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The molecular scaffold KSR1 regulates the proliferative and oncogenic potential of cells

Robert L Kortum1, Robert E Lewis

  • 1Eppley Institute for Cancer Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA.

Molecular and Cellular Biology
|May 4, 2004
PubMed

Insights

The molecular scaffold KSR1 controls ERK pathway signaling duration, impacting cell proliferation and cancer development. Optimal KSR1 levels enhance cellular growth and oncogenic potential by fine-tuning growth factor and oncogene actions.

Area of Science:

  • Molecular biology
  • Cell signaling
  • Oncogenesis

Background:

  • Mitogen-activated protein kinase (MAPK) pathway specificity relies on signaling intensity, duration, and protein scaffolds.
  • KSR1 (Kinase Suppressor of Ras 1) is a key scaffold protein in MAPK signaling.

Purpose of the Study:

  • To investigate the role of KSR1 in regulating ERK (Extracellular signal-regulated kinase) activation intensity and duration.
  • To determine how KSR1 modulates cellular proliferative and oncogenic potential.

Main Methods:

  • Utilized KSR1 knockout (KSR1(-/-)) mouse embryo fibroblasts.
  • Assessed ERK activation in response to platelet-derived growth factor (PDGF).
  • Investigated the effect of Ras(V12) oncogene-induced transformation and KSR1 reintroduction at varying concentrations.

Main Results:

  • KSR1 deletion abolished prolonged ERK activation by PDGF and blocked Ras(V12)-induced transformation.
  • KSR1 reintroduction showed a dose-dependent increase in signaling and transformation, with inhibition at supra-optimal levels.
  • Optimal KSR1 expression maximized ERK cascade association, leading to a threefold increase in proliferative capacity.

Conclusions:

  • KSR1 is crucial for regulating ERK signaling intensity and duration, thereby controlling cell proliferation and oncogenesis.
  • Cells possess latent proliferative capacity that can be unlocked by optimal expression of scaffolds like KSR1.
  • Modulating scaffold protein expression levels offers a mechanism to control growth factor and oncogene activity.

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