title: Topoisomerase I levels in the NCI-60 cancer cell line panel determined by validated ELISA and microarray analysis and correlation with indenoisoquinoline sensitivity.
abstract: Topoisomerase I (Top1) is a proven target for cancer therapeutics, and the level of Top1 in tumors has been used as a biomarker for chemotherapeutic efficacy. In this study, we report the development and validation of a two-site enzyme chemiluminescent immunoassay for Top1, which we used to measure Top1 levels in the NCI-60 cancer cell line panel. Top1 levels ranged from 0.9 to 9.8 ng/mL/microg protein extract in these cell lines. Levels varied both within and between cancer types but were generally highest in colon cancer and leukemia cell lines and lowest in central nervous system and renal cancer cell lines. Top1 mRNA levels in the NCI-60 cell lines were also measured by microarray; mRNA values generally showed a good correlation with protein levels (Pearson correlation = 0.8). When these expression levels were compared with the activity of the indenoisoquinoline class of Top1 inhibitors across the NCI-60 cell panel, low levels of Top1 were associated with increased resistance to these drugs. The results of our studies indicate that our Top1 assay can be used to quantify Top1 levels in untreated cells as well as cells treated with Top1 inhibitors and that the assay has the potential to be adapted for use in predicting clinical response to Top1-active antineoplastic agents.
authors: Laboratory of Human Toxicology and Pharmacology, Applied/Developmental Research Support Directorate, Science Applications International Corporation-Frederick Inc, National Cancer Institute-Frederick, Frederick, MD 21702, USA.
authors: Thomas D
authors: TD
authors: Pfister
authors: William C
authors: WC
authors: Reinhold
authors: Keli
authors: K
authors: Agama
authors: Shalu
authors: S
authors: Gupta
authors: Sonny A
authors: SA
authors: Khin
authors: Robert J
authors: RJ
authors: Kinders
authors: Ralph E
authors: RE
authors: Parchment
authors: Joseph E
authors: JE
authors: Tomaszewski
authors: James H
authors: JH
authors: Doroshow
authors: Yves
authors: Y
authors: Pommier
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D045744:Cell Line, Tumor / Q000737:chemistry; D049109:Cell Proliferation / Q000187:drug effects; D004264:DNA Topoisomerases, Type I / Q000032:analysis* / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007192:Indenes / Q000737:chemistry; D007546:Isoquinolines / Q000737:chemistry*; D008163:Luminescent Measurements; D046228:Microarray Analysis; D054547:National Cancer Institute (U.S.); D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014481:United States
chemical_list: D000970:Antineoplastic Agents; D007192:Indenes; D007546:Isoquinolines; D012333:RNA, Messenger; D004264:DNA Topoisomerases, Type I