Angiogenic switch occurs during the precancerous stage of human esophageal squamous cell carcinoma

We previously reported that vascular endothelial growth factor (VEGF) expression correlates with vessel density in human esophageal squamous cell carcinomas. However, tumor angiogenesis is not controlled simply by the presence of VEGF, and is likely regulated by several angiogenic factors produced by tumor and host cells. The goal of the present study was to determine the angiogenic profile of precancerous and cancerous lesions of the esophagus. Expression of mRNAs for VEGF, platelet derived endothelial cell growth factor (PD-ECGF), basic fibroblast growth factor (bFGF), and interleukin (IL)-8 was examined in six esophageal carcinoma cell lines and fresh biopsy specimens from 16 patients with invasive esophageal carcinoma by RT-PCR. Immunohistochemical analyses with antibodies against VEGF, PD-ECGF, bFGF, and IL-8 were performed on archival specimens of 60 normal esophageal mucosa, 11 dysplasias and 49 carcinomas of the esophagus. Microvessels were stained with anti-CD34 antibody and quantified by counting the number of vessels in a x200 field in the most vascularized areas of the tumor. Esophageal carcinoma cell lines and tumor tissues expressed mRNAs for one or more these angiogenic factors at various levels. An initial increase in vessel density and enhanced expression of PD-ECGF and VEGF were observed in dysplastic epithelium. Vessel density was significantly higher in more advanced lesions. bFGF and IL-8 were not expressed in dysplasias and mucosal carcinomas, but expression was increased in late stage squamous cell carcinoma. These findings suggest that the angiogenic switch is a very early event in the development of invasive carcinoma. Several different angiogenic factors produced by tumor cells and host cells may regulate angiogenesis during different steps of esophageal carcinogenesis.