Introduction:
Studies show that the development of endometrial cancer is associated with the activity of estrogen-dependent genes, whose action is conditioned by the presence of estrogen receptors (ER). Analysis of the transcriptional activity of the genes which code ERs as well as the concentration profile of their isoforms could help to understand the mechanism of estrogen activity on the risk of endometrial cancer occurrence, as well as the mechanisms involved in its development and spread. The aim of the conducted studies was to compare the transcriptional activity of the genes coding ER-alpha and ER-beta estrogen receptors, determine the types of post-transcription modifications of ER mRNA in endometrial adenocarcinoma and normal endometrium as well as determine the transcriptome of estrogen-dependent genes of cytochrome P450.

Material and methods:
Extraction of the total RNA from 47 endometrium samples was performed with the TRIzol reagent (Invitrogen). The expression profile of the estrogen-dependent genes of cytochrome P450 was determined using the HG-U133A (Affymetrix) oligonucleotide microarray technique from among 22,283 IDs of mRNA IDs. The QRT-PCR reaction for quantification of the mRNA of estrogen receptors was performed using an ABI PRISMTM 7700 (TaqMan) sequence detector. For the QRT-PCR reaction, oligonucleotide starter sequences to detect the ER-alpha and ER-beta mRNA isoforms were designed using Primer ExpressTM Version 1.0 software.

Results:
In the presented work, it was found that estrogen receptor gene expression occurs in normal endometrium as well as in endometrial adenocarcinoma, and the dominating type is ER-alpha. The transcriptional activity of the ER-alpha and ER-beta genes decreases in adenocarcinoma with a simultaneous increase in the transcriptional activity ratio. The ER-alpha/delta5 isoform dominates in endometrial cancer. Statistical analysis conducted in the GeneSpring 11.5 programme showed that from the group of 91 mRNA IDs of the genes of cytochrome P450, 5 mRNA IDs differentiate, for p <0.5 and FC(log2) > 1.5. In the presented work, it was found that the expression of estrogen receptor genes occurs in normal endometrium and endometrial adenocarcinoma, and the dominant type is ER-alpha. The transcriptional activity of the ER-alpha and ER-beta genes decreases in adenocarcinoma, while the transcriptional activity index increases. In endometrial cancer, the ER-alpha/delta5 isoform dominates. Statistical analysis conducted in GeneSpring 11.5 showed that from the group 91 ID mRNA of cytochrome P450 genes, 5 ID mRNA is differentiating, for p < 0.5 and FC (log2) > 1.5.

Conclusions:
The presence of such a transcriptional profile of the studied genes in endometrial adenocarcinoma may indicate that post-transcriptional modifications of estrogen receptors are associated with changes triggering carcinogenesis.