Prognosis prediction and tumor immune microenvironment characterization based on tryptophan metabolism-related genes signature in brain glioma.

in Frontiers in pharmacology by Shuxin Zhang, Siliang Chen, Zhihao Wang, Junhong Li, Yunbo Yuan, Wentao Feng, Wenhao Li, Mina Chen, Yanhui Liu

TLDR

  • The study looked at how the way a group of genes related to tryptophan metabolism in the brain (TrMGs) are expressed in glioma patients affects their prognosis and the immune microenvironment of their tumors. The study found that patients with higher expression of these genes had a worse prognosis and were less likely to respond to immunotherapy. The study also found that these genes were positively correlated with the expression of immunotherapy targets, such as PD1 and PD-L1, and with more immune cell infiltration in the tumor. The study suggests that these genes could be used as a prognostic model for glioma patients and may help identify patients who would benefit from immunotherapy.

Abstract

Glioma is the most common malignant tumor in the central nervous system with no significant therapeutic breakthrough in recent years. Most attempts to apply immunotherapy in glioma have failed. Tryptophan and its metabolism can regulate malignant features of cancers and reshape immune microenvironment of tumors. However, the role of tryptophan metabolism in glioma remains unclear. In current study, we explored the relationships between the expression pattern of tryptophan metabolism-related genes (TrMGs) and tumor characteristics, including prognosis and tumor microenvironment of gliomas through analyzing 1,523 patients' samples from multiple public databases and our own cohort. Based on expression of TrMGs, K-means clustering analysis stratified all glioma patients into two clusters with significantly different TrMG expression patterns, clinicopathological features and immune microenvironment. Furthermore, we constructed a tryptophan metabolism-related genes signature (TrMRS) based on seven essential TrMGs to classify the patients into TrMRS low- and high-risk groups and validated the prognostic value of the TrMRS in multiple cohorts. Higher TrMRS represented for potentially more active tryptophan catabolism, which could subsequently lead to less tryptophan in tumor. The TrMRS high-risk group presented with shorter overall survival, and further analysis confirmed TrMRS as an independent prognostic factor in gliomas. The nomograms uniting TrMRS with other prognostic factors manifested with satisfactory efficacy in predicting the prognosis of glioma patients. Additionally, analyses of tumor immune landscapes demonstrated that higher TrMRS was correlated with more immune cell infiltration and "hot" immunological phenotype. TrMRS was also demonstrated to be positively correlated with the expression of multiple immunotherapy targets, including PD1 and PD-L1. Finally, the TrMRS high-risk group manifested better predicted response to immune checkpoint inhibitors. In conclusion, our study illustrated the relationships between expression pattern of TrMGs and characteristics of gliomas, and presented a novel model based on TrMRS for prognosis prediction in glioma patients. The association between TrMRS and tumor immune microenvironment of gliomas indicated an important role of tryptophan and its metabolism in reshaping immune landscape and the potential ability to guide the application of immunotherapy for gliomas.

Overview

  • The study explores the relationships between the expression pattern of tryptophan metabolism-related genes (TrMGs) and tumor characteristics, including prognosis and tumor microenvironment of gliomas through analyzing 1,523 patients' samples from multiple public databases and their own cohort. The study aims to identify the role of tryptophan metabolism in glioma and develop a prognostic model based on TrMGs.

Comparative Analysis & Findings

  • The study identified two clusters of glioma patients with significantly different TrMG expression patterns, clinicopathological features, and immune microenvironment. The TrMRS low-risk group had better overall survival than the high-risk group. The nomograms uniting TrMRS with other prognostic factors manifested with satisfactory efficacy in predicting the prognosis of glioma patients. The TrMRS high-risk group manifested better predicted response to immune checkpoint inhibitors. The study also demonstrated that higher TrMRS was correlated with more immune cell infiltration and
  • hot
  • immunological phenotype. TrMRS was also demonstrated to be positively correlated with the expression of multiple immunotherapy targets, including PD1 and PD-L1.

Implications and Future Directions

  • The study highlights the importance of tryptophan and its metabolism in reshaping immune landscape and the potential ability to guide the application of immunotherapy for gliomas. The findings suggest that TrMRS could be used as a prognostic model for glioma patients and may help identify patients who would benefit from immunotherapy. Future research could further explore the role of tryptophan metabolism in glioma and investigate the potential of immunotherapy targeting tryptophan metabolism for glioma treatment.
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