OBJECTIVE: It was tested as to why low-dose methotrexate (MTX) effective against rheumatoid arthritis poses considerable health risk at higher doses. METHODS: The tumorigenic potential of My1/De blast cells was followed by cytology and by the kinetics of (18)FDG uptake. The toxicity of MTX on chromatin condensation was compared to predictive normal intermediates of chromosome condensation in control cells. RESULTS: MTX below 0.1 µg/ml did not cause visible changes in interphase chromatin structure. At its lowest toxic concentration (0.1 µg/ml) chromatin margination was confined to the outer edge of the nucleus. Between 0.1 and 5 µg/ml concentrations apoptotic chromatin shrinkage correlated with the dose of MTX. Apoptosis was exerted in early S phase excluding the mitotic effect. At higher MTX concentrations (>10 µg/ml) necrotic disruption and expansion took place. The lowest necrotic concentration (10 µg/ml) was close to highest apoptotic MTX concentration (5 µg/ml). CONCLUSIONS: The switch from apoptosis to inflammatory necrosis taking place within a narrow concentration range supports the notion of a narrow therapeutic spectrum. Chromatin changes are early markers of genotoxicity at much lower concentrations than citogenetic changes in properly chosen sensitive cells.
OBJECTIVE: It was tested as to why low-dose methotrexate (MTX) effective against rheumatoid arthritis poses considerable health risk at higher doses. METHODS: The tumorigenic potential of My1/De blast cells was followed by cytology and by the kinetics of (18)FDG uptake. The toxicity of MTX on chromatin condensation was compared to predictive normal intermediates of chromosome condensation in control cells. RESULTS:MTX below 0.1 µg/ml did not cause visible changes in interphase chromatin structure. At its lowest toxic concentration (0.1 µg/ml) chromatin margination was confined to the outer edge of the nucleus. Between 0.1 and 5 µg/ml concentrations apoptotic chromatin shrinkage correlated with the dose of MTX. Apoptosis was exerted in early S phase excluding the mitotic effect. At higher MTX concentrations (>10 µg/ml) necrotic disruption and expansion took place. The lowest necrotic concentration (10 µg/ml) was close to highest apoptotic MTX concentration (5 µg/ml). CONCLUSIONS: The switch from apoptosis to inflammatory necrosis taking place within a narrow concentration range supports the notion of a narrow therapeutic spectrum. Chromatin changes are early markers of genotoxicity at much lower concentrations than citogenetic changes in properly chosen sensitive cells.
Authors: Isabella Lima Arrais Ribeiro; Rebecca Rhuanny Tolentino Limeira; Ricardo Dias de Castro; Paulo Rogério Ferreti Bonan; Ana Maria Gondim Valença Journal: Int J Environ Res Public Health Date: 2017-11-28 Impact factor: 3.390
Authors: Syed Shoeb Razvi; Hani Choudhry; Mohammed Nihal Hasan; Mohammed A Hassan; Said Salama Moselhy; Khalid Omer Abualnaja; Mazin A Zamzami; Taha Abduallah Kumosani; Abdulrahman Labeed Al-Malki; Majed A Halwani; Abdulkhaleg Ibrahim; Ali Hamiche; Christian Bronner; Tadao Asami; Mahmoud Alhosin Journal: Epigenet Insights Date: 2018-11-27