Classification of PR-positive and PR-negative subtypes in ER-positive and HER2-negative breast cancers based on pathway scores

Purpose PR loss in ER+/HER2- breast cancer indicates worse prognosis and insensitivity to anti-estrogen therapy, while the mechanisms of PR loss in ER+/HER2- breast cancer remain unrevealed. Methods In this study, ER+/PR+/HER2- and ER+/PR-/HER2- breast cancer cases from TCGA were used. 1387 pathways were analyzed and used as variables for classifying the two groups with LASSO regression. Results ER+/PR+/HER2- and ER+/PR-/HER2- breast cancer groups can be classified by a combination of 13 pathways using their activity score. Among the 13 pathways, those involving growth factors and ion-channel transporters were most significant in the distinction, followed by pathways involving immune modulation and cell metabolism. Two growth factor pathways, EGF and IGF-1, were deferentially regulated in ER+/PR+/HER2- and ER+/PR-/HER2- groups. Conclusions In conclusion, this study indicated in ER+/HER2- breast cancers the various status of PR expression can be an indication of molecular variation, particularly for the growth factor pathway activation.

Automated summary

The loss of PR expression in ER+/HER2- breast cancers indicates a worse prognosis and insensitivity to anti-estrogen therapy. Various PR expression statuses in these cancers can be indicative of molecular variation, particularly in relation to the activation of growth factor pathways.