Stromelysin-3 (ST3), a matrix metalloproteinase (MMP) expressed in aggressive carcinomas, has been shown to promote tumor development in dierent in vivo experimental models. However, the inability of its mature form to degrade extracellular matrix components casts doubt on whether ST3 functions in vivo as a protease. In this study, we evaluated whether the ST3 tumor-promoting eect could be ascribed to its proteolytic activity and whether this putative protease could be targeted with MMP inhibitors. Catalytically inactive mutant cDNA of human (h) ST3 or mouse (m) ST3 were generated and transfected into MCF7 cells. When injected into nude mice in the presence of matrigel, the mutant-bearing cells did not exhibit the enhanced tumorigenicity elicited by MCF7 cells transfected with wild-type ST3 cDNA. In a second approach, TIMP2 overproduction in MCF7 cells expressing hST3 was induced by retroviral infection. The co-expression of ST3 and TIMP2 failed to enhance the tumorigenicity of MCF7 cells. Notably, matrigel depleted of low-molecular-weight proteins and growth factors failed to promote the tumorigenicity of ST3-expressing MCF7 cells. These ®ndings provide the ®rst in vivo evidence that ST3 is indeed a protease that can modulate cancer progression by remodeling extracellular matrix and probably by inducing it to release the necessary microenvironmental factors. Thus, ST3 represents an interesting target for speci®c MMP inhibition.
Co‐injection of fibroblasts with human epithelial breast‐tumor MCF7 cells in the presence of Matrigel enhances tumor growth in nude mice. While most of the matrix metalloproteinases (MMPs) have been shown to be produced by stromal cells, tumor cells such as MCF7 cells are unable to produce MMPs. We therefore, hypothesized that the tumor‐promoting effect of fibroblasts could be related to their production of MMPs. In order to inhibit stromal proteases, over‐production of TIMP‐2 was induced in MCF7 cells by in vitro retroviral‐mediated gene transfer. TIMP‐2‐producing MCF7 cells were then co‐injected with fibroblasts into nude mice. Alternatively, we evaluated the effect of Batimastat, a synthetic inhibitor of MMPs, on the tumorigenicity of MCF7 cells co‐inoculated with fibroblasts into nude mice. Both physiological (TIMP‐2) and synthetic (Batimastat) inhibitors of MMPs were able to abolish the tumor‐promoting effect of fibroblasts. On the contrary, they failed to modulate the tumorigenicity of MCF7 cells injected alone. Interestingly, Matrigel from which low‐molecular‐weight proteins or growth factors had been removed failed to favor the tumorigenicity of MCF7 cells inoculated with fibroblasts. These findings emphasize the importance of fibroblasts in cancer progression, and suggest that their role could be related at least in part to production of proteases which can induce the release of factors from the extracellular matrix. Int. J. Cancer 76:267–273, 1998.© 1998 Wiley‐Liss, Inc.
To investigate the factors influencing the bystander effect Ð a key element in the efficacy of suicide gene therapy against cancer Ð we compared the effect triggered by four extremely efficient gene / prodrug combinations, i.e., VZVtk / BVDU, the thymidine kinase of Varicella zoster virus associated with ( E ) -5 -( 2 -bromovinyl ) -2 H -deoxyuridine; VZVtk / BVaraU, the same enzyme associated with ( E ) -5 -( 2 -bromovinyl ) -1 --D -arabinofuranosyluracil; HSVtk / BVDU, the association of the Herpes simplex virus thymidine kinase with BVDU; and the classical HSVtk / GCV ( ganciclovir ) paradigm. The cells used, the human MDA -MB -435 breast cancer, and the rat 9L glioblastoma lines were equally sensitive in vitro to these four associations. In both cell types, the combinations involving pyrimidine analogues ( BVDU, BVaraU ) displayed a smaller bystander killing than the combination involving the purine analogue ( GCV ) . In addition, the bystander effect induced by all the tk / prodrug systems was reduced in MDA -MB -435 cells in comparison to 9L cells; albeit, the viral kinases were produced at a higher level in the breast cancer cells. All systems induced apoptotic death in the two cell types, but the MDA -MB -435 cells, deprived of connexin 43, were noncommunicating in striking contrast with the 9L cells. That functional gap junctions have to be increased in order to improve the breast cancer cell response to suicide gene therapy was demonstrated by transducing the Cx43 gene: this modification enhanced the bystander effect associated in vitro with GCV treatment and, by itself, decreased the tumorigenicity of the untreated cells. However, the noncommunicating MDA -MB -435 cells triggered a significant bystander effect both in vitro and in vivo with the HSVtk / GCV system, showing that communication through gap junctions is not the only mechanism involved. Cancer Gene Therapy ( 2000 ) 7, 1456 ± 1468Key words: Suicide gene therapy; viral thymidine kinases; bystander effect; connexin 43.G ene therapy is a promising approach for the treatment of human cancers. The introduction into tumoral cells of à`s uicide'' gene, whose product is able to activate a nontoxic prodrug into a toxic compound, is a powerful method to selectively kill the modified cells. The most frequently used system consists of transferring the Herpes simplex thymidine kinase gene ( HSVtk ) into tumor cells and to treat them with ganciclovir (GCV ) . This guanosine analogue is specifically monophosphorylated by the viral kinase and then converted by cellular enzymes into the triphosphate derivative, which, upon incorporation into elongating DNA, induces cell death by premature chain termination. The efficacy of the HSVtk / GCV system first described by Moolten 1 in 1986 has been demonstrated in many different types of tumoral cells in vitro and in vivo, and it is currently under clinical investigation as treatment for a wide variety of cancers.A major obstacle to successful cancer gene therapy is the poor efficiency of the gene transfer process r...
The production of singlet oxygen (1O2) upon irradiation of several dyes in aqueous solution at pH 9.0, was quantitatively analyzed on the basis of the appearance of stable nitroxide radicals using the amine 2,2,6,6‐tetramethyl‐4‐piperidone as 1O2 acceptor. The dyes were checked for purity, their concentrations uniformized in terms of absorbance values and a correction factor was introduced which took into account the amount of photons absorbed. The rates of 1O2 production (in arbitrary units per min) were: 71 with rose Bengal, 70 with methylene blue, 61 with eosin Y, 18 with thiopyronine, 10 with proflavine and 9 with acridine yellow. Production of 1O2 was not observed with 9‐aminoacridine, acridine orange, quinacrine and ethidium bromide. Irradiated lumichrome initiated, with the same amine, another type of reaction. The rates of two other photoreactions were also determined under similar experimental conditions by following (i) the deoxyguanosine decomposition in which case the reaction was found to be less sensitive but largely parallel to the 1O2 production and (ii) the bacteriophage ØX174 inactivation in which case the dyes showed differences in their relative efficiencies. The proteinic capsid of the phage appeared as an effective impermeability barrier towards externally generated 1O2. Moreover, some of the dyes studied intercalated into the phage DNA, a process known to favor radicalar reactions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.