DCK is frequently inactivated in acquired gemcitabine-resistant human cancer cells

Yuriko Saiki, Yuki Yoshino, Hiroko Fujimura, Tatsuya Manabe, Yuki Kudo, Miki Shimada, Nariyasu Mano, Tomohiro Nakano, Yoonha Lee, Shinjiro Shimizu, Shinya Oba, Sho Fujiwara, Hideyuki Shimizu, Na Chen, Zhaleh Kashkouli Nezhad, Guo Jin, Shinichi Fukushige, Makoto Sunamura, Masaharu Ishida, Fuyuhiko MotoiShinichi Egawa, Michiaki Unno, Akira Horii

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83 Citations (Scopus)


Although gemcitabine is the most effective chemotherapeutic agent against pancreatic cancer, a growing concern is that a substantial number of patients acquire gemcitabine chemoresistance. To elucidate the mechanisms of acquisition of gemcitabine resistance, we developed gemcitabine-resistant cell lines from six human cancer cell lines; three pancreatic, one gastric, one colon, and one bile duct cancer. We first analyzed gemcitabine uptake using three paired parental and gemcitabine resistant pancreatic cancer cell lines (PK-1 and RPK-1, PK-9 and RPK-9, PK-59 and RPK-59) and found that uptake of gemcitabine was rapid. However, no DNA damage was induced in resistant cells. We further examined the microarray-based expression profiles of the cells to identify genes associated with gemcitabine resistance and found a remarkable reduction in the expression of deoxycytidine kinase (. DCK). DCK is a key enzyme that activates gemcitabine by phosphorylation. Genetic alterations and expression of . DCK were studied in these paired parental and derived gemcitabine-resistant cell lines, and inactivating mutations were found only in gemcitabine-resistant cell lines. Furthermore, siRNA-mediated knockdown of . DCK in the parental cell lines yielded gemcitabine resistance, and introduction of . DCK into gemcitabine-resistant cell lines invariably restored gemcitabine sensitivities. Mutation analyses were expanded to three other different paired cell lines, DLD-1 and RDLD-1 (colon cancer cell line), MKN-28 and RMKN-28 (gastric cancer cell line), and TFK-1 and RTFK -1 (cholangiocarcinoma cell line). We found inactivating mutations in RDLD-1 and RTFK-1 and decreased expression of . DCK in RMKN-28. These results indicate that the inactivation of . DCK is one of the crucial mechanisms in acquisition of gemcitabine resistance.

Original languageEnglish
Pages (from-to)98-104
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number1
Publication statusPublished - Apr 27 2012

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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