Clinical Features and Differential Gene Screening of Invasive Behaviors between Glioma and Brain Metastasis

Original Article

Austin J Clin Neurol 2022; 9(1): 1159.

Clinical Features and Differential Gene Screening of Invasive Behaviors between Glioma and Brain Metastasis

Zeng X¹, Chen G¹, Dong M², Feng L², Chu L² and Liu J¹*

1Guizhou Medical University, Guiyang, Guizhou, People’s Republic of China

2Department of Neurosurgery, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, People’s Republic of China

*Corresponding author: Jian Liu, Guizhou Medical University, Guiyang, Guizhou550004, China

Received: October 22, 2022; Accepted: November 18, 2022; Published: November 25, 2022

Abstract

Objective: To analyze invasive behaviors between glioma and Brain Metastasis (BM), and to screen invasive differentially expressed genes.

Methods: Patients diagnosed pathologically with glioma or BM divided into low-grade glioma groups (n = 19), high-grade glioma group (n = 18), and BM group (n = 15). The survival period was determined. The clinical characteristics were retrospectively analyzed to draw Kaplan-Meier survival curve. Glioma and BM samples were obtained for RNA sequencing. By GO, KEGG, PubMed, and GeneCard, invasive genes were theoretical selected. Correlation between invasive genes and pathological grade was performed. The expression level of invasive genes was verified.

Results: The survival curve found that the clinical invasive behavior related to short lifetime includes: size, edema range, blood supply, vascular invasion, grade, and Ki 67 expression. Theoretical analysis finally found that the expression levels of CALM3, CAMK2A, CAMK2B, and PRKCG were negatively correlated with pathological grade (P< 0.01), of which CALM3 was highly correlated with BM (P< 0.01). CALM3 mRNA was significantly down-regulated in BM (P< 0.05), and PRKCG mRNA was significantly down-regulated in both glioma and BM (P< 0.05).

Conclusion: The clinical invasive behavior between glioma and BM have significantly shortened the median survival time of patients. Down-regulation of CALM3 suggested a higher correlation with BM, meanwhile Down-regulation of PRKCG played a role in glioma and BM The detection of CALM3 and PRKCG may be helpful for invasive behavior and provide a reference for the targeted therapy in glioma and BM.

Keywords: Glioma; Brain metastasis; Bioinformatics; Neoplasm invasiveness

Introduction

Intracranial malignant tumor, characterized by its localization and local invasive growth, the disease exhibits high mortality and high disability rate. In general, intracranial malignant tumor can be divided into primary tumor and Brain Metastasis (BM).

Glioma accounts for nearly 30% of all primary brain tumors, and is the main cause of death of primary brain tumors [1]. The histological classification of gliomas is based on Bailey and Cushing’s embryonic theory and Kernohan’s anamorphology theory, which are astrocytoma, oligodendroglioma, oligoastrocytoma, ependymoma, and choroid plexus epithelioma. According to WHO’s central nervous system tumor classification in 2016, molecular typing is included in the diagnostic criteria for the first time, such as Isocitrate Dehydrogenase (IDH) wild/mutant, H3K27M mutant, 1p/19q codeletion, RELA fusion, WNT/SHH activation, TP 53 wild/mutant etc., performing individualized treatment and clinical prognosis analysis in patients [2]. However, the molecular typing and corresponding clinical significance of gliomas need to be further proved. The main reason is that clinical outcomes from current surgical outcomes, chemotherapy drugs, and radiotherapy, are not ideal [3]. The overall prognosis of patients with gliomas is still poor. The median survival time of glioblastoma is 1 year, and the 5-year mortality rate exceeds 95% [4]. With the deepening of research, most patients with gliomas have been confirmed to have polygenic mutations [5]. Therefore, it may provide guidance for improving the prognosis of glioma patients in studying the gene function network, finding a new gene mutation, using differentially expressed genes to add the molecular genetic diagnosis, and elaborating the potential regulatory mechanism.

Most neoplastic brain injuries are caused by cancers outside the central nervous system. Studies have shown that BM is the most common intracranial malignant tumor in adults. The incidence of peripheral BM is 10% -40%. The number of BM patients is about 10 times that of primary brain tumors. The median survival time of BM without treated is about 2 months, and can be extended to about 5 months after treatment [6]. The primary lesion of BM is lung cancer, followed by breast cancer, as well as malignant melanoma, gastrointestinal tumors, and kidney cancer [7]. Clinically, although BM patients have tried a variety of surgical-based treatment strategies, the results are not good [8]. By observing changed gene in BM tissues, and corresponding analysis with gliomas, it is possible to discover the underlying regulatory mechanism of BM, which has certain guiding significance for the clinical diagnosis and treatment [9].

At present, the genomic variation of gliomas is still a hot spot. The relational research can be divided into the following 7 groups [10]: telomerase reverse transcriptase (TERT, rs2736100), Epidermal growth factor receptor (EGFR), coiled-coil domain containing 26 mutant group (CCDC26, rs55705857), cyclin dependent kinase inhibitor 2B mutant group (CDKN2B, rs1412829), PH homologous domain B family member 1 mutation group (PHLDB1, rs498872), tumor protein p53 mutation group (TP53, rs78378222),and telomere extension Helicase regulator mutant group (RTEL1, rs6010620).The study of glioma genome variation not only analyzes the biological function and signaling pathway, but also guides clinical diagnosis and treatment plans. For example, the mutations of CCDC26 and PHLDB1 are associated with IDH variant gliomas, suggesting that patients have a lower relapse rate and longer survival time. The 1p/19q co-deletion is of great significance in the pathological diagnosis of oligodendroglioma, the evaluation of the efficacy of radiotherapy and chemotherapy, and the prediction of clinical prognosis, which is related to the variation of TERT. On the other hand, BM shows the characteristics of primary gene mutations, for example, nonsmall cell lung cancer (NSCLC) often takes EGFR mutation [11] and anaplastic lymphoma kinase gene (Anaplastic Lymphoma Kinase, ALK) Rearrangement. Breast cancer can be driven by human epidermal growth factor receptor 2 [12]. Melanoma often demonstrates BRAF V600E mutation.BM also illustrates intracranial malignant tumor characteristics in genes, such as TP53, NRAS, And KRAS mutations, DSC2, ST7, PIK3R1 and SMC mutations, etc. In short, genomic mutations of gliomas and BM provide ideas for new therapeutic targets.

Gene Sequencing, a high-throughput technology combining life science and microelectronics technology, has been widely studied and applied in various research fields of biology and medicine in recent years. It provides important theoretical and practical value for sequence analysis, gene expression, genome research, and hybridization signal intensity analysis with gene expression profiles. Accompanied large-scale, high-throughput information, a series of biological information in brain tumor research is integrated [13]. Zhu XP et al. [14] studied the expression characteristics of micro RNAs of different grades of gliomas through gene micro-matrix technology. Ondracek J et al. [15] discovered the full micro RNA expression profile of radio resistant glioblastoma cells. Bhawe KM et al. [16] formulated some principles of gene chip application in glioblastoma. Then, the expression profile of exons of gliomaswas found [17], and Protein- Protein Interactions (PPI) network construction and hierarchical cluster analysis were conducted [18]. It suggests the application of gene chip technology in the regulatory mechanism of gliomas.In addition, whole-gene high-throughput analysis of BM has also been reported [19]. However, there are few studies on the comparative analysis of differential genes between gliomas and BM.

This study collected samples and clinical data of glioma and BM, analyzing the clinical features of aggressive behavior, exploring the different genes between gliomas and BM by RNA sequencing (RNAseq), screening the invasive genes with bioinformatics principles, and finally verifying invasive genes by quantitative real-time polymerase chain reaction (qRT-PCR), which aimed at the molecular mechanism of intracranial malignant tumor progression.

Materials and Methods

Ethical Approval

The clinical data and tumor specimens pathologically diagnosed gliomas or metastases were collected from November 2017 to November 2019. The procedure was approved by the Ethics Committee of Guizhou Medical University and affiliated hospital (IRB-2019-152). All procedures performed in studies related to human participants were in accordance with the 1964 Declaration of Helsinki and its later amendments.

Clinical Data Recording and Grouping

52 patients were divided into low-grade glioma group (group A, n = 19), high-grade glioma group (group B, n = 18), BM group (group C, n = 15) .Gender, age, tumor location, tumor size, edema range, chief complaint, preoperative KPS, surgical approach, tumor blood supply, vascular invasion, presence or absence of cystic changes, degree of resection, tumor grade, and Ki 67 expression were recorded.

Specimen Collection and Processing

According to the operation plan, RNAwait (Solarbio, Beijing, China), cryotube, 4°C physiological saline, ice box, sterile instrument bag, sterile syringe, liquid nitrogen and liquid nitrogen were prepared 2h in advance. In the operating room environment, the tumor tissues (cancer tissues and adjacent tissues 3 cm away from the lesion center) were washed with normal saline, placed into cryotube in pieces, and put into a liquid nitrogen tank within 10 minutes. After 24 h, the tissues were transferred to a refrigerator at -80°C for future use.

RNA-seq

The RNA-seq process was supported by Shanghai Jinteda Gene Technology Co., Ltd (NO. G2016083036XM). Briefly, after conventional RNA extraction, Nanodrop 2000 (Thermo Fisher Scientific, Waltham, Massachusetts, USA) determined the nucleic acid protein ratio A260/A280. The RNA concentration was measured on the Qubit 2.0 platform (Thermo Fisher Scientific, Waltham, Massachusetts, USA). 4200 TapeStation detected (Agilent Technologies, Santa Clara, California, USA) RNA RIN value. OligodT magnetic bead method was used to establish and amplify the mRNA library.

Bioinformatics Analysis

According to the previous report, the amplified sequences were analyzed using the next-generation sequencing comparison tools HISAT2 [20] and Stringtie [21]. Differentially expressed genes were obtained after correction using Fold-Change (FC). The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to enrich and annotate differentially expressed genes. After selection of invasion biological pathways involves genes, the reduced target invasion genes are confirmed by literature screening and human tissue expression.

qRT-PCR

cDNA was synthesized according to the instructions of the reverse transcription™ first strand cDNA synthesis Kit (Thermo Fisher Scientific, Waltham, Massachusetts, USA). Amplification was performed according to FastStart Universal SYBR Green Master (Roche, Basel, Switzerland). The reaction parameters set by the PCR instrument: pre-denaturation at 95°C for 2 min, denaturation at 95°C for 15 s, annealing for 20 s (Table 1) and extension at 60°C for 40 s. 40 cycles in total. after manual correction, the relative expression level were calculate by 2-ΔΔCt method. The sequence of the primers is shown in the (Table 1), synthesized by Beijing Solarbio company reference (http://asia.ensembl.org/).