Significance Of The Expressions Of DNA Methyltransferases In Peripheral Blood From Lung Cancer Patients

Background and objectiveAt present the incidence and mortality of lung cancer has risen to the first of avariety of cancers, and due to factors such as air pollution, an ageing population, theincidence of lung cancer is still on the rise, but the present situation of the earlydiagnosis of lung cancer is not ideal, so as to form a heavier burden on society andpatients. So we need to find a better means of early diagnosis and improve thepatients survival rate. Early lung cancer often accompany epigenetic events, such asDNA methylation, DNA methyltransferase (DNA methyltransferase, DNMT) change,thus we have designed the experiment, by testing the protein levels of3kindsDNMTs in different populations, to explore the relationship between DNMTs proteinlevel change and lung cancer occurrence, development, and to provide valuableinformation for lung cancer epigenetics research and early diagnosis of lung cancer.MethodsDNMTs expression in peripheral blood from lung cancer patients (126cases)and benign lung disease patients (138cases)were tested and compared with normalcontrols(146cases) using ELISA. Gender, age, smoking, histological classificationand staing in lung cancer to be analyzed their connection with the expression of DNMTs.Results1. The results of comparing three kinds of DNMTs protein levels not inhierarchy For the peripheral blood DNMT3a, DNMT3b and DNMT1proteinlevels in lung cancer and lung benign disease group and health control group,therewere differences between the three groups of overall comparison（F=11.472,5.592,14.866, P=0.000,0.004,0.000）, specific pair of comparative, the level of the lungcancer group was obviously lower than that of health control group（all P＜0.05）,there was no statistical difference of the protein level between the lung cancer andlung benign disease group（all P＞0.05）.2. The results of comparing three kinds of DNMTs protein levels inhierarchies2.1The results of comparing DNMT3a protein levels in hierarchies Males,females,lower than60years,higher than60years, non-smokers,in these hierarchies,for the peripheral blood DNMT3a protein levels in lung cancer and lung benigndisease group and health control group,there were differences between the threegroups of overall comparison（F=5.429,4.268,8.352,4.467,10.278, P=0.005,0.016,0.000,0.014,0.000）, specific pair of comparative, the level of the lung cancergroup was obviously lower than that of health control group（all P＜0.05）, therewas no statistical difference of the protein level between the lung cancer and lungbenign disease group（all P＞0.05）.2.2The results of comparing DNMT3b protein levels in hierarchiesFemales, lower than60years, non-smokers,in these hierarchies, for the peripheralblood DNMT3b protein levels in lung cancer and lung benign disease group andhealth control group,there were differences between the three groups of overallcomparison（F=3.719,5.760,4.238, P=0.027,0.004,0.015）, specific pair ofcomparative, the level of the lung cancer group was obviously lower than that ofhealth control group（all P＜0.05）.2.3The results of comparing DNMT1protein levels in hierarchies Males, lower than60years,higher than60years, smokers,non-smokers,in these hierarchies,for the peripheral blood DNMT1protein levels in lung cancer and lung benigndisease group and health control group,there were differences between the threegroups of overall comparison（F=16.963,8.935,4.142,14.459,6.081, P=0.000,0.000,0.018,0.000,0.003）, specific pair of comparative, the level of the lung cancergroup was obviously lower than that of health control group（all P＜0.05）, therewas no statistical difference of the protein level between the lung cancer and lungbenign disease group（all P＞0.05）.3. The results of comparing DNMTs protein levels in different genders,agesand somking histories There were different influences on DNMTs protein levelsbetween groups from different genders,ages and somking histories. There weredifferences of the peripheral blood DNMT3a in lung cancer group between differentages and smoking histories（t=-2.566,2.039, P=0.011,0.044）. There was differenceof DNMT3b in lung cancer group between different age（st=-2.467, P=0.015）. Therewas difference of DNMT1in lung benign disease group between different smokinghistories（t=1.987, P=0.049）. There were differences of DNMT1in health controlgroup between different genders and smoking histories（t=2.445,3.782, P=0.016,0.000）.4. The results of comparing DNMTs protein levels in different tissue typesand clinical stages of lung cancer There were no differences of the peripheralblood DNMT3a, DNMT3b and DNMT1protein levels between tissue types in lungcancer（t=-0.377,-0.051,-1.125, P=0.707,0.959,0.263, t=-0.978,0.597,-1.061,P=0.331,0.552,0.291）. There were no differences of the peripheral blood DNMT3a,DNMT3b and DNMT1protein levels between clinical stages in lung cancer（t=-0.249,-0.368,-0.398, P=0.804,0.714,0.691）.ConclusionThe decrease of peripheral blood DNMT3a, DNMT3b and DNMT1proteinlevels was associated with lung cancer, but it needs further study that if theexpression of DNMTs could be as a biomarker in early diagnosis of lung cancer. Peripheral blood DNMT3a, DNMT3b and DNMT1protein levels has nothing to dowith histology and clinical staging of lung cancer.