Abstract
OBJECTIVE: To investigate the expression of interleukin- 34 (IL-34) in tongue squamous cell carcinoma (TSCC) and its clinical implications. METHODS: Serum IL-34 level was detected in 36 patients with TSCC and 36 healthy individuals using enzymelinked immunosorbent assay (ELISA). The expressions of IL-34 mRNA and protein levels in TSCC and adjacent tissues were examined in 41 patients using real-time fluorescence quantitative PCR (qRT-PCR) and immunohistochemistry (IHC), and their correlation with the clinicopathological features of the patients was further analyzed. Informatic analysis of the differentially expressed genes related with IL-34 in TSCC was carried out based on String database, LinkedOmics database and GEO database, and GO functional analysis and KEGG signaling pathway enrichment analysis were performed using Webgestalt database. RESULTS: The serum level of IL-34 was significantly lower in TSCC patients than in the healthy individuals (P < 0.001), and its expression level was also significantly lower in the tumor tissues than in the adjacent tissues (P < 0.001). The expression level of IL-34 in TSCC tissues was related with lymph node metastasis and TNM staging (P < 0.05), but not with age, gender, smoking, drinking, or tumor size (P > 0.05). Informatic analysis suggested that IL-34 had the strongest correlation with CSF1R and PTPRJ. IL-34 and its related genes in TSCC were enriched mainly in bone marrow cell differentiation, collagen-containing extracellular matrix, and cytokine binding and signal receptor activator activity. KEGG signaling pathway enrichment showed that IL-34 and the related differentially expressed genes were involved mainly in osteoclast differentiation, protein polysaccharide in cancer, and the MAPK signaling pathway. CONCLUSION: IL-34 is lowly expressed in TSCC and participates in the occurrence and progression of TSCC, and can be potentially used as a new diagnostic biomarker and therapeutic target for TSCC.