Tissue of origin dictates GOT1 dependence and confers synthetic lethality to radiotherapy

Barbara Scott Nelson ,Cristovão M Sousa,Cecilia Cotta‐Ramusino ,Alec C Kimmelman,Lewis C Cantley,Oksana Mashadova,Zachary P Tolstyka,Brandon Nicolay ,Scott Campit,Ting Gao ,Kari Wilder-Romans,Amy L Myers ,Mary A Davis ,Ho‐Joon Lee ,Johanna Ramos,Ilya Kovalenko,Daniel Wahl ,Daniel M Kremer,Sriram Chandrasekaran,John M Asara,Joseph Dresser,Howard C Crawford,Zeribe C Nwosu,Christopher J Halbrook,Lin Lin,Costas A Lyssiotis

doi:10.1186/s40170-019-0202-2

Abstract

BackgroundMetabolic programs in cancer cells are influenced by genotype and the tissue of origin. We have previously shown that central carbon metabolism is rewired in pancreatic ductal adenocarcinoma (PDA) to support proliferation through a glutamate oxaloacetate transaminase 1 (GOT1)-dependent pathway.MethodsWe utilized a doxycycline-inducible shRNA-mediated strategy to knockdown GOT1 in PDA and colorectal cancer (CRC) cell lines and tumor models of similar genotype. These cells were analyzed for the ability to form colonies and tumors to test if tissue type impacted GOT1 dependence. Additionally, the ability of GOT1 to impact the response to chemo- and radiotherapy was assessed. Mechanistically, the associated specimens were examined using a combination of steady-state and stable isotope tracing metabolomics strategies and computational modeling. Statistics were calculated using GraphPad Prism 7. One-way ANOVA was performed for experiments comparing multiple groups with one changing variable. Student’s t test (unpaired, two-tailed) was performed when comparing two groups to each other. Metabolomics data comparing three PDA and three CRC cell lines were analyzed by performing Student’s t test (unpaired, two-tailed) between all PDA metabolites and CRC metabolites.ResultsWhile PDA exhibits profound growth inhibition upon GOT1 knockdown, we found CRC to be insensitive. In PDA, but not CRC, GOT1 inhibition disrupted glycolysis, nucleotide metabolism, and redox homeostasis. These insights were leveraged in PDA, where we demonstrate that radiotherapy potently enhanced the effect of GOT1 inhibition on tumor growth.ConclusionsTaken together, these results illustrate the role of tissue type in dictating metabolic dependencies and provide new insights for targeting metabolism to treat PDA.

Highlights

Metabolic processes are rewired in cancer to facilitate tumor survival and growth[1]
glutamate oxaloacetate transaminase 1 (GOT1) dependence exhibits tissue specificity To determine whether the tissue of origin impacts GOT1 dependence, we compared GOT1 knockdown in a panel of pancreatic ductal adenocarcinoma (PDA) and colorectal cancer (CRC) cell lines that exhibit mutant KRAS and mutant TP53 expression (Fig.1b)
We found that several nodes in nucleotide metabolism were deregulated in PDA cells upon GOT1 inhibition by modeling our metabolomics data with the Recon[1] genome-scale network model[26,27] with dynamic flux analysis (DFA)[28,29] (Extended Fig. 7c,d, Extended Table 1)

Summary

Introduction

Metabolic processes are rewired in cancer to facilitate tumor survival and growth[1]. More recent studies have built upon this work to describe how the cell of origin influences metabolic programs and liabilities in cancer[3,4]. In addition to these intrinsic programs, properties of the tumor microenvironment can influence metabolic programs and liabilities in cancer cells[5]. These studies have revealed that a common set of genetic alterations can lead to different metabolic dependencies contingent on the tissue type, tumor location, and/or properties of the tumor microenvironment[610]

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Results

Conclusion