Expression And Clinical Significance Of Mesothelin In Pancreatic Cancer And Peripheral Lymph Nodes

IntroductionThe early diagnosis for pancreatic cancer has become a topic of significance at present since pancreatic cancer is regarded as the worst prognosis malignant tumor of alimentary system.Mesothelin,as the new-found tumor markers,can be expressed in the cancer of bile duct,gastric cancer,pancreatic cancer and so forth.Mesothelin is synthesized as a precursor of molecular mass 69kDa.one part is a 40 kDa glycosylphosphatidylinositol-linked glycoprotein,the other is the N-terminal secreted form of 31kDa,that is megakaryocyte-potentiating factor,can discharge into blood or further degrade.The research aims to detect the expression of mesothelin in pancreatic cancer and peripheral lymph nodes by the immunohistochemical method;analyze the correlation between expression of mesothelin in pancreatic cancer and some clinical pathology factors,such as age of patients,size of tumors,pathology stages of operation and histology classification by means of statistic analysis.MethodThe research bases on the tissues preserved in the department of pathology of Shengjing Hospital of China Medical University.There are 60 samples of patients with postoperative pancreatic cancer and 84 ones of lymph nodes from 2003 to 2008.There are 36 male samples and 24 female samples.Among 60 samples,the patients younger than 60 is 34 samples and older than 60 is 26 samples respectively.The age on average is 58.5 years old.Size of rumors:the size smaller than 4cm is 38 samples,that larger than 4cm is 22 samples.According to staging standard of pancreatic cancer from UICC(2002),pathology grade of operation is:Ⅰ,41 samples,Ⅱ,Ⅲ,Ⅳ,19 samples.Degree of differentiation:there are 20 well differentiated samples and 40 moderately or poorly differentiated samples.36 lymph nodes are certified metastatic by HE stain,while 48 metastases zero lymph nodes.The research detects the relation between mesothelin and clinical pathology factors of pancreatic cancer.First paraffin section is dewaxed as routines,incubated for 15 minutes in 3%hydrogen peroxide with room temperature,nonspecific antigens were blocked with normal calf serum.Primary antibody(working dilution:1:20) can be added to and transferred to 4℃freezer overnight,Staining was achieved by using a biotinylated anti-mouse secondary antibody and antibody binding was amplified using biotin.Then,after the section has been incubated with room temperature for 30 minutes one drop of strepto-albumin fluid with armoracia rusticana enzyme label can be added to.DAB chromogenic agent can be dropped into after 30-minute incubation with room temperature.Other procedures are as the same as the above-mentioned in control group except for PBS's substitutes for primary antibody.Differences were considered to be statistically significant when the probability value was less than 0.05.Result1.The correlation between mesothelin and clinical pathology factors of pancreatic cancer:positive expression of mesothelin is 43 samples(71.7%),negative expression of mesothelin is 17 samples(28.3%).Expression of mesothelin in moderately or poorly differentiated pancreatic cancer tissues(87.5%) is evidently higher than that in well differentiated samples(40%)(P＜0.05).However there is no evident correlation between expression of mesothelin and age of patients,size of tumors, pathology stages of operation and metastatic lymph nodes or metastases zero lymph nodes(P＞0.05).2.Expression of mesothelin in pancreatic cancer tissues:there are 22 lymph nodes with positive expression of mesothelin in 36 metastatic lymph nodes(certified by HE stain),The positive expression rate is 61.1%;there are 17 lymph nodes with positive expression of mesothelin in 48 metastases zero lymph nodes.The positive expression rate is 35.4%.There is no statistic difference between HE stain and mesothelin immunohistostaining for identifying micrometastasis(P＞0.05).Conclusion1.Expression of mesothelin in moderately or poorly differentiated pancreatic cancer tissues is evidently higher than that in well differentiated samples which hints the possible correlation between moderately or poorly differentiated pancreatic cancer and early lymph nodes metastasis. 2.There is no evident difference between expression of mesothelin and age of patients,size of tumors,pathology stages of operation and metastatic lymph nodes or metastases zero lymph nodes.3.Positive expression of mesothelin will contribute to the diagnosis of micrometastasis of lymph nodes but the clinical functions depend on further researches.