Mechanisms Of HPV DNA In The Cytoplasm Of Cervical Cancer Cells Participating In The Formaotion Of Tumor Microenvironment By Acting STING

Background: In most malignant tumors,tumor and precancerous cells can use various mechanisms to avoid the identification and destruction of the immune system and regulate the microenvironment of tumors to allow tumors to occur and grow.In recent years,most researchers believe that the integration of HPV gene into the host genome is the key step in the occurrence and development of cervical cancer.However,free HPV DNA still exists in the cytoplasm of cervical cancer cells,suggesting that the free HPV DNA may be involved in the regulation of the microenvironment of cervical cancer cells.Stimulator of IFN genes(STING)is a crucial junction protein in the downstream of cytoplasmic DNA receptors,which plays an important role in sensing cytoplasmic abnormal DNA and immune defense.Activated STING can not only induce the release of type I interferon,but also other cytokines,such as interleukin 6(IL-6),IL-6,interleukin 10(IL-10),indoleamine 2,3-dioxygenase(IDO),chemokine 22(CCL22).Therefore,many researchers also indicate that STING may be anotherimportant target for cancer treatment.But the expression of STING in cervical cancer and its role in the occurrence and development of cervical cancer are still unclear.Objectives: The purpose of this study was to observe the expression of STING and related immunosuppressive factors in HPV-positive cervical squamous cell carcinoma(CSCC)and precancerous lesions,and to explore their role in the progression of CSCC and the regulatory mechanism of tumor microenvironment.Methods: 58 specimens of cervical tissue were collected,20 cases of normal cervical tissue were used as control group,9 cases of HR-HPV positive cervical intraepithelial neoplasia III(CIN III)and 9 cases of CIN II as precancerous lesion group,and 20 cases of CSCC as CSCC group.The expression of STING protein in cervical tissues was detected by Western-blot and the expression of STING,CCL22,IDO and IL-10 mRNA in cervical tissues was detected by qRT-PCR.Western blot and qRT-PCR were used to detect the expression of STING in normal and four cervical cancer cell lines.Then the activation of STING was observed by cell immunofluorescence technique after transfection of poly(dA: dT).Finally,siRNA was transfected for interference experiment and qRT-PCR was used to detect the expression of IFNβ,CCL22,IDO and IL-10.Result: The expression of STING protein in cervical lesions was significantly higher than it in normal cervical tissue,and its expression innormal cervix,CIN II-III and CSCC increased gradually.The expression of STING,CCL22,IDO and IL-10 mRNA in cervical lesions was significantly higher than that in normal cervix,and the expression level increased with the progression of lesions.In cervical lesions,the expression of STING mRNA was positively correlated with CCL22 mRNA and IDO mRNA.Moreover,cell experiments showed that the expression of STING in HPV-positive cervical cancer cell lines was significantly up-regulated at both the level of protein and mRNA,and the STING could be activated by poly(dA: dT)in the cytoplasm and turn to promote the formation of IDO.Conclusion: Free HPV DNA in the cytoplasm of cervical cancer cells can induce the release of IDO by activating STING with high expression,and thus participates in the establishment of microenvironment of cervical cancer and promotes the process of cervical cancer.