ХАРАКТЕРИСТИКА МУТАЦИОННОГО ЛАНДШАФТА ПЛОСКОКЛЕТОЧНОГО РАКА ЛЁГКОГО С ВЫСОКИМ РИСКОМ ГЕМАТОГЕННОГО МЕТАСТАЗИРОВАНИЯ

Lung cancer is one of the most important medical and socio-economic problems in most developed countries in the world due to its leading position in cancer incidence and mortality [1]. The main causes of high mortality in patients with lung cancer are the late detection of the tumor and the high incidence of distant metastasis (DM) [2]. However, even with timely diagnosis, the five-year survival of patients with lung cancer, mainly non-small cell lung cancer (NSCLC), is slightly more than 50% due to the high incidence of DM [3]. The development of approaches to predict the metastasis risk in NSCLC patients is important for improving disease outcome. It is known that lung cancer is preceded by morphological changes in the bronchial epithelium. The development of lung squamous cell cancer (LUSC) includes the following premalignant changes: basal cell hyperplasia (BCH), squamous metaplasia, grade I-III dysplasia and carcinoma in situ [4]. In previous studies, the researchers of the Tomsk Cancer Research Institute revealed that DM are more often observed in the NSCLC patients with “isolated” BCH (iBCH) in small bronchi at distance from the primary tumor [5]. At the moment, the mechanisms of this association are not understood. Thus, this study was aimed to assess the mutational landscape of NSCLC associated with isolated BCH. The study included 10 patients (48 to 77 years old) with LUSC divided into three groups: 1) patients with iBCH and DM; 2) patients with iBCH but without DM; and 3) patients without premalignant bronchial lesions and DM. Premalignant lesions were analyzed in hematoxylin-eosin-stained sections of formalin-fixed paraffin-embedded samples of small bronchi distant (3-5 cm) from the tumor. DNA from fresh frozen samples of lung tumor and peripheral blood was isolated by the DNeasy Blood & Tissue Kit (Qiagen, USA). DNA libraries were prepared using the SureSelect XT v. 7.0 (Agilent, USA). The size and quantity of DNA samples and libraries was assessed using Qubit 4.0 (ThermoFisher Scientific, USA) and 4150 Tape Station (Agilent, USA). Whole-exome sequencing was perfomed on a NextSeq 500 (Illumina). The data was analyzed using GATK, Mutect2, ANNOVAR and Enrichr instruments. The study showed that the number of mutated genes is different in the LUSC patients depending on the presence of iBCH and DM. The patients with iBCH and DM demonstrated mutations in 1013 genes , among which 902 genes were specific. In the patients with iBCH but without D, alterations were found in 464 genes (376 specific genes). The patients without premalignant lesions and DM showed mutations in 286 genes (228 specific genes). Interestingly, in patients with iBCH, mutations were 1.8 times more in metastatic tumors than in non-metastatic tumors. This result probably indirectly indicates that the presence of iBCH is not an absolute prognostic factor for developing DM. Differences between the studied groups of LUSC patients were also observed in the number of cancer driver genes. The largest number of drivers, particularly TP53, ARID1B, RB1, CDH10, FLT4, KEAP1, PTEN, etc., was detected in patients with iBCH and DM. In addition, in these cases, mutations were more often found in genes encoding cell adhesion proteins (CDH8, CDH9, CDH10, CDH20, CD177, ITGAL, TENM3, SDK1, SDK2, SELP, PTPRT, PTPRD, PTPRM, PCDHB6, PCDHB14, PCDHB9, PCDHB2, PCDHB5, REG3A, and PLXNB2) and involved in carcinogenesis signaling pathways (TP53, RB1, MMP1, MMP2, EGFR, and RAF1). It is important to note that mutations in the tumor-suppressor gene TP53 were found in all patients with iBCH and DM. Thus, LUSC patients with iBCH in the bronchial epithelium at a distance from the primary tumor and DM show a highly mutable phenotype. Probably, these results explain the mechanism of the association between iBCH and DM in patients with NSCLC.   This study was supported by the Russian Science Foundation (grant #20-75-10060).