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1.
Mol Cancer Res ; 21(11): 1148-1162, 2023 11 01.
Article in English | MEDLINE | ID: mdl-37493631

ABSTRACT

PIK3CA is the second most mutated gene in cancer leading to aberrant PI3K/AKT/mTOR signaling and increased translation, proliferation, and survival. Some 4%-25% of gastric cancers display activating PIK3CA mutations, including 80% of Epstein-Barr virus-associated GCs. Small molecules, including pan-PI3K and dual PI3K/mTOR inhibitors, have shown moderate success clinically, due to broad on-target/off-tissue effects. Thus, isoform-specific and mutant selective inhibitors have been of significant interest. However, drug resistance is a problem and has affected success of new drugs. There has been a concerted effort to define mechanisms of resistance and identify potent combinations in many tumor types, though gastric cancer is comparatively understudied. In this study, we identified modulators of the response to the PI3Kα-specific inhibitor, BYL719, in PIK3CA-mutant GCs. We found that loss of NEDD9 or inhibition of BCL-XL conferred hypersensitivity to BYL719, through increased cell-cycle arrest and cell death, respectively. In addition, we discovered that loss of CBFB conferred resistance to BYL719. CBFB loss led to upregulation of the protein kinase PIM1, which can phosphorylate and activate several overlapping downstream substrates as AKT thereby maintaining pathway activity in the presence of PI3Kα inhibition. The addition of a pan-PIM inhibitor re-sensitized resistant cells to BYL719. Our data provide clear mechanistic insights into PI3Kα inhibitor response in PIK3CA-mutant gastric tumors and can inform future work as mutant-selective inhibitors are in development for diverse tumor types. IMPLICATIONS: Loss of either NEDD9 or BCL-XL confers hypersensitivity to PI3K-alpha inhibition whereas loss of CBFB confers resistance through a CBFB/PIM1 signaling axis.


Subject(s)
Epstein-Barr Virus Infections , Stomach Neoplasms , Humans , Stomach Neoplasms/drug therapy , Stomach Neoplasms/genetics , Protein Kinase Inhibitors/pharmacology , Phosphatidylinositol 3-Kinases/genetics , Proto-Oncogene Proteins c-akt/genetics , Cell Line, Tumor , Herpesvirus 4, Human , Phosphoinositide-3 Kinase Inhibitors , Class I Phosphatidylinositol 3-Kinases/genetics , Mutation , Adaptor Proteins, Signal Transducing/genetics
3.
Aging Cell ; 19(2): e13070, 2020 02.
Article in English | MEDLINE | ID: mdl-31777182

ABSTRACT

Dysregulation of autophagy is associated with the neurodegenerative processes in Alzheimer's disease (AD), yet it remains controversial whether autophagy is a cause or consequence of AD. We have previously expressed the full-length human APP in Drosophila and established a fly AD model that exhibits multiple AD-like symptoms. Here we report that depletion of CHIP effectively palliated APP-induced pathological symptoms, including morphological, behavioral, and cognitive defects. Mechanistically, CHIP is required for APP-induced autophagy dysfunction, which promotes Aß production via increased expression of BACE and Psn. Our findings suggest that aberrant autophagy is not only a consequence of abnormal APP activity, but also contributes to dysregulated APP metabolism and subsequent AD pathogenesis.


Subject(s)
Alzheimer Disease/metabolism , Amyloid beta-Protein Precursor/metabolism , Autophagy/genetics , Drosophila Proteins/metabolism , Drosophila/metabolism , Nuclear Proteins/metabolism , Alzheimer Disease/pathology , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/toxicity , Animals , Aspartic Acid Endopeptidases/metabolism , Brain/metabolism , Cognitive Dysfunction/genetics , Disease Models, Animal , Dopaminergic Neurons/metabolism , Down-Regulation , Drosophila Proteins/genetics , Eye/growth & development , Eye/metabolism , Learning Disabilities/genetics , Locomotion/genetics , Longevity/genetics , Nuclear Proteins/genetics , Presenilins/metabolism , RNA Interference , Wings, Animal/metabolism , Wings, Animal/pathology
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