Gene analysis of ameloblastoma-derived cells treated with retinoic acid

Abstract

Ameloblastoma is one of the most common benign odontogenic tumors in the oral cavity, and may recur because it grows in a locally invasive manner. Although many studies have been performed on ameloblastoma, its bioactive characteristics remain unclear. Retinoic acid, a metabolite of fat-soluble vitamin A, which is used as a leukemia drug, has been demonstrated to have antitumor effects on some tumor types. We examined whether retinoic acid has potential as a new remedy for ameloblastoma. We found that retinoic acid inhibited the proliferation of cells derived from ameloblastoma and induced differentiation. However, its intracellular signaling and regulatory mechanisms remain unclear. In this study, we primarily cultured cells from ameloblastoma to elucidate signal transduction, and examined the differences in gene expression levels due to retinoic acid action by microarray analysis. Surgically removed specimens were obtained with consent of the patients from the Second Department of Oral and Maxillofacial Surgery, Osaka Dental University Hospital. Primary culture was started with medium for the epithelium, followed by cloning to be used as ameloblastoma cells. Subsequently, retinoic acid was added at a final concentration of 10-6 to 10-7 M and incubated for 6 hours to prepare an experimental group. A control group was also prepared without addition of retinoic acid. After culturing, the cells were collected to extract RNA from each group for microarray analysis.

In the experimental group, increase in the expression of the EDF1 gene was most pronounced, whereas that of the TM4SF10 gene was most markedly suppressed. Furthermore, the expression levels of the MMP3 and FGF2 genes were suppressed by 0.37- and 0.48-fold, respectively. The regulation of cell growth and differentiation comprises comprehensive regulatory mechanisms, such as protein synthesis, degradation, complex formation, and phosphorylation, in addition to gene expression. Our study suggested that changes in the expression of FGF2 and MMP3 genes are partly involved in the inhibition of growth and promotion of differentiation by retinoic acid in ameloblastoma-derived cells. (J Osaka Dent Univ 2020; 54: 145-151)