Background: Chronic lymphocytic leukemia (CLL) is an indolent B-lineage neoplasm,
characterized by clonal expansion of CD5 positive B cells with constitutive activation of survival
pathways including NF-kB. Pentoxifylline, a xanthine-derivative compound indicated for the treatment
of microvascular disturbancies, has been suggested to have anti-proliferative and anti-metastatic activities
in various types of cancer. In the present study we extend these data showing one of the potential
molecular mechanisms through which Pentoxifylline may promote apoptosis in CLL clonal lymphocytes.
Methods: Peripheral blood mononuclear cells were isolated from 15 CLL patients 0 RAI stage and 15
healthy volunteers and treated for 24 and 48 hours with Pentoxifylline. Apoptosis induction was evaluated
through Annexin V and TUNEL assays. Mitochondrial membrane potential depolarization analysis,
active Caspase-3 assay, reactive oxygen species generation and Western Blot were assessed to further
investigate the alterations induced by Pentoxifylline.
Results: We observed a statistically significant occurrence of apoptosis, DNA fragmentation and active
Caspase-3 in lymphocytes from CLL patients compared to healthy volunteers after 48 hours of Pentoxifylline
treatment. To clarify the molecular mechanism of the drug, we also evaluated the expression
levels of NF-kB/p65 and its related proteins. In treated CLL cells, NF-kB/p65 was significantly
decreased in comparison to normal cells, whereas we observed a less marked reduction of Bcl-2 expression.
The treatment also induced a decrease of Mcl-1 in CLL cells with a greater down-regulation
of the anti-apoptotic alternatively spliced isoform.
Conclusion: These findings showed that Pentoxifylline induced apoptosis in leukemic cells through a
molecular mechanism that involves the NF-kB signaling.