CXCL8 is essential for cervical cancer cell acquired radioresistance and acts as a promising therapeutic target in cervical cancer

Background Acquired radiotherapy resistance represents a significant challenge in the radiotherapy management of cervical cancer. Acquired radiotherapy-resistant cervical cancer cell strains established by mimicking clinical treatment patterns are rarely reported. Furthermore, the pro-tumour chemokine, CXCL8, has been demonstrated to be closely related to the development, prognosis and resistance of numerous cancers. Nevertheless, a comprehensive study of the role of CXCL8 in cervical cancer is currently absent. Methods Two distinct acquired radiotherapy-resistant CC cell strains were established through repeated intermittent irradiation, mimicking clinical treatment patterns and radiotherapy resistance of the cell strains validated by cell proliferation, plate clone formation, apoptosis, cell cycle distribution, and invasion experiments. The differential mRNAs of two different types of resistance strains and the parental strains were employed by mRNA-seq, intersected with Venn diagram and verified by qRT-PCR. Then,bioinformatics analysis was conducted through the public database of cancer radiosensitivity regulation factors to investigate key genes involved in radiotherapy resistance in CC. Finally, CXCL8 was identified as a critical regulator of acquired radiotherapy resistance. In vitro, assays of cell viability, clone formation, apoptosis and cell cycle were conducted following transient transfection of cervical cancer radiotherapy-resistant cell strains Hela-RR and Siha-RR with knockdown of CXCL8, as well as subsequent addition of exogenous CXCL8 to cervical cancer parental cell strains Hela and Siha. Results The cervical cancer radiotherapy-resistant cell lines Hela-RR and Siha-RR cells were successfully established by simulating clinical treatment protocols through radiation irradiation; and the cell proliferation assay, plate clone formation assay, and cell cycle distribution assay proved that the Hela-RR and Siha-RR cells have a certain degree of resistance to radiotherapy.The mRNA high- throughput sequencing technology was used to successfully establish the differential mRNA expression profile of acquired radiotherapy resistance in cervical cancer. Venn diagram,taking intersection of differential mRNA groups, found out 50 mRNA co-up-regulated in Hela-RR and Siha-RR cells and 54 mRNA co-down-regulated in Hela-RR and Siha-RR cells. The differential mRNA of Hela-RR and Siha-RR compared with the differential mRNA of the TOP10 of the differential mRNA genes: IL 11, CXCL 8, MMP 1, HSPA 8, CA9, PPFIA4, EDN 2, GUCY1A2, EFNA 3, TNFAIP 6.The mRNA difference levels of HSRNA 8, TNFAIP6, CXCL 8, and PPFIA4 in Hela-RR and Hela, Siha-RR and Siha cells were verified by qRT-PCR. A total of 96 differentially expressed CRRF, after univariate cox regression and LASSO-cox to remove redundant genes, finally acquired the TOP8 key genes CXCL8, IFI 30, HK2, SPP 1, IGF1, PAX 9, SLC22A3, and ABCB1. Then we surmise that the key genes of radiosensitivity regulators analysed by informatics were screened to identify the target CXCL8 for potential reversal of radiotherapy resistance.GEPIA2 combined with immunohistochemistry showed that the expression of CXCL8 in cervical carcinoma was higher than that in paracancerous tissues. In vitro ,Knockdown of CXCL8 enhances radiotherapy sensitivity in acquired radioresistant cervical cancer cell strains (Hela-RR and Siha-RR) and addition of exogenous CXCL8 induces radiotherapy resistance in the parental cell strains (Hela and Siha).