The Expression,roles And Related Mechanism Of TIPE2 In Pancreatic Ductal Adenocarcinoma(PDAC)

Background:Pancreatic cancer is one of the most common malignant tumors of the digestive tract system.Among pancreatic cancer,pancreatic ductal adenocarcinoma(PDAC)is the most common type that accounting for 85%-90% of pancreatic cancer.At present,the treatment of PDAC is mainly based on surgery combined with radiotherapy and chemotherapy.However,most PDAC patients are found to be in an advanced stage and often have a poor prognosis due to the insidious onset.Therefore,discovering molecular markers of PDAC with high sensitivity and specificity are of great clinical significance to improve the prognosis for this devastating disease.Tumor necrosis factor-α-induced protein 8-like 2(TNFAIP8L2,TIPE2)was proven to play an important role in inflammation,immunity and tumor.However,the expression condition and roles of TIPE2 in PDAC remains largely unknown.This study combined with clinicopathological data for the first time to explore the relationship between TIPE2 and clinical characteristics of patients with PDAC.At the same time,we demonstrated the important malignant biological effects of TIPE2 in the occurrence and development of PDAC.Materials and methods:Tumor specimens and related normal tissues from 74 patients with PDAC were collected at the Affiliated Hospital of Qingdao University.The expression of TIPE2 in PDAC tissues was assessed by immunohistochemistry,q RT-PCR and western blot and related clinicopathological parameters including survival time were analyzed.To further elucidate the role of TIPE2 in PDAC,we investigated the malignant biological effects of TIPE2 on PDAC cells.First,we detected the TIPE2 expression in the human PDAC cell lines PANC-1 and SUIT-2 by q PCR and western blot.Then,PANC-1 and SUIT-2 cells were transfected with the PRK5-TIPE2 plasmid.In addition,CCK8 and colony formation assays were conducted to explore the effect of TIPE2 on cell proliferation;The effect of TIPE2 on the migration and invasion of PDAC cells was evaluated using scratch wound-healing assay and Transwell assay.Cell apoptosis was analyzed by flow cytometry.Meanwhile,the regulation effect of TIPE2 on survivin protein and caspase 3/7 activity in cells was studied to clarify the mechanism of TIPE2 in PDAC.Results:The results showed that TIPE2 staining in early tumor tissues was significantly increased compared to that in adjacent normal tissues.However,the expression of TIPE2 was markedly decreased in advanced stages with tumor progression compared to that in normal tissues.The expression of TIPE2 was closely related to tumor stage(P<0.001),lymph node metastasis(P<0.001)and tumor diameter(P=0.030).Subsequently,univariate and multivariate analysis in Cox proportional hazards model confirmed that tumor stage,tumor differentiation and TIPE2 expression were independent prognostic factors for PDAC patients;TIPE2 expression and PDAC patients’ survival showed a positive correlation(P=0.035).In addition to,it was discovered that TIPE2 m RNA expression and the corresponding protein levels was low PANC-1 and SUIT-2 cells.Then TIPE2 was overexpressed in the two cell lines using the PRK5-TIPE2 recombinant plasmid.Overexpression of TIPE2 inhibited the proliferation,suppressed cell invasion and migration and induced apoptosis of PDAC cells.Meanwhile,the results showed that TIPE2 induced the apoptosis and inhibited the proliferation of PDAC cells by inhibiting the expression of survivin and increasing the activities of caspase 3/7 subsequently.Conclusions:In the present study,we demonstrated for the first time that TIPE2 expression was upregulated in early tumor tissues but the levels of TIPE2 decreased in advanced stage PDAC tissues.In addition,TIPE2 serves as a biomarker for diagnosing PDAC and assessing the prognosis of patient.Mechanically,TIPE2 acts as a tumor suppressor by inhibiting survivin and regulating caspase 3/7.Therefore,TIPE2 serves as a bridge,allowing communicating among the three major areas of inflammation,immunity and tumors.Thus,revealing the functions of TIPE2 may lead to a breakthrough in future cancer prevention.