Microarray and quantitative RT-PCR analyses in calcium-channel blockers induced gingival overgrowth tissues of periodontitis patients.

Objectives: The purpose of the present study was to analyse transcriptomes and mRNA expression levels for specific genes in calcium-channel blocker-induced gingival overgrowth (GO) tissues.

Design: Eight gingival tissues samples (from both GO negative and positive sites) were harvested from four GO patients for microarray analyses. Twelve candidate genes were selected for further quantitative real time reverse transcription-polymerase chain reaction (qRT-PCR) analyses. Ten GO tissues from periodontitis patients and ten control gingival tissues from healthy subjects were compared by qRT-PCR. Mann-Whitney U-test was used for statistical evaluation.

Results: In GO positive tissues, 163-1631 up-regulated and 100-695 down-regulated genes were identified with more than two-fold changes compared with GO negative tissues amongst patients by microarray experiments. No commonly expressed genes amongst the eight sets of microarray data were found. The clustering analysis confirmed that the entire transcriptome patterns showed similarities in individuals, but differences amongst the four patients. The qRT-PCR and statistical analyses for the candidate genes, though, revealed differential gene expressions between GO-positive and negative tissues. We found that matrix metalloproteinase (MMP)-1 and MMP-12 as well as cathepsin-L were significantly up-regulated whilst keratin-10 and transforming growth factor-β1 were significantly down-regulated in GO tissues of periodontitis patients compared with the control gingival tissues of healthy subjects.

Conclusion: The microarray analyses revealed that GO pathogenesis was complex and individually varied, though GO-affected gingival tissues were controlled at least by genes related to collagen metabolisms including regulated MMPs, cathepsin-L, growth factors, and keratins to maintain tissue homeostasis in vivo.