Cell metabolism pathways involved in the pathophysiological changes of diabetic peripheral neuropathy

Diabetic peripheral neuropathy is a common complication of diabetes mellitus.Elucidating the pathophysiological metabolic mechanism impels the generation of ideal therapies.However,existing limited treatments for diabetic peripheral neuropathy expose the urgent need for cell metabolism research.Given the lack of comprehensive understanding of energy metabolism changes and related signaling pathways in diabetic peripheral neuropathy,it is essential to explore energy changes and metabolic changes in diabetic peripheral neuropathy to develop suitable treatment methods.This review summarizes the pathophysiological mechanism of diabetic peripheral neuropathy from the perspective of cellular metabolism and the specific interventions for different metabolic pathways to develop effective treatment methods.Various metabolic mechanisms(e.g.,polyol,hexosamine,protein kinase C pathway)are associated with diabetic peripheral neuropathy,and researchers are looking for more effective treatments through these pathways.

TUMOR NECROSIS FACTOR－α ALTERS PROTEINMETABOLISM AND CELL－CYCLE KINETICSIN MALIGNANT TUMOR

The effects of tumor necrosis factor-α(TNF) on protein metabolism and cell-cycle kinetics were investigated in malignant tumor. Sprague-Dawley rats, subcutaneously inoculated with Walker 256 carcinosarcoma,were injected intraperitoneally with recombinant human TNF at a dose of 4-75×106 U/kg for 3 consecutive days.Tumor protein metabolism and cell-cycle kinetics were analyzed. The results showed a significant decrease in tumor volume and weight in comparison with control.TNF resulted in significant decrease in tumor Protein fractional synthesis rate, Protein synthesis and fractional growth rate, but no change of tumor protein fractional degradation rate. TNF also resulted in remarkable decline in labelling index and GI phase increase of tumor cells, 6 hours after bromodeoxyuridine injection, by cytometry. The results indicated that TNF inhibits tumor growth as a result of decreases in tumor cell DNA and protein syntheses.

The Experimental and Clinical Study on the Effect of Curcumin on Cell Cycle Proteins and Regulating Proteins of Apoptosis in Acute Myelogenous Leukemia

To investigate whether the Bcl- 2 gene family is involved in m odulating mechanism of apoptosis and change of cell cycle protein induced by curcumin in acute myeloid leukemia HL - 6 0 cell line and primary acute m yelogenous leukem ic cells,the Bcl- 2 family member Mcl- 1,Bax and Bak and cell cycle proteins including P2 7kipl,P2 1wafl,cyclin D3and p Rbp- were selected and their ex- pression detected by SABC imm uno- histochem ical stain m ethod.The attitude of sub- G1 peak in DNA histogram was determined by FCM.The TU NEL positive cell percentage was identified by term inal deoxynucleotidyl transferase (Td T ) - m ediated Biotin d U NP end labeling technique.It was found that when HL - 6 0 cells were treated with 2 5μm ol/ L curcumin for 2 4 h,the expression level of Mcl- 1was down- regulated,but that of Bax and Bak up- regulated time- dependently.There was significant difference in the expression level of Mcl- 1,Bax and Bak between the curcumin- treated groups and control group(P<0 .0 5 - 0 .0 1) .At the sam e time,curcumin had no effect on progress of cell cycle in prim aty acute m yelogenous leukemia at newly diagnosis,but could in- crease the peak of Sub- G1 (P<0 .0 5 ) ,and down- regulate the expression of Mcl- 1and up- regulate the expression of Bax and Bak with the difference being statistically significant.The expression of P2 7kipl,P2 1wafl and p Rbp- were elevated and thatof cyclin D3decreased in the presence of curcum in. These findings suggested thatthe Bcl- 2 gene fam ily indeed participated in the regulatory process of apoptosis induced by curcumin in HL - 6 0 cells and AML cells.Curcumin can induce apoptosis of primary acute myelogenous leukemic cells and disturb cell cycle progression of HL - 6 0 cells.The m echanism appeared to be m ediated by perturbing G0 / G1 phases checkpoints which associated with up- regulation of P2 7kipl,P2 1wafl and p Rbp- expression,and down- regulation of cyclin D3.

Inhibitory Effects of NO-Fluvastatin on Proliferation of Human Lens Epithelial Cells in vitro by Modulating Cell Cycle Regulatory Proteins

The effects of NO-Fluvastatin on proliferation of human lens epithelial cells （HLECs） and the action mechanism were investigated. Cell proliferation was assessed by MTT assay. Cell cycle was analyzed by flow cytometry. The expression of cell cycle regulatory proteins CyclinE mRNA and P21waf1 mRNA was detected by reverse transcription polymerase chain reaction （RT-PCR）. MTT staining colorimetry showed that HLECs proliferation was markedly inhibited by NO-Fluvastatin and the effect was dependently related to time （24, 48 and 72 h） and dosage （1, 5 and 20 μmol/L）. Flow cytometry revealed that NO-Fluvastatin could significantly block HLECs in the G0/G1 phase, resulting in the increased cells in the G0/G1 phase and decreased in the S phase （P〈0.05）. RT-PCR showed that NO-Fluvastatin could obviously inhibit the CyclinE mRNA expression and induce the P21waf1 mRNA expression as compared with the negative control groups （P〈0.05）. This experiment suggested that NO-Fluvastatin could suppress the proliferation of HLECs by regulating cell cycle regulatory proteins （inhibiting the expression of CyclinE mRNA and inducing the expression of P21waf1 mRNA）, resulting in the arrest of HLECs in the G0/G1 phase, which can offer theory basis for NO-Fluvastatin in treating posterior capsular opacification in clinic practice.

Astrocytic endothelin-1 overexpression impairs learning and memory ability in ischemic stroke via altered hippocampal neurogenesis and lipid metabolism

Vascular etiology is the second most prevalent cause of cognitive impairment globally.Endothelin-1,which is produced and secreted by endothelial cells and astrocytes,is implicated in the pathogenesis of stroke.However,the way in which changes in astrocytic endothelin-1 lead to poststroke cognitive deficits following transient middle cerebral artery occlusion is not well understood.Here,using mice in which astrocytic endothelin-1 was overexpressed,we found that the selective overexpression of endothelin-1 by astrocytic cells led to ischemic stroke-related dementia(1 hour of ischemia;7 days,28 days,or 3 months of reperfusion).We also revealed that astrocytic endothelin-1 overexpression contributed to the role of neural stem cell proliferation but impaired neurogenesis in the dentate gyrus of the hippocampus after middle cerebral artery occlusion.Comprehensive proteome profiles and western blot analysis confirmed that levels of glial fibrillary acidic protein and peroxiredoxin 6,which were differentially expressed in the brain,were significantly increased in mice with astrocytic endothelin-1 overexpression in comparison with wild-type mice 28 days after ischemic stroke.Moreover,the levels of the enriched differentially expressed proteins were closely related to lipid metabolism,as indicated by Kyoto Encyclopedia of Genes and Genomes pathway analysis.Liquid chromatography-mass spectrometry nontargeted metabolite profiling of brain tissues showed that astrocytic endothelin-1 overexpression altered lipid metabolism products such as glycerol phosphatidylcholine,sphingomyelin,and phosphatidic acid.Overall,this study demonstrates that astrocytic endothelin-1 overexpression can impair hippocampal neurogenesis and that it is correlated with lipid metabolism in poststroke cognitive dysfunction.

Effects of estradiol on cell cycle and cyclin proteins of vascular smooth muscle cells in rats

To study the effects of 17β-estradiol(E2) on the growth of cultured rat vascular smooth muscle cells (VSMC).Methods The cell cycle and the expressions of Cyclin D1 and CDK4 proteins were examined by flow cytometry in VSMC cultured in different concentrations (0～100 nmol/L) of 17β-estradiol with or without serum.Results Under serum-stimulating conditions,17β-estradiol(1,10,100 nmol/L) promoted VSMC proliferation by accelerating their cell cycle progression from G1 to S phases,and the cell rates at S were (31.89±9.14)%(35.90±4.59)% and (30.77±1.20)% respectively,significantly higher than the corresponding values of control cells (21.63±1.80)%.This was accompanied by the significantly increased expression of Cyclin D1 and CDK4 proteins.In the cultures without serum,however,high concentrations (10,100 nmol/L) of E2 induced a cell cycle arrest at G1 phase,which was characterizsed by decreased cell rates at S phase [(9.93±1.43)% and (8.76±1.80)% respectively,P<0.05] as compared with the corresponding control values and a down-regulation of expressions of Cyclin D1 and CDK4 proteins.Conclusion E2 can either promote or inhibit VSMC proliferation depending upon the presence or absence of serum mitogens.The underlying mechanism may be associated with the hormone’s action on the expression of Cyclin D1 and CDK4 which act as the G1 phase regulators.4 refs.

Expression of p27Kip1, A Cell Cycle Repressor Protein with Dual Roles for Both Cancer Prevention and Promotion, Is Regulated Primarily at the Level of Unusual p27Kip1 mRNA—A Short Concept Proposal

The p27Kip1 is a cell cycle repressor protein that regulates primarily the cell cycle transition from G1 to S phase and hence the DNA replication is in the S phase and cell division in the M phase. Expression of p27Kip1 protein has dual roles for both cancer prevention and promotion. For example, numerous nutritional and chemopreventive anti-cancer agents specifically increase the expression of p27Kip1 protein without directly affecting the expression of any other cell cycle regulatory proteins. On the other hand, pro-cancer agents (like glucose, insulin and other growth factors frequently seen in obesity and/or diabetes) specifically decrease the expression of p27Kip1 protein without directly affecting the expression of any other cell cycle regulatory proteins. Unlike expression of any other cell cycle regulatory proteins, expression of p27Kip1 protein is very unusual. The mRNA of p27Kip1 has a very long and unusual 5’-untranslated region (from -575 to -1 in human). It appears that the 5’-untranslated region of p27Kip1 mRNA forms two alternative secondary structures. One increases the expression of p27Kip1 protein when anti-cancer agents are added and another decrease the expression of p27K1p1 when pro-cancer agents are added. For this short concept proposal, Dr. Albert Einstein’s “visualized thought experiments (German: Gedanken experiment)” were used as a fundamental tool for understanding how either anti- or pro-cancer agents bring the primary structure of the 5’-untranslated region of p27Kip1 mRNA into two alternative secondary structures, thereby either increasing or decreasing, respectively, the translation initiation of p27Kip1 protein.

Lower Concentrations of Glucose or Insulin Decrease the Risk of Various Types of Cancer in the Long-Lived Ames Dwarf Mouse by Increasing the Expression of p27Kip1, a Cell-Cycle Repressor Protein

Introduction. The molecular biological mechanism of the increased incidence of the various types of cancer in obesity or type 2 diabetes in rodents or humans has largely been resolved in recent years. By contrast, the molecular biological mechanism of the decreased, not increased, incidence of the various types of cancer in the homozygous long-lived Ames dwarf mice still remains unresolved. Objective. The first objective of the present study was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the increase, not decrease, in the expression of p27Kip1, a cell cycle repressor protein. The second objective was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the decrease, not increase, in the levels of glucose or insulin. Methods. To achieve these objectives, we first performed western immunoblot analysis of the hepatic expression of p27Kip1 protein. We then performed, using a human breast cancer cell line in vitro, the luciferase reporter plasmid assay to determine whether the translation initiation activity of the p27Kip1 mRNA is increased when the concentrations of either glucose or insulin are decreased. Results and Conclusion. The results of the first objective indicated that the hepatic expression of p27Kip1 protein was up-regulated in the homozygous long-lived Ames dwarf mice as expected. We also found that the lower concentrations of glucose or insulin increased the translation initiation activity of the p27Kip1 mRNA.

Alisol B 23-acetate-induced HepG2 hepatoma cell death through mTOR signaling-initiated G_1 cell cycle arrest and apoptosis: A quantitative proteomic study

Objective: The present study aimed to investigate the molecular events in alisol B 23-acetate(ABA) cytotoxic activity against a liver cancer cell line.Methods: First, we employed a quantitative proteomics approach based on stable isotope labeling by amino acids in cell culture(SILAC) to identify the different proteins expressed in HepG2 liver cancer cells upon exposure to ABA. Next, bioinformatics analyses through DAVID and STRING on-line tools were used to predict the pathways involved. Finally, we applied functional validation including cell cycle analysis and Western blotting for apoptosis and mTOR pathway-related proteins to confirm the bioinformatics predictions.Results: We identified 330 different proteins with the SILAC-based quantitative proteomics approach. The bioinformatics analysis and the functional validation revealed that the mTOR pathway, ribosome biogenesis, cell cycle, and apoptosis pathways were differentially regulated by ABA. G1 cell cycle arrest, apoptosis and mTOR inhibition were confirmed.Conclusions: ABA, a potential mTOR inhibitor, induces the disruption of ribosomal biogenesis. It also affects the mTOR-MRP axis to cause G1 cell cycle arrest and finally leads to cancer cell apoptosis.

Deleted in liver cancer 1 suppresses the growth of prostate cancer cells through inhibiting Rho-associated protein kinase pathway

Objective:Deleted in liver cancer 1(DLC1)is a GTPase-activating protein that is reported as a suppressor in certain human cancers.However,the detailed biological function of DLC1 is still unclear in human prostate cancer(PCa).In the present study,we aimed to explore the function of DLC1 in PCa cells.Methods:Silencing and overexpression of DLC1 were induced in an androgen-sensitive PCa cell line(LNCaP)using RNA interference and lentiviral vector transduction.The Cell Counting Kit-8 assay was performed to determine cell proliferation.The cell cycle was examined by performing a propidium iodide staining assay.Results:Our results indicated that DLC1 overexpression markedly suppressed the proliferation and cell cycle progression of LNCaP cells.Moreover,DLC1 expression was negatively correlated with Rho-associated protein kinase(ROCK)expression in LNCaP cells.Importantly,this study showed that the ROCK inhibitor Y27632 restored the function of DLC1 in LNCaP cells and reduced the tumorigenicity of LNCaP cells in vivo.Conclusion:Our results indicated that DLC1 overexpression markedly suppressed the proliferation and cell cycle progression of PCa cells and negatively correlated with ROCK expression in PCa cells and tissue.

An R2R3-type transcription factor gene AtMYB59 regulates root growth and cell cycle progression in Arabidopsis

MYB 蛋白质在真核细胞的有机体起重要作用。在植物， R1R2R3 类型 MYB 蛋白质在房间周期控制工作。然而， R2R3 类型 MYB 蛋白质是否也涉及房间部门过程，仍然保持未知。这里，我们报导那 R2R3 类型抄写因素基因， AtMYB59，涉及房间周期前进和根生长的规定。AtMYB59 蛋白质在洋葱的原子核是局部性的表皮的房间并且 transactivation 活动。在酵母房间的 AtMYB59 的表示压制房间增长，和 transformants 与更长的房间有更多的原子核和更高的 aneuploid DNA 内容。在 AtMYB59 的保存领域的变化在酵母细胞生长上废除它的效果。在同步 Arabidopsis 房间暂停， AtMYB59 基因明确地在房间周期前进期间在 S 阶段被表示。表示和 promoter-GUS 分析表明 AtMYB59 基因富有地在根被表示。转基因的植物 overexpressing AtMYB59 更短的根与野类型的植物(Arabidopsis 就职 Col-0 ) 相比，并且在在根尖端的有丝分裂的房间的一半附近在中期。相反地，空变异的 myb59-1 比关口在中期让更长的根和更少有丝分裂的房间，建议那 AtMYB59 可以由扩大有丝分裂的房间的中期禁止根生长。AtMYB59 调整许多下游的基因，包括 CYCB1； 1 基因，可能通过到 MYB 应答的元素的绑定。这些结果在细胞周期规定和植物根生长为 AtMYB59 支持一个角色。

6-OHDA Induces Cycle Reentry and Apoptosis of PC12 Cells through Activation of ERK1/2 Signaling Pathway

This study investigated the effect and mechanism of cell cycle reentry induced by 6-hydrodopamine （6-OHDA） in PC12 cells. By using neural differentiated PC12 cells treated with 6-OHDA, the apoptosis model of dopaminergic neurons was established. Cell viability was measured by MTT. Cell apoptosis and the distribution of cell cycle were assessed by flow cytometry. Western blot was used to detect the activation of extracellular regulator kinasel/2 （ERK1/2） pathway and the phosphorylation of retinoblastoma protein （RB）. Our results showed that after PC12 cells were treated wtih 6-OHDA, the viability of PC12 cells was declined in a concentration-dependent manner. Flow cytornetry revealed that 6-OHDA could increase the apoptosis ratio of PC12 cells in a time-dependent manner. The percentage of ceils in G0/G1 phase of cell cycle was decreased and that in S phase and G2/M phase increased. Simultaneously, ERK1/2 pathway was activated and phosphorylated RB increased. It was concluded that 6-OHDA could induce cell cycle reentry of dopaminergic neurons through the activation of ERK1/2 pathway and RB phosphorylation. The aberrant cell cycle reentry contributes to the apoptosis of dopaminergic neurons.

Hepatitis C virus core proteins derived from different quasispecies of genotype 1b inhibit the growth of Chang liver cells

AIM: To investigate the influence of different quasispecies of hepatitis C virus (HCV) genotype 1b core protein on growth of Chang liver cells. METHODS: Three eukaryotic expression plasmids (pEGFP-N1/core) that contained different quasispecies truncated core proteins of HCV genotype 1b were constructed. These were derived from tumor (T) and non- tumor (NT) tissues of a patient infected with HCV and C191 (HCV-J6). The core protein expression plasmids were transiently transfected into Chang liver cells. At different times, the cell cycle and apoptosis was assayed by flow cytometry, and cell proliferation was assayed by methyl thiazolyl tetrazolium (MTT) assay. RESULTS: The proportion of S-phase Chang liver cells transfected with pEGFP-N1/core was significantly lower than that of cells transfected with blank plasmid at three different times after transfection (all P < 0.05). The proliferation ratio of cells transfected with pEGFP-N1/corewas significantly lower than that of cells transfected with blank plasmid. Among three different quasispecies, T, NT and C191 core expression cells, there was no significant difference in the proportion of S- and G0/G1-phase cells. The percentage of apoptotic cells was highest for T (T > NT > C191), and apoptosis was increased in cells transfected with pEGFP-N1/core as the transfection time increased (72 h > 48 h > 24 h). CONCLUSION: These results suggest that HCV genotype 1b core protein induces apoptosis, and inhibits cell- cycle progression and proliferation of Chang liver cells. Different quasispecies core proteins of HCV genotype 1b might have some differences in the pathogenesis of HCV persistent infection and hepatocellular carcinoma.

Cell cycle and complement inhibitors may be specific for treatment of spinal cord injury in aged and young mice: transcriptomic analyses

Previous studies have reported age-specific pathological and functional outcomes in young and aged patients suffering spinal cord injury,but the mechanisms remain poorly understood. In this study, we examined mice with spinal cord injury. Gene expression profiles from the Gene Expression Omnibus database （accession number GSE93561） were used, including spinal cord samples from 3 young injured mice （2–3-months old, induced by Impactor at Th9 level） and 3 control mice （2–3-months old, no treatment）, as well as 2 aged injured mice （15–18-months old, induced by Impactor at Th9 level） and 2 control mice （15–18-months old, no treatment）. Differentially expressed genes （DEGs） in spinal cord tissue from injured and control mice were identified using the Linear Models for Microarray data method,with a threshold of adjusted P 〈 0.05 and ｜logFC（fold change）｜ 〉 1.5. Protein–protein interaction networks were constructed using data from the STRING database, followed by module analysis by Cytoscape software to screen crucial genes. Kyoto encyclopedia of genes and genomes pathway and Gene Ontology enrichment analyses were performed to investigate the underlying functions of DEGs using Database for Annotation, Visualization and Integrated Discovery. Consequently, 1,604 and 1,153 DEGs were identified between injured and normal control mice in spinal cord tissue of aged and young mice, respectively. Furthermore, a Venn diagram showed that 960 DEGs were shared among aged and young mice, while 644 and 193 DEGs were specific to aged and young mice, respectively. Functional enrichment indicates that shared DEGs are involved in osteoclast differentiation, extracellular matrix–receptor interaction, nuclear factor-kappa B signaling pathway, and focal adhesion. Unique genes for aged and young injured groups were involved in the cell cycle （upregulation of PLK1） and complement （upregulation of C3） activation, respectively. These findings were confirmed by functional analysis of genes in modules （common, 4; aged, 2; young, 1） screened from protein–protein interaction networks. Accordingly, cell cycle and complement inhibitors may be specific treatments for spinal cord injury in aged and young mice, respectively.

Simultaneous recovery of dual pathways for ammonia metabolism do not improve further detoxification of ammonia in HepG2 cells

BACKGROUND:Key enzyme deficiency in the dual-pathway of ammonia metabolism leads to low detoxification capacity of HepG2 cells.Previously,we established a HepG2/AFhGS cell line with overexpression of human glutamine synthetase(hGS) in pathway 1 and a HepG2/(hArgI+hOTC)4 cell line with overexpression of human arginase I(hArgI) and human ornithine transcarbamylase(hOTC) in pathway 2.The present study aimed to investigate whether simultaneous recovery of the two pathways contributes to the further improvement of ammonia detoxification in HepG2 cells.METHODS:We adopted a recombinant retrovirus carrying the hGS gene to infect HepG2/(hArgI+hOTC)4 cells and selected a new recombinant HepG2 cell line.The capacities of ammonia tolerance and detoxification in cells were detected by biochemical methods.Cell cycle PCR chip was used to assess the changes of gene expression.RESULTS:Introducing hGS into HepG2/(hArgI+hOTC)4 cells did not lead to hGS overexpression,but inhibited hArgI expression.The levels of synthetic glutamine and urea in HepG2/(hArgI+hOTC+AFhGS)1 cells were significantly lower than those in HepG2/(hArgI+hOTC)4 cells when cultured in the medium with 10 and 15 mmol/L glutamate(Glu) and with 60 and 180 mmol/L NH 4 Cl,respectively.In addition,the comparison of different cell growth showed that HepG2/AFhGS cells significantly lagged behind the other cells by the 5th and 7th day,indicating that introduction of hGS impedes HepG2 cell proliferation.Analysis of the mechanism suggested that the decreased expression of BCL2 played an important role.CONCLUSIONS:This study demonstrated that the recovery of two ammonia metabolic pathways in HepG2 cells is not helpful in increasing ammonia metabolism.The reinforcement of the pathway of urea metabolism is more important and valuable in improving the ammonia metabolism capacity in HepG2 cells.

Prion-induced neurotoxicity: Possible role for cell cycle activity and DNA damage response

Protein misfolding neurodegenerative diseases arisethrough neurotoxicity induced by aggregation of host proteins. These conditions include Alzheimer's disease, Huntington's disease, Parkinson's disease, motor neuron disease, tauopathies and prion diseases. Collectively, these conditions are a challenge to society because of the increasing aged population and through the real threat to human food security by animal prion diseases. It is therefore important to understand the cellular and molecular mechanisms that underlie protein misfolding--induced neurotoxicity as this will form the basis for designing strategies to alleviate their burden. Prion diseases are an important paradigm for neurodegenerative conditions in general since several of these maladies have now been shown to display prion--like phenomena. Increasingly, cell cycle activity and the DNA damage response are recognised as cellular events that participate in the neurotoxic process of various neurodegenerative diseases, and their associated animal models, which suggests they are truly involved in the pathogenic process and are not merely epiphenomena. Here we review the role of cell cycle activity and the DNA damage response in neurodegeneration associated with protein misfolding diseases, and suggest that these events contribute towards prion--induced neurotoxicity. In doing so, we highlight PrP transgenic Drosophila as a tractable model for the genetic analysis of transmissible mammalian prion disease.

Effects of ethanol on hepatic cellular replication and cell cycleprogression

Ethanol is a hepatotoxin. It appears that the liver is the target of ethanol induced toxicity primarily because it is the major site of ethanol metabolism. Metabolism of ethanol results in a number of biochemical changes that are thought to mediate the toxicity associated with ethanol abuse. These include the production of acetaldehyde and reactive oxygen species, as well as an accumulation of nicotinamide adenine dinucleotide (NADH). These biochemical changes are associated with the accumulation of fat and mitochondrial dysfunction in the liver. If these changes are severe enough they can themselves cause hepatotoxicity, or they can sensitize the liver to more severe damage by other hepatotoxins. Whether liver damage is the result of ethanol metabolism or some other hepatotoxin, recovery of the liver from damage requires replacement of cells that have been destroyed. It is now apparent that ethanol metabolism not only causes hepatotoxicity but also impairs the replication of normal hepatocytes. This impairment has been shown to occur at both the G1/S, and the G2/M transitions of the cell cycle. These impairments may be the result of activation of the checkpoint kinases, which can mediate cell cycle arrest at both of these transitions. Conversely, because ethanol metabolism results in a number of biochemical changes, there may be a number of mechanisms by which ethanol metabolism impairs cellular replication. It is the goal of this article to review the mechanisms by which ethanol metabolism mediates impairment of hepatic replication.

组织中MCM7、Cyclin D1的表达与肝细胞肝癌患者1年生存时间的关系

目的研究微染色体维持蛋白7(MCM7)和细胞周期相关蛋白(Cyclin D1)与肝细胞肝癌(HCC)患者1年生存时间的关系。方法回顾性选取2020年1月至2021年6月邯郸市中心医院收治的90例原发性HCC患者。取癌组织、癌旁正常组织各2块,行免疫组织化学检查MCM7、Cyclin D1表达情况。比较癌组织及癌旁正常组织MCM7、Cyclin D1阳性检出率;观察不同临床病理特征HCC患者MCM7、Cyclin D1阳性占比情况。最后对90例HCC患者行1年院外随访,观察癌组织MCM7、Cyclin D1阳性患者术后1年存活率差异。结果癌组织内MCM7、Cyclin D1阳性检出率显著高于癌旁正常组织,差异均有统计学意义(P<0.05);不同性别、年龄、病灶数、HBsAg类型HCC患者MCM7阳性检出率比较,差异均无统计学意义(P>0.05);肿瘤直径≥5 cm、TNM分期Ⅲ~Ⅳ期、低分化、血清AFP≥400μg/L、已发生转移的HCC患者MCM7阳性检出率较高,差异均有统计学意义(P<0.05);TNM分期Ⅲ-IV期、已发生转移的HCC患者Cyclin D1阳性检出率较高,差异均有统计学意义(P<0.05)。90例行根治性手术的HCC患者均获得1年院外随访,1年病死率18.89%,存活率81.11%;64例癌组织MCM7阳性患者1年病死率25.00%,存活率75.00%,26例癌组织MCM7阴性患者中病死率3.85%,存活率96.15%,Kaplan-Meier生存分析显示癌组织MCM7阳性检出率越高患者病死率越高(Log-Rank=5.229,P=0.022);66例癌组织Cyclin D1阳性患者1年病死率24.24%,存活率75.76%,24例癌组织Cyclin D1阴性患者中病死率4.17%,存活率95.83%,Kaplan-Meier生存分析显示癌组织Cyclin D1阳性检出率越高患者病死率越高(Log-Rank=4.481,P=0.034)。结论HCC患者癌组织内MCM7、Cyclin D1表达显著增高,且MCM7、Cyclin D1与HCC病情进展有关,同时MCM7、Cyclin D1表达阳性可能会对HCC患者1年生存率造成影响。

E2FBP1 antagonizes the p16^(INK4A)-Rb tumor suppressor machinery for growth suppression and cellular senescence by regulating promyelocytic leukemia protein stability

Cellular senescence is an irreversible cell cycle arrest triggered by the activation of oncogenes or mitogenic signaling as well as the enforced expression of tumor suppressors such as p53, p16INK4A and promyelocytic leukemia protein （PML） in normal cells. E2F-binding protein 1 （E2FBP1）, a transcription regulator for E2F, induces PML reduction and suppresses the formation of PML-nuclear bodies, whereas the down-regulation of E2FBP1 provokes the PML-dependent premature senescence in human normal fibroblasts. Here we report that the depletion of E2FBP1 induces the accumulation of PML through the Ras-dependent activation of MAP kinase signaling. The cellular levels of p16INK4A and p53 are elevated during premature senescence induced by depletion of E2FBP1, and the depletion of p16INK4A, but not p53 rescued senescent cells from growth arrest. Therefore, the premature senescence induced by E2FBP1 depletion is achieved through the pl6INK4A-Rb pathway. Similar to human normal fibroblasts, the growth inhibition induced by E2FBP1 depletion is also observed in human tumor cells with intact p16INK4A and Rb. These results suggest that E2FBP1 functions as a critical antagonist to the pI6INK4A-Rb tumor suppressor machinery by regulating PML stability.

AMPK-associated signaling to bridge the gap between fuel metabolism and hepatocyte viability

The adenosine monophosphate-activated protein kinase (AMPK) and p70 ribosomal S6 kinase-1 pathway may serve as a key signaling flow that regulates energy metabolism; thus, this pathway becomes an attractive target for the treatment of liver diseases that result from metabolic derangements. In addition, AMPK emerges as a kinase that controls the redox-state and mitochondrial function, whose activity may be modulated by antioxidants. A close link exists between fuel metabolism and mitochondrial biogenesis. The relationship between fuel metabolism and cell survival strongly implies the existence of a shared signaling network, by which hepatocytes respond to challenges of external stimuli. The AMPK pathway may belong to this network. A series of drugs and therapeutic candidates enable hepatocytes to protect mitochondria from radical stress and increase cell viability, which may be associated with the activation of AMPK, liver kinase B1, and other molecules or components. Consequently, the components downstream of AMPK may contribute to stabilizing mitochondrial membrane potential for hepatocyte survival. In this review, we discuss the role of the AMPK pathway in hepatic energy metabolism and hepatocyte viability. This information may help identify ways to prevent and/or treat hepatic diseases caused by the metabolic syndrome. Moreover, clinical drugs and experimental therapeutic candidates that directly or indirectly modulate the AMPK pathway in distinct manners are discussed here with particular emphasis on their effects on fuel metabolism and mitochondrial function.