Oncotarget

Research Papers: Pathology:

Unique metabolic features of pancreatic cancer stroma: relevance to the tumor compartment, prognosis, and invasive potential

Erik S. Knudsen, Uthra Balaji, Elizaveta Freinkman, Peter McCue and Agnieszka K. Witkiewicz _

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Oncotarget. 2016; 7:78396-78411. https://doi.org/10.18632/oncotarget.11893

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Abstract

Erik S. Knudsen1,2,3,4, Uthra Balaji1, Elizaveta Freinkman5, Peter McCue6, Agnieszka K. Witkiewicz1,2,3,4,7

1 McDermott Center for Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, USA

2 Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA

3 University of Arizona Cancer Center, University of Arizona, Tucson, AZ, USA

4 Department of Medicine, University of Arizona, Tucson, AZ, USA

5 Whitehead Institute, Massachusetts Institute of Technology, Cambridge, MA, USA

6 Department of Pathology, Thomas Jefferson University, Philadelphia, PA, USA

7 Department of Pathology, University of Arizona, Tucson, AZ, USA

Correspondence to:

Agnieszka K. Witkiewicz, email:

Keywords: pancreatic cancer, tumor metabolism, hypoxia, lactate, metastasis, Pathology Section

Received: June 29, 2016 Accepted: July 13, 2016 Published: September 07, 2016

Abstract

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. The aggressiveness and therapeutic recalcitrance of this malignancy has been attributed to multiple factors including the influence of an active desmoplastic stroma. How the stromal microenvironment of PDAC contributes to the fatal nature of this disease is not well defined. In the analysis of clinical specimens, we observed diverse expression of the hypoxic marker carbonic anhydrase IX and the lactate transporter MCT4 in the stromal compartment. These stromal features were associated with the epithelial to mesenchymal phenotype in PDAC tumor cells, and with shorter patient survival. Cultured cancer-associated fibroblasts (CAFs) derived from primary PDAC exhibited a high basal level of hypoxia inducible factor 1a (HIF1α) that was both required and sufficient to modulate the expression of MCT4. This event was associated with increased transcription and protein synthesis of HIF1α in CAFs relative to PDAC cell lines, while surprisingly the protein turnover rate was equivalent. CAFs utilized glucose predominantly for glycolytic intermediates, whereas glutamine was the preferred metabolite for the TCA cycle. Unlike PDAC cell lines, CAFs were resistant to glucose withdrawal but sensitive to glutamine depletion. Consistent with the lack of reliance on glucose, CAFs could survive the acute depletion of MCT4. In co-culture and xenograft studies CAFs stimulated the invasive potential and metastatic spread of PDAC cell lines through a mechanism dependent on HIF1α and MCT4. Together, these data indicate that stromal metabolic features influence PDAC tumor cells to promote invasiveness and metastatic potential and associate with poor outcome in patients with PDAC.


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