Hybrid promoters directed tBid gene expression to breast cancer cells by transcriptional targeting

Biotechnol Prog. Mar-Apr 2010;26(2):505-11. doi: 10.1002/btpr.353.


Developing cancer gene therapy constructs based on transcriptional targeting of genes to cancer cells is a new and promising modality for treatment of cancer. Introducing truncated Bid (tBid), a recently known member of the Bcl-2 family, eradicates cancer cells efficiently. For transcriptional targeting of tBid, two dual-specificity promoters, combining cancer specific core promoters and response modules, were designed. These two core promoter modules contained cancer specific promoters of MUC1 and Survivin genes accompanied by hypoxia-responsive elements and estrogen responsive elements (microenvironment condition of breast cancer cells) which were employed to achieve a higher and more specific level of tBid expression in breast cancer cells. Correlation of the level of tBid expression in normal and cancer cell lines with promoter activity was measured by RT-PCR after treatment with hypoxia and estrogen. The level of tBid expression under control of new hybrid promoters was compared with its expression under control of cytomegalovirus (CMV) promoter as a control. Our data revealed that the level of tBid expression in breast cancer cells were nearly 11 times more than normal cells because of the cancer specific promoters, although tBid expression under control of CMV promoter was almost the same in normal and cancer cell lines. Increased apoptosis was detected in the transfected breast cancer cell lines by the Caspase-3 activity assay. The application of these promoters may prove to have the advantage of tumor selective gene therapy in breast cancer cells and low-potential toxicity for normal tissues.

Publication types

  • Comparative Study

MeSH terms

  • Apoptosis / physiology
  • BH3 Interacting Domain Death Agonist Protein / biosynthesis*
  • BH3 Interacting Domain Death Agonist Protein / genetics
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Caspase 3 / metabolism
  • Cell Hypoxia
  • Cell Line, Tumor
  • Cloning, Molecular
  • Estrogens
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Inhibitor of Apoptosis Proteins
  • Microtubule-Associated Proteins / genetics
  • Mucin-1 / genetics
  • Promoter Regions, Genetic
  • Reverse Transcriptase Polymerase Chain Reaction
  • Survivin
  • Transfection


  • BH3 Interacting Domain Death Agonist Protein
  • BIRC5 protein, human
  • Estrogens
  • Inhibitor of Apoptosis Proteins
  • MUC1 protein, human
  • Microtubule-Associated Proteins
  • Mucin-1
  • Survivin
  • Caspase 3