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v-Src requires Ras signaling for the suppression of gap junctional intercellular communication

S Ito1, Y Ito, T Senga

  • 1Division of Cancer Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan.

Oncogene
|November 23, 2005
PubMed

Insights

v-Src transformation suppresses gap junctional intercellular communication (GJIC). Ras signaling, not just connexin43 phosphorylation, is crucial for this GJIC suppression in cancer cells.

Area of Science:

  • Cell Biology
  • Cancer Research
  • Signal Transduction

Background:

  • Cell transformation by v-Src oncogene inhibits gap junctional intercellular communication (GJIC).
  • Connexin43 (Cx43) tyrosine phosphorylation is implicated in GJIC suppression, but other signaling pathways remain unclear.

Purpose of the Study:

  • To investigate the role of Ras signaling in v-Src-induced suppression of GJIC.
  • To determine if Ras pathway activation is necessary for the inhibition of GJIC.

Main Methods:

  • Utilized conditional expression of dominant-negative Ras (S17N Ras) and a Ras-interacting protein mutant (mtGap1m).
  • Administered manumycin A, a Ras farnesyltransferase inhibitor, to v-Src-transformed cells.
  • Assessed GJIC recovery and levels of Cx43 tyrosine phosphorylation.

Main Results:

  • Expression of S17N Ras or mtGap1m restored GJIC in v-Src-transformed cells by reducing active Ras levels.
  • Manumycin A treatment also recovered GJIC.
  • Cx43 tyrosine phosphorylation levels remained unchanged despite GJIC restoration, indicating Ras signaling's distinct role.

Conclusions:

  • Constitutive Ras signaling activation is essential for v-Src-mediated suppression of GJIC.
  • This suppression involves both Cx43 phosphorylation and Ras pathway activation.
  • Targeting Ras signaling may offer therapeutic strategies for cancers with altered GJIC.

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