Oncolytic Efficacy and Enhanced Safety of Measles Virus Activated by Tumor-Secreted Matrix Metalloproteinases

Abstract

Cancer cells secrete matrix metalloproteinases (MMP) that degrade the extracellular matrix and are responsible for some hallmarks of malignant cancer. Many viruses, including a few currently used in oncolytic virotherapy clinical trials, depend on intracellular proteases to process their proteins and activate their particles. We show here for measles virus (MV) that particle activation can be made dependent of proteases secreted by cancer cells. The MV depends on the intracellular protease furin to process and activate its envelope fusion (F) protein. To make F protein activation cancer cell specific, we introduced hexameric sequences recognized by an MMP and identified the mutant proteins most effective in fusing MMPexpressing human fibrosarcoma cells (HT1080). We showed that an MMP inhibitor interferes with syncytia formation elicited by mutant F proteins and confirmed MMP-dependent cleavage by Edman degradation sequence analysis. We generated recombinant MVs expressing the modified F proteins in place of furin-activated F. These viruses spread only in cells secreting MMP. In nude mice, an MMP-activated MV retarded HT1080 xenograft growth as efficiently as the furin-activated MV vaccine strain. In MV-susceptible mice, the furin-activated virus caused lethal encephalitis upon intracerebral inoculation, whereas the MMP-activated did not. Thus, MV particle activation can be made dependent of proteases secreted by cancer cells, enhancing safety. This study opens the perspective of combining targeting at the particle activation, receptor recognition, and selective replication levels to improve the therapeutic index of MV and other viruses in ongoing clinical trials of oncolysis. (Cancer Res 2006; 66(15): 7694-700)

Anticancer Gene Transfer for Cancer Gene Therapy

“…Surprisingly, the modified viruses could only be activated and exert oncolysis preferentially in cells that express MMPs. Similar results were obtained from experiments in mice in which modified viruses were injected in a background of MMP absence and so no damage (cell death) or infection were observed after viral distribution (Morling et al, 1997;Peng et al, 1999;Springfeld et al, 2006). Importantly the safety of the viruses was greatly enhanced compared with the wild type counterparts through viral tropism re-targeting so the manipulation was at the level of particle activation.…”

Gene therapy progress and prospects cancer: oncolytic viruses

“…19 Oncolytic HSV encoding dominant-negative fibroblast growth factor receptor or antiangiogenic protein platelet factor-4 led to significant reduction in tumor vasculature and as a result, significantly enhanced therapeutic efficacy. 20,21 Others have engineered oncolytic virus replication to be activated by tumor matrix metalloproteinases (MMP), 22 and shown that MMP-8 gene delivery enhanced the efficacy of oncolytic adenovirus. 23 An alternative approach is to coadminister therapeutic agents with the virus.…”

Generation of optimized and urokinase-targeted oncolytic Sendai virus vectors applicable for various human malignancies

“…MMP-G4/ MTS showed the highest efficiency in forming syncytia under cotransfection of both MT1-MMP and MMP2. It has been reported that MMP-G2 (-PQG/LYA-) is an efficient sequence in MMP-expressing HT-1080 cell, in the use of recombinant measles virus, 12 but this was not the case with SeV under similar experimental conditions using HT-1080 cells (data not shown).…”

“…We found more sensitive linker sequences (MMP-G4/MTS: -PRAMTS-; uPA2: -SGRS-) than that of the prototype vectors (MMP-G1/MTS: -PLGMTS-and uPA1: -VGR-) ( Figure 2); however, the sequence-specific sensitivity may depend on the type of virus. For example, MMP-activated recombinant retroviruses could be generated by the introduction of -PLGLYA-hexamer, and a similar sequence (MMP-G2: -PQGLYA-) could be adapted to the oncolytic measles virus vector, as demonstrated by Springfeld et al 12 Measles virus-F protein containing MMP-G2 (-PQGLYA-) sequence, called 'MMP-A1' in their study, could lead HT1080 cells 10 6 ) and the samples were incubated in 6-well culture dish for 2 days. In each case, the conditioned medium was collected and applied to a gelatin gel plate.…”

“…8,12,19,20 Their data show that those vectors can target the cytotoxicity of the fusogenic membrane glycoprotein in MMP-overexpressing tumor lines and xenografts, and maintain significant antitumor activity both in vitro and in vivo. MMPtargeted vectors, irrespective of the vectors' backbone, may be confronted with a similar difficulty in clinical settings.…”