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. ERRα was found in 100% of the patients and ERRγ in approximately 30% while ERRβ was not detected at all. The multiplex PCR analysis showed elevated levels of ERRα mRNA in tumour tissue compartment as compared to normal mucosa, whereas ERRγ mRNA was found in lower levels but in both tissue compartments. In contrast, oestrogen receptor (ERα and ERβ) mRNA levels were shown to be decreased in tumour tissues. A positive correlation was observed between ERα and ERβ and between ERα and ERRα, respectively, in normal mucosa but not in tumour tissue. ERRα expression in tumour tissues significantly increased from TNM stages II to IV, whereas both ERs progressively declined. These findings suggest that ERRα, as well as the two ERs, might play a critical role in the progression of the colorectal cancer.