Analysis of Immune–Stromal Score-Based Gene Signature and Molecular Subtypes in Osteosarcoma: Implications for Prognosis and Tumor Immune Microenvironment

Abstract

Objective: Infiltrating immune and stromal cells are essential for osteosarcoma progression. This study set out to analyze immune–stromal score-based gene signature and molecular subtypes in osteosarcoma.Methods: The immune and stromal scores of osteosarcoma specimens from the TARGET cohort were determined by the ESTIMATE algorithm. Then, immune-stromal score-based differentially expressed genes (DEGs) were screened, followed by univariate Cox regression analysis. A LASSO regression analysis was applied for establishing a prognostic model. The predictive efficacy was verified in the GSE21257 dataset. Associations between the risk scores and chemotherapy drug sensitivity, immune/stromal scores, PD-1/PD-L1 expression, immune cell infiltrations were assessed in the TARGET cohort. NMF clustering analysis was employed for characterizing distinct molecular subtypes based on immune-stromal score-based DEGs.Results: High immune/stromal scores exhibited the prolonged survival duration of osteosarcoma patients. Based on 85 prognosis-related stromal–immune score-based DEGs, a nine-gene signature was established. High-risk scores indicated undesirable prognosis of osteosarcoma patients. The AUCs of overall survival were 0.881 and 0.849 in the TARGET cohort and GSE21257 dataset, confirming the well predictive performance of this signature. High-risk patients were more sensitive to doxorubicin and low-risk patients exhibited higher immune/stromal scores, PD-L1 expression, and immune cell infiltrations. Three molecular subtypes were characterized, with distinct clinical outcomes and tumor immune microenvironment.Conclusion: This study developed a robust prognostic gene signature as a risk stratification tool and characterized three distinct molecular subtypes for osteosarcoma patients based on immune–stromal score-based DEGs, which may assist decision-making concerning individualized therapy and follow-up project.

Single-cell RNA datasets and bulk RNA datasets analysis demonstrated C1Q+ tumor-associated macrophage as a major and antitumor immune cell population in osteosarcoma

“…Osteosarcoma (OS) represents the most frequent and primary bone sarcoma, which primarily affects children, adolescents, and young adults ( 1 ). The standard therapy for OS, comprising surgery and chemotherapy, was established in the 1980s and resulted in long-term survival in >60% of patients presenting with localized disease ( 2 ); however, limited therapeutic progress has been made since that time.…”

“…Infiltrating immune and stromal cells are essential for OS progression ( 1 ). The immune infiltration level was considered an important factor in response to immunotherapy and prognosis.…”

“…The immune infiltration level was considered an important factor in response to immunotherapy and prognosis. Analyses of the tumor microenvironment (TME) of OS consistently demonstrate an immune cell infiltration consisting of both macrophages and T cells ( 1 , 3 , 4 ). Primary OS is demonstrated as “immune deserts,” devoid of T cells and NK cells ( 5 , 6 ).…”