SPP1 as a key gene in the lymph node metastasis and a potential predictor of poor prognosis in head and neck carcinoma

Background Lymph node metastasis (LNM) is an important cause leading to recurrence and development of head and neck carcinoma (HNC), with the precise mechanisms unclear. Thus, we aimed to identify the key genes involved in LNM and further evaluate their expressions and roles. Methods A cohort of HNC in the TCGA was analyzed. The study involved three phases (one screening and two validation phases). First, the differentially expressed genes regarding LNM were screened, from which a key gene was identified by a series of data mining approaches. Then, the expressions and roles of the key gene were validated in HNC through bioinformatics. Afterward, the expression of the key gene was detected by qPCR, western blot, and Immunohistochemistry based on a cell model and a tissue microarray. Further, colony formation and transwell migration and invasion assays were used to evaluate the roles of the key gene. Results SPP1 was overexpressed in HNC tissues and was identified as the key gene. Overexpression of SPP1 in HNC was correlated with advanced pathological stages and T-stage, as well as the presence of LNM, which predicted poor prognosis. The expression of SPP1 was closely associated with the infiltration of immune cells in HNC, especially M2 macrophages. Lab experiments confirmed that SPP1 silence in HNC cells resulted in weakened invasive and metastatic abilities. Conclusion This study reveals that SPP1 may be a key gene associated with LNM in HNC, raising the possibility of SPP1 as a target for HNC prevention and treatment.