piperidines and vacquinol-1

Recent research developments have revealed that caspase-dependent apoptosis is not the sole form of regulated cell death. Caspase-independent, but genetically regulated, forms of cell death include pyroptosis, necroptosis, parthanatos, and the recently discovered ferroptosis and autosis. Importantly, regulated necrosis can be modulated by small molecule inhibitors/activators, confirming the cell autonomous mechanism of these forms of cell death. The success of small molecule-mediated manipulation of regulated necrosis has produced great changes in the field of cell death research, and has also brought about significant changes in the fields of pharmacology as well as toxicology. In this review, we intend to summarize the modes of regulated cell death other than apoptosis, and discuss their implications in toxicology.

Topics: Animals; Apoptosis; Apoptosis Inducing Factor; Autophagy; Cell Death; Humans; Necrosis; Piperidines; Poly(ADP-ribose) Polymerases; Quinolines; Risk Assessment; Signal Transduction; Toxicology

Vacquinol‑1 (Vacq), a quinolone derivative, has recently been reported to display potent antitumor effects in glioblastomas by inducing cellular massive vacuolization and cell death. However, whether Vacq induces cytotoxicities in other types of cancers, and the potential underlying mechanism, remain to be investigated. In the present study, it was revealed that Vacq suppressed cell growth and colony formation in the hepatocellular carcinoma (HCC) cell lines BEL7402 and Huh7. In addition, treatment with Vacq increased the number of early and late apoptotic cells as assessed by flow cytometry with fluorescein isothiocyanate‑conjugated Annexin V and propidium iodide double staining. Notably, the effect by Vacq in the tested cells could be inhibited by pretreatment with a broad specificity caspase inhibitor Z‑VAD‑FMK, suggesting that Vacq may induce apoptosis in HCC cells. Morphologically, exposure to Vacq resulted in nuclear fragmentation and the apoptotic body formation in HCC cells. Furthermore, Vacq treatment increased the cleavage of caspase‑3, caspase‑9 and poly(adenosine diphosphate‑ribose) polymerase‑1. Mechanistic analysis revealed that Vacq upregulated the expressions of pro‑apoptotic proteins [B‑cell lymphoma 2 (bcl‑2)‑associated X protein (Bax) and Bcl‑2‑like protein 11] and downregulated the pro‑survival protein, Bcl‑2, expression in HCC cells. Furthermore, Vacq induced Bax translocation. Of note, Vacq displayed inhibitory effects on patient‑derived HCC cells in two‑dimensional (2D) and three-dimensional (3D) cultures. Taken together, the data suggested that Vacq induced intrinsic apoptosis and may be utilized as an effective reagent for HCC treatment.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Humans; Liver Neoplasms; Piperidines; Quinolines

Glioblastomas (GBM) are the most malignant brain tumors in humans and have a very poor prognosis. New therapeutic options are urgently needed. A novel drug, Vacquinol-1 (Vac), a quinolone derivative, displays promising properties by inducing rapid cell death in GBM but not in non-transformed tissues. Features of this type of cell death are compatible with a process termed methuosis. Here we tested Vac on a highly malignant glioma cell line observed by long-term video microscopy. Human dental-pulp stem cells (DPSCs) served as controls. A major finding was that an exogenous ATP concentration of as little as 1 μM counter regulated the Vac-induced cell death. Studies using carvacrol, an inhibitor of transient receptor potential cation channel, subfamily M, member 7 (TRPM7), demonstrated that the ATP-inducible inhibitory effect is likely to be via TRPM7. Exogenous ATP is of relevance in GBM with large necrotic areas. Our results support the use of GBM cultures with different grades of malignancy to address their sensitivity to methuosis. The video-microscopy approach presented here allows decoding of signaling pathways as well as mechanisms of chemotherapeutic resistance by long-term observation. Before implementing Vac as a novel therapeutic drug in GBM, cells from each individual patient need to be assessed for their ATP sensitivity. In summary, the current investigation supports the concept of methuosis, described as non-apoptotic cell death and a promising approach for GBM treatment. Tissue-resident ATP/necrosis may interfere with this cell-death pathway but can be overcome by a natural compound, carvacrol that even penetrates the blood-brain barrier.

Topics: Adenosine Triphosphate; Brain Neoplasms; Caspase 3; Caspase 7; Cell Death; Cell Line, Tumor; Cymenes; Gene Expression Regulation, Neoplastic; Glioblastoma; Humans; Monoterpenes; Piperidines; Protein Serine-Threonine Kinases; Quinolines; TRPM Cation Channels

Glioblastoma remains an incurable brain cancer. Drugs developed in the past 20 years have not improved the prognosis for patients, necessitating the development of new treatments. We have previously reported the therapeutic potential of the quinoline methanol Vacquinol-1 (1) that targets glioblastoma cells and induces cell death by catastrophic vacuolization. Compound 1 is a mixture of four stereoisomers due to the two adjacent stereogenic centers in the molecule, complicating further development in the preclinical setting. This work describes the isolation and characterization of the individual isomers of 1 and shows that these display stereospecific pharmacokinetic and pharmacodynamic features. In addition, we present a stereoselective synthesis of the active isomers, providing a basis for further development of this compound series into a novel experimental therapeutic for glioblastoma.

Topics: Animals; Antineoplastic Agents; Brain Neoplasms; Cell Death; Cell Line, Tumor; Glioblastoma; Humans; Mice; Models, Molecular; Piperidines; Quinolines; Stereoisomerism; Zebrafish

There is a growing need for new antibiotics. Compounds that target the proton motive force (PMF), uncouplers, represent one possible class of compounds that might be developed because they are already used to treat parasitic infections, and there is interest in their use for the treatment of other diseases, such as diabetes. Here, we tested a series of compounds, most with known antiinfective activity, for uncoupler activity. Many cationic amphiphiles tested positive, and some targeted isoprenoid biosynthesis or affected lipid bilayer structure. As an example, we found that clomiphene, a recently discovered undecaprenyl diphosphate synthase inhibitor active against Staphylococcus aureus, is an uncoupler. Using in silico screening, we then found that the anti-glioblastoma multiforme drug lead vacquinol is an inhibitor of Mycobacterium tuberculosis tuberculosinyl adenosine synthase, as well as being an uncoupler. Because vacquinol is also an inhibitor of M. tuberculosis cell growth, we used similarity searches based on the vacquinol structure, finding analogs with potent (∼0.5-2 μg/mL) activity against M. tuberculosis and S. aureus. Our results give a logical explanation of the observation that most new tuberculosis drug leads discovered by phenotypic screens and genome sequencing are highly lipophilic (logP ∼5.7) bases with membrane targets because such species are expected to partition into hydrophobic membranes, inhibiting membrane proteins, in addition to collapsing the PMF. This multiple targeting is expected to be of importance in overcoming the development of drug resistance because targeting membrane physical properties is expected to be less susceptible to the development of resistance.

Topics: Alkyl and Aryl Transferases; Anti-Infective Agents; Biophysical Phenomena; Clomiphene; Drug Discovery; Enzyme Inhibitors; Humans; Models, Molecular; Molecular Dynamics Simulation; Molecular Structure; Mycobacterium tuberculosis; Piperidines; Proton-Motive Force; Quinolines; Staphylococcus aureus; Uncoupling Agents

Glioblastoma multiforme (GBM) is the most aggressive form of brain cancer with marginal life expectancy. Based on the assumption that GBM cells gain functions not necessarily involved in the cancerous process, patient-derived glioblastoma cells (GCs) were screened to identify cellular processes amenable for development of targeted treatments. The quinine-derivative NSC13316 reliably and selectively compromised viability. Synthetic chemical expansion reveals delicate structure-activity relationship and analogs with increased potency, termed Vacquinols. Vacquinols stimulate death by membrane ruffling, cell rounding, massive macropinocytic vacuole accumulation, ATP depletion, and cytoplasmic membrane rupture of GCs. The MAP kinase MKK4, identified by a shRNA screen, represents a critical signaling node. Vacquinol-1 displays excellent in vivo pharmacokinetics and brain exposure, attenuates disease progression, and prolongs survival in a GBM animal model. These results identify a vulnerability to massive vacuolization that can be targeted by small molecules and point to the possible exploitation of this process in the design of anticancer therapies.

Topics: Animals; Brain Neoplasms; Cell Death; Glioblastoma; Heterografts; Humans; Hydroxyquinolines; MAP Kinase Kinase 4; Mice; Neoplasm Transplantation; Pinocytosis; Piperidines; Quinolines; Small Molecule Libraries; Vacuoles; Zebrafish

Attempts to treat cancer with drugs that target mutated proteins have met with mixed success. By screening for compounds that alter the phenotype of glioblastoma cells-an aggressive brain tumor-Kitambi et al. identify a potential new treatment of the disease and shed light on an unusual cell death mechanism.

Topics: Animals; Brain Neoplasms; Glioblastoma; Humans; Piperidines; Quinolines; Small Molecule Libraries