Research On Association Between MTDH Gene And The Micrometastasis Of Breast Cancer By Real-time Fluorescent Quantification Polymerase Chain Reaction

Backgrounds and Objective:Breast cancer is one of the most common malignant neoplasms and the main cause of death in women. There are about 1.2 million new cases of breast cancer each year in the world, and about 250,000 women die of breast cancer annually. The incidence of breast cancer is lower in China. With the westernization of lifestyle in the recent years, however, the incidence of breast cancer in China has shown an obvious upward trend, and breast cancer in urban women has become the most common malignant tumour after lung cancer, and its mortality rate is also rising. More importantly, the mortality rate of breast cancer in female cancer is in the first place, while the Metastasis is the main reason of caused death in breast cancer patients. Currently we considered that micrometastasis being not detected before surgery or circulating tumor cells having entered into the blood is one of the major causes of postoperative metastasis, so it has important clinical value to looking for a tumor specific target marked early metastasis, which detected a sub-clinical micrometastasis in the early stage, then it has important significance in order to further explore the mechanisms of invasion and metastasis with breast cancer, and to find new treatment methods to enhance breast cancer treatment, and to improve the survival rate of breast cancer. Transfer adhesion gene (Metadherin, MTDH) is an important gene involved in tumor invasion and metastasis, and encoding genes is located in 8q22, it is also known as Astrocyte Elevated Gene-1 (AEG-1) gene. A number of studies showed that expression and regulation of the MTDH gene is related to tumor invasion and metastasis, chemotherapy resistance,tumor angiogenesis, aging, and so on. In this study, we applied real-time quantitative RT-PCR method to detect expression level of the MTDH gene in peripheral blood with breast cancer and analysis the relationship between expression level of the MTDH gene and clinicopathological features and its clinical significance.Methods:1 Total RNA was extracted from peripheral blood of breast cancer patients by centrifuge column method, and reverse transcribed into cDNA. Real-time fluorescence quantitative reverse transcription polymerase chain reaction was performed for detecting the MTDH gene expression and then correlation between MTDH gene expression and different clinicopathological features were analyzed, and relationship between MTDH gene expression and tumor proliferation related factors (PCNA and ki67) was also analyzed, in order to study relationgship between the MTDH gene expression and the prognostic index and the tumor proliferation of breast cancer; 2, Some patients with breast cancer (23 cases) was tracked and detected, and then compared MTDH gene expression level before and after chemotherapy; 3 the patients selected with breast cancer have been followed-up after treatment, then analysis the relevance of patient survival and MTDH gene expression.Results:1, The results of real-time quantitative RT-PCR showed that there have a certain amount expression of MTDH gene in peripheral blood of patients with breast cancer and other solid tumors, yet have no expression in fiberoma breast patients and healthy volunteers; 2, MTDH gene expression of 61 patients (80.3%) patients in 71 patients with breast cancer had positive result, of which 47.5%(29/61) of patients with high expression; 3, The expression of MTDH gene in breast cancer patients was correlated with lymph node metastasis, MTDH gene expression level in group of lymph node metastasis (1≤LNM≤3)was 1.548 times with in non-lymph nodes metastasis group, and MTDH gene expression level in group of lymph node metastasis (LNM> 3) was about 2.085 times with lymph node metastasis group (1≤LNM≤3), and was about 3.227 times with Non-lymph node metastasis group; 4, The MTDH gene expression in peripheral blood of breast cancer patients was related to lymph node metastasis (LNM) and TNM stages and its expression in LNM patients was 4.317 times of Non-LNM ones. Statistical significance was found betweenⅠ,Ⅱstage andⅢ,Ⅳstage (P<0.05). the MTDH gene expression of patients at IV stage was 6.774 times of patients atⅠstage, and was 3.387 times that ofⅡstage while its expression of patients atⅢstgae was 4.563 times of patients atⅠstage.; 5 The MTDH gene expression in peripheral blood of breast cancer patients was independent of the factors such as age, ER, PR andHER-2(P value was 0.784,0.164,0.154,0.577 respectively); 6, MTDH gene expression in breast cancer patients were associated with the value of tumor related factor including PCNA and Ki67 (P values were0.093 and 0.110 respectively), and were positively correlated with all positive expression of these three factors (P=0.040), and predicted MTDH gene expression plays an important role in tumor invasion and metastasis; 7,14 in 23 cases MTDH gene-positive patients became negativ after adjuvant chemotherapy in 2 to 3 cycles, negative rate was 60.9%(14/23), indicating that chemotherapy can significantly reduce the level of gene expression.Conclusion:1 When MTDH gene detected in peripheral blood of patients with breast cancer, lung cancer and other solid tumors, it suggested that circulating tumor cells have came into the blood, then indicated that micrometastases may exist in the blood, so MTDH gene is expected to be a tumor marker determining early metastasis; 2, From relation research between MTDH gene quantitative expression in breast cancer patients in and clinical pathological characteristics of breast cancer, we found MTDH gene quantitative expression were positively correlated with lymph node metastasis and clinical stage, and was negatively correlated with the survival time of patients; 3, quantitative expression of MTDH gene in breast cancer patients was significantly changed before and after adjuvant chemotherapy, and found high expression of MTDH gene of breast cancer patients has poor prognosis and shorter survival. In conclusion, Expression level of MTDH gene in peripheral blood is closely related to poor prognostic factor and it maybe used as a predictive marker.