The Molecular Mechanisms Research On The Homing Metastases Of Metastatic Colorectal Cells To Liver

[Objects] Colon cancer is characterized by a striking tendency to metastasize to liver, which is called directionally metastatic pattern, and new evidence suggests that some kind of tumor metastasis shares many similarities with leukocyte trafficking. Whether the distribution pattern of circulating colon cancer cells have the similar regulation to leukocyte homing to inflammation, and what is the key factor inducing the directional metastasis of colon cancer cells to liver are the main questions discussed in this research. To address these questions and to explore the internal mechanism, we evaluated the effects of chemokine receptor CXCR1 in human colon cancer liver metastasis; we analyze the expression of CXCR1 in human colon cancer with different metastatic potentials and the target organ. In addition, we are also exploring the relation between the expression of CXCR1 in colon cancer cell lines and E-cadherin, which mediates the stable adhesion of cancer cells.[Materials and mathords] The following human colonrectal cancer cell lines which were used in this research were obtained from Cells storeroom of Tianjin Cancer Hospital affiliated to Tianjin Medical Universtity: The expression of chemokine receptor CXCR1 is detected in the sample of the primary colon cancer and liver metastatic focus, high differential colon cancer and human colon cancer cell lines with different metastatic potentials, as well as in the sample of the normal colon and liver tissues. CXCL8-mediated expression of CXCR1 andthe changing mRNA levels of E-cadherin and F-actin in Lovo and Colon205 are determined respectively using Flow Cytometry, Real-time quantitative polymerase chain reaction (PCR). The change of cytoskeleton and morphology induced by the interactions of CXCRl and CXCL8 was observed under electron microscopy, confocal microscopy and with immunocytochemistry. The characteristics of chemotaxis and infiltration potency of Lovo cell were shown by Boyden chamber. The contribution of CXCR1/CXCL8 interactions on metastasis in vivo is evaluated by using experimental and spontaneous liver metastasis models of colon cancer. Actin polymerization was tested as described. At the indicated time points, cells were fixed, permeabilized and stained in a solution containing paraformaldehyde, lysophosphatidylcholine and fluorescein isothiocyanate-labelled phalloidin. Fixed cells were subjected to flow cytometry or analysed by confocal microscopy. Migration and invasion of the cell line was assayed in the modified Boyden chamber. The in vivo metastasis studies were performed in mice and the model of metastatic colorectal cancer to liver were established at the mice.[ Results ]The expression of CXCRl has heterogeneity on the different kind of colon cancer cells and colon cancer tissues. The liver metastatic colon cancer cell line (Lovo) has the capability of increasing the expression of CXCRl under the stimulation of CXCL8 and the liver metastatic focus has a high expression level of CXCRl. The invasive cell numbers of Lovo cell line was significantly different in the presence of CXCL8 or not and the former was higher than the later. The result shows that the interaction between the ligand and receptor increases the invasive and migration capacity of colorectal cell. The expression of E-cadherin and CXCRl was different in the surface of the tumor cell line with the role of the responding ligand. It is inferred that signaling through the interaction of ligand and receptor mediates actin polymerization and pseudopodia formation, andsubsequently induces chemotactic and invasive responses according to the phenomenon observed in this research, in vivo, neutralizing the interaction significanctly impairs metastasis of the tumor cells to the target organ.[ Conclusions ] It has been proposed that molecules regulating the metastasic dissemination of tumor cells to specific anatomical sites need to fufil the following criteria. First, they have to be constitutively expressed at principle sites of metastasis. Second, adhesion of target cells to the...