tumors.21 Although the intralesional insulin concentration cannot be measured, it can be assumed that the former hyperinsulinemia, induced by the islet grafts, is significantly diminished within HCC. Thus, the metabolic alterations detected in the tumors cannot exclusively be explained as a consequence of increased insulin signaling. Previous

findings indicate that the IR is overexpressed in rat HCC, but not in preneoplastic foci.23 The latter finding might suggest that elevated levels of IR might provide a higher sensitivity for insulin signaling in HCC, despite the absence of elevated insulin levels. In the present study, we Pirfenidone cost show that suppression of the AKT inhibitors, TRB3, PHLPP1, and PHLPP2, and up-regulation of AKT and its upstream inducers, PIK3CA and PIK3CB, occur exclusively in rat HCC. These alterations, together with the peculiar up-regulation of the ACAC stabilizer, AKR1B10, in HCC, indicate the selleckchem existence in rat liver tumors of a complex genetic program leading to the perpetuation of the molecular mechanism that is solely dependent on insulin signaling in the preneoplastic foci. Additional molecular mechanisms might contribute to metabolic alterations in rat HCC and are currently under investigation. At the molecular level, in accord with

recent studies,29, 37, 38 we show that AKT signaling exerts its effects on metabolism through mTORC1-dependent and -independent mechanisms (Fig. 7). Under insulin growth-promoting stimuli, selective inhibition of mTORC1 by rapamycin triggered a significant decrease in glycolysis, a less pronounced reduction of lipogenesis, and no effect on both gluconeogenesis and some lipogenesis-related proteins (e.g., AKR1B10, USP2a, PRKCλ/ι, chREBP, AMPKα2, and INSIG2) in HCC cell lines. On the other hand, use of either the AKT1/2 inhibitor or concomitant suppression of PI3K and mTOR promoted a much stronger growth restraint, a more pronounced fall in lipid biosynthesis, and reactivation of gluconeogenesis in HCC cells supplemented with insulin. Besides their pathogenetic significance, the present results support the use of PI3K/mTOR and mTORC1/2 dual inhibitors, rather than mTORC1 single inhibitors, in the treatment of HCC with activated AKT.