Journal of Prevention and Treatment for Stomatological Diseases ›› 2021, Vol. 29 ›› Issue (5): 296-305.doi: 10.12016/j.issn.2096-1456.2021.05.002

• Basic Study • Previous Articles     Next Articles

Differential expression profile of circRNAs in oral leukoplakia

XU Siming1(),SONG Yuhan1,SHAO Yanxiong1,TAO Lan2(),ZHOU Haiwen1()   

  1. 1. Department of Oral Mucosal Diseases, Shanghai Ninth People′s Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai Research Institute of Stomatology, Shanghai 200011, China
    2. Department of General Dentistry, Shanghai Ninth People′s Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai Research Institute of Stomatology, Shanghai 200011, China
  • Received:2020-09-25 Revised:2020-12-04 Online:2021-05-20 Published:2021-03-08
  • Contact: Lan TAO,Haiwen ZHOU;;
  • Supported by:
    The National Natural Science Foundation of China(81170968)


Objective To investigate the differences and clinical significance of circRNA expression profiles in oral leukoplakia (OLK) tissues and normal oral mucosal (NOM) tissues. Methods High-throughput sequencing was used to detect differentially expressed circRNAs in 6 pairs of OLK and NOM tissues, and qRT-PCR was used to verify the expression of 10 circRNAs screened in 6 pairs of OLK and NOM tissues. The ring formation of circRNA was verified by RNase R digestion and Sanger sequencing, and the target circHLA-C was further verified by qRT-PCR in 20 pairs of OLK and NOM tissues. CircHLA-C was visualized using the UCSC genome browser ( The function of differentially expressed circRNAs was analyzed by GO and KEGG enrichment analyses. TargetScan and miRanda predicted the downstream miRNAs and mRNAs of the target circRNAs, and a ceRNA network related to the identified circRNAs was constructed in Cytoscape. Results Sequencing analysis showed that 366 circRNAs were significantly differentially expressed in OLK tissues, including 65 upregulated and 301 downregulated circRNAs. After qRT-PCR verification, 7 of the 10 screened circRNAs were expressed consistent with the sequencing results. The upregulated circHLA-C was confirmed to be a real circRNA with back-splice junction sites by RNase R digestion and Sanger sequencing. Correlation analysis showed a positive correlation between circHLA-C and the degree of OLK dysplasia. ROC curve analysis suggested that circHLA-C had potential value in diagnosing OLK with high accuracy and specificity. Conclusion CircRNA was significantly abnormally expressed in OLK tissues, and the upregulation of circHLA-C may be related to the degree of OLK dysplasia, providing guiding value for the diagnosis of OLK in the future.

Key words: circRNA, oral leukoplakia, premalignant lesion, high-throughput sequencing, differential expression profile, competing endogenous RNA, miRNA, circHLA-C, epithelial dysplasia

CLC Number: 

  • R781.5

Table 1

The clinical characteristics of patients with oral leukoplakia for sequencing"

Number Age (year) Sex Location Dysplasia degree Smoking history (No/Yes) Alcohol history (No/Yes)
1 47 Female Dorsal of the tongue Mild No No
2 61 Female Ventral of the tongue Mild No No
3 41 Male Ventral of the tongue Mild No No
4 51 Female Ventral of the tongue Mild-moderate No No
5 69 Male Ventral of the tongue Mild-moderate No Yes
6 52 Female Buccal Moderate-severe No No

Table 2

The primers used for qRT-PCR experiments"

Circular RNA Primer type Primer sequence (5’-3’)

Figure 1

Expression profiles of circRNAs in OLK versus NOM tissues a: hierarchical clustering analysis showed circRNA expression profles that were different between OLK tissues and NOM tissues; red represents upregulated circRNAs, and green represents downregulated circRNAs; b: scatter plot of differences in circRNA expression between OLK and NOM tissues; red represents upregulated circRNAs with FC ≥ 2.0 in OLK tissues; green represents downregulated circRNAs with FC ≥ 2.0; c: volcano plot of signifcantly dysregulated circRNAs in OLK tissues; red represents eligible circRNAs (FC ≥ 2.0; P < 0.05). OLK: oral leukoplakia; NOM: normal oral mucosal"

Figure 2

Distribution of the characteristics of significantly dysregulated circRNAs a: significantly differentially expressed circRNAs were divided into 4 types according to the host gene structure(exon, intron, antisense, and sense overlapping circRNA); b: filtered circRNAs were classified by whether they were newly discovered; c: classification according to the circRNA length; d: chromosome distribution of upregulated and downregulated signifcantly differentially expressed circRNAs"

Table 3

Ten circRNAs differentially expressed in OLK"

CircRNA ID FC P Chromosome Strand Gene name Sequence length(bp)
CircHLA-C(chr6:31238920-31324013-) 7.719 < 0.001 chr6 - HLA-C 85 094
CircPLIN4(chr19:4511523-4511918-) 5.992 0.001 chr19 - PLIN4 396
CircMTX2(chr2:177161588-177202305+) 5.980 0.003 chr2 + MTX2 40 718
CircRNF13(chr3:149613260-149639014+) 5.735 0.002 chr3 + RNF13 379
CircSENP2(chr3:185293003-185344181+) -8.583 < 0.001 chr3 + SENP2 51 179
CircPLEKHM2(chr1:16044388-16047883+) -6.122 < 0.001 chr1 + PLEKHM2 435
CircERICH1(chr8:618598-624047-) -5.917 < 0.001 chr8 - ERICH1 954
CircEMB(chr5:49694941-49707217-) -5.722 < 0.001 chr5 - EMB 12 277
CircALDH3A2(chr17:19554860-19575269+) -5.532 0.006 chr17 + ALDH3A2 1 290
CircZNF720(chr16:31733947-31734674+) -5.258 0.001 chr16 + ZNF720 223

Figure 3

Ten circRNAs differentially expressed in OLK a: ten selected circRNAs were subjected to qRT-PCR validation in 6 NOM and 6 OLK tissues; b: comparison of the results of high-throughput sequencing and qRT-PCR. c: RNase R analysis showed that circHLA-C, circPLIN4 and circRNF13 resisted digestion by RNase R; *:P < 0.05. OLK: oral leukoplakia; FC: fold change; HLA-C: human leukocyte antigen-C; PLIN4: perilipin-4; MTX2: metaxin 2; RNF13: ring finger protein 13; SENP2: sentrin/SUMO-specific proteases; PLEKHM2: pleckstrin homology and RUN domain containing M2; ERICH1: glutamate rich 1; EMB: embigin; ALDH3A2: aldehyde dehydrogenase 3 family member A2; ZNF720: zinc finger protein 720"

Figure 4

Ring formation mechanism and back spliced site of circHLA-C HLA-C: human leukocyte antigen-C"

Figure 5

KEGG analysis of the differential expression of circRNA in OLK a: top 10 in the KEGG analysis of upregulated circRNAs; b: top 10 in the KEGG analysis of downregulated circRNAs. The terms in the red frame indicate important pathways in OLK; OLK:oral leukoplakia"

Figure 6

ROC curve analysis of circHLA-C in OLK OLK: oral leukoplakia"

Figure 7

CeRNA interaction ceRNA:competing endogenous RNA"

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