Journal Article

Cysteine catabolism and the serine biosynthesis pathway support pyruvate production during pyruvate kinase knockdown in pancreatic cancer cells

Teoh, Shao Thing, Yang, Che, Lunt, Sophia Y., Ogrodzinski, Martin P., Vazquez, Ana I., Ensink, Elliot, Yu, Lei

2019

Overview

Background Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with limited treatment options. Pyruvate kinase, especially the M2 isoform (PKM2), is highly expressed in PDAC cells, but its role in pancreatic cancer remains controversial. To investigate the role of pyruvate kinase in pancreatic cancer, we knocked down PKM2 individually as well as both PKM1 and PKM2 concurrently (PKM1/2) in cell lines derived from a Kras G12D/- ; p53 -/- pancreatic mouse model. Methods We used liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine metabolic profiles of wildtype and PKM1/2 knockdown PDAC cells. We further used stable isotope-labeled metabolic precursors and LC-MS/MS to determine metabolic pathways upregulated in PKM1/2 knockdown cells. We then targeted metabolic pathways upregulated in PKM1/2 knockdown cells using CRISPR/Cas9 gene editing technology. Results PDAC cells are able to proliferate and continue to produce pyruvate despite PKM1/2 knockdown. The serine biosynthesis pathway partially contributed to pyruvate production during PKM1/2 knockdown: knockout of phosphoglycerate dehydrogenase in this pathway decreased pyruvate production from glucose. In addition, cysteine catabolism generated ~ 20% of intracellular pyruvate in PDAC cells. Other potential sources of pyruvate include the sialic acid pathway and catabolism of glutamine, serine, tryptophan, and threonine. However, these sources did not provide significant levels of pyruvate in PKM1/2 knockdown cells. Conclusion PKM1/2 knockdown does not impact the proliferation of pancreatic cancer cells. The serine biosynthesis pathway supports conversion of glucose to pyruvate during pyruvate kinase knockdown. However, direct conversion of serine to pyruvate was not observed during PKM1/2 knockdown. Investigating several alternative sources of pyruvate identified cysteine catabolism for pyruvate production during PKM1/2 knockdown. Surprisingly, we find that a large percentage of intracellular pyruvate comes from cysteine. Our results highlight the ability of PDAC cells to adaptively rewire their metabolic pathways during knockdown of a key metabolic enzyme.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Adenocarcinoma / Amino acids / Aqueous solutions / Biomedical and Life Sciences / Biomedicine / Biosynthesis / Cancer cells / Cancer Research / Cancer therapies / Cancer treatment / Cell Biology / Cell growth / Chromatography / CRISPR / Cysteine / Cystine / Deoxyribonucleic acid / Design / DNA / Enzymes / Gene expression / Genes / Genome editing / Glucose / Glutamine / Imaging / Immunoglobulins / Isotopes / Kinases / Liquid chromatography / Liquid chromatography mass spectrometry / Lung cancer / Mass spectrometry / Metabolic Diseases / Metabolism / Metabolites / Metabolomics / Oncology / Organic acids / Pancreatic cancer / PKM / Plasmids / Proteins / Pyruvate kinase / Radiology / Serine / Spectroscopy / Technology / Thiols / Tryptophan / Tumor proteins / Vectors (Biology)