Expression of AHR-regulated and PD-L1-regulated microRNAs in squamous cell lung cancer

Abstract

Introduction. Despite modern advances in research into the risk of development, immunological control and treatment options for lung cancer (LC), it is the leading cause of death from cancer. Tobacco smoking remains the predominant risk factor for the development of lung cancer, especially one of its aggressive subtypes, squamous cell lung cancer (SCLC). Benzo[a]pyrene, a component of cigarette smoke, promotes the activation of the aryl-hydrocarbon receptor (AhR). AhR regulates the expression of many oncogenes, including PD-L1, the positive status of which is an indication for immunotherapy, one of the main treatment strategies for SCLC. However, to improve the effectiveness of treatment of SCLC, further search for new diagnostic, prognostic and therapeutic markers is necessary. MicroRNAs (miRs), which are highly stable and present in biological fluids, can act as such markers.Objective. Search for microRNAs that could potentially serve as diagnostic markers or therapeutic targets for SCLC. For this purpose, microRNAs were selected whose promoter regions contain AhR binding sites or whose target is PD-L1.Materials and methods. A biocollection of tumor and conditionally normal lung tissue samples (n = 40) was collected at the thoracic department of the Novosibirsk Clinical Oncology Dispensary. The relative levels of selected miRNAs were examined using real-time reverse transcription-PCR (RT-PCR) technique.Results. The levels of miR-342 and miR-181a in SCLC tissues were reduced by 3 times relative to conditionally normal tissue. The expression of miR-181a and miR-155 is associated with tumor size (lower levels in tumors larger than 3 cm) and the presence of metastases in the lymph nodes (3- and 2-fold lower levels in cases with metastases). The level of miR-146a decreased by 3 times in patients with metastatic lesions of lymph nodes. A significant relationship between the levels of miR-93, miR-181a and miR-155 and the expression status of PD-L1 was also found.Conclusions. The expression profile of miR-146a, miR-93, miR-181a and miR-155 differs in SCLC patients depending on PD-L1 status and the presence or absence of lymph node metastases.