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First Evaluation of the Biologic Effectiveness Factors of Boron Neutron Capture Therapy (BNCT) in a Human Colon Carcinoma Cell Line

2010; Elsevier BV; Volume: 79; Issue: 1 Linguagem: Inglês

10.1016/j.ijrobp.2010.07.020

1879-355X

María Alejandra Dagrosa, Martín Crivello, Marina Perona, Silvia I. Thorp, Gustavo A. Santa Cruz, Emiliano C. C. Pozzi, Mariana Casal, Lisa Thomasz, R. L. Cabrini, Steven Kahl, Guillermo J. Juvenal, Mario A. Pisarev,

Nuclear Physics and Applications

Purpose DNA lesions produced by boron neutron capture therapy (BNCT) and those produced by gamma radiation in a colon carcinoma cell line were analyzed. We have also derived the relative biologic effectiveness factor (RBE) of the neutron beam of the RA-3- Argentine nuclear reactor, and the compound biologic effectiveness (CBE) values for p-boronophenylalanine ( 10 BPA) and for 2,4-bis (α,β-dihydroxyethyl)-deutero-porphyrin IX ( 10 BOPP). Methods and Materials Exponentially growing human colon carcinoma cells (ARO81-1) were distributed into the following groups: (1) BPA (10 ppm 10 B) + neutrons, (2) BOPP (10 ppm 10 B) + neutrons, (3) neutrons alone, and (4) gamma rays ( 60 Co source at 1 Gy/min dose-rate). Different irradiation times were used to obtain total absorbed doses between 0.3 and 5 Gy (±10%) (thermal neutrons flux=7.5 10 9 n/cm 2 sec). Results The frequency of micronucleated binucleated cells and the number of micronuclei per micronucleated binucleated cells showed a dose-dependent increase until approximately 2 Gy. The response to gamma rays was significantly lower than the response to the other treatments ( p < 0.05). The irradiations with neutrons alone and neutrons + BOPP showed curves that did not differ significantly from, and showed less DNA damage than, irradiation with neutrons + BPA. A decrease in the surviving fraction measured by 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolium bromide (MTT) assay as a function of the absorbed dose was observed for all the treatments. The RBE and CBE factors calculated from cytokinesis block micronucleus (CBMN) and MTT assays were, respectively, the following: beam RBE: 4.4 ± 1.1 and 2.4 ± 0.6; CBE for BOPP: 8.0 ± 2.2 and 2.0 ± 1; CBE for BPA: 19.6 ± 3.7 and 3.5 ± 1.3. Conclusions BNCT and gamma irradiations showed different genotoxic patterns. To our knowledge, these values represent the first experimental ones obtained for the RA-3 in a biologic model and could be useful for future experimental studies for the application of BNCT to colon carcinoma.