G. Tao

SIRT1 and c-Myc promote liver tumor cell survival and predict poor survival of human hepatocellular carcinomas.

The increased expression of SIRT1 has recently been identified in numerous human tumors and a possible correlation with c-Myc oncogene has been proposed. However, it remains unclear whether SIRT1 functions as an oncogene or tumor suppressor. We sought to elucidate the role of SIRT1 in liver cancer under the influence of c-Myc and to determine the prognostic significance of SIRT1 and c-Myc expression in human hepatocellular carcinoma. The effect of either over-expression or knock down of SIRT1 on cell proliferation and survival was evaluated in both mouse and human liver cancer cells. Nicotinamide, an inhibitor of SIRT1, was also evaluated for its effects on liver tumorigenesis. The prognostic significance of the immunohistochemical detection of SIRT1 and c-Myc was evaluated in 154 hepatocellular carcinoma patients. SIRT1 and c-Myc regulate each other via a positive feedback loop and act synergistically to promote hepatocellular proliferation in both mice and human liver tumor cells. Tumor growth was significantly inhibited by nicotinamide in vivo and in vitro. In human hepatocellular carcinoma, SIRT1 expression positively correlated with c-Myc, Ki67 and p53 expression, as well as high á-fetoprotein level. Moreover, the expression of SIRT1, c-Myc and p53 were independent prognostic indicators of hepatocellular carcinoma. In conclusion, this study demonstrates that SIRT1 expression supports liver tumorigenesis and is closely correlated with oncogenic c-MYC expression. In addition, both SIRT1 and c-Myc may be useful prognostic indicators of hepatocellular carcinoma and SIRT1 targeted therapy may be beneficial in the treatment of hepatocellular carcinoma.

Augmented Wnt signaling as a therapeutic tool to prevent ischemia/reperfusion injury in liver: Preclinical studies in a mouse model

The Wnt signaling pathway has established biological roles in liver development, regeneration, and carcinogenesis. Given the common need for cellular energy utilization in each of these processes, we hypothesized that Wnt signaling would directly regulate hepatocyte mitochondrial function. Mice were engineered to overexpress Wnt1 in hepatocytes under the control of a tetracycline analogue. Wnt1 and wild‐type mice underwent ischemia/reperfusion injury (IRI) to induce oxidative mitochondrial injury. Alpha mouse liver 12 (AML12) hepatocytes were exposed to Wnt agonists for in vitro hypoxia/reoxygenation (H‐R) experiments. We observed stabilized mitochondrial membrane potential and reduced levels of hepatocyte apoptosis involving the mitochondrial pathway in Wnt1 mice compared to controls following IRI. Wnt1 mice also demonstrated increased mitochondrial DNA copy number, as well as an increased tricarboxylic acid cycle activity and adenosine triphosphate levels indicating that mitochondrial function is preserved by Wnt1 overexpression following IRI. AML12 cells treated by Wnt3a or the glycogen synthase kinase 3β inhibitor LiCl exposed to H‐R demonstrated decreased reactive oxygen species and reduced apoptosis compared to controls. Increased nucleus‐localized PGC‐1α and phosphorylated SIRT1 was observed in both Wnt1+ mice as well as AML12 cells treated with Wnt3a or LiCl. Activated Wnt signaling protects hepatocytes against oxidative injury and apoptosis through mitochondrial stabilization and preserved oxidative phosphorylation function. Mechanistically, these effects are accompanied by an increase in phosphorylated SIRT1 and nucleus‐localized PGC‐1α. These findings expand the understanding of Wnt signaling biology in hepatocytes and suggest the potential for the therapeutic application of Wnt pathway manipulation in a variety of clinical applications including organ transplantation. Liver Transpl 21:1533‐1542, 2015.

Intestinal involvement during 3,5-diethoxycarbonyl-1,4-dihydrocollidine-induced chronic liver injury in a mouse model

PURPOSEnAlthough a physiologic relationship between intestinal mucosal integrity and hepatic function has been previously described, the effect of primary liver disease on intestinal mucosal homeostasis has not been previously well documented. In the current study, we studied the effects of chronic liver injury as a primary injury on enterocyte turnover (proliferation and apoptosis) in a mouse model.nnnMETHODSnThe liver toxin 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-enriched diet was used to induce chronic cholestatic liver injury in mice. Livers and intestine were harvested after 3 weeks of dietary treatment of histologic analysis and a determination of cell proliferation (immunohistochemistry for Ki67), or apoptosis (immunohistochemistry for caspase-3), as well as a determination of Wnt/β-catenin signaling activity.nnnRESULTSnAll DDC-fed animals exhibited histologic evidence of liver damage that was associated with the expansion of atypical ductal proliferation near the periportal areas and increased oxidative stress. In the intestine, DDC-induced liver damage was associated with decreased villus height, decreased enterocyte proliferation, and increased cell apoptosis compared with control animals. There was also evidence for decreased β-catenin expression by immunostaining in crypt and villus cells of DDC-fed mice compared with control animals.nnnCONCLUSIONnPrimary liver injury and cholestasis is associated with intestinal mucosal hypoplasia. Decreased cell proliferation and increased cell apoptosis may be responsible for decreased intestinal epithelial cell mass. The observed decrease in cell turnover is accompanied by an alteration in Wnt/β-catenin signaling.

FAM83H is involved in the progression of hepatocellular carcinoma and is regulated by MYC

Recently, the roles of FAM83H in tumorigenesis have been interested and increased expression of FAM83H and MYC in hepatocellular carcinoma (HCC) have been reported. Therefore, we investigated the expression and role of FAM83H in 163 human HCCs and further investigated the relationship between FAM83H and oncogene MYC. The expression of FAM83H is elevated in liver cancer cells, and nuclear expression of FAM83H predicted shorter survival of HCC patients. In HLE and HepG2 HCC cells, knock-down of FAM83H inhibited proliferation and invasive activity of HCC cells. FAM83H induced expression of cyclin-D1, cyclin-E1, snail and MMP2 and inhibited the expression of P53 and P27. In hepatic tumor cells derived from Tet-O-MYC mice, the expression of mRNA and protein of FAM83H were dependent on MYC expression. Moreover, a chromatin immunoprecipitation assay demonstrated that MYC binds to the promotor of FAM83H and that MYC promotes the transcription of FAM83H, which was supported by the results of a dual-luciferase reporter assay. In conclusion, we present an oncogenic role of FAM83H in liver cancer, which is closely associated with the oncogene MYC. In addition, our results suggest FAM83H expression as a poor prognostic indicator of HCC patients.

Pilot Application of Magnetic Nanoparticle-Based Biosensor for Necrotizing Enterocolitis.

BACKGROUNDnNecrotizing Enterocolitis (NEC) is a major source of neonatal morbidity and mortality. There is an ongoing need for a sensitive diagnostic instrument to discriminate NEC from neonatal sepsis. We hypothesized that magnetic nanopartile-based biosensor analysis of gut injury-associated biomarkers would provide such an instrument.nnnSTUDY DESIGNnWe designed a magnetic multiplexed biosensor platform, allowing the parallel plasma analysis of C-reactive protein (CRP), matrix metalloproteinase-7 (MMp7), and epithelial cell adhesion molecule (EpCAM). Neonatal subjects with sepsis (n=5) or NEC (n=10) were compared to control (n=5) subjects to perform a proof of concept pilot study for the diagnosis of NEC using our ultra-sensitive biosensor platform.nnnRESULTSnOur multiplexed NEC magnetic nanoparticle-based biosensor platform was robust, ultrasensitive (Limit of detection LOD: CRP 0.6 pg/ml; MMp7 20 pg/ml; and EpCAM 20 pg/ml), and displayed no cross-reactivity among analyte reporting regents. To gauge the diagnostic performance, bootstrapping procedure (500 runs) was applied: MMp7 and EpCAM collectively differentiated infants with NEC from control infants with ROC AUC of 0.96, and infants with NEC from those with sepsis with ROC AUC of 1.00. The 3-marker panel comprising of EpCAM, MMp7 and CRP had a corresponding ROC AUC of 0.956 and 0.975, respectively.nnnCONCLUSIONnThe exploration of the multiplexed nano-biosensor platform shows promise to deliver an ultrasensitive instrument for the diagnosis of NEC in the clinical setting.