Expression analysis of autophagy protein and mTOR protein in oral squamous cell carcinoma

ZHANG Fei; GAO Hua; ZHAI Xing-hua; SU Ming; YIN Xu-bin

doi:10.19749/j.cn.cjgd.1672-2973.2024.05.003

Abstract：Objective To compare the expression levels of autophagy-related proteins and mTOR pathway proteins in tumors and their adjacent tissues of patients with oral squamous cell carcinoma (OSCC) and to explore the correlation between autophagy proteins and mTOR pathway protein expression. Methods Twenty-six specimens were collected from patients diagnosed with OSCC and underwent resection of the lesions in Beijing Stomatology Hospital,The specimen tissues were divided into three groups,in which the tumor group(T) was the tissues in the central area of the tumor,the normal group(N) was the normal tissues 2 cm away from the edge of the tumor lesion,and the junction tissues (margin group M) were the tissues in between the two groups. Immunofluorescence assay and protein immunoblotting assay were used to detect the expression levels of autophagy-related proteins LC3-Ⅱ and p62 in each group of samples,Immunohistochemical staining method and protein immunoblotting assay were used to detect the expression levels of mTOR pathway-related proteins,and to explore the correlation between the expression levels of autophagy-related proteins and mTOR pathway-related proteins by the Spermann' s correlation analysis method. Results The findings of immunofluorescence experiments showed that the expression levels of LC3-Ⅱ and p62 were higher in both the tumor group and the junction group than in the normal group. Significantly,the expression levels of LC3-Ⅱ and p62 were higher than those of the normal group in both the junction group and the tumor group (both P<0.001),and the differences between the tumor group and the junction group were not statistically significant (P>0.05). Immunohistochemistry results showed that the expression of mTOR and 4E-BP1 and their levels of phosphorylated 4E-BP1 were higher in the tumor and margin groups than in the normal group. The results of protein immunoblotting experiments also showed that the levels of mTOR and 4E-BP1 and their phosphorylation were the highest in the margin group,followed by the tumor group,and the lowest in the normal group (all P<0.01);whereas p70S6K and its phosphorylation levels did not differ statistically between groups (P>0.05). Spermann correlation analysis showed that the expression levels of LC3-Ⅱ and p62 were positively correlated in both tumor and margin groups (both P<0.05),and mTOR was positively correlated with the expression levels of LC3-Ⅱ and p62 in both tumor and margin groups (both P<0.05). Conclusions OSCC patients have active mTOR pathway and impaired autophagic flow process in the central region of the tumor and the tumor-normal tissue junction region,and targeted inhibition of the mTOR pathway provides a new proposal for the clinical management of OSCC patients.