The effect of polyamines in selected prophetic fruits on human lung adenocarcinoma cell line, A549

Abstract

Polyamines are vital in maintaining human health because they perform certain functions that are necessary for cell development. However, extensive intracellular polyamines may promote unwarranted cell proliferation and to a certain extent, stimulates cancer initiation. Therefore, this study aimed to investigate the polyamines deficient diet in chemoprevention strategy using selected fruits recommended by the prophet against human lung adenocarcinoma cells, A549. Five prophetic fruits were selected, including Phoenix dactylifera (ajwa dates), Beta vulgaris (beetroot), Ficus auriculata (fig), Ziziphus jujube (jujube) and Vitis vinifera (raisins). Initially, they were freeze dried and stored in -80°C until analysis. The polyamines in each selected prophetic fruit was quantified and classified by High Performance Liquid Chromatography (HPLC). Subsequently, their anti-proliferative effect on A549 cells growth was evaluated using MTT assay and Trypan blue exclusion assay. Protein content was measured using Lowry assay. The activity of genes that regulate polyamine metabolic pathway particularly ornithine decarboxylase (ODC) and spermine/spermidine (N1)-acetyltransferase (SSAT) was elucidated using qPCR. Finally, cell cycle profile and apoptosis assay were conducted with flow cytometer, while caspase assay was done using colorimetric method. It has been found that jujube showed the highest polyamines concentration (219.6 ±4.4 nmoles/ml) while fig was the lowest (39.3±3.0 nmoles/ml). MTT assay suggested IC50 of fruits recommended by the prophet was ranged from 15 mg/ml to 30 mg/ml. All selected prophetic fruits showed anti-proliferative effect against A549 cells. Protein content was significantly lower after 72 h of treatment with selected prophetic fruits, and total elimination of intracellular spermidine and spermine were observed in all treated A549 cells. The polyamines metabolism was found to be altered in which the intracellular polyamines depletion was mainly contributed by the downregulation of ODC in A549 cells treated with ajwa dates and jujube. Meanwhile, beetroot and fig induced the upregulation of SSAT. Cell cycle profile displayed significant cell cycle arrest at G2/M after 48 h of exposure to jujube and raisins. It is demonstrated that beetroot, fig, jujube and raisins induced apoptosis after 48 h exposure while ajwa dates might induced other type of cell death. Caspase assay revealed significant activation of caspase 3, 8 and 9 in beetroot treated cells while no caspase activation was identified in other prophetic fruits treated cells. Considering the classification of polyamines, the anti-proliferative effect and the type of cell death, it was concluded that fig, raisins and beetroot are the promising candidates for nutritional cancer therapy and preventive approaches for cancer.