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Oncogene DOI:10.1038/onc.2014.153

PRKACA mediates resistance to HER2-targeted therapy in breast cancer cells and restores anti-apoptotic signaling.

Publication TypeJournal Article
Year of Publication2015
AuthorsMoody, SE, Schinzel, AC, Singh, S, Izzo, F, Strickland, MR, Luo, L, Thomas, SR, Boehm, JS, Kim, SY, Wang, ZC, Hahn, WC
Date Published2015 Apr 16
KeywordsAntibodies, Monoclonal, Humanized, Antineoplastic Agents, Apoptosis, bcl-Associated Death Protein, bcl-X Protein, Breast Neoplasms, Cyclic AMP-Dependent Protein Kinase Catalytic Subunits, Drug Resistance, Neoplasm, Female, Gene Expression Profiling, HEK293 Cells, Humans, Mitogen-Activated Protein Kinases, Open Reading Frames, Phosphatidylinositol 3-Kinases, Phosphorylation, Protein Kinase Inhibitors, Proto-Oncogene Proteins c-pim-1, Quinazolines, Receptor, ErbB-2, Trastuzumab

Targeting HER2 with antibodies or small molecule inhibitors in HER2-positive breast cancer leads to improved survival, but resistance is a common clinical problem. To uncover novel mechanisms of resistance to anti-HER2 therapy in breast cancer, we performed a kinase open reading frame screen to identify genes that rescue HER2-amplified breast cancer cells from HER2 inhibition or suppression. In addition to multiple members of the MAPK (mitogen-activated protein kinase) and PI3K (phosphoinositide 3-kinase) signaling pathways, we discovered that expression of the survival kinases PRKACA and PIM1 rescued cells from anti-HER2 therapy. Furthermore, we observed elevated PRKACA expression in trastuzumab-resistant breast cancer samples, indicating that this pathway is activated in breast cancers that are clinically resistant to trastuzumab-containing therapy. We found that neither PRKACA nor PIM1 restored MAPK or PI3K activation after lapatinib or trastuzumab treatment, but rather inactivated the pro-apoptotic protein BAD, the BCl-2-associated death promoter, thereby permitting survival signaling through BCL-XL. Pharmacological blockade of BCL-XL/BCL-2 partially abrogated the rescue effects conferred by PRKACA and PIM1, and sensitized cells to lapatinib treatment. These observations suggest that combined targeting of HER2 and the BCL-XL/BCL-2 anti-apoptotic pathway may increase responses to anti-HER2 therapy in breast cancer and decrease the emergence of resistant disease.


Alternate JournalOncogene
PubMed ID24909179
PubMed Central IDPMC4261061
Grant ListR01 CA130988 / CA / NCI NIH HHS / United States
U01 CA176058 / CA / NCI NIH HHS / United States
U54 CA112962 / CA / NCI NIH HHS / United States