MECHANISM OF 2´-NITROFLAVONE AND SAFINGOL ANTITUMOR SYNERGISTIC COMBINATION IN MAMMARY CANCER CELLS

JUAN MANUEL ANSELMI RELATS,; LEONOR ROGUIN,; MARIEL MARDER; JULIETA MARINO; VIVIANA BLANK

Congreso; REUNIÓN ANUAL DE SOCIEDADES DE BIOCIENCIAS; 2022

Sphingosine kinase 1 (SphK1), a lipid kinase overexpressed in some mammary tumorcells, regulates the balance between proapoptotic ceramides and prosurvival sphingosine-1-phosphate. Furthermore, SphK1 inhibitors prevent catabolism of ceramides, contributingto tumor cell death. It has been reported that certain flavonoids exert antitumor activitythrough an increment in ceramide levels. Previously, we demonstrated that the syntheticflavonoid 2´-nitroflavone (2NF) and the SphK1 inhibitor safingol synergistically inhibited cellproliferation and induced apoptosis in LM3 murine mammary tumor cells. In this work, weexamined the modulation of JNK and ERK 1/2 MAPK transduction pathways. Resultsshowed that after 1h of incubation with both compounds, the levels of p-JNK and p-ERK1/2 MAPKs were significantly increased (2,3 ± 0,3 fold, p<0,05; 1,5 ± 0,1 fold, p<0,01,respectively). Moreover, the antiproliferative effect of the combination was reverted whencells were preincubated with JNK SP600125 or ERK1/2 PD98059 inhibitors. Additionally,we studied the antitumor efficacy of 2NF combined with safingol in human mammaryMDA-MB-453 cancer cells and also found a synergistic reduction of cell growth aftertreatment with 5 µM 2NF and 0,625 µM safingol. Analysis by Compusyn software showedCombination Index values of 0,63 ± 0,08 (48 h) and 0,73 ± 0,06 (72 h). Ethidium bromideand acridine orange staining revealed that safingol potentiated the apoptosis induced by2NF in these cells. When we evaluated the expression of Bax proapoptotic protein, resultsobtained by Western blot showed a 3,6 ± 0,4 fold increment after cell incubation with both2NF and safingol for 24 h (p<0.001). Taken together, these results demonstrated that thecombination of 2NF and safingol induced a synergistic antitumor effect in mammarycancer cells, probably mediated by the activation of JNK and ERK1/2 MAPKs pathways.