The haplotype of three polymorphisms in the SATB1 promoter-region and impact on survival in breast cancer patients.
584 Background: Special AT-rich sequence binding protein 1 (SATB1) has regulatory effects on gene expression and appears to play an important role in tumor progression. We screened the promoter region of the SATB1 gene for polymorphisms, evaluated the corresponding haplotypes regarding alterations in promoter activity in vitro and analyzed the impact of these haplotypes on the clinical course of breast cancer patients. Methods: 241 caucasian breast cancer patients who had been treated were enrolled in this retrospective analysis. The median follow up time was 93 months (4-155 months). PCR products from DNA of 10 healthy unrelated volunteers were analyzed to identify new polymorphisms within the promoter region. Genotyping was conducted using restriction length polymorphism and pyrosequencing. PCR constructs with the respective alleles from the four most frequent haplotypes were cloned into the vector pGEM-Teasy (Promega Corporation, Madison, WI, USA) and then transferred into the luc2-containing reporter vector pGl 4.10 Vector (Promega) for transfection of HEK293 cells. The pGl 4.73 Vector (Promega), containing hRluc, was used for norming the transfection rates. Results: Sequencing the region -3807bp to -2828 upstream from ATG of ten healthy blood donors, we found three single nucleotide polymorphisms SNPs consisting of base exchanges, -3600T>C, -3363A>G and -2984C>T.The SATB1 -3600T/-3363A/-2984C haplotype had a lower promoter activity than all other constructs in vitro and showed a significant association with the nodal status (p=0.049). Kaplan-Meier survival analysis revealed a significantly better survival for homozygous SATB1 -3600T/-3363A/-2984C haplotype carriers compared with heterozygous or the other haplotypes (p=0.033). Conclusions: The SATB1 -3600T/-3363A/-2984C haplotype is associated with lower promoter activity and appears to impact upon survival in breast cancer patients.