Poster Presentation 35th Lorne Cancer Conference 2023

The long noncoding RNA glycoLINC assembles a lower glycolytic metabolon to reconcile the Warburg effect with the serine synthesis pathway (#368)

Yuan Yuan Zhang 1 , Rick Thorne 1 , Vinod Narayana 2 , David De Souza 2 , Xu Dong Zhang 1 , Lei Jin 1
  1. The University of Newcastle, Callaghan, NSW, Australia
  2. Metabolomics Australia, The University Melbourne, Parkville, VIC, Australia

Non-covalent complexes of glycolytic enzymes termed “metabolons” have been postulated for longer than 30 years, but experimental evidence in support of this concept is still lacking. Here show that a c-Myc-responsive long noncoding RNA (lncRNA) that we call glycoLINC (gLINC) acts as a backbone for metabolon formation between all four glycolytic payoff phase enzymes (PGK1, PGAM1, ENO1, and PKM2) along with lactate dehydrogenase A (LDHA). siRNA knockdown of gLINC upregulated the intracellular levels of serine and glycine, decreased the extracellular acidification rate (ECAR), and reduced the viability in cancer cells cultured in the medium deprived of serine/glycine, suggesting an increase in channelling the glycolytic intermediate 3-phosphoglyceric acid (3PG) toward synthesizing serine, attenuating the glycolytic payoff phase. Consolidating this notion, pulse labelling of cells with 13C-labeled glucose under serine/glycine starvation conditions demonstrated that gLINC knockdown retarded the glycolytic flux, as shown by 13C-incorporated 3PG, phosphoenolpyruvic acid (PEP), pyruvate, lactate, and alanine while enhancing the de novo biosynthesis of serine and glycine. Thus, gLINC functions to sustain glycolytic flux when 3PG availability is compromised by SSP activation. Interrogation of the protein interactome of gLINC revealed that gLINC bound to PGK1, ENO1, PKM2 and LDHA through discrete fragments, forming part of a multi-protein complex, whereas PGAM1 was present in the complex by virtue of its interaction with ENO1. The interactions between gLINC and these lower glycolytic enzymes and LDHA were substantiated in tumour xenografts harvested from mice fed with a serine/glycine-deprived diet. Moreover, gLINC depletion retards tumour xenograft growth in these mice. Collectively, our results provide the first example of a lncRNA-facilitated metabolon and suggest that gLINC makes a functional contribution to cancer cell adaptation to metabolic stress caused by serine starvation.