Molecular basis for the epigenetic regulation of MGP in cancer

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Publication . Caiado, Helena Isabel Rosa Pinto; Cancela, Leonor; Conceição, Natércia

Matrix Gla protein (MGP) is a member of the vitamin K-dependent family of proteins and a known physiological inhibitor of ectopic calcifications. Mutations in its gene cause Keutel syndrome, a rare autosomal recessive disorder characterized by severe soft tissue calcification. Despite its involvement in multiple calcifying pathologies, MGP has been described as playing a potential role in carcinogenesis, thus contributing to trigger interest in this gene towards exploring its potential as a cancer prognostic factor. These findings lead us to the main objective of this work which consisted of the study of the MGP gene in different types of tumors, to identify possible epigenetic patterns and transcriptional regulators responsible for controlling MGP gene expression in cancer. In this sense, we analyzed the expression pattern of MGP at mRNA and protein levels in a variety of tumors, initially using tissue biopsies from colorectal patients, and then exploring, through bioinformatics analysis, the data available in The Cancer Genome Atlas and The Human Protein Atlas. Results demonstrated a correlation between high levels of MGP with advanced stages of cancer progression and poor overall survival outcome, establishing MGP as an independent prognostic factor for the patient’s overall survival We also evaluated the methylation status in four of the six CpG sites, located in the MGP promoter region (cg13302154; cg22221831, and cg00431549) and first intron (cg0560958), between healthy and tumoral tissue. Results showed a correlation between MGP mRNA expression and the different methylation patterns across all the analyzed tumors, providing evidence for epigenetic regulation of MGP transcription. Moreover, we investigated several putative transcriptional regulators through transient transfections with luciferase reporter assays, demonstrating that YY1, GATA1, and C/EBPα are negative regulators of the MGP promoter. Altogether, our data contribute to provide novel insights on MGP regulation, strengthening the hypothesis that MGP plays a role during cancer progression/proliferation.

2022-12-14Doctoral thesis

Open access

Evaluation of MGP gene expression in colorectal cancer

Publication . Caiado, Helena; Conceição, Natércia; Tiago, Daniel; Marreiros, Ana; Vicente, Susana; Enriquez, Jose Luis; Vaz, Ana Margarida; Antunes, Artur; Guerreiro, Horacio; Caldeira, Paulo; Leonor Cancela, M.

Purpose: Matrix Gla protein (MGP) is a vitamin K-dependent, gamma-carboxylated protein that was initially found to be a physiological inhibitor of ectopic calcifications affecting mainly cartilage and the vascular system. Mutations in the MGP gene were found to be responsible for a human pathology, the Keutel syndrome, characterized by abnormal calcifications in cartilage, lungs, brain and vascular system. MGP was recently implicated in tumorigenic processes such as angiogenesis and shown to be abnormally regulated in several tumors, including cervical, ovarian, urogenital and breast. This fact has triggered our interest in analyzing the expression of MGP and of its regulator, the transcription factor runt related transcription factor 2 (RUNX2), in colorectal cancer (CRC). Methods: MGP and RUNX2 expression were analyzed in cancer and non-tumor biopsies samples from 33 CRC patients and 9 healthy controls by RT-qPCR. Consequently, statistical analyses were performed to evaluate the clinical-pathological significance of MGP and RUNX2 in CRC. MGP protein was also detected by immunohistochemical analysis. Results: Showed an overall overexpression of MGP in the tumor mucosa of patients at mRNA level when compared to adjacent normal mucosa and healthy control tissues. In addition, analysis of the expression of RUNX2 mRNA demonstrated an overexpression in CRC tissue samples and a positive correlation with MGP expression (Pearson correlation coefficient 0.636; p <= 0.01) in tumor mucosa. However correlations between MGP gene expression and clinical-pathological characteristics, such as gender, age and pathology classification did not provide relevant information that may shed light towards the differences of MGP expression observed between normal and malignant tissue. Conclusions: We were able to associate the high levels of MGP mRNA expression with a worse prognosis and survival rate lower than five years. These results contributed to improve our understanding of the molecular mechanism underlying MGP deregulation in cancer.

2020-01Journal article

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