Integrin receptors and TGF-Beta expression in chronic myeloid leukemia cells

ABSTRACT

To understand relationiship between transforming growth factor beta-1 (TGF-ß1) and the integrin profile presented by chronic myeloid leukemia cells, we have studied, using Northen analysis, the expression of TGF-ß1 messenger RNA (TGF-ß mRNA) in myeloid cell lines and in patient with acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). In addition we determined the positivity for alfa4 and alfa5 integrin moleculas in those cell using specific monoclonal antibodies and flow cytometry. CML patients (N=3) presented mean values of alfa4 higher (alfa4 60 ñ 20 per cent); alfa5 70 ñ 41 per cent) than AML (N=10) blast cells (alfa4 25 ñ 23 per cent); alfa5 18 ñ 16 per cent). Northern analysis revealed an almost four-fold higher expression of TGF-ß mRNA in K562 (derived from a patient with chronic myeloid leukemia) compared to the myeloblastic cell line HL60. The highest TGF-ß mRNA levels were seen in the U937 lineage. CML leukemic cells (N=3) showed high TGF-ß mRNA levels comparable to the levels expressed by K562 which was paralleled by high ß1 integrin mRNA. AML blast cells presented a variable degree of expression of TGF-ß mRNA when compared to HL60. One patient with acute megakaryoblastic leukemia (FAB subtype M7), usually associated with myelofibrosis, presented the highest TGF-ß mRNA levels. We conclude that studing TGF-ß1 and its mechanisms of action will help in understanding fibrosis in leukemic patients, and perhaps to design treatments for such conditions