Succinate-to-Fumarate Ratio as a New Metabolic Marker to Detect the Presence of SDHB/D-related Paraganglioma: Initial Experimental and Ex Vivo Findings

Pheochromocytomas (PHEOs) and paragangliomas (PGLs; extra-adrenal tumors) are rare neuroendocrine chromaffin cell tumors with a hereditary background in about 30%–35%. Those caused by succinate dehydrogenase subunit B (SDHB) germline mutations are associated with a high metastatic potential and ultimately higher patient mortality. Succinate dehydrogenase converts succinate to fumarate, uniquely linking the Krebs cycle and oxidative phosphorylation. SDH mutations result in the accumulation of succinate associated with various metabolic disturbances and the shift to aerobic glycolysis in tumor tissue. In the present study, we measured succinate and fumarate levels in mouse pheochromocytoma (MPC) and mouse tumor tissue (MTT) cells and in 10 apparently sporadic, 10 SDHB-, 5 SDHD-, and 2 neurofibromatosis 1–related PHEOs/PGLs and plasma samples using mass spectrometry. We found that the succinate-to-fumarate ratio was significantly higher in the SDHB- and SDHD-related PGLs than in apparently sporadic and neuro...