NOTCH expression variability and relapse of breast cancer in high-risk groups

In regards to breast cancer (BC), survival or disease-free periods are still compromised mainly in Triple Negative (TN) and HER2 tumors. The participation of estrogen receptor (ER) has been reported as crucial in the signaling pathways, including the NOTCH pathway. The study was aimed to evaluate the expression of NOTCH1 and NOTCH3 in BC and its relationship with the presence of ER, as well as with relapses.

NOTCH1 and NOTCH3 expression was evaluated in BC using Oncomine database, Breast Cancer Gene Expression Miner database and Kaplan Meier Plotter. Subsequently, detection of NOTCH1 and NOTCH3 in 100 paraffin-embedded BC samples from Mexican patients was achieved by immunohistochemistry (IHC) and RT-qPCR, a group of benign breast tumors were included as controls. Relapses were evaluated by BC subtypes and their relationship with NOTCH1 and NOTCH3 expression, as well as with ER expression.

The analyses from public databases of TN and HER2 groups, which are estrogen receptor-negative (ERN), revealed NOTCH1 and NOTCH3 expression variability. The overexpression was associated with lower relapse-free survival (P = 0.00019). These data were concordant with results from tumor samples of patients included in this study, which showed overexpression of NOTCH1 and NOTCH3 in ERN tumors, as well as lower relapse-free survival (P < 0.0001).

NOTCH1 and NOTCH3 were found to be overexpressed mainly in ERN tumors. HER2 and TN groups, are related to higher relapse rates. Therefore, anti-NOTCH therapy could be justified and implemented in conventional treatments of high-risk BC groups.