Repression of YEATS2 induces cellular senescence in hepatocellular carcinoma and inhibits tumor growth.

Hepatocellular carcinoma (HCC) stands as the third leading cause of cancer-related fatalities globally. In this study, we observed a significant increase in the expression level of the YEATS2 gene in HCC patients, and it is negatively correlated with the patients' survival rate. While we have previously identified the association between YEATS2 and the survival of pancreatic cancer cells, the regulatory mechanisms and significance in HCC are still to be fully elucidated. Our study shows that knockdown (KD) of YEATS2 expression leads to DNA damage, which in turn results in an upregulation of γ-H2A.X expression and activation of the canonical senescence-related pathway p53/p21Cip1. Moreover, our transcriptomic analysis reveals that YEATS2 KD cells can enhance the expression of p21Cip1 via the c-Myc/miR-93-5p pathway, consequently fostering the senescence of HCC cells. The initiation of cellular senescence through dual-channel activation suggests that YEATS2 plays a pivotal regulatory role in the process of cell proliferation. Ultimately, our in vivo research utilizing a nude mouse tumor model revealed a notable decrease in both tumor volume and weight after the suppression of YEATS2 expression. This phenomenon is likely attributable to the attenuation of proliferative cell activity, coupled with a concurrent augmentation in the population of natural killer (NK) cells. In summary, our research results have supplemented the understanding of the regulatory mechanisms of HCC cell proliferation and indicated that targeting YEATS2 may potentially inhibit liver tumor growth.

ARF6 promotes hepatocellular carcinoma proliferation through activating STAT3 signaling.

BACKGROUND: Hepatocellular Carcinoma (HCC) possesses the high mortality in cancers worldwide. Nevertheless, the concrete mechanism underlying HCC proliferation remains obscure. In this study, we show that high expression of ARF6 is associated with a poor clinical prognosis, which could boost the proliferation of HCC. METHODS: Immunohistochemistry and western blotting were used to detect the expression level of ARF6 in HCC tissues. We analyzed the clinical significance of ARF6 in primary HCC patients. We estimated the effect of ARF6 on tumor proliferation with in vitro CCK8, colony formation assay, and in vivo nude mouse xenograft models. Immunofluorescence was conducted to investigate the ARF6 localization. western blotting was used to detect the cell cycle-related proteins with. Additionally, we examined the correlation between ARF6 and STAT3 signaling in HCC with western blotting, immunohistochemistry and xenograft assay. RESULTS: ARF6 was upregulated in HCC tissues compared to adjacent normal liver tissues. The increased expression of ARF6 correlated with poor tumor differentiation, incomplete tumor encapsulation, advanced tumor TNM stage and poor prognosis. ARF6 obviously promoted HCC cell proliferation, colony formation, and cell cycle progression. In vivo nude mouse xenograft models showed that ARF6 enhanced tumor growth. Furthermore, ARF6 activated the STAT3 signaling and ARF6 expression was positively correlated with phosphorylated STAT3 level in HCC tissues. Furthermore, after intervening of STAT3, the effect of ARF6 on tumor-promoting was weakened, which demonstrated ARF6 functioned through STAT3 signaling in HCC. CONCLUSIONS: Our results indicate that ARF6 promotes HCC proliferation through activating STAT3 signaling, suggesting that ARF6 may serve as potential prognostic and therapeutic targets for HCC patients.

DDR1 promotes hepatocellular carcinoma metastasis through recruiting PSD4 to ARF6.

Discoidin domain receptor 1 (DDR1) is a member of the receptor tyrosine kinase family, and its ligand is collagen. Previous studies demonstrated that DDR1 is highly expressed in many tumors. However, its role in hepatocellular carcinoma (HCC) remains obscure. In this study, we found that DDR1 was upregulated in HCC tissues, and the expression of DDR1 in TNM stage II-IV was higher than that in TNM stage I in HCC tissues, and high DDR1 expression was associated with poor prognosis. Gene expression analysis showed that DDR1 target genes were functionally involved in HCC metastasis. DDR1 positively regulated the migration and invasion of HCC cells and promoted lung metastasis. Human Phospho-Kinase Array showed that DDR1 activated ERK/MAPK signaling pathway. Mechanically, DDR1 interacted with ARF6 and activated ARF6 through recruiting PSD4. The kinase activity of DDR1 was required for ARF6 activation and its role in metastasis. High expression of PSD4 was associated with poor prognosis in HCC. In summary, our findings indicate that DDR1 promotes HCC metastasis through collagen induced DDR1 signaling mediated PSD4/ARF6 signaling, suggesting that DDR1 and ARF6 may serve as novel prognostic biomarkers and therapeutic targets for metastatic HCC.

The APC/CFZY-1/Cdc20 Complex Coordinates With OMA-1 to Regulate the Oocyte-to-Embryo Transition in Caenorhabditis elegans.

During oocyte maturation and the oocyte-to-embryo transition, key developmental regulators such as RNA-binding proteins coordinate translation of particular messenger RNA (mRNAs) and related developmental processes by binding to their cognate maternal mRNAs. In the nematode Caenorhabditis elegans, these processes are regulated by a set of CCCH zinc finger proteins. Oocyte maturation defective-1 (OMA-1) and OMA-2 are two functionally redundant CCCH zinc finger proteins that turnover rapidly during the first embryonic cell division. These turnovers are required for proper transition from oogenesis to embryogenesis. A gain-of-function mutant of OMA-1, oma-1(zu405), stabilizes and delays degradation of OMA-1, resulting in delayed turnover and mis-segregation of other cell fate determinants, which eventually causes embryonic lethality. We performed a large-scale forward genetic screen to identify suppressors of the oma-1(zu405) mutant. We show here that multiple alleles affecting functions of various anaphase promoting complex/cyclosome (APC/C) subunits, including MAT-1, MAT-2, MAT-3, EMB-30, and FZY-1, suppress the gain-of-function mutant of OMA-1. Transcriptome analysis suggested that overall transcription in early embryos occurred after introducing mutations in APC/C genes into the oma-1(zu405) mutant. Mutations in APC/C genes prevent OMA-1 enrichment in P granules and correct delayed degradation of downstream cell fate determinants including pharynx and intestine in excess-1 (PIE-1), posterior segregation-1 (POS-1), muscle excess-3 (MEX-3), and maternal effect germ-cell defective-1 (MEG-1). We demonstrated that only the activator FZY-1, but not FZR-1, is incorporated in the APC/C complex to regulate the oocyte-to-embryo transition. Our findings suggested a genetic relationship linking the APC/C complex and OMA-1, and support a model in which the APC/C complex promotes P granule accumulation and modifies RNA binding of OMA-1 to regulate the oocyte-to-embryo transition process.

ERAD deficiency promotes mitochondrial dysfunction and transcriptional rewiring in human hepatic cells.

Mitochondrial dysfunction is associated with a variety of human diseases including neurodegeneration, diabetes, nonalcohol fatty liver disease (NAFLD), and cancer, but its underlying causes are incompletely understood. Using the human hepatic cell line HepG2 as a model, we show here that endoplasmic reticulum-associated degradation (ERAD), an ER protein quality control process, is critically required for mitochondrial function in mammalian cells. Pharmacological inhibition or genetic ablation of key proteins involved in ERAD increased cell death under both basal conditions and in response to proinflammatory cytokines, a situation frequently found in NAFLD. Decreased viability of ERAD-deficient HepG2 cells was traced to impaired mitochondrial functions including reduced ATP production, enhanced reactive oxygen species (ROS) accumulation, and increased mitochondrial outer membrane permeability. Transcriptome profiling revealed widespread down-regulation of genes underpinning mitochondrial functions, and up-regulation of genes associated with tumor growth and aggression. These results highlight a critical role for ERAD in maintaining mitochondrial functional and structural integrity and raise the possibility of improving cellular and organismal mitochondrial function via enhancing cellular ERAD capacity.

The Dynamics of P Granule Liquid Droplets Are Regulated by the Caenorhabditis elegans Germline RNA Helicase GLH-1 via Its ATP Hydrolysis Cycle.

P granules are phase-separated liquid droplets that play important roles in the maintenance of germ cell fate in Caenorhabditis elegans Both the localization and formation of P granules are highly dynamic, but mechanisms that regulate such processes remain poorly understood. Here, we show evidence that the VASA-like germline RNA helicase GLH-1 couples distinct steps of its ATPase hydrolysis cycle to control the formation and disassembly of P granules. In addition, we found that the phenylalanine-glycine-glycine repeats in GLH-1 promote its localization at the perinucleus. Proteomic analyses of the GLH-1 complex with a GLH-1 mutation that interferes with P granule disassembly revealed transient interactions of GLH-1 with several Argonautes and RNA-binding proteins. Finally, we found that defects in recruiting the P granule component PRG-1 to perinuclear foci in the adult germline correlate with the fertility defects observed in various GLH-1 mutants. Together, our results highlight the versatile roles of an RNA helicase in controlling the formation of liquid droplets in space and time.

Endoplasmic Reticulum-Associated Degradation (ERAD) Has a Critical Role in Supporting Glucose-Stimulated Insulin Secretion in Pancreatic ß-Cells.

The molecular underpinnings of ß-cell dysfunction and death leading to diabetes are not fully elucidated. The objective of the current study was to investigate the role of endoplasmic reticulum-associated degradation (ERAD) in pancreatic ß-cells. Chemically induced ERAD deficiency in the rat insulinoma cell line INS-1 markedly reduced glucose-stimulated insulin secretion (GSIS). The mechanistic basis for this effect was studied in cells and mice lacking ERAD as a consequence of genetic ablation of the core ERAD protein SEL1L. Targeted disruption of SEL1L in INS-1 cells and in mouse pancreatic ß-cells impaired ERAD and led to blunted GSIS. Additionally, mice with SEL1L deletion in ß-cells were chronically hyperglycemic after birth and increasingly glucose intolerant over time. SEL1L absence caused an entrapment of proinsulin in the endoplasmic reticulum compartment in both INS-1 cells and mouse pancreatic ß-cells. Both folding-competent and folding-deficient proinsulin can physiologically interact with and be efficiently degraded by HRD1, the E3 ubiquitin ligase subunit of the ERAD complex. GSIS impairment in insulinoma cells was accompanied by a reduced intracellular Ca2+ ion level, overproduction of reactive oxygen species, and lowered mitochondrial membrane potential. Together, these findings suggest that ERAD plays a pivotal role in supporting pancreatic ß-cell function by targeting wild-type and folding-deficient proinsulin for proteosomal degradation. ERAD deficiency may contribute to the development of diabetes by affecting proinsulin processing in the ER, intracellular Ca2+ concentration, and mitochondrial function.

Whole-body aerosol exposure of cadmium chloride (CdCl2) and tetrabromobisphenol A (TBBPA) induced hepatic changes in CD-1 male mice.

Cadmium (Cd) and tetrabromobisphenol A (TBBPA) are two prevalent contaminants in e-waste recycling facilities. However, the potential adversely health effect of co-exposure to these two types of pollutants in an occupational setting is unknown. In this study, we investigated co-exposure of these two pollutants on hepatic toxicity in CD-1 male mice through a whole-body aerosol inhalation route. Specifically, mice were exposed to solvent control (5% DMSO), Cd (8µg/m(3)), TBBPA (16µg/m(3)) and Cd/TBBPA mixture for 8h/day and 6days a week for 60 days. Hepatic changes include increased organ weight, focal necrosis, and elevated levels of liver enzymes in serum. These changes were most severe in mice exposed to TBBPA, followed by Cd/TBBPA mixture and Cd. These chemicals also led to suppressed antioxidant defensive mechanisms and increased oxidative stress. Further, these chemicals induced gene expression of apoptosis-related genes, activated genes encoding for phase I detoxification enzymes and inhibited genes encoding for phase II detoxification enzymes. These findings indicate that the hepatic damages induced by subchronic aerosol exposure of Cd and TBBPA may result from the oxidative damages caused by excessive ROS production when these chemicals were metabolized in the liver.

Daily intake of polybrominated diphenyl ethers via dust and diet from an e-waste recycling area in China.

This study was designed to estimate the human risk to polybrominated diphenyl ethers (PBDEs) exposure via two main exposure routes (dust and diet) in an e-waste recycling area in southern China. A total of 134 dust samples and 129 food samples were analyzed by gas chromatography/mass spectrometry (GC/MS). The mean concentration of ΣPBDE in in-house dust (38,685ng/g dw) was higher than that in out-house dust (24,595ng/g). For food samples, the highest concentration of ΣPBDE was found in fish and shellfish (2755ng/kg ww), followed in descending order by eggs (2423ng/kg), cereals (2239ng/kg) and meat (1799ng/kg). The estimated total daily dietary intake of PBDEs was 1671ng/day for adults and 952ng/day for children. The present study indicated that dust intake was the dominant PBDE exposure route for children, and the dietary intake was the dominant PBDE exposure route for adults. Our findings revealed high PBDE concentrations in dust and food samples collected at the center of e-waste recycling area, raising significant health concerns for residents in this particular region, especially for children.