Epigenetic states and expression of imprinted genes in human embryonic stem cells

AIM: To investigate the epigenetic states and expres- sion of imprinted genes in five human embryonic stem cell (hESC) lines derived in Taiwan. METHODS: The heterozygous alleles of single nucleo- tide polymorphisms (SNPs) at imprinted genes were analyzed by sequencing genomic DNAs of hESC lines and the monoallelic expression of the imprinted genes were confirmed by sequencing the cDNAs. The expres- sion profiles of 32 known imprinted genes of five hESC lines were determined using Affymetrix human genome U133 plus 2.0 DNA microarray. RESULTS: The heterozygous alleles of SNPs at seven imprinted genes, IPW , PEG10 , NESP55 , KCNQ1 , ATP10A ,TCEB3C and IGF2 , were identified and the monoallelic expression of these imprinted genes except IGF2 were confirmed. The IGF2 gene was found to be imprinted in hESC line T2 but partially imprinted in line T3 and not imprinted in line T4 embryoid bodies. Ten imprinted genes, namely GRB10 , PEG10 , SGCE, MEST , SDHD , SN- RPN , SNURF , NDN , IPW and NESP55 , were found to be highly expressed in the undifferentiated hESC lines and down-regulated in differentiated derivatives. The UBE3A gene abundantly expressed in undifferentiated hESC lines and further up-regulated in differentiated tissues. The expression levels of other 21 imprinted genes were relatively low in undifferentiated hESC lines and five of these genes (TP73 , COPG2 , OSBPL5 , IGF2 and ATP10A ) were found to be up-regulated in differentiated tissues. CONCLUSION: The epigenetic states and expression of imprinted genes in hESC lines should be thoroughly studied after extended culture and upon differentiation in order to understand epigenetic stability in hESC lines before their clinical applications.

Hepatitis A virus infection and hepatitis A vaccination in human immunodeficiency virus-positive patients: A review

Hepatitis A virus(HAV)is one of the most common infectious etiologies of acute hepatitis worldwide.The virus is known to be transmitted fecal-orally,resulting in symptoms ranging from asymptomatic infection to fulminant hepatitis.HAV can also be transmitted through oral-anal sex.Residents from regions of low endemicity for HAV infection often remain susceptible in their adulthood.Therefore,clustered HAV infections or outbreaks of acute hepatitis A among men who have sex with men and injecting drug users have been reported in countries of low endemicity for HAV infection.The duration of HAV viremia and stool shedding of HAV may be longer in human immunodeficiency virus(HIV)-positive individuals compared to HIV-negative individuals with acute hepatitis A.Current guidelines recommend HAV vaccination for individuals with increased risks of exposure to HAV(such as from injecting drug use,oral-anal sex,travel to or residence in endemic areas,frequent clotting factor or blood transfusions)or with increased risks of fulminant disease(such as those with chronic hepatitis).The seroconversion rates following the recommended standard adult dosing schedule(2doses of HAVRIX 1440 U or VAQTA 50 U administered6-12 mo apart)are lower among HIV-positive individuals compared to HIV-negative individuals.While the response rates may be augmented by adding a booster dose at week 4 sandwiched between the first dose and the 6-mo dose,the need of booster vaccination remain less clear among HIV-positive individuals who have lost anti-HAV antibodies.

Prevalence and risk factors for Candida esophagitis among human immunodeficiency virus-negative individuals

BACKGROUND Candida esophagitis(CE) is among the commonest esophageal infections and is known as an opportunistic fungal infection mostly affecting people living with the human immunodeficiency virus(HIV).However,some medical conditions might predispose HIV-negative individuals to esophageal candidiasis.The epidemiology and associated endoscopic findings of CE among people without HIV have rarely been reported.AIM To investigate the prevalence of CE among HIV-negative persons,and determine risk factors predicting CE.METHODS Between January 2015 and December 2018,all consecutive outpatients who underwent routine esophagogastroduodenoscopy as part of health check-ups at their own expense at the Health Check-up Center of the Kaohsiung Veterans General Hospital,Taiwan,were recruited in this study.Those with positive HIV serology results were excluded.Sociodemographic and clinical characteristics including age,gender,economic status,smoking history,alcohol consumption,tea and coffee consumption,underlying diseases,body fat percentage,body mass index,endoscopic findings,and Helicobacter pylori infection status were carefully reviewed.CE was confirmed by endoscopic biopsy and pathological assessment with hematoxylin and eosin and periodic acidSchiff staining.To evaluate independent factors predicting the development of CE,we conducted a univariate analysis of clinical characteristics.The variables found to be significant via univariate analysis were subsequently included in a multivariable analysis of potential risk factors for CE development.RESULTS A total of 11802 participants were included in this study.Forty-seven(0.4%) were confirmed as having CE by pathological examination.Univariate analysis identified older age,the presence of chronic kidney disease,alcohol consumption,and steroid use(P = 0.023,< 0.001,0.033,and 0.004,respectively) as significantly associated with CE.Multivariable analysis revealed older age [adjusted odds ratio(OR) = 1.027;95%CI:1.001-1.053;P = 0.045],chronic kidney disease(adjusted OR = 13.470;95%CI:4.574-39.673;P < 0.001),alcohol consumption(adjusted OR = 2.103;95%CI:1.151-3.844;P = 0.016),and steroid use(adjusted OR = 24.255;95%CI:5.343-110.115;P < 0.001) as independent risk factors for CE development.The presence of dysphagia was associated with severe CE(P = 0.021).CONCLUSION The prevalence of CE among HIV-negative persons was 0.4% in Taiwan.Independent risk factors for CE were older age,chronic kidney disease,alcohol consumption,and steroid use.

Hepatitis B virus coinfection in human immunodeficiency virus-infected patients: A review

Hepatitis B virus(HBV)infection is a leading cause of chronic hepatitis,liver cirrhosis,and hepatocellular carcinoma worldwide.Due to the shared modes of transmission,coinfection with HBV and human immunodeficiency virus(HIV)is not uncommon.It is estimatedthat 10%of HIV-infected patients worldwide are coinfected with HBV.In areas where an HBV vaccination program is implemented,the HBV seroprevalence has declined significantly.In HIV/HBV-coinfected patients,HBV coinfection accelerates immunologic and clinical progression of HIV infection and increases the risk of hepatotoxicity when combination antiretroviral therapy(cART)is initiated,while HIV infection increases the risk of hepatitis events,cirrhosis,and end-stage liver disease related to chronic HBV infection.With the advances in antiviral therapy,concurrent,successful longterm suppression of HIV and HBV replication can be achieved in the cART era.To reduce the disease burden of HBV infection among HIV-infected patients,adoption of safe sex practices,avoidance of sharing needles and diluent,HBV vaccination and use of cART containing tenofovir disoproxil fumarate plus emtricitabine or lamivudine are the most effective approaches.However,due to HIV-related immunosuppression,using increased doses of HBV vaccine and novel approaches to HBV vaccination are needed to improve the immunogenicity of HBV vaccine among HIV-infected patients.

Zebrafish as a disease model for studying human hepatocellular carcinoma

Liver cancer is one of the world's most common cancers and the second leading cause of cancer deaths. Hepatocellular carcinoma(HCC), a primary hepatic cancer, accounts for 90%-95% of liver cancer cases. The pathogenesis of HCC consists of a stepwise process of liver damage that extends over decades, due to hepatitis, fatty liver, fibrosis, and cirrhosis before developing fully into HCC. Multiple risk factors are highly correlated with HCC, including infection with the hepatitis B or C viruses, alcohol abuse, aflatoxin exposure, and metabolic diseases. Over the last decade, genetic alterations, which include the regulation of multiple oncogenes or tumor suppressor genes and the activation of tumorigenesis-related pathways, have also been identified as important factors in HCC. Recently, zebrafish have become an important living vertebrate model organism, especially for translational medical research. In studies focusing on the biology of cancer, carcinogen induced tumors in zebrafish were found to have many similarities to human tumors. Several zebrafish models have therefore been developed to provide insight into the pathogenesis of liver cancer and the related drug discovery and toxicology, and to enable the evaluation of novel smallmolecule inhibitors. This review will focus on illustrativeexamples involving the application of zebrafish models to the study of human liver disease and HCC, through transgenesis, genome editing technology, xenografts,drug discovery, and drug-induced toxic liver injury.

Recently acquired hepatitis C virus infection among people living with human immunodeficiency virus at a university hospital in Taiwan

BACKGROUND Little is known about the engagement in hepatitis C virus(HCV)care and completion of HCV treatment in people living with human immunodeficiency virus(HIV)(PLWH)who have HCV coinfection in the Asia-Pacific region.Examining the HCV care cascade can identify barriers to the completion of HCV treatment and facilitate achievement of HCV micro-elimination in PLWH.AIM To investigate the care cascade of incident HCV infections among PLWH in Taiwan.METHODS PLWH with incident HCV infections,defined as HCV seroconversion,were retrospectively identified by sequential anti-HCV testing of all archived blood samples at National Taiwan University Hospital between 2011 and 2018.All PLWH with incident HCV infections were followed until December 31,2019.The care cascade of HCV examined included all incident HCV-infected patients,the percentages of anti-HCV antibodies detected by HIV-treating physicians in clinical care,plasma HCV RNA load tested,HCV RNA positivity diagnosed,referral to treatment assessment made,anti-HCV treatment initiated,and sustained virologic response achieved.Those who had HCV seroconversion during the interferon(IFN)era(2011–2016)and the direct-acting antiviral(DAA)era(2017–2018)were analyzed separately.The duration of HCV viremia—from the date of seroconversion to viral clearance by treatments or until the end of observation—and the incidence of sexually transmitted infections(STIs)during the HCV viremic period were estimated.RESULTS During the study period,287 of 3495(8.2%)PLWH(92.3%being men who have sex with men)who were HCV-seronegative at baseline developed HCV seroconversion by retrospective testing of all archived blood samples.Of the 287 incident HCV infections,277(96.5%)had anti-HCV antibodies detected by HIV-treating physicians,270(94.1%)had plasma HCV RNA determined and 251(87.5%)tested positive for HCV RNA.Of those with HCV viremia,226(78.7%)were referred to treatment assessment,215(74.9%)initiated anti-HCV treatment,and 202(70.4%)achieved viral clearance.Compared with that in the IFN era,the median interval from HCV seroconversion by retrospective testing to detection of HCV seropositivity by HIV-treating physicians was significantly shorter in the DAA era{179 d[interquartile range(IQR)87-434]vs 92 d(IQR 57-173);P<0.001}.The incidence rate of STIs in the DAA vs the IFN era was 50.5 per 100 person-years of follow-up(PYFU)and 38.5 per 100 PYFU,respectively,with an incidence rate ratio of 1.31(95%confidence interval 0.96-1.77),while the duration of HCV viremia was 380 d(IQR 274-554)and 735 d(IQR 391-1447)(P<0.001),respectively.CONCLUSION While anti-HCV therapies are effective in achieving viral clearance,our study suggests more efforts are needed to expedite the linkage of PLWH diagnosed with incident HCV infections to HCV treatment.

When fats commit crimes: fatty acid metabolism, cancer stemness and therapeutic resistance

The role of fatty acid metabolism,including both anabolic and catabolic reactions in cancer has gained increas-ing attention in recent years.Many studies have shown that aberrant expression of the genes involved in fatty acid synthesis or fatty acid oxidation correlate with malignant phenotypes including metastasis,therapeutic resistance and relapse.Such phenotypes are also strongly associated with the presence of a small percentage of unique cells among the total tumor cell population.This distinct group of cells may have the ability to self-renew and propagate or may be able to develop resistance to cancer therapies independent of genetic alterations.Therefore,these cells are referred to as cancer stem cells/tumor-initiating cells/drug-tolerant persisters,which are often refractory to cancer treatment and difficult to target.Moreover,interconversion between cancer cells and cancer stem cells/tumor-initiating cells/drug-tolerant persisters may occur and makes treatment even more challenging.This review highlights recent findings on the relationship between fatty acid metabolism,cancer stemness and therapeutic resistance and prompts discussion about the potential mechanisms by which fatty acid metabolism regulates the fate of cancer cells and therapeutic resistance.

Targeting the insulin-like growth factor-1 receptor in MTAP-deficient renal cell carcinoma

Renal cell carcinoma(RCC)has emerged as a metabolic disease characterized by dysregulated expression of metabolic enzymes.Patients with metastatic RCC have an unusually poor prognosis and near-universal resistance to all current therapies.To improve RCC treatment and the survival rate of patients with RCC,there is an urgent need to reveal the mechanisms by which metabolic reprogramming regulates aberrant signaling and oncogenic progression.Through an integrated analysis of RCC metabolic pathways,we showed that methylthioadenosine phosphorylase(MTAP)and its substrate methylthioadenosine(MTA)are dysregulated in aggressive RCC.A decrease in MTAP expression was observed in RCC tissues and correlated with higher tumor grade and shorter overall survival.Genetic manipulation of MTAP demonstrated that MTAP expression inhibits the epithelial-mesenchymal transition,invasion and migration of RCC cells.Interestingly,we found a decrease in the protein methylation level with a concomitant increase in tyrosine phosphorylation after MTAP knockout.A phospho-kinase array screen identified the type 1 insulin-like growth factor-1 receptor(IGF1R)as the candidate with the highest upregulation in tyrosine phosphorylation in response to MTAP loss.We further demonstrated that IGF1R phosphorylation acts upstream of Src and STAT3 signaling in MTAP-knockout RCC cells.IGF1R suppression by a selective inhibitor of IGF1R,linsitinib,impaired the cell migration and invasion capability of MTAP-deleted cells.Surprisingly,an increase in linsitinib-mediated cytotoxicity occurred in RCC cells with MTAP deficiency.Our data suggest that IGF1R signaling is a driver pathway that contributes to the aggressive nature of MTAP-deleted RCC.