Fibulin-5 inhibits Wnt/β-catenin signaling in lung cancer

Area of Science:

• Oncology
• Molecular Biology
• Extracellular Matrix Biology

Background:

• Metastatic lung cancer is a leading cause of cancer death with unclear invasion mechanisms.
• Fibulin-5, an extracellular matrix protein, was previously identified as a silenced gene and invasion suppressor in lung cancer.

Purpose of the Study:

• To elucidate the molecular mechanism by which fibulin-5 suppresses lung cancer cell invasion.
• To investigate the role of fibulin-5 in the Wnt/β-catenin signaling pathway and its clinical relevance.

Main Methods:

• Analysis of Cancer Genome Atlas (TCGA) datasets for correlations between fibulin-5 expression and patient outcomes.
• In vitro experiments investigating fibulin-5's effect on Wnt/β-catenin signaling, including ERK, GSK3β, β-catenin, MMP-7, and c-Myc.
• In vivo studies using lung cancer xenograft models (H460, H1299, H1752) to assess fibulin-5's role in metastasis.

Main Results:

• Fibulin-5 inhibits Wnt/β-catenin signaling by activating GSK3β, which downregulates β-catenin and suppresses Wnt target genes (MMP-7, c-Myc).
• Loss of fibulin-5 expression in TCGA datasets is associated with poor lung cancer patient outcomes and Wnt pathway activation.
• Fibulin-5 suppresses lung cancer metastasis in vivo, and manipulation of β-catenin or GSK3β levels affects tumor metastasis.

Conclusions:

• Fibulin-5 acts as a metastasis suppressor in lung cancer by inhibiting the Wnt/β-catenin pathway.
• The amino-terminal RGD motif of fibulin-5 is crucial for its anti-metastatic function.
• Targeting the fibulin-5-Wnt/β-catenin axis may offer therapeutic strategies for metastatic lung cancer.