Objective: To further study the anti-metastasis mechanism of laminin-glycopeptides on carcinoma cell proliferation, apoptosis and the secretion of matrix metalloproteinases.
Methods: Human hepatocellular carcinoma cells in serum free medium were incubated on laminin-coated substrate with or without laminin-glycopeptides at a final concentration of 50 micrograms/ml. The total number of surviving cells after incubating for the indicated time was assayed by MTT assay. DNA synthesis of the incubated cells was detected by 3H-TdR incorporation. Cell cycle was analysed by FACS. The mitotic index of Giemsa stained cells was assessed. Cell apoptosis was detected by both FACS and an acridine orange staining method. Matrix metalloproteinase secretion was analysed by gelatin zymography.
Results: The total number of surviving cells incubated on laminin in the absence of laminin-glycopeptides was significantly larger than that in the presence of laminin-glycopeptides. Laminin promoted 3H-TdR incorporation of carcinoma cells, decreased the percentage of cells in G1 phase and increased the percentage of cells in S phase. In contrast, laminin-glycopeptides could inhibit the effect of laminin as shown by 3H-TdR incorporation and cell cycle analysis. The percentage of cells in G2 + M phase and the mitotic index among various groups showed no significant difference. Matrix metalloproteinases secretion from cells treated by laminin-glycopeptides was much less compared to that without the treatment by laminin-glycopeptides.
Conclusion: Laminin may stimulate cell proliferation, while laminin-glycopeptides could significantly inhibit the effect of laminin by inhibiting DNA synthesis and arresting the carcinoma cell cycle from G1 to S phase. These effects may inhibit not only tumor growth of the primary carcinoma, but also the establishment of metastases at ectopic tissues. Laminin-glycopeptides could also inhibit the secretion of matrix metalloproteinases from carcinoma cells and this may contribute to their decreased invasive and metastatic phenotype. This study further revealed the cellular and molecular mechanism of laminin-glycopeptides on anti-metastasis.