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Drug Resistance Updates : Reviews and... Mar 2023BRCA2 is a well-established cancer driver in several human malignancies. While the remarkable success of PARP inhibitors proved the clinical potential of targeting BRCA...
BRCA2 is a well-established cancer driver in several human malignancies. While the remarkable success of PARP inhibitors proved the clinical potential of targeting BRCA deficiencies, the emergence of resistance mechanisms underscores the importance of seeking novel Synthetic Lethal (SL) targets for future drug development efforts. In this work, we performed a BRCA2-centric SL screen with a collection of plant-derived compounds from South America. We identified the steroidal alkaloid Solanocapsine as a selective SL inducer, and we were able to substantially increase its potency by deriving multiple analogs. The use of two complementary chemoproteomic approaches led to the identification of the nucleotide salvage pathway enzyme deoxycytidine kinase (dCK) as Solanocapsine's target responsible for its BRCA2-linked SL induction. Additional confirmatory evidence was obtained by using the highly specific dCK inhibitor (DI-87), which induces SL in multiple BRCA2-deficient and KO contexts. Interestingly, dCK-induced SL is mechanistically different from the one induced by PARP inhibitors. dCK inhibition generates substantially lower levels of DNA damage, and cytotoxic phenotypes are associated exclusively with mitosis, thus suggesting that the fine-tuning of nucleotide supply in mitosis is critical for the survival of BRCA2-deficient cells. Moreover, by using a xenograft model of contralateral tumors, we show that dCK impairment suffices to trigger SL in-vivo. Taken together, our findings unveil dCK as a promising new target for BRCA2-deficient cancers, thus setting the ground for future therapeutic alternatives to PARP inhibitors.
Topics: Humans; Deoxycytidine Kinase; Poly(ADP-ribose) Polymerase Inhibitors; Antineoplastic Agents; Nucleotides; Protein Kinase Inhibitors; BRCA2 Protein
PubMed: 36706533
DOI: 10.1016/j.drup.2023.100932 -
Acta Haematologica 2021Resistance to cytarabine is an important cause of therapy failure in persons with acute myeloid leukemia (AML). Deoxycytidine kinase, encoded by DCK, catalyzes...
Resistance to cytarabine is an important cause of therapy failure in persons with acute myeloid leukemia (AML). Deoxycytidine kinase, encoded by DCK, catalyzes phosphorylation of cytarabine to cytarabine monophosphate, a necessary step for eventual incorporation of cytarabine triphosphate into DNA and for clinical efficacy. Whether DCK mutations make AML cells resistant to cytarabine is controversial. We studied DCK mutations and messenger RNA (mRNA) concentrations in leukemia cells from 10 subjects with AML who received cytarabine-based therapy and relapsed and in 2 artificially induced cytarabine-resistant AML cell lines. DCK mutations were detected in 4 subjects with AML relapsing after achieving a complete remission and receiving high-dose cytarabine postremission therapy. Most mutations were in exons 4-6 and were not present before therapy. DCK was also mutated in cytarabine-resistant but not parental AML cell lines. DCK mRNA concentrations were significantly decreased in cytarabine-resistant K562 and SHI-1 cells compared with cytarabine-sensitive parental cells. Mutation frequency of DCK and mRNA concentration did not correlate with the extent of cytarabine resistance indicating other factors operate. Overexpression of wild-type DCK restored cytarabine sensitivity to previously resistant leukemia cell lines. Our data contribute to the understanding of cytarabine resistance in persons with AML.
Topics: Cytarabine; Deoxycytidine Kinase; Drug Resistance, Neoplasm; Humans; K562 Cells; Leukemia, Myeloid, Acute; Mutation; Neoplasm Proteins; RNA, Messenger; RNA, Neoplasm
PubMed: 33626530
DOI: 10.1159/000513696 -
Immunology Jan 2023Multiple sclerosis (MS) is an autoimmune disease driven by lymphocyte activation against myelin autoantigens in the central nervous system leading to demyelination and...
Multiple sclerosis (MS) is an autoimmune disease driven by lymphocyte activation against myelin autoantigens in the central nervous system leading to demyelination and neurodegeneration. The deoxyribonucleoside salvage pathway with the rate-limiting enzyme deoxycytidine kinase (dCK) captures extracellular deoxyribonucleosides for use in intracellular deoxyribonucleotide metabolism. Previous studies have shown that deoxyribonucleoside salvage activity is enriched in lymphocytes and required for early lymphocyte development. However, specific roles for the deoxyribonucleoside salvage pathway and dCK in autoimmune diseases such as MS are unknown. Here we demonstrate that dCK activity is necessary for the development of clinical symptoms in the MOG and MOG experimental autoimmune encephalomyelitis (EAE) mouse models of MS. During EAE disease, deoxyribonucleoside salvage activity is elevated in the spleen and lymph nodes. Targeting dCK with the small molecule dCK inhibitor TRE-515 limits disease severity when treatments are started at disease induction or when symptoms first appear. EAE mice treated with TRE-515 have significantly fewer infiltrating leukocytes in the spinal cord, and TRE-515 blocks activation-induced B and T cell proliferation and MOG -specific T cell expansion without affecting innate immune cells or naïve T and B cell populations. Our results demonstrate that targeting dCK limits symptoms in EAE mice and suggest that dCK activity is required for MOG -specific lymphocyte activation-induced proliferation.
Topics: Animals; Mice; Multiple Sclerosis; Deoxycytidine Kinase; Encephalomyelitis, Autoimmune, Experimental; Lymphocytes; Disease Models, Animal; Mice, Inbred C57BL
PubMed: 35986643
DOI: 10.1111/imm.13569 -
Cell Death & Disease Feb 2024Pancreatic ductal adenocarcinoma (PDAC) is considered one of the most lethal forms of cancer. Although in the last decade, an increase in 5-year patient survival has...
Pancreatic ductal adenocarcinoma (PDAC) is considered one of the most lethal forms of cancer. Although in the last decade, an increase in 5-year patient survival has been observed, the mortality rate remains high. As a first-line treatment for PDAC, gemcitabine alone or in combination (gemcitabine plus paclitaxel) has been used; however, drug resistance to this regimen is a growing issue. In our previous study, we reported MYC/glutamine dependency as a therapeutic target in gemcitabine-resistant PDAC secondary to deoxycytidine kinase (DCK) inactivation. Moreover, enrichment of oxidative phosphorylation (OXPHOS)-associated genes was a common property shared by PDAC cell lines, and patient clinical samples coupled with low DCK expression was also demonstrated, which implicates DCK in cancer metabolism. In this article, we reveal that the expression of most genes encoding mitochondrial complexes is remarkably upregulated in PDAC patients with low DCK expression. The DCK-knockout (DCK KO) CFPAC-1 PDAC cell line model reiterated this observation. Particularly, OXPHOS was functionally enhanced in DCK KO cells as shown by a higher oxygen consumption rate and mitochondrial ATP production. Electron microscopic observations revealed abnormal mitochondrial morphology in DCK KO cells. Furthermore, DCK inactivation exhibited reactive oxygen species (ROS) reduction accompanied with ROS-scavenging gene activation, such as SOD1 and SOD2. SOD2 inhibition in DCK KO cells clearly induced cell growth suppression. In combination with increased anti-apoptotic gene BCL2 expression in DCK KO cells, we finally reveal that venetoclax and a mitochondrial complex I inhibitor are therapeutically efficacious for DCK-inactivated CFPAC-1 cells in in vitro and xenograft models. Hence, our work provides insight into inhibition of mitochondrial metabolism as a novel therapeutic approach to overcome DCK inactivation-mediated gemcitabine resistance in PDAC patient treatment.
Topics: Humans; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Deoxycytidine; Deoxycytidine Kinase; Drug Resistance, Neoplasm; Gemcitabine; Paclitaxel; Pancreatic Neoplasms; Reactive Oxygen Species
PubMed: 38346958
DOI: 10.1038/s41419-024-06531-x -
Cancer Research May 2019Deoxycytidine kinase (DCK) is a key enzyme for the activation of a broad spectrum of nucleoside-based chemotherapy drugs (e.g., gemcitabine); low DCK activity is one of...
Deoxycytidine kinase (DCK) is a key enzyme for the activation of a broad spectrum of nucleoside-based chemotherapy drugs (e.g., gemcitabine); low DCK activity is one of the most important causes of cancer drug-resistance. Noninvasive imaging methods that can quantify DCK activity are invaluable for assessing tumor resistance and predicting treatment efficacy. Here we developed a "natural" MRI approach to detect DCK activity using its natural substrate deoxycytidine (dC) as the imaging probe, which can be detected directly by chemical exchange saturation transfer (CEST) MRI without any synthetic labeling. CEST MRI contrast of dC and its phosphorylated form, dCTP, successfully discriminated DCK activity in two mouse leukemia cell lines with different DCK expression. This dC-enhanced CEST MRI in xenograft leukemic cancer mouse models demonstrated that DCK(+) tumors have a distinctive dynamic CEST contrast enhancement and a significantly higher CEST contrast than DCK(-) tumors (AUC = 0.47 ± 0.25 and 0.20 ± 0.13, respectively; = 0.026, paired Student test, = 4) at 1 hour after the injection of dC. dC-enhanced CEST contrast also correlated well with tumor responses to gemcitabine treatment. This study demonstrates a novel MR molecular imaging approach for predicting cancer resistance using natural, nonradioactive, nonmetallic, and clinically available agents. This method has great potential for pursuing personalized chemotherapy by stratifying patients with different DCK activity. SIGNIFICANCE: A new molecular MRI method that detects deoxycytidine kinase activity using its natural substrate deoxycytidine has great translational potential for clinical assessment of tumor resistance and prediction of treatment efficacy.
Topics: Animals; Cell Line, Tumor; Deoxycytidine; Deoxycytidine Kinase; Female; Heterografts; Leukemia; Magnetic Resonance Imaging; Mice; Mice, Inbred NOD; Mice, SCID; Substrate Specificity
PubMed: 30940660
DOI: 10.1158/0008-5472.CAN-18-3565 -
Pharmacy World & Science : PWS Apr 1994Deoxycytidine kinase is an enzyme required for the activation of, for example, cytarabine, the most widely used agent for the chemotherapy of haematological... (Review)
Review
Deoxycytidine kinase is an enzyme required for the activation of, for example, cytarabine, the most widely used agent for the chemotherapy of haematological malignancies. However, deoxycytidine kinase also plays an important role in the activation of several new agents used in the treatment of leukaemia, such as cladribine. Recently, a new cytidine analogue, gemcitabine, has shown impressive activity as a single agent against several solid malignancies (ovarian cancer, non-small cell lung cancer), demonstrating that in solid tumours deoxycytidine kinase can be an important target for the activation of antimetabolites. Studies on the regulation of deoxycytidine kinase have shown that the enzyme has a complicated regulation (feedback inhibition by the product and regulation by ribonucleotides). Modulation of deoxycytidine kinase activity has already been shown to be an effective way to improve the effect of cytarabine and will probably be a target for new therapies.
Topics: Animals; Antimetabolites, Antineoplastic; Biotransformation; Cytarabine; Deoxycytidine Kinase; Drug Resistance; Humans; Neoplasms
PubMed: 7980770
DOI: 10.1007/BF01880661 -
Methods in Molecular Biology (Clifton,... 2019Suicide transgenes encode proteins that are either capable of activating specific prodrugs into cytotoxic antimetabolites that can trigger cancer cell apoptosis or are...
Suicide transgenes encode proteins that are either capable of activating specific prodrugs into cytotoxic antimetabolites that can trigger cancer cell apoptosis or are capable of directly inducing apoptosis. Suicide gene therapy of cancer (SGTC) involves the targeted or localized delivery of suicide transgene sequences into tumor cells by means of various gene delivery vehicles. SGTC that operates via the potentiation of small-molecule pharmacologic agents can elicit the elimination of cancer cells within a tumor beyond only those cells successfully transduced. Such "bystander effects ", typically mediated by the spread of activated cytotoxic antimetabolites from the transduced cells expressing the suicide transgene to adjacent cells in the tumor, can lead to a significant reduction of the tumor mass without the requirement of transduction of a high percentage of cells within the tumor. The spread of activated cytotoxic molecules to adjacent cells is mediated primarily by diffusion and normally involves gap junctional intercellular communications (GJIC). We have developed a novel SGTC system based on viral vector-mediated delivery of an engineered variant of human deoxycytidine kinase (dCK), which is capable of phosphorylating uridine- and thymidine-based nucleoside analogues that are not substrates for wild-type dCK, such as bromovinyl deoxyuridine (BVdU) and L-deoxythymidine (LdT). Since our dCK-based SGTC system is capable of mediating strong bystander cell killing, it holds promise for clinical translation. In this chapter, we detail the key procedures for the preparation of recombinant lentivectors for the delivery of engineered dCK, transduction of tumor cells, and evaluation of bystander cell killing effects in vitro and in vivo.
Topics: Animals; Apoptosis; Bromodeoxyuridine; Bystander Effect; Cell Line, Tumor; Deoxycytidine Kinase; Genes, Transgenic, Suicide; Genetic Therapy; HEK293 Cells; Humans; Male; Mice; Mice, SCID; Neoplasms; Prodrugs; Thymidine
PubMed: 30539536
DOI: 10.1007/978-1-4939-8922-5_12 -
European Journal of Haematology Sep 2016Leukaemia initiating cells reside within specialised niches in the bone marrow where they undergo complex interactions with different stromal cell types. The bone marrow...
OBJECTIVES
Leukaemia initiating cells reside within specialised niches in the bone marrow where they undergo complex interactions with different stromal cell types. The bone marrow niche is characterised by a low oxygen content resulting in high expression of hypoxia-inducible factor 1 α in leukaemic cells conferring a negative prognosis to patients with acute myeloid leukaemia (AML).
METHODS AND RESULTS
In the current study, we investigated the impact of hypoxic vs. normoxic conditions on the sensitivity of AML cell lines and primary AML blasts to cytarabine. AML cells cultured under 6% oxygen were significantly more resistant against cytarabine compared to cells cultured under normoxic conditions in proliferation and colony-formation assays. Interestingly upon cultivation under hypoxia, the expression of the cytarabine-activating enzyme deoxycytidine kinase was downregulated in all analysed AML cell lines and primary AML samples representing a possible mechanism for resistance to chemotherapy. Furthermore, the downregulation of deoxycytidine kinase could be associated with hypoxia-inducible factor 1 α as treatment with its inhibitor BAY87-2243 hampered the downregulation of deoxycytidine kinase expression under hypoxic conditions.
CONCLUSIONS
In conclusion, our data reveal that hypoxia-induced downregulation of deoxycytidine kinase represents one stroma-cell-independent mechanism of drug resistance to cytarabine in acute myeloid leukaemia.
Topics: Antimetabolites, Antineoplastic; Cell Line, Tumor; Cell Proliferation; Cytarabine; Deoxycytidine Kinase; Down-Regulation; Drug Resistance, Neoplasm; Gene Expression; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Leukemia, Myeloid, Acute; Neoplastic Stem Cells
PubMed: 26613208
DOI: 10.1111/ejh.12711 -
Molecular Cancer Research : MCR May 2023Pancreatic ductal adenocarcinoma (PDAC) is one of the most life-threatening malignancies. Although the deoxycytidine analog gemcitabine has been used as the first-line...
UNLABELLED
Pancreatic ductal adenocarcinoma (PDAC) is one of the most life-threatening malignancies. Although the deoxycytidine analog gemcitabine has been used as the first-line treatment for PDAC, the primary clinical challenge arises because of an eventual acquisition of resistance. Therefore, it is crucial to elucidate the mechanisms underlying gemcitabine resistance to improve treatment efficacy. To investigate potential genes whose inactivation confers gemcitabine resistance, we performed CRISPR knockout (KO) library screening. We found that deoxycytidine kinase (DCK) deficiency is the primary mechanism of gemcitabine resistance, and the inactivation of CRYBA2, DMBX1, CROT, and CD36 slightly conferred gemcitabine resistance. In particular, gene expression analysis revealed that DCK KO cells displayed a significant enrichment of genes associated with MYC targets, folate/one-carbon metabolism and glutamine metabolism pathways. Evidently, chemically targeting each of these pathways significantly reduced the survival of DCK KO cells. Moreover, the pathways enriched in DCK KO cells represented a trend similar to those in PDAC cell lines and samples of patients with PDAC with low DCK expression. We further observed that short-term treatment of parental CFPAC-1 cells with gemcitabine induces the expression of several genes, which promote synthesis and transport of glutamine in a dose-dependent manner, which suggests glutamine availability as a potential mechanism of escaping drug toxicity in an initial response for survival. Thus, our findings provide insights into novel therapeutic approaches for gemcitabine-resistant PDAC and emphasize the involvement of glutamine metabolism in drug-tolerant persister cells.
IMPLICATIONS
Our study revealed the key pathways involved in gemcitabine resistance in PDAC, thus providing potential therapeutic strategies.
Topics: Humans; Antimetabolites, Antineoplastic; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Deoxycytidine; Deoxycytidine Kinase; Drug Resistance, Neoplasm; Gemcitabine; Glutamine; Pancreatic Neoplasms
PubMed: 36757299
DOI: 10.1158/1541-7786.MCR-22-0554 -
PloS One 2014Efficient and adequate generation of deoxyribonucleotides is critical to successful DNA repair. We show that ataxia telangiectasia mutated (ATM) integrates the DNA...
Efficient and adequate generation of deoxyribonucleotides is critical to successful DNA repair. We show that ataxia telangiectasia mutated (ATM) integrates the DNA damage response with DNA metabolism by regulating the salvage of deoxyribonucleosides. Specifically, ATM phosphorylates and activates deoxycytidine kinase (dCK) at serine 74 in response to ionizing radiation (IR). Activation of dCK shifts its substrate specificity toward deoxycytidine, increases intracellular dCTP pools post IR, and enhances the rate of DNA repair. Mutation of a single serine 74 residue has profound effects on murine T and B lymphocyte development, suggesting that post-translational regulation of dCK may be important in maintaining genomic stability during hematopoiesis. Using [(18)F]-FAC, a dCK-specific positron emission tomography (PET) probe, we visualized and quantified dCK activation in tumor xenografts after IR, indicating that dCK activation could serve as a biomarker for ATM function and DNA damage response in vivo. In addition, dCK-deficient leukemia cell lines and murine embryonic fibroblasts exhibited increased sensitivity to IR, indicating that pharmacologic inhibition of dCK may be an effective radiosensitization strategy.
Topics: Animals; Ataxia Telangiectasia Mutated Proteins; B-Lymphocytes; Cell Line, Tumor; DNA Damage; DNA Repair; Deoxycytidine; Deoxycytidine Kinase; Deoxyribonucleosides; Genomic Instability; Hematopoiesis; Humans; Mice; Mice, Inbred BALB C; Mice, Knockout; Mutagenesis, Site-Directed; Phosphorylation; Protein Processing, Post-Translational; Substrate Specificity; T-Lymphocytes
PubMed: 25101980
DOI: 10.1371/journal.pone.0104125