| Co-Investigator(Kenkyū-buntansha) |
HARADA Shizuko National Institute of Infectious Diseases, Department of Virology I, Primary Investigator, ウイルス第一部, 主任研究官 (10218646)
UNNO Michiaki Tohoku University Hospital, Lecturer, 医学部附属病院, 講師 (70282043)
YAMORI Takao Japanease Foundation for Cancer Research, Cancer Chemotherapy Center, Molecular Pharmacology, Chairman, 癌化学療法センター・分子薬理部, 部長(研究職)
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| Research Abstract |
Background & Aims: One approach to the development of targeted cancer chemotherapy exploits increased uptake of the agent into neoplastic cells. In this scenario, higher concentrations of the agent in cancer cells are responsible for differential killing while the low concentration in normal human cells decreases side effects. The aim of this study is to isolate an organic anion transporter which in weakly in normal, but abundantly expressed in cancer cells, to deliver the anti-cancer drugs to the cells.
Methods: A human liver cDNA library was screened with LST-1 cDNA as a probe, Northern blot analyses were performed using the isolated cDNA (termed LST-2). A LST-2 specific antibody was raised and immunohistochemical analyses including immuno-electron microscopy were performed. Xenopus oocyte expression system was used for functional analysis. We also established a permanent cell line which consistently expresses LST-2 to examine the relationship between MTX uptake and sensitivity.
Results: The isolated cDNA, LST-2 has 79,7 % of overall homology wish human LST-1. LST-2 exclusively expressed in the liver under normal conditions and immunoreactivity was highest at the basolateral membrane of the hepatocytes around the central vein. Although its weak expression in the liver, LST-2 is abundantly expressed in the gastric, colon and pancreatic cancers, On she other hand, she LST-1 was only detected in a hepatic cell line, LST-2 transports methotrexate in a saturable and dose dependent manner Furthermore, introduction of the LST-2 gene into mammalian cells potentiates sensitivity to methotrexate.
Conclusion: LST-2 is one of the prime candidate molecule for determining methotrexate sensitivity and may be a good target on deliver anti-cancer drugs to the gastrointestinal cancers.
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