| Objective:Breast cancer is the most common malignant tumor in women worldwide.Although the incidence of breast cancer in China is lower than the global level,it is increasing rapidly year after year.It is estimated that about 45,000 Chinese females die of breast cancer per year,ranking the second cause of death of female cancer in China.Abnormal activation of the PI3K-AKT signaling pathway has been observed in cancer for more than 20 years.The PI3K-AKT signaling pathway is essential for cell cycle,proliferation,growth,survival,protein synthesis,and glucose metabolism.AKT is activated downstream of PI3 K,and p-AKT is an activated form of AKT.When AKT is activated,it can phosphorylate many of its downstream substrates,including m TOR,GSK-3,p21WAF1 and p27Kip1,Fox O transcription factor,Bcl-2,MDM2,etc.,and so as to promote cell proliferation,growth and anti-apoptosis.The PI3K-AKT signal pathway is found to be mutated in the extensive tumor spectrum,but the expression level of AKT and p-AKT in breast cancer tissues is controversial at the clinicopathological point of view(the overall level).Most studies suggest that the expression level of AKT and p-AKT in breast cancer is related to the clinical stage and histological grade of breast cancer.However,little is known about the relation between AKT,p-AKT and prognosis of breast cancer.Li Ma [1] found that the cell proliferation inhibitory gene(Mfn2)significantly promoted apoptosis and inhibited cell proliferation through PI3K-AKT signaling pathway.By searching the literatures,there not exist the researches involving the relation between Mfn2 and AKT,p-AKT expression in breast cancer.In this study,the expression of AKT and p-AKT in primary breast invasive ductal carcinoma was detected by immunohistochemistry Max Vision TM,and the relation between the expression level of AKT,p-AKT and the clinical pathology characteristics,prognosis in invasive ductal breast carcinomas are investigated.Further to reveal the significance of Mfn2 and PI3K-AKT signaling pathway in the development of breast cancer by exploring whether the expression level of Mfn2 is related to AKT,p-AKT in breast cancer tissue,so as to confirm of our preliminary work.Methods:1 This research's object was randomly recruited 126 surgical resection cases with primary breast invasive duct carcinoma paraffin embedded tissue from January to December 2008 at breast cancer center of the Fourth Hospital of Hebei Medical University which also had complete follow-up data.The expression of AKT,p-AKT and Mfn2 in breast invasive ductal carcinoma tissue was detected by Max Vision TM One Step immunohistochemical stain.2 To discuss the relations between the expression of AKT and p-AKT and the clinicopathologic features and prognosis of breast cancer,when taken into the age,the tumor size,lymph node metastasis,post-surgery TNM stage level,pathological grade,vessel tumor embolus and the level of ER,PR,HER2 and Ki-67,DFS,OS,adverse event and existing status.3 To observe the correlation Mfn2 and the expression of AKT and p-AKT in the breast carcinomas.4 Statistical analyses were performed by SPSS 19.0 software.The results of immunohistochemical stain was analyzed using Chi-square test and Spearman order correlated examination.The Kaplan-Meier survival curve was analyzed by univariate survival analysis,and the COX regression model was used for multivariate survival analysis.All statistical tests were considered significant at P<0.05.Results:1 In the 126 cases of breast invasive duct carcinoma specimens,54(42.9%)cases displayed negative of p-AKT while 72(57.1%)cases displayed positive of p-AKT,26(20.6%)cases displayed negative of AKT while 100(79.4%)cases displayed positive of AKT.In 10 cases of normal breast ductal epithelium specimens,p-AKT negative were 9 cases(9/10,90%),p-AKT positive were 1 cases(1/10,10%).There were 5 cases(5/10,50%)of AKT negative patients and 5 cases(5/10,50%)of AKT positive patients.The positive expression rate of p-AKT in breast ductus invasive ductal carcinoma was higher than that in normal breast ductal epithelium(57.1% vs 10%),?2 =6.493,P=0.011,the difference was statistically significant.The positive expression rate of AKT in breast ductus invasive ductal carcinoma was higher than that in normal breast ductal epithelium(79.4% vs 50%),?2=3.024,P=0.082,but the difference was not statistically significant.2 According to the tumor size of breast cancer,126 patients were divided into: ?2cm group(54/126,42.9%),>2cm and ?5cm group(62/126,49.2%),> 5cm group(10/126,7.9%).The positive ratio respectively shows 44.4%,62.9%,90.0%.The expression difference was of statistical significance,with ?2=8.804,P=0.012.On the basis of spearmans analysis,r=0.254,P=0.004.The expression of p-AKT was positively correlated with the size of primary tumor.3 According to the number of lymph node metastasis after surgery,126 patients were divided into: N0(no lymph node metastasis)group(57/126,45.2%),N1(1~3 lymph node metastasis)group(26/126,20.6%),N2(4~9 lymph node metastasis)group(25/126,19.9%),N3(over 10 lymph node metastasis)group(18/126,14.3%).The four group of P-AKT negative ratio respectively show 57.9%,50.0%,20.0%,16.7% while positive ratio respectively 42.1%,50.0%,80.0%,83.3%.The expression difference was of statistical significance,with ?2=16.180,P=0.001.On the basis of spearmans analysis,r =0.338,P<0.001.The expression of p-AKT was positively correlated with the number of lymph node metastasis.4 The 126 cases with primary breast cancer were divided into 3 groups according to clinical stage,stage ? group(32/126,25.4%),stage ? group(55/126,43.7%)and stage ? group(39/126,30.9%).The three groups of P-AKT negative expression rate respectively show 59.4%,52.7%,15.4% while positive expression rate respectively 40.6%,47.3%,84.6%.The expression difference was of statistical significance,with ?2 =17.772,P<0.001.On the basis of spearmans analysis,r=0.347,P<0.001.The expression of p-AKT was positively correlated with clinical stage.5 According to histological grade after surgery,the cases with primary breast cancer were divided into 3 groups: Stage ? group(0/126,0%),Stage ? group(103/126,81.7%)including the positive of p-AKT(53/103,51.5%)and the negative(50/103,48.5%),Stage ? group(23/126,18.3%)including the positive of p-AKT(19/23,82.6%)and the negative(4/23,17.4%).The data was analyzed based on Chi-squared test and the expression difference was of statistical significance,with ?2 =7.451,P=0.006.On the basis of spearmans analysis,r=0.243,P=0.006.The expression of p-AKT was positively correlated with histological grade after surgery.6 According to HER2 expression: There were 92cases(92/126,73.0%)of HER2 negative group,including 47 cases(47/92,51.1%)of p-AKT positive.34 cases of HER2 positive group(34/126,27.0%),including P-AKT positive in 25cases(25/34,73.5%).The expression of p-AKT in the two groups was analyzed by chi-square test: ?2=5.106,P=0.024,the difference was statistically significant.Suggest that the positive expression rate of p-AKT in the HER2 positive group was higher.7 According to the patients during follow-up have experienced adverse events such as the case of recurrence and metastasis,the cases w-ith breast cancer were divided into 2 groups: non-recurrence and metastasis group(83/126,65.9%),recurrence and metastasis group(43/126,34.1%).The two groups of p-AKT positive expression rate respectively show 50.6%,69.8%.The expression difference was of statistical significance,with ?2=4.248,P=0.039.Recurrence and metastasis group had a higher p-AKT positive expression rate.8 According to the survival situation by the end of follow-up,the cases with breast cancer were divided into 2 groups:living group(95/126,75.4%)and dead group(31/126,24.6%).The two groups of p-AKT positive expression rate respectively show 49.5%,80.6%.The expression difference was of statistical significance,with ?2=9.274,P =0.002.The positive expression of p-AKT hints a poor prognosis.9 The expression of p-AKT was not associated with the age of patient,vessel tumor embolus,histological grade and the expression level of ER,PR,Ki-67(P>0.05).10 The expression of AKT was not associated with the age of patient,the size of tumor,the number of lymph node metastasis,the clinical stage after surgery,vessel tumor embolus,histological grade and the expression level of PR,ER,HER2,Ki-67 as well as DFS and OS(P>0.05).11 The 5-year OS of p-AKT positive group was lower than that of p-AKT negative group(73.6%,92.6%),?2=9.461,P=0.002,the difference was statistically significant.The DFS of p-AKT positive group was lower than that of p-AKT negative group(62.5%,83.3%),?2=5.002,P=0.025,the difference was statistically significant.These two results suggest that the positive expression of p-AKT is associated with poor prognosis.12 The variables demonstrated significantly by the univariate analysis in the 5-year OS,the lymph node metastasis(P=0.033,HR=8.726),postoperative TNM clinical stage(P=0.015,HR=8.348),Ki-67 expression(P=0.026,HR=9.295),separately shows an independently prognostic risk factor,which is verified be COX's multivariate analys-is model.13 The variables demonstrated significantly by the univariate analysis in the 5-year DFS,only the lymph node metastasis(P=0.004,HR=13.324)shows an independently prognostic risk factor,which is verified be COX's multivariate analysis model.14 According to the expression of Mfn2,126 patients were divided into 4 groups: Mfn2(-)group(22/126,16.7%),Mfn2(+)group(55/126,43.7%),Mfn2(++)group(25/126,19.8%),Mfn2(+++)group(25/126,19.8%).The positive rates of p-AKT in the four groups were 76.2%,74.5%,48.0% and 12.0%,respectively.The expression of p-AKT was analyzed by Chi-square test,?2=31.569,P<0.001,the difference was statistically significant.On the basis of spearmans analysis,the results showed that r=-0.455 and P<0.001.Indicating that p-AKT expression was negatively correlated with Mfn2 expression.The high expression of Mfn2 reduced the expression level of p-AKT,suggesting that Mfn2 may be a potential tumor suppressor gene.Conclusions:1 Contrast with the normal breast duct epithelial tissue,the expression of p-AKT in breast cancer tissue increased,suggesting that p-AKT may be associated with breast cancer.2 The expression level of p-AKT was positively correlated with postoperative tumor diameter,lymph node metastasis,pathological TNM clinical stage.The positive expression rate of p-AKT was higher in histological grade ? and HER2 positive group.The larger tumor diameter,more lymph node metastasis,higher TNM clinical stage and histological grade were all suggestive of the poor prognosis.The positive expression of p-AKT was positively correlated with the degree of malignancy of breast invasive ductal carcinoma.3 The relationship between the expression level p-AKT and OS,DFS of patients with the invasive duct breast carcinomas is negative.Which shows the positive expression of p-AKT is correlated with a poor prognosis in invasive duct breast carcinomas,but it can't be an independent prognostic risk factor.4 The variables was not correlated with the expression of AKT: the age of patient,the size of tumor,the number of lymph node metastasis,the clinical stage after surgery,vessel tumor embolus,histological grade,the expression level of PR,ER,Ki-67,HER2 and DFS,OS(P>0.05),which hints the prognosis is nothing with the expression of AKT.5 The negative correlation between the expression of Mfn2 and p-AKT.Shows the high expression of Mfn2 depressed the level of p-AKT,which reveals the gene of Mfn2 may be the potential therapeutic target in the treatment of breast carcinomas. |
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