Study Of The Function Of Syk And VEGF-C In Lymphatic Metastasis Of Non-small Cell Lung Cancer

[Objective and Background]:Lung cancer is one of the malignant tumor whose fatality rate is rather high all over China and even the world,still has a gradually increasing trend in recent years. And non-small cell lung cancer accounts for about80%of all,having a difficult early diagnosis. About70%of the patients with non-small cell cancer have lost the opportunity of surgery when confirmed.Many studies have demonstrated that its pathogenesis,involving multiple genes and other factors.is very complex.As a non-receptor tyrosine kinase. many researches have assured,Syk is found not only in all hematopoietic cells,but also in nasal fibroblasts. vessel endothelial cells.mammary epithelial cells,airway epithelial cells,neuron-like cells, liver cells, melanocytes and pancreatic epithelial cells which are non-hematopoictic cells. At present,several cancer researches,relating to breast cancer.gastric cancer, pancreatic cancer,have been assured the potential inhibiting effect of Syk.It has been proved that the expression of Syk gradually reduces in normal breast tissue,benign lesions,low grade malignant breast tumor,invasive breast cancer,and lacks in invasive breast cancer;No expression of Syk gene has been detected in gastric carcinoma with the method of RT-PCR;Chen Mingxia,who has used RT-PCR method to study pancreatic cancer,got a similar result.Vascular endothelial growth factor-C (VEGF-C). which is found having the effect of lymphangiogenesis,is also named lymphangiogenesis factor.It has its specific receptor VEGFR-3,and they can promote lymphangiogenesis and metastasis of malignant tumors.Despite of widely carrying out of research of lung cancer methylation,reports in expression of Syk and regulation induced by methylation are in deficiency. The method of RT-PCR was used to detect Syk and VEGF-C’s expression in non-small cell lung cancer tissue and normal lung tissue respectively.Meanwhile,we attempted to evaluate the relationship between Syk’s expression and clinicopathological factors,and also evaluate the correlationship between Syk and VEGF-C.This study was to explore the role of the Spleen tyrosine kinase(Syk) and Vascular Endothelial Growth Factor C(VEGF-C)in lymphatic metastasis of non-small cell lung cancer (A549cell).[Materials and Methods]:1.To evaluate the expression of Syk and VEGF-C we used81surgically resected materials of non-small cell lung cancer,paracancerous lung and normal lung,while RT-PCR evaluation were performed.And we used statistical analysis to evaluate the relationship between Syk’s expression and clinicopathological factors,and also evaluate the correlationship between Syk and VEGF-C.2.(1).To construct the eukaryotic expression vector,named pcDNA3.1-VEGF-C which carries people’s gene fragment VEGF-C and pLNCX-syk which carries Syk.(2).To transfer these genes into A549cells with the liposomes.(3).After screening the cells growing stablely, to test the level of VEGF-C with RT-PCR and detect Syk with RT-PCR.(4).To investigate the cell invasion assay with transwell chamber in vitro.[Results]:The positive expression rate of Syk in non-small cell lung cancer, paracancerous lung and normal lung was4.9%,92.6%,100%,there were obviously statistical differences between the expression levels of Syk of normal,paracancerous and cancerous tissues (P<0.05).There were no distinctly significant differences between the expression levels of Syk of normal,paracancerous tissues (P>0.05). Evaluations based on clinicopathological factors apart from histopathological differentiation,showed no statistically significant differences of Syk expression (P>0.05).The positive expression percentage of VEGF-C in non-small cell lung cancer,paracancerous lung and normal lung was88.9%,12.3%,2.5%eachly,there were statistically significant differences among VEGF-C’s expression levels of normal, paracancerous and cancerous tissues (P<0.05).There were no statistically significant differences between VEGF-C’s expression levels of normal,paracancerous tissues (P>0.05).The expression of Syk and VEGF-C has a negative correlationship(r=-1.000, P=0.000).The gene fragments pcDNA3.1-VEGF-C and pLNCX-syk were constructed successfully with restriction enzyme digestion and tsted by gel electrophoresis.Higher expression of VEGF-C was revealed in VEGFC-construct-transfected A549cell than that in controls through RT-PCR (P<0.05).RT-PCR also revealed that Syk expression was higher in syk-construct-transfected cells than in controls(P<0.05). The cell invading experiments showed that there was more invaded cells in both transfected terms than in controls (P＜0.05).【Conclusion】:the expression of Syk in non-small cell cancer significantly reduced, while the expression of VEGF-C significantly increased,they have a negative correlationship and may both have some certain effect on the occurance and development of NSCLC.Whether Syk has any influence on VEGF-C/VEGFR-3pathway or it could be used for diagnosis and treatment of lung cancer still needs more further study.There is no expression of Syk in non-small cell lung cancer.and the upregulation of Syk and VEGF-C expression has some potential links in lymphatic metastasis of non-small cell lung cancer.