Fig. 1

Chk1 (a) and Chk2 (b) mRNA expression levels in leukemia cell lines (BV-173, SUP-B15, REH, NALM-6, NALM-19, MOLT-4, RPMI-8402, and CCRF-CEM), blast cells from 54 adult newly-diagnosed ALL cases, and in normal bone marrow mononuclear cells (MNC). Results are expressed as Log10 2exp[−(ΔΔCt)], and they are the mean of at least two different replicates. c Immunohistochemical profile of the 60 ALL (36 B-ALL and 24 T-ALL); a red box indicates expression of the marker, whereas a green box signifies negativity (samples were considered positive if 30 % or more of the cells were stained with an antibody); gray box indicates a not evaluable reaction due to a core loss in TMA. The figure allows the assessment of the co-expression of the DNA damage markers in individual samples. d Immunohistochemical expression of Chk1, phosphorylated Chk1 (Ser345), Chk2, phosphorylated Chk2 (Thr68), and phosphorylated H2A.X (Ser139) (γ-H2A.X) in thymus, reactive follicle (RF), T-ALL and B-ALL. The figure highlights the close similarity between expression profiling of B- and T-ALL, characterized by a high percentage of cases Chk1⁺, pChk1⁺, Chk2⁺, Cdc25C, pCdc25C, pH2A.X⁺ and, in a lesser extent, pChk2⁺, and its distinction with the expression profiling of the non-tumoral populations as maturing thymocytes, which were substantially negative for these seven proteins and as B lymphocytes of reactive follicles, which resulted Chk1 weakly ⁺, Chk2⁺, Cdc25C⁺ but negative for the corresponding phosphorylated forms and pH2A.X. (a) Thymus: thymocytes Chk1⁻ (×400); (b) RF: B lymphocytes in mantle zone (MZ) and germinal center (GC) showing weak Chk1 positivity (×100); (c) strong expression of Chk1 in T-ALL; and (d) B-ALL (×400). (e) Thymus: thymocytes pChk1⁻ (×400); (f) RF: B lymphocytes in MZ and GC pChk1⁻; (g) strong positivity of pChk1 in T-ALL; and (h) B-ALL (×400). (i) Thymus: normal lymphoblasts Chk2⁻ (×400); (j) RF: B lymphocytes in MZ and GC showing diffuse Chk2 positivity (×100); (k) strong nuclear staining for Chk2 in T-ALL; and (l) B-ALL (×400). (m) Thymus: thymocytes pChk2⁻ (×400); (n) RF: B lymphocytes in MZ and GC pChk2⁻ (×100); (o) diffuse expression of pChk2 in T-ALL; and (p) B-ALL (×400). (q) Thymus: normal lymphoblasts negative for Cdc25C (×400); (r) RF: B lymphocytes in mantle zone (MZ) and germinal center (GC) showing weak Cdc25C positivity (×100); (s) strong nuclear staining for Cdc25C in T-ALL; and (t) B-ALL (×400). (u) Thymus: thymocytes pCdc25C⁻ (×400); (v) RF: B lymphocytes in MZ and GC pCdc25C⁻ (×100); (w) diffuse expression of pCdc25C in T-ALL; and (x) B-ALL (×400); (y) Thymus: normal lymphoblasts negative for pH2A.X (γ-H2A.X) (×400); (z) RF: MZ B and GC lymphocytes substantially pH2A.X (γ-H2A.X)-negative, with only occasional GC positive cells (×100); (aa) strong nuclear staining for pH2A.X (γ-H2A.X) in T-ALL; and (ab) B-ALL (×400)