Growth suppression of four cancer cells by hyperbaric nitrous oxide and methotrexate

Abstract

BackgroundNitrous oxide concentration is easily controlled by respiratory ventilation. It suppresses bone marrow via the inhibition of thymidylate synthesis. The aim of this work was to determine the optimal pressure and exposure duration of nitrous oxide, as well as methotrexate concentration that maximizes the suppression of 4 cancer cells: CCRF-CEM, K562, A549 and MDA-MB-231.MethodsEach cancer cell was cultured in a hyperbaric chamber at 1, 2 and 3 atmosphere of 74% nitrous oxide for 24, 48, and 72 hours at 0, 0.3, 0.7, 1, 2, 5 and 10 µM methotrexate (MTX), respectively. The results were expressed in the ratio of the number of cancer cells cultured under specific conditions (S cells) to that under normal conditions (N cells).ResultsThe S/N ratio of CCRF-CEM cells was 87.4% in 24-hour culture, 95.0% in 48-hour culture and 115.9% in 72-hour culture (P < 0.05). The S/N ratio of K562 cells was 103.6% at 1 atm, 102.4% at 2 atm and 115.6% at 3 atm (P < 0.05). The S/N ratio of A549 cells was 94.3% at 1 atm, 94.1% at 2 atm, 99.3% at 3 atm, 96.2% in 24-hour culture, 99.2% in 48-hour culture and 99.3% in 72-hour culture (P > 0.05). However, the S/N ratio of MDA-MB 231 cells was 66.9% in 24-hour culture, 83.1% in 48 hour culture and 87.8% in 72-hour culture (P < 0.05).ConclusionsOnly the growth of the MDA-MB-231 cells was significantly reduced after a longer exposure time to nitrous oxide, but those of the other cells were not.

The history of nitrous oxide. Should it still be used in pediatric medicine? (Part II)

“…Also the growth suppression of leukemic cells by hyperbaric nitrous oxide for a longer time has been studied [33]. An in vitro study with 4 cancer cell-lines (CCRF-CEM, K562, A549 and MDA-MB-231) demonstrated that administration of N 2 O at hyperbaric pressures made not difference [34].…”