Comparative studies of boronophenylalanine (BPA) uptake in three human cell lines of malignant melanoma.

CARPANO, M; DAGROSA, MA; NIEVAS, S; ROSSINI, AE; JUVENAL, G; PISAREV , M

Buenos Aires

Congreso; 14th International Congress of Neutron Capture Therapy; 2010

CNEA, UNSAM, ROFFO

Introduction: Melanoma is an aggressive tumor which can be controlled with the conventional treatments if its detection is early. However, when the tumor is advanced, the effectiveness of the usual therapies is poor. BNCT has been used for the treatment of melanoma in different countries around the world and the results are variable. Tumors from different patients with the same histological diagnosis can show varied responses to ionizing radiation. The aim of the present work was to study and compare the uptake of BPA and the time-dependence in three different human melanoma cell lines: MEL J, A375 and M8. As a second objective we analysed the effect of cyclic AMP, as a biochemical factor, on the BPA uptake. Materials and Methods: Three cell lines (MEL J; A375; M8) were grown in culture medium RPMI or DMEM/F12 which contains antibiotics and 10% bovine fetal serum. The cells were incubated with BPA (50 ppm 10B) during different times (0.5, 1, 2, 4 and 24 h). The intracellular boron content was quantified by ICP–OES. Results and Discussion: The uptake of BPA, as a function of time, was different for each cell line studied. MEL J showed a peak in the intracellular boron at 2 h, on the contrary A375 showed the higher boron concentration at 4 h. At 24 h saturation in the uptake of BPA was observed for MELJ and for A375 while M8 did not change the boron concentration during the different times. At 24 h the BPA average uptake ± SEM was 0.129 ± 0.02 µg B/106 cells for MELJ, 0.112 ± 0.005 µg B/106 cells for A375 and 0.041 ± 0.005 µg B/106 cells for M8. The ratios MELJ/M8 and A375/M8 were 3.14 and 2.73 respectively. On the other hand the analysis of 0.1 mM cyclic AMP on BPA uptake performed at different times showed that this factor increases significantly the boron content at 2 h (p<0.05). However this effect is reversed after 24 h. The three melanoma cell lines showed different patterns of BPA uptake being higher for two of them (MELJ y A375 vs. M8) and earlier for one of the three (MEL J). Also it was observed that cyclic AMP can increase the BPA uptake at 2 h. The reversion of the effect, observed at 24 h, could be explained by the intracellular degradation of cyclic AMP. These preliminary results suggest a new way for the application of BNCT based on the specific characteristics of each individual tumor and open a possibility for its optimization by increasing the boron concentration in the tumor.