Matrix metalloproteinases expression in HL-60 promyelocytic leukemia cellsduring apoptosis

Human promyelocytic leukemia HL-60 cells have been used as a model to study both the expression of matrix-metalloproteinases and the mechanisms of pro grammed cell death. In the present study we examined the expression of thes e proteases in HL-60 cells stimulated by different apoptotic triggers. As s hown by zymography, HL-60 cells released three major isofroms of the matrix -degrading proteases; when the leukemic cells were grown in serum-free cond itions, as well as after hyperthermia and methotrexate treatment, we found a significant loss of the constitutive production of the 92 kDa matrix-meta lloprotease, with an unequivocable molecular and ultrastructural evidence o f programmed cell death. These results suggest that in HL-60 cells the expr ession/release of matrix metalloproteases can be down-regulated in the pres ence of the apoptotic-induced alterations, and that the decreased matrix-de grading capacity of this leukemic cell line during apoptosis may reduce its invasive potential.