Downregulation Of DAB2IP Promotes Radioresistance In Esophageal Squamous Cell Carcinoma

Background DAB2IP(DOC-2 / DAB2 interactive protein)gene is a newly discovered tumor suppressor gene,which is closely related to many tumors.Recently,many discoveries have found that DAB2 IP expression is down-regulated or silenced during the development and progression of many tumors,such as prostate cancer,breast cancer,colorectal cancer,lung cancer,and so on.DAB2 IP has been wellknown in these tumors,but its expression and role in esophageal cancer are unknown.Objective To investigate the expression of DAB2 IP in esophageal cancer and whether it plays a role in radiosensitivity of esophageal cancer.Methods The expression of DAB2 IP in normal esophagus and esophageal cancer was detected by Western Blot.The overexpressing cell line Kyse150-DAB2 IP and the Kyse150-vector were constructed,and the EC109 knockout cell line control group EC109-shluc and the knockout group EC109-sh DAB2 IP were constructed.The experiments of apoptosis about EC109-shluc and EC109-sh DAB2 IP after radiation were detected by flow cytometry.EC109-shluc and EC109-sh DAB2 IP cells were irradiated,and then immunofluorescence confocal experiments were performed to detect the expression of 53BP1 and γ-H2 AX,and compare the results caused by radiotherapy to estimate whether DAB2 IP have a effect on the DNA damage.Kyse150 nude mice transplanted tumor model was established.The nude mice were treated with radiation and non-radiation treatment after tumor formation.The tumor size was measured and statistically analyzed.Immunohistochemistry and immunofluorescence confocal experiments were performed on the excised tumors.Finally,we demonstrated that DAB2 IP regulates ESCC cell radiosensitivity through enhancing ionizing radiation(IR)-induced activation of the ASK1-JNK signaling pathway.Results WB detection revealed that DAB2 IP protein expression was higher in normal cells,while ESCC cell lines all expressed relatively lower DAB2 IP.Annexin-V / PI double staining showed that knockdown of DAB2 IP resulted in reduced apoptosis.Cell immunofluorescence confocal analysis showed that EC109-sh DAB2 IP repaired more DNA damage than EC109-shluc.In the tumor formation experiments of nude mice,compared with Kyse150-vector received 6Gy irradiation,Kyse150-DAB2 IP tumors were significantly inhibited after receiving 6Gy IR irradiation.The expression of DAB2 IP in xenografts was detected by immunohistochemistry.The expression of 53BP1 and γ-H2 AX in transplanted tumors was determined by immunofluorescence staining.Comparing the DNA damage of the two groups,it was found that Kyse150-DAB2 IP tumor DNA repair was less.Finally,WB may be used to explore the mechanism of DAB2 IP enhancing radiosensitivity through the ASK1-JNK pathway.Conclusion The protein expression level of DAB2 IP and esophageal cancer was low.DAB2 IP affects apoptosis after irradiation and is related to DNA damage.Low expression of DAB2 IP can cause radioresistance in esophageal cancer.Therefore,DAB2 IP may become a significant biomarker and an effective breakthrough in radiotherapy for esophageal cancer.