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[Cancer Research 35, 82-87, January 1, 1975]
© 1975 American Association for Cancer Research
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Cyclic Adenosine 3':5'-Monophosphate Phosphodiesterase Activity in Malignant and Cyclic Adenosine 3':5'-Monophosphate-induced "Differentiated" Neuroblastoma Cells1

S. Kumar, G. Becker and K. N. Prasad

Department of Radiology, University of Colorado Medical Center, Denver, Colorado 80220

The regulation of cyclic adenosine 3':5'-monophosphate (cyclic AMP) phosphodiesterase activity in homogenates of malignant and cyclic AMP-induced "differentiated" neuroblastoma cells was studied. Neuroblastoma cells of at least three mouse and one human clone had both the low (2 to 4 µM) and the high (66 to 106 µM) Km phosphodiesterase. In cyclic AMP-induced differentiated cells the values of Km were slightly decreased, whereas the values of Vmax appeared to be slightly increased. Magnesium and manganese stimulated phosphodiesterase activity. Calcium, zinc, copper, mercury, ethylenediaminetetraacetic acid, and imidazole completely inhibited phosphodiesterase activity in malignant cells, whereas the above agents, except ethylenediaminetetraacetic acid, only partially inhibited enzyme activity in differentiated cells. Ethylenediaminetetraacetic acid completely reduced phosphodiesterase activity in differentiated cells. The pH optimum for phosphodiesterase activity was about 8 in both malignant and differentiated cells. The present studies show that the values of Km and Vmax and the sensitivity of phosphodiesterase activity to divalent ions change in cyclic AMP-induced differentiated neuroblastoma cells, and therefore we propose that the reverse may be true during malignant transformation of nerve cells.

1 This work was supported by USPHS Grants NSO9230 and CA 12247.

Received 7/22/74. Accepted 10/ 1/74.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Cancer Research Clinical Cancer Research
Cancer Epidemiology Biomarkers & Prevention Molecular Cancer Therapeutics
Molecular Cancer Research Cancer Prevention Research
Cancer Prevention Journals Portal Cancer Reviews Online
Annual Meeting Education Book Meeting Abstracts Online
Copyright © 1975 by the American Association for Cancer Research.