Susceptibility to prostate or endometrial cancer is linked with obesity, a state of oestrogen excess. Oestrogen receptor (ER) splice variants may be responsible for the tissue-level of ER activity. Such micro-environmental regulation may modulate cancer initiation and/or progression mechanisms. Real-time reverse transcriptase (RT) polymerase chain reaction (PCR) was used to quantitatively assess the levels of four ER splice variants ( ER α Δ 3, ER α Δ 5, ER β2 and ER β 5), plus the full-length parent isoforms ER α and ER β 1, in high-risk [tumour-adjacent prostate ( n = 10) or endometrial cancer ( n = 9)] vs. low-risk [benign prostate ( n = 12) or endometrium ( n = 9)], as well as a comparison of UK ( n = 12) vs. Indian ( n = 15) benign prostate. All three tissue groups expressed the ER splice variants at similar levels, apart from ER α Δ 5. This splice variant was markedly raised in all of the tumour-adjacent prostate samples compared to benign tissues. Immunofluorescence analysis for ER β2 in prostate tissue demonstrated that such splice variants are present in comparable, if not greater, amounts as the parent full-length isoform. This small pilot study demonstrates the ubiquitous nature of ER splice variants in these tissue sites and suggests that ER α Δ5 may be involved in progression of prostate adenocarcinoma.
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