Expression of the p16INK4A/Cdkn2a gene is prevalently downregulated in human pheochromocytoma tumor specimens

Peter Muscarella, Mark Bloomston, Alexander R. Brewer, Anjali Mahajan, Wendy L. Frankel, E. Christopher Ellison, William B. Farrar, Christopher M. Weghorst, Junan Li

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

A number of hereditary syndromes have been found to be associated with pheochromocytoma development, but there is a paucity of data regarding secondary molecular events, such as downregulation of the p16INK4A/Cdkn2a gene (hereafter p16), contributing to pheochromocytoma tumorigenesis. Using tissue microarray and immunohistochemistry, we evaluated the expression of p16 in 31 pheochromocytoma tumor specimens. Our results showed that the p16 gene was expressed at low level or even not expressed in all but one specimens [30/31 (96.8%)], indicative of the prevalence of p16 downregulation in pheochromocytomas. In contrast, high expression of p16 was observed in the majority of control "normal" specimens [5/ 7 (71.6%)]. To further investigate the molecular mechanisms underlying p16 downregulation in pheochromocytomas, we used quantitative real-time PCR, methylation-specific PCR, and direct DNA sequencing to analyze these specimens for potential genetic alterations of the p16 gene. Deletions and aberrant CpG methylation of p16 were identified in 9 (29.0%) and 11 (35.5%) specimens, respectively, while one specimen harbored a point mutation, Ala → Pro at residue 20 of P16, and this mutation led to an eightfold decrease in the CDK4-inhibitory activity of P16. The overall frequency of p16 genetic alterations is 67.7%. Taken together, our results demonstrate that reduced expression of p16 is a common event in human pheochromocytomas, and the primary cause for such downregulation is inactivating genetic abnormalities in the p16 gene.

Original languageEnglish (US)
Pages (from-to)207-216
Number of pages10
JournalGene Expression
Volume14
Issue number4
DOIs
StatePublished - 2008
Externally publishedYes

Fingerprint

p16 Genes
Pheochromocytoma
Down-Regulation
Neoplasms
Methylation
DNA Sequence Analysis
Point Mutation
Real-Time Polymerase Chain Reaction
Carcinogenesis
Immunohistochemistry
Polymerase Chain Reaction
Mutation

Keywords

  • Expression downregulation
  • Genetic alterations
  • p16
  • Pheochromocytomas

ASJC Scopus subject areas

  • Medicine(all)
  • Molecular Biology
  • Genetics

Cite this

Expression of the p16INK4A/Cdkn2a gene is prevalently downregulated in human pheochromocytoma tumor specimens. / Muscarella, Peter; Bloomston, Mark; Brewer, Alexander R.; Mahajan, Anjali; Frankel, Wendy L.; Ellison, E. Christopher; Farrar, William B.; Weghorst, Christopher M.; Li, Junan.

In: Gene Expression, Vol. 14, No. 4, 2008, p. 207-216.

Research output: Contribution to journalArticle

Muscarella, P, Bloomston, M, Brewer, AR, Mahajan, A, Frankel, WL, Ellison, EC, Farrar, WB, Weghorst, CM & Li, J 2008, 'Expression of the p16INK4A/Cdkn2a gene is prevalently downregulated in human pheochromocytoma tumor specimens', Gene Expression, vol. 14, no. 4, pp. 207-216. https://doi.org/10.3727/105221608786883825
Muscarella, Peter ; Bloomston, Mark ; Brewer, Alexander R. ; Mahajan, Anjali ; Frankel, Wendy L. ; Ellison, E. Christopher ; Farrar, William B. ; Weghorst, Christopher M. ; Li, Junan. / Expression of the p16INK4A/Cdkn2a gene is prevalently downregulated in human pheochromocytoma tumor specimens. In: Gene Expression. 2008 ; Vol. 14, No. 4. pp. 207-216.
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AU - Bloomston, Mark

AU - Brewer, Alexander R.

AU - Mahajan, Anjali

AU - Frankel, Wendy L.

AU - Ellison, E. Christopher

AU - Farrar, William B.

AU - Weghorst, Christopher M.

AU - Li, Junan

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AB - A number of hereditary syndromes have been found to be associated with pheochromocytoma development, but there is a paucity of data regarding secondary molecular events, such as downregulation of the p16INK4A/Cdkn2a gene (hereafter p16), contributing to pheochromocytoma tumorigenesis. Using tissue microarray and immunohistochemistry, we evaluated the expression of p16 in 31 pheochromocytoma tumor specimens. Our results showed that the p16 gene was expressed at low level or even not expressed in all but one specimens [30/31 (96.8%)], indicative of the prevalence of p16 downregulation in pheochromocytomas. In contrast, high expression of p16 was observed in the majority of control "normal" specimens [5/ 7 (71.6%)]. To further investigate the molecular mechanisms underlying p16 downregulation in pheochromocytomas, we used quantitative real-time PCR, methylation-specific PCR, and direct DNA sequencing to analyze these specimens for potential genetic alterations of the p16 gene. Deletions and aberrant CpG methylation of p16 were identified in 9 (29.0%) and 11 (35.5%) specimens, respectively, while one specimen harbored a point mutation, Ala → Pro at residue 20 of P16, and this mutation led to an eightfold decrease in the CDK4-inhibitory activity of P16. The overall frequency of p16 genetic alterations is 67.7%. Taken together, our results demonstrate that reduced expression of p16 is a common event in human pheochromocytomas, and the primary cause for such downregulation is inactivating genetic abnormalities in the p16 gene.

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