Clinical And Experimental Study On The Relationship Between Hyperglycemia And Gastrointestinal Stromal Tumor

Objective: Gastrointestinal stromal tumor(GIST)is a subtype of mesenchymal tumors and is widely believed to originate from the interstitial cell of Cajal(ICC).A recent study revealed that hyperglycemia could stimulate ICC hyperplasia via ERK1/2-ETV1-KIT pathway.However,it’s not clear whether there is correlation between hyperglycemia and GIST.The present study aimed to explore the relationship between hyperglycemia and GIST and its potential mechanism through clinical and experimental study.Methods:(1)We retrospectively analyzed clinical records of 858 patients who underwent endoscopic treatment for gastric submucosal tumors(SMT)in the Digestive Endoscopic Center of Tianjin Medical University General Hospital from June 2008 to June 2017.The endoscopic features of different types of gastric SMT were studied to select the appropriate groups as controls.The correlation between hyperglycemia and GIST was explored by further analysis of clinical features of GIST patients and controls.(2)Specimens of gastric GISTs and leiomyomas resected under endoscopy were collected and were divide into hyperglycemia group and normal group according to the patients’ fasting blood glucose(FBG),glycosylated hemoglobin level and history of diabetes mellitus(DM).The expression levels of ERK1/2,P-ERK1/2,ETV1 and KIT in tumor tissues were detected by immunohistochemistry and Western blot.(3)GIST882 cells were maintained for 72 hours in the presence of 100mg/d L,180mg/d L,450mg/d L,900mg/d L,1800mg/d L or 4500mg/d L glucose,named G100,G180,G450,G900,G1800 and G4500 respectively.In the control cultures,glucose levels greater than 100 mg/d L were replaced with equimolar concentrations of the metabolically inert sugar alcohol mannitol.The viable cell count was detected by CCK-8 test.Ki67 was detected by immunocytochemistry.ERK1/2,P-ERK1/2,ETV1 and KIT were detected by Western blot.In order to verify the effect of ERK1/2 phosphorylation on GIST882 cells,G100 and G450 groups were treated with U0126(10μM)and maintained for 72 hours.The viable cell count and the ERK1/2,P-ERK1/2,ETV1,and KIT were examined.Results:(1)The gender distribution,body mass index(BMI),proportion of hypertension and type 2 diabetes,duration of hypertension,FBG and other laboratory test results between patients with GIST and patients with leiomyoma were not statistically different(P>0.05).However,patients with GIST were elder(P <0.001)and had a longer duration of DM than those with leiomyomas(P<0.05).Multivariate logistic analysis showed that GIST was associated with longer duration of DM(OR=1.012,P<0.05)regardless of age(OR=1.056,P>0.05).The FBG was positively correlated with tumor size(r=0.164,P<0.01)of GIST,while it was not correlated with that of leiomyoma(r=-0.032,P>0.05).There was no correlation between BMI and tumor size of neither GIST nor leiomyoma(P>0.05).(2)Among 26 GISTs,15 were in normal group and 11 were in hyperglycemia group.All of them were at very low/low risk.Protein levels of KIT(P<0.05),ETV1(P<0.05),and P-ERK1/2(P<0.01)in GIST were higher in the hyperglycemia group than normal group while ERK1/2 protein expression was not statistically different(P>0.05).ETV1 and KIT were hardly detected in leiomyoma while phosphorylation level of ERK1/2 showed no statistical differences between normal and hyperglycemia groups in leiomyoma.(3)The viable cell count,ERK1/2 phosphorylation,ETV1 and KIT levels in GIST882 increased in concentration-dependent manner in experimental group,with maximum stimulation occurring in G450 group,which were statistically different from the G100 group(P<0.001,P<0.01,P<0.01,P<0.001,respectively).The positive rate of Ki67 in the G450 group was also higher than that in the G100 group(P<0.05).After treated with U0126,the phosphorylation level of ERK1/2 in G450+U0126 group was significantly lower than that in G450+DMSO group(P<0.001),and the viable cell count decreased(P<0.001),while ETV1(P<0.01)and KIT(P<0.001)protein levels were also significantly down-regulated.The level of P-ERK1/2 ETV1,KIT and the viable cell count in G100+U0126 group were lower than those in G100+DMSO group,but were not statistically different(both P>0.05).Conclusion: The FBG is positively correlated with the tumor size of GIST,and is a risk factor for the risk stratification of GIST.Hyperglycemia can up-regulate phosphorylation of ERK1/2 in GIST at low-risk/very low-risk with increased expression of ETV1 and KIT.High concentration of glucose can promote GIST882 cell proliferation through the ERK1/2-ETV1-KIT pathway.