| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
The present study was conducted to clarify the mechanism that determines the mode of invasion of human oral squamous cell carcinomas. Three cell lines derived from human oral squamous cell carcinomas with different modes of invasion were assayed for their ability to migrate or invade in vitro. The cell lines employed were HOC3 13, OSO 19 and OSC2O cells, which respectively derive from oral tumors of the highest (grade 4D), high (grade 40) and moderate (grade 3) invasiveness, A phagokinesis assay with gold particles demonstrated that, among the three cell lines, the rate of migration in serum-containing media was ranked in the following order : H0C313 * OSCI9 > OSC2O.In serum free media, H0C313 cells also exhibited a high motility rate, whereas OSCl9 and OSC2O cells migrated to much lesser extents, suggesting that the HOC313 cells produce motility factors that act on themselves in an autocrine manner. Next, the nature of this activity was investigated. Northern blot analysis revealed th
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at the gene coding for autocrine motility factor (AMF) was extremely strongly expressed in HOC313 cells ; two prominent hybridizing bands were detected at 2.0 and 4.0 kb. On the other hand, OSC19 cells expressed the 2.0 kb mRNA species at a low level, and OSC19 cells had barely detectable amounts of AMF mRNA.AMF proteins were clearly marked by immunohistochemical staining with anti-AMF antibodies in H0C313 cells, but not in OSC19 and OSC2O cells ; the immunoreactivity was localized in pseudopodia in a granular pattern. mRNA encoding AMF receptor was detected at a high level in H0C313 and OSC20 cells, and at a low level in OSCl9 cells. In Western blotting, AMF receptor proteins (gp78) were detected at a high level in H0C313 cells, at a low level in OSC2O cells, and not at all in OSCl9 cells. Relative amounts of the AMF and AMF receptor proteins in three cell lines were well correlated with their motility rates. The migration of HOC313 cells in serum-free media was markedly blocked by anti-AMF antibodies. Further, exogenously added glucose 6-phosphate isomerase, which is known to have the same amino acid sequence as AMF, stimulated HOC313 cell motility in a dose-dependent manner. These results indicate that AMF would at least partly account for the high motility of HOC313 cells, and this is the first demonstration that squamous carcinoma cells produce an autocrine factor that induces their own motility. The present study also established the effects of hepatocyte growth factor (HGF)/scatter factor (SF) and cxtracellular matrix components such as fibronectin and vitronectin on the chemotaxis of the oral squamous carcinoma cells. HGF/SF stimulated in a dose dependent manner the H0C313 cell migration through 8 mum pore sized filter to the highest extent. OSC2O cells exhibited a moderate migration toward HGF/SF, while OSCl9 cells did not respond to it. Fibronectin and vitronectin were also found to stimulate the migration of H0C313 cells. The migration of OSC19 cells was Less
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