Hepatitis C virus-induced cancer stem cell-like signatures in cell culture and murine tumor xenografts.
ABSTRACT Hepatitis C virus (HCV) infection is a prominent risk factor for the development of hepatocellular carcinoma (HCC). Similar to most solid tumors, HCCs are believed to contain poorly differentiated cancer stem cell-like cells (CSCs) that initiate tumorigenesis and confer resistance to chemotherapy. In these studies, we demonstrate that the expression of an HCV subgenomic replicon in cultured cells results in the acquisition of CSC traits. These traits include enhanced expression of doublecortin and CaM kinase-like-1 (DCAMKL-1), Lgr5, CD133, α-fetoprotein, cytokeratin-19 (CK19), Lin28, and c-Myc. Conversely, curing of the replicon from these cells results in diminished expression of these factors. The putative stem cell marker DCAMKL-1 is also elevated in response to the overexpression of a cassette of pluripotency factors. The DCAMKL-1-positive cells isolated from hepatoma cell lines by fluorescence-activated cell sorting (FACS) form spheroids in Matrigel. The HCV RNA abundance and NS5B levels are significantly reduced by the small interfering RNA (siRNA)-led depletion of DCAMKL-1. We further demonstrate that HCV replicon-expressing cells initiate distinct tumor phenotypes compared to the tumors initiated by parent cells lacking the replicon. This HCV-induced phenotype is characterized by high-level expression/coexpression of DCAMKL-1, CK19, α-fetoprotein, and active c-Src. The results obtained by the analysis of liver tissues from HCV-positive patients and liver tissue microarrays reiterate these observations. In conclusion, chronic HCV infection appears to predispose cells toward the path of acquiring cancer stem cell-like traits by inducing DCAMKL-1 and hepatic progenitor and stem cell-related factors. DCAMKL-1 also represents a novel cellular target for combating HCV-induced hepatocarcinogenesis.
Article: Side-population cells in luminal-type breast cancer have tumour-initiating cell properties, and are regulated by HER2 expression and signalling.[show abstract] [hide abstract]
ABSTRACT: The expression of side-population (SP) cells and their relation to tumour-initiating cells (T-ICs) have been insufficiently studied in breast cancer (BC). We therefore evaluated primary cell cultures derived from patients and a panel of human BC cell lines with luminal- or basal-molecular signatures for the presence of SP and BC stem cell markers. The SPs from luminal-type BC were analysed for BC T-IC characteristics, including human epidermal growth factor receptor 2 (HER2), ERalpha, IGFBP7 expression and their ability to initiate tumours in non-obese diabetic severe combined immunodeficiency (NOD/SCID) mice. Pharmacological modulators were used to assess the effects of HER2 signalling and breast cancer-resistance protein (BCRP) expression on SPs. The SP was more prevalent in the luminal subtype of BC compared with the basal subtype. HER2 expression was significantly correlated with the occurrence of an SP (r(2)=0.75, P=0.0003). Disappearance of SP in the presence of Ko143, a specific inhibitor of the ATP-binding cassette transporter BCRP, suggests that BCRP is the predominant transporter expressed in this population. The SP also decreased in the presence of HER2 signalling inhibitors AG825 or trastuzumab, strengthening the notion that HER2 contributed to the SP phenotype, likely through downstream AKT signalling. The SP cells from luminal-type MCF-7 cells with enforced expression of HER2, and primary cells with luminal-like properties from a BC patient, displayed enrichment in cells capable of repopulating tumours in NOD/SCID mice. Engraftment of SP cells was inhibited by pretreatment with AG825 or by in vivo treatment with trastuzumab. Our findings indicate an important role of HER2 in regulating SP and hence T-ICs in BC, which may account for the poor responsiveness of HER2-positive BCs to chemotherapy, as well as their aggressiveness.British Journal of Cancer 02/2010; 102(5):815-26. · 5.04 Impact Factor
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ABSTRACT: Human livers contain two pluripotent progenitors: hepatic stem cells and hepatoblasts. The hepatic stem cells uniquely express the combination of epithelial cell adhesion molecule (EpCAM), neural cell adhesion molecule (NCAM), cytokeratin (CK) 19, albumin +/-, and are negative for alpha-fetoprotein (AFP). They are precursors to hepatoblasts, which differ from hepatic stem cells in size, morphology, and in expressing the combination of EpCAM, intercellular cell adhesion molecule (ICAM-1), CK19, albumin++, and AFP++. The hepatic stem cells are located in vivo in stem cell niches: the ductal plates in fetal and neonatal livers and canals of Hering in pediatric and adult livers. The hepatoblasts are contiguous to the niches, decline in numbers with age, wax and wane in numbers with injury responses, and are proposed to be the liver's transit-amplifying cells. In adult livers, intermediates between hepatic stem cells and hepatoblasts and between hepatoblasts and adult parenchyma are observed. Amplification of one or both pluripotent cell subpopulations can occur in diseases; for example, hepatic stem cell amplification occurs in mild forms of liver failure, and hepatoblast amplification occurs in forms of cirrhosis. Liver is, therefore, similar to other tissues in that regenerative processes in postnatal tissues parallel those occurring in development and involve populations of stem cells and progenitor cells that can be identified by anatomic, antigenic, and biochemical profiles.Hepatology 12/2008; 48(5):1598-607. · 11.66 Impact Factor
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ABSTRACT: Hepatitis C virus (HCV) replication is associated with the endoplasmic reticulum (ER), where the virus causes stress. Cells cope with ER stress by activating an adaptive program called the unfolded protein response (UPR), which alleviates this stress by stimulating protein folding and degradation in the ER and down-regulating overall protein synthesis. Recent work suggests that HCV also alters ER calcium homeostasis, inducing oxidative stress. Future progress in understanding the control that HCV exerts over the ER will provide insight into viral strategies for pathogenesis and persistence in chronically infected patients.Trends in Microbiology 05/2005; 13(4):159-63. · 7.91 Impact Factor