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Profiling mTOR pathway in neuroendocrine tumors

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Abstract

The serine/threonine kinase mammalian target of rapamycin (mTOR) plays a central role in regulating critical cellular processes such as growth, proliferation, and protein synthesis. The study of cancer predisposing syndromes within which neuroendocrine tumors (NETs) may arise has furnished clues on the involvement of mTOR pathway in sporadic diseases so far. Recent comprehensive analyses have definitely shown activation of mTOR pathway in both experimental and human sporadic NETs. Upstream regulators of mTOR (PTEN and TSC2) have been found mutated in sporadic pNETs. Activation of mTOR pathways in NETs is already demonstrated by expression profiles analysis that revealed downregulation of TSC2 gene and alterations of TSC2 and PTEN protein expression in the vast majority of well-differentiated tumors. Moreover, a global microRNA expression analysis revealed the overexpression, in highly aggressive tumors, of a microRNA (miR-21) that targets PTEN reducing its expression and therefore leading to mTOR activation as well. Overall, these clues have furnished the rationale for the use of mTOR inhibitors the treatment of pNETs. With the recent approval of Everolimus (mTOR-targeted drug) for the treatment of advanced pNETs, this paradigm has been effectively translated into the clinical setting. In this review, we discuss mTOR pathway involvement in NETs, the clinical evidence supporting the use of mTOR inhibitors in cancer treatment, and the current clinical issues that remain to be elucidated to improve patient management.

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Acknowledgement

This paper was partly supported by grants from the Associazione Italiana Ricerca sul Cancro (AIRC IG-11930 and AIRC 5 per mille 12182).

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Authors and Affiliations

  1. Section of Medical Oncology, Department of Medicine, Azienda Ospedaliera Universitaria Integrata (AOUI), P.le Scuro 10, 37134, Verona, Italy

    S. Cingarlini, M. Bonomi & G. Tortora

  2. ARC-NET Research Centre and Department of Pathology and Diagnostic, Azienda Ospedaliera Universitaria Integrata (AOUI), Verona, Italy

    V. Corbo & A. Scarpa

Authors
  1. S. Cingarlini
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  2. M. Bonomi
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  3. V. Corbo
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  4. A. Scarpa
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  5. G. Tortora
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Correspondence to S. Cingarlini.

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Cingarlini, S., Bonomi, M., Corbo, V. et al. Profiling mTOR pathway in neuroendocrine tumors. Targ Oncol 7, 183–188 (2012). https://doi.org/10.1007/s11523-012-0226-9

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  • DOI: https://doi.org/10.1007/s11523-012-0226-9

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