Study of PD-L2 Gene Expression in Patients with NSCLC-type Subclasses of Lung Cancer Using Real-Time PCR

Introduction: Lung cancer is one of the biggest health problems in the world. Non-small cell lung cancers (NSCLCs), which account for approximately 85% of lung cancer cases, are the leading cause of deaths due to cancer worldwide. The type 1planned death molecule (PD-I, CD279) and its PD-L1 ligands (B7-H1, CD274) and PD-L2 (B7-DC, CD273) are the key molecules inhibiting the immune regulation. The aim of this study was to investigate the expression of PD-L2 gene and the evaluation of cancerous stages of NSCLC and its subclasses in lung cancer patients in Tehran hospitals using Real-Time PCR.

Materials and Methods: A total of 35 clinical samples were collected from patients with NSCLC-derived lung cancer from three hospitals in Tehran (Khatam, Athiyah and Masih Hospitals). Of the 35 samples obtained in 2017, 20% of them were women and 80% were men. The age range of patients varied from 37 to 80 years. The disease grade gradients among the patients in this investigation varied and 22 different grades were observed. To investigate the PDL-2 gene expression, after extraction of total RNA and cDNA synthesis using Real-Time PCR, the expression of the gene was investigated.

Results: 74% of adenocarcinoma cases were in T-categories of lung cancer and 25% of patients were in grade IIIa. Patients with T3 stage had four samples, 2 of which were adenocarcinoma and other 2 samples being SCC and their age ranged from 55 to 62 years old. Three patients were in the T1 category, of which 100% had adenocarcinoma. The results showed that expression of PD-L2 gene was increased 5.45 fold among patients with NSCLC-type lung cancer compared to those with normal condition.

Conclusion: PD-L2 expression detection methods, including the detection of mRNA expression by using Real-Time PCR and the use of multiple systems for detecting PD-L2 expression with cell type and in association with other immune markers, can make a deeper understanding of PD-L2 as a biomarker and help to diagnose lung tumors of the NSCLC type. In our studies, it was found that expression of PD-L2 gene in cancer patients is higher than normal conditions.