| Background:Pancreatic cancer (PaCa) is one of the most common malignant tumors in the digestive system, which constitutes80%-90%of all the exocrine malignancies, with an still increasing trend of incidence worldwide. The curative surgery remains the only effective treatment to cure PaCa potentially. However, the early diagnosis for PaCa is difficult due to its anatomically profumdus location and asymptom in early stage. The advance of PaCa can occur early via lymphatic, nervous or vessel systems during onset. Without available sensitive measures of early detection, most cases are advanced at the time of first detection. About10%-15%patients have the opportunity for resections, only5%of which is curative. Even if the radical resection can be achieved, the undetectable micrometastasis could also jeopardize the effect of surgery. The recurrent rate of pancreatic cancer is high after surgery, with a postoperative five-year survival rate less than15%. The current understanding attributes the poor prognosis of PaCa to the high invasive and metastatic potential of its tumor cells. Increasing researches suggested that chemokines and their receptors functioned as key factors in the proliferation, invasion and migration of malignant tumor cells. Over50chemokines and20receptors have been indentified to date, in the progression of pancreatic cancer specifically, the role of the biological axis of CXCL12(stromal derived factor-1, SDF-1)/CXCR4and CCL25(thymus expressed chemokine, TECK)/CCR9are frequently investigated. The TECK/CCR9was screened out as differentially expressed gene across stages of PaCa by cDNA microarray of the specimen from subcutaneous and orthotopic transplantation tumor model in our prior research. The present study will look into the expression and function of different axis of chemokines and receptors in pancreatic cancer cell lines with diverse potential of progression.Purpose:1) To compare the expression of CXCL12/CXCR4and CCL25/CCR9in the tumor and adjacent tissue between the groups of better prognosis and poor prognosis, and also the correlation with the clincpathological features, of the PaCa patients who undergone curative resections.2) To investigate the expression and functions of CXCL12/CXCR4and CCL25/CCR9in PaCa cell lines with different potential of proliferation and invasion, the effect of chemokines will be further verified by blockade of corresponding receptors by specific antibodies.Methods:1) The patients undergone curative resections of primary PaCas were categorized according to postoperative survivals into two groups:better prognosis (survival no less than18months,30cases) and poor prognosis (survival less than6months,32cases). The expression of CXCL12/CXCR4and CCL25/CCR9in tumor and adjacent tissue was detected by immunohistochemistry (IHC), its correlation with the clincpathological features was also analyzed.2) The expression of CXCR4and CCR9in three PaCa cell lines with different potential of proliferation and invasion, Capan-1, Aspc-1and Mia PaCa-2, was evaluated by Rt-PCR, SQ-PCR and Western Blot.3) The effect of CXCL12and CCL25of promoting the proliferation and invasion on PaCa cell lines with different progression potential were verified by colony formation assay, MTT proliferation assay, Transwell invasion assay and cell cycle by flow cytometry analysis (FCM) associated with the blockade by corresponding antibodies of receptors.Results:1) The IHC of tumor and adjacent tissue indicated that CCL25/CCR9and CXCL12/CXCR4are mainly detected in the cytoplasm of PaCa cells. The density of positive staining of chemokine ligand didn’t demonstrate significant correlations with clincpathological features (p>0.05), whereas the strongly positive staining of chemokine receptors was associated with disease progression and poor prognosis (p<0.001, p<0.001), which was also synchronous with the staining of ligands in involved lymph nodes (r=0.31p=0.023, r=0.69p=0.002). This result supported that the interaction of ligands and receptors played certain role in the progression, especially lymph node metastasis, of PaCa. 2) The quantitative analysis of CCR9and CXCR4showed significant differences of expressions among the three PaCa cell lines with different potential of progression (CXCR4p=0.681,0.148,0.082, CCR9p=0.047,<0.001,<0.001), which suggested that PaCa cell lines with diverse differentiation have different ligand/receptors axis..3) The recombinant human TECK or SDF-1presented with the effect of promoting the proliferation and invasion of PaCa cells, the sensitivity of which was determined by the density of corresponding chemokine receptors. This effect can be neutralized by blockade of the chemokine receptors. This result also implied that the progression potential of PaCa cell lines was partly determined by the expression of receptors:cell line with high expression of receptors is more sensitive to the ligands and more invasive.Conclusion:The PaCa tumor cells express chemokine receptors, which varied from PaCa cell lines with different progression potentials. The chemokine ligands can promote the proliferation, by effecting the clone formation and cell cycles, and invasion by interacts with corresponding receptors in a concentration-dependent manner. The high expression of receptors, synchronous with the expression of ligands, in metastatic lymph nodes and adjacent tissue of PaCa patients with poor prognosis suggested that the progression of PaCa was related to the interaction of chemokine ligands and receptors. |
