Related Experiment Video

Updated: Jun 16, 2026

Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells
06:09

Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells

Published on: June 7, 2019

Dissection of RAS downstream pathways in melanomagenesis: a role for Ral in transformation

P J Mishra1, L Ha, J Rieker

  • 1Laboratory of Cancer Biology and Genetics, National Cancer Institute, NIH, Bethesda, MD 20892-4264, USA.

Oncogene
|February 2, 2010
PubMed

Insights

Investigating NRas downstream effectors in melanoma, this study found that while BRAF and PI3K influence senescence and invasiveness, Ral guanine exchange factor (RalGEF) activation significantly impacts malignant growth, suggesting it as a potential therapeutic target.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cancer Research

Background:

  • Cutaneous malignant melanoma is a deadly cancer known for metastasis and therapy resistance.
  • Melanomas frequently harbor oncogenic NRAS or BRAF mutations, which rarely coexist, suggesting overlapping functions.
  • NRAS downstream effectors, including Raf, PI3K, and RalGEF, are critical in melanoma pathogenesis.

Purpose of the Study:

  • To compare the oncogenic roles of three major NRas downstream effectors: Raf, PI3K, and RalGEF.
  • To elucidate the specific contributions of these pathways to melanoma development and progression.
  • To identify potential novel therapeutic targets within the NRas signaling network.

Main Methods:

  • Utilized genetically engineered Arf-deficient immortalized mouse melanocytes as a model system.
  • Compared and contrasted the functional consequences of activating Raf, PI3K, and RalGEF pathways.
  • Assessed key malignant phenotypes including senescence, invasiveness, and anchorage-independent growth.

Main Results:

  • No single NRas effector pathway fully replicated all oncogenic NRas consequences.
  • BRAF activation was linked to melanocyte senescence.
  • PI3K activation was associated with increased melanocyte invasiveness.
  • Constitutive RalGEF activation significantly impacted multiple malignant phenotypes, notably anchorage-independent growth.

Conclusions:

  • While BRAF and PI3K play roles in specific melanoma phenotypes, RalGEF activation demonstrates a broader impact on malignant transformation.
  • The RalGEF pathway, often overlooked, warrants further investigation as a potential therapeutic target in melanoma.
  • Understanding the distinct and overlapping roles of NRas downstream effectors is crucial for developing effective melanoma therapies.

More Related Videos

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods07:49

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods

Published on: July 17, 2019

Identification of EGFR and RAS Inhibitors using Caenorhabditis elegans08:12

Identification of EGFR and RAS Inhibitors using Caenorhabditis elegans

Published on: October 5, 2020

Related Concept Videos

The Ras Gene02:38

The Ras Gene

The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
MAPK Signaling Cascades01:07

MAPK Signaling Cascades

Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
Small GTPases - Ras and Rho01:24

Small GTPases - Ras and Rho

Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
The Ras Gene02:38

The Ras Gene

The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
Interactions Between Signaling Pathways01:19

Interactions Between Signaling Pathways

Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...