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Sorafenib resistance remains a major obstacle for the effective treatments of hepatocellular carcinoma (HCC). Recent studies indicate that activated Akt contributes to the acquired resistance to sorafenib, and miR-21 dysregulates phosphatase and tensin homolog (PTEN), which inhibits Akt activation. Sorafenib-resistant HCC cells were shown to be refractory to sorafenib-induced growth inhibition and apoptosis. Akt and its downstream factors were highly activated and/or upregulated in sorafenib-resistant cells. Inhibition of autophagy decreased the sensitivity of sorafenib-resistant cells to sorafenib, while its induction had the opposite effect. Differential screening of miRNAs showed higher levels of miR-21 in sorafenib-resistant HCC cells. Exposure of HCC cells to sorafenib led to an increase in miR-21 expression, a decrease in PTEN expression and sequential Akt activation. Transfection of miR-21 mimics in HCC cells restored sorafenib resistance by inhibiting autophagy. Anti-miR-21 oligonucleotides re-sensitized sorafenib-resistant cells by promoting autophagy. Inhibition of miR-21 enhances the efficacy of sorafenib in treating sorafenib-resistant HCC tumors in vivo. We conclude that miR-21 participates in the acquired resistance of sorafenib by suppresing autophagy through the Akt/PTEN pathway. MiR-21 could serve as a therapeutic target for overcoming sorafenib resistance in the treatment of HCC.

Identifying the key factor mediating pathological cardiac hypertrophy is critically important for developing the strategy to protect against heart failure. Bone morphogenetic protein-4 (BMP4) is a mechanosensitive and proinflammatory gene. In this study, we investigated the role of BMP4 in cardiac hypertrophy, apoptosis, and fibrosis in experimentally pathological cardiac hypertrophy. The in vivo pathological cardiac hypertrophy models were induced by pressure-overload and angiotensin (Ang) II constant infusion in mice, and the in vitro model was induced by Ang II exposure to cultured cardiomyocytes. The expression of BMP4 increased in pressure overload, Ang II constant infusion-induced pathological cardiac hypertrophy, but not in swimming exercise-induced physiological cardiac hypertrophy in mice. BMP4 expression also increased in Ang II–induced cardiomyocyte hypertrophy in vitro. In turn, BMP4 induced cardiomyocyte hypertrophy, apoptosis, and cardiac fibrosis, and these pathological consequences were inhibited by the treatment with BMP4 inhibitors noggin and DMH1. Moreover, Ang II–induced cardiomyocyte hypertrophy was inhibited by BMP4 inhibitors. The underlying mechanism that BMP4-induced cardiomyocyte hypertrophy and apoptosis was through increasing NADPH oxidase 4 expression and reactive oxygen species-dependent pathways. Lentivirus-mediated overexpression of BMP4 recapitulated hypertrophy and apoptosis in cultured cardiomyocytes. BMP4 inhibitor DMH1 inhibited pressure overload–induced cardiac hypertrophy in mice in vivo. The plasma BMP4 level of heart failure patients was increased compared with that of subjects without heart failure. In summary, we conclude that BMP4 is a mediator and novel therapeutic target for pathological cardiac hypertrophy.

Abstract-Cardiac hypertrophy involves a remodeling process of the heart in response to diverse pathological stimuli. Both calcineurin/nuclear factor of activated T cells pathway and microRNA-133 (miR-133) have been shown to play a critical role in cardiac hypertrophy. It has been recognized that the expression and activity of calcineurin increases and miR-133 expression decreases in the hypertrophic heart, and inhibition of calcineurin or increase of miR-133 expression protects against cardiac hypertrophy. miR-133, miR-195, miR-1, miR-208, miR-21, and so forth. 2-6 Carè et al 2 reported that the expression of microRNA-133 (miR-133) decreased in mouse and human models of cardiac hypertrophy. Overexpression of miR-133 in vitro inhibited cardiac hypertrophy. In contrast, suppression of miR-133 by "decoy" sequences induced hypertrophy. Therefore, changes of miR-133 were considered as the requisites for determining cardiac hypertrophy. Calcineurin is a calcium/calmodulin-activated serinethreonine phosphatase that dephosphorylates the transcription factor, nuclear factor of activated T cells (NFAT), which translocates into the nucleus to bind to DNA and activate hypertrophic response genes. Cardiac-specific activation of calcineurin or its downstream effector NFAT is sufficient to induce cardiac hypertrophy, 7,8 and calcineurin protein levels and phosphatase activities increase in hypertrophic hearts. 9,10 In light of the antithetical functions of calcineurin and miR-133, we hypothesized that calcineurin is the target of miR-133, and the expression of miR-133 is regulated by the calcineurin/NFAT signaling pathway.

We conclude that the beta-adrenergic pathway can stimulate expression of arrhythmogenic miR-1, contributing to ischaemic arrhythmogenesis, and beta-blockers produce their beneficial effects partially by down-regulating miR-1, which might be a novel strategy for ischaemic cardioprotection.

BACKGROUND AND PURPOSEDimethyl fumarate (DMF) is a newly approved drug for the treatment of relapsing forms of multiple sclerosis and relapsing-remitting multiple sclerosis. Here, we investigated the effects of DMF and its metabolites mono-methylfumarate (MMF and methanol) on different gastrointestinal cancer cell lines and the underlying molecular mechanisms involved. EXPERIMENTAL APPROACHCell viability was measured by the MTT or CCK8 assay. Protein expressions were measured by Western blot analysis. LDH release, live-and dead-cell staining, intracellular GSH levels, and mitochondrial membrane potential were examined by using commercial kits. KEY RESULTSDMF but not MMF induced cell necroptosis, as demonstrated by the pharmacological tool necrostatin-1, transmission electron microscopy, LDH and HMGB1 release in CT26 cells. The DMF-induced decrease in cellular GSH levels as well as cell viability and increase in reactive oxygen species (ROS) were inhibited by co-treatment with GSH and N-acetylcysteine (NAC) in CT26 cells. DMF activated JNK, p38 and ERK MAPKs in CT26 cells and JNK, p38 and ERK inhibitors partially reversed the DMF-induced decrease in cell viability. GSH or NAC treatment inhibited DMF-induced JNK, p38, and ERK activation in CT26 cells. DMF but not MMF increased autophagy responses in SGC-7901, HCT116, HT29 and CT26 cancer cells, but autophagy inhibition did not prevent the DMF-induced decrease in cell viability. CONCLUSION AND IMPLICATIONSDMF but not its metabolite MMF induced necroptosis in colon cancer cells through a mechanism involving the depletion of GSH, an increase in ROS and activation of MAPKs. BJP

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