Loss of imprinting and elevated expression of wild-type p73 in human gastric adenocarcinoma

Min J. Kang, Bum Joon Park, Do S. Byun, Jae I. Park, Hyo Jong Kim, Jae Hoon Park, Sung-Gil Chi

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Abstract

The p73 gene located at 1p36.3 encodes for a protein with significant similarity to p53. To investigate the penetrance of p73 in gastric carcinogenesis, we analyzed the expression, allelotype, and mutation of p73 in five cell lines and 75 tissues. Although extremely low levels of p73 expression were observed in all noncancerous gastric tissues and four of five cell lines, a significant elevation of p73 was detected in 37 of 39 (94.9%) carcinoma tissues. Furthermore, a tumor-specific increase of p73 was identified in 14 of 16 (87.5%) matched sets. Allelotyping analysis using a StyI or BanI polymorphism revealed that 5 of 21 (23.8%) informative carcinomas, but none of 19 noncancerous cases, express p73 biallelically, suggesting the transcriptional activation of a silent allele in a subset of cancers. Whereas the transcription of an active allele was markedly induced by serum starvation or clump formation of the cells, treatment with 5-aza- 2'deoxycytidine activated a silent allele with a subsequent up-regulation of an active allele, supporting the genomic imprinting and autoregulation of the gene. Allelic deletion or mutation of the gene was not found, and no association of p73 expression with the mutational status of p53 or expression of p21(Waf1) was recognized. Taken together, this study argues that p73 is not a target of genetic alteration in gastric carcinogenesis and suggests that overexpression of p73 might be triggered by physiological stresses accompanied with outgrowth of tumors, such as hypoxia or nutrient deprivation.

Original languageEnglish
Pages (from-to)1767-1771
Number of pages5
JournalClinical Cancer Research
Volume6
Issue number5
Publication statusPublished - 2000 May 1
Externally publishedYes

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ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Kang, M. J., Park, B. J., Byun, D. S., Park, J. I., Kim, H. J., Park, J. H., & Chi, S-G. (2000). Loss of imprinting and elevated expression of wild-type p73 in human gastric adenocarcinoma. Clinical Cancer Research, 6(5), 1767-1771.