Implicación del colesterol de membrana en la proliferación, ciclo y diferenciación de las células leucémicas humanas HL-60

Abstract

Introduction Cholesterol metabolism is increased in leukaemia cells and, accordingly, the use of chemotherapeutic agents in combination with statins for cancer treatment is being evaluated. In our laboratory, we demonstrated that cholesterol deficiency, as produced by distal inhibitors of the cholesterol biosynthesis pathway, induces the differentiation of HL-60 human leukaemia cells through the granulocytic pathway. The aim of the present work was to determine whether the selective extraction of cholesterol from the cell membrane induces cell differentiation, which may open new possibilities in cancer therapy and other proliferative processes. Material and methods Promyelocytic HL-60 cells were maintained in a cholesterol-free medium. Cholesterol was extracted by incubating the cells in the presence of methyl-β-cyclodextrin. Cholesterol cell content was measured by HPLC; cell proliferation was assessed by cell counting; cell cycle distribution was analysed by flow cytometry. Cell differentiation was assessed by measuring CD11c expression by flow cytometry and NADPH oxidase components by Western blot. Results Treatment with methyl-β-cyclodextrin reduced the cholesterol content in cells, and resulted in cell proliferation inhibition, the induction of CD11c expression and the synthesis of p47 phox and p67 phox. Conclusions Selective extraction of membrane cholesterol in HL-60 cells triggers cell differentiation, as indicated by the expression of both CD11c and NADPH oxidase components. Results Treatment with methyl-β-cyclodextrin reduced the cell cholesterol content and inhibited cell proliferation in a dose-dependent manner. As this treatment is prolonged, part of the cells die but a substantial proportion of cells survives and acquire differentiation markers, such as CD11c, p47 phox and p67 phox. Conclusions Selective extraction of membrane cholesterol in HL-60 cells induces cell cycle arrest, which is followed by cell death and, alternatively, cell differentiation, as indicated by the expression of both CD11c and NADPH oxidase components.