Chlorpyrifos stimulates expression of vitamin D 3 receptor in skin cells irradiated with UVB.

Skin, the organ responsible for vitamin D synthesis, is fully exposed to many xenobiotics, e.g. polycyclic aromatic hydrocarbons and pesticides. A broad spectrum organophosphorus insecticides (OP's), such as chlorpyrifos (CPS), are commonly used in agriculture and to control domestic insects. Thus, the aim of this study was to investigate the effect of chlorpyrifos, on the expression of vitamin D3 receptor (VDR) in human keratinocytes cell line HaCaT and fibroblasts cell line BJ. The impact of CPS and UVB radiation on cell viability were examined by Neutral Red assay. The effect of CPS on VDR expression was evaluated by RT-qPCR and flow cytometry (FC). The presented study demonstrated that exposure to CPS and UVB significantly affects the viability of HaCaT and BJ cells lines. Results also revealed that exposure to CPS induced the expression at mRNA and protein level of VDR nuclear receptor in both cell lines exposed to UVB. In HaCaT incubated with 250 μM CPS and 15 mJ/cm2 UVB, the relative VDR expression was ∼2-fold higher; whereas in BJ incubated with 250 μM CPS and 20 mJ/cm2 , UVB was∼3-fold higher. Results from FC confirmed this result, as VDR expression increased by ~250% in HaCaT incubated with 250 μM CPS and 20 mJ/cm2 UVB, and in BJ incubated with 250 μM CPS, and 20 mJ/cm2 UVB cells VDR expression increased by ~190%, compared with control. It can therefore be concluded that OPs pesticide might interfere with vitamin D3 metabolism in skin cells.