Oestrogen receptor-related receptor alpha (ERRα) and oestrogen receptors (ERα and ERβ) exhibit different gene expression in human colorectal tumour progression

We have investigated the presence of oestrogen receptor-related (ERR) mRNA in human colorectal tumour tissues and adjacent normal mucosa by reverse transcriptase and nested-polymerase chain reaction. ERR alpha was found in 100% of the patients and ERR gamma in approximately 30% while ERR beta was not detected at all. The multiplex PCR analysis showed elevated levels of ERR alpha mRNA in tumour tissue compartment as compared to normal mucosa, whereas ERR gamma mRNA was found in lower levels but in both tissue compartments. In contrast, oestrogen receptor (ER alpha and ER beta) mRNA levels were shown to be decreased in tumour tissues. A positive correlation was observed between ER alpha and ER beta and between ER alpha and ERR alpha, respectively, in normal mucosa but not in tumour tissue. ERR alpha expression in tumour tissues significantly increased from TNM stages II to IV, whereas both ERs progressively declined. These findings suggest that ERR alpha, as well as the two ERs, might play a critical role in the progression of the colorectal cancer. (c) 2005 Elsevier Ltd. All rights reserved.