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A role for the transcription factor HEY1 in glioblastoma.

Hulleman E, Quarto M, Vernell R, Masserdotti G, Colli E, Kros JM, Levi D, Gaetani P, Tunici P, Finocchiaro G, Baena RR, Capra M, Helin K - J. Cell. Mol. Med. (2008)

Bottom Line: In addition, we show by chromatin immunoprecipitations, luciferase assays and Northern blot experiments that HEY1 is a bona fide target of the E2F family of transcription factors, connecting the Ras and Notch signalling pathways.Finally, we show that ectopic expression of HEY1 induces cell proliferation in neural stem cells, while depletion of HEY1 by RNA interference reduces proliferation of glioblastoma cells in tissue culture.Moreover, HEY1 may represent a molecular marker to distinguish GBM patients with a longer survival prognosis from those at high risk.

View Article: PubMed Central - PubMed

Affiliation: European Institute of Oncology, Via Ripamonti, Milan, Italy.

ABSTRACT
Abstract Glioblastoma multiforme (GBM), the highest-grade glioma, is the most frequent tumour of the brain with a very poor prognosis and limited therapeutic options. Although little is known about the molecular mechanisms that underlie glioblastoma formation, a number of signal transduction routes, such as the Notch and Ras signalling pathways, seem to play an important role in the formation of GBM. In the present study, we show by in situ hybridization on primary tumour material that the transcription factor HEY1, a target of the Notch signalling pathway, is specifically up-regulated in glioma and that expression of HEY1 in GBM correlates with tumour-grade and survival. In addition, we show by chromatin immunoprecipitations, luciferase assays and Northern blot experiments that HEY1 is a bona fide target of the E2F family of transcription factors, connecting the Ras and Notch signalling pathways. Finally, we show that ectopic expression of HEY1 induces cell proliferation in neural stem cells, while depletion of HEY1 by RNA interference reduces proliferation of glioblastoma cells in tissue culture. Together, these data imply a role for HEY1 in the progression of GBM, and therefore we propose that HEY1 may be a therapeutic target for glioblastoma patients. Moreover, HEY1 may represent a molecular marker to distinguish GBM patients with a longer survival prognosis from those at high risk.

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HEY1 is specifically expressed in glioblastoma. (A) Representative images of HEY1 expression as detected by in situ hybridization-tissue microarray (ISH-TMA); in each pair, the bright field haematoxylin and eosin counterstaining for morphologic evaluation (upper panel, 100× magnification) and the concomitant dark field HEY1 ISH signal (silver grains, lower panel) are shown. Transcripts appear as bright dots; the signal observed in normal brain is considered to be background staining. (B) Summary of HEY1 expression on glioma specific TMAs as determined by in situ hybridization; the number of HEY1 positive tumours is shown in relationship to tumour grade.
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fig02: HEY1 is specifically expressed in glioblastoma. (A) Representative images of HEY1 expression as detected by in situ hybridization-tissue microarray (ISH-TMA); in each pair, the bright field haematoxylin and eosin counterstaining for morphologic evaluation (upper panel, 100× magnification) and the concomitant dark field HEY1 ISH signal (silver grains, lower panel) are shown. Transcripts appear as bright dots; the signal observed in normal brain is considered to be background staining. (B) Summary of HEY1 expression on glioma specific TMAs as determined by in situ hybridization; the number of HEY1 positive tumours is shown in relationship to tumour grade.

Mentions: Since the pRB/E2F signal transduction pathway is frequently deregulated in different kinds of tumours and accumulating results indicate that deregulated Notch activity is also involved in the genesis of human cancers [46, 47], we set out to determine the expression of HEY1 in primary human tumours. Therefore, primary human tumour material, representing 10 different types of tumours was spotted on tissue micro arrays (TMAs) – together with their normal counterparts – and screened by ISH to determine HEY1 mRNA expression. As shown in Table 1, expression of HEY1 was not detected in most of the normal and tumour tissues analysed, but HEY1 was highly expressed in several melanomas and glioblastomas. Of the 13 glioblastoma samples present on the TMA, one tumour showed no detectable HEY1 mRNA expression, seven samples expressed low and five samples very high amounts of HEY1 mRNA. Similarly, HEY1 was found to be highly expressed in about 20% of melanoma samples tested (3/15). The high expression of HEY1 in glioblastoma was particularly interesting, since several Hairy/E(spl) family members have been shown to be involved in neurogenesis [48–50]. Moreover, recent findings suggest that Notch signalling plays an essential role in the formation of brain tumours and the self-renewal of NSCs [51–54]. Therefore, 170 additional brain tumour samples – including the fullrange of malignancy grades from low-grade gliomas to GBM – were examined for HEY1 expression using ISH. Strikingly, HEY1 expression was detected almost exclusively in glioma, while no expression was found in other brain tumours or in normal brain tissue (Fig. 2A, Table 2). Since, in these cases, no normal counterparts of the same patients were available, other brain biopsies were used as a negative control (haemorrhage).


A role for the transcription factor HEY1 in glioblastoma.

Hulleman E, Quarto M, Vernell R, Masserdotti G, Colli E, Kros JM, Levi D, Gaetani P, Tunici P, Finocchiaro G, Baena RR, Capra M, Helin K - J. Cell. Mol. Med. (2008)

HEY1 is specifically expressed in glioblastoma. (A) Representative images of HEY1 expression as detected by in situ hybridization-tissue microarray (ISH-TMA); in each pair, the bright field haematoxylin and eosin counterstaining for morphologic evaluation (upper panel, 100× magnification) and the concomitant dark field HEY1 ISH signal (silver grains, lower panel) are shown. Transcripts appear as bright dots; the signal observed in normal brain is considered to be background staining. (B) Summary of HEY1 expression on glioma specific TMAs as determined by in situ hybridization; the number of HEY1 positive tumours is shown in relationship to tumour grade.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3823042&req=5

fig02: HEY1 is specifically expressed in glioblastoma. (A) Representative images of HEY1 expression as detected by in situ hybridization-tissue microarray (ISH-TMA); in each pair, the bright field haematoxylin and eosin counterstaining for morphologic evaluation (upper panel, 100× magnification) and the concomitant dark field HEY1 ISH signal (silver grains, lower panel) are shown. Transcripts appear as bright dots; the signal observed in normal brain is considered to be background staining. (B) Summary of HEY1 expression on glioma specific TMAs as determined by in situ hybridization; the number of HEY1 positive tumours is shown in relationship to tumour grade.
Mentions: Since the pRB/E2F signal transduction pathway is frequently deregulated in different kinds of tumours and accumulating results indicate that deregulated Notch activity is also involved in the genesis of human cancers [46, 47], we set out to determine the expression of HEY1 in primary human tumours. Therefore, primary human tumour material, representing 10 different types of tumours was spotted on tissue micro arrays (TMAs) – together with their normal counterparts – and screened by ISH to determine HEY1 mRNA expression. As shown in Table 1, expression of HEY1 was not detected in most of the normal and tumour tissues analysed, but HEY1 was highly expressed in several melanomas and glioblastomas. Of the 13 glioblastoma samples present on the TMA, one tumour showed no detectable HEY1 mRNA expression, seven samples expressed low and five samples very high amounts of HEY1 mRNA. Similarly, HEY1 was found to be highly expressed in about 20% of melanoma samples tested (3/15). The high expression of HEY1 in glioblastoma was particularly interesting, since several Hairy/E(spl) family members have been shown to be involved in neurogenesis [48–50]. Moreover, recent findings suggest that Notch signalling plays an essential role in the formation of brain tumours and the self-renewal of NSCs [51–54]. Therefore, 170 additional brain tumour samples – including the fullrange of malignancy grades from low-grade gliomas to GBM – were examined for HEY1 expression using ISH. Strikingly, HEY1 expression was detected almost exclusively in glioma, while no expression was found in other brain tumours or in normal brain tissue (Fig. 2A, Table 2). Since, in these cases, no normal counterparts of the same patients were available, other brain biopsies were used as a negative control (haemorrhage).

Bottom Line: In addition, we show by chromatin immunoprecipitations, luciferase assays and Northern blot experiments that HEY1 is a bona fide target of the E2F family of transcription factors, connecting the Ras and Notch signalling pathways.Finally, we show that ectopic expression of HEY1 induces cell proliferation in neural stem cells, while depletion of HEY1 by RNA interference reduces proliferation of glioblastoma cells in tissue culture.Moreover, HEY1 may represent a molecular marker to distinguish GBM patients with a longer survival prognosis from those at high risk.

View Article: PubMed Central - PubMed

Affiliation: European Institute of Oncology, Via Ripamonti, Milan, Italy.

ABSTRACT
Abstract Glioblastoma multiforme (GBM), the highest-grade glioma, is the most frequent tumour of the brain with a very poor prognosis and limited therapeutic options. Although little is known about the molecular mechanisms that underlie glioblastoma formation, a number of signal transduction routes, such as the Notch and Ras signalling pathways, seem to play an important role in the formation of GBM. In the present study, we show by in situ hybridization on primary tumour material that the transcription factor HEY1, a target of the Notch signalling pathway, is specifically up-regulated in glioma and that expression of HEY1 in GBM correlates with tumour-grade and survival. In addition, we show by chromatin immunoprecipitations, luciferase assays and Northern blot experiments that HEY1 is a bona fide target of the E2F family of transcription factors, connecting the Ras and Notch signalling pathways. Finally, we show that ectopic expression of HEY1 induces cell proliferation in neural stem cells, while depletion of HEY1 by RNA interference reduces proliferation of glioblastoma cells in tissue culture. Together, these data imply a role for HEY1 in the progression of GBM, and therefore we propose that HEY1 may be a therapeutic target for glioblastoma patients. Moreover, HEY1 may represent a molecular marker to distinguish GBM patients with a longer survival prognosis from those at high risk.

Show MeSH
Related in: MedlinePlus