Replication of mutant herpes simplex virus type 1 in human prostate and nonprostate cancer cells under the control of the probasin promoter

The use of tissue- or tumor-selective promoters in targeted gene therapy for prostate cancer depends on strong and selective activity. The -426 to +28 bp probasin (PB) promoter has the potential to target selected genes to the prostatic epithelial cells. We showed that in the assay of luciferase reporter gene driven by PB promoter, activation of luciferase expression was 1.5-fold increase in human prostate cancer cell LNCaP relative to non-small cell lung cancer cell H460. Significant increase of luciferase activity was observed in both cell lines when infection with ICP27 (-) HSV-1 was added to PBluciferase plasmid transfected LNCaP and H460 cells. In addition, an expression vector (PB-ICP27) was generated in which one of the herpes simplex virus type 1 (HSV-1) immediate early (IE) genes required for viral replication~ICP27 was regulated by PB promoter. This vector was transfected into LNCaP, H460 and one other nonprostate cancer cell HepG2 (hepatoma), the cell lines were then infected with ICP27 (-) HSV-1 and resulting viral stock from these cells were used to infect ICP27 expression 2-2 cell. The plaque yields from infected 2-2 cells were counted and reflected the production of ICP27 (-) HSV-1 replication in PB-ICP27 vector transfected cells that can express ICP27 protein. Although we found that the profound viral replication was observed in LNCaP cells compared to that of HepG2 cells, the production of viral replication in H460 cells was surprisingly significant higher than that in LNCaP cells and was contrasted to our PB-driven luciferase assay result. Our study demonstrates that (1). -426 to +28 bp PB promoter shows relative tissue-specific activity; (2). Infection with ICP27 (-) HSV-1 can enhance the expression levels of reporter gene driven by PB promoter and ICP27 (-) HSV-1 can only replicate in the cells expressing ICP27 protein; (3). The vector construct containing ICP27 gene driven by PB promoter may not be an ideal delivery system for the purpose of prostate tissue-specific gene expression.Surgery, Department ofMedicine, Faculty ofGraduat