Although chemotherapy and radiation resulted in a high cure rate in classical Hodgkin’s lymphoma (cHL), the treatment is associated with long-term side effects including cardiopulmonary toxicities and development of secondary neoplasms. To mitigate these concerns, research focused on the development and discovery of new therapeutic approaches.
Luteolin (LUT), a flavonoid that naturally occurs in fruits,and vegetables, has attracted much attention for its role in the treatment of human ailments and its anticancer activities. To date however, there is no study on the effect of LUT on malignant lymphomas. Therefore, the goal of this study was to investigate the potential anti-cancer effects of LUT on cHL.
Cell growth was assessed with water-soluble tetrazolium 1 (WST-1) cell proliferation assay and automated hemocytometry on trypan blue-exclusion assay. Cell death was investigated with acridine orange(AO)/ethidium bromide (EtBr) live-dead assay, propidium iodide (PI) flow cytometry, and Annexin-V-PI microscopy. Caspase activation was studied using CellEvent Caspase-3/7 Green detection reagent. High resolution immunofluorescence microscopy was used to detect cleaved-PARP-1.
The cell growth assays showed dose-dependent suppression growth of cHL cell lines KMH2 and L428, cellular models of mix cellularity (MC) and nodular sclerosis (NS) cHL subtypes, respectively, 48 hours after treatment. However, LUT, at higher doses (40µM and higher), induced cell death only in KMH2, as revealed by AO/EtBr assay and Annexin-V-PI microscopy and PI flow cytometry. Caspase3/7 detection dye revealed significantly higher levels of caspase3/7-postive cells in LUT (40µM)-treated KMH2 cells. In addition, high-resolution immunofluorescent imaging of LUT (40µM)-treated KMH2 revealed nuclear cleaved-PARP-1, in regions presumed to be where PARP-1 interacts with DNA. PARP-1 is a DNA repair enzyme and cellular substrate of caspases 3/7.
These results suggest caspase-activated cell death is a putative mechanisms by which LUT reduces growth of MC-cHL.
