Matrix metalloproteinases and their tissue inhibitors - expression, role and regulation in human malignant non-Hodgkin's lymphomas.

Human malignant non-Hodgkin's lymphomas (NHL) represent a heterogeneous group of neoplasms, which vary in their clinical behavior and pathophysiology. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have been shown to play a role in the pathophysiology and clinical aggressiveness of human NHL. In this setting, MMP-9 and TIMP-1 appear to be the most important members of the MMP and TIMP families, and overexpression of both correlates with a poor clinical outcome of patients with NHL. MMP-9 and TIMP-1, however, act through different mechanisms and are produced by different cell types. Expression of both is upregulated by interleukin-6 (IL-6), a cytokine that is known as one of the factors involved in the pathophysiology of human NHL. In this review we summarize the complex regulation of MMP and TIMP expression in human NHL and propose a mechanism by which MMP-9, TIMP-1 and IL-6 may influence the biology of these tumors.