| Budget Amount *help |
¥4,060,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥360,000)
Fiscal Year 2007: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Laminins are a diverse group of alpha/beta/gamma heterotrimers formed from five alpha, three beta and three gamma chains ; they are major components of all basal laminae (BLs). One laminin chain that has garnered particular interest due to its widespread expression pattern and importance during development is laminin alpha5. Little is known, however, about the expression and function of laminins containing the alpha5 chain in human hepatocellular carcinoma (HCC). Here, using a specific antibody, we examined the expression of laminin alpha5 in normal liver and in HCCs. In normal liver, although laminin alpha5 was observed in hepatic BLs underlying blood vessels and bile ducts, it was absent from the parenchyma, which may be the origin of HCC. On the other hand, laminin alpha5 deposition was observed throughout all HCCs tested, regardless of tumor grade. In well differentiated HCCs, it localized along the trabecules of the tumor. In poorly-differentiated HCCs, it was present in surrounding tumor nodules. In HCC cell lines, laminin alpha5 heterotrimerized with beta and gamma chains and was secreted into the culture media. To attempt to understand the function of laminins containing alpha5, the expression of its receptors in HCCs was also determined. In this regard, alpha3betal/alpha6betal integrins and Lutheran/basal cell adhesion molecule (Lu/B-CAM) were expressed in HCC cells. In vitro studies showed that HCC cells readily attached to laminin containing the alpha5 chain, more so than did primary hepatocytes. In addition to alpha3betal/alpha6betal integrins and Lu/B-CAM, laminin alpha5 was recognized by integrin alphalbetal, which also was expressed in HCC cells. These results suggest that laminins containing alpha5 serve as functional substrates regulating progression of HCC.
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