Conclusion
We conclude that primary human AML cells show constitutive release of both MMPs and TIMPs, and this release may be important for leukemogenesis and possibly also for chemosensitivity.
Methods
AML cells were cultured in vitro either alone or together with microvascular endothelial cells, and levels of MMPs and TIMPs were determined in culture supernatants.
Results
AML cells showed constitutive release of several MMPs and TIMPs. For all patients, detectable MMP-10 release was observed, and most patients showed detectable release of at least one additional MMP, usually MMP-9 or MMP-2. A significant correlation was found between MMP-9 and TIMP-1 release and the release of several CCL and CXCL chemokines. MMP-9 release was higher for AML cells with monocytic differentiation corresponding to the FAB-subtype M4/M5 AML; it was mainly released in its inactive form, but endogenously active MMP-9 could be detected even in the presence of the constitutively released TIMP-1/2. Endothelial cells released relatively high levels of MMP-10, and these levels were further increased by coculture with AML cells. Patients achieving complete hematological remission after only one induction cycle showed relatively low constitutive MMP-2 release.