In vitro Studies of cellular response to boron neutron capture therapy (BNCT) in thyroid carcinoma.

RODRIGUEZ , C; CARPANO, M; PERONA, M; THORP, S; CUROTTO, P; POZZI, E; CASAL, M; JUVENAL , G; PISAREV , M; DAGROSA, MA

Tsukuba

Congreso; 15TH International Congress on Neutron Capture Therapy; 2012

Background: We have previously started to study the mechanisms of DNA damage and repair induced by BNCT in thyroid carcinoma some years ago. We have shown different genotoxic patterns for tumor cells irradiated with gamma rays, neutrons alone or neutrons plus different compounds, boronophenylalanine (BPA) or a,b-dihydroxyethyl)-deutero-porphyrin IX (BOPP). The DNA damage and the expression of Ku70 (protein repair of the non homologous end-joining via NHE J) was higher in the cells irradiated with neutrons in presence of 10BPA than in the other groups. In the present study we analyzed the expression of Ku 70, Rad 51 and Rad 54 components of non homologous end-joing (NHEJ) and homologous recombination repair (HRR) pathways, respectively, induced by BNCT in human cells of thyroid carcinoma. Methods: A human cell line of follicular thyroid carcinoma (WRO) in growth exponential phase was distributed into the following groups: 1) BPA boronophenylalanine (10 µg10B/mL) + neutrons; 2) Neutron beam alone; 3) Gamma rays. A control group for each treatment was added. The cells were irradiated in the thermal column facility of the RA-3 reactor (flux= 1.1010 n/cm2 sec) or with a source of 60Co. The irradiations were performed during different lapses in order to obtain a total physical doses between 1-5 Gy (±10%). Cell survival was evaluated with the 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazoliumbromide (MTT) and the mRNA expressions of Ku70, Rad 51 and Rad 54 were analysed by reverse transcription-polymerase chain reaction (RT-PCR) at different times post irradiation (2, 4, 6, 24 and 48 h). Results: The neutron irradiation of the cells in the presence of 10B showed a decrease in the cell viability. This effect was greater in cells incubated with BPA. The expression of Rad 51 increased at 2 h post-irradiation and it lasted until 6 h only in the neutron and neutron + BPA groups (p