Quantitative analysis of estrogen receptor-alpha and -beta messenger RNA expression in breast carcinoma by real-time polymerase chain reaction.

Kyoko Iwao,Shinzaburo Noguchi,Yasuo Miyoshi,Fumine Tsukamoto,Noriko Ikeda,Chiyomi Egawa

doi:10.1002/1097-0142(20001015)89:8<1732::aid-cncr13>3.0.co;2-2

Kyoko Iwao, Shinzaburo Noguchi + Show 4 more

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https://doi.org/10.1002/1097-0142(20001015)89:8<1732::aid-cncr13>3.0.co;2-2

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Journal: Cancer	Publication Date: Oct 15, 2000
Citations: 89

Affiliation: Osaka University, GTx (United States)

Abstract

Estrogen action is mediated not only through a classic estrogen receptor (ER) (ER-alpha) but also through a second ER (ER-beta) that has a structure and function similar to ER-alpha. A correlation between ER-beta mRNA expression with ER and progesterone receptor (PR) protein levels as well as prognostic factors remains to be established in breast carcinoma. The authors conducted a quantitative analysis of ER-alpha and ER-beta mRNA expression in 116 breast tumors using real-time polymerase chain reaction (PCR), and investigated a possible correlation between ER-alpha and ER-beta mRNA expression and ER and PR status as determined by enzyme immunoassay as well as with various prognostic factors. ER-alpha mRNA levels were significantly (P < 0.01) higher in ER positive compared with ER negative tumors. Conversely, ER-beta mRNA levels were significantly (P < 0.01) lower in ER positive compared with ER negative tumors. Accordingly, the ratio of ER-beta to ER-alpha was significantly (P < 0.01) higher in ER negative compared with ER positive tumors. A subset analysis based on ER and PR status showed that ER-beta mRNA levels as well as the ratios of ER-beta to ER-alpha mRNA level were highest in ER negative and PR negative tumors (P < 0.05). ER-alpha mRNA levels were significantly (P < 0.05) higher in postmenopausal compared with premenopausal tumors. Histologic Grade 3 tumors showed a significant decrease in ER-alpha mRNA levels compared with Grade 1 and 2 tumors (P < 0.01 and P < 0.05, respectively). No significant correlation between ER-alpha and ER-beta mRNA levels and histologic type, tumor size, or lymph node status was observed. An absolute and relative increase in ER-beta mRNA levels in ER negative and PR negative breast tumors, which rarely respond to endocrine therapy, suggests the possible involvement of up-regulation of ER-beta mRNA in the development of estrogen-independent tumors.

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