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Updated: Jul 24, 2026

In vitro Organoid Culture of Primary Mouse Colon Tumors
07:33

In vitro Organoid Culture of Primary Mouse Colon Tumors

Published on: May 17, 2013

Cyclic GMP-dependent protein kinase activation and induction by exisulind and CP461 in colon tumor cells

L Liu1, H Li, T Underwood

  • 1Cell Pathways, Inc., Horsham, Pennsylvania 19044, USA. lliu@cellpathways.com

The Journal of Pharmacology and Experimental Therapeutics
|October 17, 2001
PubMed

Insights

Exisulind and its analogs activate cyclic guanosine monophosphate-dependent protein kinase (PKG) in colon tumor cells, leading to increased beta-catenin phosphorylation and apoptosis. This suggests PKG activation is key for exisulind

Area of Science:

  • Oncology
  • Molecular Biology
  • Pharmacology

Background:

  • Exisulind and analogs are pro-apoptotic drugs targeting cGMP phosphodiesterase.
  • These drugs increase cyclic guanosine monophosphate (cGMP) levels in colon tumor cells.
  • The role of cGMP-dependent protein kinase (PKG) in colon tumor cell apoptosis is under investigation.

Purpose of the Study:

  • To investigate the activation and induction of PKG by exisulind and analogs.
  • To determine if PKG activation mediates apoptosis in colon tumor cells.
  • To explore the downstream effects of PKG activation, including beta-catenin phosphorylation.

Main Methods:

  • Treatment of colon tumor cell lines (SW480, HT29, T84, HCT116) with exisulind, CP461, YC-1, and guanylin.
  • Measurement of PKG activity in cell supernatants and protein expression.
  • In vitro phosphorylation assays using purified PKG and beta-catenin.
  • Analysis of beta-catenin phosphorylation in drug-treated cells.

Main Results:

  • Exisulind and analogs sustained increased cGMP levels and activated PKG in a dose-dependent manner.
  • PKG activation was observed across multiple colon tumor cell lines.
  • Exisulind treatment led to increased PKG Ibeta protein expression and enhanced beta-catenin phosphorylation.
  • Guanylyl cyclase activators also increased PKG activity and induced apoptosis.

Conclusions:

  • Exisulind and analogs activate and induce PKG in colon tumor cells.
  • PKG activation, leading to beta-catenin phosphorylation, is a key mechanism for exisulind-induced apoptosis.
  • These findings highlight PKG as a therapeutic target for colon cancer treatment.

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