Noguchi K, Murata T, Cho-Chung YS. 8-chloroadenosine 3',5'-monophosphate (8-Cl-cAMP) selectively eliminates protein kinase A type I to induce growth inhibition in c-ras-transformed fibroblasts.
Eur J Cancer 1998;
34:1260-7. [PMID:
9849489 DOI:
10.1016/s0959-8049(98)00051-3]
[Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
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.
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