A common variant in the precursor miR-146a sequence does not predispose to cholangiocarcinoma in a large European cohort.
BACKGROUND
Micro-RNAs (miRNAs) are small, non-coding RNA species considered to fine-tune basic cellular functions by modulating target gene translation and/or mRNA stability. A common G/C polymorphism (rs2910164) in the precursor (pre-) miR-146a gene engaged in NF-κB signaling and apoptosis pathways has been reported to modulate the genetic risk of hepatocellular carcinoma by increased G-allelic production of mature miR-146a. We investigated rs2910164 in a large European-based cholangiocarcinoma (CCA) cohort.


METHODS
We recruited 182 CCA patients and 350 controls in three academic medical centers. Genotyping for rs2910164 was performed by PCR-based assays with 5'-nuclease and fluorescence detection. Genotype frequencies were tested for consistency with the Hardy-Weinberg equilibrium using an exact test; allelic and genotypic differences between the patients and controls were assessed by the Chi-square test and Armitage's trend test. Exploratory subgroup analyses included gender, tumor localization (extra- versus intrahepatic CCA) and early-onset CCA.


RESULTS
Genotype distributions were consistent with the Hardy-Weinberg equilibrium. No significant differences in either allele or genotype distributions were detected between the CCA and control groups or the respective subgroups investigated. However, there was a trend for a protective effect of the heterozygous single-nucleotide polymorphism state GC, as indicated by an underrepresentation in the CCA group in general (29% vs 35%; P=0.18) and, in particular, for extrahepatic tumor sites (26% vs 35%; OR=0.67; 95% CI, 0.43-1.02; P=0.065).


CONCLUSIONS
Our data do not support a prominent contribution of the pre-miR-146a sequence variant in the genetic predisposition to CCA. However, current studies functionally characterizing rs2910164 have proposed that distinct repertoires of target genes are addressed by genotype-specific mature miR-146a species. Given the detected trend towards a potentially protective role of GC heterozygosity, a subtle modulation of genetic CCA risk by the pre-miR-146a GC genotype may exist and should be evaluated further.
Department of Medicine II, Saarland University Hospital, Homburg 66421, Germany.
Florentina
F
Mihalache
Aksana
A
Hoblinger
Monica
M
Acalovschi
Tilman
T
Sauerbruch
Frank
F
Lammert
Vincent
V
Zimmer
D000046:Academic Medical Centers; D000368:Aged; D001650:Bile Duct Neoplasms / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D001653:Bile Ducts, Intrahepatic / Q000473:pathology; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D018281:Cholangiocarcinoma / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D015331:Cohort Studies; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005858:Germany / Q000453:epidemiology; D006579:Heterozygote; D006801:Humans; D016015:Logistic Models; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010641:Phenotype; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D012322:RNA Precursors / Q000235:genetics*; D018570:Risk Assessment; D012307:Risk Factors; D012383:Romania / Q000453:epidemiology
C542542:MIRN146 microRNA, human; D035683:MicroRNAs; D012322:RNA Precursors