Protein arginine methyltransferase-5  Selective Inhibitor Enhances Therapeutic Effects of Cisplatin on Lung Cancer Cells

Abstract Background Lung cancer is the most common cancer globally. Protein arginine methyltransferase 5 (PRMT5) is identified to be involved in gene transcriptional regulation and cell division. PRMT5 is highly expressed in lung adenocarcinoma, hepatocellular carcinoma, and melanoma, raising evidence that PRMT5 might be involved in tumorigenesis. The aim of this study is to examine potential selective anti-neoplastic activity of PRMT5 inhibitor, Arginine methyltransferase inhibitor 1 (AMI-1) and cisplatin on lung adenocarcinoma. Methods Effect of AMI-1 on PRMT5 activity inhibition in lung adenocarcinoma cell line, A549, in response to standard chemotherapeutic agent, cisplatin, was assessed. Bioinformatic analyses were carried out to identify the prognostic value of PRMT5 and its major functional pathways in lung adenocarcinoma. Cell viability, PMRT5 protein levels, extent of cell migration, survival of cancer cells, and cell cycle progression and apoptosis were examined. Drug combination was also evaluated in human bronchial epithelial cells (HBEpC). Results Bioinformatics identified apoptosis, DNA damage, and cell cycle progression as the main PRMT5 associated functional pathways, and survival analysis linked the increased PRMT5 gene expression to worse overall survival. Combination treatment with 10 µM AMI-1 and of Cisplatin significantly reduced viable cell percentages. Cell cycle arrest in A549 cells was evident after AMI-1, which was reinforced after combination treatment. Apoptosis was observed after treatment with both drugs. Western blot analysis showed reduction in demethylation histone 4, a PRMT5- downstream target, after treatment with AMI-1 alone or in combination with cisplatin. While combination approach tackled lung cancer cell survival, it exhibited cytoprotective abilities on normal epithelial cells. Finally, treatment with both drugs led to a decreased cell migration rate. Conclusions This study highlights evidence of novel selective antitumor additive activity of AMI-1 in combination with cisplatin in lung adenocarcinoma cells. Survival of normal bronchial epithelial cells was not affected by using AMI-1.