Considerable evidences have shown that autophagy has an important role in tumor chemoresistance. However, it is still unknown whether the lncRNA HULC (highly upregulated in liver cancer) is involved in autophagy and chemoresistance of hepatocellular carcinoma (HCC). In this study, we for the first time demonstrated that treatment with antitumor reagents such as oxaliplatin, 5-fluorouracil and pirarubicin (THP) dramatically induced HULC expression and protective autophagy. Silencing of HULC sensitized HCC cells to the three antitumor reagents via inhibiting protective autophagy. Ectopic expression of HULC elicited the autophagy of HCC cells through stabilizing silent information regulator 1 (Sirt1) protein. The investigation for the corresponding mechanism by which HULC stabilized Sirt1 revealed that HULC upregulated ubiquitin-specific peptidase 22 (USP22), leading to the decrease of ubiquitin-mediated degradation of Sirt1 protein by removing the conjugated polyubiquitin chains from Sirt1. Moreover, we found that miR-6825-5p, miR-6845-5p and miR-6886-3p could decrease the level of USP22 protein by binding to the 3'-untranlated region of USP22 mRNA. All the three microRNAs (miRNAs) were downregulated by HULC, which resulted in the elevation of USP22. In addition, we showed that the level of HULC was positively correlated with that of Sirt1 protein in human HCC tissues. Collectively, our data reveals that the pathway 'HULC/USP22/Sirt1/ protective autophagy' attenuates the sensitivity of HCC cells to chemotherapeutic agents, suggesting that this pathway may be a novel target for developing sensitizing strategy to HCC chemotherapy.

Sepsis is characterized by systematic inflammation and contributes to cardiac dysfunction. This study was designed to examine the effect of Akt activation on LPS-induced cardiac anomalies and underlying mechanism(s) involved. Mechanical and intracellular Ca2+ properties were examined in myocardium from wild-type and transgenic mice with cardiac-specific chronic Akt overexpression following LPS (4 mg/kg, i.p.) challenge. Akt signaling cascade (Akt, PTEN, GSK3β), stress signal (ERK, JNK, p38), apoptotic markers (BAX, caspase-3/-9), ER stress markers (GRP78, GADD153, eIF2α), inflammatory markers (TNFα, IL-1β, IL-6) and autophagic markers (Beclin-1, LC3B, Atg7 and p62) were evaluated. Our results revealed that LPS induced marked decrease in ejection fraction, fractional shortening, cardiomyocyte contractile capacity with dampened intracellular Ca2+ release and clearance, elevated ROS generation and decreased GSH/GSSG ratio, increased ERK, JNK, p38, GRP78, GADD153, eIF2α, BAX, caspase-3 and - 9, downregulated Bcl-2, the effects of which were significantly attenuated or obliterated by Akt activation. Akt activation itself did not affect cardiac contractile and intracellular Ca2+ properties, ROS production, oxidative stress, apoptosis and ER stress. In addition, LPS upregulated levels of Beclin-1, LC3B and Atg7, while suppressing p62 accumulation. Akt activation did not affect Beclin-1, LC3B, Atg7 and p62 in the presence or absence of LPS. Akt overexpression promoted phosphorylation of Akt and GSK3β. In vitro study using the GSK3β inhibitor SB216763 mimicked the response elicited by chronic Akt activation. Taken together, these data showed that Akt activation ameliorated LPS-induced cardiac contractile and intracellular Ca2+ anomalies through inhibition of apoptosis and ER stress, possibly involving an Akt/GSK3β-dependent mechanism.

Aim: Aliskiren (ALK) is a renin inhibitor that has been used in the treatment of hypertension. The aim of this study was to determine whether ALK could ameliorate pressure overload-induced heart hypertrophy and fibrosis, and to elucidate the mechanisms of action. Methods: Transverse aortic constriction (TAC) was performed in mice to induce heart pressure overload. ALK (150 mg·kg -1 ·d -1, po), the autophagy inhibitor 3-methyladenine (10 mg·kg -1 per week, ip) or the PKCβI inhibitor LY333531 (1 mg·kg, po) was administered to the mice for 4 weeks. Heart hypertrophy, fibrosis and function were evaluated based on echocardiography, histological and biochemical measurements. Mechanically stretched-cardiomyocytes of rats were used for in vitro experiments. The levels of signaling proteins were measured using Western blotting, while the expression of the relevant genes was analyzed using real-time QRT-PCR. Results: TAC induced marked heart hypertrophy and fibrosis, accompanied by high levels of Ang II in plasma and heart, and by PKCβI/α and ERK1/2 phosphorylation in heart. Meanwhile, TAC induced autophagic responses in heart, i.e. increases in autophagic structures, expression of Atg5 and Atg16 L1 mRNAs and LC3-II and Beclin-1 proteins. These pathological alterations in TAC-mice were significantly ameliorated or blocked by ALK administration. In TAC-mice, 3-methyladenine administration also ameliorated heart hypertrophy, fibrosis and dysfunction, while LY333531 administration inhibited ERK phosphorylation and autophagy in heart. In mechanically stretched-cardiomyocytes, CGP53353 (a PKCβI inhibitor) prevented ERK phosphorylation and autophagic responses, while U0126 (an ERK inhibitor) blocked autophagic responses. Conclusion: ALK ameliorates heart hypertrophy, fibrosis and dysfunction in the mouse model in setting of chronic pressure overload, via suppressing Ang II-PKCβI-ERK1/2-regulated autophagy.