Differential expression of DNA topoisomerase I gene between CPT-11 acquired-and native-resistant human pancreatic tumor cell lines: Detected by RNA PCR-based quantitation assay

Sachi Takeda, Takao Shimazoe, Keiki Sato, Yoshikazu Sugimoto, Takashi Tsuruo, Akira Kono

Research output: Contribution to journalArticle

32 Citations (Scopus)


RNA PCR quantitation method was developed to determine DNA Topoisomerase I(Topo I)-specific mRNA in order to study its gene expression in CPT-11 sensitive, acquired- or native-resistant human pancreatic tumor cell lines. The results were supported by Northern blotting and Western blotting analyses. Acquired-resistant cells have shown decreased levels of Topo I mRNA, compared with their parental cells. On the contrary, in the wild type cells no correlation was shown between sensitivity and gene expression. On the other specific Topo I activity of the native resistant cell lines was fairly lower than that of sensitive cell lines, suggesting that immunoreactive Tope I protein contains low levels of active form enzyme which could be targets of CPT-11 in these native-resistant ones. Finally, the different mechanisms might be operative between acquired- and native-resistant tumor cells.

Original languageEnglish
Pages (from-to)618-625
Number of pages8
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - 1992 Apr 30
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this