Oestrogen receptor-related receptor alpha (ERR alpha) and oestrogen receptors (ER alpha and ER beta) exhibit different gene expression in human colonrectal 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. ERRa was found in 100% of the patients and ERRc in approximately 30% while ERRb was not detected at all. The multiplex PCR analysis showed elevated levels of ERRa mRNA in tumour tissue compartment as compared to normal mucosa, whereas ERRc mRNA was found in lower levels but in both tissue compartments. In contrast, oestrogen receptor (ERa and ERb) mRNA levels were shown to be decreased in tumour tissues. A positive correlation was observed between ERa and ERb and between ERa and ERRa, respectively, in normal mucosa but not in tumour tissue. ERRa expression in tumour tissues significantly increased from TNM stages II to IV, whereas both ERs progressively declined. These findings suggest that ERRa, as well as the two ERs, might play a critical role in the progression of the colorectal cancer.