The mortality rate of glioma is very high, and the current status of treatment is very worrying. A large amount of genotype-oriented disease classification principles have been introduced, which have made medical treatment possess a broad research direction [7]. We obtained three microarrays of the GEO database based on a systematic analysis method, targeting important participating genes throughout the development of glioma, and extracted four key genes. These genes play a vital role in the development of glioma. Immunotherapy is a new therapeutic method at present, which can inhibit the tumor during the treatment, and can specifically act on the tumor to achieve the effect of adjuvant therapy[8]. Part of the treatment of brain tumors has shifted to immunomodulatory intervention therapies. In gliomas, a variety of immune cell types are infiltrated, such as neutrophils, macrophages, and T cells, which are infiltrated[9,10]. Microglia and macrophages are enriched in the microenvironment, and there is a significant interaction between these cells to promote the malignant progression of gliomas[11]. At present, many recognized immune markers play an important immunoregulatory function in gliomas.IDH1 (R132H) is a neoantigen that triggers immune responses in IDH1 (R132H) mutant gliomas[12]. Programmed cell death protein and its ligands (PD-1 and PD-L1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) may be key factors for tumor cells to evade immunosuppression[13]. Unfortunately, the single-target immunotherapy effect is still not significant and patient survival is not significantly increased[14,15].We hope to search for meaningful immune research targets and promote the progress of immunotherapy.
Fibronectin 1 (FN1) is a central component of the extracellular matrix (ECM), which constructs the tumor microenvironment (TME) and participates in the invasion, migration ,immune inflistrate, and metabolism of tumor cells [16,17]. By comparing the genetic differences between grade III and IV gliomas, it is found that the genes ELAV-like protein 1(ELAVL1) and FN1 may participate in the growth of gliomas through the PI3K-Akt signaling pathway, and ECM can be found to promote tumor invasion [18]. Similar to our results, COL3A1, FN1, MMP9 and other genes can be considered to play an important role in glioblastoma, and these genes are also mainly present in ECM [19]. GBM tumor guanylate binding protein 2 (GBP2) is a large-scale GTPase induced by interferon, which can improve the immunity of microorganisms. Studies have found the role of GBP2/Stat3/FN1 signaling cascade in GBM invasion[8]. There are many genes in the TME of malignant gliomas that are related to the prognosis of the patient. These genes include LAMB1, FN1, ACTN1, TRIM, SERPINH1, CYBA, LAIR1, LILRB2[20]. Also, MIR-1 and MIR-1271 exert an inhibitory function on FN1, which can ultimately improve the effect of chemotherapy. Their low expression is all related to the poor prognosis of glioma patients[21,22].
In the process of tumor epithelialization and metastasis, LAMB1 (laminin β-1) is activated to promote the EMT process[23]. The level of protein phosphorylation in breast cancer has an obvious change, and the level of secreted phosphorylated protein group may reflect the progression and subtype of the disease. Among them, CD44, OPN, FSTL3, LAMB1, STC2 are of great significance[24]. In colorectal cancer, LAMA1, LAMA3, LAMB1 and LAMB4 are more abundant[25]. LAMB1 is superior to CEA (carcinoembryonic antigen) in distinguishing colorectal cancer patients from control groups. The combined measurement of LAMB1 and CEA may improve the accuracy of diagnosing colorectal cancer[26]. The silencing of LAMB1 and CACNA1D in prostate tissue can also reduce tumor cell infiltration[27]. These candidate genes may assist diagnosis and treatment, and predict the risk of tumor metastasis in the early stage of tumor development.
FAM20C protein is a new kinase that phosphorylates secreted proteins and proteoglycans. FAM20C phosphorylates hundreds of secreted proteins and is activated by the pseudokinase Fam20A, which is closely related to the metabolism of substances in the Golgi apparatus[28,29]. It phosphorylates many extracellular proteins, including the small integrin-binding ligand, N-linked glycoproteins [30]. Studies believe that the activator of Fam20C may be beneficial in cancer. In addition, the activator of G-CK/Fam20C may provide a new treatment tool for the field of biomineralization and low phosphate diseases [31,32]. In lung cancer, FAM20C, MYLIP ,and COL7A1 have been identified as key hypoxia-related genes in the LUAD process, and are regulated by DNA methylation [33,34]. The triple-negative breast cancer (TNBC) cells that activate FAM20C exhibit a strong anti-proliferation effect, with increased apoptosis and decreased migration [35]. There are few studies on Fam20C in gliomas. In this study, we found for the first time that the expression of FAM20C was also up-regulated in GBM. We speculate that FAM20C may also play an anti-proliferative effect as an antagonist of glioma evolution. Perhaps, its gene expression is up-regulated with the up-regulation of tumor-promoting gene expression.
The COL6A1 (VI collagen α1 ) is located on chromosome 21 and can maintain the integrity of various tissues[36].COL6A1 gene expression is significantly different in normal glial cells compared with low-grade (grade I, II) astrocytoma and high-grade astrocytoma (grade III, IV). And the difference is more obvious in high-grade samples [37,38]. Many studies have used this protein as one of the markers of epithelial-mesenchymal transition, and play an important role in tumor ECM receptor interaction and lesion adhesion pathway[39,40].
Compared with differentiated glioblastoma cells(DGCs), the expression levels of 10 proteins that interact with ECM in cancer stem cells (CSCs) are increased(COL6A1, COL6A3, FN1, ITGA2, ITGA5, ITGAV, ITGB1, ITGB3, LAMB1, and LAMC1), indicating that CSC may be highly aggressive(12). Therefore, these three genes(FN1, LAMB1, and COL6A1)are also involved in tumor recurrence, which is one of the characteristics of glioma stem cells. Considering the close connections between these three genes, it is very meaningful to explore their specific interactions in glioma. Our research screened out genes related to the prognosis of GBM as potential therapeutic targets. Moreover, in the process of glioma evolution, glioma cells can evolve their suitable microenvironment, increasing their proliferation and invasion capabilities[41]. In general, the expression of 4 genes increased during the progression from LGG to GBM. If we can regulate key microenvironment genes FN1, LAMB1, COL6A1 ,and FAM20C expression at an early stage, a good therapeutic effect may be obtained. Moreover, from the results of enrichment analysis and co-expression, it is reasonable to think that these genes may also be involved in immune-related processes.While COL6A1,FAM20C may be risk factors for immune cell infiltration and resulted in a shorter survival time for glioma patients.