Fig. 5

STC2 is associated with an immunosuppressive microenvironment in osteosarcoma patients. A, B Correlation analysis between STC2 and the infiltration of CD8+ T cells as well as the type II interferon response pathway in TARGET-OS cohort. C Correlation in mRNA expression between STC2 and type II interferon related genes in TARGET-OS cohort. D Correlation between protein levels of STC2 and CD8+ T cells infiltration was evaluated through immunohistochemistry staining in osteosarcoma patients (p < 0.0001, R =  − 0.3515, n = 62). E, F qPCR and Western blot analysis of the expression of MHC-I molecules in STC2 knockdown 143B and SJSA-1 cells. G, H Correlation between protein levels of STC2 and MHC-I molecules through immunohistochemistry staining in osteosarcoma patients. I Schematic workflow for osteosarcoma cell and T cells co-culture system. Naive T cells were in vitro stimulated with CD3/CD28 antibodies in the presence of interleukin (IL)-2 (1.5 ng/ml). J, K Activated T cells were co-cultured with osteosarcoma cells, and CD8+ T cells function markers were determined by flow cytometry. *p < 0.05, **p < 0.01, ***p < 0.001