New advances of DNA methylation in liver fibrosis, with special emphasis on the crosstalk between microRNAs and DNA methylation machinery

AbstractEpigenetics refers to the study of heritable changes in the pattern of gene expression that is controlled by a mechanism specifically not due to changes the primary DNA sequence. Well-known epigenetic mechanisms include DNA methylation, post-translational histone modifications and RNA-based mechanisms including those controlled by small non-coding RNAs (miRNAs). Recent studies have shown that epigenetic modifications orchestrate the hepatic stellate cell (HSC) activation and liver fibrosis. In this review we focus on the aberrant methylation of CpG island promoters of select genes is the prominent epigenetic mechanism to effectively silence gene transcription facilitating HSC activation and liver fibrosis. Furthermore, we also discuss epigenetic dysregulation of tumor-suppressor miRNA genes by promoter DNA methylation and the interaction of DNA methylation with miRNAs involved in the regulation of HSC activation and liver fibrosis. Recent advances in epigenetics alterations in the pathogenesis of liver fibrosis and their possible use as new therapeutic targets and biomarkers

β-arrestin1-mediated acetylation of Gli1 regulates Hedgehog/Gli signaling and modulates self-renewal of SHH medulloblastoma cancer stem cells

Background Aberrant Sonic Hedgehog/Gli (Hh/Gli) signaling pathway is a critical regulator of Sonic hedgehog medulloblastoma (SHH-MB). Cancer stem cells (CSCs), thought to be largely responsible for tumor initiation, maintenance, dissemination and relapse, have been identified in SHH-MB. Since we previously demonstrated that Hh/Gli signaling controls CSCs features in SHH-MB and that in these tumors miR-326 is down regulated, here we investigated whether there is a functional link between Hh/Gli signaling and miR-326. Methods We evaluated β-arrestin1 (Arrb1) and its intragenic miR-326 levels in CSCs derived from SHH-MB. Subsequently, we modulated the expression of Arrb1 and miR-326 in CSCs in order to gain insight into their biological role. We also analyzed the mechanism by which Arrb1 and miR-326 control Hh/Gli signaling and self-renewal, using luciferase and protein immunoprecipitation assays. Results Low levels of Arrb1 and miR-326 represent a feature of CSCs derived from SHH-MB. We observed that re-expression of Arrb1 and miR-326 inhibits Hh/Gli signaling pathway at multiple levels, which cause impaired proliferation and self-renewal, accompanied by down regulation of Nanog levels. In detail, miR-326 negatively regulates two components of the Hh/Gli pathway the receptor Smoothened (Smo) and the transcription factor Gli2, whereas Arrb1 suppresses the transcriptional activity of Gli1, by potentiating its p300-mediated acetylation. Conclusions Our results identify a new molecular mechanism involving miR-326 and Arrb1 as regulators of SHH-MB CSCs. Specifically, low levels of Arrb1 and miR-326 trigger and maintain Hh/Gli signaling and self-renewal

RUNX3 acts as an ocogene through a hedgehog-dependent pathway in selected human neoplasms

Ph.DDOCTOR OF PHILOSOPH

Prognostic significance of the methylation of Wnt pathway antagonists-CXXC4, DACT2, and the inhibitors of sonic hedgehog signaling-ZIC1, ZIC4, and HHIP in head and neck squamous cell carcinomas

Aberrations in Wnt and Shh signaling pathways are related to the pathogenesis of head and neck carcinomas, and their activation frequently results from epigenetic alterations. This study aimed to assess the frequency of methylation of negative regulators of Wnt signaling: CXXC4, DACT2, HDPR1, and FBXW11 and Shh signaling: HHIP, PTCH1, SUFU, ZIC1, and ZIC4 and correlate it with clinicopathological features in this group of patients.Methylation-specific PCR was used to detect gene promoter methylation, and real-time PCR was used to assess gene expression level.The analysis of the occurrence of gene promoter methylation in head and neck carcinoma cell lines indicated that CXXC4, DACT2, HHIP, ZIC1, and ZIC4 are methylated in these tumors. These genes were further analyzed in tumor sections from oral and laryngeal cancer patients. Gene methylation rate was higher in laryngeal tumors. The methylation index in tumor samples correlated with the overall survival in a subgroup of oral cancer patients who died of the disease. Moreover, ZIC4 methylation correlated with lymph node involvement in oral cancer patients.Our findings corroborate that the activation of Wnt signaling in head and neck squamous cell carcinoma (HNSCC) is related to epigenetic silencing of its negative regulators. Moreover, the results indicate that the same mechanism of activation may operate in the case of Shh signaling.The methylation of ZIC4 may be considered a new prognostic marker in oral cavity and oropharyngeal tumors. Further investigations should determine the diagnostic significance of methylation of ZIC4, HHIP, and DACT2 in head and neck carcinomas

New insight into the role of PTCH1 protein in serous ovarian carcinomas.

The Hedgehog (Hh) signaling pathway is essential for normal embryonic development, while its hyperactivation in the adult organism is associated with the development of various cancers. The role of the Hh signaling pathway in ovarian cancer has not been sufficiently investigated. Therefore, the present study investigated the role of protein patched homolog 1 (PTCH1), a component of the Hh signaling pathway, and changes in the promoter methylation status of the corresponding gene in a cohort of low‑(LGSC) and high‑grade serous ovarian carcinomas (HGSC) and HGSC cell lines (OVCAR8 and OVSAHO). PTCH1 protein expression level was analyzed using immunohistochemistry in tissue samples and immunofluorescence and western blotting in cell lines. DNA methylation patterns of the gene were analyzed using methylation‑specific PCR. PTCH1 protein expression was significantly higher in HGSCs and LGSCs compared with controls (healthy ovaries and fallopian tubes). Similarly, ovarian cancer cell lines exhibited significantly higher PTCH1 protein expression compared with a normal fallopian tube non‑ciliated epithelial cell line (FNE1). PTCH1 protein fragments of different molecular weights were detected in all cell lines, indicating possible proteolytic cleavage of this protein, resulting in the generation of soluble N‑terminal fragments that are translocated to the nucleus. DNA methylation of the gene promoter was exclusively detected in a proportion of HGSC (13.5%) but did not correlate with protein expression. PTCH1 protein was highly expressed in serous ovarian carcinoma tissues and cell lines, while promoter methylation was only detected in HGSC. Further investigation is required to elucidate the possible mechanisms of PTCH1 activation in serous ovarian carcinomas.This research was co‑financed by the European Union through the Europe Regional Development Fund, Operational Programme Competitiveness and Cohesion (grant no. KK.01.1.1.01.0008; Reproductive and Regenerative Medicine‑Exploring New Platforms and Potentials)

Epigenetic Regulation of Hedgehog Signaling Pathway as Novel Therapeutic Approach in Breast Cancer

The Hedgehog signaling pathway is a central player in developmental transformation facilitating many cellular functions such as differentiation, proliferation and survival. Consequently, any alterations in this pathway results in cellular deficiencies leading to disease conditions especially cancer. Constitutive activation of the HH pathway responsible for initiation, maintenance or proliferation of neoplastic changes is usually a result of genetic mutations of the HH pathway components or mediated by epigenetic modifications directed aberrant expression of the pathway components. While the genetic factors accountable for aberrant activity of the pathway have been extensively studied, the epigenetic machinery behind the deregulation hasn’t been properly understood. The present study has been conducted to decipher the epigenetic regulatory mechanism controlling HH pathway in breast cancer. Elucidation of the detailed epigenetic system behind the mismanagement of this crucial pathway will highlight the significance of developmental pathways in tumorigenic states. A better knowledge regarding the epigenetic causal factors involved in deregulation of HH pathway will provide opportunities for devising novel strategies for inhibiting its activity and result in better therapeutic and clinical implications for cancer treatment

Genetic and gene expression analysis of nasopharyngeal carcinoma (NPC)

We examined both the chromosomal copy number changes and differential RNA expression profiles in Nasopharyngeal carcinoma (NPC). Gene expression profiles identified a large number of differentially regulated genes involved in diverse functional processes, while genetic analysis detected extensive genomic abnormalities including large and small, discrete regions of copy number change and loci that exhibit uniparental disomy (UPD). The relationship between chromosomal copy number and level of gene expression were analysed. This revealed that the direct copy number/expression link applies in about 60% of the instances of copy number loss/down-expression and less than 35% of instances of copy number gain/up-expression that were examined. Signalling pathway analysis revealed that numerous components involved in the TGF-β, Wnt/β-catenin and Hedgehog pathways were universally upregulated in NPC tumours, and gene expression pattern of the C666-1 cell line approximated to other NPC tumours, indicating that it is a good tumour model. A preliminary in vitro investigation of signalling pathways revealed that the C666-1 cell line is intact in the activin and Hh signalling pathways but not in the TGF-β pathway. However, the C666-1 cells appear to resist activin-mediated cell growth inhibitio

Current Advances on Non-Melanoma Skin Cancer

The book is devoted to the design, application and characterization of thin films and structures, with special emphasis on optical applications. It comprises ten papers—five featured and five regular—authored by scientists all over the world. Diverse materials are studied and their possible applications are demonstrated and discussed—transparent conductive coatings and structures from ZnO doped with Al and Ga and Ti-doped SnO2, polymers and nanosized zeolite thin films for optical sensing, TiO2 with linear and nonlinear optical properties, organic diamagnetic materials, broadband optical coatings, CrWN glass molding coatings, and silicon on insulator waveguides

Hedgehog signaling and cross-talk therapeutic potential

Hedgehog signaling and cross-talk therapeutic potentia