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Activation of the mTOR signaling pathway in renal clear cell carcinoma

Victoria A Robb1, Magdalena Karbowniczek, Andres J Klein-Szanto

  • 1Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.

The Journal of Urology
|December 13, 2006
PubMed
Abstract

Insights

The mechanistic target of rapamycin (mTOR)/p70S6 kinase pathway is activated in most clear cell renal cell carcinomas. Inhibiting this pathway with rapamycin reduced cancer cell proliferation, suggesting therapeutic potential.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Signaling

Background:

  • The mechanistic target of rapamycin (mTOR) pathway regulates cell growth and proliferation.
  • Dysregulation of the mTOR pathway is implicated in various cancers, including renal cell carcinoma (RCC).

Purpose of the Study:

  • To determine the frequency of mTOR/p70S6 kinase pathway activation in clear cell renal cell carcinoma (ccRCC).
  • To investigate the potential of mTOR inhibitors as a therapeutic strategy for ccRCC.

Main Methods:

  • Immunohistochemical staining for phospho-S6 and phospho-mTOR in 29 ccRCC tissue samples.
  • Mutational analysis of Rheb and RhebL1 in ccRCC tumors with pathway activation.
  • Assessment of mTOR activation and rapamycin's effect on proliferation in three ccRCC cell lines.

Main Results:

  • 59% of ccRCC samples (17/29) showed activation of the mTOR/p70S6 kinase pathway.
  • No mutations in Rheb or RhebL1 were identified as the cause of pathway activation.
  • Rapamycin significantly inhibited S6 phosphorylation and proliferation in ccRCC cell lines.

Conclusions:

  • The mTOR/p70S6 kinase pathway is frequently activated in ccRCC.
  • mTOR inhibition, using agents like rapamycin, demonstrates therapeutic potential for ccRCC treatment.

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