Hepatitis B doubly spliced protein (HBDSP) promotes hepatocellular carcinoma cell apoptosis via ETS1/GATA2/YY1-mediated p53 transcription

IMPORTANCE

Hepatitis B virus (HBV) spliced variants are associated with viral persistence or pathogenicity. Hepatitis B doubly spliced protein (HBDSP), which has been previously reported as a pleiotropic transactivator protein, can potentially serve as an HBV virulence factor. However, the underlying mechanisms of HBDSP in HBV-associated liver diseases remain to be elucidated. In this study, we revealed that HBDSP promotes cellular apoptosis and induces wt-p53-dependent apoptotic signaling pathway in wt-p53 hepatocellular cells by transactivating p53 transcription, and increases the release of HBV progeny. Therefore, HBDSP may promote the HBV particles release through wt-p53-dependent hepatocellular apoptosis. Our findings suggest that blocking HBDSP-induced wt-p53-dependent apoptosis might have therapeutic values for chronic hepatitis B.

miR-181c regulates MCL1 and cell survival in GATA2 deficient cells

GATA2 is a transcription factor critical for hematopoiesis. Germline mutations in GATA binding protein 2 (GATA2) led to haploinsufficiency, severe cytopenias of multiple cell lineages, susceptibility to infections and strong propensity to develop myelodysplastic syndrome, and acute myeloid leukemia. Mechanisms of progressive cytopenias remain unclear. MicroRNA (miRNA) represents a unique mechanism of post-transcriptional gene regulation. In this study, miRNA profiles were evaluated and eight miRNAs were found to be differentially expressed (≥2-fold, P ≤ 0.05) in patient-derived cell lines (N = 13) in comparison to controls (N = 10). miR-9, miR-181a-2-3p, miR-181c, miR-181c-3p, miR-486-3p, and miR-582 showed increased expression, whereas miR-223 and miR-424-3p showed decreased expression. Cell death assays indicated that miR-181c potently induces cell death in lymphoid (Ly-8 and SP-53) and myeloid (HL-60) cell lines. miR-181c was predicted to target myeloid cell leukemia (MCL)1, which was confirmed by transfection assays, resulting in significantly reduced MCL1 mRNA and decreased live cell numbers. Bone marrow analysis of 34 GATA2 patients showed significantly decreased cellularity, CD34-positive cells, monocytes, dendritic cells, NK cells, B cells, and B cell precursors in comparison to healthy controls (N = 29; P < 0.001 for each), which was accompanied by decreased levels of MCL1 (P < 0.05). GATA2 expression led to significant repression of miR-181c expression in transfection experiments. Conversely, knockdown of GATA2 led to increased miR-181c expression. These findings indicate that miR-181c expression is increased and MCL1 levels decreased in GATA2 deficiency cells, and that GATA2 represses miR-181c transcription. Increased miR-181c may contribute to elevated cell death and cytopenia in GATA2 deficiency potentially through down-regulation of MCL1.

DNA Methylation as a Potential Molecular Mechanism in X-linked Dystonia-Parkinsonism

BACKGROUND

X-linked dystonia-parkinsonism is a neurodegenerative movement disorder. The underlying molecular basis has still not been completely elucidated, but likely involves dysregulation of TAF1 expression. In X-linked dystonia-parkinsonism, 3 disease-specific single-nucleotide changes (DSCs) introduce (DSC12) or abolish (DSC2 and DSC3) CpG dinucleotides and consequently sites of putative DNA methylation. Because transcriptional regulation tightly correlates with specific epigenetic marks, we investigated the role of DNA methylation in the pathogenesis of X-linked dystonia-parkinsonism.

METHODS

DNA methylation at DSC12, DSC3, and DSC2 was quantified by bisulfite pyrosequencing in DNA from peripheral blood leukocytes, fibroblasts, induced pluripotent stem cell-derived cortical neurons and brain tissue from X-linked dystonia-parkinsonism patients and age- and sex-matched healthy Filipino controls in a prospective study.

RESULTS

Compared with controls, X-linked dystonia-parkinsonism patients showed striking differences in DNA methylation at the 3 investigated CpG sites. Using methylation-sensitive luciferase reporter gene assays and immunoprecipitation, we demonstrated (1) that lack of DNA methylation because of DSC2 and DSC3 affects gene promoter activity and (2) that methylation at all 3 investigated CpG sites alters DNA-protein interaction. Interestingly, DSC3 decreased promoter activity per se compared with wild type, and promoter activity further decreased when methylation was present. Moreover, we identified specific binding of proteins to the investigated DSCs that are associated with splicing and RNA and DNA binding.

CONCLUSIONS

We identified altered DNA methylation in X-linked dystonia-parkinsonism patients as a possible additional mechanism modulating TAF1 expression and putative novel targets for future therapies using DNA methylation-modifying agents. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The Blockage of KCa3.1 Channel Inhibited Proliferation, Migration and Promoted Apoptosis of Human Hepatocellular Carcinoma Cells

The intermediate conductance calcium-activated potassium channel KCa3.1 plays an important role in regulating cell proliferation and migration. However, the role of KCa3.1 channel in human hepatocellular carcinoma remained unknown. This study was therefore performed to investigate the effects of KCa3.1 potassium channel blocker on the proliferation, apoptosis and migration of human hepatocellular cancer cells HepG2. KCa3.1 mRNA and protein were detected in HepG2. Furthermore, KCa3.1 potassium channel blocker TRAM-34 was capable to inhibit the proliferation and induce the apoptosis of HepG2 cells, which can be partially attenuated by 1-EBIO, an activator of KCa3.1 channel. Moreover, the migration of HepG2 was obviously inhibited by TRAM-34. Consistently, knockdown of KCa3.1 channel using its siRNA was also able to induce apoptosis and suppress proliferation and migration of HepG2. Meanwhile, intracellular ROS level was found augmented in HepG2 treated with TRAM-34. More importantly, p53 protein was found translocation from the cytoplasm into the nuclei of HepG2. Collectively, inhibition of KCa3.1 channel suppressed the growth and migration, and promoted the apoptosis of human hepatocellular carcinoma cells by regulating intracellular ROS level and promoting p53 activation. This data suggests TRAM-34 as a promising anti-tumor drug for liver cancer.

A3 adenosine receptor mediates apoptosis in in vitro RCC4-VHL human renal cancer cells by up-regulating AMID expression

PURPOSE

Accumulating studies have shown that extracellular adenosine induces apoptosis in various cancer cells via diverse signaling pathways. We sought to understand adenosine induced apoptosis in human renal cancer cells and the underlying pathway.

MATERIALS AND METHODS

RCC4-VHL (European Collection of Animal Cell Cultures, Salisbury, United Kingdom), ACHN (Cell Resource Center for Biomedical Research, Institute of Development, Aging and Cancer, Tohuku University, Aoba-ku, Sendai, Japan) and 786-O (ATCC®) human renal cancer cells were cultured. MTT assay, TUNEL staining, reverse transcriptase-polymerase chain reaction and Western blot were done in cells untransfected and transfected with siRNA silencing the A(3) adenosine receptor targeted gene or the AMID targeted gene.

RESULTS

Adenosine induced apoptosis in all cell types used in a concentration (1 to 10 mM) dependent manner. A similar effect was obtained with the A(3) adenosine receptor agonist 2-Cl-IB-MECA. Adenosine induced RCC4-VHL cell death was inhibited by the A(3) adenosine receptor inhibitor MRS1191 or by knocking down A(3) adenosine receptor or AMID. Adenosine up-regulated the expression of AMID mRNA and protein in RCC4-VHL cells, which was suppressed by A(3) adenosine receptor knockdown. Moreover, adenosine promoted AMID translocation from cytosol to nucleus.

CONCLUSIONS

Adenosine induces RCC4-VHL cell apoptosis by up-regulating AMID expression and accumulating AMID in the nucleus via A(3) adenosine receptor.