Differential inhibition by α- and β-tocopherol of human erythroleukemia cell adhesion:: Role of integrins

The effect of alpha- and beta -tocopherol on human erythroleukemia cell (HEL) adhesion induced by phorbol 12-myristate 13-acetate (PMA) has been studied. Adhesion induced by PMA stimulation was prevented by 44.5% by physiological concentrations of alpha -tocopherol. Under the same experimental conditions, P-tocopherol, an analogue of cr-tocopherol, produced 11% inhibition of adhesion. Cell response gradually increased from 0 to 24 h of alpha -tocopherol treatment. Only a slight time dependency of beta -tocopherol inhibition was observed. Another human erythroleukemia cell line (K562) and the human monocyte tumor cell line U937 showed 5.0 and 11.2% inhibition, respectively. Similar to alpha -tocopherol, the protein kinase C inhibitor, Calphostin C, and the MAPK inhibitor, PD98059, prevented PMA-induced cell adhesion, An inhibition of ERK-1 phosphorylation was observed for alpha -tocopherol only in HEL, implying that MAP kinase pathway is involved in this cell Line. Fluorescence-activated cell sorting (FACS), by using various integrin specific monoclonal antibodies, has shown that alpha (1-6), beta1, and alphav integrins are less expressed at the cell surface after alpha -tocopherol treatment. Beta-tocopherol treatment was less effective. (C) 2001 Elsevier Science Inc.