Biliary tract cancer stem cells-translational options and challenges

Management of biliary tract cancer remains challenging. Tumors show high recurrence rates and therapeutic resistance, leading to dismal prognosis and short survival. The cancer stem cell model states that a tumor is a heterogeneous conglomerate of cells, in which a certain subpopulation of cells-the cancer stem cells-possesses stem cell properties. Cancer stem cells have high clinical relevance due to their potential contributions to development, progression and aggressiveness as well as recurrence and metastasis of malignant tumors. Consequently, reliable identification of as well as pharmacological intervention with cancer stem cells is an intensively investigated and promising research field. The involvement of cancer stem cells in biliary tract cancer is likely as a number of studies demonstrated their existence and the obvious clinical relevance of several established cancer stem cell markers in biliary tract cancer models and tissues. In the present article, we review and discuss the currently available literature addressing the role of putative cancer stem cells in biliary tract cancer as well as the connection between known contributors of biliary tract tumorigenesis such as oncogenic signaling pathways, micro-RNAs and the tumor microenvironment with cancer stem cells.

Hepatocellular carcinoma: Therapeutic advances in signaling,epigenetic and immune targets

Hepatocellular carcinoma(HCC)remains a global medical burden with rising incidence due to chronic viral hepatitis and non-alcoholic fatty liver diseases.Treatment of advanced disease stages is still unsatisfying.Besides first and second generation tyrosine kinase inhibitors,immune checkpoint inhibitors have become central for the treatment of HCC.New modalities like epigenetic therapy using histone deacetylase inhibitors(HDACi)and cell therapy approaches with chimeric antigen receptor T cells(CAR-T cells)are currently under investigation in clinical trials.Development of such novel drugs is closely linked to the availability and improvement of novel preclinical and animal models and the identification of predictive biomarkers.The current status of treatment options for advanced HCC,emerging novel therapeutic approaches and different preclinical models for HCC drug discovery and development are reviewed here.

Comprehensive functional annotation of susceptibility variants identifies genetic heterogeneity between lung adenocarcinoma and squamous cell carcinoma

Although genome-wide association studies have identified more than eighty genetic variants associated with non-small cell lung cancer(NSCLC)risk,biological mechanisms of these variants remain largely unknown.By integrating a large-scale genotype data of 15581 lung adenocarcinoma(AD)cases,8350 squamous cell carcinoma(SqCC)cases,and 27355 controls,as well as multiple transcriptome and epigenomic databases,we conducted histology-specific meta-analyses and functional annotations of both reported and novel susceptibility variants.We identified 3064 credible risk variants for NSCLC,which were overrepresented in enhancer-like and promoter-like histone modification peaks as well as DNase I hypersensitive sites.Transcription factor enrichment analysis revealed that USF1 was AD-specific while CREB1 was SqCC-specific.Functional annotation and genebased analysis implicated 894 target genes,including 274 specifics for AD and 123 for SqCC,which were overrepresented in somatic driver genes(ER=1.95,P=0.005).Pathway enrichment analysis and Gene-Set Enrichment Analysis revealed that AD genes were primarily involved in immune-related pathways,while SqCC genes were homologous recombination deficiency related.Our results illustrate the molecular basis of both wellstudied and new susceptibility loci of NSCLC,providing not only novel insights into the genetic heterogeneity between AD and SqCC but also a set of plausible gene targets for post-GWAS functional experiments.