Monoclonal antibody-induced ErbB3 receptor internalization and degradation inhibits growth and migration of human melanoma cells

Abstract

Members of the ErbB receptor family are targets of a growing numbers of small molecules and monoclonal antibodies inhibitors currently under development for the treatment of cancer. Although historical efforts have been directed against ErbB1 (EGFR) and ErbB2 (HER2/neu), emerging evidences have pointed to ErbB3 as a key node in the activation of proliferation/survival pathways from the ErbB receptor family and have fueled enthusiasm toward the clinical development of anti-ErbB3 agents. In this study, we have evaluated the potential therapeutic efficacy of a set of three recently generated anti-human ErbB3 monoclonals, A2, A3 and A4, in human primary melanoma cells. We show that in melanoma cells expressing ErbB1, ErbB3 and ErbB4 but not ErbB2 receptor ligands activate the PI3K/AKT pathway, and this leads to increased cell proliferation and migration. While antibodies A3 and A4 are able to potently inhibit ligand-induced signaling, proliferation and migration, antibody A2 is unable to exert this effect. In attempt to understand the mechanism of action and the basis of this different behavior, we demonstrate, through a series of combined approaches, that antibody efficacy strongly correlates with antibody-induced receptor internalization, degradation and inhibition of receptor recycling to the cell surface. Finally, fine epitope mapping studies through a peptide array show that inhibiting vs. non-inhibiting antibodies have a dramatically different mode of binding to the to the receptor extracellular domain. Our study confirms the key role of ErbB3 and points to exploitation of novel combination therapies for treatment of malignant melanoma.

The anti-HER3 (ErbB3) therapeutic antibody 9F7-F11 induces HER3 ubiquitination and degradation in tumors through JNK1/2- dependent ITCH/AIP4 activation

“…Targeting EGFR or HER2 by antibody-mediated ubiquitination and degradation [24, 25, 27–29, 51] is one attractive way to improve therapeutic benefit in patients. Such mechanism has been also proposed for antibodies against HER3 [15, 50, 52, 53] or IGFR1 [54]. Pre-clinical studies using anti-HER3 antibodies clearly identified receptor degradation as a marker of drug efficacy [55].…”

ERBB3 is required for metastasis formation of melanoma cells

“…23, 40 Consequently, both ERBB3-specific and pan-ERBB inhibitors were shown to effectively curb the progression of melanoma. 25, 37, 38 Most of these studies investigate the effects of ERBB3 on primary tumor growth but not metastasis. Our results suggest that ERBB3 inhibition may block the metastatic growth of melanoma cells, and this suppressive role appears to be effective regardless of their sensitivity to BIs.…”

“…20 Its downregulation by short hairpin RNA (shRNA) or inhibition by small inhibitors led to a reduction in melanoma cell proliferation or subcutaneous melanoma growth. 22, 23, 24, 25, 26 Nevertheless, how ERBB3 regulates melanoma metastasis and whether its inhibition could serve as a therapeutic approach for treating metastatic melanoma are not clear.…”

Dysregulation of ErbB Receptor Trafficking and Signaling in Demyelinating Charcot-Marie-Tooth Disease

“…Mek inhibitor, such as CI-1040 and U0126, has been shown to reduce the augmented Erk signaling and demyelination phenotype in rodent models of CMT1A [27, 107] and CMT1X [112]. In addition, agents such as geldanamycin [121] and ErbB receptor-specific monoclonal antibodies [122–124] that facilitate ErbB receptor endocytosis and degradation could be explored in preclinical studies for treating certain forms of CMT with elevated ErbB levels and augmented Erk signaling (Table 2). Furthermore, given the critical role of phosphoinositides in modulation of ErbB receptor trafficking and signaling and their involvement in CMT pathogenesis, phosphoinositide kinase and/or phosphatase inhibitors [125–127] could be tested for potential therapeutic effects to reduce ErbB receptor trafficking and signaling defects and ameliorate demyelinating CMT neuropathy.…”