Role of beta1-Integrin in Colorectal Cancer: Case-Control Study

PURPOSE: In the metastatic process, interactions between circulating tumor cells (CTCs) and the extracellular matrix or surrounding cells are required. beta1-Integrin may mediate these interactions. The aim of this study was to investigate whether beta1-integrin is associated with the detection of CTCs in colorectal cancer. METHODS: We enrolled 30 patients with colorectal cancer (experimental group) and 30 patients with benign diseases (control group). Blood samples were obtained from each group, carcinoembryonic antigen (CEA) mRNA for CTCs marker and beta1-integrin mRNA levels were estimated by using reverse transcription-polymerase chain reaction, and the results were compared between the two groups. In the experimental group, preoperative results were compared with postoperative results for each marker. In addition, we analyzed the correlation between the expressions of beta1-integrin and CEA. RESULTS: CEA mRNA was detected more frequently in colorectal cancer patients than in control patients (P = 0.008). CEA mRNA was significantly reduced after surgery in the colorectal cancer patients (P = 0.032). beta1-Integrin mRNA was detected more in colorectal cancer patients than in the patients with benign diseases (P < 0.001). In colorectal cancer patients, expression of beta1-integrin mRNA was detected more for advanced-stage cancer than for early-stage cancer (P = 0.033) and was significantly decreased after surgery (P < 0.001). In addition, expression of beta1-integrin mRNA was significantly associated with that of CEA mRNA in colorectal cancer patients (P = 0.001). CONCLUSION: In conclusion, beta1-integrin is a potential factor for forming a prognosis following surgical resection in colorectal cancer patients. beta1-Integrin may be a candidate for use as a marker for early detection of micrometastatic tumor cells and for monitoring the therapeutic response in colorectal cancer patients.

beta1-integrin-dependent migration of microglia in response to neuron-released alpha-synuclein

Chronic neuroinflammation is an integral pathological feature of major neurodegenerative diseases. The recruitment of microglia to affected brain regions and the activation of these cells are the major events leading to disease-associated neuroinflammation. In a previous study, we showed that neuron-released alpha-synuclein can activate microglia through activating the Toll-like receptor 2 (TLR2) pathway, resulting in proinflammatory responses. However, it is not clear whether other signaling pathways are involved in the migration and activation of microglia in response to neuron-released alpha-synuclein. In the current study, we demonstrated that TLR2 activation is not sufficient for all of the changes manifested by microglia in response to neuron-released alpha-synuclein. Specifically, the migration of and morphological changes in microglia, triggered by neuron-released alpha-synuclein, did not require the activation of TLR2, whereas increased proliferation and production of cytokines were strictly under the control of TLR2. Construction of a hypothetical signaling network using computational tools and experimental validation with various peptide inhibitors showed that beta1-integrin was necessary for both the morphological changes and the migration. However, neither proliferation nor cytokine production by microglia was dependent on the activation of beta1-integrin. These results suggest that beta1-integrin signaling is specifically responsible for the recruitment of microglia to the disease-affected brain regions, where neurons most likely release relatively high levels of alpha-synuclein.

CD98 Activation Increases the Invasion of Human Breast Carcinoma MCF-7 Cells / 체질인류학회지

CD98, a disulfide-linked 125-kDa heterodimeric type II transmembrane glycoprotein, regulates the func-tions of beta1 integrin, suggesting that it may play a role in tumor cell invasion. In this study, the effects of CD98 signaling on the adhesion and invasion of tumor cells were investigated. The expression of CD98 on MCF-7 human breast carcinoma cells was confirmed by immunohistochemistry. The effects of CD98 activation on the adhesion to extracellular matrix (ECM) and invasion of MCF-7 cells were determined by adhesion assay and cell invasion assay. Dominant negative forms of focal adhesion kinase (FAK) were transiently transfected into MCF-7 cells using liposome reagents. CD98 stimulation increased the adhesion of MCF-7 cells to fibronectin, laminin and collagen IV. Activation of CD98 augmented the invasion rate of MCF-7 cells through ECM. EDTA or a function-blocking anti-beta1 integrin mAb suppressed the effect of CD98 on invasiveness. Inhibition of phosphorylation of FAK by PP2, an inhibitor of Src family kinase, reduced CD98-induced invasion of MCF-7 cells. This result was confirmed by over-expression of dominant negative forms of FAK. In addition, cytochalasin D or phalloidin inhibited CD98-mediated induction of tumor cell invasion. Inhibitory effects of PP2, cytochalasin D or phalloidin on CD98-stimulated invasion of MCF-7 cells were diminished by pretreatment of cells with Mn++, which is shown to induce conformational change of beta1 intgerin. These results provide the first evidence that CD98 activation increases tumor cell invasion by activating beta1 integrin affinity, and that FAK phosphorylation and subsequent cytoskeletal reorganization may be essential for CD98-mediated regulation of cell motility.

Beta ig-h3 promotes renal proximal tubular epithelial cell adhesion, migration and proliferation through the interaction with alpha3beta1 integrin

Betaig-h3 (betaig-h3) is a secretory protein composed of fasciclin I-like repeats containing sequences that allows binding of integrins and glycosaminoglycans in vivo. Expression of betaig-h3 is responsive to TGF-beta and the protein is found to be associated with extracellular matrix (ECM) molecules, implicating betaig-h3 as an ECM adhesive protein of developmental processes. We previously observed predominant expression of betaig-h3 expression in the basement membrane of proximal tubules of kidney. In this study, the physiological relevance of such localized expression of betaig-h3 was examined in the renal proximal tubular epithelial cells (RPTEC). RPTEC constitutively expressed betaig-h3 and the expression was dramatically induced by exogenous TGF-beta1 treatment. betaig-h3 and its second and fourth FAS1 domain were able to mediate RPTEC adhesion, spreading and migration. Two known alpha3beta1 integrin-interaction motifs including aspartatic acid and isoleucine residues, NKDIL and EPDIM in betaig-h3 were responsible to mediate RPTEC adhesion, spreading, and migration. By using specific antibodies against integrins, we confirmed that alpha3beta1 integrin mediates the adhesion and migration of RPTECs on betaig-h3. In addition, it also enhanced proliferation of RPTECs through NKDIL and EPDIM. These results indicate that betaig-h3 mediates adhesion, spreading, migration and proliferation of RPTECs through the interaction with alpha3beta1 integrin and is intimately involved in the maintenance and the regeneration of renal proximal tubular epithelium.

Expression of alpha3beta1 Integrin in ECV304 Endothelial Cells and Angiogenesis / 대한해부학회지

Angiogenesis is a fundamental biological process including endothelial cell adhesion, migration, invasion and tube formation. Integrin receptors of endothelial cells play important roles in angiogenesis. They mediate cell-cell contact and cell adhesion to extracellular matrix. Roles of integrins have been described for a number of cell types. ECV304 endothelial cells were known to overexpress alpha3beta1 integrin and to form tube like structure in 3-D Matrigel culture. However the function of alpha3beta1 integrin in endothelial cells remains to be determined. Therefore, we have investigated morphological characteristics of ECV304 cells and roles of alpha3beta1 integrin in angiogenesis. To elucidate several characteristics, ECV304 endothelial cells were compared with HUVEC in the aspect of morphology, localization of integrins, angiogenesis pattern. In addition, role of alpha3beta1 integrin were analyzed in the aspect of endothelial cell binding, migration, invasion and tube formation on Matrigel. The result showed that alpha3beta1 integrin overexpressed ECV304 endothelial cells showed strong adhesiveness to extracellular matrix proteins, and high migration and invasion activities. Furthermore, expression of alpha3beta1 integrin was increased according to time course during in vitro culture and was continuously strong in ECV304 cells on 3-D Matrigel culture. These results indicate that alpha3beta1 integrin is able to be a critical component in control of angiogenesis by regulation of cell adhesion, migration, invasion and tube formation of ECV304 endothelial cells.

Effects of Mixed Leukocyte Reaction, Hydrocortisone, or Cyclosporine A on Expression of Adhesion Molecules by Endothelial and Mesangial cells / 대한내과학회지

OBJECTIVES: ICAM-1, VCAM-1, and betal integrins mediate cell-cell or cell-matrix interactions. We investigated effects of mixed leukocyte reaction (MLR), cyclosporine A (CsA), or hydrocortisone (HC) on their expression by endothelial (EnC) and mesangial cells (MC). METHODS: MLR was performed with or without CsA or HC for 5 days. After adding 25N MLR supernatant, cytokines or CsA to MC or EnC, the expression of VCAM-1, ICAM-1, and alpha3beta1 and a501 integrins was examined by using cell surface enzyme immunoassays or flow cytometry. RESULTS: MLR supernatant induced a marked increase in the expression of ICAM-1 and VCAM-1 on MC or EnC(p<0.001). HC treatment during MLR effectively inhibited MLR-induced upregulation of VCAM-1 and ICAM-1 on both cells (p<0.005). HC had, however, no inhibitory effect on VCAM-1 expression when added with MLR supernatant to cells. CsA treatment during MLR caused a modest decrease in MLR-induced expression of VCAM-1 on EnC, but had no effect on that of ICAM-1. INFgamma or TGFbeta1 stimulated expression of VCAM-1, and INFgamma, IL-1beta, or TNF alpha expression of ICAM-1 on MC after 24 hr. INFgamma, or TGFbeta1 enhanced expression of alpha3beta1 or alpha5beta1 integrins on MC after 5 days. CsA caused a modest decrease in basal expression of VCAM-1, and also decreased the basal, or INFgamma, or TGFbeta1-induced expression of alpha3beta1 and alpha5beta1 integrins on MC. CONCLUSION: Alloreactive lymphocytes and monocytes upregulate expression of VCAM-1 and ICAM-1 on EnC and MC maybe by secretion of cytokines such as INFgamma, and facilitate leukocytes attachment and following renal or vascular injury. HC effectively prevent the upregulation of VCAM-1 and ICAM-1 by inhibiting the release of cytokines during MLR. CsA did not cause an increase in the expression of VCAM-1 and beta1 integrin.