SOX4 expression in bladder carcinoma: clinical aspects and in vitro functional characterization

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• SOX4 (SRY-box transcription factor 4) is a human transcription factor.
• Whole-genome expression profiling revealed a 5-fold upregulation of SOX4 in bladder tumors compared to normal urothelium.

Purpose of the Study:

• To evaluate SOX4 protein expression in a large cohort of bladder tumors.
• To investigate the correlation between SOX4 expression and patient survival.
• To identify SOX4-regulated genes and pathways in bladder cancer.

Main Methods:

• Whole-genome expression profiling of 166 bladder tumors and 27 normal samples.
• Immunohistochemical analysis of SOX4 protein expression in 2,360 bladder tumors using tissue microarrays.
• In vitro studies involving SOX4 overexpression in the HU609 bladder cell line and time-course global expression analysis.
• Bioinformatic analysis to identify SOX4-binding motifs and downstream target genes.

Main Results:

• Strong SOX4 protein expression was observed in bladder cancer cells and correlated significantly with increased patient survival (P < 0.05).
• Overexpression of SOX4 in vitro impaired cell viability and promoted apoptosis.
• 130 novel SOX4-related genes were identified, including those involved in signal transduction (MAP2K5), angiogenesis (NRP2), and cell cycle arrest (PIK3R3).
• Direct binding of SOX4 was suggested for 25 regulated genes containing SOX4-binding motifs.

Conclusions:

• SOX4 is upregulated in bladder cancer and its expression is linked to improved patient outcomes.
• SOX4 influences critical cellular processes, including cell viability, apoptosis, signal transduction, angiogenesis, and cell cycle regulation.
• These findings suggest a significant role for SOX4 in the pathogenesis and progression of bladder cancer.