Expression in cancer cells of tumors like lung, hepatocellular, and urinary bladder cancer as well as melanoma we suggested that elevated Foxp3 expression levels were not necessarily associated to Treg alone but also to cancer cells [10,14,15]. Expression of Foxp3 by cancer cells would enable them to downregulate effector T cell responses directed against the tumor. This would give clinical evidence for an effective mechanism of a direct tumor-derivedevasion from immunological destruction in CRC. By discriminating Foxp3 expression of cancer cells 
from infiltrating Treg and correlating with overall survival over a long-term follow-up we provide new insights in its prognostic significance. In accordance with previous studies in various malignant diseases we found significantly higher numbers of infiltrating Treg (CD4+CD25+Foxp3+) in all CRC samples compared with normal colon tissues [4?,17?0]. I-BRD9 site However, the association of Foxp3 expression in Treg and its impact on overall survival remains controversial. Ambiguous data suggest that tumor infiltration by Foxp3+ Treg is not always associated with a poor prognosis, but, on the contrary, can be associated with an improved prognosis in some cancer types like in CRC [8,9,21,22]. Moreover, no significant relation was observed GW 0742 site between the absolute number of Foxp3+ Treg and prognosis in CRC [23,24]. Improved survival and the potentially protective role of Treg might be explained by their capacity of reducing the development of an aggressive and cytotoxic, potentially proliferogenic cytokine milieu, which is the basis for an inflammation-driven progress of malignant diseases [25,26]. Experimental studies in mice showed that CD4+CD25+Treg do not only play a central role in the maintenance of immunological tolerance but that Treg are also potent inhibitors of antitumor immune responses [27,28]. Previous studies have examined the suppressive capacities of CD8+CD25+Foxp3+ T cells in colorectal cancer tissues [29]. In CRC specimens the absolute number of CD8+CD25+Foxp3+ T cells were low (,5 ). In addition, theseFoxp3 Expression and CRC Disease Progressionthe tumor a powerful tool to circumvent immunological destruction. Interestingly, an inverse correlation between the number of Foxp3+ Treg and the level of Foxp3+ cancer cells was observed in our patients with CRC suggesting an anti-proliferative effect of TGF-b on Treg. In conclusion, despite the fact that the sample size in this cohort is small to draw 1662274 definitive conclusions, our study shows for this first time that high Foxp3 expression in cancer cells is associated with a dismal prognosis in CRC. Multivariate Cox regression analysis demonstrated lymph node metastasis (N category) and Foxp3 expression in colon cancer cells as significant prognostic parameters of survival in human CRC.Materials and Methods Ethics statementEthical approval for this research was obtained from the Human Research Ethics Committee of the University of Wuerzburg. All patients providing tumor tissue as well as normal colon tissue samples signed a consent form prior to surgical removal of the intestinal cancer to allow for this research to be undertaken.Patients and controlsSixty-five patients with histologically confirmed CRC cancer undergoing curative surgical resection in our department between 01/2001 and 06/2004 were included in the study. The histological stage of the tumor was determined according to the Union Internationale Contre le Cancer (UICC)-TNM staging system [3.Expression in cancer cells of tumors like lung, hepatocellular, and urinary bladder cancer as well as melanoma we suggested that elevated Foxp3 expression levels were not necessarily associated to Treg alone but also to cancer cells [10,14,15]. Expression of Foxp3 by cancer cells would enable them 
to downregulate effector T cell responses directed against the tumor. This would give clinical evidence for an effective mechanism of a direct tumor-derivedevasion from immunological destruction in CRC. By discriminating Foxp3 expression of cancer cells from infiltrating Treg and correlating with overall survival over a long-term follow-up we provide new insights in its prognostic significance. In accordance with previous studies in various malignant diseases we found significantly higher numbers of infiltrating Treg (CD4+CD25+Foxp3+) in all CRC samples compared with normal colon tissues [4?,17?0]. However, the association of Foxp3 expression in Treg and its impact on overall survival remains controversial. Ambiguous data suggest that tumor infiltration by Foxp3+ Treg is not always associated with a poor prognosis, but, on the contrary, can be associated with an improved prognosis in some cancer types like in CRC [8,9,21,22]. Moreover, no significant relation was observed between the absolute number of Foxp3+ Treg and prognosis in CRC [23,24]. Improved survival and the potentially protective role of Treg might be explained by their capacity of reducing the development of an aggressive and cytotoxic, potentially proliferogenic cytokine milieu, which is the basis for an inflammation-driven progress of malignant diseases [25,26]. Experimental studies in mice showed that CD4+CD25+Treg do not only play a central role in the maintenance of immunological tolerance but that Treg are also potent inhibitors of antitumor immune responses [27,28]. Previous studies have examined the suppressive capacities of CD8+CD25+Foxp3+ T cells in colorectal cancer tissues [29]. In CRC specimens the absolute number of CD8+CD25+Foxp3+ T cells were low (,5 ). In addition, theseFoxp3 Expression and CRC Disease Progressionthe tumor a powerful tool to circumvent immunological destruction. Interestingly, an inverse correlation between the number of Foxp3+ Treg and the level of Foxp3+ cancer cells was observed in our patients with CRC suggesting an anti-proliferative effect of TGF-b on Treg. In conclusion, despite the fact that the sample size in this cohort is small to draw 1662274 definitive conclusions, our study shows for this first time that high Foxp3 expression in cancer cells is associated with a dismal prognosis in CRC. Multivariate Cox regression analysis demonstrated lymph node metastasis (N category) and Foxp3 expression in colon cancer cells as significant prognostic parameters of survival in human CRC.Materials and Methods Ethics statementEthical approval for this research was obtained from the Human Research Ethics Committee of the University of Wuerzburg. All patients providing tumor tissue as well as normal colon tissue samples signed a consent form prior to surgical removal of the intestinal cancer to allow for this research to be undertaken.Patients and controlsSixty-five patients with histologically confirmed CRC cancer undergoing curative surgical resection in our department between 01/2001 and 06/2004 were included in the study. The histological stage of the tumor was determined according to the Union Internationale Contre le Cancer (UICC)-TNM staging system [3.