MiR-16-1-3p and miR-16-2-3p Overexpression Confers Tumor Suppressive and Antimetastatic Properties in Radioresistant A549 Non-Small Cell Lung Cancer Cells

Purpose: Lung cancer is the leading cause of death worldwide, with non-small cell lung cancer (NSCLC) accounting for 85 % of all lung cancers. Combined chemoradiotherapy is one of options in the treatment of patients with inoperable NSCLC. However, the prognosis of NSCLC remains unsatisfactory due to the development of radio- and chemo-resistance of cancer cells. This study aimed to investigate how the overexpression of miR-16, miR-16-1-3p, and miR-16-2-3p influences clonogenic survival, migration, and sensitivity to cisplatin in both radiosensitive and radioresistant non-small cell lung cancer (NSCLC) cells.

Material and methods: This study involved the application of single proton beam irradiation to A549 NSCLC cells, resulting in the emergence of a subline of resilient radioresistant daughter cells, designated as A549IR. To explore the functional role of the miR-16, miR-16-1-3p, and miR-16-2-3p in NSCLC, we overexpressed the “leader” miR-16 as well as the “passenger” miR-16-1-3p and miR-16-2-3p strands in both the parental A549 and their radioresistant variant, A549IR cells. The impact of microRNA overexpression on cell viability was evaluated through a clonogenic assay. Additionally, cisplatin sensitivity was measured by calculating the total mass of surviving cells via the sulforhodamine B method. Furthermore, the capacity for cell migration and invasion was investigated using Boyden chambers.

Results: Overexpressing miR-16, miR-16-1-3p, and miR-16-2-3p significantly reduced the ability of A549 and radioresistant A549IR NSCLC cells to survive, clone, migrate, and invade, compared to cells with normal levels of these microRNAs. Moreover, the stable overexpression of these microRNAs markedly enhanced the sensitivity of A549 and A549IR cells to the cytotoxic effects of cisplatin, allowing for a nearly threefold reduction in the concentration needed to achieve 50 % cell death.

Conclusion: An increase in the expression of “passenger” miR-16-1-3p and miR-16-2-3p, as well as the “leader” miR-16, exhibits a robust tumor-suppressive and cisplatin-sensitizing activities in both the radiation-sensitive parental and the radiation-resistant daughter cells in the human NSCLC A549 lineage.