Non-immunosuppressive triazole-based small molecule induces anticancer activity against human hormone-refractory prostate cancers: The role in inhibition of PI3K/AKT/mTOR and c-Myc signaling pathways

Wohn Jenn Leu, Sharada Prasanna Swain, She Hung Chan, Jui Ling Hsu, Shih Ping Liu, Mei Ling Chan, Chia Chun Yu, Lih Ching Hsu, Yen Lin Chou, Wei Ling Chang, Duen Ren Hou, Jih Hwa Guh

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

A series of triazole-based small molecules that mimic FTY720-mediated anticancer activity but minimize its immunosuppressive effect have been produced. SPS-7 is the most effective derivative displaying higher activity than FTY720 in anti-proliferation against human hormone-refractory prostate cancer (HRPC). It induced G1 arrest of cell cycle and subsequent apoptosis in thymidine blockmediated synchronization model. The data were supported by a decrease of cyclin D1 expression, a dramatic increase of p21 expression and an associated decrease in RB phosphorylation. c-Myc overexpression replenished protein levels of cyclin D1 indicating that c-Myc was responsible for cell cycle regulation. PI3K/Akt/mTOR signaling pathways through p70S6K- and 4EBP1-mediated translational regulation are critical to cell proliferation and survival. SPS-7 significantly inhibited this translational pathway. Overexpression of Myr-Akt (constitutively active Akt) completely abolished SPS-7-induced inhibitory effect on mTOR/p70S6K/4EBP1 signaling and c-Myc protein expression, suggesting that PI3K/Akt serves as a key upstream regulator. SPS-7 also demonstrated substantial anti-tumor efficacy in an in vivo xenograft study using PC-3 mouse model. Notably, FTY720 but not SPS-7 induced a significant immunosuppressive effect as evidenced by depletion of marginal zone B cells, downregulation of sphingosine-1-phosphate receptors and a decrease in peripheral blood lymphocytes. In conclusion, the data suggest that SPS-7 is not an immunosuppressant while induces anticancer effect against HRPC through inhibition of Akt/mTOR/ p70S6K pathwaysthat down-regulate protein levels of both c-Myc and cyclin D1, leading to G1 arrest of cell cycle and subsequent apoptosis. The data also indicate the potential of SPS-7 since PI3K/Akt signalingis responsive for the genomic alterations in prostate cancer.

Original languageEnglish
Pages (from-to)76995-77009
Number of pages15
JournalOncotarget
Volume7
Issue number47
DOIs
StatePublished - 2016

Keywords

  • Autophagy
  • Myc
  • Non-immunosuppression
  • PI3K/Akt/mTOR signaling
  • Triazole-base

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