Metastatic Esophageal Carcinoma Cells Exhibit Reduced Adhesion Strength and Enhanced Thermogenesis

Despite continuous improvements in multimodal therapeutic strategies, esophageal carcinoma maintains a high mortality rate. Metastases are a major life-limiting component; however, very little is known about why some tumors have high metastatic potential and others not. In this study, we investigated thermogenic activity and adhesion strength of primary tumor cells and corresponding metastatic cell lines derived from two patients with metastatic adenocarcinoma of the esophagus. We hypothesized that the increased metastatic potential of the metastatic cell lines correlates with higher thermogenic activity and decreased adhesion strength. Our data show that patient-derived metastatic esophageal tumor cells have a higher thermogenic profile as well as a decreased adhesion strength compared to their corresponding primary tumor cells. Using two paired esophageal carcinoma cell lines of primary tumor and lymph nodes makes the data unique. Both higher specific thermogenesis profile and decreased adhesion strength are associated with a higher metastatic potential. They are in congruence with the clinical patient presentation. Understanding these functional, biophysical properties of patient derived esophageal carcinoma cell lines will enable us to gain further insight into the mechanisms of metastatic potential of primary tumors and metastases. Microcalorimetric evaluation will furthermore allow for rapid assessment of new treatment options for primary tumor and metastases aimed at decreasing the metastatic potential

CAIX furthers tumour progression in the hypoxic tumour microenvironment of esophageal carcinoma and is a possible therapeutic target

The hypoxic tumour microenvironment of solid tumours represents an important starting point for modulating progression and metastatic spread. Carbonic anhydrase IX (CAIX) is a known HIF-1α-dependent key player in maintaining cell pH conditions under hypoxia. We show that CAIX is strongly expressed in esophageal carcinoma tissues. We hypothesize that a moderate CAIX expression facilitates metastases and thereby worsens prognosis. Selective inhibition of CAIX by specific CAIX inhibitors and a CAIX knockdown effectively inhibit proliferation and migration in vitro. In the orthotopic esophageal carcinoma model, the humanized HER2 antibody trastuzumab down-regulates CAIX, possibly through CAIX’s linkage with HER2 in the hypoxic microenvironment. Our results show CAIX to be an essential part of the tumour microenvironment and a possible master regulator of tumour progression. This makes CAIX a highly effective and feasible therapeutic target for selective cancer treatment

Patient characteristics.

<p>Patient characteristics.</p

Metastatic sites.

<p>Metastatic sites.</p

PGK1 and CXCR4 expression, proliferation and inhibition of CXCR4 of neuroblastoma cell lines.

<p>Kelly (<b>A</b>) and SH-EP Tet-21/N (<b>B</b>) neuroblastoma cells were immunostained for PGK1 and CXCR4 expression (<b>Immunohistochemistry</b>). Both cell lines show a positivity for CXCR4 and react to treatment with 20 µg AMD3100 with an inhibition of proliferation (<b>MTT-assay</b>), although only SH-EP Tet-21/N cells reach a significant level of growth reduction. On examination of PGK1 protein expression levels (<b>Western blot</b>) after 48 h of CXCR4 receptor inhibition, treatment with 20 µg AMD3100 leads to a downregulation of PGK1 protein (45 kDa) in SH-EP Tet-21/N but not in Kelly cells. Tubulin (55 kDa) served as control.</p