The Primary Research On The Expression And Action Mechanism Of GGPPS In Lung Adenocarcinoma

Background and Objection:Lung cancer remains the leading cause of cancer-related deaths worldwide in spite of recent advancements in the diagnosis and treatment in this field.Lung cancer is divided into non-small-cell lung cancer(NSCLC)and small cell lung cancer(SCLC).NSCLC accounts for 80-85%of all lung cancers,which includes three main subtypes,adenocarcinoma,squamous cell carcinoma and large-cell carcinoma.The most common type of lung cancer is adenocarcinoma which comprises around 40%of all lung cancer.NSCLC patients often relapse and develop metastases after surgery,target therapy,chemotherapy,and/or radiation therapy,resulting in an overall five-year survival rate of less than 18%.Therefore,understanding the molecular mechanisms underlying NSCLC progression,identify novel biomarkers and thera-peutic target are crucial to improve the prognosis of NSCLC patients.Geranylgeranyl diphosphate synthase(GGPPS)is an important branch point enzyme in the mevalonate metabolic pathway which can utilize FPP to synthesize GGPP.FPP and GGPP are critical intermediates of mevalonate pathway,which can make the proteins containing CaaX motif farnesylated and geranylgeranylated re-spectively.Protein prenylation is an important posttranslational modification which includes protein farnesylation and geranylgeranylation.Proteins undergoing prenyla-tion include Ras and Ras-related small GTP-binding proteins.The attachment of hydrophobic prenyl groups can anchor the proteins to cellular membranes and trigger downstream cell signaling pathway,which participates into various aspects of cellu-lar physiology and pathology.The abnormal expression of GGPPS may influence the relative content of FPP and GGPP,thus break the balance of protein farnesylation and geranylgeranylation,further participate in regulating many disease including cancer,cardiovascular diseases,and metabolic diseases,etc.Study showed that GGPPS expression was upregulated in hepatocellular carcinoma and was correlated with tumor stage,vessel invasion,and early recurrence.Further study showed that inhibition of GGPPS could lead to suppression of breast cancer cell migration.However,research on GGPPS in lung cancer is still limited.In the current study,GGPPS expression was detected in lung adenocarcinoma,and its relationship with clinicopathological characteristics and prognosis of patients was assessed.The regulatory roles of GGPPS on cell proliferation,apoptosis,migra-tion and invasion of lung adenocarcinoma cells were also analyzed and the primary potential molecular mechanism was evaluated.Our findings reveal some of the bio-logical roles of GGPPS in the occurrence and progression of lung adenocarcinoma.GGPPS may thus be considered an independent biomarker for the prognosis of lung adenocarcinoma,and a potential therapeutic target.The aim of this study was to pro-vide the theoretical basis for pathogenesis and therapeutic target of lung adenocarcinoma.Methods1.GGPPS expression detection in primary lung adenocarcinoma tissues and the relationship with clinicopathological characteristics and prognosis of lung ade-nocarcinoma patientsWe first examined GGPPS mRNA expression between lung adenocarcinoma and normal pulmonary samples in the publicly available database oncomine(www.oncomine.org).Then,we analyzed GGPPS mRNA and protein expression in clinical lung adenocarcinoma tissues and matched adjacent non-tumoral lung tissues using quantitative reverse-transcription polymerase chain reaction(qRT-RCR)and Western blotting(WB).Furthermore,we detected the protein expression of GGPPS using IHC in tissue microarray(TMA).We assessed the relation of GGPPS protein expression(staining scores)with clinicopathological parameters(i.e.,stage,lymph node metastasis)to assess its clinical significance.We further analyzed the associa-tion between GGPPS protein and the prognosis of patients with lung adenocarcinoma using Kaplan-Meier survival analysis.2.Study the biological role and potential mechanism of GGPPS in lung adeno-carcinoma cellsThe effect of GGPPS on cell proliferation was evaluated by MTT and colony formation assay.Transwell assay and wound-healing assay were employed to study the effect of GGPPS on cell migration and invasion.Flow-cytometric analysis was used to detect cell apoptosis.The primary potential molecular mechanism was ex-plored.Results:1.GGPPS overexpression in primary lung adenocarcinoma tissues and the rela-tionship with clinicopathological characteristics and prognosis of lung adenocarcinoma patientsThe datas from oncomine database,clinical lung adenocarcinoma tissues and TMA all showed that the expression of GGPPS in lung adenocarcinoma tissue was significantly higher than adjacent normal lung tissues.Moreover,GGPPS overex-pression was significantly correlated with larger tumors,lymph node metastasis,higher TNM stages and poor prognosis in lung adenocarcinoma patients2.Study the biological role and potential mechanism of GGPPS in lung adeno-carcinoma cellsModulation of GGPPS expression affected migration and invasion of lung ade-nocarcinoma cells and GGPPS regulated the lung adenocarcinoma cell migration in part through its influence on tumor EMT.However,neither downregulation nor up-regulation of GGPPS influenced the growth and apoptosis of lung adenocarcinoma cells.ConclusionOur current study is the first to show that the expression of GGPPS was re-markably upregulated in lung adenocarcinoma tissues compared to adjacent normal lung tissues.Furthermore,the increased expression of GGPPS was significantly as-sociated with larger tumors,lymph node metastasis,higher TNM stages and poor prognosis in lung adenocarcinoma patients.GGPPS regulated the lung adenocarci-noma cell migration in part through its influence on tumor EMT.However,neither downregulation nor upregulation of GGPPS influenced the growth and apoptosis of lung adenocarcinoma cells.