Abstract
Background: [Methyl-3H]-choline is a promising new positron emission tomography (PET) agent used for cancer imaging whose mechanism has still not fully been elucidated. In this study, whether [methyl-3H]-choline determined by measuring the activity of choline kinase (ChoK) and phospholipase D (PLD) in rapidly proliferating and confluent breast cancer MCF-7 cells is related to cell proliferation or not was investigated. Materials and Methods: The activity of ChoK and PLD were determined using ion exchange chromatography and transphosphatidylation assay respectively. Results: [Methyl-3H]-PCho content expressed as pmol mg-1 protein-1 min-1 (n=6) was significantly higher in the exponentially growing (484.04±20.23) compared with confluent (70.35±9.83) cells using Student's t-test (p<0.001). Moreover, PLD activity expressed as the mean (n=6) (disintegration per minute (d.p.m.)/μg protein±SD (mean S phase ±SD)) showed significantly higher (p<0.001) activity in the exponentially growing cells (196.39±2.21 d.p.m./μg protein (39.69±4.00%)) compared with confluent cells (99.10±1.35 d.p.m./μg protein (9.33±0.82%)). Conclusion: This study indicates that the major water-soluble choline metabolite was phosphocholine (PCho) as a consequence of increased ChoK and PLD activity in the exponentially growing cells compared to confluent cells.
Footnotes
- Received October 27, 2006.
- Revision received January 22, 2007.
- Accepted January 30, 2007.
- Copyright© 2007 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved