Robust prostate-specific expression for targeted gene therapy based on the human kallikrein 2 promoter

Hum Gene Ther. 2001 Mar 20;12(5):549-61. doi: 10.1089/104303401300042483.


Tissue-specific transcriptional regulatory elements can increase the safety of gene therapy vectors. Unlike prostate-specific antigen (PSA/hK3), whose expression displays an inverse correlation with prostate cancer grade and stage, human glandular kallikrein 2 (hK2) is upregulated in higher grade and stage disease. Therefore, our goal was to develop a strong and prostate-specific hK2-based promoter for targeted gene therapy. We identified the minimum "full-strength" hK2 enhancer and built transcriptional regulatory elements composed of multiple tandem copies of this 1.2-kb enhancer, fused to the hK2 minimal promoter. Relative to the weak induction of the minimal hK2 promoter by androgen analog (R1881) in androgen receptor (AR)-positive LNCaP cells, transcriptional activity was increased by 25-, 44-, 81-, and 114-fold when one to four enhancers were spliced to the hK2 promoter, respectively. In contrast, the enhancer/promoter elements were inactive in the AR(-) prostate cancer line PC-3 and in a panel of nonprostate lines, including 293, U87, MCF-7, HuH-7, and HeLa cells. Furthermore, we generated a recombinant adenovirus, ADV.hK2-E3/P-EGFP, expressing enhanced green fluorescent protein (EGFP) under the control of the hK2 triplicate enhancer/promoter, and compared its properties with ADV.CMV-EGFP expressing EGFP under the control of the cytomegalovirus (CMV) enhancer/promoter. Unlike the CMV promoter, the hK2-E3/P promoter was at least 100-fold inducible by R1881 in the adenoviral backbone. Compared with in situ injection of subcutaneous LNCaP tumors with ADV.CMV-EGFP, which led to detectable EGFP expression in tumor, liver, and brain tissue, ADV.hK2-E3/P-EGFP injection led to robust but tumor-restricted EGFP expression. These results suggest that the hk2 multienhancer/promoter should be a powerful novel reagent for safer targeted gene therapy of prostate cancer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenoviridae / genetics
  • Animals
  • Binding Sites
  • Brain / metabolism
  • Cytomegalovirus / genetics
  • Dose-Response Relationship, Drug
  • Enhancer Elements, Genetic
  • Flow Cytometry
  • Genetic Therapy / methods*
  • Genetic Vectors / metabolism
  • Green Fluorescent Proteins
  • HeLa Cells
  • Humans
  • Liver / metabolism
  • Luminescent Proteins / metabolism
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Microscopy, Fluorescence
  • Models, Genetic
  • Neoplasm Transplantation
  • Plasmids / metabolism
  • Promoter Regions, Genetic*
  • Prostate / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spectrometry, Fluorescence
  • Tissue Kallikreins / biosynthesis*
  • Tissue Kallikreins / genetics*
  • Transcription, Genetic
  • Transduction, Genetic
  • Transfection
  • Tumor Cells, Cultured
  • Up-Regulation


  • Luminescent Proteins
  • Green Fluorescent Proteins
  • Tissue Kallikreins