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JCI Insight. 2018 Jul 25;3(14). pii: 120422. doi: 10.1172/jci.insight.120422. [Epub ahead of print]

The RUNX1/IL-34/CSF-1R axis is an autocrinally regulated modulator of resistance to BRAF-V600E inhibition in melanoma.

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Department of Medicine, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York, USA.
Vanderbilt University, Nashville, Tennessee, USA.
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, USA.
Departments of Oncological Sciences & Dermatology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
Plexxikon, Berkeley, California, USA.
Department of Genetics and.
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York, USA.
Department of Chemistry and Biochemistry, Florida Atlantic University, Florida, USA.


Resistance to current therapies still impacts a significant number of melanoma patients and can be regulated by epigenetic alterations. Analysis of global cytosine methylation in a cohort of primary melanomas revealed a pattern of early demethylation associated with overexpression of oncogenic transcripts. Loss of methylation and associated overexpression of the CSF 1 receptor (CSF1R) was seen in a majority of tumors and was driven by an alternative, endogenous viral promoter in a subset of samples. CSF1R was particularly elevated in melanomas with BRAF and other MAPK activating mutations. Furthermore, rebound ERK activation after BRAF inhibition was associated with RUNX1-mediated further upregulation of CSF-1R and its ligand IL-34. Importantly, increased CSF-1R and IL-34 overexpression were detected in an independent cohort of resistant melanomas. Inhibition of CSF-1R kinase or decreased CSF-1R expression by RNAi reduced 3-D growth and invasiveness of melanoma cells. Coinhibition of CSF-1R and BRAF resulted in synergistic efficacy in vivo. To our knowledge, our data unveil a previously unknown role for the autocrine-regulated CSF-1R in BRAF V600E resistance and provide a preclinical rationale for targeting this pathway in melanoma.


Melanoma; Oncology

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