A new perspective on Estrogen Receptor beta in breast cancer progression.

摘要

Breast cancer is a heterogeneous disease with wide-ranging clinical outcomes. According to a report from the American Cancer Society, almost 250,000 American women developed breast cancer in 2009. However, the prognoses for these patients are quite variable. For patients with meta-static breast cancer, the 5 year survival rate is only about 25%. Therefore, extensive basic and clinical research is aimed at differentiating breast cancer patients into subgroups with predictable clinical outcomes. Pathological separation of breast cancers based on tumor grade and stage provides primary information on the disease outcome, but this information falls short of the accurate outcome prediction required in clinics. With the advent of high throughput genetic methods, it is now possible to classify breast cancers based on their genome-wide gene expression profiles. About 10 years ago, DNA microarray analysis of 65 breast samples from 42 individuals classified breast cancers, based on the differential expression of 496 genes, into five subtypes: Luminal A, Luminal B, HER2eu, basal-like and normal breast-like. Luminal A and B breast cancers are ERalpha (Estrogen Receptor alpha) positive and have luminal cell-specific keratin 8/18 expression. HER2eu tumors show highly elevated HER2 oncogene expression due, in some tumors, to genomic amplification of the HER2 locus. ERa expression is usually very low in these HER2eu tumors. Basal-like breast cancers are ERa negative and have characteristic expression of basal myoepithelial cell-specific keratin 5/6.