ABSTRACT
The greatest challenge in cancer gene therapy is to achieve the high specificity and efficiency in targeting of cancer cells. Because the goal of cancer gene therapy is to eradicate cancer cells, many therapeutic genes could be detrimental if unintentionally expressed in normal cells. Using promoter of the genes which are expressed specifically in cancer cells or have much more expression in cancer cells than normal cells, is very noticeable tool in cancer gene therapy [CGT]. In this study we were searching for cancer specific promoter which could highly express therapeutic gene. In order to apply a cancer specific promoter for creating a CGT construct, a promoter which have 34% similarity to Survivin core promoter was amplified from human genome by using Nested-PCR. Survivin is a member of anti-apoptotic gene and its over-expression was observed in up to 70% of breast cancers. This gene fragment contains two transcriptional binding sites which were similar to Survivin promoter according to the evaluation of Promoter Scan, EPD, Transfac, Compel and TRRD program. These binding sites were recognized by STAT1 and E2F transcription factors. This promoter was cloned into pCDNA3.1/Hygro plasmid in along with hypoxia and estrogen modules and pro-apoptotic gene tBid. Semi-quantitative RT-PCR results of transfected cancer cells showed that this gene fragment [Survivin like promoter] have relatively same potential as CMV promoter to direct tBid gene expression. Utilization of chimeric promoter containing Survivin like promoter could be a promising tool in killing cancer cells naturally by inducing apoptosis. This construct is highly effective in transcriptional targeting of tBid in comparison to control construct