Expression of soluble and functional full-length human matrix metalloproteinase-2 in Escherichia coli

Characterization of the matrix metalloproteinase-2 (MMP-2) substrates and understanding of its function remain difficult because up to date preparations containing minor amounts of other eukaryotic proteins that are co-purified with MMP-2 are still used. In this work, the expression of a soluble and functional full-length recombinant human MMP-2 (rhMMP-2) in the cytoplasm of Escherichia coli is reported, and the purification of this metalloproteinase is described. Culture of this bacterium at 18 degrees C culminated in maintenance of the soluble and functional rhMMP-2 in the soluble fraction of the E. coli lysate and its purification by affinity with gelatin-sepharose yielded approximately 0.12 mg/L of medium. Western Blotting and zymographic analysis revealed that the most abundant form was the 72-kDa MMP-2, but some gelatinolytic bands corresponding to proteins with lower molecular weight were also detected. The obtained rhMMP-2 was demonstrated to be functional in a gelatinolytic fluorimetric assay, suggesting that the purified rhMMP-2 was correctly folded. The method described here involves fewer steps, is less expensive, and is less prone to contamination with other proteinases and MMP inhibitors as compared to expression of rhMMP-2 in eukaryotic tissue culture. This protocol will facilitate the use of the full-length rhMMP-2 expressed in bacteria and will certainly help researchers to acquire new knowledge about the substrates and biological activities of this important proteinase. (C) 2011 Elsevier B.V. All rights reserved.State of Sao Paulo Research Foundation (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP, State of Sao Paulo Research Foundation

AKT1(low) Quiescent Cancer Cells Promote Solid Tumor Growth

Human tumor growth depends on rapidly dividing cancer cells driving population expansion. Even advanced tumors, however, contain slowly proliferating cancer cells for reasons that remain unclear. Here, we selectively disrupt the ability of rapidly proliferating cancer cells to spawn AKT1(low) daughter cells that are rare, slowly proliferating, tumor-initiating, and chemotherapy-resistant, using beta 1-integrin activation and the AKT1-E17K-mutant oncoprotein as experimental tools in vivo. Surprisingly, we find that selective depletion of AKT1(low) slow proliferators actually reduces the growth of a molecularly diverse panel of human cancer cell xenograft models without globally altering cell proliferation or survival in vivo. Moreover, we find that unusual cancer patients with AKT1-E17K-mutant solid tumors also fail to produce AKT1(low) quiescent cancer cells and that this correlates with significantly prolonged survival after adjuvant treatment compared with other patients. These findings support a model whereby human solid tumor growth depends on not only rapidly proliferating cancer cells but also on the continuous production of AKT1(low) slow proliferators. (C) 2017 AACR