Siglec15 was highly expressed in NSCLC and was correlated with spinal metastasis. (A) The expression profiles of Siglec15 mRNA in NSCLC (n=979) and normal lung tissues (n=108) based on TCGA database are represented. (B,C) Data collected from TCGA database showed the relative expression of Siglec15 mRNA in TCGA-LUAD (n=533) and TCGA-LUSC (n=499) tissues and normal lung tissues (n=55, n=50). (D-H) Siglec15 mRNA expression and the relationship between tumor stage, T stage, lymph node metastasis, overall survival, and disease-free survival in TCGA-NSCLC. (I) Heatmap of bone metastasis-related genes expression between the high- and low-Siglec15 expression groups. (J) Correlation analysis between Siglec15 expression and bone metastasis-related genes expression based on the MSigDB. (K) The levels of Siglec15 protein expression in human primary NSCLC tissues (primary) and NSCLC SM tissues were examined by western blotting. (L) Siglec15 protein expression in human normal lung and primary NSCLC, as well as NSCLC spinal metastasis tissues were examined by IHC. Scare bar =50 μm. NSCLC, non-small cell lung cancer; TCGA, The Cancer Genome Atlas; LUAD, lung adenocarcinoma; LUSC, lung squamous carcinoma; MSigDB, Molecular Signatures Database; SM, spinal metastasis; IHC, immunohistochemistry.