Co-expression of receptor tyrosine kinases in esophageal adenocarcinoma and squamous cell cancer

This study aimed to define the co-expression pattern of target receptor tyrosine kinases (RTKs) in human esophageal adenocarcinoma and squamous cell cancer. The co-expression pattern of vascular endothelial growth factor receptor (VEGFR)1-3, platelet-derived growth factor receptor (PDGFR)α/β and epidermal growth factor receptor 1 (EGFR1) was analyzed by RT-PCR in 50 human esophageal cancers (35 adenocarcinomas and 15 squamous cell cancers). In addition, IHC staining was applied for the confirmation of the expression and analysis of RTK localisation. The adenocarcinoma samples revealed VEGFRI (97%), VEGFR2 (94%), VEGFR3 (77%), PDGFRa (91%), PDGFRβ (85%) and EGFR1 (97%) expression at different intensities. Ninety-four percent of the esophageal adenocarcinomas expressed at least four out of six RTKs. Similarly, squamous cell cancers revealed VEGFR1 (100%), VEGFR2 (100%), VEGFR3 (53%), PDGFRa (100%), PDGFRβ (87%) and EGFR1 (100%) expression at different intensities. All esophageal squamous cell carcinomas expressed at least four out of six RTKs. While VEGFRI-3 and PDGFRa and EGFR1 was expressed by tumor cells, PDGFRfi was restricted to stromal cells, which also depicted a PDGFRa expression. Our results revealed a high rate of RTK co-expression in esophageal adenocarcinoma and squamous cell cancer and may encourage application of multi-target RTK inhibitors within a multimodal concept as a promising novel approach for innovative treatment strategies.