Simvastatin exerts anti-hepatitis B virus activity by inhibiting expression of minichromosome maintenance protein 7 in HepG2.2.15 cells

Can statins lessen the burden of virus mediated cancers?

BACKGROUND

Oncogenic viruses, including hepatitis B virus (HBV), hepatitis C virus (HCV), human papillomavirus (HPV), Epstein Barr virus (EBV), and Kaposi Sarcoma Herpes virus (KSHV) contribute to a significant proportion of the world's cancers. Given the sizeable burden of virus mediated cancers, development of strategies to prevent and/or treat these cancers is critical. While large population studies suggest that treatment with hydroxymethylglutaryl-CoA reductase inhibitors, commonly known as statins, may reduce the risk of many cancer types including HBV/HCV related hepatocellular carcinoma, few studies have specifically evaluated the impact of statin use in populations at risk for other types of virus mediated cancers.

MAIN BODY

Studies of populations with HBV and HCV suggest a protective, dose-dependent effect of statins on hepatocellular carcinoma risk and support the theory that statins may offer clinical benefit if used as chemoprophylactic agents to reduce liver cancer incidence. However, no population level data exists describing the impact of statins on populations with other oncogenic viral infections, such as HPV, EBV, and KSHV.

CONCLUSION

Further study of statin use in diverse, global populations with or at high risk for oncogenic viral infections is essential to determine the impact of statin therapy on virus mediated cancer risk.

Restoration of RNA helicase DDX5 suppresses hepatitis B virus (HBV) biosynthesis and Wnt signaling in HBV-related hepatocellular carcinoma

Rationale: RNA helicase DDX5 is downregulated during hepatitis B virus (HBV) replication, and poor prognosis HBV-related hepatocellular carcinoma (HCC). The aim of this study is to determine the mechanism and significance of DDX5 downregulation for HBV-driven HCC, and identify biologics to prevent DDX5 downregulation. Methods: Molecular approaches including immunoblotting, qRT-PCR, luciferase transfections, hepatosphere assays, Assay for Transposase-Accessible Chromatin sequencing (ATAC-seq), and RNA-seq were used with cellular models of HBV replication, HBV infection, and HBV-related liver tumors, as well as bioinformatic analyses of liver cancer cells from two independent cohorts. Results: We demonstrate that HBV infection induces expression of the proto-oncogenic miR17~92 and miR106b~25 clusters which target the downregulation of DDX5. Increased expression of these miRNAs is also detected in HBV-driven HCCs exhibiting reduced DDX5 mRNA. Stable DDX5 knockdown (DDX5^KD) in HBV replicating hepatocytes increased viral replication, and resulted in hepatosphere formation, drug resistance, Wnt activation, and pluripotency gene expression. ATAC-seq of DDX5^KD compared to DDX5 wild-type (WT) cells identified accessible chromatin regions enriched in regulation of Wnt signaling genes. RNA-seq analysis comparing WT versus DDX5^KD cells identified enhanced expression of multiple genes involved in Wnt pathway. Additionally, expression of Disheveled, DVL1, a key regulator of Wnt pathway activation, was significantly higher in liver cancer cells with low DDX5 expression, from two independent cohorts. Importantly, inhibitors (antagomirs) to miR17~92 and miR106b~25 restored DDX5 levels, reduced DVL1 expression, and suppressed both Wnt activation and viral replication. Conclusion : DDX5 is a negative regulator of Wnt signaling and hepatocyte reprogramming in HCCs. Restoration of DDX5 levels by miR17~92 / miR106b~25 antagomirs in HBV-infected patients can be explored as both antitumor and antiviral strategy.

Viral Induced Oxidative and Inflammatory Response in Alzheimer's Disease Pathogenesis with Identification of Potential Drug Candidates: A Systematic Review using Systems Biology Approach

Alzheimer's disease (AD) is genetically complex with multifactorial etiology. Here, we aim to identify the potential viral pathogens leading to aberrant inflammatory and oxidative stress response in AD along with potential drug candidates using systems biology approach. We retrieved protein interactions of amyloid precursor protein (APP) and tau protein (MAPT) from NCBI and genes for oxidative stress from NetAge, for inflammation from NetAge and InnateDB databases. Genes implicated in aging were retrieved from GenAge database and two GEO expression datasets. These genes were individually used to create protein-protein interaction network using STRING database (score≥0.7). The interactions of candidate genes with known viruses were mapped using virhostnet v2.0 database. Drug molecules targeting candidate genes were retrieved using the Drug- Gene Interaction Database (DGIdb). Data mining resulted in 2095 APP, 116 MAPT, 214 oxidative stress, 1269 inflammatory genes. After STRING PPIN analysis, 404 APP, 109 MAPT, 204 oxidative stress and 1014 inflammation related high confidence proteins were identified. The overlap among all datasets yielded eight common markers (AKT1, GSK3B, APP, APOE, EGFR, PIN1, CASP8 and SNCA). These genes showed association with hepatitis C virus (HCV), Epstein- Barr virus (EBV), human herpes virus 8 and Human papillomavirus (HPV). Further, screening of drugs targeting candidate genes, and possessing anti-inflammatory property, antiviral activity along with a suggested role in AD pathophysiology yielded 12 potential drug candidates. Our study demonstrated the role of viral etiology in AD pathogenesis by elucidating interaction of oxidative stress and inflammation causing candidate genes with common viruses along with the identification of potential AD drug candidates.

Phenotypic transition of tumor cells between epithelial- and mesenchymal-like state during adaptation to acidosis

Acidic microenvironment is an important feature of solid tumors that contributes to malignant transformation. Low extracellular pH could promote epithelial-mesenchymal transition (EMT) thereby endowing tumor cells with higher invasive capability. However, the relation between EMT and tumor cell proliferation under long-term acidic condition is still not fully understood. Here, we show that tumor cells have undergone a phenotypic transition from EMT to mesenchymal-epithelial transition (MET) during adaptation to acidosis, and is closely related with cell proliferative state. Under early stage of acidic stress, tumor cells entered a non-cycling quiescent state with mesenchymal phenotype and expressed high level of stemness genes. Whereas, after long-term acid culture (2 months), acid-adapted cells resumed proliferating but lost mesenchymal phenotype. Further, our results show that the acid-adapted cells have distinct proliferative mechanism from non-acid cells, as the G1-S transcriptional factor E2F1 protein was not recovered in the adapted cells. Meanwhile, mini-chromosome maintenance 7 (MCM7) is shown to regulate the EMT to MET phenotypic transition, and is required for proliferation of the adapted cells under acidic condition. MCM7 Knockdown promoted mesenchymal phenotype and inhibited proliferation of the acid-adapted cells. While, MCM7 overexpression inhibited acid-induced EMT and supported tumor cell proliferation under acidic condition. Thus, our study provides evidence that tumor cells display phenotypic plasticity that allows them to survive acid stress.

Curbing Lipids: Impacts ON Cancer and Viral Infection

Lipids play a fundamental role in maintaining normal function in healthy cells. Their functions include signaling, storing energy, and acting as the central structural component of cell membranes. Alteration of lipid metabolism is a prominent feature of cancer, as cancer cells must modify their metabolism to fulfill the demands of their accelerated proliferation rate. This aberrant lipid metabolism can affect cellular processes such as cell growth, survival, and migration. Besides the gene mutations, environmental factors, and inheritance, several infectious pathogens are also linked with human cancers worldwide. Tumor viruses are top on the list of infectious pathogens to cause human cancers. These viruses insert their own DNA (or RNA) into that of the host cell and affect host cellular processes such as cell growth, survival, and migration. Several of these cancer-causing viruses are reported to be reprogramming host cell lipid metabolism. The reliance of cancer cells and viruses on lipid metabolism suggests enzymes that can be used as therapeutic targets to exploit the addiction of infected diseased cells on lipids and abrogate tumor growth. This review focuses on normal lipid metabolism, lipid metabolic pathways and their reprogramming in human cancers and viral infection linked cancers and the potential anticancer drugs that target specific lipid metabolic enzymes. Here, we discuss statins and fibrates as drugs to intervene in disordered lipid pathways in cancer cells. Further insight into the dysregulated pathways in lipid metabolism can help create more effective anticancer therapies.

Breviscapine (BVP) inhibits prostate cancer progression through damaging DNA by minichromosome maintenance protein-7 (MCM-7) modulation

Naturally occurring compounds are reported as effective candidates for prevention and treatment of various cancers. Breviscapine (BVP) is a mixture of flavonoid glycosides, derived from the Chinese herbs. Previous researches have indicated that BVP has comprehensive pharmacological functions. However, little is known about whether BVP has preventive effects on human prostate cancer. Here, we attempted to explore if BVP inhibits human prostate cancer in vitro and in vivo in a comprehensive manner. We found that BVP triggered cytotoxicity in prostate cancer cell lines dose-dependently. BVP-induced DNA damage caused the cell cycle arrest and apoptosis and further induced cell death. High expression of MCM-7 was reduced in BVP-treated cancer cells and tumor tissues, and also the DNA damage response marker of γH2AX is down-regulated by BVP, associated with MCM-7 expression through regulating retinoblastoma protein (Rb) and checkpoint control proteins expression. Additionally, BVP induced apoptotic response in prostate cancer cells and tumors via activating Caspase-3 and PARP. In vivo studies indicated that BVP impeded tumor growth in xenograft animal models. In conclusion, our data indicates that breviscapine (BVP) can be further explored for its potential, which might be used in human prostate cancer therapeutics.