Classification of breast cancer into molecular subtypes may be important for the proper selection of therapy, as tumors with seemingly similar biology can have strikingly different clinical outcomes. We have previously developed an 80-gene molecular subtyping profile (BluePrint) for the classification of breast cancer into three molecular subtypes: triplenegative (“Basal-type”); hormone receptor-positive (“Luminal-type”) and ERBB2 positive (“ERBB2-type”). In this study, we sought to determine if Luminal-type tumors are characterized by active ER signaling.
– Luminal-type associated genes are enriched for ER binding sites proximal to the transcription start site, suggesting that these genes are direct targets of ER.
– Classification of breast tumors as “Luminal” by BluePrint most likely describes breast cancers that depend of ER signaling.
– This data suggests that Luminal-type breast cancer are likely to response to endocrine therapy.