Expression of O6-methylguanine DNA methyltransferase (MGMT) and immunohistochemical analysis of 12 pineal parenchymal tumors

Hiromi Kanno, Hiroshi Nishihara, Mitsuteru Oikawa, Yoshimaru Ozaki, Junichi Murata, Yutaka Sawamura, Masahito Kato, Kanako Kubota, Mishie Tanino, Taichi Kimura, Kazuo Nagashima, Tamio Itoh, Shinya Tanaka

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Pineal parenchymal tumors (PPTs) are rare neoplasms which occupy less than 1% of primary CNS tumors. Because of their rare incidence, previous reports on PPTs are limited in number and the useful molecular markers for deciding histological grading and even selecting chemotherapy are undetermined. In this study, we conducted immunohistochemical analysis of 12 PPT specimens, especially for expression of O6-methylguanine DNA methyltransferase (MGMT) to assess whether temozolomide (TMZ) could serve as a possible alternative therapy for PPTs. We analyzed 12 PPTs, consisting of three pineocytomas, six PPTs of intermediate differentiation (PPTIDs), and three pineoblastomas. Immunohistochemical analysis was performed using antibodies against MGMT, synaptophysin, neurofilament protein (NF), p53, and neuronal nuclear antigen (NeuN). Immunohistochemically, 11 out of 12 cases were positive for MGMT. The mean MIB-1 labeling index was less than 1% in pineocytoma, 3.5% in PPTID, and 10.5% in pineoblastoma. All 12 cases were positive for synaptophysin and 11 cases, except one PPTID case, showed positive for NF. Nuclear staining of NeuN was negative in all cases although cytoplasmic staining of NeuN was observed in five cases. No case was positive for p53. Eleven out of 12 cases of PPTs demonstrated MGMT expression, suggesting chemoresistancy to TMZ treatment. This is the first report showing MGMT expression in PPTs. In addition, MIB-1 labeling index correlated with WHO grade, although the immunoreactivity of synaptophysin, NF, NeuN and p53 did not correlate with the histological grade.

Original languageEnglish
Pages (from-to)647-653
Number of pages7
Issue number6
Publication statusPublished - 2012 Dec
Externally publishedYes


  • Immunohistochemistry
  • MGMT
  • MIB-1
  • Pinealoma
  • Temozolomide

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Clinical Neurology


Dive into the research topics of 'Expression of O6-methylguanine DNA methyltransferase (MGMT) and immunohistochemical analysis of 12 pineal parenchymal tumors'. Together they form a unique fingerprint.

Cite this