Presence of alternatively spliced transcripts of aromatase gene in human breast cancer

J Clin Endocrinol Metab. 1996 Jun;81(6):2344-9. doi: 10.1210/jcem.81.6.8964875.


The expression of aromatase (estrogen synthetase) is tissue specifically regulated through the alternative use of multiple exons 1 and promotors. We have determined the amounts of aromatase messenger ribonucleic acid (mRNA) and which type of multiple exons 1 of the human aromatase gene is used in breast tissues of 49 patients with breast cancer by reverse transcription-PCR analysis. The aromatase mRNA levels in these breast cancer tissues (4.53 +/- 0.66 x 10(-3) attomoles/micrograms RNA) were significantly (P < 0.01) higher than those in 16 nonmalignant breast tissues (1.73 +/- 0.40 x 10(-3) amol/micrograms RNA). Aromatase mRNA in all nonmalignant breast tissue were transcribed from skin fibroblast/fetal liver-specific exon 1 (exon 1b) of the gene. In 23 breast cancer tissues, the utilization of multiple exons 1 in the aromatase mRNA was the same as that in nonmalignant breast tissues, whereas in the other 26 cases, it changed from exon 1b to ovary-specific exon 1 (exon 1c). Such switching of tissue-specific exons 1 may affect strict regulation of the tissue-specific expression of aromatase, leading to abnormal expression of the aromatase. The consequent overproduction of local estrogen might promote carcinogenesis or the proliferation of breast cancers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Alternative Splicing*
  • Aromatase / genetics*
  • Base Sequence
  • Breast Neoplasms / chemistry
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology
  • Exons
  • Female
  • Genes*
  • Humans
  • Immunochemistry / methods
  • Middle Aged
  • Molecular Sequence Data
  • Oligonucleotide Probes / genetics
  • RNA, Messenger / analysis
  • RNA, Messenger / genetics
  • Transcription, Genetic*


  • Oligonucleotide Probes
  • RNA, Messenger
  • Aromatase