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OBJECTIVES

Determine whether EGFR and ERBB2 are sufficient and necessary to drive increased proliferation of the four ERBB4-dependent BRAF WT melanoma cell lines (MEL-JUSO, IPC-298, SK-MEL-2 and MeWo).

Determine whether EGFR or ERBB2 enable ERBB4 melanoma mutants to cause increased ligand-dependent or ligand-independent proliferation of the 32D mouse lymphoid cells.

Determine whether the sensitivity of BRAF WT melanoma cell lines to inhibitors of EGFR and ERBB2 respond to changes in ERBB4 signaling.

RESULTS

The different effects of EGFR and ERBB2 on the clonogenic proliferation of BRAF WT melanoma cell lines may reflect a gender disparity.

2. The ERBB4 ligand NRG1beta stimulates IL3-independent proliferation of 32D/ERBB2+ERBB4 cells but does not stimulate IL3-independent proliferation of 32D cells that express only ERBB2 or ERBB4.

RECENT UNPUBLISHED WORK

ERBB4 is both sufficient and necessary for the clonogenic proliferation of the MEL-JUSO BRAF WT melanoma cell line

ERBB4 is both sufficient and necessary for the clonogenic proliferation of four BRAF WT melanoma cell lines

The G85S and G741E ERBB4 mutant alleles found in BRAF WT melanomas stimulate clonogenic proliferation of MEL-JUSO cells, but the synthetic constitutively dimerized Q646C mutant inhibits clonogenic proliferation

Among deceased BRAF WT melanoma patients, an ERBB4 mutation is associated with male patients to a greater degree than female patients.

ERBB4 Heterodimers Appear to Drive BRAF WT Melanoma Cell Lines

Vipasha Dwivedi¹, Lauren Lucas¹, Rees Cooke¹,Jen Davis¹, Ella Wilson¹, Markelle Scott¹, Kaitlyn O’Daniel¹,

Chloe Dion¹, Jaxon Kerley¹, Madison Zelan¹, Nick DeFeo¹, Tori Huffman¹, Maddy Ingrao¹, and David J. Riese II^1,2

¹Department of Drug Discovery and Development, Harrison College of Pharmacy, Auburn University, Auburn, AL 36849 USA

²Cancer Biology and Immunology Program, O’Neal Comprehensive Cancer Center, The University of Alabama at Birmingham, AL 35294 USA

FUTURE HYPOTHESES

ERBB4-EGFR heterodimers account for the gender disparity in BRAF WT melanomas.

EGFR or ERBB2 differentially enable ERBB4 melanoma mutants to cause increased ligand-dependent or ligand-independent proliferation

The sensitivity of BRAF WT melanoma cell lines to inhibitors of EGFR and ERBB2 responds to changes in ERBB4 signaling.

ERBB2 and/or EGFR dimerization domain mutants rescue ERBB4 dimerization domain mutants.

PRELIMINARY CONCLUSIONS

ERBB2 is necessary for the clonogenic proliferation of the MEL-JUSO and IPC-298 female BRAF WT melanoma cell lines.

ERBB2 and EGFR are necessary for the clonogenic proliferation of the male MeWo BRAF WT melanoma cell line.

The 32D/ERBB2+ERBB4 cell line is a good model for studying ligand-dependent and –independent coupling of ERBB2+ERBB4 heterodimers to cell proliferation.

ACKNOWLEDGEMENTS & DISCLOSURES

This research has been funded by NIH grants R01CA114209 and R15CA280767 and the US Department of Education GAANN Graduate Fellowship Program Award P200A120244.

This research has also been supported by an Auburn University Presidential Graduate Research Fellowship to LML, the Auburn University Research Initiative in Cancer, the Department of Drug Discovery and Development, the Harrison College of Pharmacy and the Auburn University Office of the Vice President for Research.

DJR has been a consultant to Eli Lilly, Imclone, and Bristol-Myers Squibb.

Contact Information:

Dr. Vipasha Dwivedi – vzd0020@auburn.edu

Dr. David Riese – driese@auburn.edu

PREMISE & HYPOTHESIS

Approximately half of the metastatic melanomas harbor a BRAF V600E mutation and respond to inhibitors of BRAF pathway signaling. However, the metastatic melanomas which possess wild-type (WT) BRAF alleles are just as aggressive as BRAF V600E tumors and no therapeutic targets have been identified for these tumors. Thus, our goal is to identify candidate targets for therapeutic intervention in BRAF-WT melanomas
ERBB4 (HER4) is a receptor tyrosine kinase that is closely related to the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3)
Upon ligand binding, ERBB receptors homo- or heterodimerize, resulting in dimer-specific downstream signaling events. ERBB4-EGFR and ERBB4-ERBB2 heterodimers are known to stimulate the PI3K/Akt signaling pathway.
Several groups have demonstrated that ERBB4-EGFR and ERBB4-ERBB2 heterodimers function as oncoproteins, whereas ERBB4 homodimers function as tumor suppressors.
Our unpublished in silico analyses of BRAF-WT melanoma genomes and transcriptomes suggest that elevated ERBB4 expression or gain-of-function ERBB4 mutations drive melanoma tumor progression by cooperating with elevated RAS signaling and by stimulating the canonical PI3K/Akt pathway.
Our preliminary data indicate that ERBB4 is both sufficient and necessary for proliferation of BRAF-WT melanoma cell lines.
Therefore, we hypothesize that ERBB4-EGFR or ERBB4-ERBB2 heterodimers drive proliferation of BRAF-WT melanoma cell lines.
ERBB4 homodimers and heterodimers are functionally distinct
ERBB4 homodimers function as tumor suppressor whereas ERBB4 heterodimers are oncogenic.