XPD Functions as a Tumor Suppressor and Dysregulates Autophagy in Cultured HepG2 Cells

Gene variations related to the hepatocellular carcinoma: Results from a field synopsis and Bayesian revaluation

Hepatocellular carcinoma (HCC) is considered as the second cause of cancer-related deaths worldwide. Genetic variations are associated with HCC risk, an issue that has been the subject of several meta-analyses. However, meta-analyses have an important limitation on the likelihood of false positive data. Henceforth, this study aimed to assess the level of noteworthiness in the meta-analyses by means of a Bayesian approach. A systematic search was performed for meta-analyses with associations between gene polymorphisms and HCC. The calculations for the False-Positive Rate Probability (FPRP) and the Bayesian False Discovery Probability (BFDP) were performed to assess the noteworthiness with a statistical power of 1.2 and 1.5 of Odds Ratio at a prior probability of 10^-3 and 10^-5. The quality of studies was evaluated by the Venice criteria. As additional analyses, the gene-gene and protein-protein networks were designed for these genes and products. As results, we found 33 meta-analytic studies on 45 polymorphisms occurring in 35 genes. A total of 1,280 values for FPRP and BFDP were obtained. Seventy-five for FPRP (5.86%) and 95 for BFDP (14.79%) were noteworthy. In conclusion, the polymorphisms in CCND1, CTLA4, EGF, IL6, IL12A, KIF1B, MDM2, MICA, miR-499, MTHFR, PNPLA3, STAT4, TM6SF2, and XPD genes were considered as noteworthy biomarkers for HCC risk.

Sphingomyelinases and Liver Diseases

Sphingolipids (SLs) are critical components of membrane bilayers that play a crucial role in their physico-chemical properties. Ceramide is the prototype and most studied SL due to its role as a second messenger in the regulation of multiple signaling pathways and cellular processes. Ceramide is a heterogeneous lipid entity determined by the length of the fatty acyl chain linked to its carbon backbone sphingosine, which can be generated either by de novo synthesis from serine and palmitoyl-CoA in the endoplasmic reticulum or via sphingomyelin (SM) hydrolysis by sphingomyelinases (SMases). Unlike de novo synthesis, SMase-induced SM hydrolysis represents a rapid and transient mechanism of ceramide generation in specific intracellular sites that accounts for the diverse biological effects of ceramide. Several SMases have been described at the molecular level, which exhibit different pH requirements for activity: neutral, acid or alkaline. Among the SMases, the neutral (NSMase) and acid (ASMase) are the best characterized for their contribution to signaling pathways and role in diverse pathologies, including liver diseases. As part of a Special Issue (Phospholipases: From Structure to Biological Function), the present invited review summarizes the physiological functions of NSMase and ASMase and their role in chronic and metabolic liver diseases, of which the most relevant is nonalcoholic steatohepatitis and its progression to hepatocellular carcinoma, due to the association with the obesity and type 2 diabetes epidemic. A better understanding of the regulation and role of SMases in liver pathology may offer the opportunity for novel treatments of liver diseases.

Gender Differential Transcriptome in Gastric and Thyroid Cancers

Cancer has an important and considerable gender differential susceptibility confirmed by several epidemiological studies. Gastric (GC) and thyroid cancer (TC) are examples of malignancies with a higher incidence in males and females, respectively. Beyond environmental predisposing factors, it is expected that gender-specific gene deregulation contributes to this differential incidence. We performed a detailed characterization of the transcriptomic differences between genders in normal and tumor tissues from stomach and thyroid using Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) data. We found hundreds of sex-biased genes (SBGs). Most of the SBGs shared by normal and tumor belong to sexual chromosomes, while the normal and tumor-specific tend to be found in the autosomes. Expression of several cancer-associated genes is also found to differ between sexes in both types of tissue. Thousands of differentially expressed genes (DEGs) between paired tumor-normal tissues were identified in GC and TC. For both cancers, in the most susceptible gender, the DEGs were mostly under-expressed in the tumor tissue, with an enrichment for tumor-suppressor genes (TSGs). Moreover, we found gene networks preferentially associated to males in GC and to females in TC and correlated with cancer histological subtypes. Our results shed light on the molecular differences and commonalities between genders and provide novel insights in the differential risk underlying these cancers.

XPD inhibits cell growth and invasion and enhances chemosensitivity in esophageal squamous cell carcinoma by regulating the PI3K/AKT signaling pathway

Esophageal squamous cell carcinoma (ESCC) is a lethal disease due to its high aggressiveness. The aim of the present study was to investigate the role of xeroderma pigmentosum complementation group D (XPD) in the growth and invasion of ESCC and to elucidate the potential underlying molecular mechanisms. Western blot analysis and RT-qPCR were used to detect the expression level of XPD in ESCC tissue samples and adjacent normal esophageal tissue samples. The pEGFP-N2/XPD plasmid was transfected into human ESCC cell lines (EC9706 and EC109). The proliferation, apoptosis, migration and invasion of EC9706 or EC109 cells were assessed following transfection with the XPD overexpression plasmid. The chemosensitivity of EC9706 or EC109 cells to cisplatin or fluorouracil was evaluated by CCK-8 assay. The expression levels of phosphoinositide 3-kinase (PI3K)/AKT, nuclear factor (NF)-κB, Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase (MAPK) signaling pathway-related genes were detected by RT-qPCR and western blot analysis. The results demonstrated that the expression level of XPD was markedly lower in ESCC tissue samples than in adjacent normal esophageal tissue samples. The pEGFP-N2/XPD plasmid was successfully transfected into EC9706 or EC109 cells, inducing XPD overexpression. A High XPD expression markedly suppressed cell proliferation, migration and invasion, and increased the apoptotic rate of EC9706 and EC109 cells. Furthermore, the overexpression of XPD significantly increased the chemosensitivity of EC9706 and EC109 cells to cisplatin or fluorouracil. Following XPD overexpression, the expression levels of PI3K, p-AKT, c-Myc, Cyclin D1, Bcl-2, vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9 were markedly downregulated, while the expression level of p21 was markedly upregulated. On the whole, the findings of the present study demonstrate that XPD inhibits the growth and invasion of EC9706 and EC109 cells, whilst also enhancing the chemosensitivity of EC9706 and EC109 cells to cisplatin or fluorouracil by regulating the PI3K/AKT signaling pathway. XPD may thus be an underlying target for ESCC treatment and drug resistance.

XPD suppresses cell proliferation and migration via miR-29a-3p-Mdm2/PDGF-B axis in HCC

Objective

The aim of this study was to investigate the role of XPD in migration and invasion of hepatocellular carcinoma (HCC) cells.

Methods

The expression of XPD and miR-29a-3p was examined by western blot and qRT-PCR, cell proliferation was detected by MTT assay, cell migration was detected by transwell assay. TargetScan was used to predict potential targets of miR-29a-3p.

Results

In this study, we found that the expression of XPD and miR-29a-3p was downregulated in HCC samples and HCC cell lines. XPD suppressed proliferation and migration of HCC cell via regulating miR-29a-3p expression. Target prediction analysis and dual-luciferase reporter assay confirmed Mdm2 and PDGF-B were direct targets of miR-29a-3p, and miR-29a-3p suppressed proliferation and migration of HCC cells via regulating the expression of Mdm2 or PDGF-B.

Conclusions

Our data indicated that XPD suppressed cell proliferation and migration via miR-29a-3p-Mdm2/PDGF-B axis in HCC.

Autophagy, NAFLD and NAFLD-Related HCC

Non-alcoholic fatty liver disease (NAFLD) will become a dominant cause of hepatocellular carcinoma (HCC) in the coming decade. Whereas the exact molecular mechanisms underlying the progression from simple steatosis, through steatohepatitis, to HCC remains largely unclear, emerging evidence has supported a central role of defective autophagy in the pathogenesis of NAFLD and its complications. Autophagy not only regulates lipid metabolism and insulin resistance, but also protects hepatocytes from injury and cell death. Nevertheless, in inflammation and tumorigenesis, the role of autophagy is more paradoxical. In NAFLD, defective hepatic autophagy occurs at multiple levels through numerous mechanisms and is causally linked to NAFLD-related HCC. In this chapter, we summarize the regulation and function of autophagy in NAFLD and highlight recent identification of potential pharmacological agents for restoring autophagic flux in NAFLD.

Reduction of apoptosis by proanthocyanidin-induced autophagy in the human gastric cancer cell line MGC-803

Proanthocyanidins are flavonoids that are widely present in the skin and seeds of various plants, with the highest content in grape seeds. Many experiments have shown that proanthocyanidins have antitumor activity both in vivo and in vitro. Autophagy and apoptosis of tumor cells induced by drugs are two of the major causes of tumor cell death. However, reports on the effect of autophagy induced by drugs in tumor cells are not consistent and suggest that autophagy can have synergistic or antagonistic effects with apoptosis. This research was aimed at investigating whether proanthocyanidins induced autophagy and apoptosis in human gastric cancer cell line MGC-803 cells and to identify the mechanism of proanthocyanidins action to further determine the effect of proanthocyanidins-induced autophagy on apoptosis. MTT assay was used to examine the proanthocyanidin cytotoxicity against human gastric cancer cell line MGC-803. Transmission electron microscopy and monodansylcadaverine (MDC) staining were used to detect autophagy. Annexin V APC/7-AAD double staining and Hoechst 33342/propidium iodide (PI) double staining were used to explore apoptosis. Western blotting was used to determine expression of proteins related to autophagy and apoptosis. Real-time quantitative PCR technology was used to determine the mRNA level of Beclin1 and BCL-2. The results showed that proanthocyanidins exhibit a significant inhibitory effect on the human gastric cancer cell line MGC-803 proliferation in vitro and simultaneously activate autophagy and apoptosis to promote cell death. Furthermore, when proanthocyanidin-induced autophagy is inhibited, apoptosis increases significantly, proanthocyanidins can be used together with autophagy inhibitors to enhance cytotoxicity.