Quantitative analysis of estrogen receptor-beta mRNA and its variants in human breast cancers

We have carried out a quantitative analysis of ER-alpha and ER-beta mRNA ex pression in normal (n = 11) and breast cancer (n = 112) tissues using a rea l-time (Taq-Man) PCR assay. Expression of ER-beta mRNA variants has also be en studied by triple-primer PCR assay. ER-alpha mRNA levels in normal breas t tissues were significantly (p < 0.01) lower than those in ER-positive bre ast cancers but not significantly different from those in ER-negative breas t cancers. However, ER-<beta> mRNA levels in normal breast tissues were sig nificantly (p < 0.01) higher than those in ER-positive and ER-negative brea st cancers. Proportions of ER-<beta>1 and ER-beta2 mRNA expression among to tal ER-beta mRNA expression were significantly higher and those of ER-beta5 and ER-beta5' mRNA were significantly lower in normal breast tissues than in ER-positive and ER-negative breast cancers. ER-beta mRNA levels and prop ortions of ER-beta mRNA variants did not show any significant correlation w ith age, tumor size, lymph node status and histological grade. Our results demonstrate that ER-alpha mRNA is up-regulated and ER-alpha mRNA is down-re gulated during carcinogenesis of breast cancers. Changes in proportions of ER-beta mRNA variants are also implicated in this process. (C) 2000 Wiley-L iss, me.