Somatic Mutation of GRIN2A in Malignant Melanoma Results in Loss of Tumor Suppressor Activity via Aberrant NMDAR Complex Formation

Abstract

The ionotropic glutamate receptors (NMDAR) are composed of large complexes of multi-protein subunits creating ion channels in the cell plasma membranes that allow for influx or efflux of mono- or divalent cations (e.g., Ca2+) important for synaptic transmissions, cellular migration and survival. Recently, we discovered the high prevalence of somatic mutations within one of the ionotropic glutamate receptors, GRIN2A, in malignant melanoma. Functional characterization of a subset of GRIN2A mutants demonstrated a loss of NMDAR complex formation between GRIN1 and GRIN2A, increased anchorage-independent growth in soft agar, and increased migration. Somatic mutation of GRIN2A results in a dominant negative effect inhibiting the tumor suppressive phenotype of wild type GRIN2A in melanoma. Depletion of endogenous GRIN2A in melanoma cells expressing wild-type GRIN2A resulted in increased proliferation compared to control. In contrast, shRNA depletion of GRIN2A in mutant cell lines slightly reduced proliferation. Our data shows that somatic mutation of GRIN2A results in increased survival and is the first such report to demonstrate the functional importance of GRIN2A mutations in melanoma and the significance ionotropic glutamate receptor signaling plays in malignant melanoma.

The Distinctive Mutational Spectra of Polyomavirus-Negative Merkel Cell Carcinoma

“…PRUNE2 , a proapoptotic factor (24), is mutated in 20% of melanomas (The Cancer Genome Atlas). We identified two inactivating mutations in the glutamate receptor subunit GRIN2A (2/8, 25%): a splice site mutation and the (R902K) loss-of-function mutation described in melanoma (25)(Supplemental Tables S6-S7). Further, we discovered a novel missense mutation in the DNA damage response gene BRCA2 (D2819V) affecting the DNA binding domain (Supplemental Table S6).…”

Physiological Roles of Non-Neuronal NMDA Receptors

“…In [129,198] Small-cell GluN1; GluN2A-C [134] Connective tissue (muscle, bone) Sarcoma GluN1; GluN2A-D; GluN3A,B [198] Thyroid Carcinoma GluN1; GluN2B-D; GluN3A,B [198] Plasma cell Multiple myeloma GluN1; GluN2A-D [198] Colon/rectum Adenocarcinoma GluN1; GluN2A-D; GluN3A [129,138,198,199] T cell Leukemia GluN2A-D; GluN3A [198] Breast Adenocarcinoma GluN1; GluN2A-D; GluN3A [126,129,198] Ovaries Cystadenocarcinoma GluN1; GluN2B [202] Endometrioid adenocarcinoma GluN1; GluN2B [202] Clear-cell carcinoma GluN1; GluN2B [202] Megakaryoblasts Leukemic megarkaryoblasts GluN1; GluN2A-D; GluN3A,B [132] Oral cavity Squamous cell carcinoma GluN1 [140,141] Larynx Squamous cell carcinoma GluN1; GluN2A-D; GluN3A [136] Bone Osteosarcoma GluN1; GluN2A,B,D; GluN3A [203] accordance, ectopic GluN2B overexpression induced NMDAR-mediated apoptosis in gastric [144] and esophageal squamous cell carcinoma cells [143], and GluN2A overexpression stimulated colorectal cancer cell death [146]. In addition, whole-exome sequencing in malignant melanoma tumor samples revealed a significant prevalence of clustered mutations within GRIN2A functional domains, leading to truncated GluN2A [147], reduced NMDAR complex formation, and increased cancer cell growth, migration [148], and disease progression [149].…”

Cutaneous malignant melanoma and Parkinson disease: Common pathways?

“…112 GRIN2A in CMM Tissue and PD The gene encoding for the ionotropic glutamate receptor subunit, GRIN2A, is somatically mutated in about onethird of CMM samples. 115 CMM patients with nonsynonymous GRIN2A mutations have a more aggressive course with fast progression and shorter survival compared with noncarriers. Functional characterization of a subset of GRIN2A somatic truncating mutants demonstrated reduced NMDA receptor complex formation between GRIN1 and GRIN2A.…”

“…110 Inhibiting PTEN expression alters the response of striatal neurons to dopamine, and normal responses of these neurons to D2 agonists appear to require the presence of PTEN and/or reduction in AKT activity. 115 In this still hypothetical model, GRIN2A may function as a tumor suppressor in melanoma cells. 61,113,114 GRIN2A encodes an ionic glutamate N-methyl-D-aspartate (NMDA) receptor subunit.…”

“…This could induce decreased Ca2 1 influx through the cation channel, potentially leading to increased survival through suppression of cell death via apoptosis (excitotoxicity). 115 In this still hypothetical model, GRIN2A may function as a tumor suppressor in melanoma cells. 115 CMM patients with nonsynonymous GRIN2A mutations have a more aggressive course with fast progression and shorter survival compared with noncarriers.…”