ku-55933 and Neoplasms

Personalized medicine and therapies represent the goal of modern medicine, as drug discovery strives to move away from one-cure-for-all and makes use of the various targets and biomarkers within differing disease areas. This approach, especially in oncology, is often undermined when the cells make use of alternative survival pathways. As such, acquired resistance is unfortunately common. In order to combat this phenomenon, synthetic lethality is being investigated, making use of existing genetic fragilities within the cancer cell. This Perspective highlights exciting targets within synthetic lethality, (PARP, ATR, ATM, DNA-PKcs, WEE1, CDK12, RAD51, RAD52, and PD-1) and discusses the medicinal chemistry programs being used to interrogate them, the challenges these programs face, and what the future holds for this promising field.

Topics: Ataxia Telangiectasia Mutated Proteins; Cell Cycle Proteins; Cyclin-Dependent Kinases; DNA-Activated Protein Kinase; Genes, BRCA2; Humans; Neoplasms; Poly(ADP-ribose) Polymerases; Precision Medicine; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Rad51 Recombinase; Synthetic Lethal Mutations

Modulation of DNA repair pathways in oncology has been an area of intense interest in the last decade, not least as a consequence of the promising clinical activity of poly(ADP-ribose) polymerase (PARP) inhibitors. In this review article, we highlight inhibitors of the phosphatidylinositol 3-kinase related kinase (PIKK) family as of potential interest in the treatment of cancer, both in combination with DNA-damaging therapies and as stand-alone agents.

Topics: Animals; Ataxia Telangiectasia Mutated Proteins; Cell Cycle Proteins; DNA; DNA Repair; DNA-Activated Protein Kinase; DNA-Binding Proteins; Humans; Models, Molecular; Neoplasms; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Tumor Suppressor Proteins

DNA-damaging agents have a central role in non-surgical cancer treatment. The balance between DNA damage and repair determines the final therapeutic consequences. An elevated DNA-repair capacity in tumor cells leads to drug or radiation resistance and severely limits the efficacy of these agents. Interference with DNA repair has emerged as an important approach in combination therapy against cancer. Anticancer targets in DNA-repair systems have emerged, against which several small-molecule compounds are currently undergoing clinical trials.

Topics: Animals; Antineoplastic Agents; Ataxia Telangiectasia Mutated Proteins; Cell Cycle Proteins; DNA Damage; DNA Repair; DNA-Binding Proteins; DNA, Neoplasm; Drug Resistance, Neoplasm; Guanine; Humans; Morpholines; Neoplasms; O(6)-Methylguanine-DNA Methyltransferase; Poly(ADP-ribose) Polymerases; Protein Serine-Threonine Kinases; Pyrones; Quinazolines; Signal Transduction; Tumor Suppressor Proteins

Ataxia-telangiectasia mutated (ATM) kinase is a serine/threonine protein kinase and plays a key role in DNA double-strand breaks repair. Thus, ATM is considered a promising target for radiotherapy and chemotherapy sensitizing. Herein, we report the discovery of ATM agonist A22 and inhibitor A41 by computational methods and further biological evaluation. Among them, A22 exhibited low cytotoxicity in vitro and might serve as a useful tool for ATM research. Moreover, we firstly proved that ATM inhibitors could sensitize Irinotecan and Etoposide in a time-dependent manner on MCF-7 and SW480 cells, antagonism in a short period treatment while synergy at a long-term treatment and ATM agonist worked in an opposite way of ATM inhibitors. Further mechanism study demonstrated that the antagonism effect of ATM inhibitors with chemotherapeutic agents in a short period was resulting from inhibiting the p53/p21 axis to accelerate G1/S phase cell-cycle transition and promote cell survival. Additionally, A41 displayed antitumor effects combined with a chemotherapeutic drug in the SW480 xenograft model, indicating that A41 is a promising ATM inhibitor, which could increase the antitumor effect of chemotherapeutic drugs in vivo. All in all, these findings will guide the combination of ATM inhibitors with chemotherapeutic agents in further preclinical and clinical studies.

Topics: Ataxia Telangiectasia; Ataxia Telangiectasia Mutated Proteins; Cell Cycle Proteins; Cell Line, Tumor; DNA-Binding Proteins; Humans; Neoplasms; Phosphorylation; Protein Serine-Threonine Kinases

Human checkpoint kinase ataxia telangiectasia-mutated (ATM) plays a key role in initiation of the DNA damage response following DNA double-strand breaks. ATM inhibition is a promising approach in cancer therapy, but, so far, detailed insights into the binding modes of known ATM inhibitors have been hampered due to the lack of high-resolution ATM structures. Using cryo-EM, we have determined the structure of human ATM to an overall resolution sufficient to build a near-complete atomic model and identify two hitherto unknown zinc-binding motifs. We determined the structure of the kinase domain bound to ATPγS and to the ATM inhibitors KU-55933 and M4076 at 2.8 Å, 2.8 Å and 3.0 Å resolution, respectively. The mode of action and selectivity of the ATM inhibitors can be explained by structural comparison and provide a framework for structure-based drug design.

Topics: Adenosine Triphosphate; Ataxia Telangiectasia Mutated Proteins; Binding Sites; Catalytic Domain; Cryoelectron Microscopy; Humans; Models, Molecular; Morpholines; Mutation; Neoplasms; Protein Conformation; Protein Kinase Inhibitors; Pyrones

NK cell exhaustion (NCE) due to sustained proliferation results in impaired NK cell function with loss of cytokine production and lytic activity. Using murine models of chronic NK cell stimulation, we have identified a phenotypic signature of NCE characterized by up-regulation of the terminal differentiation marker KLRG1 and by down-regulation of eomesodermin and the activating receptor NKG2D. Chronic stimulation of mice lacking NKG2D resulted in minimized NCE compared to control mice, thus identifying NKG2D as a crucial mediator of NCE. NKG2D internalization and downregulations on NK cells has been previously observed in the presence of tumor cells with high expression of NKG2D ligands (NKG2DL) due to the activation of the DNA damage repair pathways. Interestingly, our study revealed that during NK cell activation there is an increase of MULT1, and NKG2DL, that correlates with an induction of DNA damage. Treatment with the ATM DNA damage repair pathway inhibitor KU55933 (KU) during activation reduced NCE by improving expression of activation markers and genes involved in cell survival, by sustaining NKG2D expression and by preserving cell functionality. Importantly, NK cells expanded ex vivo in the presence of KU displayed increased anti-tumor efficacy in both NKG2D-dependent and -independent mouse models. Collectively, these data demonstrate that NCE is caused by DNA damage and regulated, at least in part, by NKG2D. Further, the prevention of NCE is a promising strategy to improve NK cell-based immunotherapy.

Topics: Animals; Cell Differentiation; Cell Line, Tumor; Cell Proliferation; Cell Survival; Disease Models, Animal; DNA Damage; DNA Repair; Female; Histocompatibility Antigens Class I; Humans; Killer Cells, Natural; Lymphocyte Activation; Membrane Proteins; Mice; Mice, Knockout; Morpholines; Neoplasms; NK Cell Lectin-Like Receptor Subfamily K; Pyrones

Autophagy is a degradative process in which cellular organelles and proteins are recycled to restore homeostasis and cellular metabolism. Autophagy can be either a prosurvival or a prodeath process and remains one of the most fundamental processes for cell vitality. Thus autophagy modulation is an important approach for reinforcement anticancer therapeutics. Earlier we have demonstrated that recombinant analog of human milk protein lactaptin (RL2) induced apoptosis of various cultured cancer cells and activated lipidation of microtubule-associated protein 1 light chain 3 (LC3). In this study we investigated whether autophagy inhibitors-chloroquine (CQ), Ku55933 (Ku), and 3-methyladenine (3MA)-or inducer-rapamycin (Rap)-can enhance cytotoxic activity of lactaptin analog in cancer cells and its anticancer activity in the mice model. Western Blot analysis revealed that RL2 induced short-term autophagy in MDA-MB-231 and MCF-7 cells at early stages of incubation and that these data were confirmed by the transmission electron microscopy of autophagosome/autophagolysosome formation. RL2 stimulates reactive oxygen species (ROS) production, autophagosomes accumulation, upregulation of ATG5 with processing of LC3I to LC3II, and downregulation of p62/sequestosome 1 (p62). We have shown that autophagy modulators, CQ, Ku, and Rap, synergistically increased cytotoxicity of RL2, and RL2 with CQ induced autophagic cell death. In addition, CQ, Ku, and Rap in combination with RL2 decreased activity of lysosomal protease Cathepsin D. More importantly, combining RL2 with CQ, we improved antitumor effect in mice. Detected synergistic cytotoxic effects of both types of autophagy regulators, inhibitors, and inducers with RL2 against cancer cells allow us to believe that these combinations can be a basis for the new anticancer approach. Finally, we suppose that CQ and Rap promoting of short-term RL2-induced autophagy interlinks with final autophagic cell death.

Topics: Adenine; Animals; Antineoplastic Agents; Apoptosis; Autophagy; Caseins; Cathepsin D; Cell Death; Cell Line, Tumor; Cell Proliferation; Chloroquine; Humans; Lysosomes; MCF-7 Cells; Mice; Microtubule-Associated Proteins; Morpholines; Neoplasms; Pyrones; Reactive Oxygen Species; Sequestosome-1 Protein

Radiotherapy is a key component of cancer treatment. Because of its importance, there has been high interest in developing agents and strategies to further improve the therapeutic index of radiotherapy. DNA double-strand repair inhibitors (DSBRIs) are among the most promising agents to improve radiotherapy. However, their clinical translation has been limited by their potential toxicity to normal tissue. Recent advances in nanomedicine offer an opportunity to overcome this limitation. In this study, we aim to demonstrate the proof of principle by developing and evaluating nanoparticle (NP) formulations of KU55933, a DSBRI. We engineered a NP formulation of KU55933 using nanoprecipitation method with different lipid polymer nanoparticle formulation. NP KU55933 using PLGA formulation has the best loading efficacy as well as prolonged drug release profile. We demonstrated that NP KU55933 is a potent radiosensitizer in vitro using clonogenic assay and is more effective as a radiosensitizer than free KU55933 in vivo using mouse xenograft models of non-small cell lung cancer (NSCLC). Western blots and immunofluorescence showed NP KU55933 exhibited more prolonged inhibition of DNA repair pathway. In addition, NP KU55933 leads to lower skin toxicity than KU55933. Our study supports further investigations using NP to deliver DSBRIs to improve cancer radiotherapy treatment.

Topics: Animals; Carcinoma, Non-Small-Cell Lung; DNA Breaks, Double-Stranded; Drug Carriers; Drug Delivery Systems; Humans; Lactic Acid; Lipids; Lung Neoplasms; Male; Mice; Mice, Nude; Mice, SCID; Microscopy, Fluorescence; Morpholines; Nanomedicine; Nanoparticles; Neoplasm Transplantation; Neoplasms; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Polymers; Pyrones; Radiation-Sensitizing Agents; Radiotherapy

Aberrant activation of Akt plays a pivotal role in cancer development. ATM, a protein deficient in patients with ataxia-telangiectasia disease, is traditionally considered as a nuclear protein kinase that functions as a signal transducer in response to DNA damage. It has recently been shown that ATM is also a cytoplasmic protein that mediates the full activation of Akt in response to insulin. Our study shows that a specific ATM inhibitor, KU-55933, blocks the phosphorylation of Akt induced by insulin and insulin-like growth factor I in cancer cells that exhibit abnormal Akt activity. Moreover, KU-55933 inhibits cancer cell proliferation by inducing G(1) cell cycle arrest. It does so through the downregulation of the synthesis of cyclin D1, a protein known to be elevated in a variety of tumors. In addition, KU-55933 treatment during serum starvation triggers apoptosis in these cancer cells. Our results suggest that KU-55933 may be a novel chemotherapeutic agent targeting cancer resistant to traditional chemotherapy or immunotherapy due to aberrant activation of Akt. Furthermore, KU-55933 completely abrogates rapamycin-induced feedback activation of Akt. Combination of KU-55933 and rapamycin not only induces apoptosis, which is not seen in cancer cells treated only with rapamycin, but also shows better efficacy in inhibiting cancer cell proliferation than each drug alone. Therefore, combining KU-55933 with rapamycin may provide a highly effective approach for improving mammalian target of rapamycin-targeted anticancer therapy that is currently hindered by rapamycin-induced feedback activation of Akt.

Topics: Adaptor Proteins, Signal Transducing; Animals; Apoptosis; Ataxia Telangiectasia Mutated Proteins; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Cyclin D1; DNA-Binding Proteins; Down-Regulation; Drug Screening Assays, Antitumor; Drug Synergism; Enzyme Activation; Fibroblasts; G1 Phase; Humans; Insulin; Intercellular Signaling Peptides and Proteins; Mice; Morpholines; Neoplasms; Peptide Chain Initiation, Translational; Phosphoproteins; Phosphorylation; Protein Kinase Inhibitors; Protein Processing, Post-Translational; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; Pyrones; Sirolimus; Transcription, Genetic; Tumor Suppressor Proteins