Lentiviruses with trastuzumab bound to their envelopes can target and kill prostate cancer cells

Abstract

In this study, we took advantage of the overexpression of human epidermal growth factor receptor 2 (HER-2) in prostate cancers to design lentiviruses with modified envelope proteins that bind antibodies to specific cell-surface antigens. When bound to trastuzumab (Herceptin, Genentech, CA), lentiviruses were able to selectively infect androgen-sensitive LNCaP and castrationresistant C4-2 human prostate cancer cell lines, both of which express high levels of HER-2. To test for a therapeutic effect, we engineered our antibody-binding lentiviruses to express thymidine kinase, which can convert the non-toxic pro-drug ganciclovir (GCV) into a cytotoxic form. LNCaP and C4-2 cells infected by these viruses were sensitive to GCV killing. In vivo, C4-2 xenograft tumors treated either intratumorally or i.v. with trastuzumab-bound lentivirus expressed luciferase, although the latter route was less tumor specific. When a prostate-specific promoter for governing luciferase expression was combined with trastuzumab-mediated delivery, there was a further enrichment in targeting viral gene expression in prostate tumors. In conclusion, we found that although prostate cancers that express high levels of HER-2 are resistant to the killing effects of trastuzumab, they can be targeted for selective gene expression and destruction by viruses with envelope proteins engineered to bind this antibody.

Selectively Targeting the DNA-binding Domain of the Androgen Receptor as a Prospective Therapy for Prostate Cancer

“…twice daily could be tolerated by the mice with no decrease in body weight over a total duration 4 weeks. The in vivo screening for tumor growth inhibition was initially performed using our previously established castration-resistant tumor xenograft model (37)(38)(39)(40) in castrated hosts (41,42). Post-castration, animals were monitored for regrowth of LNCaP tumors and precastration levels of serum PSA, at which point the mice were treated with compound VPC-14449 (100 mg/kg) or enzalutamide (10 mg/kg) twice daily.…”

Targeting trastuzumab-resistant breast cancer cells with a lentivirus engineered to bind antibodies that recognize HER-2

“…Construction of lentiviral vectors as well as their preparation and characterization were carried out as described previously [19]. One lentiviral vector, in which expression of dual selection markers EGFP and blasticidin-resistant gene (Bsr) is under the control of the ubiquitin promoter and the elongation factor 1 alpha (EF1A) promoter, respectively, was kindly provided by Dr. D. Fink (BC Cancer Agency).…”

“…Trastuzumab resistance was assessed by MTS assay by measuring the viability of cells in the presence of trastuzumab at various concentrations ranging from 2 to 16 lg/ml [19]. Expression of HER-2 on breast cancer cells was assessed by immunocytochemical staining and immunoblotting with anti-HER-2 antibody (R&D Systems, Minneapolis, USA) as described elsewhere [19]. The trastuzumab-resistant BT-474 and MDA-MB-453-sublines are referred to as BT-474 (TR) and MDA-MB-453-(TR), respectively, in the text.…”

“…2 9 10 6 cells in 100 ll PBS were injected subcutaneously in the upper left and lower right on the back of each mouse. Following intra-tumoral or intravenous injection of lentiviral vectors, visualization of firefly luciferase expression was conducted as described [19]. All animal procedures were performed according to the guidelines of the Canadian Council on Animal Care with appropriate institutional certification.…”

Anticancer Gene Transfer for Cancer Gene Therapy

“…Successful use of these vectors has been achieved in PD, metachromatic leukodystrophy, X-Adrenoleukodysrtophy and several immunodefienciencies (WAS, ADA-X SCID). Lentiviruses have also been used for cancer immunotherapy (through enhancement of dendritic cell antigen presentation) of Tcell leukemia or prostate cancer when bound to trastuzumab (Stripecke et al, 2003;Zhang et al, 2009a).…”