Arginine Starvation and Docetaxel Induce c-Myc–Driven hENT1 Surface Expression to Overcome Gemcitabine Resistance in ASS1-Negative Tumors

Abstract

Purpose: The response to acute and long-term arginine starvation results in a conditional adaptive metabolic reprogramming that can be harnessed for therapeutic opportunities in ASS1-negative tumors. Here, we investigate the underlying biology of priming ASS1 À tumors with arginine deiminase (ADI-PEG20) before treatment with gemcitabine (GEM) and docetaxel (DTX) in sarcoma, pancreatic cancer, and melanoma cell lines.Experimental Design: ASS1 À tumor cell lines were treated to create LTAT (long-term ADI treated) cell lines (ASS1 þ ) and used for drug combination studies. Protein expression of ASS1, dCK, RRM2, E2F1, c-MYC, and hENT1 was measured. c-MYC activity was determined, live-cell immunofluorescent studies for hENT1, uptake assays of FITC-cytosine probe, and rescue studies with a c-MYC inhibitor were all determined in the presence or absence of the ADI-PEG20:GEM:DTX.Results: In examining modulations within the pyrimidine pathway, we identified that the addition of DTX to cells treated with ADI-PEG20 resulted in translocation of stabilized c-Myc to the nucleus. This resulted in an increase of hENT1 cell-surface expression and rendered the cells susceptible to GEM. In vivo studies demonstrate that the combination of ADI-PEG20:GEM: DTX was optimal for tumor growth inhibition, providing the preclinical mechanism and justification for the ongoing clinical trial of ADI-PEG20, GEM, and DTX in sarcoma.Conclusions: The priming of tumors with ADI-PEG20 and DTX results in the stabilization of c-MYC potentiating the effect of GEM treatment via an increase in hENT1 expression. This finding is applicable to ASS1-deficient cancers that are currently treated with GEM.

Systems level profiling of arginine starvation reveals MYC and ERK adaptive metabolic reprogramming

“…Due to the high adaptability of tumor metabolism, most metabolically active drugs are not effective when used as monoagents 15 . However, investigations of the metabolic reprogramming that ASS1-negative tumors undergo as they re-express ASS1 have revealed additional vulnerabilities in ADI-PEG20 sensitive sarcomas 7,8,15,17 . To date, many of these studies have relied upon metabolomic and genetic stratigies to understand the development of resistance to ADI-PEG20 treatment in ASS1 negative tumors.…”

Systems level profiling of arginine starvation reveals MYC and ERK adaptive metabolic reprogramming

“…6A). Myc is stabilized in SKLMS1 cells upon ADI-PEG20 treatment and the cMyc-Max heterodimerization inhibitor 10058-F4 blocks ADI-driven resistance consistent with this regulatory model (Prudner et al , 2019b). Network analysis indicated that Myc and Max are driven by upstream activation of ERK1/2 (MAPK1/3, Fig.…”

“…Many cancers are arginine auxotrophic due to silencing of ASS1 and/or argininosuccinate lyase (Keshet et al , 2018). These tumors are sensitive to ADI-PEG20, which converts arginine to citrulline (Przystal et al , 2018), but ultimately tumors develop resistance through re-expression of ASS1, metabolic reprogramming (Kremer et al , 2017a), and myc stabilization (Prudner et al , 2019b). In order to more broadly understand how cells develop resistance to arginine starvation, we focused on identifying the proteomic adaptations that facilitate metabolic reprogramming, and ultimately escape, in ADI-PEG20 sensitive cells,…”

“…As our understanding of drug development in this field has progressed, it has become clear that most agents will fail as monoagents due to the adaptability of tumor metabolism (Kremer et al , 2017b). By understanding the metabolic reprogramming that ASS1-negative tumors undergo as they re-express ASS1, additional vulnerabilities have been identified in sarcomas (Kobayashi et al , 2010; Prudner et al , 2019a; Kremer et al , 2017b; Huang et al , 2013).…”

“…The mechanisms of developing resistance to arginine starvation in sarcomas have been partially defined, and include stabilization of nuclear cMyc (Prudner et al , 2019b), and increased glutamine anaplerosis in order to produce aspartate (Kremer et al , 2017a). In addition, others have examined mechanisms of ASS1 re-expression (Tsai et al , 2017; Long et al , 2017) and Deptor regulation (Ohshima et al , 2017).…”