Expression of WNT genes in cervical cancer-derived cells: Implication of WNT7A in cell proliferation and migration

According to the multifactorial model of cervical cancer (CC) causation, it is now recognized that other modifications, in addition to Human papillomavirus (HPV) infection, are necessary for the development of this neoplasia. Among these, it has been proposed that a dysregulation of the WNT pathway might favor malignant progression of HPV-immortalized keratinocytes. The aim of this study was to identify components of the WNT pathway differentially expressed in CC vs. non-tumorigenic, but immortalized human keratinocytes. Interestingly, WNT7A expression was found strongly downregulated in cell lines and biopsies derived from CC. Restoration of WNT7A in CC-derived cell lines using a lentiviral gene delivery system or after adding a recombinant human protein decreases cell proliferation. Likewise, WNT7A silencing in non-tumorigenic cells markedly accelerates proliferation. Decreased WNT7A expression was due to hypermethylation at particular CpG sites. To our knowledge, this is the first study reporting reduced WNT7A levels in CC-derived cells and that ectopic WNT7A restoration negatively affects cell proliferation and migration.

Epigenetic mechanisms in the development of memory and their involvement in certain neurological diseases

INTRODUCTION

Today, scientists accept that the central nervous system of an adult possesses considerable morphological and functional flexibility, allowing it to perform structural remodelling processes even after the individual is fully developed and mature. In addition to the vast number of genes participating in the development of memory, different known epigenetic mechanisms are involved in normal and pathological modifications to neurons and therefore also affect the mechanisms of memory development.

DEVELOPMENT

This study entailed a systematic review of biomedical article databases in search of genetic and epigenetic factors that participate in synaptic function and memory.

CONCLUSIONS

The activation of gene expression in response to external stimuli also occurs in differentiated nerve cells. Neural activity induces specific forms of synaptic plasticity that permit the creation and storage of long-term memory. Epigenetic mechanisms play a key role in synaptic modification processes and in the creation and development of memory. Changes in these mechanisms result in the cognitive and memory impairment seen in neurodegenerative diseases (Alzheimer disease, Huntington disease) and in neurodevelopmental disorders (Rett syndrome, fragile X, and schizophrenia). Nevertheless, results obtained from different models are promising and point to potential treatments for some of these diseases.

Peripheral T-lymphocytes express WNT7A and its restoration in leukemia-derived lymphoblasts inhibits cell proliferation

Background

WNT7a, a member of the Wnt ligand family implicated in several developmental processes, has also been reported to be dysregulated in some types of tumors; however, its function and implication in oncogenesis is poorly understood. Moreover, the expression of this gene and the role that it plays in the biology of blood cells remains unclear. In addition to determining the expression of the WNT7A gene in blood cells, in leukemia-derived cell lines, and in samples of patients with leukemia, the aim of this study was to seek the effect of this gene in proliferation.

Methods

We analyzed peripheral blood mononuclear cells, sorted CD3 and CD19 cells, four leukemia-derived cell lines, and blood samples from 14 patients with Acute lymphoblastic leukemia (ALL), and 19 clinically healthy subjects. Reverse transcription followed by quantitative Real-time Polymerase chain reaction (qRT-PCR) analysis were performed to determine relative WNT7A expression. Restoration of WNT7a was done employing a lentiviral system and by using a recombinant human protein. Cell proliferation was measured by addition of WST-1 to cell cultures.

Results

WNT7a is mainly produced by CD3 T-lymphocytes, its expression decreases upon activation, and it is severely reduced in leukemia-derived cell lines, as well as in the blood samples of patients with ALL when compared with healthy controls (p ≤0.001). By restoring WNT7A expression in leukemia-derived cells, we were able to demonstrate that WNT7a inhibits cell growth. A similar effect was observed when a recombinant human WNT7a protein was used. Interestingly, restoration of WNT7A expression in Jurkat cells did not activate the canonical Wnt/β-catenin pathway.

Conclusions

To our knowledge, this is the first report evidencing quantitatively decreased WNT7A levels in leukemia-derived cells and that WNT7A restoration in T-lymphocytes inhibits cell proliferation. In addition, our results also support the possible function of WNT7A as a tumor suppressor gene as well as a therapeutic tool.

[Diseases caused by triplet expansion]

INTRODUCTION

Today we know of a group of mutations caused by the expansion of nucleotide triplets, which are very unstable in meiosis and mitosis. Four types of triplets have the capacity for pathogenic expansion in human beings (CGG/ GCC, CAG/GTC, CTG/GAC and GAA/CTT) and maybe located both in coding sequences (bulbospinal muscular atrophy, Huntington's disease and certain spinocerebellar ataxias) and non-coding sequences (fragile X syndrome, Friedreich's ataxia, myotonic dystrophy). Trinucleotide expansion may lead to gains or losses in gene functioning and seems to be associated to a variety of factors, some of which are directly related with the expansive process (cis-acting) and others whose interaction with the triplets helps to make them increasingly more unstable (trans-acting). Medium-sized expansions (pre-mutations), although clinically silent, do show a marked tendency to expand into complete mutations during the transition along the germinal line. The models that have been proposed to explain triplet expansion involve gene recombination and replication processes; however, they have not fully succeeded in explaining the phenomena related to mutation or phenotypic expression in these diseases.

DEVELOPMENT

This work examines the most recent concepts related to the dynamic mutation processes that give rise to human diseases; it also reviews the most important clinico-biological aspects observed in those diseases.

CONCLUSIONS

Dynamic mutation processes represent a new concept in the molecular biology of gene mutations. An ever increasing number of pathologies are caused by this type of DNA alterations, which, as a whole, display very interesting clinico-biological characteristics.