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Quantitative analysis of estrogen receptor‐α and ‐β messenger RNA expression in breast carcinoma by real‐time polymerase chain reaction
Author(s) -
Iwao Kyoko,
Miyoshi Yasuo,
Egawa Chiyomi,
Ikeda Noriko,
Tsukamoto Fumine,
Noguchi Shinzaburo
Publication year - 2000
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/1097-0142(20001015)89:8<1732::aid-cncr13>3.0.co;2-2
Subject(s) - estrogen receptor alpha , estrogen receptor , messenger rna , estrogen receptor beta , estrogen , medicine , endocrinology , beta (programming language) , alpha (finance) , real time polymerase chain reaction , receptor , breast cancer , biology , cancer , gene , biochemistry , construct validity , nursing , computer science , patient satisfaction , programming language
BACKGROUND Estrogen action is mediated not only through a classic estrogen receptor (ER) (ER‐α) but also through a second ER (ER‐β) that has a structure and function similar to ER‐α. A correlation between ER‐β mRNA expression with ER and progesterone receptor (PR) protein levels as well as prognostic factors remains to be established in breast carcinoma. METHODS The authors conducted a quantitative analysis of ER‐α and ER‐β mRNA expression in 116 breast tumors using real‐time polymerase chain reaction (PCR), and investigated a possible correlation between ER‐α and ER‐β mRNA expression and ER and PR status as determined by enzyme immunoassay as well as with various prognostic factors. RESULTS ER‐α mRNA levels were significantly ( P < 0.01) higher in ER positive compared with ER negative tumors. Conversely, ER‐β mRNA levels were significantly ( P < 0.01) lower in ER positive compared with ER negative tumors. Accordingly, the ratio of ER‐β to ER‐α 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‐β mRNA levels as well as the ratios of ER‐β to ER‐α mRNA level were highest in ER negative and PR negative tumors ( P < 0.05). ER‐α mRNA levels were significantly ( P < 0.05) higher in postmenopausal compared with premenopausal tumors. Histologic Grade 3 tumors showed a significant decrease in ER‐α mRNA levels compared with Grade 1 and 2 tumors ( P < 0.01 and P < 0.05, respectively). No significant correlation between ER‐α and ER‐β mRNA levels and histologic type, tumor size, or lymph node status was observed. CONCLUSIONS An absolute and relative increase in ER‐β 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‐β mRNA in the development of estrogen‐independent tumors. Cancer 2000;89:1732–8. © 2000 American Cancer Society.