SUMMARY

Lung adenocarcinoma (LUAD) is the most common type of lung cancer and it is one of the main causes of cancer deaths globally, it is characterized by distinct cellular and molecular features. LUAD gene mutations could influence carcinogenesis, metastasis, and treatment outcomes. The purpose of this research is to identify new gene mutations in the endothelial nitric oxide synthase (eNOS or NOS3) and cystathionine γ-lyase (CSE or CTH) genes which are linked to various LUAD symptoms.
Biochemical analysis including liver function test: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and bilirubin, and renal function test including: urea and creatinine parameters for 20 serum samples of LUAD patients and 20 serum samples of control or healthy individuals was done in order to examine the prognostic value of liver and renal function tests as prospective prognostic markers in LUAD by comparing to the that of healthy individuals. In formalin-fixed paraffin-embedded (FFPE) samples from 31 LUAD patients, Sanger sequencing was used to identify gene polymorphisms in two genes. Real-time polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) were used to examine epidermal growth factor receptor (EGFR) mutations and programmed death-ligand 1 (PD-L1) expression in 110 LUAD patients. Mutations in the selected genes were obtained from the gnomAD database for all cancer types and from the Mutagene and COSMIC databases for LUAD patients, and the interaction between the studied genes was predicted using the GeneMANIA prediction server.
A significant difference of biochemical parameters results between LUAD patients group and control group was observed. Level of liver enzyme (AST, ALT and ALP), liver metabolism of bilirubin and renal waste products (urea and creatinine) significantly increased in LUAD patients compared to serum of healthy individuals. The polymorphism data revealed 189 mutations in the NOS3 gene and 31 mutations in the CTH gene. Among the 110 LUAD patients, 14 (12.73%) samples were PD-L1 positive and expressed 50% or more PD-L1 protein. While 8 (7.27%) of the samples had EGFR mutations, including 2 deletions and 2 point mutations in exon 19, 2 point mutations (c.2573T>G p.(Leu858Arg), and 2 point mutations (p.L858R) in exon 21. In gnomAD, there are 4012 mutations in the NOS3 gene and 1214 mutations in the CTH gene. The NOS3 gene had the most mutations (295 and 93) in the Mutagene and COSMIC databases, while the CTH gene had (61 and 36) mutations, respectively. According to the GeneMANIA prediction server, there are 10 genes associated with the NOS3 gene, 8 genes associated with the CTH gene, 15 genes associated with the EGFR gene, and 5 genes associated with the PD-L1 gene. Poorly and moderately differentiated tumours predominated, and the most prevalent stage was pT3 N2 Mx, followed by pT2 N1 Mx.
In conclusion, the findings of this study are the first to identify and combine many previously unknown mutations in LUAD patients’ NOS3 and CTH genes, this has clinical implications for LUAD patients.