Antiproliferative effect of the combination of 2´nitroflavone and safingol in mammary tumor cells?

GENTILCORE FLORENCIA; MARDER MARIEL; ROGUIN LEONOR; MARINO JULIETA; BLANK VIVIANA

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

In a previous work, we have demonstrated that the synthetic flavonoid 2´nitroflavone (2´NF), obtained in our lab, inhibited tumor growth by inducing apoptosis in vitro and in vivo in the murine mammary tumor model LM3. Some authors have proved that certain flavonoids induce apoptosis through an increase in the amount of ceramides. It has also been reported that the sphingosine kinase inhibitor safingol prevents ceramide catabolism, contributing to tumor cell death. Based on these results, in the search of new drug combinations that enhance the effect of each drug, we decided to explore the antiproliferative effect of the combination of 2´NF and safingol in LM3 cells. Cells were incubated with different concentrations of 2´NF and safingol alone or combined for 48 or 72h. IC50 values were 21±3 μM (48h) and 8±1 μM (72h) for 2´NF, and 1.4±0.5 μM (48h) and 1.1±0.4 μM (72h) for safingol. Proliferation of NMuMG normal murine mammary cells was not affected after 72h of incubation with concentrations of 50 μM (2´NF) or 5 μM (safingol). In order to quantitatively characterize the interaction between 2´NF and safingol, dose-effect curves were analyzed by Compusyn software. Results obtained showed that combination indexes were 0.72±0.06 (48h) and 0.71±0.01 (72h), indicative of synergism, in cells incubated with 5 μM of 2´NF and 0.6 μM of safingol. Additionally, when cells were treated with the same drug combination for 24h, an increase in the number of cells with apoptotic characteristics was observed by fluorescence microscopy after ethidium bromide and acridine orange staining. Furthermore, an increment of hypodiploid cells was detected by flow cytometry analysis. In conclusion, we demonstrated that a specific combination of safingol and 2´NF synergistically inhibited mammary tumor cell proliferation. This finding encourage us to study the molecular mechanisms involved in this effect and to consider this drug combination as a potential therapy for mammary cancer treatment.