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Genomic analysis of microRNA time-course expression in liver of mice treated with genotoxic carcinogen N-ethyl-N-nitrosourea.

Li Z, Branham WS, Dial SL, Wang Y, Guo L, Shi L, Chen T - BMC Genomics (2010)

Bottom Line: The magnitude of the expression change varied with time with the highest changes at PTDs 7 or 15 for most of the DEMs. In silico functional analysis of the DEMs at PTDs 7 and 15 indicated that the major functions of these ENU-induced DEMs were associated with DNA damage, DNA repair, apoptosis and other processes related to carcinogenesis.Our results showed that many miRNAs changed their expression to respond the exposure of the genotoxic carcinogen ENU and the number and magnitude of the changes were highest at PTDs 7 to 15.Thus, one to two weeks after the exposure is the best time for miRNA expression sampling.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, FDA, Jefferson, AR 72079, USA.

ABSTRACT

Background: Dysregulated expression of microRNAs (miRNAs) has been previously observed in human cancer tissues and shown promise in defining tumor status. However, there is little information as to if or when expression changes of miRNAs occur in normal tissues after carcinogen exposure.

Results: To explore the possible time-course changes of miRNA expression induced by a carcinogen, we treated mice with one dose of 120 mg/kg N-ethyl-N-nitrosourea (ENU), a model genotoxic carcinogen, and vehicle control. The miRNA expression profiles were assessed in the mouse livers in a time-course design. miRNAs were isolated from the livers at days 1, 3, 7, 15, 30 and 120 after the treatment and their expression was determined using a miRNA PCR Array. Principal component analysis of the miRNA expression profiles showed that miRNA expression at post-treatment days (PTDs) 7 and 15 were different from those at the other time points and the control. The number of differentially expressed miRNAs (DEMs) changed over time (3, 5, 14, 32, 5 and 5 at PTDs 1, 3, 7, 15, 30 and 120, respectively). The magnitude of the expression change varied with time with the highest changes at PTDs 7 or 15 for most of the DEMs. In silico functional analysis of the DEMs at PTDs 7 and 15 indicated that the major functions of these ENU-induced DEMs were associated with DNA damage, DNA repair, apoptosis and other processes related to carcinogenesis.

Conclusion: Our results showed that many miRNAs changed their expression to respond the exposure of the genotoxic carcinogen ENU and the number and magnitude of the changes were highest at PTDs 7 to 15. Thus, one to two weeks after the exposure is the best time for miRNA expression sampling.

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Related in: MedlinePlus

The temporal expression changes of three miR-34 family members and one miR-762 family member as determined by PCR arrays and individual TaqMan assays. The data for each time point are the mean of 4 or 5 samples with its standard error. The asterisk indicates there is a significant difference between the treatment and control at that time point (p < 0.01).
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Figure 3: The temporal expression changes of three miR-34 family members and one miR-762 family member as determined by PCR arrays and individual TaqMan assays. The data for each time point are the mean of 4 or 5 samples with its standard error. The asterisk indicates there is a significant difference between the treatment and control at that time point (p < 0.01).

Mentions: The miR-34 family is worth special attention because two of its members, mmu-miR-34a and mmu-miR-34b-5p, were significantly up-regulated one day after ENU exposure and maintained increased expression at the 5 subsequent time points up to PTD 30, while another family member, mmu-miR-34c, displayed significant over-expression at multiple time points from PTD 3 to 30. To serve as a confirmation of the data from RT2-mouse miRNA PCR Array, a different real-time PCR platform, TaqMan miRNA assay, was used to measure the time-course changes of miR-34 family members induced by the ENU treatment using the same RNA samples. For TaqMan miRNA assay, all of the samples were reversely transcribed simultaneously and the PCRs for the different samples were run in the same plates. This procedure can greatly reduce the inter-plate variability that could be produced when PCR arrays are used. A comparison of miR-34 family miRNA expression measured by the two different platforms is shown in Figure 3. The results from the two real-time PCR assay platforms are very consistent and show similar temporal kinetics of miRNA expression for miR-34 family miRNAs, rising from day 1 or 3, reaching peaks at day 15, and decreasing until the end of observation, day 120. Another miRNA, mmu-miR-762 that is not similar with miR-34 family miRNAs in sequence, were also examined to confirm the array data. The consistency between two platforms was also observed (Figure 3).


Genomic analysis of microRNA time-course expression in liver of mice treated with genotoxic carcinogen N-ethyl-N-nitrosourea.

Li Z, Branham WS, Dial SL, Wang Y, Guo L, Shi L, Chen T - BMC Genomics (2010)

The temporal expression changes of three miR-34 family members and one miR-762 family member as determined by PCR arrays and individual TaqMan assays. The data for each time point are the mean of 4 or 5 samples with its standard error. The asterisk indicates there is a significant difference between the treatment and control at that time point (p < 0.01).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3091750&req=5

Figure 3: The temporal expression changes of three miR-34 family members and one miR-762 family member as determined by PCR arrays and individual TaqMan assays. The data for each time point are the mean of 4 or 5 samples with its standard error. The asterisk indicates there is a significant difference between the treatment and control at that time point (p < 0.01).
Mentions: The miR-34 family is worth special attention because two of its members, mmu-miR-34a and mmu-miR-34b-5p, were significantly up-regulated one day after ENU exposure and maintained increased expression at the 5 subsequent time points up to PTD 30, while another family member, mmu-miR-34c, displayed significant over-expression at multiple time points from PTD 3 to 30. To serve as a confirmation of the data from RT2-mouse miRNA PCR Array, a different real-time PCR platform, TaqMan miRNA assay, was used to measure the time-course changes of miR-34 family members induced by the ENU treatment using the same RNA samples. For TaqMan miRNA assay, all of the samples were reversely transcribed simultaneously and the PCRs for the different samples were run in the same plates. This procedure can greatly reduce the inter-plate variability that could be produced when PCR arrays are used. A comparison of miR-34 family miRNA expression measured by the two different platforms is shown in Figure 3. The results from the two real-time PCR assay platforms are very consistent and show similar temporal kinetics of miRNA expression for miR-34 family miRNAs, rising from day 1 or 3, reaching peaks at day 15, and decreasing until the end of observation, day 120. Another miRNA, mmu-miR-762 that is not similar with miR-34 family miRNAs in sequence, were also examined to confirm the array data. The consistency between two platforms was also observed (Figure 3).

Bottom Line: The magnitude of the expression change varied with time with the highest changes at PTDs 7 or 15 for most of the DEMs. In silico functional analysis of the DEMs at PTDs 7 and 15 indicated that the major functions of these ENU-induced DEMs were associated with DNA damage, DNA repair, apoptosis and other processes related to carcinogenesis.Our results showed that many miRNAs changed their expression to respond the exposure of the genotoxic carcinogen ENU and the number and magnitude of the changes were highest at PTDs 7 to 15.Thus, one to two weeks after the exposure is the best time for miRNA expression sampling.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, FDA, Jefferson, AR 72079, USA.

ABSTRACT

Background: Dysregulated expression of microRNAs (miRNAs) has been previously observed in human cancer tissues and shown promise in defining tumor status. However, there is little information as to if or when expression changes of miRNAs occur in normal tissues after carcinogen exposure.

Results: To explore the possible time-course changes of miRNA expression induced by a carcinogen, we treated mice with one dose of 120 mg/kg N-ethyl-N-nitrosourea (ENU), a model genotoxic carcinogen, and vehicle control. The miRNA expression profiles were assessed in the mouse livers in a time-course design. miRNAs were isolated from the livers at days 1, 3, 7, 15, 30 and 120 after the treatment and their expression was determined using a miRNA PCR Array. Principal component analysis of the miRNA expression profiles showed that miRNA expression at post-treatment days (PTDs) 7 and 15 were different from those at the other time points and the control. The number of differentially expressed miRNAs (DEMs) changed over time (3, 5, 14, 32, 5 and 5 at PTDs 1, 3, 7, 15, 30 and 120, respectively). The magnitude of the expression change varied with time with the highest changes at PTDs 7 or 15 for most of the DEMs. In silico functional analysis of the DEMs at PTDs 7 and 15 indicated that the major functions of these ENU-induced DEMs were associated with DNA damage, DNA repair, apoptosis and other processes related to carcinogenesis.

Conclusion: Our results showed that many miRNAs changed their expression to respond the exposure of the genotoxic carcinogen ENU and the number and magnitude of the changes were highest at PTDs 7 to 15. Thus, one to two weeks after the exposure is the best time for miRNA expression sampling.

Show MeSH
Related in: MedlinePlus