tretinoin and mipafox

Historically, only few chemicals have been identified as neurodevelopmental toxicants, however, concern remains, and has recently increased, based upon the association between chemical exposures and increased developmental disorders. Diminution in motor speed and latency has been reported in preschool children from agricultural communities. Organophosphorus compounds (OPs) are pesticides due to their acute insecticidal effects mediated by the inhibition of acetylcholinesterase, although other esterases as neuropathy target esterase (NTE) can also be inhibited. Other neurological and neurodevelopmental toxic effects with unknown targets have been reported after chronic exposure to OPs in vivo. We studied the initial stages of retinoic acid acid-triggered differentiation of pluripotent cells towards neural progenitors derived from human embryonal carcinoma stem cells to determine if neuropathic OP, mipafox, and non-neuropathic OP, paraoxon, are able to alter differentiation of neural precursor cells in vitro. Exposure to 1 µM paraoxon (non-cytotoxic concentrations) altered the expression of different genes involved in signaling pathways related to chromatin assembly and nucleosome integrity. Conversely, exposure to 5 µM mipafox, a known inhibitor of NTE activity, showed no significant changes on gene expression. We conclude that 1 µM paraoxon could affect the initial stage of in vitro neurodifferentiation possibly due to a teratogenic effect, while the absence of transcriptional alterations by mipafox exposure did not allow us to conclude a possible effect on neurodifferentiation pathways at the tested concentration.

Topics: Chromatin Assembly and Disassembly; Embryonal Carcinoma Stem Cells; Genome, Human; Histones; Humans; Insecticides; Isoflurophate; Neurogenesis; Neurons; Nucleosomes; Paraoxon; Phenotype; Tretinoin

Neuropathy target esterase (NTE) is inhibited and aged by organophosphorus compounds that induce delayed neuropathy in human and some sensitive animals. NTE has been proposed to play a role in neurite outgrowth and process elongation during neurodifferentiation. However, to date, there is no direct evidence of the relevance of NTE in neurodifferentiation under physiological conditions. In this study, we have investigated a possible role for NTE in the all-trans retinoic acid-induced differentiation of neuroblastoma cells. The functional inactivation of NTE by RNA interference indicated that reduction of NTE does not affect process outgrowth or differentiation of the cells, although moderate expression of NTE by expression of the NTE esterase domain accelerates the elongation of neurite processes. Mipafox, a neurotoxic organophosphate, was shown to block process outgrowth and differentiation in cells that have lowered NTE activity due to RNA interference, suggesting that mipafox may interact with other molecules to exert its effect in this context.

Topics: Acetylcholinesterase; Animals; Antineoplastic Agents; Carboxylic Ester Hydrolases; Cell Differentiation; Cell Line, Tumor; Cholinesterase Inhibitors; Gene Silencing; Humans; Isoflurophate; Neuroblastoma; Neurons; Paraoxon; RNA Interference; Tretinoin