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Disrupting glutamine metabolic pathways to sensitize gemcitabine-resistant pancreatic cancer.

ABSTRACT: Pancreatic cancer is a lethal disease with poor prognosis. Gemcitabine has been the first line systemic treatment for pancreatic cancer. However, the rapid development of drug resistance has been a major hurdle in gemcitabine therapy leading to unsatisfactory patient outcomes. With the recent renewed understanding of glutamine metabolism involvement in drug resistance and immuno-response, we investigated the anti-tumor effect of a glutamine analog (6-diazo-5-oxo-L-norleucine) as an adjuvant treatment to sensitize chemoresistant pancreatic cancer cells. We demonstrate that disruption of glutamine metabolic pathways improves the efficacy of gemcitabine treatment. Such a disruption induces a cascade of events which impacts glycan biosynthesis through Hexosamine Biosynthesis Pathway (HBP), as well as cellular redox homeostasis, resulting in global changes in protein glycosylation, expression and functional effects. The proteome alterations induced in the resistant cancer cells and the secreted exosomes are intricately associated with the reduction in cell proliferation and the enhancement of cancer cell chemosensitivity. Proteins associated with EGFR signaling, including downstream AKT-mTOR pathways, MAPK pathway, as well as redox enzymes were downregulated in response to disruption of glutamine metabolic pathways.

SUBMITTER: Chen R

PROVIDER: S-EPMC5554139 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Disrupting glutamine metabolic pathways to sensitize gemcitabine-resistant pancreatic cancer.

Chen Ru R Lai Lisa A LA Sullivan Yumi Y Wong Melissa M Wang Lei L Riddell Jonah J Jung Linda L Pillarisetty Venu G VG Brentnall Teresa A TA Pan Sheng S

Scientific reports 20170811 1

Pancreatic cancer is a lethal disease with poor prognosis. Gemcitabine has been the first line systemic treatment for pancreatic cancer. However, the rapid development of drug resistance has been a major hurdle in gemcitabine therapy leading to unsatisfactory patient outcomes. With the recent renewed understanding of glutamine metabolism involvement in drug resistance and immuno-response, we investigated the anti-tumor effect of a glutamine analog (6-diazo-5-oxo-L-norleucine) as an adjuvant trea ...[more]

PMID: 28801576

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Project description:Pancreatic ductal adenocarcinoma (PDAC) is the most prevalent and aggressive form of pancreatic cancer. Gemcitabine (GEM), the first‑line treatment for PDAC, which alleviates symptoms and enhances the quality of life of patients. However, it is prone to lead to the development of drug resistance during treatment. Interferon (IFN)‑γ exhibits antitumor and immunomodulatory properties. The present study aimed to explore the impact of IFN‑γ on the viability, migration and apoptosis of GEM‑resistant pancreatic cancer cells. Firstly, a GEM‑resistant pancreatic cancer cell line, named PANC‑1/GEM, was constructed. Hematoxylin and eosin staining analyzed the cell morphology, whereas reverse transcription‑quantitative PCR (RT‑qPCR) assessed the expression levels of the drug‑resistance genes multidrug resistance‑associated protein (MRP) and breast cancer resistance protein (BCRP). The MTT assay and cell counting techniques were used to determine the appropriate concentration of IFN‑y and its effects on cell viability. The IFN‑γ‑induced apoptosis of PANC‑1/GEM cells was assessed using an Apoptosis Detection Kit, whereas the impact of IFN‑γ on the migration of these cells was evaluated using a wound‑healing assay. The MTT assay revealed a resistance index of 22.4 in the PANC‑1/GEM cell line. RT‑qPCR indicated that, compared with in wild‑type cells, the PANC‑1/GEM resistant strain exhibited lower MRP and higher BCRP mRNA expression levels. The optimal concentration of IFN‑γ for affecting PANC‑1/GEM cells was determined to be 0.3 µg/ml. At this concentration, IFN‑γ induced PANC‑1/GEM cell apoptosis, along with a notable reduction in migration. Following treatment of PANC‑1/GEM cells with IFN‑γ, MRP expression increased whereas BCRP mRNA expression decreased, indicating a reversal in their drug‑resistance gene expression. In conclusion, IFN‑γ exhibited antitumor immune properties by upregulating MRP and downregulating BCRP expression, reversing drug‑resistance gene expression, and reducing cell viability and migration, while promoting apoptosis in PANC‑1/GEM cells. IFN‑γ could potentially serve as a treatment option for patients with GEM‑resistant pancreatic cancer.

Project description:Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer. A factor that contributes to the poor prognosis of the disease is the complex tumor microenvironment (TME). The PDAC TME is composed of excessive fibrosis and desmoplasia, which creates a harsh environment resulting in hypoxia and altered nutrient availability. To promote survival and proliferation in this environment, PDAC cells can reprogram glutamine (Gln) metabolism. Previous studies have demonstrated that PDAC cells use Gln to support proliferation and redox balance. However, earlier attempts to inhibit Gln metabolism using glutaminase inhibitors resulted in rapid metabolic reprogramming and ultimately therapeutic resistance. Here, we hypothesized that using a Gln analogue, such as 6-Diazo-5-oxo-L-norleucine (DON), could broadly target Gln metabolism in PDAC and prevent rapid adaptation. Indeed, DON treatment led to a significant decrease in PDAC proliferation in a dose-dependent manner, as well as a profound reduction of various metabolites involved in central carbon and nucleotide metabolism, suggesting that DON creates a metabolic crisis. In addition, we observed a significant decrease in tumor growth in various in vivo models (syngeneic, immunodeficient) using DRP-104 (sirpiglenastat), a novel pro-drug version of DON that was designed to circumvent DON associated GI toxicity and allow the therapeutic exploration of broad Gln antagonism. Mechanistically, we found that ERK signaling is increased as a compensatory mechanism through the increased activity of receptor tyrosine kinases (RTKs). Combinatorial treatment of DRP-104 and Trametinib (MEK1/2) inhibitor led to a significant increase in survival in a syngeneic model PDAC. Taken together, these pre-clinical results suggest that broadly targeting Gln metabolism could provide a new therapeutic avenue for PDAC and that the combination with an ERK signaling pathway inhibitor could further improve the therapeutic outcome.

Project description:BackgroundAberrant activation NF-kappaB has been proposed as a mechanism of drug resistance in pancreatic cancer. Recently, inhibition of glycogen synthase kinase-3 has been shown to exert anti-tumor effects on pancreatic cancer cells by suppressing NF-kappaB. Consequently, we investigated whether inhibition of GSK-3 sensitizes pancreatic cancer cells to the chemotherapeutic agent gemcitabine.MethodsGSK-3 inhibition was achieved using the pharmacological agent AR-A014418 or siRNA against GSK-3 alpha and beta isoforms. Cytotoxicity was measured using a Sulphorhodamine B assay and clonogenic survival following exposure of six different pancreatic cancer cell lines to a range of doses of either gemcitabine, AR-A014418 or both for 24, 48 and 72 h. We measured protein expression levels by immunoblotting. Basal and TNF-alpha induced activity of NF-kappaB was assessed using a luciferase reporter assay in the presence or absence of GSK-3 inhibition.ResultsGSK-3 inhibition reduced both basal and TNF-alpha induced NF-kappaB luciferase activity. Knockdown of GSK-3 beta reduced nuclear factor kappa B luciferase activity to a greater extent than GSK-3 alpha, and the greatest effect was seen with dual knockdown of both GSK-3 isoforms. GSK-3 inhibition also resulted in reduction of the NF-kappaB target proteins XIAP, Bcl-XL, and cyclin D1, associated with growth inhibition and decreased clonogenic survival. In all cell lines, treatment with either AR-A014418, or gemcitabine led to growth inhibition in a dose- and time-dependent manner. However, with the exception of PANC-1 where drug synergy occurred with some dose schedules, the inhibitory effect of combined drug treatment was additive, sub-additive, or even antagonistic.ConclusionGSK-3 inhibition has anticancer effects against pancreatic cancer cells with a range of genetic backgrounds associated with disruption of NF-kappaB, but does not significantly sensitize these cells to the standard chemotherapy agent gemcitabine. This lack of synergy might be context or cell line dependent, but could also be explained on the basis that although NF-kappaB is an important mediator of pancreatic cancer cell survival, it plays a minor role in gemcitabine resistance. Further work is needed to understand the mechanisms of this effect, including the potential for rational combination of GSK3 inhibitors with other targeted agents for the treatment of pancreatic cancer.

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Disrupting glutamine metabolic pathways to sensitize gemcitabine-resistant pancreatic cancer.

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Disrupting glutamine metabolic pathways to sensitize gemcitabine-resistant pancreatic cancer.

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