TY - JOUR
T1 - Pyruvate kinase expression (PKM1 and PKM2) in cancer associated fibroblasts drives stromal nutrient production and tumor growth
AU - Chiavarina, Barbara
AU - Whitaker-Menezes, Diana
AU - Martinez-Outschoorn, Ubaldo E.
AU - Witkiewicz, Agnieszka K.
AU - Birbe, Ruth C.
AU - Howell, Anthony
AU - Pestell, Richard G.
AU - Smith, Johanna
AU - Daniel, Rene
AU - Sotgia, Federica
AU - Lisanti, Michael P.
N1 - Funding Information:
then incubated with biotinylated rabbit anti-rat IgG (Vector Labs) F.S. and her laboratory were supported by grants from the and streptavidin-HRP (Dako). Immunoreactivity was revealed Breast Cancer Alliance (BCA) and the American Cancer Society with 3,3' diaminobenzidine. (ACS). U.E.M. was supported by a Young Investigator Award Determination of mitochondrial activity in situ. To assess the from the Margaret Q. Landenberger Research Foundation. mitochondrial oxidative phosphorylation of tumor samples, the M.P.L. was supported by grants from the NIH/NCI (R01-CA-activity of cytochrome C oxidase (COX, complex IV) was 080250, R01-CA-098779, R01-CA-120876 and R01-AR-determined in situ on frozen sections of tumor xenografts. 055660), and the Susan G. Komen Breast Cancer Foundation. Briefly, 7 mm thick cryostat sections from xenograft samples were A.K.W was supported by a Susan G. Komen Career Catalyst prepared from frozen tumor samples (n = 4 per group) and stored Grant. R.G.P. was supported by grants from the NIH/NCI (R01-at -80°C until use. To detect COX activity, frozen sections were CA-70896, R01-CA-75503, R01-CA-86072 and R01-CA-107382) equilibrated at room temperature, washed for 5 min with 25 mM and the Dr. Ralph and Marian C. Falk Medical Research Trust.
PY - 2011/12/15
Y1 - 2011/12/15
N2 - We have previously demonstrated that enhanced aerobic glycolysis and/or autophagy in the tumor stroma supports epithelial cancer cell growth and aggressive behavior, via the secretion of high-energy metabolites. These nutrients include lactate and ketones, as well as chemical building blocks, such as aminoacids (glutamine) and nucleotides. Lactate and ketones serve as fuel for cancer cell oxidative metabolism, and building blocks sustain the anabolic needs of rapidly proliferating cancer cells. We have termed these novel concepts the "Reverse Warburg Effect," and the "Autophagic Tumor Stroma Model of Cancer Metabolism." We have also identified a loss of stromal caveolin-1 (Cav-1) as a marker of stromal glycolysis and autophagy. The aim of the current study was to provide genetic evidence that enhanced glycolysis in stromal cells favors tumorigenesis. To this end, normal human fibroblasts were genetically-engineered to express the two isoforms of pyruvate kinase M (PKM1 and PKM2), a key enzyme in the glycolytic pathway. In a xenograft model, fibroblasts expressing PKM1 or PKM2 greatly promoted the growth of co-injected MDA-MB-231 breast cancer cells, without an increase in tumor angiogenesis. Interestingly, PKM1 and PKM2 promoted tumorigenesis by different mechanism(s). Expression of PKM1 enhanced the glycolytic power of stromal cells, with increased output of lactate. Analysis of tumor xenografts demonstrated that PKM1 fibroblasts greatly induced tumor inflammation, as judged by CD45 staining. In contrast, PKM2 did not lead to lactate accumulation, but triggered a "pseudo-starvation" response in stromal cells, with induction of an NFkB-dependent autophagic program, and increased output of the ketone body 3- hydroxy-buryrate. Strikingly, in situ evaluation of Complex IV activity in the tumor xenografts demonstrated that stromal PKM2 expression drives mitochondrial respiration specifically in tumor cells. Finally, immuno-histochemistry analysis of human breast cancer samples lacking stromal Cav-1 revealed PKM1 and PKM2 expression in the tumor stroma. Thus, our data indicate that a subset of human breast cancer patients with a loss of stromal Cav-1 show profound metabolic changes in the tumor microenvironment. As such, this subgroup of patients may benefit therapeutically from potent inhibitors targeting glycolysis, autophagy and/or mitochondrial activity (such as metformin).
AB - We have previously demonstrated that enhanced aerobic glycolysis and/or autophagy in the tumor stroma supports epithelial cancer cell growth and aggressive behavior, via the secretion of high-energy metabolites. These nutrients include lactate and ketones, as well as chemical building blocks, such as aminoacids (glutamine) and nucleotides. Lactate and ketones serve as fuel for cancer cell oxidative metabolism, and building blocks sustain the anabolic needs of rapidly proliferating cancer cells. We have termed these novel concepts the "Reverse Warburg Effect," and the "Autophagic Tumor Stroma Model of Cancer Metabolism." We have also identified a loss of stromal caveolin-1 (Cav-1) as a marker of stromal glycolysis and autophagy. The aim of the current study was to provide genetic evidence that enhanced glycolysis in stromal cells favors tumorigenesis. To this end, normal human fibroblasts were genetically-engineered to express the two isoforms of pyruvate kinase M (PKM1 and PKM2), a key enzyme in the glycolytic pathway. In a xenograft model, fibroblasts expressing PKM1 or PKM2 greatly promoted the growth of co-injected MDA-MB-231 breast cancer cells, without an increase in tumor angiogenesis. Interestingly, PKM1 and PKM2 promoted tumorigenesis by different mechanism(s). Expression of PKM1 enhanced the glycolytic power of stromal cells, with increased output of lactate. Analysis of tumor xenografts demonstrated that PKM1 fibroblasts greatly induced tumor inflammation, as judged by CD45 staining. In contrast, PKM2 did not lead to lactate accumulation, but triggered a "pseudo-starvation" response in stromal cells, with induction of an NFkB-dependent autophagic program, and increased output of the ketone body 3- hydroxy-buryrate. Strikingly, in situ evaluation of Complex IV activity in the tumor xenografts demonstrated that stromal PKM2 expression drives mitochondrial respiration specifically in tumor cells. Finally, immuno-histochemistry analysis of human breast cancer samples lacking stromal Cav-1 revealed PKM1 and PKM2 expression in the tumor stroma. Thus, our data indicate that a subset of human breast cancer patients with a loss of stromal Cav-1 show profound metabolic changes in the tumor microenvironment. As such, this subgroup of patients may benefit therapeutically from potent inhibitors targeting glycolysis, autophagy and/or mitochondrial activity (such as metformin).
KW - Aerobic glycolysis
KW - Autophagy
KW - Cancer associated fibroblasts
KW - Caveolin-1
KW - Ketone body
KW - Lactate
KW - Metabolic coupling
KW - PKM1
KW - PKM2
KW - Pyruvate kinase M
KW - Tumor stroma
KW - Warburg effect
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UR - http://www.scopus.com/inward/citedby.url?scp=84055199818&partnerID=8YFLogxK
U2 - 10.4161/cbt.12.12.18703
DO - 10.4161/cbt.12.12.18703
M3 - Article
C2 - 22236875
AN - SCOPUS:84055199818
SN - 1538-4047
VL - 12
SP - 1101
EP - 1113
JO - Cancer Biology and Therapy
JF - Cancer Biology and Therapy
IS - 12
ER -