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Updated: Aug 15, 2026

Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death
09:18

Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death

Published on: December 27, 2016

Phosphorylation site mutated RB exerts contrasting effects on apoptotic response to different stimuli

A Masselli1, J Y J Wang

  • 1Division of Hematology-Oncology and Moores Cancer Center, Department of Medicine, UCSD School of Medicine, Health Sciences Drive, University of California San Diego, La Jolla, CA 92093, USA.

Oncogene
|October 6, 2005
PubMed

Insights

Phosphorylation site mutated retinoblastoma protein (PSM-RB) differentially affects apoptosis. PSM-RB expression attenuated doxorubicin-induced apoptosis but enhanced TNF-induced apoptosis, decoupling cell cycle arrest from apoptosis resistance.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • The retinoblastoma tumor-suppressor protein (RB) is crucial for cell cycle regulation and apoptosis.
  • Phosphorylation of RB by cyclin-dependent kinases controls cell cycle progression.
  • Mutations in RB phosphorylation sites (PSM-RB) can lead to cell cycle arrest.

Purpose of the Study:

  • To investigate the impact of inducible PSM-RB expression on apoptosis induced by doxorubicin (DOXO), staurosporine (STS), and tumor necrosis factor (TNF) in Rat-16 cells.
  • To determine if cell cycle arrest mediated by PSM-RB correlates with resistance to apoptosis.
  • To elucidate the differential roles of PSM-RB in response to various apoptotic stimuli.

Main Methods:

  • Inducible expression of PSM-RB in Rat-16 cells.
  • Treatment with three distinct death stimuli: DOXO, STS, and TNF.
  • Assessment of caspase activation as a marker of apoptosis.
  • Monitoring of cell cycle progression.

Main Results:

  • Induced PSM-RB expression attenuated DOXO-induced caspase activation, linked to G1 cell cycle arrest.
  • PSM-RB expression did not inhibit STS-induced caspase activation, despite potential for RB-dependent G1 arrest.
  • PSM-RB expression unexpectedly promoted TNF-induced apoptosis in cells that typically undergo necrosis.

Conclusions:

  • PSM-RB exhibits context-dependent effects on apoptosis, varying with the death stimulus.
  • Cell cycle arrest induced by PSM-RB does not invariably confer resistance to apoptosis.
  • RB phosphorylation status significantly influences cellular responses to apoptotic signals.

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