口腔白斑病（OLK）和口腔扁平苔藓（OLP）是口腔黏膜的常见癌前病变。环状RNA（circRNAs）在OLK和OLP中的作用尚不清楚。本研究旨在评估OLK和OLP的circRNA表达谱，并进一步探讨circRNA在这两种疾病发病机制中的潜在作用。利用高通量测序技术检测了OLK（n=6），OLP（n=6），口腔鳞状细胞癌（n=6）和正常口腔黏膜组织（n=6）中差异表达的circRNA。通过qRT-PCR、酶耐受性实验和Sanger测序验证了所选circRNA的表达。在20个组织样品对中进行了扩大样本数验证。通过GO和KEGG富集分析，分析了差异circRNA所涉及的生物过程和信号通路。使用TargetScan和MiRanda预测circRNA下游miRNA，并绘制竞争性内源性RNA网络图。OLK和OLP中有49个circRNA发生了显著改变，包括30个上调和19个下调的circRNA。通过qRT-PCR、Sanger测序和RNase R实验验证了这五个所选的circRNA。GO和KEGG分析显示上调的circHLA-C可能参与了OLK和OLP的免疫功能生物过程。生物信息学分析表明circHLA-C可能作为ceRNA参与了OLK和OLP的进展。在扩大样本数验证中，PCR结果显示circHLA-C在OLK和OLP中明显上调。ROC分析表明circHLA-C具有潜在的诊断价值，并具有良好的准确性和特异性。我们的研究揭示了circHLA-C是OLK和OLP中存在的最显著上调的circRNA，并就circHLA-C在OLK和OLP的病因发病和进展中的作用进行了初步讨论。

Oral leukoplakia (OLK) and oral lichen planus (OLP) are common precancerous lesions of the oral mucosa. The role of circular RNAs (circRNAs) in OLK and OLP is unclear. The aim of this study was to evaluate the circRNA expression profiles of OLK and OLP, and further explore the potential role of circRNAs in the pathogenesis of these two diseases.High throughput sequencing technology was performed to detect the differentially expressed circRNA in OLK (n = 6), OLP (n = 6), oral squamous cell carcinoma (n = 6), and normal oral mucosa tissues (n = 6). Expression of selected circRNAs was validated by qRT-PCR, enzyme tolerance assay, and Sanger sequencing. Expanded sample size validation was done in 20 tissue pairs. The biological processes and signal pathways involved in differential circRNA were analyzed by GO and KEGG enrichment. TargetScan and MiRanda were used to predict miRNAs downstream of circRNA and draw competitive endogenous RNA network diagram.Forty-nine circRNAs were significantly altered in OLK and OLP, including 30 upregulated and 19 downregulated circRNAs. The five selected circRNAs were validated by qRT-PCR, Sanger sequencing, and RNase R assay. GO and KEGG analyses indicated that the upregulated circHLA-C may be involved in the biological process of immune function of OLK and OLP. Bioinformatics analysis indicated that circHLA-C may be involved in the progression of OLK and OLP as a ceRNA. In validation with expanded sample size, PCR results showed that circHLA-C expression was significantly upregulated in OLK and OLP. ROC analysis indicated that circHLA-C has potential diagnostic value with good accuracy and specificity.Our study revealed that circHLA-C is the most significantly upregulated circRNA co-existing in OLK and OLP, and we preliminarily discuss the role of circHLA-C in the etiopathogenesis and progression of OLK and OLP.