Abstract
BackgroundLysine succinylation is an emerging posttranslational modification that has garnered increased attention recently, but its role in gastric cancer (GC) remains underexplored.MethodsProteomic quantification of lysine succinylation was performed in human GC tissues and adjacent normal tissues by mass spectrometry. The mRNA and protein levels of lactate dehydrogenase A (LDHA) in GC and adjacent normal tissues were analyzed by qRT-PCR and western blot, respectively. The expression of K222-succinylated LDHA was measured in GC tissue microarray by the K222 succinylation-specific antibody. The interaction between LDHA and sequestosome 1 (SQSTM1) was measured by co-immunoprecipitation (co-IP) and proximity ligation assay (PLA). The binding of carnitine palmitoyltransferase 1A (CPT1A) to LDHA was determined by co-IP. The effect of K222-succinylated LDHA on tumor growth and metastasis was evaluated by in vitro and in vivo experiments.ResultsAltogether, 503 lysine succinylation sites in 303 proteins were identified. Lactate dehydrogenase A (LDHA), the key enzyme in Warburg effect, was found highly succinylated at K222 in GC. Intriguingly, this modification did not affect LDHA ubiquitination, but reduced the binding of ubiquitinated LDHA to SQSTM1, thereby decreasing its lysosomal degradation. We demonstrated that CPT1A functions as a lysine succinyltransferase that interacts with and succinylates LDHA. Moreover, high K222-succinylation of LDHA was associated with poor prognosis in patients with GC. Finally, overexpression of a succinylation-mimic mutant of LDHA promoted cell proliferation, invasion, and migration.ConclusionsOur data revealed a novel lysosomal pathway of LDHA degradation, which is mediated by the binding of K63-ubiquitinated LDHA to SQSTM1. Strikingly, CPT1A succinylates LDHA on K222, which thereby reduces the binding and inhibits the degradation of LDHA, as well as promotes GC invasion and proliferation. This study thus uncovers a new role of lysine succinylation and the mechanism underlying LDHA upregulation in GC.
Highlights
Lysine succinylation is an emerging posttranslational modification that has garnered increased attention recently, but its role in gastric cancer (GC) remains underexplored
The protein succinylation landscape significantly differs between gastric cancer tissues and adjacent normal tissues In order to study the effect of protein posttranslational modification (PTM) in GC, we selected seven patients with primary GC who had not received any treatment before surgery, and surgically extracted their tumor tissues and adjacent normal tissues for the study
K222-succinylated Lactate dehydrogenase A (LDHA) is associated with poor prognosis in patients with GC To analyze the association of LDHA The succinylation of LDHA at lysine 222 (K222suc) and prognosis of patients with GC, the specific K222suc antibody was employed to conduct tissue microarray-based IHC
Summary
Lysine succinylation is an emerging posttranslational modification that has garnered increased attention recently, but its role in gastric cancer (GC) remains underexplored. Hundreds of PTMs have been discovered, including phosphorylation, methylation, acetylation, glycosylation, succinylation, biotinylation, ubiquitination, SUMOylation, propionylation, butyrylation, lactylation, etc. In 2011, succinylation was first shown as a naturally occurring PTM on lysine residues in bacteria [6]. Lysine acetyltransferase 2A (KAT2A) and carnitine palmitoyltransferase 1A (CPT1A) were recently uncovered as succinylating enzymes [10,11,12]. The role of lysine succinylation in GC remains poorly understood. Our previous results showed that succinylation was more a consistent protein modification than crotonylation and acetylation in GC and adjacent tissues, and succinylation of S100A10 by CPT1A promoted human gastric cancer (GC) invasion [13]
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