The Role Of USP13 In Oral Squamous Cell Carcinoma And Its Molecular Mechanism

Part one: the expression of usp13 in oral cancer and its correlation with prognosisObject: To study the expression of usp13 in oral squamous cell carcinoma(OSCC)and its relationship with clinicopathological parameters and prognosis.Methods: Ninety-five cases of primary OSCC tumor were collected,and the normal mucosal tissues were collected as control.Trizol method was used to extract total RNA from tumor tissue and paracancer tissue respectively,and reverse transcribe it into c DNA.Usp13 specific primers were synthesized according to usp13 genome sequence,and the expression level of usp13 m RNA in tumor tissue and normal mucosa tissue was detected by fluorescence quantitative PCR with 5S RNA as internal reference.SPSS25.0 software was used for statistical analysis.Chi square test was used to analyze the relationship between usp13 expression and clinicopathological indexes.Nonparametric statistics was applied to those who were not suitable for chi square statistics.Kaplan Meier survival analysis were used to draw the survival curve and analyze the prognosis.The disease-free survival period was calculated from the date of diagnosis to the time when local recurrence,distant metastasis or death were clearly proved.All statistical analysis was bilateral,P < 0.05 was statistically significant.Results: in 95 cases of OSCC,the expression of usp13 in cancer tissue was significantly decreased by fluorescence quantitative PCR and immunohistochemistry.The patients were divided into high expression group and low expression group according to the median of fluorescence quantitative PCR,54 of them were low expression group and 41 of them were high expression group.The expression of usp13 was not related to gender,tumor size(T stage),cervical lymph node metastasis(N stage)and alcohol consumption(P> 0.05);it was related to age(P= 0.1001),primary site of tumor(P = 0.001),degree of tissue differentiation(P= 0.011),clinical stage(P=0.031)and smoking(P= 0.034).The decrease of usp13 expression was mainly found in smokers younger than 60 years old,primary tumors of oropharynx or laryngopharynx,tumors of low differentiation and stage III-IV OSCC patients.The decreased expression of usp13 was correlated with the prognosis of OSCC(P < 0.01).Conclusions: the decreased expression of usp13 in OSCC is an important factor in the development of OSCC and plays a role of tumor suppressor protein.Part two: the mechanism of the effect of USP13 expression level on the physiological function of OSCCObject: Recent studies have shown that ubiquitin-specific peptidase 13(USP13),a deubiquitinase,serves as an important regulator of tumorigenesis.However,the biological role of USP13 in oral squamous cell carcinoma(OSCC)remains enigmatic.Methods: We examined USP13 expression in OSCC tissues and adjacent normal tissues by immunohistochemical staining.The biological functions of USP13 in OSCC cells and the possible underlying mechanisms were investigated.Results: In this study,we showed that USP13 expression was frequently reduced in human OSCC specimens and that the reduction was correlated with the clinical stage.Functional studies demonstrated that overexpression of USP13 suppressed OSCC cell proliferation,glucose uptake and lactate production in vitro and inhibited tumor growth in vivo.Furthermore,USP13 overexpression induced PTEN(phosphatase and tensin homolog deleted on chromosome 10)expression and repressed the activation of AKT as well as the expression of the downstream effectors glucose transporter-1(GLUT1)and hexokinase-2(HK2).Overexpression of PTEN reversed the USP13-knockdown-induced glucose uptake,lactate production,AKT activation and expression of GLUT1 and HK2.Conclusions: Our findings suggest that USP13 serves as a tumor suppressor by regulating the PTEN/AKT signaling pathway in OSCC cells,improving our understanding of OSCC progression and providing a clue for the development of a novel cancer therapy.