The expression of CD73 on pathological B-cells is associated with shorter overall survival of patients with CLL.

CD73 is a membrane-bound enzyme that catalyzes the extracellular conversion of adenosine monophosphate to adenosine. Adenosine is thought to play a role in promoting tumor growth and survival together with suppressing the host immune responses, which contribute to the multistep process of tumorigenesis. Here, we studied the expression of this antigen in chronic lymphocytic leukemia (CLL). The expression of CD73 was analyzed by multiparametric flow cytometry on normal and pathological B-cells from peripheral blood and bone marrow samples from 71 patients with CLL. Pathological B-cells expressed significantly lower levels of CD73 than normal B-cells (p<0.01). Patients with splenomegaly showed a higher expression of CD73 on pathological B-cells than patients without splenomegaly (p<0.05). The expression of CD73 also correlated with beta-2-microglobulin levels (p<0.05). Clinically, patients with higher levels of CD73 versus those with lower expression presented with shorter overall survival (median OS of 65 vs. 113 months, p<0.05). Our data indicate that CD73 may play a role in CLL pathophysiology, is correlated with poor clinical and biological prognostic factors and may be of potential value as a prognostic marker and therapeutic target.

Cytogenetic abnormalities predict treatment-free interval and response to therapy in previously untreated chronic lymphocytic leukemia patients.

We evaluated the prognostic impact of chromosomal abnormalities as detected by interphase fluorescence in situ hybridization (iFISH) in 86 chronic lymphocytic leukemia (CLL) patients. Overall, 39 of 86 (45%) patients displayed one (35%) or more (10%) chromosomal abnormalities, del13q (31%) being more frequently detected than trisomy 12 (19%) followed by del11q (17%), del17p (6%) and del6q (5%). Significant differences in the treatment free intervals (TFIs) were observed among individual cytogenetic subgroups (p=0.027) with the shortest mean TFIs in subgroups with del17p, del11q and trisomy 12 (10, 12 and 14 months, respectively) as compared to subgroups with normal cytogenetics (38 months) and del13q (68 months). Poor response to therapy was observed in subgroups with del11q (p=0.044) and trisomy 12 (p=0.047) while patients with normal cytogenetics had good response (p=0.003). Furthermore, del17p and del11q were associated with highest tumor burden and disease activity as reflected by corresponding laboratory data.

Hypocrellin and hypericin-induced phototoxicity of HL-60 cells: apoptosis or necrosis?

Hypericin and hypocrellin are potential antiviral and antineoplastic agents with multiple modes of light-induced biological activity connected with a production of singlet oxygen and/or excited-state proton transfer and consequent pH drop formation in the drugs environment. In present work light-induced cytotoxicity of hypericin and hypocrellin and mechansim of cell death (apoptosis or necrosis) on human leukemic cell line HL-60 was studied. As a mean for apoptosis detection we used poly (ADP-ribose) polymerase (PARP) as a sensitive marker of early stages of apoptosis. Our results show that exposition of HL-60 cells to hypericin (1 x 10(-5) mol x l(-1)) for 4 hours has no effect on PARP cleavage. However, after 24 and 48 hours of illumination there is evident that hypericin in this concentration cleaved PARP (116 kDa) into two fragments (85 and 25 kDa). Contrary to hypericin, hypocrellin in concentration 1 x 10(-5) mol x l(-1) after 4 hours of illumination cleaved PARP into two fragments typical for apoptosis. In lower concentration (1 x 10(-6) mol x l(-1)) hypocrellin possess also significant cytotoxic activity. Because we detected no fragmentation of PARP in all observed time periods we suggest that cytotoxic effect of hypocrellin in this concentration is due to induction of necrosis. Our results support the hypotesis that the hypericin and hypocrellin has similar mechanism of action and illumination increases cytotoxic effect of both agents.