Experimental Study Of STAT3 As A New Tumor Marker Of Lung

Objective:To investigate the expression of STAT3(signal transducer and activator of transcription 3),CEA(carcinoembryonic antig- en) and CA125(carbohydrate antigen) in lung adenocarcinoma cell A549 and human normal lung cell MRC-5,analyze their relationship in lung adenocarcinoma cell A549,explore the value of STAT3 on early diagn- osis of lung cancer and the possibility as a new tumor marker. Methods:1,Used the electrochemiluminescence to detect the level of CEA and CA125 in medium which culture lung adenocarcinoma cell A549 and human normal lung cell MRC-5 3 days. 2,Expression of protein of STAT3,CEA and CA125 in lung adenocarcinoma cell A549 and human normal lung cell MRC-5 was tested by immunohistochemistry staining (PV). The pictures were analyzed by Image-Pro Plus version 6.0 (IPP 6.0) professional image analysis software .The degree of stain was determined by mean optical density(MOD) of sections. The correlation between STAT3 and CEA or CA125 in lung adenocarcinoma cell A549 was analyzed . 3,Relative expression of mRNA of STAT3,CEA and CA125 in lung adenocarcinoma cell A549 and human normal lung cell MRC-5 was tested by real time PCR and the correlation between STAT3 and CEA or CA125 in lung adenocarcinoma cell A549 was analyzed .Results: 1,The result of the electrochemiluminescence: The expression of CEA,CA125 in lung adenocarcinoma cell A549 , s medium were apparently higher than that in human normal lung cell MRC- 5,.After statistical analysis, they had statistically significant difference. 2,The results of the immunohistochemistry : (1)The protein levels of STAT3,CEA and CA125 in lung adenocarcinoma cell A549 were apparently higher than that in human normal lung cell MRC-5.After statistical analysis, they had statistically significant difference (P< 0.01).(2) The protein level of STAT3 was in a positive correlation with CEA in lung adenocarcinoma cell A549 (r =0.583,P=0.007,P<0.01).(3) The protein level of STAT3 was in a positive correlation with CA125 in lung adenocarcinoma cell A549 (r=0.721,P=0.000,P<0.01).3,The results of the real time PCR: (1)The PCR products of STAT3,CEA,CA125 and GAPDH were specific.The PCR efficiency of STAT3,CEA,CA125 and GAPDH were 96.97%,98.71%, 95.17%and 96.76%separately.(2)The mRNA levels of STAT3,CEA and CA125 in lung adenocarcinoma cell A549 were apparently higher than that in human normal lung cell MRC-5.After statistical analysis, they had statistically significant difference (P<0.05).(3) The mRNA level of STAT3 was in a positive correlation with CEA in lung adenocarcinoma cell A549 (r = 0.521,P= 0.047,P<0.05).(4) The mRNA level of STAT3 was in a positive correlation with CA125 in lung adenocarcinoma cell A549 (r=0.814,P= 0.000,P<0.01).Conclusion: The protein and mRNA level of STAT3,CEA and CA125 in lung adenocarcinoma cell A549 were apparently higher than that in human normal lung cell MRC-5. The protein and mRNA level of STAT3 was in a positive correlation with CEA and CA125 in lung adenocarcinoma cell A549. STAT3 can be served as a new marker of lung cancer and be recommended for clinical use.