Deep Membrane Proteome Profiling Reveals Overexpression of Prostate-Specific Membrane Antigen (PSMA) in High-Risk Human Paraganglioma and Pheochromocytoma, Suggesting New Theranostic Opportunity

Abstract

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors arising from chromaffin cells of adrenal medulla or sympathetic or parasympathetic paraganglia, respectively. To identify new therapeutic targets, we performed a detailed membrane-focused proteomic analysis of five human paraganglioma (PGL) samples. Using the Pitchfork strategy, which combines specific enrichments of glycopeptides, hydrophobic transmembrane segments, and non-glycosylated extra-membrane peptides, we identified over 1800 integral membrane proteins (IMPs). We found 45 “tumor enriched” proteins, i.e., proteins identified in all five PGLs but not found in control chromaffin tissue. Among them, 18 IMPs were predicted to be localized on the cell surface, a preferred drug targeting site, including prostate-specific membrane antigen (PSMA), a well-established target for nuclear imaging and therapy of advanced prostate cancer. Using specific antibodies, we verified PSMA expression in 22 well-characterized human PPGL samples. Compared to control chromaffin tissue, PSMA was markedly overexpressed in high-risk PPGLs belonging to the established Cluster 1, which is characterized by worse clinical outcomes, pseudohypoxia, multiplicity, recurrence, and metastasis, specifically including SDHB, VHL, and EPAS1 mutations. Using immunohistochemistry, we localized PSMA expression to tumor vasculature. Our study provides the first direct evidence of PSMA overexpression in PPGLs which could translate to therapeutic and diagnostic applications of anti-PSMA radio-conjugates in high-risk PPGLs.

Identification of potential molecular targets for the imaging and treatment of cluster 1 human pheochromocytoma and paraganglioma via comprehensive proteomic characterization

“…Quadruple analysis of each sample ensured a high membrane proteome coverage. This strategy has already been shown to be effective in a small pilot experiment preceding the current project, where we identi ed the upregulated cell-surface protein PSMA as a potential theranostic target in PSMA in cluster 1 PPGLs [17].…”

Proteomics analysis of carotid body tumor revealed potential mechanisms and molecular differences among Shamblin classifications

“…As they are a minority among head and neck PGLs, CBTs have rarely been studied. Although differences between CBT exomes and differences in the mass spectra of head and neck PGLs have been reported, 22,23 the related differences and possible molecular mechanisms of proteins in the growth of CBT tumor tissues have not been studied. With the advent of mass spectrometers that can analyze complex protein mixtures rapidly and affordably, it is feasible to systematically analyze all proteins in tumors.…”

Identification of potential molecular targets for the treatment of cluster 1 human pheochromocytoma and paraganglioma via comprehensive proteomic characterization

“…Quadruple analysis of each sample ensured a high membrane proteome coverage. This strategy has already been shown to be effective in a small pilot experiment preceding the current project, where we identified the upregulated cell-surface protein PSMA as a potential theranostic target in PSMA in cluster 1 PPGLs [ 17 ].…”