MicroRNA Expression Profiles in External Cervical Resorption.
INTRODUCTION
External cervical resorption (ECR) has been challenging for its diagnosis, prevention, and treatment. Its etiology and pathogenesis are largely unknown. This study characterized microRNA (miRNA) expression patterns of human tissues from ECR lesions and identified potential messenger RNA targets and pathways.


METHODS
Granulomatous tissues from ECR (n = 5) and their adjacent nonaffected asymptomatic gingival connective tissues (n = 5) were collected. Similarly, chronic periodontitis (CP) and control samples were collected (n = 3). Quantitative reverse transcription polymerase chain reaction array analysis compared the expression profiles of 88 miRNAs between diseases. Differentially expressed miRNAs were identified using the Student t test. Bioinformatics for messenger RNA (miRWalk) and KEGG pathway analyses were performed to identify predicted target genes and biological/cellular functions and signaling pathways.


RESULTS
Three miRNAs (miR-20a-5p, miR-210-3p, and miR-99a-4p) were significantly down-regulated and 1 miRNA (miR-122-5p) was significantly up-regulated in ECR (P < .05). One up-regulated and 1 down-regulated miRNA reached the significance threshold in CP. A comparison of miRNA expression in ECR and CP identified 3 differentially expressed miRNAs, indicating differences in disease pathobiology. Inflammation-associated Wnt, PI3K-Akt, mitogen-activated protein kinases signaling, and bone formation-associated transforming growth factor beta pathways were identified and predicted to be modulated by differentially expressed miRNAs in both ECR and CP. Biological processes unique to each disease entity were identified, such as T- and B-cell receptor signaling pathways, osteoclast differentiation, and extracellular matrix-receptor interaction for CP. Glycosaminoglycan biosynthesis, mineral absorption, and insulin signaling pathways for ECR were identified.


CONCLUSIONS
This proof-of-principle in vivo study indicated that ECR has both common and unique miRNA expression profiles in comparison with CP, which are predicted to target genes regulating inflammation, immunity, and metabolism of mineralized tissues.
['Pettiette|Mary T|MT|', 'Zhang|Shaoping|S|', 'Moretti|Antonio J|AJ|', 'Kim|Steven J|SJ|', 'Naqvi|Afsar R|AR|', 'Nares|Salvador|S|']
D019295:Computational Biology D020869:Gene Expression Profiling D006801:Humans D035683:MicroRNAs D010518:Periodontitis D019869:Phosphatidylinositol 3-Kinases D015398:Signal Transduction
microRNA external cervical resorption Chronic periodontitis inflammation