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Effects of tiazofurin on globin and proto-oncogene expression in K562 erythroleukemia cells
S M Kharbanda1, K Miyazaki, H Takeyama
1Laboratory of Clinical Pharmacology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115.
Abstract:
Tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide, NSC 286193) is a synthetic nucleoside inhibitor of inosine monophosphate dehydrogenase. This agent has recently been shown to induce differentiation of human leukemia cell lines. In the present study, we have monitored the effects of tiazofurin on differentiation and proto-oncogene expression in K562 erythroleukemia cells. Tiazofurin induced K562 cell hemoglobin production in a concentration-dependent manner. This induction of a differentiated phenotype was also associated with a loss of proliferative capacity. In contrast to the reversible effects of hemin on induction of K562 cell hemoglobin synthesis, the effects of tiazofurin were irreversible. Northern blot analysis of K562 cells treated with 10 microM tiazofurin demonstrated the accumulation of alpha- and gamma-globin mRNA. The results also demonstrate that there was little if any effect of tiazofurin on levels of c-myc, c-myb, or c-abl mRNA. Furthermore, there were no detectable changes in Ki-ras, Ha-ras or N-ras expression at the mRNA and protein levels in tiazofurin-treated K562 cells. These findings suggest that tiazofurin induces changes in levels of globin transcripts but has little if any effect on c-myc, c-myb, c-abl, or c-ras gene expression in K562 cells.
Insights
Tiazofurin, a novel leukemia cell differentiation agent, irreversibly induces hemoglobin production in K562 cells. This drug impacts globin mRNA levels but does not affect key proto-oncogene expression.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Tiazofurin is a synthetic nucleoside analog.
- It acts as an inhibitor of inosine monophosphate dehydrogenase.
- Tiazofurin has demonstrated potential in inducing differentiation of human leukemia cell lines.
Purpose of the Study:
- To investigate the effects of tiazofurin on differentiation and proto-oncogene expression in K562 erythroleukemia cells.
- To compare the differentiation effects of tiazofurin with hemin.
Main Methods:
- K562 erythroleukemia cells were treated with varying concentrations of tiazofurin.
- Hemoglobin production was measured to assess differentiation.
- Northern blot analysis was used to examine the expression of alpha- and gamma-globin mRNA.
- Expression levels of proto-oncogenes (c-myc, c-myb, c-abl, and ras family members) were analyzed at both mRNA and protein levels.
Main Results:
- Tiazofurin induced K562 cell hemoglobin production in a concentration-dependent manner.
- The differentiation induced by tiazofurin was irreversible, unlike the effects of hemin.
- Tiazofurin treatment led to the accumulation of alpha- and gamma-globin mRNA.
- No significant changes were observed in the expression of c-myc, c-myb, c-abl, or ras family genes (Ki-ras, Ha-ras, N-ras) at the mRNA or protein levels.
Conclusions:
- Tiazofurin effectively induces differentiation in K562 erythroleukemia cells, characterized by increased hemoglobin production.
- The differentiation effects of tiazofurin are irreversible and associated with altered globin mRNA levels.
- Tiazofurin does not appear to modulate the expression of critical proto-oncogenes such as c-myc, c-myb, c-abl, or ras family members in this cellular model.