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Genetic instability as a consequence of inappropriate entry into and progression through S-phase.
Cancer Metastasis Rev. 1995 Mar; 14(1):59-73.CM

Abstract

The stability of the mammalian genome depends on the proper function of G1 and G2 cell cycle control mechanisms. Two tumor suppressors, p53 and retinoblastoma (Rb), play key roles in progression from G1 into S-phase. We address the mechanisms by which these proteins mediate a G1 arrest in response to DNA damage and limiting metabolic conditions. Gamma-irradiation induced a prolonged, p53-dependent G1 arrest associated with a long-term increase in the levels of the cdk-inhibitor p21WAFl/Cipl (p21). Microinjection of linear plasmid DNA also caused a G1 arrest. The p53-dependent arrest induced by inhibitors of UMP biosynthesis was reversible and occurred in the absence of detectable DNA damage. Both arrest mechanisms contribute to limiting the formation and propagation of damaged genomes. Cells containing mutant p53 but wild-type Rb do not generate methotrexate (Mtx) resistant variants. However, pre-treatment with DNA damaging agents prior to drug selection resulted in resistant clones containing amplified dihydrofolate reductase (DHFR) genes, suggesting that DNA breakage is a rate limiting step for gene amplification. The Mtx-induced arrest did not occur in cells with non-functional Rb. Rb acts as a negative regulator of the E2F transcription factors, and Rb-deficient primary mouse embryo fibroblasts (MEFs) produced elevated levels of mRNA and protein for key E2F target genes. Failure to prevent entry into S-phase in Rb-/- MEFs exposed to DNA-damaging or nutrient limiting conditions caused apoptosis and correlated with p53 induction. Taken together, these findings indicate a link between p53 and Rb function and suggest that their coordination insures correct entry into S-phase, minimizing the emergence of genetic variants.

Authors+Show Affiliations

Gene Expression Lab, Salk Institute, La Jolla, California, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review

Language

eng

PubMed ID

7606822

Citation

Almasan, A, et al. "Genetic Instability as a Consequence of Inappropriate Entry Into and Progression Through S-phase." Cancer Metastasis Reviews, vol. 14, no. 1, 1995, pp. 59-73.
Almasan A, Linke SP, Paulson TG, et al. Genetic instability as a consequence of inappropriate entry into and progression through S-phase. Cancer Metastasis Rev. 1995;14(1):59-73.
Almasan, A., Linke, S. P., Paulson, T. G., Huang, L. C., & Wahl, G. M. (1995). Genetic instability as a consequence of inappropriate entry into and progression through S-phase. Cancer Metastasis Reviews, 14(1), 59-73.
Almasan A, et al. Genetic Instability as a Consequence of Inappropriate Entry Into and Progression Through S-phase. Cancer Metastasis Rev. 1995;14(1):59-73. PubMed PMID: 7606822.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Genetic instability as a consequence of inappropriate entry into and progression through S-phase. AU - Almasan,A, AU - Linke,S P, AU - Paulson,T G, AU - Huang,L C, AU - Wahl,G M, PY - 1995/3/1/pubmed PY - 1995/3/1/medline PY - 1995/3/1/entrez SP - 59 EP - 73 JF - Cancer metastasis reviews JO - Cancer Metastasis Rev VL - 14 IS - 1 N2 - The stability of the mammalian genome depends on the proper function of G1 and G2 cell cycle control mechanisms. Two tumor suppressors, p53 and retinoblastoma (Rb), play key roles in progression from G1 into S-phase. We address the mechanisms by which these proteins mediate a G1 arrest in response to DNA damage and limiting metabolic conditions. Gamma-irradiation induced a prolonged, p53-dependent G1 arrest associated with a long-term increase in the levels of the cdk-inhibitor p21WAFl/Cipl (p21). Microinjection of linear plasmid DNA also caused a G1 arrest. The p53-dependent arrest induced by inhibitors of UMP biosynthesis was reversible and occurred in the absence of detectable DNA damage. Both arrest mechanisms contribute to limiting the formation and propagation of damaged genomes. Cells containing mutant p53 but wild-type Rb do not generate methotrexate (Mtx) resistant variants. However, pre-treatment with DNA damaging agents prior to drug selection resulted in resistant clones containing amplified dihydrofolate reductase (DHFR) genes, suggesting that DNA breakage is a rate limiting step for gene amplification. The Mtx-induced arrest did not occur in cells with non-functional Rb. Rb acts as a negative regulator of the E2F transcription factors, and Rb-deficient primary mouse embryo fibroblasts (MEFs) produced elevated levels of mRNA and protein for key E2F target genes. Failure to prevent entry into S-phase in Rb-/- MEFs exposed to DNA-damaging or nutrient limiting conditions caused apoptosis and correlated with p53 induction. Taken together, these findings indicate a link between p53 and Rb function and suggest that their coordination insures correct entry into S-phase, minimizing the emergence of genetic variants. SN - 0167-7659 UR - https://www.unboundmedicine.com/medline/citation/7606822/Genetic_instability_as_a_consequence_of_inappropriate_entry_into_and_progression_through_S_phase_ L2 - https://antibodies.cancer.gov/detail/CPTC-RB1-1 DB - PRIME DP - Unbound Medicine ER -