SAV1 represses the development of human colorectal cancer by regulating the Akt-mTOR pathway in a YAP-dependent manner

Cell Prolif. 2017 Aug;50(4):e12351. doi: 10.1111/cpr.12351. Epub 2017 Jun 15.

Abstract

Objectives: SAV1 is a human homologue of Salvador that contains two protein-protein interaction modules known as WW domains and acts as a scaffolding protein. SAV1 participates in the development of diverse types of cancer. We aimed to investigate the role of SAV1 in human colorectal cancer.

Materials and methods: Human colorectal cancer samples were used to study the expression of SAV1 and YAP. Loss-of-function and gain-of-function strategies were used to study the effects of SAV1 on colorectal cancer cell growth. Rapamycin was used to treat cells and mice to investigate the effect of mTOR signalling.

Results: SAV1 represses the development of colorectal cancer by inhibiting the Akt-mTOR signalling in a YAP-dependent manner. The mRNA and protein levels of SAV1 are down-regulated in human colorectal cancer tissues compared with adjacent non-cancer tissues. SAV1 knockdown promotes the growth of colorectal cancer cells in vitro and in vivo, whereas SAV1 overexpression leads to opposing results. SAV1 represses the activation of the Akt-mTOR signalling, and rapamycin treatment blunts the effects of SAV1 on in vitro and in vivo growth of colorectal cancer cells. Finally, we show that SAV1 promotes the phosphorylation and inactivation of YAP, which contributes to the effect of SAV1 on Akt-mTOR signalling pathway.

Conclusions: SAV1 is a repressor during the development of human colorectal cancer by inhibiting the YAP-Akt-mTOR signalling pathway.

MeSH terms

  • Adult
  • Aged
  • Animals
  • Cell Cycle Proteins / antagonists & inhibitors
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Colorectal Neoplasms / metabolism
  • Colorectal Neoplasms / pathology*
  • Down-Regulation
  • Female
  • Humans
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Middle Aged
  • Nuclear Proteins / antagonists & inhibitors
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism*
  • RNA Interference
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / metabolism
  • Signal Transduction / drug effects
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases / metabolism*
  • Transcription Factors / antagonists & inhibitors
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transplantation, Heterologous

Substances

  • Cell Cycle Proteins
  • Nuclear Proteins
  • RNA, Messenger
  • RNA, Small Interfering
  • SAV1 protein, human
  • Transcription Factors
  • YY1AP1 protein, human
  • MTOR protein, human
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Sirolimus