Apoptosis of HeLa and CaSki cell lines incubated with All-trans retinoid acid.

The aim of the study was to evaluate the concentrations of a soluble form of APO-1/Fas antigen (sFas, CD95) and a soluble Ligand for APO-1/Fas antigen (sCD95L, sFasL) in supernatants from CaSki and HeLa cell line cultures after the incubation with All-trans-retinoic acid. HPV-16 and HPV18 - positive cell lines were cultivated with All-trans-retinoic acid in concentrations of 1 x 10(-6) M/L and 1 x 10(-8) M/L. The cultures were incubated for 24 hours. Control culture with 3 microl of dimethyl-sulphoxide (DMSO) was incubated under identical conditions. The concentrations of soluble APO-1/Fas antigen and Fas Ligand in cell culture supernatants were estimated using immunoenzymatic methods. The obtained results showed significant decrease of concentrations of soluble APO-1/Fas antigen in supernatants from HeLa cell lines incubated with retinol in comparison with the control culture. Moreover, the concentrations of soluble Ligand for APO-1/Fas antigen in the supernatants of CaSki and HeLa cell lines were significantly lower in the culture incubated with All-trans retinoid acid when compared to the control culture. Higher concentrations of soluble APO-1/Fas antigen in supernatants from HeLa cell line without retinol may constitute a protective mechanism of the cells infected with the virus before undergoing Fas/FasL-dependent apoptosis. Lower concentrations of soluble APO-1/Fas antigen and soluble Ligand for APO-1/Fas in the supernatants from CaSki and HeLa cell cultures incubated with retinol suggest that retinoids can decrease the synthesis of soluble APO-1//Fas and soluble FasL in HPV-16 and HPV - 18 positive cells and that mechanisms protecting infected cells against Fas/FasL-mediated apoptosis become defective under the influence of retinol.