Expression of estrogen receptor alpha exon 5 and 7 deletion variant in human breast cancers.

Abstract

BACKGROUND:

An exon deletion variant of estrogen receptor (ER) mRNA has been reported, as one of the possible mechanisms of loss of ER function.

METHODS:

We examined the expression of exons 3, 5, and 7 in ER alpha mRNA and the frequency of exon deletion variant expression in 64 cases of human breast cancers and in 8 non-cancerous breast tissues using reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS:

Approximately the same amount of wild-type (wt) mRNA was detected in all the non-cancerous breast tissues. In cancers, expression of wild-type exon 3 (w3), exon 5 (w5), and exon 7 (w7) was detected in 93.5%, 93.5%, and 91.3% of ER alpha protein (pER) positive cases, respectively, and 27.8%, 38.9%, and 44.4% in negative cases, respectively (p < 0.0001, p = 0.0035, and p = 0.0002). Although the variants for exon 5 (d5) and 7 (d7) were detected in both non-cancerous and cancerous tissues respectively, the variant for exon 3 was not detected at all. Comparatively, the ratio of d5/w5 was significantly higher in pER positive and progesterone receptor protein (pPgR) negative cases.

CONCLUSIONS:

We suspect that the exon 5 deletion does not work as a dominant positive.

• Authors: Y Omoto, H Iwase, H Iwata, Y Hara, T Toyama, Y Ando, S Kobayashi
• Journal: Breast cancer (Tokyo, Japan) (Breast Cancer) Vol. 7 Issue 1 Pg. 27-31 (Jan 2000) ISSN: 1340-6868 [Print] Japan
• PMID: 11029767 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Estrogen Receptor alpha
• Neoplasm Proteins
• RNA, Messenger
• RNA, Neoplasm
• Receptors, Estrogen

Topics

• Breast (metabolism)
• Breast Neoplasms (genetics, metabolism)
• Carcinoma, Ductal, Breast (metabolism)
• Estrogen Receptor alpha
• Exons (genetics)
• Female
• Gene Expression Regulation, Neoplastic
• Humans
• Neoplasm Proteins (biosynthesis, genetics)
• Polymerase Chain Reaction
• RNA, Messenger (biosynthesis, genetics)
• RNA, Neoplasm (biosynthesis, genetics)
• Receptors, Estrogen (biosynthesis, genetics)
• Sequence Deletion