The Impact Of Obesity On Development And Progression Of Gastric Cancer And It's Underlying Mechanism

PART1Background and objectiveAtrophic gastritis,intestinal metaplasia,and gastric dysplasia are histologic premalignant lesions found to be multistep cascade precursors of gastric carcinogenesis.Of these lesions,gastric dysplasia(especially gastric high-grade dysplasia)might be the last stage before GC development.Approximately 85%of all patients with gastric dysplasia progress to GC annually,however,the risk factors for gastric dysplasia are not well characterized.Obesity is defined as "abnormal or excessive fat accumulation to the extent that health is impaired",and it is the fastest growing lethal disease in the Western and developing worlds.The World Health Organization(WHO)estimated that more than 1.9 billion adults,18 years old and older,were overweight worldwide in 2014.Of these individuals,over 600 million were obese.Obesity is associated with increased risks of various types of cancer including breast,endometrium,ovary,colorectal,oesophageal,liver,gallbladder,pancreatic,kidney,and stomach cancer.The relationship between obesity and GC was implicated through the positive association with cardia GC(but not non-cardia GC)observed in several meta-analyses.Obesity was also related to an increased risk of early GC(both cardia and non-cardia cancers)in a recent case-control study.High serum cholesterol levels are a major risk factor for cardiovascular disease.In addition,prospective and cross-sectional studies have suggested that an association exists between low serum cholesterol levels and subsequent cancer mortality.Subsequently,low serum cholesterol levels were found to be an independent risk factor for GC,especially intestinal-type GC.However,the effects of obesity and serum cholesterol levels on the incidence of gastric dysplasia have not been well elucidated.We conducted a retrospective investigation among Chinese adults to determine the relations between body mass index(BMI),an acceptable proxy for thinness and fatness,and the risk of gastric dysplasia.The association of serum total cholesterol level and the risk of gastric dysplasia was also examined.To determine whether BMI or serum total cholesterol level was related to the risk of gastric dysplasia at different sites such as gastric cardia or non-cardia dysplasia,subgroup analysis was performed.MethodsA case-control study was conducted to explore the relations of obesity or serum total cholesterol level with gastric dysplasia in china.A total of 893 consecutive patients with gastric dysplasia(537 males and 356 females)and 902 controls(543 males and 359 females)were enrolled at Peking union medical college hospital from January 2000 to October 2015.Odds ratios(ORs)were calculated with 95%confidence intervals(CI),including multivariate analysis.Results:After adjusted for age,alcohol consumption,smoking status,family history of GC or esophagus cancer and serum total cholesterol level,obesity(BMI,27.5-29.9)was significantly related to excess risks of gastric dysplasia in both males and females[in males,adjusted OR was 1.87(95%Cl,1.24-2.81);in females,adjusted OR was 2.72(95%CI,1.44-5.16)].In addition,higher serum total cholesterol level was associated with increasing risk of gastric dysplasia in females[adjusted OR for gastric dysplasia,1.63(950%,1.19-2.23)?ConclusionIncreased body-mass index was associated with increased risk of gastric dysplasia in both males and females.Additionally,higher serum total cholesterol level was proved to increase risk for gastric dysplasia in females.PART 2Background and objectiveGastric cancer(GC)was the fifth most common cancer and the third leading cause of cancer related mortality worldwide with an overall 5-year survival rate of approximately 20%.Especially prevalent in many Asian countries,many GC patients were diagnosed at an advanced disease stage and were treated with palliative chemotherapy,presenting median survival times of less than 2 years.To improve early diagnosis and targeted treatments of GC,an in-depth characterization of molecular underpinnings of the disease was required.It was of clinical significance to identify genes contributing to GC initiation and progression and presenting predictive value for GC diagnosis or prognosis.In a systematic study of molecular signatures in GC,AKt/PI3K/mTOR signaling pathway was found as the most frequently amplified pathway of this deadly disease.It was suggested that type I insulin-like growth factor receptor(IGF-1R)proteins were significantly overexpressed in GC tissues and proven to be an independent predictor of survival in patients with GC.IGF-1R was also evidenced to contribute to activate AKt/PI3K/mTOR signaling pathway.Since IGF-1R/AKt/PI3K/mTOR signaling was managed by spatiotemporal regulatory mechanisms,it was of interest to proof if alternative pathways might contribute to IGF-1R/AKt/PI3K/mTOR deregulation in GC.NUCKS1(nuclear,casein kinase and cyclin-dependent kinase substrate 1),located on human chromosome 1q32.1,coded a highly phosphorylated protein presented in various vertebrate cell types and tissues.NUCKS1 was a substrate for cyclin-dependent kinases,casein kinase 2,second messenger-activated kinases,and DNA-activated protein kinase.NUCKS1 had functioned in the regulation of glucose metabolism and energy homeostasis.Expression of NUCKS1 was inversely correlated with body-mass index in humans and body fat in mice.In addition,NUCKS1 was implicated in cell proliferation,cell growth,and the regulation of cell cycle especially rapidly growing cells.Interestingly,NUCKS1 has been picked up in several screens aimed at identifying biomarkers in cancers,including cervical squamous cell carcinoma,breast cancer,colorectal cancer,and hepatocellular carcinoma.Emerging evidence established MUCKS1 as a positive regulator of the insulin signaling pathway,including insulin receptor(IR)transcription.However,the potential oncogenic role of NUCKS1 and its regulatory mechanisms in malignancy has not been elucidated.The effects of nuclear ubiquitous casein and cyclin-dependent kinase substrate 1(NUCKS1)on energy homeostasis and glucose metabolism have been studied extensively,but their effects on tumor cells and relevant mechanism are less well defined.This study aimed to explore the role and mechanism of NUCKS1 in gastric cancer(GC)progression.Methods:The expression dynamics of NUCKS1 were examined using microarray-based immunohistochemistry in a group of carcinomatous and non-neoplastic gastric tissues.A series of in vitro and in vivo assays were performed to clarify the function of NUCKS1 in GC and its underlying mechanisms.Results:The overexpression of NUCKS1 was examined by immunohistochemistry in 43/100(43%)GC specimen,which was higher than that in adjancent non-tumor tissues(11 of 9012.2%,P<0.001).Overexpression of NUCKS1 was also significantly related to invasive phenotype of GC and determined to be an indisputable predictor of shortened survival.Depletion of NUCKS 1 in GC cells significantly induced cells apoptosis and reduced cells proliferation and invasiveness in vitro.Additionally,ectopic overexpression of NUCKS 1 in GC cells enhanced GC cell proliferation and invasion in vitro and promoted tumor growth in vivo.RNA interference was used to knock down IGF-1R expression in AGS-NUCKS1 cells.After si-IGF-1R treatment,transwell assays indicated that the migratory and invasive capacities of AGS-NUCKS1 cells were all dramatically inhibited.In addition,after the silencing of IGF-1R in AGS-NUCKS1 cell lines,CCK-8 assay revealed that cell proliferation was substantially reduced,cell-cycle analysis showed an increase of cells in G0/G1 phases companied by a significant reduction of cells in S phase,and Annexin V-FITC/PI assay demonstrated an increased rate of cell apoptosis.Western blotting identified that the expression levels of MMP-2 and MMP-9 were remarkably reduced after depletion of IGF-1R in AGS-NUCKS1 cell lines,while KLF4 was not significantly differentThe western blot results showed that NUCKS 1 depletion significantly reduced expression levels of IGF-1R,phospho-Akt(Ser473),PI3K,mTOR,and phospho-mTOR(Ser2448)in both SGC-7901 and NCI-N87 cell lines,but pan-Akt and phospho-Akt(Thr308)only in NCI-N87 cell lines.Additionally,we found that overexpression of NUCKS 1 led to a significant increase in IGF-1R,phospho-Akt(Ser473 and Thr308),PI3K,mTOR,and phospho-mTOR(Ser2448)levels in AGS cell lines.After si-IGF-1R treatment,NUCKS1-induced activation of PI3K/AKT/mTOR signaling pathway was inhibited,as evidenced by the decreased expressions of pan-Akt,phospho-Akt(Ser473 and Thr308),PI3K,mTOR,and phospho-mTOR(Ser2448).In addition,IGF-1R was found to be overexpressed in GC tissues compared with adjacent non-tumor specimens using immunohistochemical staining,and a significant positive correlation between the overexpression of NUCKS1 and IGF-1R was evaluated in our large cohort of GC tissues r=0.6237,P<0.001).Subsequently,dual-luciferase reporter assay suggested that overexpression of NUCKS1 led to increased IGF-1R transcription,whereas control vector failed to induce the IGF-1R promoter(P=0.011).Conclusion:Our research describes the expression pattern of NUCKS1 in human GC and the overexpression of NUCKS1 may be crucial in the acquisition of aggressive and poor prognostic phenotype of this malignancy.Additionally,functional and mechanistic studies of NUCKS1,as provided in the current study,demonstrate a critical role of NUCKS1 in the control of cell invasiveness and proliferation by regulating PI3K/Akt/mTOR signaling pathway and IGF-1R was vital for NUCKS1-mediate PI3K/Akt/mTOR signaling pathway activation.Altogether,NUCKS1/IGF-1R/PI3K/Akt/mTOR signaling pathway might hold immense promise as a potent anticancer strategy in GC.PART 3Background and objective:To evaluate the prognostic effects of neoadjuvant chemotherapy(NAC)in patients with local advanced gastric cancer.Methods:We retrospectively analyzed prognosis in 180 advanced gastric cancer patients underwent neoadjuvant chemotherapy between February 2007 and March 2017.All patients were allocated a clinical tumor stage before treatment,which was compared with pathologic stage after surgical resection.Survival analysis was conducted using Kaplan-Meier analysis.Results:According to Response Evaluation Criteria in Solid Tumors,six of the 180 patients in the NAC followed by surgery group showed complete response,91 showed partial response,63 had stable disease,and 20 had progressive disease.The chemotherapy response rate was 53.9%;the disease control rate was 88.9%.Neoadjuvant chemotherapy could prolong the survival of GC patients with clinical T3-4 stages.(P=0.046 for overall survival,P=0.007 for disease-free survival).Consequently,Patients with downstaged tumors after neoadjuvant chemotherapy experienced improved survival compared with patients without response(P=0.003 for overall survival,P=0.002 for disease-free survival).Conclusion:In GC patients with clinical T3-4 stages,neoadjuvant chemotheropy could significantly improve overall and disease-free survivals.Consequently,downstaged tumors of GC after neoadjuvant chemotherapy determines better prognosis compared with the control group.