PD-L1 Downregulation and DNA Methylation Inhibition for Molecular Therapy against Cancer Stem Cells in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a heterogeneous cancer characterized by various cellular subtypes. This study investigates the potential of a combination strategy using immunotherapy and epigenetic reprogramming against HCC. We used a transgenic HCC mouse C57BL/6J-TG(ALB1HBV)44BRI/J to assess the dynamics of the programmed death receptor and its ligand (PD-1/PD-L1) and DNA methylation markers. In parallel, PD-L1 RNA silencing was performed in various human HCC cell lines, while combination therapy was performed in a co-culture system using long-term exposure of 5-Azacytidine (5-AZA) and an anti-PD-L1. Data from the mouse model showed that the expressions of Pdcd1, Pdcd1l1, and DNA methyltransferase 1 (Dnmt1) were significantly higher in HCC as compared to the wild-type mice (p < 0.01), supported by the high presence of PD-L1 methylated DNA. In HCC cell lines, PD-L1 silencing was accompanied by DNMT1 reduction, mostly noted in aggressive HCC cell lines, followed by the dysregulation of the cancer stem cell marker EpCAM. In combination therapy, the growth of HCC cells and lymphocytes was limited by the PD-L1 antibody, further reduced in the presence of 5-AZA by up to 20% (p < 0.001). The data demonstrated that combination therapy might be an option as a potential treatment for heterogeneous HCC.

Obeticholic acid and INT-767 modulate collagen deposition in a NASH in vitro model.

Pharmacological treatments for non-alcoholic steatohepatitis (NASH) are still unsatisfactory. Fibrosis is the most significant predictor of mortality and many anti-fibrotic agents are under evaluation. Herein, we assessed in vitro the effects of the FXR agonist obeticholic acid (OCA) and the dual FXR/TGR5 agonist INT-767 in a well-established co-culture NASH model. Co-cultures of human hepatoma and hepatic stellate (HSCs) cells were exposed to free fatty acids (FFAs) alone or in combination with OCA or INT-767. mRNA expression of HSCs activation markers and FXR engagement were evaluated at 24, 96 and 144 hours. Collagen deposition and metalloproteinase 2 and 9 (MMP2-9) activity were compared to tropifexor and selonsertib. FFAs induced collagen deposition and MMP2-9 activity reduction. Co-treatment with OCA or INT-767 did not affect ACTA2 and COL1A1 expression, but significantly reduced FXR and induced SHP expression, as expected. OCA induced a dose-dependent reduction of collagen and induced MMP2-9 activity. Similarly, INT-767 induced collagen reduction at 96 h and a slight increase in MMP2-9. Tropifexor and Selonsertib were also effective in collagen reduction but showed no modulation of MMP2-9. All tested compounds reduced collagen deposition. OCA exerted a more potent and long-lasting effect, mainly related to modulation of collagen turn-over and MMP2-9 activity.

Silybin Modulates Collagen Turnover in an In Vitro Model of NASH.

Silybin has been proposed as a treatment for nonalcoholic steatohepatitis (NASH). In this study, we assessed the effect of Silybin in a well-established in vitro coculture model of early-stage NASH. LX2 and Huh7 cells were exposed to free fatty acid (FFA) and Silybin as mono- or coculture (SCC). Cell viability, LX2 activation, collagen deposition, metalloproteinase 2 and 9 (MMP2-9) activity, and ROS generation were determined at 24, 96, and 144 h. Exposure to FFA induced the activation of LX2 as shown by the increase in cell viability and upregulation of collagen biosynthesis. Interestingly, while cotreatment with Silybin did not affect collagen production in LX2, a significant reduction was observed in SCC. MMP2-9 activity was reduced in FFA-treated Huh7 and SCC and cotreatment with Silybin induced a dose-dependent increase, while no effect was observed in LX2. Silybin also showed antioxidant properties by reducing the FFA-induced production of ROS in all the cell systems. Based on these data, Silybin exerts its beneficial effects by reducing LX2 proliferation and ROS generation. Moreover, MMP2-9 modulation in hepatocytes represents the driving mechanism for the net reduction of collagen in this NASH in vitro model, highlighting the importance of hepatic cells interplay in NASH development and resolution.

Hyaluronic acid inhibition by 4-methylumbelliferone reduces the expression of cancer stem cells markers during hepatocarcinogenesis.

Hyaluronic acid (HA) is a glycosaminoglycan of extracellular matrix related to cell surface which interacts with various cell types. To understand the role of HA during hepatocarcinogenesis, we assessed the effect of the inhibition of HA deposition and its association with heterogeneous hepatocellular carcinoma (HCC) cells. In this study, we used transgenic mice C57BL/6J-Tg(Alb1HBV)44Bri/J (HBV-TG) and normal C57BL/6 J (WT) for in vivo study, while HCC cells Huh7 and JHH6 as in vitro models. Both models were treated with an HA inhibitor 4-methylumbelliferone (4MU). We observed that 4MU treatments in animal model down-regulated the mRNA expressions of HA-related genes Has3 and Hyal2 only in HBV-TG but not in normal WT. As observed in vivo, in HCC cell lines, the HAS2 mRNA expression was down-regulated in Huh7 while HAS3 in JHH6, both with or without the presence of extrinsic HA. Interestingly, in both models, the expressions of various cancer stem cells (CD44, CD90, CD133, and EpCAM) were also decreased. Further, histological analysis showed that 4MU treatment with dose 25 mg/kg/day reduced fibrosis, inflammation, and steatosis in vivo, in addition to be pro-apoptotic. We concluded that the inhibition of HA reduced the expressions of HA-related genes and stem cells markers in both models, indicating a possible modulation of cells-to-cells and cells-to-matrix interaction.

Activation of hepatic stem cells compartment during hepatocarcinogenesis in a HBsAg HBV-transgenic mouse model.

Chronic infection of Hepatitis B Virus (HBV) is one of the highest risk factors of hepatocellular carcinoma (HCC). The accumulation of HBV surface antigen (HBsAg) into hepatocytes induces inflammation and oxidative stress, impairing their replicative ability and allowing the activation of the hepatic stem cells (SC) compartment. This study aimed to understand the involvement of SC during hepatocarcinogenesis in HBsAg-related liver damage, from early injury until HCC. HBsAg-transgenic (TG) and wild type (WT) mouse were followed at several stages of the liver damage: inflammation, early hepatocytes damage, dysplasia, and HCC. Serum transaminases, liver histology, and diagnostic data were collected. The expressions of SC and cancer stem cells (CSC) markers was analyzed by RT-qPCR, immunohistochemistry and Western blot. Starting from 3 months, TG animals showed a progressive liver damage characterized by transaminases increase. The up-regulations of SCs markers Cd34 and Sca-1 started from the beginning of the inflammatory stage while progressive increase of Krt19 and Sox9 and CSCs markers Epcam and Cd133 from early hepatic injury. The expressions of Cd133, Cd34, and Afp were significantly higher in HCC compared to paired non-HCC tissue, in contrast to Epcam and Krt19. Western blot and IHC confirmed the positivity of Cd34 and Cd133 in small cells subpopulation.

Significance of hepatitis virus infection in the oncogenic initiation of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Chronic infection of hepatitis B virus (HBV) and/or hepatitis C virus (HCV) is a major risk factor in the development of the HCC, independently from excessive alcohol abuse and metabolic disease. Since the biology of HBV and HCV is different, their oncogenic effect may go through different mechanisms, direct and/or indirect. Viral hepatitis infection is associated with cellular inflammation, oxidative stress, and DNA damage, that may lead to subsequent hepatic injuries such as chronic hepatitis, fibrosis, cirrhosis, and finally HCC. Direct oncogenic properties of these viruses are related with their genotypic characteristics and the ability of viral proteins to interact with host proteins, thus altering the molecular pathways balance of the cells. In addition, the integration of HBV DNA, especially the gene S and X, in a particular site of the host genome can disrupt chromosomal stability and may activate various oncogenic mechanisms, including those in hematopoietic cells. Recently, several studies also had demonstrated that viral hepatitis could trigger the population of hepatic cancer stem cells. This review summarize available pre-clinical and clinical data in literature regarding oncogenic properties of HBV and HCV in the early initiation of HCC.

The multiple origin of cancer stem cells in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) accounts for approximately 6% of all new cancer cases diagnosed, and due to its aggressiveness, it is the second most common cause of cancer mortality worldwide. Based on different etiological factors, genetic backgrounds, and longtime development of the disease, HCC is characterized by a high phenotypic and functional heterogeneity. Tumor variability occurs both among patients (intertumoral heterogeneity) and within a single tumor (intratumoral heterogeneity). The intratumoral heterogeneity, in particular the variability of the markers of cancer stem cells (CSC) population may determine specific behavior and prognosis of the tumor. Understanding the cellular mechanisms originating CSC will provide an important hint in the management of HCC. The characterization of the cells of origin of cancer can have significant implication in early diagnosis, in the development of appropriate therapies and in the prevention of relapse. Here, we review recent evidences on the possible cellular origin of CSC that play a role in the heterogeneity of the HCC.

Multidrug resistance in hepatic cancer stem cells: the emerging role of miRNAs.

There is a fast growing body of evidence that shows several miRNAs are essential to the key features of cancer stem cells (CSC) in hepatocellular carcinoma. However, the function of the miRNAs in different hepatic CSCs and their role in multidrug resistance mechanisms, in particular in those related to the CSC marker ABCG2, is still poorly understood. This limitation is mainly due to the heterogeneity of hepatocellular carcinoma tissues, different CSC markers and high number of deregulated miRNAs, both in primary tumor sites as well as in the circulation. The identification of CSC-related miRNAs and the modulation of hepatocellular carcinoma multidrug resistance would provide a systemic approach in the management of the disease.

The role of multipotent cancer associated fibroblasts in hepatocarcinogenesis.

BACKGROUND: The presence of tumor supporting cells in various cancer, including in hepatocellular carcinoma (HCC), has become an important target in the study of carcinogenesis. The cancer-associated fibroblast (CAF), one of the most important cellular components in the cancer stroma, might contribute to the progression of the disease due to its plasticity, a behavior of the stem cells. In this study, we investigate the significance of the CAF and its role in the HCC progression and metastasis. METHODS: Primary CAF and non-tumoral fibroblast (NTF) from nine paired HCC and distant non-tumoral liver tissues were isolated and cultured. The cells were characterized by flow cytometry, RT-PCR, anchorage-independent assay and in vitro cells directed trans-differentiation. Co-culture study was performed in Transwell system and xenograft assay was performed in immunodeficient mice. RESULTS: CAF and NTF were positive for CD90, CD44, αSMA, and vimentin and negative for CD34, CD45, CD117, and CD133. When stimulated, they showed the potential to differentiate into adipocytes, osteoblasts, and pancreatic cells. When co-cultured with human HCC cell lines, CAF up-regulated gene expressions of TGFB1 and FAP of HuH-7 and JHH-6 while NTF did not induced either of the genes. Xenograft assay showed that the CAF had the capacity to enter into circulation as confirmed by RT-PCR and DNA sequencing. CONCLUSION: Our data provides evidence of the plasticity of the CAF and the NTF as stem cells in the process of hepatocarcinogenesis and metastasis. These cells mutually interacts with HCC cells. Their trans-differentiation flexibility may induce a switch from normal to cancerous microenvironment.

Recent insights into hepatic cancer stem cells.

It has been suggested that the development of hepatocellular carcinoma (HCC) is related to the existence of cancer stem cells (CSCs) or tumor-initiating cells. Although CSCs populations may be recognized by use of stem cell markers and/or their functional capacities, their profiles might be diverse, because of the heterogeneity of HCC among individuals. Recent studies indicate that activation of CSCs is related to dysregulation of crucial molecular signaling pathways able to alter the intrinsic properties of normal stem cells. This short review describes the latest evidence of the presence of CSCs, alteration of several developmental and oncogenic pathways, CSC-related microRNAs, and drug resistance in HCC. This information may aid the development of potential novel therapy targeting CSCs in HCC.

The expression of CD90/Thy-1 in hepatocellular carcinoma: an in vivo and in vitro study.

Although the CD90 (Thy-1) was proposed as biomarker of several tumors and cancer stem cells, the involvement of this molecule in the progression of hepatocellular carcinoma (HCC) and other less frequent hepatic neoplasms is still undefined. The distribution of CD90 was investigated both in in vivo (human tissues samples) and in vitro (human HCC cell line JHH-6). A total of 67 liver tumors were analyzed: 51 HCC, 6 cholangiocarcinoma and 10 hepatoblastoma. In all cases, paired tissue sample of both the tumor and cirrhotic liver was available. Hepatic tissue obtained in 12 healthy livers was used as control. CD90 gene expression was studied by RT-qPCR, protein expression was assessed by quantitative Western Blot, immunofluorescence and flow cytometry. The CD90 expression analysis showed a significant increment in tumor compared to both its paired cirrhotic tissue and normal liver (p<0.05 and p<0.001, respectively). This increase was accompanied by the up-regulation of stromal component in the cancer, as demonstrated by alpha smooth muscle actin staining. In vitro analysis of JHH-6 cell line showed a higher proliferation capacity of CD90(+) compared to CD90(-) cells (p<0.001), also noticed in 3D clonogenic assay (p<0.05), associated by a significant higher expression of the promoting factors (hepatocyte growth factor, fibroblast associated protein and alpha smooth muscle actin 2). A higher expression of the breast cancer resistance protein was found in CD90(+) subpopulation while the multidrug resistance protein 1 showed an opposite behavior. Collectively, these results point to the importance of CD90 in the HCC.

Gene and functional up-regulation of the BCRP/ABCG2 transporter in hepatocellular carcinoma.

BACKGROUND: The Breast Cancer Resistance Protein (BCRP/ABCG2) is one member of ABC transporters proteins super family responsible of drug resistance. Since data on ABCG2 expression in liver malignances are scanty, here we report the expression of ABCG2 in adult human hepatocellular carcinoma (HCC) in both in vivo and in vitro models with different degree of malignancy. METHODS: In cell lines derived from human hepatocellular carcinoma, ABCG2 gene expression was assessed by reverse transcription quantitative real time PCR and function by Hoechst 33342 efflux assay; protein content was assessed by SDS-PAGE Western blot. RESULTS: ABCG2 expression was found to be highest in the most undifferentiated cell lines, and this was related with a higher functional activity. ABCG2 expression was sensitive to antineoplastic drugs since exposure to 5 µM doxorubicin for 24 hours resulted in significant up-regulations of ABCG2 in all cell lines, particularly in those lines with low basal ABCG2 expression (p<0.01). The gene expression was also investigated in 51 adult liver tissues with HCC and related cirrhosis; normal liver tissue was used as control. ABCG2 gene expression was higher in HCC than both cirrhotic paired tissue and normal tissue. This up-regulation was greater (p<0.05) in pathological poorly differentiated grade G3/G4 than in well-differentiated G1/G2 HCC. CONCLUSIONS: Our results suggest a correlation of ABCG2 gene expression and differentiation stage both in human and HCC derived cell lines. The rapid up-regulation of ABCG2 to exposure to doxorubicin emphasizes the importance of this transporter in accounting for drug resistance in liver tumors.