Retroviral Gene Transfer Is Inhibited by Chondroitin Sulfate Proteoglycans/Glycosaminoglycans in Malignant Pleural Effusions

Abstract

Gene therapy may be an important adjuvant for treating cancer in the pleural space. The initial results of retroviral gene transfer to cancer cells in malignant pleural effusions revealed that transduction was markedly inhibited, and studies to characterize the inhibitory factor(s) were performed. The inhibition was contained within the soluble, rather than cellular, components of the effusions and was demonstrated with amphotropic, gibbon ape leukemia virus, and vesicular stomatitis virus-glycoprotein pseudotyped retroviral vectors. After excluding complement proteins, a series of studies identified chondroitin sulfates (CSs) as the inhibitory substances. First, treatment of the effusions with mammmalian hyaluronidase or chondroitinases, but not Streptomyces hyaluronidase, abolished the inhibitory activity. Second, addition of exogenous CS glycosaminoglycans mimicked the inhibition observed with pleural effusions. Third, immunoassays and biochemical analyses of malignant pleural effusion specimens revealed CS in relevant concentrations within pleural fluid. Fourth, proteoglycans/glycosaminoglycans isolated from the effusions inhibited retroviral gene transfer. Analyses of the mechanism of inhibition indicate that the chondroitin sulfates interact with vector in solution rather than at the target cell surface. These results suggest that drainage of the malignant pleural effusion, and perhaps enzymatic pretreatment of the pleural cavity, will be necessary for efficient retroviral vector mediated gene delivery to pleural metastases.

Heparin Binds to Murine Leukemia Virus and Inhibits Env-Independent Attachment and Infection

“…In keeping with previous reports (1,2,14,15), soluble heparin potently inhibited the transduction of NIH 3T3 cells by MLV-A (Fig. 1).…”

“…The contribution of such Env-independent attachment to infectivity was not totally clear from this work, although MLV-A poorly infected certain human suspension cells which adsorbed virus particles less efficiently than adherent cell lines. Since soluble GAGs have previously been shown to inhibit transduction by MLV (1,2,14,15) and since GAGmediated interactions are involved in the initial binding of other viruses to the cell surface, we investigated whether a similar mechanism is responsible for Env-independent binding of MLV.…”

Latest Developments in Gene Transfer Technology: Achievements, Perspectives, and Controversies over Therapeutic Applications

“…Interestingly, wild-type foami viruses are resistant to complement-mediated lysis [95] and have a total insert capacity in the virion of approximately 14kb [95]. Conversely, MLV-based retroviral, lentiviral and foami viral vectors pseudotyped either with amphotropic retroviral envelopes or VSV G glycoprotein are susceptible to complement-mediated lysis [135][136][137][138] and their total insert capacity in the virion is in the range of 10kb [5]. It has been demonstrated that packaging cell lines expressing galactosyl(alpha1-3)galactosyl (alphaGal) sugars generate enveloped viruses that are more susceptible to complement attachment [136].…”

Gene transfer vectors derived from equine infectious anemia virus

“…For these experiments, the vesicular stomatitis virus (VSV) envelope glycoprotein (G) was expressed from a plasmid previously constructed by us for generation of VSV-G pseudotyped MuLV vectors. 22,23 Production and testing of EIAV vectors EIAV vectors were produced by CaPO 4 -mediated transient transfection of human 293 cells, as described previously. 23 The three-plasmid cotransfection included the pEV53 gag-pol expression plasmid, the pCI-VSV-G expression plasmid and either a puro or lacZ expression vector plasmid (Figure 2).…”