Hypoxia Promotes Syndecan-3 Expression in the Tumor Microenvironment

Area of Science:

• Cell biology
• Oncology
• Molecular biology

Background:

• Syndecan-3 (Sdc-3) is a cell surface molecule crucial for development and cell adhesion.
• While Sdc-3's role in inflammation is known, its significance in cancer is unexplored.
• Sdc-3 expression patterns and functions in various cancer types require investigation.

Purpose of the Study:

• To investigate the expression patterns and significance of Syndecan-3 (Sdc-3) in cancer.
• To determine the relationship between Sdc-3 expression, tumor hypoxia, and the tumor microenvironment.
• To explore the impact of Sdc-3 expression on patient survival in hypoxic tumors.

Main Methods:

• Analysis of Cancer Genome Atlas (TCGA) data for Sdc-3 expression and hypoxia correlation.
• In vitro experiments exposing tumor cell lines to hypoxia (1% oxygen) and dimethyloxalylglycine.
• CRISPR engineering to confirm HIF-1α's role in Sdc-3 upregulation.
• Single-cell RNA sequencing analysis of melanoma patient data.
• In vitro experiments with macrophages (RAW-264.7) under hypoxia and IFN-γ stimulation.

Main Results:

• Sdc-3 expression is upregulated in multiple cancer types, particularly in solid tumors with hypoxia.
• TCGA data shows a positive correlation between Sdc-3 expression and hypoxia gene signatures.
• Hypoxia and HIFs, specifically HIF-1α, were confirmed to promote Sdc-3 expression.
• Sdc-3 is expressed on cancer cells, macrophages, and endothelial cells in melanoma.
• Sdc-3 expression correlates positively with macrophage signatures and better overall survival in hypoxic melanoma.

Conclusions:

• Hypoxia is a key regulator of Syndecan-3 (Sdc-3) expression in cancer via HIFs.
• Sdc-3 is implicated in the tumor microenvironment, involving cancer cells and tumor-associated macrophages.
• Sdc-3 expression may serve as a predictive biomarker for improved patient survival in hypoxic melanoma.