Downregulation of Breast Cancer Expression by Small Molecule Drugs

摘要

Breast cancer is the most common cancer among women and the second leading cause of cancer deaths in women today, after lung cancer. Twenty to thirty percent of all breast cancers show overexpressed Her-2/neu, which causes a highly intractable malignant cancer phenotype and almost always spells out poor prognosis and therapeutic outcome. In order to transcriptionally downregulate the Her-2/neu oncogene, we used a combination of a hairpin polyamide and recombinant transcriptional repressor proteins that specifically bind to the AP-2 site on the Her-2/neu gene promoter. Our experiments revealed that the hairpin polyamide HPA-1 was extremely specific to the TATA box of the Her-2/neu promoter and binds with high affinity in vitro, but its in vivo efficacy was limited. However, our experiments with the KRAB and AP-2 based transcriptional repressor proteins showed promise for transcriptional regulation of the Her-2/neu expression. The data from our experiments showed that the recombinant proteins also repress the transcription of other pro- survival genes like cyclin D1 and VEGF. Proliferation studies using WST-1 assays, FACS-cell cycle profile experiments and caspase assays showed that the KRAB-recombinants inhibit cell proliferation and induce caspase3/7 mediated apoptosis. In summary, the KRAB-AP2 recombinant proteins possess the potential to be used as gene therapeutics for Her-2 over-expressing breast cancers and can also be used as gene discovery tools to study cell cycle regulation, cellular proliferation and tumor formation with relation to the genes they regulate.