Distinct apoptotic blocks mediate resistance to panHER inhibitors in HER2+ breast cancer cells

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Chemoresistance is a major challenge in HER2+ breast cancer treatment.
• Neratinib and dacomitinib are irreversible panHER inhibitors targeting HER2 signaling.
• Understanding resistance mechanisms is crucial for improving therapeutic outcomes.

Purpose of the Study:

• To investigate the mechanisms of acquired resistance to neratinib and dacomitinib in HER2+ breast cancer cells.
• To evaluate the predictive value of BH3 profiling for panHER inhibitor resistance.
• To explore combination strategies to overcome acquired resistance.

Main Methods:

• Utilized HER2+ breast cancer cell lines (ZR-75-30, SKBR3, BT474) to study resistance.
• Assessed changes in apoptotic regulatory proteins (MCL1, BIM, PUMA, BCL-XL, BCL-2).
• Employed BH3 profiling to predict antiapoptotic protein dependence.
• Investigated the role of ERK1/2 reactivation and tested combination therapies (ERK1/2 inhibitors, ABT-737).

Main Results:

• Distinct apoptotic protein alterations (MCL1, BCL-XL, BCL-2) mediated neratinib resistance in different cell lines.
• Cells exhibited cross-resistance to dacomitinib.
• BH3 profiling accurately predicted resistance mechanisms.
• ERK1/2 reactivation was a key resistance driver in SKBR3 and ZR-75-30 cells.
• Combination therapy with ERK1/2 inhibitors improved apoptosis in resistant cells, with additional BCL-2/BCL-XL inhibition needed for BT474 cells.

Conclusions:

• Acquired resistance to panHER inhibitors in HER2+ breast cancer involves diverse mitochondrial apoptotic pathway dysregulation.
• BH3 profiling is a valuable tool for predicting and guiding treatment strategies against panHER inhibitor resistance.
• Targeting ERK1/2 and specific antiapoptotic proteins offers potential therapeutic avenues to overcome resistance.