8-chloroadenosine 3',5'-monophosphate (8-Cl-cAMP) selectively eliminates protein kinase A type I to induce growth inhibition in c-ras-transformed fibroblasts.
8-Chloroadenosine 3',5'-monophosphate (8-Cl-cAMP), a site-selective cyclic adenosine 3',5'-monophosphate (cAMP) analogue, exhibits growth inhibition in a broad spectrum of cancer cell lines. We investigated the effect of 8-Cl-cAMP on c-ras-transformed mouse fibroblasts (MP3/3T3) which were established by transfection of Balb3T3 cells (Balb3T3) with the point-mutated c-ras gene [G12-->V12]. 8-Cl-cAMP (2-5 microM) exerted over 80% growth inhibition by day 4 on MP3/3T3, while inhibiting parental Balb3T3 cell growth less than 40%. In order to distinguish the effect of 8-Cl-cAMP from that of 8-chloroadenosine (8-Cl-adenosine), we examined the effect of 8-Cl-cAMP in serum-free medium. 8-Cl-cAMP demonstrated a potent growth inhibition of MP3/3T3 cells cultured in serum-free medium, suggesting that the growth inhibitory effect of 8-Cl-cAMP was not due to its hydrolysed product, 8-Cl-adenosine. In addition, both Balb3T3 and MP3/3T3 contained cAMP phosphodiesterases mainly composed of isozyme IV which has previously been reported to be insensitive towards the hydrolysis of 8-Cl-cAMP. Non-transformed Balb3T3 cells contained only type II cAMP-dependent protein kinase (PKA), whereas transformed MP3/3T3 exhibited a marked increase in type I PKA. The growth inhibition of MP3/3T3 by 8-Cl-cAMP accompanied almost complete elimination of type I PKA without affecting type II PKA. Moreover, 8-Cl-cAMP induced an arrest in the G0/G1-phase of the cell cycle in MP3/3T3. 8-Cl-adenosine had little or no effect on the cell cycle kinetics of MP3/3T3 cells. These results show that 8-Cl-cAMP is a novel cAMP analogue which selectively eliminates type I PKA to induce growth inhibition in transformed fibroblasts.
Noguchi
K
K
Cellular Biochemistry Section, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-1750, USA.
Murata
T
T
Cho-Chung
Y S
YS
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D011905:Genes, ras; D051379:Mice; D015689:Oncogene Protein p21(ras) / Q000494:pharmacology*
D000970:Antineoplastic Agents; D015124:8-Bromo Cyclic Adenosine Monophosphate; C044258:8-chloro-cyclic adenosine monophosphate; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D015689:Oncogene Protein p21(ras)