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Geographical mapping of a multifocal thyroid tumour using genetic alteration analysis & miRNA profiling.

Aherne ST, Smyth PC, Flavin RJ, Russell SM, Denning KM, Li JH, Guenther SM, O'Leary JJ, Sheils OM - Mol. Cancer (2008)

Bottom Line: Several studies have investigated the genetic alteration status of multifocal thyroid tumours, with discordant results.Our data corroborated miRNAs previously discovered in this carcinoma, and additional miRNAs linked to various processes involved in tumour growth and proliferation.The initial genetic alteration analysis indicated that pluriform PTC did not necessarily evolve from classic PTC progenitor foci.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Histopathology, Trinity College, Dublin, Ireland. ahernesi@tcd.ie

ABSTRACT

Background: Papillary thyroid carcinoma (PTC) frequently presents as multiple tumour-foci within a single thyroid gland or pluriform, with synchronous tumours comprising different histological variants, raising questions regarding its clonality. Among the genetic aberrations described in PTC, the BRAF V600E mutation and ret/PTC activation occur most commonly. Several studies have investigated the genetic alteration status of multifocal thyroid tumours, with discordant results. To address the question of clonality this study examined disparate geographical and morphological areas from a single PTC (classic PTC, insular and anaplastic foci, and tumour cells adjacent to vascular invasion and lymphocytic infiltrate) for the presence of ret/PTC 1 or BRAF mutations. Moreover, we wanted to investigate the consistency of miRNA signatures within disparate areas of a tumour, and geographical data was further correlated with expression profiles of 330 different miRNAs. Putative miRNA gene targets were predicted for differentially regulated miRNAs and immunohistochemistry was performed on tissue sections in an effort to investigate phenotypic variations in microvascular density (MVD), and cytokeratin and p53 protein expression levels.

Results: All of the morphological areas proved negative for ret/PTC 1 rearrangement. Two distinct foci with classic morphology harboured the BRAF mutation. All other regions, including the insular and anaplastic areas were negative for the mutation. MiRNA profiles were found to distinguish tumours containing the BRAF mutation from the other tumour types, and to differentiate between the more aggressive insular & anaplastic tumours, and the classic variant. Our data corroborated miRNAs previously discovered in this carcinoma, and additional miRNAs linked to various processes involved in tumour growth and proliferation.

Conclusion: The initial genetic alteration analysis indicated that pluriform PTC did not necessarily evolve from classic PTC progenitor foci. Analysis of miRNA profiles however provided an interesting variation on the clonality question. While hierarchical clustering analysis of miRNA expression supported the hypothesis that discrete areas did not evolve from clonal expansion of tumour cells, it did not exclude the possibility of independent mutational events suggesting both phenomena might occur simultaneously within a tumour to enhance cancer progression in geographical micro-environments within a tumour.

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H&E & immunohistochemistry staining of thyroid sections. (A) H&E stained sections of normal thyroid, classic PTC, anaplastic thyroid cancer, and insular carcinoma. (B) Immunohistochemical staining for CD34 in normal, PTC, and anaplastic sections. (C) Immunohistochemical staining for p53 in normal, PTC, and anaplastic sections. (D) Immunohistochemical staining for cytokeratin in normal thyroid, and in an area showing classic PTC and anaplastic cancer areas.
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Figure 4: H&E & immunohistochemistry staining of thyroid sections. (A) H&E stained sections of normal thyroid, classic PTC, anaplastic thyroid cancer, and insular carcinoma. (B) Immunohistochemical staining for CD34 in normal, PTC, and anaplastic sections. (C) Immunohistochemical staining for p53 in normal, PTC, and anaplastic sections. (D) Immunohistochemical staining for cytokeratin in normal thyroid, and in an area showing classic PTC and anaplastic cancer areas.

Mentions: Although these are predicted results, they may lead us in the right direction in revealing the biological functioning of these miRNAs. Therefore, in an effort to explore the behaviour of some cellular processes across different areas of morphology in a multifocal tumour, we performed some immunohistochemistry on our tissue sections (Figure 4). CD34 was analysed in an effort to assess microvascular density (MVD), cytokeratin to stain epithelial cells and view differentiation status, and p53 as it is commonly mutated in this cancer. Morphological assessment and evaluation of staining intensity may hint at performance of some of the pathways mentioned previously such as angiogenesis and cytoskeletal regulation and wnt signaling.


Geographical mapping of a multifocal thyroid tumour using genetic alteration analysis & miRNA profiling.

Aherne ST, Smyth PC, Flavin RJ, Russell SM, Denning KM, Li JH, Guenther SM, O'Leary JJ, Sheils OM - Mol. Cancer (2008)

H&E & immunohistochemistry staining of thyroid sections. (A) H&E stained sections of normal thyroid, classic PTC, anaplastic thyroid cancer, and insular carcinoma. (B) Immunohistochemical staining for CD34 in normal, PTC, and anaplastic sections. (C) Immunohistochemical staining for p53 in normal, PTC, and anaplastic sections. (D) Immunohistochemical staining for cytokeratin in normal thyroid, and in an area showing classic PTC and anaplastic cancer areas.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2612696&req=5

Figure 4: H&E & immunohistochemistry staining of thyroid sections. (A) H&E stained sections of normal thyroid, classic PTC, anaplastic thyroid cancer, and insular carcinoma. (B) Immunohistochemical staining for CD34 in normal, PTC, and anaplastic sections. (C) Immunohistochemical staining for p53 in normal, PTC, and anaplastic sections. (D) Immunohistochemical staining for cytokeratin in normal thyroid, and in an area showing classic PTC and anaplastic cancer areas.
Mentions: Although these are predicted results, they may lead us in the right direction in revealing the biological functioning of these miRNAs. Therefore, in an effort to explore the behaviour of some cellular processes across different areas of morphology in a multifocal tumour, we performed some immunohistochemistry on our tissue sections (Figure 4). CD34 was analysed in an effort to assess microvascular density (MVD), cytokeratin to stain epithelial cells and view differentiation status, and p53 as it is commonly mutated in this cancer. Morphological assessment and evaluation of staining intensity may hint at performance of some of the pathways mentioned previously such as angiogenesis and cytoskeletal regulation and wnt signaling.

Bottom Line: Several studies have investigated the genetic alteration status of multifocal thyroid tumours, with discordant results.Our data corroborated miRNAs previously discovered in this carcinoma, and additional miRNAs linked to various processes involved in tumour growth and proliferation.The initial genetic alteration analysis indicated that pluriform PTC did not necessarily evolve from classic PTC progenitor foci.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Histopathology, Trinity College, Dublin, Ireland. ahernesi@tcd.ie

ABSTRACT

Background: Papillary thyroid carcinoma (PTC) frequently presents as multiple tumour-foci within a single thyroid gland or pluriform, with synchronous tumours comprising different histological variants, raising questions regarding its clonality. Among the genetic aberrations described in PTC, the BRAF V600E mutation and ret/PTC activation occur most commonly. Several studies have investigated the genetic alteration status of multifocal thyroid tumours, with discordant results. To address the question of clonality this study examined disparate geographical and morphological areas from a single PTC (classic PTC, insular and anaplastic foci, and tumour cells adjacent to vascular invasion and lymphocytic infiltrate) for the presence of ret/PTC 1 or BRAF mutations. Moreover, we wanted to investigate the consistency of miRNA signatures within disparate areas of a tumour, and geographical data was further correlated with expression profiles of 330 different miRNAs. Putative miRNA gene targets were predicted for differentially regulated miRNAs and immunohistochemistry was performed on tissue sections in an effort to investigate phenotypic variations in microvascular density (MVD), and cytokeratin and p53 protein expression levels.

Results: All of the morphological areas proved negative for ret/PTC 1 rearrangement. Two distinct foci with classic morphology harboured the BRAF mutation. All other regions, including the insular and anaplastic areas were negative for the mutation. MiRNA profiles were found to distinguish tumours containing the BRAF mutation from the other tumour types, and to differentiate between the more aggressive insular & anaplastic tumours, and the classic variant. Our data corroborated miRNAs previously discovered in this carcinoma, and additional miRNAs linked to various processes involved in tumour growth and proliferation.

Conclusion: The initial genetic alteration analysis indicated that pluriform PTC did not necessarily evolve from classic PTC progenitor foci. Analysis of miRNA profiles however provided an interesting variation on the clonality question. While hierarchical clustering analysis of miRNA expression supported the hypothesis that discrete areas did not evolve from clonal expansion of tumour cells, it did not exclude the possibility of independent mutational events suggesting both phenomena might occur simultaneously within a tumour to enhance cancer progression in geographical micro-environments within a tumour.

Show MeSH
Related in: MedlinePlus