Inhibitors of RNA synthesis and passage of chick embryo fibroblasts through the G1 period

Chadwick, David E.; Ignotz, George G.; Ignotz, Ronald A.; Lieberman, Irving

doi:10.1002/jcp.1041040110

Cited by 9 publications

(7 citation statements)

References 34 publications

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“…This same fraction could not enter the S phase i which quiescent when given 10% serum plus DRB. DRB also delayed Gl imulated near the transit by chicken embryo fibroblasts (5). Inhibitor studies of i-free medium for quiescent, serum-starved murine AKR-2B cells have similarthen shifted into ly shown that hnRNA synthesis is required for entry into the in Fig.…”

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confidence: 91%

Post-transcriptional control of the onset of DNA synthesis by an insulin-like growth factor.

Campisi¹,

Pardee²

1984

Mol. Cell. Biol.

114

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The control of eucaryotic cell proliferation is governed largely by a series of regulatory events which occur in the Gl phase of the cell cycle. When stimulated to proliferate, quiescent (GO) 3T3 fibroblasts require transcription, rapid translation, and three growth factors for the growth state transition. We examined exponentially growing 3T3 cells to relate the requirements for Gl transit to those necessary for the transition from the GO to the S phase. Cycling cells in the Gl phase required transcription, rapid translation, and a single growth factor (insulin-like growth factor [IGF] I) to initiate DNA synthesis. IGF I acted post-transcriptionally at a late Gl step. All cells in the Gl phase entered the S phase on schedule if either insulin (hyperphysiological concentration) or IGF I (subnanomolar concentration) was provided as the sole growth factor. In medium lacking all growth factors, only cells within 2 to 3 h of the S phase were able to initiate DNA synthesis. Similarly, cells within 2 to 3 h of the S phase were less dependent on transcription and translation for entry into the S phase. Cells responded very differently to inhibited translation than to growth factor deprivation. Cells in the early and mid-Gl phases did not progress toward the S phase during transcriptional or translational inhibition, and during translational inhibition they actually regressed from the S phase. In the absence of growth factors, however, these cells continued progressing toward the S phase, but still required IGF at a terminal step before initiating DNA synthesis. We conclude that a suboptimal condition causes cells to either progress or regress in the cell cycle rather than freezing them at their initial position. By using synchronized cultures, we also show that in contrast to earlier events, this final, IGF-dependent step did not require new trnscription. This result is in conrast to findings that other growth factors induce new transcription. We examined the requirements for Gl transit by using a chemically transformed 3T3 cell line (BPA31 cells) which has lost some but not all ability to regulate its growth. Early-and mid-Gl-phase BPA31 cells required transcription and translation to initiate DNA synthesis, although they did not regress from the S phase during translational inhibition. However, these cells did not need IGF for entry into the S phase.Eucaryotic cell growth is controlled by regulatory events which occur before the onset of DNA synthesis (2, 14, 23). The presynthesis or Gi phase of the cell cycle is generally viewed as a period during which cells prepare to initiate a round of DNA replication and cell division. In addition, cells in the Gl phase assess the feasibility of these processes in regard to the extracellular environment.Much of our understanding of the nature of growth regulation derives from studies with cultured murine 3T3 fibroblasts. These established, nontumorigenic embryonic cells show a stringent degree of growth control in culture, depending on the environment into which they are placed...

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Section: Downloaded Frommentioning

confidence: 91%

Post-transcriptional control of the onset of DNA synthesis by an insulin-like growth factor.

Campisi¹,

Pardee²

1984

Mol. Cell. Biol.

114

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“…Growth curves with hu IFN-a were essentially the same except that the cells were less sensitive. It has been shown that cell lines accumulating in GdG, at high density are IFN-sensitive (Creasey et al, 1980). U-251 MG could be synchronized by serum starvation at Go.…”

Section: A Ntiproli Ferati Ve Effectmentioning

confidence: 99%

Block of a glioma cell line in S by interferon

Lundblad

Lundgren

1981

Intl Journal of Cancer

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The human glioma cell line U-251 MG, with a well-characterized defect in growth control, was sensitive to the antiproliferative effects of human (fibroblast) interferon (IFN). IFN inhibited exponentially growing cells by increasing the number of cells in the S stage of the cell cycle. At the same time the number of cells in Go/G1 diminished. The rate of thymidine incorporation was decreased during the first cell cycle, with no prolongation of S. However, in synchronized cultures, the wave of cells with a S-phase content did not decrease over a time period several hours longer than the length of S measured by pulse labelling. Thus we conclude that, at a sufficient dose, the cells were unable to accomplish cell division as they prematurely stopped synthesizing DNA.

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“…DRB prolonged the intermitotic interval in cells cycling in the presence of the drug, but the effect was less in 15% than in 5% serum. After prolonged treatment of HeLa cells with DRB, the inhibition of heterogeneous nuclear RNA synthesis by DRB appeared to be reduced, which was not due to inactivation of DRB in the culture medium.The /&linked D-riboside of 5,6-dichlorobenzimidazole (DRB) (1-3) has been shown to inhibit the proliferation of animal cells in culture (1,4,5). In diploid human fibroblasts, the inhibition of cell proliferation appears to be reversible upon removal of DRB (5).…”

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“…The /&linked D-riboside of 5,6-dichlorobenzimidazole (DRB) (1-3) has been shown to inhibit the proliferation of animal cells in culture (1,4,5). In diploid human fibroblasts, the inhibition of cell proliferation appears to be reversible upon removal of DRB (5).…”

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Serum enhances the cycling and survival of HeLa cells treated with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole.

Tamm¹,

Kikuchi²,

Murphy³

1982

Proc. Natl. Acad. Sci. U.S.A.

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We have defined the growth kinetics of HeLa cell populations by determining the frequencies of mitoses and deaths and the lengths of intermitotic intervals. This was done by timelapse cinemicrography. Untreated control cells proliferated at closely similar rates in medium enriched with 5% or 15% fetal calf serum, with an average of 4% dividing and <0.1% dying per hr. The mean intermitotic interval was 16 hr during exponential growth of the control populations. In contrast, in cultures treated with 40 or 60 jIM 5,6-dichloro-1-g3-D-ribofuranosylbenzimidazole (DRB), a selective inhibitor of heterogeneous nuclear RNA synthesis, the frequency of mitoses was markedly and directly dependent on serum concentration, whereas the frequency ofdeaths was inversely dependent. DRB prolonged the intermitotic interval in cells cycling in the presence of the drug, but the effect was less in 15% than in 5% serum. After prolonged treatment of HeLa cells with DRB, the inhibition of heterogeneous nuclear RNA synthesis by DRB appeared to be reduced, which was not due to inactivation of DRB in the culture medium.The /&linked D-riboside of 5,6-dichlorobenzimidazole (DRB) (1-3) has been shown to inhibit the proliferation of animal cells in culture (1,4,5). In diploid human fibroblasts, the inhibition of cell proliferation appears to be reversible upon removal of DRB (5). DRB selectively inhibits the transcription of heterogeneous nuclear RNA (hnRNA) by prematurely terminating ==70-80% of the nascent chains 100-500 nucleotides downstream from initiation sites (6)(7)(8). The population of hnRNA chains that is susceptible to premature termination by DRB comprises the great majority ofmessage-containing transcripts, as indicated by the fact that 75 AM DRB inhibits the appearance of mRNA in the cytoplasm by >95% (9). In short-term experiments, the inhibition of RNA synthesis by DRB is promptly reversible upon removal of the compound and independent of serum concentration in the medium (10). After treatment of cells with DRB for 1 hr or longer, the rate of protein synthesis becomes depressed, probably as a result ofinhibition of mRNA synthesis (10, 11).In the course of an investigation to define the effects of DRB on the proliferation of aneuploid HeLa cells derived from an epidermoid carcinoma of the cervix, we made the unexpected observation that the extent of inhibition by DRB was inversely related to serum concentration in the medium. By using timelapse cinemicrography, we characterized the growth kinetics of DRB-treated cell populations in terms of three parameters: the frequency of mitoses, the frequency of deaths, and the length of the intermitotic intervals. We report that serum enhances both the cycling and the survival of cells treated with DRB for several days. MATERIALS AND METHODSCells and Culture Conditions. HeLa cells were grown to a density of 1.6-2 x 107 cells per flask (75 cm2 growth area) in reinforced Eagle's medium (12) supplemented with 5% fetal calf serum. Cells were trypsinized and passaged twice a week at a sp...

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Inhibitors of RNA synthesis and passage of chick embryo fibroblasts through the G1 period

Cited by 9 publications

References 34 publications

Post-transcriptional control of the onset of DNA synthesis by an insulin-like growth factor.

Post-transcriptional control of the onset of DNA synthesis by an insulin-like growth factor.

Block of a glioma cell line in S by interferon

Serum enhances the cycling and survival of HeLa cells treated with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole.

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