Down-Regulation of Long Non-Coding RNA TINCR Induces Cell Dedifferentiation and Predicts Progression in Oral Squamous Cell Carcinoma

Zehang Zhuang; Jing Huang; Weiwang Wang; Cheng Wang; Pei Yu; Jing Hu; Haichao Liu; Hanqi Yin; Jinsong Hou; Xiqiang Liu

doi:10.3389/fonc.2020.624752

Down-Regulation of Long Non-Coding RNA TINCR Induces Cell Dedifferentiation and Predicts Progression in Oral Squamous Cell Carcinoma

Front Oncol. 2021 Feb 25:10:624752. doi: 10.3389/fonc.2020.624752. eCollection 2020.

Authors

Zehang Zhuang^{1

2}, Jing Huang^{1

2}, Weiwang Wang^{1

2

3}, Cheng Wang^{1

2}, Pei Yu^{4

5}, Jing Hu^{1

2}, Haichao Liu^{1

2}, Hanqi Yin^{6

7}, Jinsong Hou^{1

2}, Xiqiang Liu⁸

Affiliations

¹ Department of Oral and Maxillofacial Surgery, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.
² Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China.
³ Department of Oral and Maxillofacial Surgery, Xiangya Hospital, Central South University, Changsha, China.
⁴ Department of Prothodontics, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China.
⁵ Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangzhou, China.
⁶ State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.
⁷ South China Institute of Biomedine, Guangzhou, China.
⁸ Department of Oral and Maxillofacial Surgery, NanFang Hospital, Southern Medical University, Guangzhou, China.

Abstract

Objectives: Recently long non-coding RNAs (lncRNAs) have emerged as novel gene regulators involved in tumorigenic processes, including oral squamous cell carcinoma (OSCC). Here, we identified a differentiation-related lncRNA, terminal differentiation-induced non-coding RNA (TINCR). However, its biological function and clinicopathological significance in OSCC still remain unclear.

Methods: The lncRNA expression profiles in OSCC tissues and paired adjacent non-tumor tissues (NATs) from 10 patients were detected by lncRNA microarrays. Weighted gene co-expression network analysis (WGCNA) and gene ontology (GO) enrichment were performed to identify the most significant module and module functional annotation, respectively. Potential differentiation-related lncRNAs were screened by differential expression analysis. TINCR was further confirmed in OSCC cell lines and tissues of another patient cohort by using qRT-PCR. The correlation between the TINCR expression level and clinicopathological characteristics was analyzed. The effects of TINCR on cell differentiation, migration and invasion were assessed by knockdown or knock-in in vitro and in vivo.

Results: WGCNA and GO enrichment analysis showed that one co-expression network was significantly enriched for epithelial cell differentiation, among which, TINCR was significantly downregulated. qRT-PCR analyses validated down-regulation of TINCR in tumor tissues compared with paired NATs, and its expression was closely correlated with pathological differentiation and lymph node metastasis in patients with OSCC. Patients with lower TINCR expression levels had worse survival. Cell function experiments showed that TINCR played a crucial role in epithelial differentiation. Both TINCR and epithelial differentiation-associated genes, including IVL and KRT4, were significantly upregulated during OSCC cell calcium-induced differentiation but were reduced when cell dedifferentiation occurred in tumor spheres. Overexpression of TINCR dramatically suppressed cell dedifferentiation, migration and invasion in vitro, while knockdown of TINCR had the opposite effects. Upregulation of TINCR significantly elevated the expression of terminal differentiation genes and repressed tumor growth in vivo. Moreover, TINCR significantly suppressed the activation of JAK2/STAT3 signaling in OSCC cells.

Conclusion: Our study suggests that TINCR functions as a tumor suppressor by inducing cell differentiation through modulating JAK2/STAT3 signaling in OSCC. TINCR may serve as a prognostic biomarker and therapeutic target for OSCC.

Keywords: OSCC (oral squamous cell carcinoma); TINCR (tissue differentiation-inducing non-protein coding RNA); cell differentiation; lncRNAs (long non-coding RNAs); metastasis; progression.