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Ribonucleotide reductase R2 gene expression and changes in drug sensitivity and genome stability.
- Source :
-
Cancer research [Cancer Res] 1997 Nov 01; Vol. 57 (21), pp. 4876-81. - Publication Year :
- 1997
-
Abstract
- Ribonucleotide reductase is a highly regulated, cell cycle-controlled activity that plays an important role in DNA synthesis and repair. Recent studies have shown that elevated expression of the rate-limiting R2 component of ribonucleotide reductase increases Raf-1 protein activation and mitogen-activated protein kinase activity and acts as a novel malignancy determinant in cooperation with activated oncogenes like H-ras. We show that hydroxyurea-resistant mouse L cells with elevated R2 gene expression and increased ribonucleotide reductase activity exhibit significantly decreased sensitivities to the chemotherapeutic compounds N-(phosphonacetyl)-L-aspartate (PALA) and methotrexate (MTX). Furthermore, BALB/c 3T3 cells containing a retroviral expression vector encoding the R2 sequence also showed decreased sensitivity to PALA and MTX when compared to cells containing the same vector but without the R2 coding region. Colonies that developed in the presence of PALA or MTX contained amplifications of the CAD or dihydrofolate reductase genes and exhibited wild-type p53 function as determined in sequence-specific p53 binding activity assays. NIH-3T3 cells containing the R2 retroviral expression vector also showed significantly decreased sensitivity to hydroxyurea and MTX but not to PALA. Furthermore, NIH-3T3 cells transfected with a vector containing the R2 sequence in antisense orientation exhibited increased sensitivity to hydroxyurea, PALA, and MTX. Similarly, mouse 10T1/2 cells that are highly transformed and drug resistant due to alterations in H-ras and a mutant oncogenic form of p53 exhibited significant increases in sensitivity to hydroxyurea, PALA, and MTX when transfected with a vector containing the R2 sequence in antisense orientation and compared to cells containing the same vector without the antisense sequence. These results indicate that altered expression of the R2 component is capable of significantly modifying drug sensitivity properties of tumor cells. We hypothesize that this occurs, at least in part, through a mechanism of increased genetic instability that is independent of direct p53 mutation or loss and involves R2 stimulation of the mitogen-activated protein kinase signal pathway.
- Subjects :
- 3T3 Cells drug effects
3T3 Cells enzymology
Animals
Antineoplastic Agents pharmacology
Antisense Elements (Genetics) metabolism
Aspartic Acid analogs & derivatives
Aspartic Acid pharmacology
Drug Resistance, Neoplasm genetics
Gene Amplification
Genes, p53 genetics
Genetic Vectors
Hydroxyurea pharmacology
L Cells drug effects
L Cells enzymology
Methotrexate pharmacology
Mice
Phosphonoacetic Acid analogs & derivatives
Phosphonoacetic Acid pharmacology
Retroviridae genetics
Ribonucleotide Reductases metabolism
Tumor Cells, Cultured drug effects
Tumor Cells, Cultured enzymology
Tumor Stem Cell Assay
Tumor Suppressor Protein p53 metabolism
Gene Expression Regulation, Enzymologic
Ribonucleotide Reductases genetics
Subjects
Details
- Language :
- English
- ISSN :
- 0008-5472
- Volume :
- 57
- Issue :
- 21
- Database :
- MEDLINE
- Journal :
- Cancer research
- Publication Type :
- Academic Journal
- Accession number :
- 9354452