The
mammalian target of rapamycin (mTOR) signaling pathway has emerged as a major effector of cell growth and proliferation, and is an attractive target for
cancer therapy. However, the association between mTOR pathway and the
malignancy grade of human
gliomas has not been thoroughly investigated.
Tumor tissues from 87 Chinese patients (49 males, average age of 51.7 ± 13.0 years, range 15-78) with
glioma were prospectively collected. The expression of three key
proteins of the mTOR pathway, pAKT, pmTOR and p-p70S6
kinase (p-p70S6K) was measured by semi-quantitative immunohistochemical techniques. Grade I-II, III and IV
glioma was pathologically identified in 27 (31.0%), 24 (27.6%) and 36 (41.4%) patients, respectively. Of the 87 patients, pAKT, pmTOR and p-p70S6K were found in 63 (72.4%), 65 (74.7%), and 63 (72.4%) patients, respectively. The expression of all three pAKT, pmTOR and p-p70S6K
proteins was found in 42 (48.3%) patients, while only one or two of the three
proteins were found in the remaining patients (51.7%). The percentage of patients with very strong expression of pAKT, pmTOR and p-p70S6K in grade IV
glioma was 13 (36.1%), 16 (44.4%) and 15 (41.7%), respectively, which was greater than in grade I or II
tumors (0-3.7%, P < 0.01). In conclusion, expression of mTOR pathway
proteins pAKT, pmTOR and p-p70S6K can be found in human
glioma of all
malignancy grades. However, higher levels of these
proteins were associated with advanced
malignancy grades of the
tumor.