The role of the epithelial cell adhesion molecule EpCAM in cancer progression remains largely unclear. High expression of EpCAM in primary tumors is often associated with more aggressive phenotypes and EpCAM is the prime epithelial antigen in use to isolate circulating tumor cells (CTCs) and characterize disseminated tumor cells (DTCs). However, reduced expression of EpCAM was associated with epithelial-to-mesenchymal transition (EMT) and reports on a lack of EpCAM on CTCs emerged. These contradictory observations might reflect a context-dependent adaption of EpCAM expression during metastatic progression. To test this, EpCAM expression was monitored in esophageal cancer at different sites of early systemic disease. Although most of the primary esophageal tumors expressed high levels of EpCAM, the majority of DTCs in bone marrow lacked EpCAM. In vitro, downregulation of EpCAM expression at the plasma membrane was observed in migrating and invading cells, and was associated with a partial loss of the epithelial phenotype and with significantly decreased proliferation. Accordingly, induction of EMT through the action of TGFb resulted in substantial loss of EpCAM cell surface expression on esophageal cancer cells. Knock-down or natural loss of EpCAM recapitulated these effects as it reduced proliferation while enhancing migration and invasion of cancer cells. Importantly, expression of EpCAM on DTCs was significantly associated with the occurrence of lymph node metastases and with significantly decreased overall survival of esophageal cancer patients. We validated this observation by showing that high expression of EpCAM promoted tumor outgrowth after xenotransplantation of esophageal carcinoma cells. The present data disclose a dynamic expression of EpCAM throughout tumor progression, where EpCAM high phenotypes correlate with proliferative stages, whereas EpCAM low/negative phenotypes associated with migration, invasion and dissemination. Thus, differing expression levels of EpCAM must be taken into consideration for therapeutic approaches and during clinical retrieval of disseminated tumor cells.

The oxygen-regulated transcription factor subunit hypoxia inducible factor-1alpha (HIF-1alpha) is involved in angiogenesis, energy metabolism, cell survival, and inflammation. We examined the protein expression of HIF-1alpha within the progression of Barrett's sequence as well as the type and degree of the environmental inflammatory reaction. Squamous epithelium (SE), metaplastic, low- and high-grade dysplastic lesions, and tumor tissue of 57 resection specimens from patients with Barrett's adenocarcinoma were immunohistochemically analyzed. Active and chronic inflammatory reactions were classified according to the Updated Sydney System. HIF-1alpha protein expression increased significantly from SE to Barrett's metaplasia (BM) (P < 0.0001). From metaplasia through low- and high-grade dysplasia to cancer, no further increase could be detected. Active and chronic inflammation were also significantly different between SE and BM (P < 0.0001) but not during further progression in the sequence. HIF-1alpha protein expression did not correlate with histopathologic parameters or survival. HIF-1alpha protein expression pattern resembles the active and chronic environmental inflammatory reaction. All were significantly increased in metaplasia compared to SE without further change in tumor development. HIF-1alpha protein expression appears to be associated with inflammatory processes in the development of BM.

Recent studies have shown an association between the GNAS1 T393C polymorphism and clinical outcome for various solid tumors. In this study, we genotyped 51 patients from an observational trial on cisplatin/5-FU-based neoadjuvant radiochemotherapy of locally advanced esophageal cancer (cT2-4, Nx, M0) and genotyping was correlated with histomorphological tumor regression. The C-allele frequency in esophageal cancer patients was 0.49. Pearson's w 2 -test showed a significant (Po0.05) association between tumor regression grades and T393C genotypes. Overall, 63% of the patients in the T-allele group (TT þ CT) were minor responders with more than 10% residual vital tumor cells in resection specimens, whereas T(À) genotypes (CC) showed a major histopathological response with less than 10% residual vital tumor cells in 80%. The results support the role of the T393C polymorphism as a predictive molecular marker for tumor response to cisplatin/5-FU-based radiochemotherapy in esophageal cancer.

Patients with ESCC (squamous cell carcinoma of the esophagus) are most commonly diagnosed with locally advanced tumor stages. Early metastatic disease and late diagnosis are common reasons responsible for this tumor's poor clinical outcome. The prognosis of esophageal cancer is very poor because patients usually do not have symptoms in early disease stages. Squamous cell carcinoma of the esophagus frequently complicates patients with multiple co-morbidities and these patients often require interdisciplinary diagnosis and treatment procedures. At present time, neoadjuvant radiation therapy and chemotherapy followed by surgery are regarded as the international standard of care. Meta-analyses have confirmed that this approach provides the patient with better local tumor control and an increased overall survival rate. It is recommended that patients with positive tumor response to neoadjuvant therapy and who are poor surgical candidates should consider definitive radiochemotherapy without surgery as a treatment option. In future, EGFR antibodies may also be administered to patients during therapy to improve the current treatment effectiveness. Positron-emission tomography proves to be an early response-imaging tool used to evaluate the effect of the neoadjuvant therapy and could be used as a predictive factor for the survival rate in ESCC. The percentage proportions of residual tumor cells in the histopathological analyses represent a gold standard for evaluating the response rate to radiochemotherapy. In the future, early response evaluation and molecular biological tests could be important diagnostic tools in influencing the treatment decisions of ESCC patients.