Mass Spectrometry-Based Metabolic Fingerprinting Contributes to Unveil the Role of RSUME in Renal Cell Carcinoma Cell Metabolism

Clear cell renal cell carcinoma (ccRCC)
is a heterogeneous disease with 50–80% patients exhibiting
mutations in the von Hippel–Lindau (VHL) gene. RSUME (RWD domain
(termed after three major RWD-containing proteins: RING finger-containing
proteins, WD-repeat-containing proteins, and yeast DEAD (DEXD)-like
helicases)-containing protein small ubiquitin-related modifier (SUMO)
enhancer) acts as a negative regulator of VHL function in normoxia.
A discovery-based metabolomics approach was developed by means of
ultraperformance liquid chromatography coupled to quadrupole time-of-flight
mass spectrometry (MS) for fingerprinting the endometabolome of a
human ccRCC cell line 786-O and three other transformed cell systems
(n = 102) with different expressions of RSUME and
VHL. Cross-validated orthogonal projection to latent structures discriminant
analysis models were built on positive, negative, and a combination
of positive- and negative-ion mode MS data sets. Discriminant feature
panels selected by an iterative multivariate classification allowed
differentiating cells with different expressions of RSUME and VHL.
Fifteen identified discriminant metabolites with level 1, including
glutathione, butyrylcarnitine, and acetylcarnitine, contributed to
understand the role of RSUME in ccRCC. Altered pathways associated
with the RSUME expression were validated by biological and bioinformatics
analyses. Combined results showed that in the absence of VHL, RSUME
is involved in the downregulation of the antioxidant defense system, whereas in the
presence of VHL, it acts in rerouting energy-related pathways, negatively
modulating the lipid utilization, and positively modulating the fatty
acid synthesis, which may promote deposition in droplets.