p16 INK4, pRB, p53 and cyclin D1 expression and hypermethylation of CDKN2 gene in thymoma and thymic carcinoma

Hirohisa Hirabayashi, Yoshitaka Fujii, Masahiro Sakaguchi, Hisaichi Tanaka, Hyung Eun Yoon, Yosuke Komoto, Masahiro Inoue, Shinichiro Miyoshi, Hikaru Matsuda

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55 Citations (Scopus)

Abstract

There have been few reports on genetic alterations in thymomas. To investigate the expression of p16INK4A, RB, p53 and cyclin D1 in thymomas, we first examined 36 thymomas (non-invasive type, 16 cases; invasive type, 20 cases) and 3 thymic carcinomas, using immunohistochemistry. Abnormal expression of p16INK4A, RB, p53 and cyclin D1 was observed in 18, 8, 10 and 7 cases, respectively. Only a subgroup of invasive thymomas and thymic carcinomas showed an inverse correlation between p16INK4A and RB expression. Subsequently, we examined the 36 thymomas and 4 thymic carcinomas for mutations in p53 and CDKN2 genes, using PCR-SSCP and direct-sequencing analyses. No mutation of these genes was detected in the thymomas and thymic carcinomas examined. A polymorphism in the 3′ untranslated region of exon 3 of CDKN2 was detected in 5 cases of thymoma. We searched for hypermethylation in the promoter region of CDKN2, observing it in 4 thymomas and 1 thymic carcinoma. Our data suggest that, unlike other more common cancers, alteration of the p53 gene may not play a significant role in the tumorigenesis of thymoma. However, inactivation of p16INK4A and RB may play a role in the progression of thymoma and thymic carcinoma.

Original languageEnglish
Pages (from-to)639-644
Number of pages6
JournalInternational Journal of Cancer
Volume73
Issue number5
Publication statusPublished - Nov 27 1997

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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    Hirabayashi, H., Fujii, Y., Sakaguchi, M., Tanaka, H., Yoon, H. E., Komoto, Y., Inoue, M., Miyoshi, S., & Matsuda, H. (1997). p16 INK4, pRB, p53 and cyclin D1 expression and hypermethylation of CDKN2 gene in thymoma and thymic carcinoma. International Journal of Cancer, 73(5), 639-644.