Cancer-associated Fibroblasts Promoted Proliferation Of Nasopharyngeal Carcinoma Post Irradiation Via NF-κB Pathway

BackgroundNesopharyngeal carcinoma(NPC)is common in southeast Asia and north Africa,which causes nearly 50,000 cases of death annually.In China,NPC is prevalent in Guangdong province.Radiotherapy(RT)as an effective tool plays a vital role in local treatment for NPC.Recently,the advancement of cancer management significantly improved the outcome of NPC patients.However,patients with recurrent and(or)metastatic events usually get a worse prognosis,which are the main causes of death.Tumor microenvironment(TME)has been found as a major participant in the biological plasticity of tumor.Being one of the most abundant stromal cells,cancerassociated fibroblasts(CAFs)contribute to all aspects of cancer progression,including tumorigenesis,invasion,distant metastasis,angiogenesis,chemotherapy tolerance and escape of immunity.To date,radiobiological researches regarding to CAF and NPC remain to be uncovered.ObjectiveTo preliminarily explore the impact of CAF on the proliferation of NPC post irradiation and provide evidence for the further clinical efficacy.MethodImmunohistochemistry(IHC)assay was performed to detect the abundance of CAF in radiosensitive and radioresistant NPC carcinoma tissue,respectively.CAF and matched non-malignant fibroblasts(NF)were extracted from tumor or relative normal tissue via technology of primary culture.Next,condition medium(CM)produced by CAF and NF as well as blank culture were added to NPC cancer cells after 2Gy does of radiation,respectively.Further,CM from CAF and NF were applied for the detection of differential cytokine via liquid-phase solid-state chip technology.Colony assay and western blotting assay were used to evaluate the effect of selected cytokine on the induction of radiation-resistance and proliferation of NPC.Real time quantitative polymerase chain reaction(RT-PCR),cell counting,immunofluorescence,comet assay as well as animal experiment were performed to evaluate the effect of tranilast on CAF,including its viability and the attenuation of radiation-resistance induced by CAF.ResultCompared with control group,cells treated with CM from CAF survived more from radiation,indicating the enhanced capacity of proliferation and radiation-resistance.Hepatocellular grow factor(HGF)and interleukin-8(IL-8)were found significantly elevated in CM produced by CAF.Further research revealed that IL-8 enabled to stimulate the proliferation following radiation.NF-κB signal pathway of NPC tumor was activated evidently and DNA damage was reduced after the stimulation from CAF/CM,while the proliferation of tumor decreased after blocking the signal.Critically,the use of tranilast,an inhibitor to CAF,weakened the proliferation of NPC after irradiation as well as the characteristic of radio-resistance.ConclusionCAF activated NF-κB pathway in tumor cells via IL-8,which reduced DNA damage and promoted tumor cell proliferation and radioresistance upon radiation.Tranilast,an inhibitor of CAF,could suppress the proliferation and the property of radioresistance of NPC.