Hamster estrogen receptor cDNA: cloning and mRNA expression

Estrogen-induced hamster kidney tumor model serves as a useful model to study the biochemical and molecular mechanisms of hormonal carcinogenesis. In this model, we have demonstrated an increased expression of estrogen receptor mRNA and protein in estrogen-treated kidneys and in estrogen-induced tumors. The sequence information for hamster estrogen receptor gene is not known and has been investigated in this study. A hamster uterus cDNA library was constructed and the 5'-region of the hamster estrogen receptor cDNA cloned from this library using polymerase chain reaction (PCR) methodology. Additionally, hamster kidney polyadenylated RNA was reverse transcribed and PCR amplified using primers that were designed based on maximum homology between mouse, rat and human estrogen receptor cDNAs. These PCR amplified fragments were cloned into plasmid vectors and clones with the expected size of the insert subjected to Southern blot analysis using human estrogen receptor cDNA as a probe. The positive clones on Southern blot analysis and the PCR amplified products from these clones were subjected to DNA sequence analysis. Using this strategy, a full length, 1978 bp hamster estrogen receptor cDNA has been cloned which shows 87% homology with human, 90% with rat and 91% with mouse estrogen receptor cDNA. The deduced amino acid shares 88% homology with human, and 93% with rat and mouse estrogen receptors. Hamster estrogen receptor domain C (DNA binding domain) shows a 100% homology with a similar domain from mouse, rat, human, pig, sheep, horse and chicken estrogen receptor (Genebank reference ID: AF 181077).