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XAF1 forms a positive feedback loop with IRF-1 to drive apoptotic stress response and suppress tumorigenesis

Seong-In Jeong1, Jung-Wook Kim2, Kyung-Phil Ko1

  • 1Department of Life Sciences, Korea University, Seoul, 02841, Korea.

Cell Death & Disease
|July 26, 2018
PubMed

Insights

X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) acts as a tumor suppressor by forming a positive feedback loop with interferon regulatory factor-1 (IRF-1). This interaction enhances apoptosis and reduces tumor cell invasion, revealing a novel cancer suppression mechanism.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cellular Signaling

Background:

  • X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) is a known tumor suppressor frequently inactivated in human cancers.
  • The precise molecular mechanisms underlying XAF1's tumor-suppressive functions, particularly its role in growth inhibition, are not fully understood.

Purpose of the Study:

  • To elucidate the molecular basis of XAF1-mediated tumor suppression.
  • To investigate the relationship between XAF1 and interferon regulatory factor-1 (IRF-1) in cancer.
  • To identify how oncogenic pathways interfere with XAF1 function.

Main Methods:

  • Investigated the interaction between XAF1 and IRF-1 using molecular biology techniques.
  • Analyzed the effect of the XAF1-IRF-1 feedback loop on apoptosis and tumor cell invasion.
  • Examined the role of Erk signaling in regulating XAF1 transcription.
  • Assessed the correlation between IRF-1 and XAF1 expression in cancer cells and tumors.

Main Results:

  • XAF1 forms a positive feedback loop with IRF-1, enhancing IRF-1 stability and transcriptional activity.
  • XAF1 acts as a coactivator for IRF-1, promoting stress-induced apoptosis and reducing tumor cell invasiveness.
  • Oncogenic Ras and growth factors inhibit the XAF1-IRF-1 loop via Erk-mediated repression of XAF1 transcription.
  • XAF1 enhances IRF-1-mediated transcription of proapoptotic genes and inhibits NF-κB signaling.

Conclusions:

  • XAF1 functions as a crucial transcriptional coactivator of IRF-1, establishing a feedback loop that suppresses tumorigenesis.
  • The IRF-1-XAF1 axis represents a novel therapeutic target for cancer treatment.
  • Understanding this interplay is key to developing strategies against cancers with inactivated XAF1.

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