FASN Influence The Radiosensitivity And Radiation Induced DNA Damage Repair In Lung Cancer

Background and Purpose In recent years,lung cancer has been a leading cause of mortality worldwide;Despite improved laboratory diagnosis,surgery,chemotherapy and radiotherapy techniques,the 5-year survival rate and prognosis of patients with SNCLC remain unfavorable.It become a significant threat to human health.Radiotherapy is an important local and regional therapeutic technique.The role of ionizing radiation in radiotherapy is the induction of DNA double-strand breaks(DSBs)and inhibition DNA repair.In recent years,with the continuous development of genetic engineering and molecular biology,the basic research of tumor has been deepened,and the surgical treatment,radiotherapy and chemotherapy have become the bottleneck.Therefore,individual gene therapy has become a hot research topic at present,so it is of great significance to target the gene therapy for lung cancer.On this basis,the combination of targeted gene therapy and radiation therapy can improve the ability of ray to kill tumor cells.Ultimately benefit the patient's survival.FASN is the pivotal enzyme required for the de novo synthesis of fatty acids and represents one of the most commonly overexpressed lipogenic enzymes,which are critical to fatty acid synthesis and metabolism;this is thought to be essential for the progression,metastasis,and drug and radiation resistance of tumors.In recent years,accumulating evidence has demonstrated that the overexpression FASN is strongly linked to unfavorable prognosis and treatment resistance in a variety of human neo-plasms,including breast cancer,bladder cancer,nasopharyngeal carcinoma,esophageal cancer and pancreatic cancer.In tumor cells,owning to rapid proliferation in tumor cells,the demand for energy is greater,and the supply of endogenous fatty acid is insufficient to meet the needs of rapid proliferation of tumor tissue.Objective The goal of the project is to study the effects of FASN gene siliencing mediated by sh RNA on radiosensitivity of non-small cell lung cancer.Methods: The vector-based sh RNA plasmid(FASN-sh RNA)was transfected into NSCLC A549 cell line to silence FASN gene expression.The efficiency of FASN silencing was determined by RT-PCR and Western blot techniques.The survival rate of A549 was examined by CCK-8 assay.The radiosensitivity of A549 cell to X-ray was examined by colony formation assay.Cell cycle distribution and the proportion of apoptotic cells were detected by flow cytometry.DNA damage's repair of A549 was determined by Western blot.Results A549 cells transfected with FASN-sh RNA had dramatically decrease levels of FASN compared to NC groups at both m RNA and the protein level.Knockdown of FASN decreased the proliferation of A549 cells.Knockdown of FASN increased the sensitivity of A549 cells to radiation.Knockdown of FASN and combined with 6Gy X-ray increased the proportion of G2/M increased significantly.Knockdown of FASN and combined with 6Gy X-ray promotes radiation –induced apoptosis.Knockdown of FASN resulted in the downregulation of DNA-PKcs to decreased the DNA damage repair ability.Conclusions Lentivirus-mediated sh RNA can silenced FASN gene expression,attenuate the proliferation,induce the apoptosis and alter the distribution of cell cycle in A549. FASN-sh RNA combined with radiation can enhance the radiosensitivity of A549 cells.Its mechanism is correlated with increase G2/M arrest,increase apoptosis and attenuate DNA damage repair capacity.