Decreased expression of the chemokine CCL21 in human colorectal adenocarcinomas

Recent studies have revealed participation of chemokines in cancer by regulating leukocyte movement to modify local immunoresponse. The chemokine CCL21 has been identified to play a pivotal role in homing and localization of immune cells to lymphoid tissue and into organ of non-lymphoid origin. In the cancer biology CCL21 seems to have multifaceted roles. CCL21 attracts CCR7 bearing cells especially T and dendritic cells but also various cancer cells. Besides the antitumour role as leukocyte recruiting, CCL21 has been shown to facilitate dendritic cell functions and to exert an angiostatic effect. To gain insight into the possible influence of CCL21 on colorectal cancer (CRC) we determined whether the CCL21 is altered in CRC tissue. Collectively, by using ELISA we noted a significant lower CCL21 level in cancer tissue compared with paired normal tissue. Patients with a tumour localized in the rectum revealed significantly lower level of CCL21 than patients with a tumour localized in the colon both compared with paired normal tissue. We used immunohistochemistry and found heterogeneous immunoreactivity predominantly within areas of stromal cells mainly in macrophages. We also used a TaqMan system to investigate two single-nucleotide polymorphisms rs 11574915 and rs 2812377 with supposed effect on CRC. No significant difference was observed between CRC and control subjects regarding genotype and allelic distributions or associations to clinical characteristics or CCL21 tissue levels. Our study implied that lower level of CCL21 in CRC tissue supports the idea that cancer is related to immunodeficiency probably depending on regulatory factors produced by tumour cells and that the different levels of CCL21 in rectum and colon may reflect divergent mechanisms in colorectal carcinogenesis. Further studies are needed to clarify whether the CCL21 level has an impact on CRC progression and survival rate.