The antiangiogenic phloroglucinol hyperforin inhibits the secretion of proMMP-2, proMMP-9 and VEGF-A during apoptosis of primary acute myeloid leukemia cells

Abstract

Aim: Angiogenesis is observed in acute myeloid leukemia (AML). AML cells abnormally proliferate and are resistant to death. Positive regulators of angiogenesis, VEGF-A and matrix metalloproteinases (MMPs) 2 and 9 are markers of disease status in AML. The natural phloroglucinol hyperforin (HF) displays antitumoral properties of potential pharmacological interest. Herein, we investigated the effects of HF on MMP-2/9 and VEGF-A expression and survival of primary AML cells.Methods: Blood and bone marrow samples were collected in 45 patients with distinct subtypes defined by French American British classification, i.e., M0, M1, M2, M3, M4, and M5. Levels of MMPs and VEGF-A in leukemic blood cells and culture supernatants were determined by RT-PCR, ELISA, and gelatin zymography (MMPs). The balance between cell death and survival was assessed by flow cytometry with analysis of phosphatidylserine externalization and caspase-3 activation.Results: The administration of HF promoted a caspase-associated apoptosis in primary AML blasts (from blood and bone marrow), but not normal blood cells and monocytes. In addition, HF inhibited the levels of secreted proMMP-2, proMMP-9, and VEGF-A without altering transcripts. The induction of apoptosis by HF significantly paralleled the inhibition of MMP-2/9 and VEGF-A release by HF. No differences were seen in response to the deleterious effects of HF between AML cells of distinct subtypes.Conclusion: Our results suggest that HF, through its proapoptotic and potential antiangiogenic properties (by inhibiting MMP-2/9 and VEGF-A) on primary AML cells, might be a useful experimental agent, in combination with existing drugs, for new therapeutic approaches in the treatment of this incurable disease