Developmental Differences in Circular RNA Expression Between Adult and Fetal Human Salivary Glands Based on Public Total RNA-Sequencing Data

Circular RNAs (circRNAs) are stable regulatory RNAs whose developmental patterns in human salivary glands remain poorly defined. Publicly available total RNA-seq data from adult and fetal salivary glands (GSE143702—adult, n = 13; fetal, n = 14) were analyzed to profile the circRNA expression and evaluate developmental-stage differences. Reads were aligned with STAR using chimeric detection, circRNAs were parsed and annotated with CIRCexplorer2, and circRNAs supported by ≥2 back-splice junction reads were retained for quantification. Principal component analysis (PCA) of circRNA expression profiles demonstrated significant (PERMANOVA p = 0.001) separation between adult and fetal salivary glands, with a moderate effect size (R² = 0.118). Differential expression analysis identified 18 circRNAs that were significantly (adjusted p < 0.05) upregulated in adult salivary glands, with three additional circRNAs showing evidence suggestive of differential expression (0.05 ≤ adjusted p < 0.10). In fetal salivary glands, 18 circRNAs were significantly upregulated, with eight additional circRNAs showing suggestive evidence. For functional context, stage-associated circRNAs were linked to predicted miRNA interactions using the circAtlas 3.0 database and then to experimentally supported miRNA target genes using the miRTarBase database. These findings provide a stage-resolved overview of salivary gland circRNAs throughout development and aid in the prioritization of candidates for downstream validation.