The RFC1 80G>A, among Common One-Carbon Polymorphisms, Relates to Survival Rate According to DNA Global Methylation in Primary Liver Cancers.

Sara Moruzzi,Simone Conci,Patrizia Guarini,Filippo Mazzi,Nicola Martinelli,Stephanie A Tammen,Sang-Woon Choi,Francesca Pizzolo,Andrea Ruzzenente,Simonetta Friso,Silvia Udali,Patrizia Pattini,Alfredo Guglielmi,Oliviero Olivieri,Lorenzo Chiariotti

doi:10.1371/journal.pone.0167534

Sara Moruzzi, Simone Conci + Show 13 more

Open Access

https://doi.org/10.1371/journal.pone.0167534

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Journal: PloS one	Publication Date: Dec 9, 2016
Citations: 5	License type: CC BY 4.0

Affiliation: University of Verona, Tufts University

Abstract

Polymorphisms within one-carbon metabolism genes have been largely studied in relation to cancer risk for the function of this pathway in nucleotide synthesis and DNA methylation. Aims of this study were to explore the possible link among several common functional gene polymorphisms within one-carbon metabolism and survival rate in primary liver cancers, i.e., hepatocellular carcinoma and cholangiocarcinoma, and to assess the additional effect of global DNA methylation on survival rate and mortality risk. Forty-seven primary liver cancer patients were genotyped for ten polymorphisms: DHFR 19bp ins/del, TS 2rpt-3rpt, MTHFD1 1958G>A, MTHFR 677C>T, MTR 2756A>G, MTRR 66A>G, RFC1 80G>A, SHMT1 1420C>T, BHMT 716 A>G, TC II 776C>G. Methylation was determined in peripheral blood mononuclear cells (PBMCs) DNA as methylcytosine (mCyt) content using LC/MS/MS. Among the polymorphisms analysed, the RFC1 80G>A (rs1051266) influenced the survival rate in primary liver cancers. The RFC1 80AA was associated to a significantly reduced survival rate (22.2%) as compared to both GG and GA genotypes (61.5% and 76% respectively, p = 0.005). When the cancer patients were stratified according to the mCyt median value as high (>5.34%) or low (≤5.34%), the concomitant presence of AA genotype and low mCyt level led to a significantly worse survival rate as compared to the G allele carriership (p<0.0001) with a higher Hazard Ratio (HR = 6.62, p = 0.001). The subjects carrying the AA genotype in association with high mCyt did not show a significant difference in survival rate as compared with the G allele carriers (p = 0.919). The RFC1 80G>A polymorphism influenced the survival rate, and the presence of RFC1 80AA genotype with low global methylation in PBMCs DNA was associated with poorer prognosis and higher mortality risk, therefore highlighting novel molecular signatures potentially helpful to define prognostic markers for primary liver cancers.

Highlights

One-carbon metabolism is essential for several intracellular reactions including those involved in nucleotide synthesis and biological methylation, in particular methylation of DNA, the major epigenetic mechanism in mammalian cells [1].Genetic variants of one-carbon pathway genes have been investigated mainly in colon cancer as potential markers of cancer susceptibility [2,3,4,5] for the involvement of this metabolism in cellular development, proliferation and differentiation [6, 7]
The homozygous variant Reduced Folate Carrier 1 (RFC1) 80AA was associated to a lower survival rate (22.2%) as compared to both RFC1 80 GG and GA genotypes (Fig 1A)
The statistical significance increased when the RFC1 80AA subjects were compared to the G allele carriers (RFC1 80 GG + GA) (Fig 1B) with a survival rate of 22.2% versus 71.1%, respectively (p = 0.002)

Summary

Introduction

One-carbon metabolism is essential for several intracellular reactions including those involved in nucleotide synthesis and biological methylation, in particular methylation of DNA, the major epigenetic mechanism in mammalian cells [1]. Genetic variants of one-carbon pathway genes have been investigated mainly in colon cancer as potential markers of cancer susceptibility [2,3,4,5] for the involvement of this metabolism in cellular development, proliferation and differentiation [6, 7]. The molecular mechanisms underlying the possible association among polymorphic variants of one-carbon metabolism genes, cancer survival rate and mortality risk are, not completely clarified. A global hypomethylation in peripheral blood mononuclear cells (PBMCs) DNA was associated to an increased cancer risk [13] and a shorter survival rate in patients affected by different types of cancer [14,15,16]. We observed significantly reduced methylcytosine (mCyt) levels in PBMCs DNA of cancer patients [17, 18] and lower levels were directly associated to an unfavourable prognosis [18]

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