1.The Function And Mechanistic Study Of OTUD1 In The Chemoresistance Of Esophageal Cancer 2.The Function And Underlying Mechanism Of Long Non-coding RNA LOC101927476 In Ovarian Cancer Metastasis

Esophageal cancer is one of the most common gastrointestinal tumors with the sixth leading cause of the cancer death in the world.The development of chemotherapy resistance has become one of the most important reasons for the high mortality rate of esophageal cancer.In recent years,a large number of studies have shown that post-translational modifications of proteins play an essential role in the development of cancer,including ubiquitination and deubiquitination.After a three-enzyme cascade,E3 ubiquitin ligases promote or directly catalyze ubiquitin transfer to substrates,thereby regulating the stability or physiological activity of the substrate.Deubiquitinase can reverse the process of ubiquitination modification by hydrolyzing different types of ubiquitin chains on the substrate.By screening subcutaneous tumor formation experiments in nude mice and verifying drug-resistant cell lines,we found that the deubiquitinating enzyme OTUD1 function as a tumor suppressor and is closely related to chemotherapy resistance in esophageal squamous cell carcinoma.By analyzing 122 ESCC patients,we found that low OTUD1 expression was significantly correlated with poor prognosis.Ectopic expression of wild type OTUD1(OTUD1WT)significantly inhibited the cell viability and enhanced the sensitivity of KYSE30 and KYSE180 cells to cisplatin treatment,while ectopic expression of mutant type OTUD1(OTUD1C320A)didn’t have these effect.Down regulation of OTUD1 significantly inhibited the sensitivity of KYSE150 and YES2 cells to cisplatin treatment but had no effect on cell proliferation.Further studies revealed that OTUD1 affects cell viability by promoting the apoptosis of ESCC cell lines,which is independent on the activation of the caspase cascade pathway.In vivo tumor formation assay showed that upregulation of OTUD1WT inhibited tumor growth.Meanwhile,the tumor volume and weight of OTUD1WT transgenic group were significantly lower than that in OTUD1C320A transgenic group after cisplatin treatment.In order to clarify the mechanism of OTUD1,Apoptosis inducing factor(AIF)was identified to interacted with OTUD1 by mass spectrometry,which was confirmed by Co-Immunoprecipitation(co-IP).Further study showed that OTUD1WT promotes the transport of AIF from mitochondria to the nucleus,while the OTUD1C320A didn’t have this effect.Therefore,we speculated that OTUD1 affected the chemosensitivity of esophageal squamous cell carcinoma by altering nuclear localization of AIF.Taken together,we identified deubiquitinating enzyme OTUD1 function as a tumor suppressor in ESCC.Mechanistically,OTUD1 promotes the nucleus translocation of AIF and enhanced the sensitivity of ESCC to cisplatin treatment,thereby promoting apoptosis of ESCC cells.This study provides new theoretical support for dealing with chemotherapy resistance in esophageal cancer.Ovarian cancer is the third most common gynecological malignancy and ranks first in death rate among tumors in female reproductive system.Due to the small size and special location of the ovary,it is difficult to detect early ovarian lesions with routine gynecological physical examination.In addition,patients with ovarian cancer have no obvious symptoms in the early stage.Therefore,about 70%of patients with ovarian cancer have advanced to advanced stage when diagnosed.The occurrence and development of ovarian cancer are related to many factors,and its specific mechanism remains to be further studied.Long-chain non-coding RNA(LncRNA)is a type of small-molecule RNA with a length of more than 200 nucleotides and no protein coding ability.Increasing studies showed that LncRNA plays a vital role in many diseases including tumors,but the mechanism of LncRNA in the occurrence and development of ovarian cancer is still unclear.In this research,we performed RNA-seq for 5 pairs of ovarian primary tumors tissues and their matched metastatic tumor tissues.The data showed that the expression level of LncRNA LOC101927476 was much lower in metastatic tumors,which was further confirmed in another 22 patients with metastatic ovarian tumors.Cell functional experiments showed that LOC1 01927476 inhibit the invasion,migration and proliferation of ovarian cancer cell lines.Mechanistically,LOC101927476 was positively correlation with zinc finger transcription factor GATA4 in transcription level.RT-PCR result showed that LOC101927476 promote the transcription of GATA4.Therefore,we speculated that LOC101927476 may affect the malignant phenotype of ovarian cancer by regulating the expression of GATA4.