GBM can be diagnosed quickly with the development of imaging and directional biopsy techniques. However, among the current findings on molecular genetic characteristics, including IDH mutation, PTEN mutation, EGFR amplification and TP53 mutation, have not changed the prognosis of GBM, patients with GBM relapse quickly after surgery and have a very short survival. As molecular genomics develops rapidly, conventional diagnostics and treatments may be improved with the help of specific diagnostic and prognostic biomarkers. As a result, this study investigated the impact of CRGs on the prognosis of GBM patients, and various bioinformatics analyses were used to identify key CRGs with excellent prognostic value in GAM. Subsequently, Prognostic risk models for GBM patients were constructed using PLAUR, GP6, C5AR1, SERPINA5, F2RL2. Besides, the characteristics of tumor microenvironment infiltration in different risk populations were explored, thus providing new ideas for the treatment of patients with GBM.
Malignant tumors can provoke changes in the blood vessels, stroma, and microenvironment when they are genetically altered. All changes in inflammation, angiogenesis, and tissue repair procedures can contribute to the local and systemic activation of the clotting system. Biological processes of tumor growth, initiation, dormancy, invasion, angiogenesis, metastasis, and therapeutic response are affected by abnormal coagulation function in malignant tumors. A driver mutation in key oncogenes that is synergistic with hypoxia, differentiation, and other factors alters the expression of tissue factors and a number of hemostat-associated molecules, including transmembrane receptors such as protease-activating receptors(PAR−1,PAR−2) and clotting factors (FII and FVII)[25].
Evidence suggests that subpopulations of specific malignancies, including GBM, differ in their expression profiles of CRGs[26]. In GBM, the coagulation cascade interacts with endothelial cells and angiogenic activity to drive growth and invasion. A clotting cascade alone cannot explain glioma progression. Throughout the course of GBM, A variety of complex interactions trigger the coagulation cascade, including tumor hypoxia, upregulation of VEGR expression, and increases in both tumor cell-specific tissue factor (TF) expression and inducible TF expression in numerous intrinsic regulatory pathways[27]. It remains unclear whether the coagulation cascade leads to GBM progression or whether GBM progression leads to hypercoagulability. A study carried out by the author showed that all five prognostic biomarker genes (PLAUR, GP6, C5AR1, Serpina5, F2RL2) were highly expressed among patients at high risk, which might be involved in the development of GBM through the coagulation pathways. Several studies have reported an association between PLAUR and tumor progression. Using immunohistochemistry and real-time quantitative PCR[28–29], PLAUR expression was very high in GBM, but virtually undetectable in LGG, indicating that PLAUR may be one of the characteristic genes of GBM. A study have shown that PLAU and PLAUR expression was positively correlated with invasion, angiogenesis, epithelial-mesenchymal transformation, tumor stem cell-like characteristics, and metastasis in GBM[30]. PLAUR activation promotes extracellular protease cascades involved in tumor matrix remodeling and cell migration. It has not been reported whether Glycoprotein 6(GP6) is differentially expressed in gliomas. Breast cancer has high levels of GP6, which are significantly higher than adjacent tissues[31]. A genetic signature associated with clots has been studied in breast cancer, which suggests that GP6 may influence GBM processes through angiogenesis as well. CA5R1 is a receptor for complement CA5, and cancer survivors with high expression have a poorer prognosis[32]. Based on immunohistochemistry and transcription-level expression validation by real-time PCR, C5AR1 was highly expressed in GBM[33]. In order to defend the body from harm, complement and coagulation play an important role. Each plays a different role in physiology and pathophysiology of the systemic circulation, but their functions are interconnected[34]. SERPINA5 regulates hemostasis and thrombosis across multiple organs. There are no reports of the expression relationship of Serpin peptidase inhibitor A member 5 (SERPINA5) in GBM, but a large number of cancers, including hepatocellular carcinoma[35], gastric cancer[36], thyroid cancer[37], are highly expressed in SERPINA5. Researchers found that LGG patients with high SERPINA5 expression had a poor prognosis[38]. In other words, SERPINA5 is highly expressed in LGG patients, and LGG may progress to GBM. Although it is rare to find a report on coagulation factor II thrombin receptor-like 2 (F2RL2) in studies on gliomas, F2RL2 was revealed to be a promising biomarker for glioma in a recent analysis. The protease-activated receptor−3(PAR3) plays a key role in inflammatory reactions and immune responses, as well as tumorigenesis and metastasis in many types of cancer, including gliomas. PAR3 is encoded by F2Rl2,which is a G-protein-coupled receptor (GPCR). As a result, we hypothesized that F2Rl2 is related to PAR3 through inflammatory processes in primary gliomas[39]. In conclusion,There may be a close relation between all five prognostic biomarker genes (PLAUR, GP6, C5AR1, Serpina5, F2RL2) and the progression of glioma.
The potential value in predicting the prognosis of GBM for these characteristic genes were explored .with ROC analysis, it is suggested that AUCs at 1, 3 and 5 years were all greater than 0.6. Randomly, patients were grouped into high-risk and low-risk groups according to their median risk scores. Low-risk survivors had longer survival times than high-risk survivors, supporting the validity of the risk model. Moreover, risk models as well as treatment modalities were considered independent predictors of GBM survival. Nomogram for clinical utilize was validated as well.
Based on the results of the GO and KEEG functional enrichment analysis of 5 prognostic biomarkers, almost all of them were related to blood coagulation. It appears that coagulation plays an important role in GBM progression. In single-cell functional analysis, biomarkers F2RL2, PLAUR and SERPINA5 were significantly correlated with cell invasion, metastasis, inflammation, repair and other functions. According to the tumor immune microenvironment analysis, high-risk patients had significantly higher matrix scores, immune scores, as well as ESTIMATE composite scores. As compared to the low-risk group, there were significant differences between the five types of immune cells: Macrophages M2, mast cells resting, neutrophils, NK cells activated, and T cells CD4 memory resting. According to these results,the immune microenvironment appears to play a significant role in GBM development. The interaction between the tumor microenvironment, coagulation, inflammation and immunization plays an important role throughout the tumor's life cycle[40].
In the study for GBM, CRGs were independently identified for the first time as having a prognostic effect through the bioinformatic analysis. The relationship between the prognostic signature and immune cell infiltration in GBM was investigated as well. It is essential to observe the characteristics of GBM from an entirely new perspective in order to understand its potential pathogenesis. It has been demonstrated that PLAUR and C5AR1 are involved in glioma cell growth. The GP6, SERPINA5 and F2RL2 need to be studied in more clinical experiments, as well as further mechanistic studies to verify the prognostic utility of the CRGs-based risk model. In the future, we will continue to investigate the prognostic role of these genes, which are essential steps in predicting GBM disease progression and managing treatment.