Limits...
Loss of imprinting of IGF2 correlates with hypermethylation of the H19 differentially methylated region in hepatoblastoma.

Honda S, Arai Y, Haruta M, Sasaki F, Ohira M, Yamaoka H, Horie H, Nakagawara A, Hiyama E, Todo S, Kaneko Y - Br. J. Cancer (2008)

Bottom Line: Increased IGF2 expression with predominant embryonic P3 transcript was found in the majority of HBs with ROI and foetal livers.In contrast to the earlier reports, our findings suggest that the disruption of the enhancer competition model reported in Wilms' tumour may also occur in HB.Both frequencies of LOH and LOI seem to be lower in HB than in Wilms' tumour, reflecting the different tissue origins.

View Article: PubMed Central - PubMed

Affiliation: Department of Cancer Diagnosis, Saitama Cancer Center, Research Institute for Clinical Oncology, 818 Komuro, Ina, Saitama 362-0806, Japan.

ABSTRACT
IGF2, a maternally imprinted foetal growth factor gene, is implicated in many childhood tumours including hepatoblastoma (HB); however, the genetic and epigenetic alterations have not comprehensively been studied. We analysed the methylation status of the H19 differentially methylated region (DMR), loss of heterozygosity (LOH) and allelic expression of IGF2 in 54 HB tumours, and found that 12 tumours (22%) with LOH, 9 (17%) with loss of imprinting (LOI) and 33 (61%) with retention of imprinting (ROI). Biallelic and monoallelic IGF2 expressions correlated with hypermethylation and normal methylation of H19 DMR, respectively, in two tumours with LOI and seven tumours with ROI. Quantitative RT-PCR analysis showed minimal expression of H19 mRNA and substantial expression of IGF2 mRNA in tumours with LOH or LOI, and substantial expression of both H19 and IGF2 mRNAs in tumours with ROI. Increased IGF2 expression with predominant embryonic P3 transcript was found in the majority of HBs with ROI and foetal livers. In contrast to the earlier reports, our findings suggest that the disruption of the enhancer competition model reported in Wilms' tumour may also occur in HB. Both frequencies of LOH and LOI seem to be lower in HB than in Wilms' tumour, reflecting the different tissue origins.

Show MeSH

Related in: MedlinePlus

Results of quantitative real-time RT–PCR analysis of IGF2 and H19 mRNAs. Relative mRNA (Y axis) of total IGF2 (open rectangles) and H19 (closed rectangles) is plotted in 3 tumours with UPD, in 1 tumour with 11p15 loss, in 3 tumours with LOI, in 13 tumours with ROI, in 2 cell lines, in foetal liver total RNA and in adjacent normal liver tissues (a mean value of 3 samples). Tumours in each group are arranged in order by the levels of IGF2 mRNA. Numbers below X axis indicate the tumour number shown in Table 1. IGF2 status (UPD, loss of 11p15, LOI and ROI) and methylation status of CTCF6 at H19 DMR (hypermethylated or normally methylated) are shown above the graph. Nine tumours (nos. 1–3, 11, 13–15, 25 and 27) and two cell lines expressed a minimal amount of H19 mRNA, which was shown as zero in the graph. Similarly, HuH6 expressed a minimal amount of IGF2 mRNA, which was shown as zero in the graph.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2600691&req=5

fig2: Results of quantitative real-time RT–PCR analysis of IGF2 and H19 mRNAs. Relative mRNA (Y axis) of total IGF2 (open rectangles) and H19 (closed rectangles) is plotted in 3 tumours with UPD, in 1 tumour with 11p15 loss, in 3 tumours with LOI, in 13 tumours with ROI, in 2 cell lines, in foetal liver total RNA and in adjacent normal liver tissues (a mean value of 3 samples). Tumours in each group are arranged in order by the levels of IGF2 mRNA. Numbers below X axis indicate the tumour number shown in Table 1. IGF2 status (UPD, loss of 11p15, LOI and ROI) and methylation status of CTCF6 at H19 DMR (hypermethylated or normally methylated) are shown above the graph. Nine tumours (nos. 1–3, 11, 13–15, 25 and 27) and two cell lines expressed a minimal amount of H19 mRNA, which was shown as zero in the graph. Similarly, HuH6 expressed a minimal amount of IGF2 mRNA, which was shown as zero in the graph.

Mentions: Quantitative real-time reverse transcription-PCR analysis showed that although 15 of 20 tumours had a higher level of IGF2 mRNA than normal liver tissues, 15 of 20 tumours had a lower level of H19 mRNA than normal liver tissues (Table 1 and Figure 2). All 3 tumours with UPD, 1 of 1 with 11p15 loss, 1 of 3 with LOI and 10 of 13 with ROI, expressed higher levels of IGF2 mRNA than normal liver tissues. There was no significant difference in IGF2 mRNA levels between 3 tumours with UPD or 7 tumours with IGF2 alterations; that is UPD, 11p15 loss or LOI, and 13 tumours with ROI. In contrast, 7 tumours with IGF2 alterations expressed very low levels of H19 mRNA, whereas 11 of 13 tumours with ROI expressed a substantial amount of H19 mRNA; 2 tumours (nos. 25 and 27) with ROI expressed very low levels of H19 mRNA. H19 mRNA levels were higher in 13 HB tumours with ROI than in 7 HB tumours with IGF2 alterations (P<0.01 by Welch's t-test). Although HepG2 with UPD had a higher level of IGF2 mRNA than normal liver tissues, HuH6 with LOI had a very low level of IGF2 mRNA. H19 mRNA levels were very low in both cell lines.


Loss of imprinting of IGF2 correlates with hypermethylation of the H19 differentially methylated region in hepatoblastoma.

Honda S, Arai Y, Haruta M, Sasaki F, Ohira M, Yamaoka H, Horie H, Nakagawara A, Hiyama E, Todo S, Kaneko Y - Br. J. Cancer (2008)

Results of quantitative real-time RT–PCR analysis of IGF2 and H19 mRNAs. Relative mRNA (Y axis) of total IGF2 (open rectangles) and H19 (closed rectangles) is plotted in 3 tumours with UPD, in 1 tumour with 11p15 loss, in 3 tumours with LOI, in 13 tumours with ROI, in 2 cell lines, in foetal liver total RNA and in adjacent normal liver tissues (a mean value of 3 samples). Tumours in each group are arranged in order by the levels of IGF2 mRNA. Numbers below X axis indicate the tumour number shown in Table 1. IGF2 status (UPD, loss of 11p15, LOI and ROI) and methylation status of CTCF6 at H19 DMR (hypermethylated or normally methylated) are shown above the graph. Nine tumours (nos. 1–3, 11, 13–15, 25 and 27) and two cell lines expressed a minimal amount of H19 mRNA, which was shown as zero in the graph. Similarly, HuH6 expressed a minimal amount of IGF2 mRNA, which was shown as zero in the graph.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2600691&req=5

fig2: Results of quantitative real-time RT–PCR analysis of IGF2 and H19 mRNAs. Relative mRNA (Y axis) of total IGF2 (open rectangles) and H19 (closed rectangles) is plotted in 3 tumours with UPD, in 1 tumour with 11p15 loss, in 3 tumours with LOI, in 13 tumours with ROI, in 2 cell lines, in foetal liver total RNA and in adjacent normal liver tissues (a mean value of 3 samples). Tumours in each group are arranged in order by the levels of IGF2 mRNA. Numbers below X axis indicate the tumour number shown in Table 1. IGF2 status (UPD, loss of 11p15, LOI and ROI) and methylation status of CTCF6 at H19 DMR (hypermethylated or normally methylated) are shown above the graph. Nine tumours (nos. 1–3, 11, 13–15, 25 and 27) and two cell lines expressed a minimal amount of H19 mRNA, which was shown as zero in the graph. Similarly, HuH6 expressed a minimal amount of IGF2 mRNA, which was shown as zero in the graph.
Mentions: Quantitative real-time reverse transcription-PCR analysis showed that although 15 of 20 tumours had a higher level of IGF2 mRNA than normal liver tissues, 15 of 20 tumours had a lower level of H19 mRNA than normal liver tissues (Table 1 and Figure 2). All 3 tumours with UPD, 1 of 1 with 11p15 loss, 1 of 3 with LOI and 10 of 13 with ROI, expressed higher levels of IGF2 mRNA than normal liver tissues. There was no significant difference in IGF2 mRNA levels between 3 tumours with UPD or 7 tumours with IGF2 alterations; that is UPD, 11p15 loss or LOI, and 13 tumours with ROI. In contrast, 7 tumours with IGF2 alterations expressed very low levels of H19 mRNA, whereas 11 of 13 tumours with ROI expressed a substantial amount of H19 mRNA; 2 tumours (nos. 25 and 27) with ROI expressed very low levels of H19 mRNA. H19 mRNA levels were higher in 13 HB tumours with ROI than in 7 HB tumours with IGF2 alterations (P<0.01 by Welch's t-test). Although HepG2 with UPD had a higher level of IGF2 mRNA than normal liver tissues, HuH6 with LOI had a very low level of IGF2 mRNA. H19 mRNA levels were very low in both cell lines.

Bottom Line: Increased IGF2 expression with predominant embryonic P3 transcript was found in the majority of HBs with ROI and foetal livers.In contrast to the earlier reports, our findings suggest that the disruption of the enhancer competition model reported in Wilms' tumour may also occur in HB.Both frequencies of LOH and LOI seem to be lower in HB than in Wilms' tumour, reflecting the different tissue origins.

View Article: PubMed Central - PubMed

Affiliation: Department of Cancer Diagnosis, Saitama Cancer Center, Research Institute for Clinical Oncology, 818 Komuro, Ina, Saitama 362-0806, Japan.

ABSTRACT
IGF2, a maternally imprinted foetal growth factor gene, is implicated in many childhood tumours including hepatoblastoma (HB); however, the genetic and epigenetic alterations have not comprehensively been studied. We analysed the methylation status of the H19 differentially methylated region (DMR), loss of heterozygosity (LOH) and allelic expression of IGF2 in 54 HB tumours, and found that 12 tumours (22%) with LOH, 9 (17%) with loss of imprinting (LOI) and 33 (61%) with retention of imprinting (ROI). Biallelic and monoallelic IGF2 expressions correlated with hypermethylation and normal methylation of H19 DMR, respectively, in two tumours with LOI and seven tumours with ROI. Quantitative RT-PCR analysis showed minimal expression of H19 mRNA and substantial expression of IGF2 mRNA in tumours with LOH or LOI, and substantial expression of both H19 and IGF2 mRNAs in tumours with ROI. Increased IGF2 expression with predominant embryonic P3 transcript was found in the majority of HBs with ROI and foetal livers. In contrast to the earlier reports, our findings suggest that the disruption of the enhancer competition model reported in Wilms' tumour may also occur in HB. Both frequencies of LOH and LOI seem to be lower in HB than in Wilms' tumour, reflecting the different tissue origins.

Show MeSH
Related in: MedlinePlus