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Robo1/Robo4: differential expression of angiogenic markers in colorectal cancer
Jörn Gröne1, Oliver Doebler, Christoph Loddenkemper
1Department of Surgery, Charité - Medical School Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, D-12200 Berlin, Germany. joern.groene@charite.de
Abstract:
The family of roundabout (Robo) proteins is related to the transmembrane receptors and plays a major role in the process of axonal guidance in neurogenesis. It has recently been shown that Robo proteins are also associated with tumor angiogenesis with Slit2 acting as the corresponding ligand. The aim of this study was to validate the differential expression by means of microarray analysis and real-time PCR and to analyze the in situ expression of Robo1 and Robo4 in colorectal cancer. Quantitative analyses of Robo1, Robo4 and Slit2 mRNA expression measured by large scale gene expression studies (Affymetrix U133A) showed a significant up-regulation of Robo1 in tumor vs. normal tissue, whereas Robo4 and Slit2 showed no significant deregulation. For subsequent real-time PCR experiments, paired colorectal tissue samples from cancerous and corresponding non-cancerous tissues were obtained from 50 colorectal cancer patients who underwent surgical resection. Robo1 mRNA overexpression in cancerous tissue compared with normal counterparts was observed in 80% of the patients with a 4-fold expression in 45% and a 12-fold expression in 15%. For Robo4, an up-regulation was detected in >70% (36/50). For Slit2, no differential expression was observed. The overexpression of Robo1 and Robo4 in tumor vs. normal tissue was verified using real-time PCR. The histological analysis revealed an expression of Robo1 mainly in tumor cells, whereas Robo4 is located primarily in endothelial cells of tumor vessels. Therefore, the Robo proteins provide potential target structures for the anti-tumorigenic and anti-angiogenic therapy of colorectal carcinoma.
Insights
Roundabout (Robo) proteins, Robo1 and Robo4, are overexpressed in colorectal cancer, with Robo1 in tumor cells and Robo4 in endothelial cells, suggesting potential therapeutic targets.
Area of Science:
- Molecular biology
- Oncology
- Neurogenesis
Background:
- Roundabout (Robo) proteins, transmembrane receptors, are crucial for axonal guidance in neurogenesis.
- Robo proteins and their ligand Slit2 are implicated in tumor angiogenesis.
- Colorectal cancer (CRC) presents a significant global health challenge, necessitating novel therapeutic targets.
Purpose of the Study:
- To validate differential expression of Robo1 and Robo4 in colorectal cancer using microarray and real-time PCR.
- To analyze the in situ expression patterns of Robo1 and Robo4 in colorectal tumors.
- To investigate the potential of Robo proteins as therapeutic targets for colorectal carcinoma.
Main Methods:
- Large-scale gene expression studies (Affymetrix U133A) for mRNA expression analysis.
- Real-time quantitative PCR (qPCR) on paired cancerous and non-cancerous colorectal tissue samples from 50 patients.
- Histological analysis to determine the cellular localization of Robo1 and Robo4 expression.
Main Results:
- Microarray analysis revealed significant up-regulation of Robo1 mRNA in tumor versus normal tissue; Robo4 and Slit2 showed no significant deregulation.
- Real-time PCR confirmed Robo1 mRNA overexpression in 80% of CRC patients (4-fold in 45%, 12-fold in 15%) and Robo4 up-regulation in >70% (36/50).
- Robo1 was primarily expressed in tumor cells, while Robo4 was mainly located in the endothelial cells of tumor vessels.
Conclusions:
- Robo1 and Robo4 are overexpressed in colorectal cancer tissues compared to normal counterparts.
- The distinct cellular localization of Robo1 and Robo4 suggests their involvement in tumor growth and angiogenesis.
- Robo proteins represent promising molecular targets for anti-tumorigenic and anti-angiogenic therapies in colorectal carcinoma.
