Activation of Akt as a mechanism for tumor immune evasion

Kyung Hee Noh, Tae Heung Kang, Jin Hee Kim, Sara I. Pai, Ken Y. Lin, Chien Fu Hung, T. C. Wu, Tae Woo Kim

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Immune evasion is an important reason why the immune system cannot control tumor growth. To elucidate the mechanism for tumor immune evasion, we generated an immune-resistant human papillomavirus type 16 (HPV-16) E7-expressing tumor cell line by subjecting a susceptible tumor cell line to multiple rounds of in vivo immune selection with an E7-specific vaccine. Comparison of parental and immune-resistant tumors revealed that Akt is highly activated in the immune-resistant tumors. Retroviral transfer of a constitutively active form of Akt into the parental tumor significantly increased its resistance against E7-specific CD8+ T-cell mediated apoptosis. The observed resistance against apoptosis was found to be associated with the upregulation of antiapoptotic molecules. We also observed that intratumoral injection of an Akt inhibitor enhanced the therapeutic efficacy of E7-specific vaccine or E7-specific CD8+ T-cell adoptive transfer against the immune-resistant tumors. Thus, our data indicate that the activation of PI3K/Akt pathway represents a new mechanism of immune escape and has important implications for the development of a novel strategy in cancer immunotherapy against immune-resistant tumor cells.

Original languageEnglish (US)
Pages (from-to)439-447
Number of pages9
JournalMolecular Therapy
Issue number3
StatePublished - 2009

ASJC Scopus subject areas

  • Molecular Medicine
  • Molecular Biology
  • Genetics
  • Pharmacology
  • Drug Discovery


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