
Arginine Starvation and Docetaxel Induce c-Myc-Driven hENT1 Surface Expression to Overcome Gemcitabine Resistance in ASS1-Negative Tumors.
Authors of this article are:
Prudner BC, Rathore R, Robinson AM, Godec AJ, Chang SF, Hawkins WG, Hirbe AC, Van Tine BA.
A summary of the article is shown below:
PURPOSE: he 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(-) 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(-) tumor cell lines were treated to create LTAT (long term ADI treated) cell lines (ASS1+) and used for drug combination studies. Protein expression of ASS1, dCK, RRM2, E2F1, c-MYC and hENT1 were 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 docetaxel (DTX) to cells treated 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 docetaxel 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.Copyright ©2019, American Association for Cancer Research.
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