No abstract

Interaction between cell surface integrin receptors with extracellular matrix (ECM) plays an important role in cell survival, proliferation, and migration including tumor development and invasion. Binding of ECM to integrins initiates intracellular signaling cascades, modulating expression and activity of different matrix metalloproteinases (MMPs) which is important in ECM degradation. The present study investigates fibronectin-integrin-mediated signaling and thereby modulation of MMPs expression and activity in human breast cancer cell line, MDA-MB-231. Culture of MDA-MB-231 cells on fibronectin (FN) induced expression and activity of pro-matrixmetalloproteinase-9 (MMP-9). Appreciable reduction of FN-induced pro-MMP-9 activity was observed in anti-α5 antibody treated cells. Inhibitor studies revealed that inhibitors of phosphatidyl inositiol-3-kinase (PI-3K), and nuclear factor kappa B (NF-κB) inhibited FN-induced pro-MMP-9 activity. FN increased tyrosine phosphorylation of focal adhesion kinase (FAK), integrin linked kinase (ILK), and PI-3K in MDA-MB-231 cells. FN-induced the transactivation of MMP-9 promoter by enhancing DNA binding activity of NF-κB and Sp1. Wound healing assay showed faster migration of MDA-MB-231cells grown on fibronectin-coated as surface as compared to control. Our findings indicated that culture of MDA-MB-231 on fibronectin perhaps send signals via fibronectin-integrin-mediated signaling pathways recruiting FAK, PI-3K, ILK, NF-κB, and modulate expression and activation of pro-MMP-9. These observations may enrich fundamental aspects of cancer biology especially role of α5β1 integrin in regulation of MMPs expression and activity.

The tumor-inhibiting property of black tea polyphenol, theaflavin, is well documented. Matrix metalloproteinases (MMPs) play a pivotal role in tumor invasion through degradation of extracellular matrix (ECM). In the present study, we observed the effect of theaflavin on MMP-2, which is upregulated in most tumor types, and its regulatory molecules, in human melanoma cell line, A375. The treatment of theaflavin downregulated the gelatinolytic activity, mRNA and protein expression of MMP-2. It reduced the mRNA and protein expression of membrane type-1 MMP (MT1-MMP) and induced mRNA and protein expression of tissue inhibitor of MMP-2 (TIMP-2), suggesting theaflavin's inhibitory effect on MMP-2 activation. Theaflavin reduced the binding of A375 cell to ECM ligands demonstrating that theaflavin treatment hinders cell-ECM adhesion, cell motility, and integrin-mediated MMP-2 activation. Theaflavin treatment inhibited the protein expression FAK EGFR and ERK, suggesting that, theaflavin treatment downregulates the molecules participating in MMP-2 secretion and regulation. The downregulation of NFchiB suggests downregulation of MMP-2 transactivation. Theaflavin also reduced the tumor volume in syngenic black mice. Thus, we report that theaflavin causes an inhibition of the expression and activity of pro-MMP-2 by a process involving multiple regulatory molecules in human melanoma cells, A375.

This study aimed to detect the comparative expression and activity of matrix metalloproteinase-9 (MMP-9) and its correlation with known pathological parameters such as estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) in 81 malignant breast tumors and adjacent normal breast tissues and in blood sera of these patients from different clinical TNM stages (ductal carcinoma in situ to T4) of breast cancer. MMP-9 was highly expressed in node-positive tumors and the preoperative blood serum of patients, but MMP-9 activity was appreciably inhibited in blood serum samples collected after surgery. The mature form of MMP-9 (84 kD) was expressed only in clinical stage III tumors (T2-4). Appreciable reduction of tissue inhibitor of metalloproteinase 1, phosphorylation of epidermal growth factor receptor, and translocation of nuclear factor-κΒ suggested their possible role in MMP-9 activation in HER2-positive breast cancer Overexpression and activation of MMP-9 predicted a higher stage of hormone-sensitive ductal breast carcinoma. Downregulation of the endogenous inhibitor of MMP-9, tissue inhibitor of metalloproteinase 1, and translocation of the transcription factor nuclear factor-κΒ in tumors may have an appreciable role in the overexpression of MMP-9. However, MMP-9 activation was not correlated with expression of estrogen and progesterone receptors. Evaluation of MMP-9 expression may provide valuable information about breast cancer treatment.

The present study aimed to detect comparative expression of integrin α V β 3 and its involvement in expression and activation of matrix metalloproteinase-2 (MMP-2) in 25 malignant human breast tumor and adjacent normal breast tissues from different clinical TNM stages (DCIS to T4) of the disease and possible involvement of known regulating parameters of MMP-2 like TIMP-2, MT1-MMP and EMPRIN. Integrin α V β 3 was highly expressed in tumors than adjacent normal breast tissues. Pro-MMP-2(72-KD) was mainly expressed in adjacent normal tissues compared to tumors. The mature forms of MMP-2 (68 KD and 64 KD) were found only in tumors. Appreciable expression of TIMP-2 and induction of MT1-MMP and EMPRIN in T2-T4 stages suggested their possible role in MMP-2 activation. Over expression Integrin αVβ3 in tumors than adjacent normal breast tissues was an indication of cancer progression with involvement of integrin signaling. We conclude that, the co-precipitation of MMP-2 with αvβ3 by anti-α v antibody is a strong indication that integrin α v β 3 is a surface receptor for MMP-2 and α v β 3-MMP-2 complex on the surface of tumor cells may play a very important role in determining the invasive property and malignant behavior of tumor tissues. The positive expression of endogenous inhibitor of MMP-2, TIMP-2 may have an appreciable role in activation of this protease and risk of malignancy in advanced stage of the disease. The enhanced expression of MT1-MMP and EMPRIN suggested a role for these factors in gelatinase regulation. However the exact mechanism(s) remains to be investigated. Finally, evaluation of integrin αVβ3 associated MMP-2 expression and activity may add valuable information and can possibly be therapeutic target. The clinical exploitation of integrins will provide oncologists with novel therapeutic strategies for the treatment of malignancy in breast cancer.