Study On Expression Of ALDH1in Primary Cancer And Lymph-node Metastasis Tumor Of Breast Cancer And Its Relationship With The Invasion And Metastasis

Background and objectiveBreast cancer is one of the most frequent malignant tumors of women, which has a strong impact on their physical and psychological health, and what is even more serious is that it can threaten their lives. At present, the pathogenesis of breast cancer has not elucidated completely. Several domestic and abroad studies suggest that its occurrence and development is a progressional process in which many factors participate. At present, breast cancer stem cell becomes a hot topic of research.lt may initiate the growth of breast cancer and it may be the root cause of its recurrence and far metastasis after neoadjuvant chemotherapy. As a result, exterminating the breast cancer stem cell thoroughly may cure breast cancer completely.Aldehyde dehydrogenase1(ALDH1) has been identified as a reliable marker of breast cancer stem cells. ALDH1belongs to a member of the aldehyde dehydrogenase family, wich is closely related to occurrence, development, prognosis and metastasis of breast cancer and highly expressed on the surface of breast cancer stem cells. ALDH1, a detoxifying enzyme responsible for the oxidation of intracellular aldehydes, was shown to play a role in the early differentiation of stem cells, through its role in oxidizing retinol to retinoic acid. Growing evidence suggests that cancer stem cells possess characteristic in terms of adhesion, migration and attack ability. Compared to differentiated offspring cells, cancer stem cells can overexpress a variety of invasion-related factors including CXCR4, CD44, MMP2and so on. It prompts that cancer stem cells maybe paly an important role in the invasion and metastasis of malignant tumor.MMPs family is a highly conserved family of endogenous proteolytic enzymes and is a major regulator of extracellular matrix material, which can degrade almost all components of the extracellular matrix. MMP-2is one of the main members of the family and plays an important role in the process of tumor’s invasion and metastasis, because it mainly acts on the basement membrane collagen type IV and promotes tumor cells break through the basement membrane barrier.CXC chemokine receptor4belongs to the G protein-coupled receptors superfamily and is one of CXC-chemokine receptors, which is the specific receptor of Stromal cell derived factor-1(SDF-1). The CXCR4-SDF-1biology axis maybe paly an important role in the migration, invasion, metastasis and proliferation of breast cancer.The researches about combined detection of ALDH1, MMP2, CXCR4expressions in both primary carcinomas and lymph node metastases of invasive ductal carcinoma and their relationship with breast cancer invasion and lymph node metastasis have not been reported. In addition, fewer studies have been used for the biological function of ALDHl,and the mechanism of action of ALDH1is also poorly understood.To investigate the expressions of breast cancer cells which are marked with ALDH1in primary carcinomas and lymph node metastases of breast cancer and their relationship with breast cancer invasion and metastasis and the possible mechanism, the present study detects the expressions of ALDH1,MMP2,CXCR4proteins by immunohistochemistry and ALDH1mRNA by in situ hybridization in90cases of primary carcinomas and60cases of lymph node metastases of invasive ductal carcinoma,and explore the relationship among ALDH1,MMP2,CXCR4and the probable mechanism.It is helpful for researchers to find out new ideas for the therapy of breast cancer invasion and metastasis.Methods1. Expressions of ALDH1, MMP2, CXCR4proteins were detected by immunohistochemical staining of SP method in90cases of primary carcinomas and60cases of lymph node metastases of invasive ductal carcinoma.2. Expression of ALDHlmRNA was detected by the technique of in situ hybridization in90cases of primary carcinomas and60cases of lymph node metastases of invasive ductal carcinoma.3. Statistical analysis:All the dates were analyzed by SPSS17.0statistical software package. The Chi-square was used for the comparison of positive rates; the Spearman’s correlation analysis was used for analyzing the correlation of two variables. The level of significant difference is a=0.05.Results1. The positive rates of ALDH1protein, ALDHl mRNA, MMP2protein and CXCR4protein were27.8%(25/90),30%(27/90),70.0%(63/90) and76.7%(69/90) respectively in90cases of primary carcinomas of invasive ductal carcinoma. The positive rates of ALDH1protein (mRNA) were28.3%(31.7%) and35%(35%) respectively in60cases of primary carcinomas and corresponding lymph node metastases of invasive ductal carcinoma, and the expressions in two parts were positively related to each other. And the expression characteristics of lymph node metastases that ALDH1protein and mRNA are both scattered or small cluster-like distribution were similar with the primary cancers.The positive rates of MMP2protein were81.7%and75.0%respectively in60cases of primary carcinomas and corresponding lymph node metastases of invasive ductal carcinoma, but there was no correlation in the two parts. The positive rates of CXCR4protein were85.0%and80.0%respectively in60cases of primary carcinomas and corresponding lymph node metastases of invasive ductal carcinoma, but there was also no correlation in the two parts.2. In90cases of primary carcinomas of invasive ductal carcinoma, the expressions of ALDH1protein and mRNA were both positive correlated with high histological grade, ER negativity, PR negativity(P<0.05); the expressions of MMP2protein and CXCR4protein were both positive correlated with high histological grade and lymph node metastasis(P<0.05). In60cases of lymph node metastases of invasive ductal carcinoma, the expressions of ALDH1protein and mRNA were both positive correlated with ER negativity, PR negativity(P<0.05); the expressions of MMP2protein and CXCR4protein were both not correlated with any clinicopathological parameter(P>0.05).3. In90cases of primary carcinomas of invasive ductal carcinoma, there was a positive correlation between the expression of ALDH1protein and MMP-2protein (r=0.298, P<0.05); there was a positive correlation between the expression ofALDHlprotein and CXCR4protein (r=0.283, P<0.05); there was a positive correlation between the expression of MMP-2protein and CXCR4protein (r=0.556, P<0.05); moreover, the positive rates of MMP-2protein and CXCR4protein in ALDH1-positive group were significantly higher than that in ALDH1-negative group, and the difference was statistically significant (P<0.05). In60cases of lymph node metastases of invasive ductal carcinoma, there was a positive correlation between the expression ofALDHl protein and MMP-2protein (r=0.343, P<0.05); there was a positive correlation between the expression ofALDHl protein and CXCR4protein (r=0.280, P<0.05); there was a positive correlation between the expression of MMP-2protein and CXCR4protein (r=0.481, P<0.05); moreover, the positive rates of MMP-2protein and CXCR4protein in ALDH1-positive group were significantly higher than that in ALDH1-negative group, and the difference was statistically significant (P<0.05).4. In90cases of primary carcinomas of invasive ductal carcinoma, ALDH1and MMP2proteins were both positive expressions in23cases of carcinoma tissues,20cases(87.0%) of which were found ALDH1-positive cells expressed MMP2protein at the same time; ALDH1and CXCR4proteins were both positive expressions in24 cases of carcinoma tissues,23cases(95.8%) of which were found ALDH1-positive cells expressed CXCR4protein at the same time.In60cases of lymph node metastases, ALDH1and MMP2proteins were both positive expressions in20cases of carcinoma tissues,18cases(90.0%) of which were found ALDH1-positive cells expressed MMP2protein at the same time; ALDH1and CXCR4proteins were both positive expressions in20cases of carcinoma tissues,19cases(95%) of which were found ALDH1-positive cells expressed CXCR4protein at the same time.Conclusions1. ALDHl protein and mRNA were expressed both in primary carcinomas and lymph node metastases, and were mainly expressed in the ER negative、PR negative、 poorly differentiated cancer tissue.2. In breast infiltrative ductal carcinoma tissues, ALDH1-positive expression may play an important role in promoting invasion and metastasis of breast cancer, and the mechanism may be related to expressions of MMP-2and CXCR4of ALDH1-positive breast cancer cells.