The Study On The Deletion Of Exons And Protein Expression Of Rap1GAP, And Its Relationship With The Expression Of MMP2 And MMP9 In Invasive Breast Cancer

Objective: To explore the deletion of Rap1GAP exons of E11 and E19, protein expression of Rap1GAP, MMP2, MMP9 in invasive breast cancer, and the correlation of these indicators in invasive breast cancer for understanding the molecular mechanisms of breast cancer.Breast cancer, a malignant tumor of breast ductal epithelial cells, is a common malignancy of women. In the world, there are about one million women are diagnosed with breast cancer each year, and breast cancer incidence increase by 5% -20% per year. In China, the incidence of breast cancer ranked second only to cervical cancer. The occurrence and progression of tumor is a multi-factors, multi-stages process and is based on a variety of proto-oncogene activation and tumor suppressor gene inactivation. Rap1GAP is a tumor suppressor gene and is closely related with the occurrence and progression of a variety of tumors.Rap1GAP( Rap1 GTPase-activating protein 1) is a Rap1-specific GTP- activating protein, regulating the activity of Rap1 from the GTP binding active form to the GDP binding inactive form. It regulates cell biological functions such as growth, productivity, adhesion and so on. Our group's Preliminary studies have shown that: Rap1GAP inhibited Hela cells proliferation, migration and invasion; And Rap1GAP inhibited Hela cells migration and invasion by inhibiting the activities of MMP2 and MMP9. Cervical cancer and breast cancer are two major killers of female diseases, a variety of genes changes are same in both cancer tissues. In this paper, we studied the deletion of Rap1GAP exons of E11 and E19,protein expression of Rap1GAP, MMP2, MMP9 in invasive breast cancer, and analyzed the correlation of these indicators in invasive breast cancer.Methods: 53 cases surgical breast tissue specimens were from Dalian Central Hospital Pathological Centers, including 10 cases of normal breast tissues, 17 cases of breast lobular hyperplasia tissues and 26 cases of invasive ductal carcinoma. All specimens were diagnosed by pathology. DNA was extracted form pathohistological sections, PCR method used to check the homozygous deletion of Rap1GAP exon E11 and exon E19. Extraction DNA, PCR method used to measure the homozygous deletion of Rap1GAP exon E11, exon E19. The expression of Rap1GAP, MMP2, MMP9 in breast tissue slices were investigated by S-P method of immuno- histochemistry. the correlation of these indicators in breast lobular hyperplasia tissues and invasive ductal carcinoma were analyzed.Results:1. The deletion rates of Rap1GAP exon E11 homozygous were: 10 % (1/10), 11.76 % (2/17), 19.23 % (5/26) in normal breast tissues, breast lobular hyperplasia tissues and invasive ductal carcinoma tissues respectively. The deletion rates of Rap1GAP exon E19 homozygousthe were: 20 % (2/10), 11.76 % (2/17), 19.23 % (5/26) in normal breast tissues, breast lobular hyperplasia tissues and invasive ductal carcinoma tissues respectively. There were no significantly difference in deletion rates of exon E11 and E19 among the three groups (p>0.05).2. The expression rates of Rap1GAP were: 80 % (8/10), 52.94 % (9/17), 30.77% (8/26) in normal breast tissues, breast lobular hyperplasia tissues and invasive ductal carcinoma tissues respectively. Rap1GAP expression was lower in invasive ductal carcinoma tissues than that in breast lobular hyperplasia tissues (p<0.05) and in normal tissue (p<0.05). Rap1GAP expression was lower in breast lobular hyperplasia tissues than that in normal breast tissues (p<0.05).3. The expression rates of MMP2 were: 20 % (2/10), 23.53 % (4/17), 53.85% (14/26) in normal breast tissues, breast lobular hyperplasia tissues and invasive ductal carcinoma tissues respectively. Among the three types of breast tissues, MMP2 expression was higher in invasive ductal carcinoma tissues than that in breast lobular hyperplasia tissues (p<0.05) and in normal breast tissues (p<0.05). there was no difference between the breast lobular hyperplasia tissues and normal breast tissues (p>0.05)4. The expression rates of MMP9 were: 10 % (1/10), 23.53 % (4/17), 57.69% (14/26) in normal breast tissues, breast lobular hyperplasia tissues and invasive ductal carcinoma tissues respectively. among the three types of breast tissues, MMP9 expression was higher in invasive ductal carcinoma tissues than that in breast lobular hyperplasia tissues (p<0.05) and in normal breast tissues (p<0.05), and it was higher in breast lobular hyperplasia tissues than that in normal breast tissues (p<0.05).5. Spearman correlation analysis:5.1 No significant correlation were observed between Rap1GAP expression and exon E11, E19 deletion (p>0.05).5.2 There was negative correlation between the positive rate of Rap1GAP and MMP2 expression in breast lobular hyperplasia tissues (p<0.05) and invasive ductal carcinoma tissues (p<0.05). Significant negative correlation were observed between the positive rate of Rap1GAP and MMP9 expression in breast lobular hyperplasia tissues (p<0.05) and invasive ductal carcinoma tissues (p<0.05). But there was no correlation between the positive rate of MMP2 and MMP9 expression in breast lobular hyperplasia tissues (p>0.05)and invasive ductal carcinoma tissues (p>0.05).Conclusions:1. The deletion rates of Rap1GAP exon E11 and E19 have no correlation in invasive ductal carcinoma tissues, breast lobular hyperplasia tissues and invasive ductal breast cancer.2. The expression rates of Rap1GAP protein in invasive ductal carcinoma were lower than that in breast lobular hyperplasia and in normal breast tissue. Its expression in breast lobular hyperplasia was lower than that in normal breast tissues.3. The expression rates of MMP2, MMP9 protein was higher in invasive ductal carcinoma than that in the breast lobular hyperplasia and in normal breast tissue. Its expression in breast lobular hyperplasia is higher than that in normal tissue.4. In the breast lobular hyperplasia and invasive ductal carcinoma tissue, the expression of Rap1GAP was down-regulation, but the expression of MMP2, MMP9 was up-regulation and negative correlation were observed between Rap1GAP expression and MMP2/MMP9.5. The major cause of down-regulation of Rap1GAP may not relay on gene deletion.