Abstract:

Objective To discuss the expression levels of Eps15 homology domain-containing protein 2 （EHD2）， microRNA let-7c （miR-let-7c）， and long non-coding RNA （lncRNA） FOXD2-AS1 in laryngeal squamous cell carcinoma （LSCC） tissue， and to clarify the association between EHD2/miR-let-7c/FOXD2-AS1 signaling axis and occurrence of LSCC. Methods Forty LSCC tissue samples were collected and classified into low grade group （moderately or high differentiated， 32 cases） and high grade group （poorly differentiated， 8 cases） according to the pathology results； according to the tumor node metastasis（TNM） clinical staging results， the samples were divided into TNM early stage group （stages Ⅰ-Ⅱ， 13 cases） and TNM late stage group （stages Ⅲ-Ⅳ， 27 cases）； based on the lymph node metastasis results， the samples were divided into metastasis group （21 cases） and non-metastasis group （19 cases）. Additionally， 40 corresponding normal adjacent tissue samples were collected as control group. Immunohistochemistry method was used to detect the expressions of EHD2 in various groups and its relationships with clinical pathoparameters of the LSCC patients were analyzed； bioinformatics method was used to confirm that the miR-let-7c was the candidate microRNA（miRNA） and FOXD2-AS1， which had binding sites in its promoter region， was a candidate lncRNA. Ten pairs of fresh LSCC tissue samples and adjacent normal tissue samples were collected. Real-time fluorescence quantitative PCR （RT-qPCR） method was used to detect the expression levels of EHD2 mRNA， miR-let-7c， and FOXD2-AS1 in the samples in two groups， and their associations were verified. Results Compared with adjacent normal tissue， the expression level of EHD2 in LSCC tissue was significantly decreased （P<0.01）. The positive expression rate of EHD2 in LSCC tissue of the patients in TNM early stage group was significantly higher than that in TNM late stage group （P<0.05）. There was no significant association between EHD2 expression and pathological type or lymph node metastasis （P>0.05）. Compared with control group， the expression level of miR-let-7c in LSCC tissue was significantly decreased （P<0.05）， while the expression level of FOXD2-AS1 was significantly increased （P<0.05）. In LSCC tissue， the expression level of FOXD2-AS1 was negatively correlated with the expression level of miR-let-7c （r=-0.67，P<0.05）， and the expression level of miR-let-7c was negatively correlated with the expression level of EHD2 mRNA（r=-0.83， P<0.01）. Conclusion EHD2 and miR-let-7c both express at low levels in LSCC tissue and may be new tumor suppressor genes； FOXD2-AS1 is highly expressed in LSCC tissue and may be a new oncogene. FOXD2-AS1/miR-let-7c/EHD2 signaling axis may be involved in the occurrence and development of LSCC.

Key words: Eps15 homologous domain protein 2, MicroRNA-let-7c, Laryngeal squamous cell carcinoma, Long-chain non-coding RNA, Proto-oncogene