Hepatocellular and cholangiolar carcinoma-derived cell lines reveal distinct sets of chromosomal imbalances

PGV-1 Causes Disarrangement of Spindle Microtubule Organization Resulting in Aberrant Mitosis in HLF and HuH6 Cells Associated with Altered MYCN Status

Purpose

The HLF and HuH-6 cell lines represent hepatocellular carcinoma (HCC) with different characteristics in chromosome content that may give different drug responses. Here, PGV-1 was intended to challenge the growth-suppressing effect on HLF and HuH-6 and trace the molecular target mechanism of action compared to sorafenib.

Methods

We applied MTT cytotoxic assay, colony forming assay, flow cytometry analysis, immunofluorescence assay and western blot assay.

Results

PGV-1 exhibited cytotoxic effects on HLF and HuH-6 with IC-50 values of 1 µM and 2 µM, respectively, whereas sorafenib showed less cytotoxicity with IC-50 values of 5 µM and 8 µM respectively. PGV-1 suppressed the cell growth permanently but not for sorafenib. Sorafenib did not change the cell cycle profiles on both cells, but PGV-1 arrested the cells at G2/M with the characteristic of senescent cells and mitotic disarrangement. PGV-1 and sorafenib showed the same effect in downregulating p-EGFR, indicating that both compounds have the same target on EGFR activation or as Tyrosine kinase inhibitors. PGV-1 suppressed the MYCN expression in HuH-6 and HLF cells but stabilized cMYC-T58 indicating that even though the MYCN was downregulated, the cells maintained the active form of cMYC. In this regard, PGV-1 also stabilized the expression of PLK-1 and AurA.

Conclusion

PGV-1 elicits stronger cytotoxic properties compared to sorafenib. The lower the MYCN expression, the higher the cytotoxic effect of PGV-1. PGV-1 abrogates cell cycle progression of both cells in mitosis through EGFR inhibition and stabilizes PLK-1 and AurA in correlation with the suppression of MYCN expression.

Mechanisms of Sorafenib Resistance in HCC Culture Relate to the Impaired Membrane Expression of Organic Cation Transporter 1 (OCT1)

Introduction

Sorafenib, an FDA-approved drug for advanced hepatocellular carcinoma (HCC) treatment, encounters resistance in many patients. Deciphering the mechanisms underlying sorafenib resistance is crucial for devising alternative strategies to overcome it.

Aim

This study aimed to investigate sorafenib resistance mechanisms using a diverse panel of HCC cell lines.

Methods

HCC cell lines were subjected to continuous sorafenib treatment, and stable cell lines (Huh 7.5 and Huh 7PX) exhibiting sustained growth in its presence were isolated. The investigation of drug resistance mechanisms involved a comparative analysis of drug-targeted signal transduction pathways (EGFR/RAF/MEK/ERK/Cyclin D), sorafenib uptake, and membrane expression of the drug uptake transporter.

Results

HCC cell lines (Huh 7.5 and Huh 7PX) with a higher IC50 (10μM) displayed a more frequent development of sorafenib resistance compared to those with a lower IC50 (2-4.8μM), indicating a potential impact of IC50 variation on initial treatment response. Our findings reveal that activated overexpression of Raf1 kinases and impaired sorafenib uptake, mediated by reduced membrane expression of organic cation transporter-1 (OCT1), contribute to sorafenib resistance in HCC cultures. Stable expression of the drug transporter OCT1 through cDNA transfection or adenoviral delivery of OCT1 mRNA increased sorafenib uptake and successfully overcame sorafenib resistance. Additionally, consistent with sorafenib resistance in HCC cultures, cirrhotic liver-associated human HCC tumors often exhibited impaired membrane expression of OCT1 and OCT3.

Conclusion

Intrinsic differences among HCC cell clones, affecting sorafenib sensitivity at the expression level of Raf kinases, drug uptake, and OCT1 transporters, were identified. This study underscores the potential of HCC tumor targeted OCT1 expression to enhance sorafenib treatment response.

Heterogeneous molecular behavior in liver tumors (HCC and CCA) of two patients with acute intermittent porphyria

INTRODUCTION

Acute intermittent porphyria (AIP) is a very rare (orphan) metabolic disorder of porphyrin biosynthesis which is characterized by elevated plasma and urine levels of 5-aminolevulinic acid (5-ALA) and porphobilinogen (PBG). Patients with this disorder which is caused by a germline mutation of the hydroxymethylbilan-synthase (HMBS)-gene have a high risk of primary liver cancer which may be determined by disease activity. The exact mechanism of carcinogenesis of this rare tumor is unknown, however.

MATERIALS AND METHODS

We analyzed paraffin-embedded formalin-fixed liver tumor and normal liver specimens of two female AIP patients treated at the Munich EPNET center. One patient had developed hepatocellular carcinoma (HCC), the other intrahepatic cholangiocarcinoma (CCA). Since biallelic inactivation of HMBS had been observed in one study, we used Sanger and next-generation sequencing with a 8 gene porphyria panel plus 6 potential modifier loci to search for mutations in DNA extractions.

RESULTS

In the patient with the HCC, we found a second inactivating mutation in the HMBS gene in the tumor but not in the adjacent normal liver tissue. No mutation could be found in the liver tissues of the patient with CCA, however.

CONCLUSIONS

Biallelic inactivation of HMBS or protoporphyrinogen-oxidase (PPOX), another enzyme of porphyrin biosynthesis, has been observed in patients with acute porphyrias and liver tumors. We could confirm this in our patient with HCC with a mutation in HMBS but not in the one with CCA. Since 5-ALA can be converted into carcinogenic substances such as 4,5-dioxovaleric acid (DOVA) or 3,6-dihydropyrazine-2,5-dipropanoic acid (= cyclic dimerization product of 5-ALA), local production of these metabolites in hepatic areas with complete loss of HMBS activity may contribute to liver carcinogenesis.

Generation of new hepatocyte-like in vitro models better resembling human lipid metabolism

In contrast to human hepatocytes in vivo, which solely express acyl-coenzyme A:cholesterol acyltransferase (ACAT) 2, both ACAT1 and ACAT2 (encoded by SOAT1 and SOAT2) are expressed in primary human hepatocytes and in human hepatoma cell lines. Here, we aimed to create hepatocyte-like cells expressing the ACAT2, but not the ACAT1, protein to generate a model that - at least in this regard - resembles the human condition in vivo and to assess the effects on lipid metabolism. Using the Clustered Regularly Interspaced Short Palindromic Repeats technology, we knocked out SOAT1 in HepG2 and Huh7.5 cells. The wild type and SOAT2-only-cells were cultured with fetal bovine or human serum and the effects on lipoprotein and lipid metabolism were studied. In SOAT2-only-HepG2 cells, increased levels of cholesterol, triglycerides, apolipoprotein B and lipoprotein(a) in the cell media were detected; this was likely dependent of the increased expression of key genes involved in lipid metabolism (e.g. MTP, APOB, HMGCR, LDLR, ACACA, and DGAT2). Opposite effects were observed in SOAT2-only-Huh7.5 cells. Our study shows that the expression of SOAT1 in hepatocyte-like cells contributes to the distorted phenotype observed in HepG2 and Huh7.5 cells. As not only parameters of lipoprotein and lipid metabolism but also some markers of differentiation/maturation increase in the SOAT2-only-HepG2 cells cultured with HS, this cellular model represent an improved model for studies of lipid metabolism.

Modulation of the IL-6-Signaling Pathway in Liver Cells by miRNAs Targeting gp130, JAK1, and/or STAT3

Interleukin-6 (IL-6)-type cytokines share the common receptor glycoprotein 130 (gp130), which activates a signaling cascade involving Janus kinases (JAKs) and signal transducer and activator of transcription (STAT) transcription factors. IL-6 and/or its signaling pathway is often deregulated in diseases, such as chronic liver diseases and cancer. Thus, the identification of compounds inhibiting this pathway is of interest for future targeted therapies. We established novel cellular screening systems based on a STAT-responsive reporter gene (Cypridina luciferase). Of a library containing 538 microRNA (miRNA) mimics, several miRNAs affected hyper-IL-6-induced luciferase activities. When focusing on candidate miRNAs specifically targeting 3′ UTRs of signaling molecules of this pathway, we identified, e.g., miR-3677-5p as a novel miRNA affecting protein expression of both STAT3 and JAK1, whereas miR-16-1-3p, miR-4473, and miR-520f-3p reduced gp130 surface expression. Interestingly, combination treatment with 2 or 3 miRNAs targeting gp130 or different signaling molecules of the pathway did not increase the inhibitory effects on phospho-STAT3 levels and STAT3 target gene expression compared to treatment with single mimics. Taken together, we identified a set of miRNAs of potential therapeutic value for cancer and inflammatory diseases, which directly target the expression of molecules within the IL-6-signaling pathway and can dampen inflammatory signal transduction.

Coronaviruses and arteriviruses display striking differences in their cyclophilin A-dependence during replication in cell culture

Cyclophilin A (CypA) is an important host factor in the replication of a variety of RNA viruses. Also the replication of several nidoviruses was reported to depend on CypA, although possibly not to the same extent. These prior studies are difficult to compare, since different nidoviruses, cell lines and experimental set-ups were used. Here, we investigated the CypA dependence of three distantly related nidoviruses that can all replicate in Huh7 cells: the arterivirus equine arteritis virus (EAV), the alphacoronavirus human coronavirus 229E (HCoV-229E), and the betacoronavirus Middle East respiratory syndrome coronavirus (MERS-CoV). The replication of these viruses was compared in the same parental Huh7 cells and in CypA-knockout Huh7 cells generated using CRISPR/Cas9-technology. CypA depletion reduced EAV yields by ~ 3-log, whereas MERS-CoV progeny titers were modestly reduced (3-fold) and HCoV-229E replication was unchanged. This study reveals that the replication of nidoviruses can differ strikingly in its dependence on cellular CypA.

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Nidoviruses display differences in sensitivity towards cyclophilin A depletion.

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Replication of MERS-coronavirus is reduced modestly in cyclophilin A-knockout cells.

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Equine arteritis virus replication is strongly inhibited by cyclophilin A depletion.

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Chromosomal anomalies complicate CRISPR/Cas9-mediated gene editing in Huh7 cells.

Distinct Responses of Cytotoxic Ganoderma lucidum Triterpenoids in Human Carcinoma Cells

The medicinal mushroom Ganoderma lucidum is well recognized for its effective cancer-preventative and therapeutic properties, while specific components responsible for these anticancer effects are not well studied. Six triterpenoids that are ganolucidic acid E, lucidumol A, ganodermanontriol, 7-oxo-ganoderic acid Z, 15-hydroxy-ganoderic acid S, and ganoderic acid DM were isolated and identified from an extract of the mushroom. All compounds reduced cell growth in three human carcinoma cells (Caco-2, HepG2, and HeLa cells) dose dependently with LC50s from 20.87 to 84.36 μM. Moreover, the six compounds induced apoptosis in HeLa cells with a maximum increase (22%) of sub-G1 accumulations and 43.03% apoptotic cells in terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay (15-hydroxy-ganoderic acid S treatment). Apoptosis was further confirmed by annexin-V staining. Four of the compounds also caused apoptosis in Caco-2 cells with maximum 9.5% increase of sub-G1 accumulations (7-oxo-ganoderic acid Z treatment) and maximum 29.84% apoptotic cells in TUNEL assay (ganoderic acid DM treatment). Contrarily, none of the compounds induced apoptosis in HepG2 cells. The different responses of the three cell lines following these treatments indicated that the bioactive properties of these compounds may vary from cells of different sites of origin and are likely acting under diverse regulatory mechanisms.