The mammalian target of rapamycin pathway is widely activated without PTEN deletion in renal cell carcinoma metastases

Tamer Abou Youssif, Mona Alam Fahmy, Ismael Herve Koumakpayi, Fernanda Ayala, Saeeda Al Marzooqi, Guangyong Chen, Pheroze Tamboli, Jeremy Squire, Simon Tanguay, Kanishka Sircar

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)


Background: Inhibitors of the mammalian target of rapamycin (mTOR) are emerging as promising therapies for metastatic renal cell carcinoma (RCC). Because rational treatment strategies require understanding the activation status of the underlying signaling pathway being targeted at the desired stage of disease, the authors examined the activation status of different components of the mTOR pathway in RCC metastases and matched primary tumors. Methods: The authors immunostained metastatic RCC samples from 132 patients and a subset of 25 matched primary RCCs with antibodies against phosphatidylinositol 3â-kinase, PTEN, phospho-Akt, phospho-mTOR, and p70S6. PTEN genomic status was assessed by fluorescent in situ hybridization. Marker expression was correlated to clinicopathologic variables and to survival. Results: The mTOR pathway showed widespread activation in RCC metastases of various sites with strong correlation between different components of this signaling cascade (P<.0001), but without significant PTEN genomic deletion. Only cytoplasmic phospho-mTOR showed independent prognostic significance (P =.029) and fidelity between primary RCCs and their matched metastases (P =.004). Conclusions: Activation of various components of the mTOR signaling pathway in metastatic RCC lesions across various tumor histologies, nuclear grades, and metastatic sites suggests the potential for vertical blockade of multiple steps of this pathway. Patient selection may be improved by mTOR immunostaining of primary RCC.

Original languageEnglish
Pages (from-to)290-300
Number of pages11
Issue number2
Publication statusPublished - Jan 15 2011
Externally publishedYes


  • mammalian target of rapamycin
  • metastasis
  • renal cell carcinoma
  • targeted therapy
  • temsirolimus

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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