Increased activity of dipeptidyl peptidase IV in serum of hepatoma-bearing rats coincides with the loss of the enzyme from the hepatoma plasma membrane
- 10 Downloads
The specific activity of dipeptidyl peptidase IV (DPPIV E.C. 3.4.14.-) in the plasma membrane of Morris hepatoma 9121 or hepatoma 7777 was 3.5% and 2.9%, respectively, of that in the plasma membrane of rat liver. The enzyme activity in the serum of hepatoma-bearing rats was 141% (hepatoma 91219) and 162% (hepatoma 7777) of the normal value. cytochemical investigation showed that the DPP IV activity was almost completely absent from the hepatoma cell plasma membrane and was not sequestered within these cells. Indirect immunofluorescence staining with a polyclonal antibody directed against DPP IV indicated that the loss of activity was due to the absence of DPP IV molecules in the plasma membrane. The possibility that the enzyme is transferred from the membrane into the serum as a result of structural alterations is discussed.
Key wordsDipeptidyl peptidase IV hepatoma rats cancer markers immunofluorescence cytochemistry
Unable to display preview. Download preview PDF.
- 1.Kenny, A.J., Booth, A.G., George, S.G., Ingram, J., Kershaw, D., Wood, D.J., and Young, A.R., Biochem. J.155 (1976) 169.Google Scholar
- 3.Hixson, D.C., DeLourdes Ponce, M., Allison, J.P. and Walborg, E.F., Expl. Cell Res.152 (1984) 402.Google Scholar
- 7.Hino, M., Nagatsu, T., Kakumu, S., Okuyama, S., Yoshii, T., and Nagatsu, I., Clinica chim. Acta62 (1975) 5.Google Scholar
- 9.Fujita, K., Hirano, M., Tokunaga, K., Nagatsu, I., Nagatsu, T., and Sakakibara, S., Clinica chim. Acta81 (1977) 215.Google Scholar
- 10.Kojima, J., Kanatani, M., Kato, M., Tojah, F., and Nakamura, N., Clinica chim. Acta93 (1979) 181.Google Scholar
- 17.Lojda, Z., Gossrau, R., and Schiebler, T.H. Enzyme Histochemistry. A Laboratory Manual. Springer Verlag, Berlin 1979.Google Scholar
- 21.Park, C.-S., Dissertation. Technische Universität, Berlin 1985.Google Scholar