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Activation of mTORC1 signaling pathway in AIDS-related lymphomas

Mouna El-Salem1, Puthiyaveettil N Raghunath, Michal Marzec

  • 1University of Pennsylvania Medical Center, Department of Pathology and Laboratory Medicine, 3400 Spruce Street, 7.106 Founders Pavilion, Philadelphia, PA 19104, USA.

The American Journal of Pathology
|July 18, 2009
PubMed

Insights

The mammalian target of rapamycin (mTORC)1 pathway is activated in AIDS-related lymphomas and HIV-associated lymphadenopathy. Inhibiting mTORC1 or its upstream activators may offer new treatments for these lymphomas.

Area of Science:

  • Oncology
  • Immunology
  • Molecular Biology

Background:

  • The mammalian target of rapamycin (mTORC)1 pathway plays a crucial role in cell growth and proliferation.
  • Dysregulation of mTORC1 signaling is implicated in various cancers, including lymphomas.
  • AIDS-related lymphomas are aggressive malignancies often associated with human immunodeficiency virus (HIV) infection.

Purpose of the Study:

  • To investigate the activation status of the mTORC1 pathway in AIDS-related lymphomas.
  • To explore the role of mTORC1 in HIV-associated lymphadenopathy.
  • To identify potential therapeutic targets by examining upstream activators of mTORC1 in lymphoma cell lines.

Main Methods:

  • Immunohistochemistry was used to detect activated phosphoserine residues of S6rp and 4E-binding protein 1.
  • Analysis included cases of non-Hodgkin lymphoma, classic Hodgkin lymphoma, and HIV-associated lymphadenopathy.
  • In vitro studies utilized B-cell lines representing various lymphoma subtypes to test the effects of pathway inhibitors.

Main Results:

  • mTORC1 pathway activation was identified in 29 cases of AIDS-related lymphoma across diverse histological subtypes.
  • Activated mTORC1 was also observed in hyperplastic follicles of HIV-associated lymphadenopathy, but not in involuted follicles.
  • Inhibition of Syk, MEK, and phosphoinositide 3 kinases, particularly in combination, suppressed mTORC1 activation in lymphoma cell lines.

Conclusions:

  • mTORC1 activation is a common feature in transformed lymphocytes, regardless of their reactive or malignant phenotype.
  • These findings suggest that AIDS-related lymphomas and similar B-cell lymphomas may respond to therapies targeting mTORC1.
  • Inhibitors of mTORC1 or its upstream activators represent a promising therapeutic strategy for AIDS-related lymphomas.

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