Intracellular reactions affecting 2-amino-4-([(11)C]methylthio)butyric acid ([(11)C]methionine) response to carbon ion radiotherapy in C10 glioma cells.
OBJECTIVE
The response of 2-amino-4-([(14)C]methylthio)butyric acid ([(14)C]Met) uptake and [(125)I]3-iodo-alpha-methyl-l-tyrosine ([(125)I]IMT) uptake to radiotherapy of C10 glioma cells was compared to elucidate the intracellular reactions that affect the response of 2-amino-4-([(11)C]methylthio)butyric acid ([(11)C]Met) uptake to radiotherapy.


METHODS
After irradiation of cultured (3 Gy) or xenografted C10 glioma cells (25 Gy) using a carbon ion beam, the accumulation of [(14)C]Met and [(125)I]IMT in the tumors was investigated. The radiometabolites in xenografted tumors after radiotherapy were analyzed by size-exclusion HPLC.


RESULTS
[(14)C]Met provided earlier responses to the carbon ion beam irradiation than [(125)I]IMT in both cultured and xenografted tumors. While [(125)I]IMT remained intact in xenografted tumor before and after irradiation, the radioactivity derived from [(14)C]Met was observed both in high molecular fractions and intact fractions, and the former decreased after irradiation.


CONCLUSIONS
The earlier response of [(11)C]Met uptake to tumor radiotherapy could be attributable to the decline in the intracellular energy-dependent reactions of tumors due to radiotherapy.
Uehara
Tomoya
T
Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan. tuehara@p.chiba-u.ac.jp
Nakagawa
Misuzu
M
Takai
Nobuhiko
N
Koike
Sachiko
S
Furusawa
Yoshiya
Y
Ando
Kouichi
K
Kawai
Keiichi
K
Akizawa
Hiromichi
H
Irie
Toshiaki
T
Arano
Yasushi
Y
D002250:Carbon Radioisotopes / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D005910:Glioma / Q000378:metabolism* / Q000532:radiotherapy*; D020450:Heavy Ions; D006801:Humans; D008657:Metabolic Clearance Rate / Q000528:radiation effects; D008715:Methionine / Q000493:pharmacokinetics*; D008781:Methyltyrosines / Q000493:pharmacokinetics*; D011829:Radiation Dosage; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics / Q000627:therapeutic use
D002250:Carbon Radioisotopes; D008781:Methyltyrosines; D019275:Radiopharmaceuticals; C030855:3-iodo-alpha-methyltyrosine; D008715:Methionine