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Updated: May 30, 2025

Assessing Cellular Target Engagement by SHP2 PTPN11 Phosphatase Inhibitors
Published on: July 17, 2020
Dual targeting PPARα and NPC1L1 metabolic vulnerabilities blocks tumorigenesis
Xiaona You1, Xi Hu2, Zenghui Sun2
1Advanced Medical Research Institute, Cheeloo College of Medicine, Shandong University, Jinan, 250012, China; School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, China.
Abstract:
Dysregulated lipid metabolism is linked to tumor progression. In this study, we identified Niemann-Pick C1-like 1 (NPC1L1) as a downstream effector of PKM2. In breast cancer cells, PKM2 knockout (KO) enhanced NPC1L1 expression while downregulating peroxisome proliferator-activated receptor α (PPARα) signaling pathway. PPARα and nuclear factor-E2 p45-related factor 1/2(Nrf1/2) are transcription factors regulating NPC1L1. In vitro PKM2 KO enhanced recruitment of Nrf1/2 to the NPC1L1 promoter region. Fenofibrate, a PPARα activator, promoted NPC1L1 expression; ezetimibe, an NPC1L1 inhibitor and effective Nrf2 activator, also elevated NPC1L1 expression. Combined administration of fenofibrate and ezetimibe significantly induced cytoplasmic vacuolation, and cell apoptosis. Mechanistically, this combined administration activated inositol required enzyme 1α(IRE1α) and produced the spliced form of X-box binding protein (XBP1s), which in turn enhanced lysine demethylase 6B (KDM6B) transcription. XBP1s interacts with KDM6B to activate genes involved in the unfolded protein response by demethylating di- and tri-methylated lysine 27 of histone H3 (H3K27), consequently increasing H3K27 acetylation levels in breast cancer cell lines. Fenofibrate and ezetimibe synergistically inhibited tumor growth in vivo. Our findings reveal that dual targeting of PPARα and NPC1L1 may represent a novel therapeutic regimen for breast cancer therapy.
Insights
Targeting lipid metabolism in breast cancer, this study found that inhibiting Niemann-Pick C1-like 1 (NPC1L1) alongside activating peroxisome proliferator-activated receptor α (PPARα) induced cancer cell death and suppressed tumor growth.
Area of Science:
- Oncology
- Molecular Biology
- Metabolic Pathways
Background:
- Dysregulated lipid metabolism is a hallmark of cancer, influencing tumor progression.
- PKM2 (Pyruvate Kinase M2) plays a role in cancer metabolism, but its downstream effectors are not fully understood.
- Niemann-Pick C1-like 1 (NPC1L1) is involved in cholesterol absorption and its role in cancer is emerging.
Purpose of the Study:
- To investigate the role of NPC1L1 as a downstream target of PKM2 in breast cancer.
- To explore the therapeutic potential of targeting NPC1L1 and PPARα signaling in breast cancer.
Main Methods:
- Utilized PKM2 knockout (KO) breast cancer cell models.
- Investigated the effects of fenofibrate (PPARα activator) and ezetimibe (NPC1L1 inhibitor) on cell apoptosis and tumor growth.
- Analyzed molecular mechanisms including transcription factor recruitment, IRE1α/XBP1s pathway activation, and histone modifications (H3K27 demethylation).
Main Results:
- PKM2 KO enhanced NPC1L1 expression and downregulated PPARα signaling.
- Fenofibrate and ezetimibe synergistically induced breast cancer cell apoptosis via IRE1α/XBP1s/KDM6B pathway activation and H3K27 acetylation.
- Combined treatment significantly inhibited tumor growth in vivo.
Conclusions:
- NPC1L1 is a downstream effector of PKM2 in breast cancer.
- Dual targeting of PPARα and NPC1L1 presents a promising novel therapeutic strategy for breast cancer.
- The IRE1α/XBP1s/KDM6B axis mediates the anti-cancer effects of combined fenofibrate and ezetimibe treatment.
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