Evaluation of the Cellular Effects of miR-30d-3p in A549 Cells Under Normoxic and Hypoxic Conditions

Introduction/Objective: The tumor suppressor miR-30d-3p is upregulated under hypoxic conditions, suggesting a functional role in tumor progression. This study aimed to determine the association between miR-30d-3p and junction-mediating and regulatory protein (JMY) and to examine their effects on proliferation, cell cycle, migration, and apoptosis in A549 cells cultured under both normoxic and hypoxic conditions. Methods: Cell proliferation and migration were analyzed using real-time cell analysis (RTCA). Flow cytometry was employed to assess cell-cycle distribution and apoptosis. The expression levels of miR-30d-3p, JMY, and related genes under different oxygen conditions were determined using quantitative RT-PCR. Results: Under hypoxia, miR-30d-3p expression increased 6.1-fold. JMY mRNA expression also rose approximately twofold following miR-30d-3p inhibitor transfection under normoxia. The miR- 30d-3p mimic increased the G1 population (62% vs. 49.2% in controls) and reduced migration by 48.4% under normoxia, while also inducing apoptosis. Under hypoxia, the miR-30d-3p inhibitor caused a slight rise in sub-G1/G1 phases at 72 h and reduced proliferation by 56.9%. Discussion: miR-30d-3p exhibited oxygen-dependent effects, acting as a tumor suppressor under normoxia but showing altered behavior under hypoxia. Hypoxia-related HIF-1α stabilization and metabolic adaptation contributed to growth inhibition and modified cellular responses to miR-30d- 3p. Increased JMY levels following miR-30d-3p inhibition support a regulatory miR-30d- 3p/JMY/p53 axis influencing proliferation, cell cycle, and migration. Conclusion: These findings suggest that A549 cells are sensitive to changes in miR-30d-3p expression under normoxic and hypoxic conditions; however, its effects on cellular processes differ depending on oxygen availability. Thus, miR-30d-3p may represent a potential therapeutic target for non-small cell lung cancer (NSCLC) and could pave the way for innovative approaches to cancer diagnosis and treatment.