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Int J Clin Exp Pathol 2012;5(7):660-667

Original Article
Expression of phosphorylated mTOR and its regulatory protein is related to biological
behaviors of ameloblastoma

Ning Li, Ming Zhong, Ming Song

Department of Pathology, School of Stomatology, China Medical University, Shengyang, China; 2202nd Hospital of People’s Liberation Army,
Shenyang, China

Received July 1, 2012; Accepted August 1, 2012; Epub September 5, 2012; Published September 15, 2012

Abstract: The present study investigated the relationship between the expression of p-mTOR, p-4EBP1 and pp70S6K in the cytoplasm and
nucleus of ameloblastoma (AB) cells and the invasiveness of ABs. Immunohistochemistry was performed to detect the expression of p-mTOR,
p-4EBP1 and p-p70S6K in ABs and the level of these proteins in the nucleus and cytoplasm was scored. There was ectopic expression of p-
mTOR in ABs. 27 AB patients were positive for p-mTOR expression in the nucleus and 47 for p-mTOR expression in the cytoplasm. The ectopic
expression of p-4EBP-1 was also noted. 23 patients (27%) were positive for p-4EBP-1 expression in the nucleus and 55 (64.7%) for p-4EBP-1
expression in the cytoplasm. The ectopic expression of p-p70S6K was also noted. Of these patients, 33 were positive for p-p70S6K expression
in the nucleus (38.8%) and 45 for p-p70S6K expression in the cytoplasm (52.9%). Statistical analysis showed the expression of three proteins
in the nucleus of patients with recurrent cancer was markedly higher than that in those with primary cancer. The expression of p-mTOR, p-4E-
BP1 and p-p70S6K in the nucleus was related to the invasiveness of ABs. Multivariable analysis with Cox proportional hazards model showed
the p-mTOR expression had influence on AB recurrence (OR: 6.417, 95%CI: 1.428-28.824). The possibility of AB recurrence in patients with
nuclear p-mTOR expression was 6.417 folds higher than that in those with cytoplasmic p-mTOR expression. The nuclear expression of p-
mTOR, p-4E-BP1 and p-p70S6K was associated with biological behaviors (invasiveness) of ABs, and p-mTOR was an independent predictor
of AB. (ICP1207001).

Keywords: Phosphorylated mTOR, ameloblastoma, biological behavior

Address all correspondence to:
Ming Zhong, MD
Department of Pathology, School of Stomatology,
China Medical University, Shenyang, China.
Tel: 13194226788
Email: zhongming@mail.cmu.edu.cn