Inhibitory Effects Of DNT Cells On Growth Of Pancreatic Cancer In Vitro/vivo And Its Mechanism

Pancreatic carcinoma (PC) is one of the most malignant digestive tract malignanttumors. Due to its special disease position which is deep in belly and incidence occult,it’s always late to diagnose. And its biological characteristics is easy to infiltrate localareas and metastasize distantly, it becomes more and more dangerous. In recent years,Pancreatic carcinoma has elevated its morbidity and mortality year by year. So how todiagnose and treat PC better is an emergent problem. The percent of CD4-CD8-T cell(double negative T cell, DNT) in peripheral blood lymphocytes is1%－5%, it canexpress Fas/FasL、TNF/TNFR，CD3+、CD4-、CD8-、MHCⅠ. DNT cells haveimportant roles in immune regulation, immune suppression, autoimmune andanti-tumor activity.This study is based on the focus on the Immunology which is participated in tumor’sdiagnosis and treatment. We isolate and amplify the DNT cells from peripheral bloodand define it as DNT cells in flow cytometry. We use MTT to prove DNT cells caninhibit the Panc-1cells in vitro, and Nude mice experiment to prove DNT cells caninhibit the Panc-1cells in vivo. We also use PCR to find out the mechanism of theinhibitory.ObjectiveTo find out the effects and mechanism of CD4-CD8-double negative T（DNT） cellwhich depresses the pancreatic cancer in vitro and vivo.MethodsThe inhibitory effects of DNT cells on the growth of Panc-1were studied in vitro byMTT method．To divide18BALB/c mice into3groups randomly. Human pancreaticcancer xenografts were established in2groups randomly. The last group was injectedthe cell suspension which comprises DNT and Panc-1cells(Panc-1: DNT=1:5).Whenthe diameter of tumor was about5mm, the first2group mice were further more divided into2groups randomly. One is control, treated with distilled water. The otherwas treated with celebrex(4mg/d). The size of the tumors was calculated every2weeks and tumor growth curve was depicted. At the end of the treatments, the micewere killed and the tumors were harvested. The tumor inhibition rate was calculated.To detect the change of Fas/FasL pathway on Panc-1after the co culture of DNT andPanc-1cells.Results(1) MTT study showed that DNT cells can produce a dose-dependent inhibition ofPanc-1proliferation in vitro.(2) The growth of transplanted pancreatic cancer was down-regulated by hetreatment of DNT cells．(3) PCR shows Fas up-regulates its expression while FasL down-regulates itsexpression.ConclusionsDNT cells can inhibit the growth of pancreatic cancer in vitro and vivo. DNT cellscan inhibit the growth of pancreatic cancer in Fas/FasL pathway.