Methylation-associated down-regulation of <it>RASSF1A </it>and up-regulation of <it>RASSF1C </it>in pancreatic endocrine tumors
<p>Abstract</p> <p>Background</p> <p><it>RASSF1A </it>gene silencing by DNA methylation has been suggested as a major event in pancreatic endocrine tumor (PET) but <it>RASSF1A </it>expression has never been studied. The <it>RASSF1 </it&g...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMC
2011-08-01
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| Series: | BMC Cancer |
| Online Access: | http://www.biomedcentral.com/1471-2407/11/351 |
| _version_ | 1818363406652014592 |
|---|---|
| author | Pelosi Giuseppe Boninsegna Letizia Debattisti Valentina Fumagalli Caterina Dandrea Mario Amato Eliana Malpeli Giorgio Falconi Massimo Scarpa Aldo |
| author_facet | Pelosi Giuseppe Boninsegna Letizia Debattisti Valentina Fumagalli Caterina Dandrea Mario Amato Eliana Malpeli Giorgio Falconi Massimo Scarpa Aldo |
| author_sort | Pelosi Giuseppe |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p><it>RASSF1A </it>gene silencing by DNA methylation has been suggested as a major event in pancreatic endocrine tumor (PET) but <it>RASSF1A </it>expression has never been studied. The <it>RASSF1 </it>locus contains two CpG islands (<it>A </it>and <it>C</it>) and generates seven transcripts (<it>RASSF1A</it>-<it>RASSF1G</it>) by differential promoter usage and alternative splicing.</p> <p>Methods</p> <p>We studied 20 primary PETs, their matched normal pancreas and three PET cell lines for the (i) methylation status of the <it>RASSF1 </it>CpG islands using methylation-specific PCR and pyrosequencing and (ii) expression of <it>RASSF1 </it>isoforms by quantitative RT-PCR in 13 cases. CpG island A methylation was evaluated by methylation-specific PCR (MSP) and by quantitative methylation-specific PCR (qMSP); pyrosequencing was applied to quantify the methylation of 51 CpGs also encompassing those explored by MSP and qMSP approaches.</p> <p>Results</p> <p>MSP detected methylation in 16/20 (80%) PETs and 13/20 (65%) normal pancreas. At qMSP, 11/20 PETs (55%) and 9/20 (45%) normals were methylated in at least 20% of <it>RASSF1A </it>alleles.</p> <p>Pyrosequencing showed variable distribution and levels of methylation within and among samples, with PETs having average methylation higher than normals in 15/20 (75%) cases (<it>P </it>= 0.01). The evaluation of mRNA expression of <it>RASSF1 </it>variants showed that: i) <it>RASSF1A </it>was always expressed in PET and normal tissues, but it was, on average, expressed 6.8 times less in PET (<it>P </it>= 0.003); ii) <it>RASSF1A </it>methylation inversely correlated with its expression; iii) <it>RASSF1 </it>isoforms were rarely found, except for <it>RASSF1B </it>that was always expressed and <it>RASSF1C </it>whose expression was 11.4 times higher in PET than in normal tissue (<it>P </it>= 0.001). A correlation between <it>RASSF1A </it>expression and gene methylation was found in two of the three PET cell lines, which also showed a significant increase in <it>RASSF1A </it>expression upon demethylating treatment.</p> <p>Conclusions</p> <p><it>RASSF1A </it>gene methylation in PET is higher than normal pancreas in no more than 75% of cases and as such it cannot be considered a marker for this neoplasm. <it>RASSF1A </it>is always expressed in PET and normal pancreas and its levels are inversely correlated with gene methylation. Isoform <it>RASSF1C </it>is overexpressed in PET and the recent demonstration of its involvement in the regulation of the Wnt pathway points to a potential pathogenetic role in tumor development.</p> |
| first_indexed | 2024-12-13T21:47:58Z |
| format | Article |
| id | doaj.art-cf9441b84cb94ca2906e016dfe85c64a |
| institution | Directory Open Access Journal |
| issn | 1471-2407 |
| language | English |
| last_indexed | 2024-12-13T21:47:58Z |
| publishDate | 2011-08-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Cancer |
| spelling | doaj.art-cf9441b84cb94ca2906e016dfe85c64a2022-12-21T23:30:22ZengBMCBMC Cancer1471-24072011-08-0111135110.1186/1471-2407-11-351Methylation-associated down-regulation of <it>RASSF1A </it>and up-regulation of <it>RASSF1C </it>in pancreatic endocrine tumorsPelosi GiuseppeBoninsegna LetiziaDebattisti ValentinaFumagalli CaterinaDandrea MarioAmato ElianaMalpeli GiorgioFalconi MassimoScarpa Aldo<p>Abstract</p> <p>Background</p> <p><it>RASSF1A </it>gene silencing by DNA methylation has been suggested as a major event in pancreatic endocrine tumor (PET) but <it>RASSF1A </it>expression has never been studied. The <it>RASSF1 </it>locus contains two CpG islands (<it>A </it>and <it>C</it>) and generates seven transcripts (<it>RASSF1A</it>-<it>RASSF1G</it>) by differential promoter usage and alternative splicing.</p> <p>Methods</p> <p>We studied 20 primary PETs, their matched normal pancreas and three PET cell lines for the (i) methylation status of the <it>RASSF1 </it>CpG islands using methylation-specific PCR and pyrosequencing and (ii) expression of <it>RASSF1 </it>isoforms by quantitative RT-PCR in 13 cases. CpG island A methylation was evaluated by methylation-specific PCR (MSP) and by quantitative methylation-specific PCR (qMSP); pyrosequencing was applied to quantify the methylation of 51 CpGs also encompassing those explored by MSP and qMSP approaches.</p> <p>Results</p> <p>MSP detected methylation in 16/20 (80%) PETs and 13/20 (65%) normal pancreas. At qMSP, 11/20 PETs (55%) and 9/20 (45%) normals were methylated in at least 20% of <it>RASSF1A </it>alleles.</p> <p>Pyrosequencing showed variable distribution and levels of methylation within and among samples, with PETs having average methylation higher than normals in 15/20 (75%) cases (<it>P </it>= 0.01). The evaluation of mRNA expression of <it>RASSF1 </it>variants showed that: i) <it>RASSF1A </it>was always expressed in PET and normal tissues, but it was, on average, expressed 6.8 times less in PET (<it>P </it>= 0.003); ii) <it>RASSF1A </it>methylation inversely correlated with its expression; iii) <it>RASSF1 </it>isoforms were rarely found, except for <it>RASSF1B </it>that was always expressed and <it>RASSF1C </it>whose expression was 11.4 times higher in PET than in normal tissue (<it>P </it>= 0.001). A correlation between <it>RASSF1A </it>expression and gene methylation was found in two of the three PET cell lines, which also showed a significant increase in <it>RASSF1A </it>expression upon demethylating treatment.</p> <p>Conclusions</p> <p><it>RASSF1A </it>gene methylation in PET is higher than normal pancreas in no more than 75% of cases and as such it cannot be considered a marker for this neoplasm. <it>RASSF1A </it>is always expressed in PET and normal pancreas and its levels are inversely correlated with gene methylation. Isoform <it>RASSF1C </it>is overexpressed in PET and the recent demonstration of its involvement in the regulation of the Wnt pathway points to a potential pathogenetic role in tumor development.</p>http://www.biomedcentral.com/1471-2407/11/351 |
| spellingShingle | Pelosi Giuseppe Boninsegna Letizia Debattisti Valentina Fumagalli Caterina Dandrea Mario Amato Eliana Malpeli Giorgio Falconi Massimo Scarpa Aldo Methylation-associated down-regulation of <it>RASSF1A </it>and up-regulation of <it>RASSF1C </it>in pancreatic endocrine tumors BMC Cancer |
| title | Methylation-associated down-regulation of <it>RASSF1A </it>and up-regulation of <it>RASSF1C </it>in pancreatic endocrine tumors |
| title_full | Methylation-associated down-regulation of <it>RASSF1A </it>and up-regulation of <it>RASSF1C </it>in pancreatic endocrine tumors |
| title_fullStr | Methylation-associated down-regulation of <it>RASSF1A </it>and up-regulation of <it>RASSF1C </it>in pancreatic endocrine tumors |
| title_full_unstemmed | Methylation-associated down-regulation of <it>RASSF1A </it>and up-regulation of <it>RASSF1C </it>in pancreatic endocrine tumors |
| title_short | Methylation-associated down-regulation of <it>RASSF1A </it>and up-regulation of <it>RASSF1C </it>in pancreatic endocrine tumors |
| title_sort | methylation associated down regulation of it rassf1a it and up regulation of it rassf1c it in pancreatic endocrine tumors |
| url | http://www.biomedcentral.com/1471-2407/11/351 |
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