Homeobox protein VentX induces p53-independent apoptosis in cancer cells

EZH2 deregulates BMP, Hedgehog, and Hippo cell signaling pathways in esophageal squamous cell carcinoma

PURPOSE

Cell signaling pathways play central roles in cellular stemness state, and aberrant activation of these cascades is attributed to the severity of esophageal squamous cell carcinoma (ESCC). In this study, we aimed to determine the potential impact of enhancer of zeste homolog 2 (EZH2) gene on different cell signaling pathways including bone morphogenesis protein (BMP), Hedgehog, and Hippo in ESCC, and to illuminate EZH2-mediated gene regulatory networks in this aggressive malignancy.

MATERIALS AND METHODS

EZH2 silencing was performed in two ESCC lines, KYSE-30 and YM-1, followed by gene expression analysis of BMP, Hedgehog, and Hippo signaling using RT-qPCR. EZH2 enforced expression was induced in both cell lines and gene expression of the pathways was evaluated in parallel. The contribution of EZH2 in epithelial-mesenchymal transition (EMT) and cell migration were also evaluated.

RESULTS

EZH2 downregulation decreased expression of the vital components of the Hedgehog and Hippo signaling, while EZH2 upregulation significantly increased its levels in both ESCC cell lines. The expression of BMP target genes was either reduced in EZH2-expressing cells or increased in EZH2-silencing cells. Enforced expression of EZH2 stimulated downregulation of epithelial markers and upregulation of mesenchymal markers in KYSE-30 and YM-1 ​cells. Significant downregulation of mesenchymal markers was detected following the silencing of EZH2 in the cells. Knocking down EZH2 decreased migration, while enforced expression of EZH2 increased migration in both ESCC lines.

CONCLUSIONS

These results may support the promoting role of EZH2 in ESCC tumorigenesis through the recruitment of important cell signaling pathways.

Ventx Family and Its Functional Similarities with Nanog: Involvement in Embryonic Development and Cancer Progression

The Ventx family is one of the subfamilies of the ANTP (antennapedia) superfamily and belongs to the NK-like (NKL) subclass. Ventx is a homeobox transcription factor and has a DNA-interacting domain that is evolutionarily conserved throughout vertebrates. It has been extensively studied in Xenopus, zebrafish, and humans. The Ventx family contains transcriptional repressors widely involved in embryonic development and tumorigenesis in vertebrates. Several studies have documented that the Ventx family inhibited dorsal mesodermal formation, neural induction, and head formation in Xenopus and zebrafish. Moreover, Ventx2.2 showed functional similarities to Nanog and Barx1, leading to pluripotency and neural-crest migration in vertebrates. Among them, Ventx protein is an orthologue of the Ventx family in humans. Studies have demonstrated that human Ventx was strongly associated with myeloid-cell differentiation and acute myeloid leukemia. The therapeutic potential of Ventx family inhibition in combating cancer progression in humans is discussed. Additionally, we briefly discuss genome evolution, gene duplication, pseudo-allotetraploidy, and the homeobox family in Xenopus.

Intellectual disability: dendritic anomalies and emerging genetic perspectives

Intellectual disability (ID) corresponds to several neurodevelopmental disorders of heterogeneous origin in which cognitive deficits are commonly associated with abnormalities of dendrites and dendritic spines. These histological changes in the brain serve as a proxy for underlying deficits in neuronal network connectivity, mostly a result of genetic factors. Historically, chromosomal abnormalities have been reported by conventional karyotyping, targeted fluorescence in situ hybridization (FISH), and chromosomal microarray analysis. More recently, cytogenomic mapping, whole-exome sequencing, and bioinformatic mining have led to the identification of novel candidate genes, including genes involved in neuritogenesis, dendrite maintenance, and synaptic plasticity. Greater understanding of the roles of these putative ID genes and their functional interactions might boost investigations into determining the plausible link between cellular and behavioral alterations as well as the mechanisms contributing to the cognitive impairment observed in ID. Genetic data combined with histological abnormalities, clinical presentation, and transgenic animal models provide support for the primacy of dysregulation in dendrite structure and function as the basis for the cognitive deficits observed in ID. In this review, we highlight the importance of dendrite pathophysiology in the etiologies of four prototypical ID syndromes, namely Down Syndrome (DS), Rett Syndrome (RTT), Digeorge Syndrome (DGS) and Fragile X Syndrome (FXS). Clinical characteristics of ID have also been reported in individuals with deletions in the long arm of chromosome 10 (the q26.2/q26.3), a region containing the gene for the collapsin response mediator protein 3 (CRMP3), also known as dihydropyrimidinase-related protein-4 (DRP-4, DPYSL4), which is involved in dendritogenesis. Following a discussion of clinical and genetic findings in these syndromes and their preclinical animal models, we lionize CRMP3/DPYSL4 as a novel candidate gene for ID that may be ripe for therapeutic intervention.

Correlation between SALL4 stemness marker and bone morphogenetic protein signaling genes in esophageal squamous cell carcinoma

SALL4, as a stemness marker, plays a key role in the maintenance of pluripotency and self-renewal of cancer stem cells. To elucidate probable linkage between SALL4 stemness marker and bone morphogenetic protein (BMP) cell signaling pathway, we aimed to analyze the expression levels of the related genes in esophageal squamous cell carcinoma (ESCC) patients. Tumoral and corresponding margin normal tissues from 50 treatment-naive ESCC patients were subjected for expression analysis using relative comparative real-time reverse transcription polymerase chain reaction. There were significant correlations between SALL4 mRNA and BMP signaling target genes expression including SIZN1, VENTX, and DIDO1 (P < 0.01). Tight associations of gene expression were observed in primary stages of tumor progression (stages I/II), and the invaded tumors to the adventitia (T3/T4). Furthermore, significant correlations between the expression of BMP signaling target genes were observed (P < 0.01). SALL4 may play role in tumorigenesis and tumor cell invasiveness of ESCC through correlation with BMP signaling genes.

The homeobox protein VentX reverts immune suppression in the tumor microenvironment

Immune suppression in the tumor microenvironment (TME) is a central obstacle to effective immunotherapy. Tumor-associated macrophages (TAMs) are key components of the TME. Although TAMs have been viewed as an ideal target of intervention to steer immunity in cancer treatment, the approach has been hampered by the lack of knowledge of how TAM plasticity is controlled by cell intrinsic factors. VentX is a homeobox protein implicated in proliferation and differentiation of human hematopoietic and immune cells. Using clinical samples obtained from cancer patients, we find that VentX expression is drastically reduced in TAMs. We show here that VentX promotes M1 differentiation of TAMs, and that VentX-regulated TAMs, in turn, revert immune suppression at the TME. Using a NSG mouse model of human colon cancers, we demonstrate that VentX regulates TAM function in tumorigenesis in vivo. Our findings suggest a mechanism underlying immune suppression at TME and potential applications of VentX-regulated TAMs in cancer immunotherapy.

Tumour associated macrophages (TAMs) polarize into either pro-tumor or anti-tumor phenotypes. Here the authors show that the homeobox protein VentX is downregulated in clinical samples of colorectal cancer and regulates TAMs plasticity with its forced re-expression converting TAMs into an anti-tumor phenotype.

VENTX induces expansion of primitive erythroid cells and contributes to the development of acute myeloid leukemia in mice

Homeobox genes are key regulators in normal and malignant hematopoiesis. The human Vent-like homeobox gene VENTX, a putative homolog of the Xenopus laevis Xvent-2 gene, was shown to be highly expressed in normal myeloid cells and in patients with acute myeloid leukemia. We now demonstrate that constitutive expression of VENTX suppresses expression of genes responsible for terminal erythroid differentiation in normal CD34⁺ stem and progenitor cells. Transplantation of bone marrow progenitor cells retrovirally engineered to express VENTX caused massive expansion of primitive erythroid cells and partly acute erythroleukemia in transplanted mice. The leukemogenic potential of VENTX was confirmed in the AML1-ETO transplantation model, as in contrast to AML1-ETO alone co-expression of AML1-ETO and VENTX induced acute myeloid leukemia, partly expressing erythroid markers, in all transplanted mice. VENTX was highly expressed in patients with primary human erythroleukemias and knockdown of VENTX in the erythroleukemic HEL cell line significantly blocked cell growth. In summary, these data indicate that VENTX is able to perturb erythroid differentiation and to contribute to myeloid leukemogenesis when co-expressed with appropriate AML oncogenes and point to its potential significance as a novel therapeutic target in AML.

Xom induces proteolysis of β-catenin through GSK3β-mediated pathway

The dorsal cell fate determination factor β-catenin and its antagonist, the ventral cell fate determination factor Xom, are expressed and distributed in a polarized fashion during early vertebrate embryogenesis. Ubiquitin-mediated proteolysis has been shown to control the abundance of both β-catenin and Xom. However, the mechanism of ubiquitin-mediated proteolysis in regulating dorsoventral patterning remains largely unclear. Our current study shows that Xom induces proteolysis of β-catenin through GSK3-mediated phosphorylation of Ser33/37 of β-catenin. Our findings reveal a novel pathway that regulates β-catenin stability, and suggest, for the first time, a critical function of ubiquitin-mediated proteolysis in balancing the integration of dorsal-ventral signals and the polarized distribution of β-catenin and Xom during dorsoventral axis formation.

Histone acetyltransferase p300/CBP inhibitor C646 blocks the survival and invasion pathways of gastric cancer cell lines

The histone acetyltransferases (HATs) adenovirus E1A-associated protein (p300) and CREB binding protein (CBP) serve as coactivators during a diverse assortment of cellular processes. In the present study, p300 and CBP were highly expressed in 5 gastric cancer (GC) cell lines (SGC‑7901, MKN45, MGC-803, BGC-823 and KATO III) compared with human normal gastric epithelial cell line (GES-1). C646, a selective inhibitor of p300 and CBP, inhibited cell viability and cell cycle and promoted cell apoptosis in all 5 GC cell lines. In addition, C646 suppressed the migration and invasion capability of the GC cell lines, except for the middle-differentiated SGC-7901 cell line. Furthermore, we detected the differential expression of corresponding oncogenic signalling molecules, such as c-Met, Akt, Bcl-2, Bax, cyclin D1, MMP7 and MMP9, in GC cells following C646 treatment. In conclusion, our results suggest that C646 inhibits the acetylation of histone H3 via inactivation of p300 and CBP, resulting in antineoplastic effects toward GC cells. Thus, the selective HAT inhibitor C646 could be a promising antitumour reagent for GC treatment.