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Updated: May 1, 2026
Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells
Published on: June 7, 2019
Near-genomewide RNAi screening for regulators of BRAF(V600E) -induced senescence identifies RASEF, a gene
Joanna Kaplon1, Cornelia Hömig-Hölzel, Linda Gao
1Division of Molecular Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Abstract:
The activation of oncogenes in primary cells blocks proliferation by inducing oncogene-induced senescence (OIS), a highly potent in vivo tumor-suppressing program. A prime example is mutant BRAF, which drives OIS in melanocytic nevi. Progression to melanoma occurs only in the context of additional alteration(s) like the suppression of PTEN, which abrogates OIS. Here, we performed a near-genomewide short hairpin (sh)RNA screen for novel OIS regulators and identified by next generation sequencing and functional validation seven genes. While all but one were upregulated in OIS, depletion of each of them abrogated BRAF(V) (600E) -induced arrest. With genome-wide DNA methylation analysis, we found one of these genes, RASEF, to be hypermethylated in primary cutaneous melanomas but not nevi. Bypass of OIS by depletion of RASEF was associated with suppression of several senescence biomarkers including senescence-associated (SA)-β-galactosidase activity, interleukins, and tumor suppressor p15(INK) (4B) . Restoration of RASEF expression inhibited proliferation. These results illustrate the power of shRNA OIS bypass screens and identify a potential novel melanoma suppressor gene.
Insights
Oncogene-induced senescence (OIS) suppresses tumors. Researchers identified seven new OIS regulators using a short hairpin RNA screen, finding RASEF may be a novel melanoma suppressor gene.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- Oncogene activation triggers oncogene-induced senescence (OIS), a tumor-suppressing mechanism.
- Mutant BRAF induces OIS in melanocytic nevi, but melanoma progression involves OIS evasion.
- PTEN loss is one mechanism that abrogates OIS, allowing melanoma development.
Purpose of the Study:
- To identify novel regulators of oncogene-induced senescence (OIS).
- To investigate the role of identified regulators in melanoma progression.
- To explore RASEF as a potential melanoma suppressor gene.
Main Methods:
- Conducted a near-genome-wide short hairpin (sh)RNA screen to identify OIS regulators.
- Utilized next-generation sequencing and functional validation for gene identification.
- Performed genome-wide DNA methylation analysis and assessed senescence biomarkers.
Main Results:
- Identified seven novel genes that regulate OIS; depletion abrogated BRAF(V600E)-induced cell cycle arrest.
- RASEF was found to be hypermethylated in primary cutaneous melanomas but not nevi.
- Depletion of RASEF suppressed senescence biomarkers, and its restoration inhibited proliferation.
Conclusions:
- shRNA OIS bypass screens are powerful tools for discovering senescence regulators.
- RASEF functions as a regulator of OIS and exhibits characteristics of a melanoma suppressor gene.
- RASEF's epigenetic silencing in melanoma suggests its potential as a therapeutic target.
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