In a multiplexed analysis of RAS-dependent signaling, Mac-1(Low) cells, which harbor leukemia stem cells, were preferentially sensitive to NRAS(G12V) withdrawal.
In an attempt to maximize transfer and expression of CD18, we evaluated retroviral vectors with and without the neomycin selectable marker, with a modified tRNA primer binding site designed to prevent inhibition of gene expression, and with two different viral envelope proteins produced by using the amphotropic retrovirus packaging cell line PA317 or the gibbon ape leukemia virus packaging cell line PG13.
While in normal individuals all these molecules are broadly expressed on leukocytes, in patients with leukemias the following deviations were observed: (a) at least one of the examined molecules was missing in 64/68 cases (94%); in 12/68 cases (18%) both molecules LFA-1 and ICAM-1 were missing, in 37/68 (54%) either LFA-1 or ICAM-1, and in 15/68 cases (22%) adhesion molecules other than LFA-1 or ICAM-1 were missing; (b) the expression of CD11a/CE18, CD58, CD59 on leukemic cells was heterogeneous, without any clear correlation to the subclass of leukemia; (c) in the majority of cases, CD54 (45/68; 66%) and CD44 (36/68; 53%) were missing, however showing a tendency of expression on leukemic cells with more mature immunophenotype.