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Updated: Jul 18, 2026

Development and Application of Rapamycin-regulated Tyrosine Phosphatases
Published on: September 6, 2024
Phosphorylation of ribosomal p70 S6 kinase and rapamycin sensitivity in human colorectal cancer
Hiroaki Nozawa1, Toshiaki Watanabe, Hirokazu Nagawa
1Department of Surgical Oncology, University of Tokyo, 7-3-1 Hongo, Bunkyu-ku, Tokyo 113-8655, Japan. hiroanozawa-gi@umin.ac.jp <hiroanozawa-gi@umin.ac.jp>
Abstract:
We investigated the Akt-mTOR pathway and effects of rapamycin using human colorectal cancer cell lines. LoVo and CaRI reduced proliferative activity in response to rapamycin in a dose-dependent manner. The phosphorylation of Akt and p70 S6K was prominent in these cells. Rapamycin quickly downregulated phospho-S6K but not phospho-Akt. Therefore, phospho-S6K is considered a good indicator of the activated Akt-mTOR pathway as well as rapamycin sensitivity in colorectal cancer cells. By immunohistochemical study, nearly 40% of adenomas and carcinomas of the colorectum exhibited either partial or whole positive staining for phospho-S6K, suggestive of rapamycin-sensitive lesions.
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