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FAM129B, an antioxidative protein, reduces chemosensitivity by competing with Nrf2 for Keap1 binding
Kai-Chun Cheng1, Ruey-Jen Lin2, Jing-Yan Cheng2
1Institute of Stem Cell & Translational Cancer Research, Chang Gung Memorial Hospital at Linkou, Chang Gung University, Taoyuan, Taiwan; Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan.
Background:
The transcription factor Nrf2 is a master regulator of antioxidant response. While Nrf2 activation may counter increasing oxidative stress in aging, its activation in cancer can promote cancer progression and metastasis, and confer resistance to chemotherapy and radiotherapy. Thus, Nrf2 has been considered as a key pharmacological target. Unfortunately, there are no specific Nrf2 inhibitors for therapeutic application. Moreover, high Nrf2 activity in many tumors without Keap1 or Nrf2 mutations suggests that alternative mechanisms of Nrf2 regulation exist.
Methods:
Interaction of FAM129B with Keap1 is demonstrated by immunofluorescence, colocalization, co-immunoprecipitation and mammalian two-hybrid assay. Antioxidative function of FAM129B is analyzed by measuring ROS levels with DCF/flow cytometry, Nrf2 activation using luciferase reporter assay and determination of downstream gene expression by qPCR and wester blotting. Impact of FAM129B on in vivo chemosensitivity is examined in mice bearing breast and colon cancer xenografts. The clinical relevance of FAM129B is assessed by qPCR in breast cancer samples and data mining of publicly available databases.
Findings:
We have demonstrated that FAM129B in cancer promotes Nrf2 activity by reducing its ubiquitination through competition with Nrf2 for Keap1 binding via its DLG and ETGE motifs. In addition, FAM129B reduces chemosensitivity by augmenting Nrf2 antioxidative signaling and confers poor prognosis in breast and lung cancer.
Interpretation:
These findings demonstrate the important role of FAM129B in Nrf2 activation and antioxidative response, and identify FMA129B as a potential therapeutic target. FUND: The Chang Gung Medical Foundation (Taiwan) and the Ministry of Science and Technology (Taiwan).
Insights
FAM129B protein enhances cancer cell survival by activating the Nrf2 pathway, promoting resistance to chemotherapy and indicating a poor prognosis in breast and lung cancers. This identifies FAM129B as a potential therapeutic target.
Area of Science:
- Molecular Biology
- Cancer Research
- Biochemistry
Background:
- Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator of the antioxidant response.
- While Nrf2 activation can be protective against aging-related oxidative stress, its upregulation in cancer promotes tumor progression, metastasis, and treatment resistance.
- Existing therapeutic strategies lack specific Nrf2 inhibitors, and alternative regulatory mechanisms are suggested by high Nrf2 activity in tumors lacking Keap1 or Nrf2 mutations.
Purpose of the Study:
- To investigate the role of FAM129B in regulating Nrf2 activity in cancer.
- To determine the impact of FAM129B on cancer cell chemosensitivity and patient prognosis.
- To explore FAM129B as a potential therapeutic target for cancer treatment.
Main Methods:
- Interaction between FAM129B and Keap1 was confirmed using immunofluorescence, colocalization, co-immunoprecipitation, and mammalian two-hybrid assays.
- Antioxidant function was assessed by measuring reactive oxygen species (ROS) levels, Nrf2 activation via luciferase reporter assays, and downstream gene expression.
- In vivo chemosensitivity was evaluated in mouse xenograft models, and clinical relevance was assessed through qPCR and public database mining.
Main Results:
- FAM129B promotes Nrf2 activity in cancer by competing with Nrf2 for Keap1 binding, thereby reducing Nrf2 ubiquitination.
- FAM129B enhances Nrf2-mediated antioxidative signaling, leading to decreased chemosensitivity in cancer cells.
- Increased FAM129B expression correlates with a poor prognosis in breast and lung cancer patients.
Conclusions:
- FAM129B plays a significant role in activating the Nrf2 pathway and promoting antioxidative responses in cancer.
- FAM129B's function in enhancing Nrf2 activity and conferring treatment resistance positions it as a potential therapeutic target for cancer intervention.
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