Abstract 906: Gene expression analysis of circulating endothelial cells in cancer patients

Abstract

Abstract It has been reported that the number of circulating endothelial cells (CECs) is higher in cancer patients compared to healthy controls. CECs may be acting as possible markers of vascular turnover or damage. Elevated level of CEC number has been reported to be correlated with tumor progression or response to anti-angiogenic therapy. Tumor endothelial cells (TECs) could be shed into circulation and being included in CECs. We have reported that primary cultured mouse TECs express reported TEC-specific markers, such as CD13, TEMs, Dickkopf-3 (Dkk-3) and others. In this study, we analyzed the expression of these TEC markers in CECs in lung cancer patients. Before and/or after dissecting tumor tissue, blood was collected and RNAs from peripheral blood mononuclear cells (PBMCs) were extracted from the patients. And mRNA expression of EC markers and several TEC markers, including both reported and novel candidate, were analyzed. We detected CD31 and CD105 expression in both lung cancer patients’ and healthy controls’ PBMCs. The expression levels of TEC markers and several novel TEC candidate genes were analyzed and compared with healthy controls. Expression levels of several TEC markers including novel TEC marker X and Y, which were expressed in human cultured TECs, were higher in cancer patients than in healthy controls. However, it was difficult for us to detect TEC marker gene expressions in PBMC from cancer patients’ blood since TECs are very small population in PBMC (0.2%). In order to obtain more concentrated TECs from lung cancer patients’ blood, we used blood from lung tumor specimen when lung cancer specimens were dissected under video-assisted thoracic surgery. This specimen (lung tumor specimen blood) contains pulmonary vein blood and it was thought to contain more TECs shed from lung tumor. So we isolated mononuclear cells form this specimen and analyzed TEC marker gene expressions. We sorted mononuclear cells by flow cytometry using anti-CD31 and anti-CD45. TECs are supposed to be included in CD31(+) CD45(−) (Q4) fraction. Novel TEC candidate marker gene X and Y expressions were detected, in crude mononuclear cells from the lung tumor specimen blood at high levels, but very low levels in CD31(−))CD45(+) (Q1) fraction or CD31(+)CD45(+) (Q2) fraction, leading a possibility that the gene X and Y were highly expressed in Q4 fraction. These results suggest that the lung tumor specimen blood can be one of useful materials to discover novel CTEC marker genes in lung cancer patients, and that these markers could be surrogate markers or predicted markers for anti-angiogenic therapy in lung cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 906. doi:10.1158/1538-7445.AM2011-906