Synthesis and in vitro cytotoxicity of benzoxazole-based PPARα/γ antagonists in colorectal cancer cell lines.

A series of benzoxazole-based amides and sulfonamides were synthesized and evaluated for their human peroxisome proliferator-activated receptor (PPAR)α and PPARγ activity. All tested compounds showed a dual antagonist profile on both PPAR subtypes; based on transactivation results, seven compounds were selected to test their in vitro antiproliferative activity in a panel of eight cancer cell lines with different expression rates of PPARα and PPARγ. 3f was identified as the most cytotoxic compound, with higher potency in the colorectal cancer cell lines HT-29 and HCT116. Compound 3f induced a concentration-dependent activation of caspases and cell-cycle arrest in both colorectal cancer models. Docking experiments were also performed to shed light on the putative binding mode of this novel class of dual PPARα/γ antagonists.

Sphingolipid Metabolism in Tumor Cells.

Sphingolipids are a diverse family of complex lipids typically composed of a sphingoid base bound to a fatty acid via amide bond. The metabolism of sphingolipids has long remained out of focus of biochemical studies. Recently, it has been attracting an increasing interest of researchers because of different and often multidirectional effects demonstrated by sphingolipids with a similar chemical structure. Sphingosine, ceramides (N-acylsphingosines), and their phosphorylated derivatives (sphingosine-1-phosphate and ceramide-1-phosphates) act as signaling molecules. Ceramides induce apoptosis and regulate stability of cell membranes and cell response to stress. Ceramides and sphingoid bases slow down anabolic and accelerate catabolic reactions, thus suppressing cell proliferation. On the contrary, their phosphorylated derivatives (ceramide-1-phosphate and sphingosine-1-phosphate) stimulate cell proliferation. Involvement of sphingolipids in the regulation of apoptosis and cell proliferation makes them critically important in tumor progression. Sphingolipid metabolism enzymes and sphingolipid receptors can be potential targets for antitumor therapy. This review describes the main pathways of sphingolipid metabolism in human cells, with special emphasis on the properties of this metabolism in tumor cells.

Targeting Methionine Addiction of Cancer Cells with Methioninase.

All types of cancer cells are addicted to methionine, which is known as the Hoffman effect. Restricting methionine inhibits the growth and proliferation of all tested types of cancer cells, leaving normal cells unaffected. Targeting methionine addiction with methioninase (METase), either alone or in combination with common cancer chemotherapy drugs, has been shown as an effective and safe therapy in various types of cancer cells and animal cancer models. About six years ago, recombinant METase (rMETase) was found to be able to be taken orally as a supplement, resulting in anecdotal positive results in patients with advanced cancer. Currently, there are 8 published clinical studies on METase, including two from the 1990s and six more recent ones. This review focuses on the results of clinical studies on METase-mediated methionine restriction, in particular, on the dosage of oral rMETase taken alone as a supplement or in combination with common chemotherapeutic agents in patients with advanced cancer.

Upconversion Nanoparticles Intercalated in Large Polymer Micelles for Tumor Imaging and Chemo/Photothermal Therapy.

Frontiers in theranostics are driving the demand for multifunctional nanoagents. Upconversion nanoparticle (UCNP)-based systems activated by near-infrared (NIR) light deeply penetrating biotissue are a powerful tool for the simultaneous diagnosis and therapy of cancer. The intercalation into large polymer micelles of poly(maleic anhydride-alt-1-octadecene) provided the creation of biocompatible UCNPs. The intrinsic properties of UCNPs (core@shell structure NaYF4:Yb3+/Tm3+@NaYF4) embedded in micelles delivered NIR-to-NIR visualization, photothermal therapy, and high drug capacity. Further surface modification of micelles with a thermosensitive polymer (poly-N-vinylcaprolactam) exhibiting a conformation transition provided gradual drug (doxorubicin) release. In addition, the decoration of UCNP micelles with Ag nanoparticles (Ag NPs) synthesized in situ by silver ion reduction enhanced the cytotoxicity of micelles at cell growth temperature. Cell viability assessment on Sk-Br-3, MDA-MB-231, and WI-26 cell lines confirmed this effect. The efficiency of the prepared UCNP complex was evaluated in vivo by Sk-Br-3 xenograft regression in mice for 25 days after peritumoral injection and photoactivation of the lesions with NIR light. The designed polymer micelles hold promise as a photoactivated theranostic agent with quattro-functionalities (NIR absorption, photothermal effect, Ag NP cytotoxicity, and Dox loading) that provides imaging along with chemo- and photothermal therapy enhanced with Ag NPs.

[3+2]-Cycloaddition of Nitrile Imines to Parabanic Acid Derivatives-An Approach to Novel Spiroimidazolidinediones.

Approximately 1,3-Dipolar cycloaddition of imidazolidine derivatives containing exocyclic double bonds is a convenient method of creating spiro-conjugated molecules with promising anticancer activity. In this work, the derivatives of parabanic acid (2-thioxoimidazolidine-4,5-diones and 5-aryliminoimidazolidine-2,4-diones) were first investigated as dipolarophiles in the reactions with nitrile imines. The generation of nitrile imines was carried out either by the addition of tertiary amine to hydrazonoyl chlorides «drop by drop¼ or using the recently proposed diffusion mixing technique, which led to ~5-15% increases in target compound yields. It was found that the addition of nitrile imines to C=S or C=N exocyclic double bonds led to 1,2,4-thiazolines or triazolines and occurred regioselectively in accordance with the ratio of FMO coefficients of reactants. The yield of the resulting spiro-compound depended on the presence of alkyl substituents in the nitrile imine structure and was significantly decreased in reactions with imines with strong electron donor or electron-withdrawing groups. Some of the obtained compounds showed reasonable in vitro cytotoxicity. IC50 values were calculated for HCT116 (colon cancer) cells using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test.

Antitumor Effect of Bleomycin Nanoaerosol in Murine Carcinoma Model.

Bleomycin, which is widely used as an antitumor agent, possesses serious adverse effects such as pulmonary toxicity. Local nanoaerosol deposition for lung cancer treatment is a promising alternative to drug delivery to lung lesions. The aim of this work is to test the hypothesis that bleomycin nanoaerosol can be effectively used to treat multiple lung metastases. To obtain bleomycin nanoaerosol, an aerosol generator based on electrospray of a solution of a nonvolatile substance with gas-phase neutralization of charged aerosol particles was used. Lung metastases in murine Lewis lung carcinoma and B16 melanoma animal models were counted. The effect of inhaled bleomycin nanoparticles on the number and volume of metastases, as well as pulmonary side effects, was investigated. Using a mouse exposure chamber, the dose-dependent effect of inhaled bleomycin on tumor volume was evaluated in comparison with intraperitoneal administration. Bleomycin nanoaerosol reduced the volume of metastases and produced a higher antitumor effect at much lower doses. It has been established that long-term exposure to nanoaerosol with a low dose of bleomycin is capable of suppressing cancer cell growth. The treatment was well tolerated. In the lungs, minor changes were found in the form of focal-diffuse infiltration of the lung parenchyma.

Oxidative Stress and Redox-Dependent Signaling in Prostate Cancer.

Tumor emergence and progression is complicated by the dual role of reactive oxygen species (ROS). Low concentrations of ROS are essential for many intracellular metabolic processes and cell proliferation, while excessive ROS generation disrupts the mechanisms of cancer suppression, leading to the cell damage and death. A long-term imbalance in the ROS/antioxidant ratio and upregulation of the ROS generation due to the reduced efficacy of the antioxidant defense system cause chronic oxidative stress resulting in the damage of proteins, lipid, and DNA molecules and cancer development. Numerous data demonstrate that prostate cancer (the most common cancer in males) is associated with the development of oxidative stress. However, the reasons for the emergence of prostate cancer, as well as changes in the redox signaling and cellular redox homeostasis in this disease, are still poorly understood. The review examines the role of prooxidant and antioxidant enzyme systems, the imbalance in their activity leading to the oxidative stress development, changes in the key components of redox signaling, and the role of microRNAs in the modulation of redox status of cancer cells in prostate cancer.

Antiproliferative, proapoptotic, and tumor-suppressing effects of the novel anticancer agent alsevirone in prostate cancer cells and xenografts.

The aim of this study was to explore the mechanisms of action of alsevirone in prostate cancer (PC) in vitro and in vivo: CYP17A1 inhibition, cytotoxic, apoptotic, and antitumor effects in comparison with abiraterone. The CYP17A1-inhibitory activity was investigated in rat testicular microsomes using high-performance liquid chromatography. Testosterone levels were evaluated using enzyme-linked immunoassay. IC50 values were calculated for PC3, DU-145, LNCaP, and 22Rv1 cells using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test. The antitumor effect in vivo was studied in DU-145 and 22Rv1 subcutaneous xenografts in Balb/c nude mice. Alsevirone reduced the CYP17A1-inhibitory activity by 98% ± 0.2%. A statistically significant reduction in the testosterone concentration in murine blood was recorded after the 7th administration of 300 mg/kg alsevirone at 0.31 ± 0.03 ng/ml (p < .001) versus 0.98 ± 0.22 ng/ml (p = .392) after abiraterone administration and 1.52 ± 0.49 ng/ml in control animals. Alsevirone was more cytotoxic than abiraterone in DU-145, LNCaP, and 22Rv1 cells, with IC50 values of 23.80 ± 1.18 versus 151.43 ± 23.70 µM, 22.87 ± 0.54 versus 28.80 ± 1.61 µM, and 35.86 ± 5.63 versus 109.87 ± 35.15 µM, respectively. Alsevirone and abiraterone significantly increased annexin V-positive, caspase 3/7-positive, and activated Bcl-2-positive cells. In 22Rv1 xenografts, alsevirone 300 mg/kg × 10/24 h per os inhibited tumor growth: on Day 9 of treatment, tumor growth inhibition = 59% (p = .022). Thus, alsevirone demonstrated significant antitumor activity associated with CYP17A1 inhibition, apoptosis in PC cells, and testosterone reduction.

Methionine γ-Lyase-Daidzein in Combination with S-Propyl-L-cysteine Sulfoxide as a Targeted Prodrug Enzyme System for Malignant Solid Tumor Xenografts.

The purpose of this study was to determine the anticancer effect of dipropyl thiosulfinate produced in situ by the pharmacological pair: (1) conjugated with daidzein C115H methionine γ-lyase (EC 4.4.1.11, C115H MGL-Dz) and (2) the substrate, S-propyl-L-cysteine sulfoxide (propiin) against various solid tumor types in vitro and in vivo. The MTT test was used to calculate IC50 values for HT29, COLO205 and HCT116 (colon cancer); Panc1 and MIA-PaCa2 (pancreatic cancer); and 22Rv1, DU-145 and PC3 (prostate cancer). The most promising effect for colon cancer cells in vitro was observed in HT29 (IC50 = 6.9 µM). The IC50 values for MIA-PaCa2 and Panc1 were 3.4 and 3.8 µM, respectively. Among prostate cancer cells, 22Rv1 was the most sensitive (IC50 = 5.4 µM). In vivo antitumor activity of the pharmacological pair was studied in HT29, SW620, Panc1, MIA-PaCa2 and 22Rv1 subcutaneous xenografts in BALB/c nude mice. The application of C115H MGL-Dz /propiin demonstrated a significant reduction in the tumor volume of Panc1 (TGI 67%; p = 0.004), MIA-PaCa2 (TGI 50%; p = 0.011), HT29 (TGI 51%; p = 0.04) and 22Rv1 (TGI 70%; p = 0.043) xenografts. The results suggest that the combination of C115H MGL-Dz/propiin is able to suppress tumor growth in vitro and in vivo and the use of this pharmacological pair can be considered as a new strategy for the treatment of solid tumors.

Synthesis and Preclinical Evaluation of Small-Molecule Prostate-Specific Membrane Antigen-Targeted Abiraterone Conjugate.

Prostate cancer is the second most common type of cancer among men. The main method of its treatment is androgen deprivation therapy, which has a wide range of side effects. One of the solutions to this challenge is the targeted delivery of drugs to prostate cancer cells. In this study, we performed the synthesis of a novel small-molecule PSMA-targeted conjugate based on abiraterone. Cytotoxicity, the induction of intracellular reactive oxygen species, and P450-cytochrome species inhibition were investigated for this conjugate PSMA-abiraterone. The conjugate demonstrated a preferential effect on prostate tumor cells, remaining inactive at up to 100 µM in human fibroblast cells. In addition, it revealed preferential efficacy, specifically on PSMA-expressing lines with a 65% tumor growth inhibition level on 22Rv1 (PSMA+) xenografts after 14-fold oral administration of PSMA-Abi at a single dose of 500 mg/kg (7.0 g/kg total dose) was observed. This compound showed significantly reduced acute toxicity with comparable efficacy compared to AbiAc.

Pharmacophore hybridization approach to discover novel pyrazoline-based hydantoin analogs with anti-tumor efficacy.

In search for new and safer anti-cancer agents, a structurally guided pharmacophore hybridization strategy of two privileged scaffolds, namely diaryl pyrazolines and imidazolidine-2,4-dione (hydantoin), was adopted resulting in a newfangled series of compounds (H1-H22). Herein, a bio-isosteric replacement of "pyrrolidine-2,5-dione" moiety of our recently reported antitumor hybrid incorporating diaryl pyrazoline and pyrrolidine-2,5-dione scaffolds with "imidazoline-2,4-dione" moiety has been incorporated. Complete biological studies revealed the most potent analog among all i.e. compound H13, which was at-least 10-fold more potent compared to the corresponding pyrrolidine-2,5-dione, in colon and breast cancer cells. In-vitro studies showed activation of caspases, arrest of G0/G1 phase of cell cycle, decrease in the expression of anti-apoptotic protein (Bcl-2) and increased DNA damage. In-vivo assay on HT-29 (human colorectal adenocarcinoma) animal xenograft model unveiled the significant anti-tumor efficacy along with oral bioavailability with maximum TGI 36% (i.p.) and 44% (per os) at 50 mg/kg dose. These findings confirm the suitability of hybridized pyrazoline and imidazolidine-2,4-dione analog H13 for its anti-cancer potential and starting-point for the development of more efficacious analogs.

Inhibition of telomerase activity by splice-switching oligonucleotides targeting the mRNA of the telomerase catalytic subunit affects proliferation of human CD4+ T lymphocytes.

Telomerase activity is regulated at the mRNA level by alternative splicing (AS) of its catalytic subunit hTERT. The aim of this study was to define the ability of splice-switching oligonucleotides (SSOs) that pair with hTERT pre-mRNA to induce AS and inhibit telomerase activity in human CD4+ T lymphocytes. SSOs that blocked the binding of a single splicing regulatory protein, SRp20 or SRp40, to its site within intron 8 of hTERT pre-mRNA demonstrated rather moderate capacities to induce AS and inhibit telomerase. However, a SSO that blocked the interaction of both SRp20 and SRp40 proteins with pre-mRNA was the most active. Cultivation of lymphocytes with spliced hTERT and inhibited telomerase resulted in the reduction of proliferative activity without significant induction of cell death. These results should facilitate further investigation of telomerase activity regulation, and antitelomerase SSOs could become promising agents for antiproliferative cell therapy.

Murine regulatory T cells induce death of effector T, B, and NK lymphocytes through a contact-independent mechanism involving telomerase suppression and telomere-associated senescence.

Regulatory T cells (Tregs) suppress the activity of effector T, B and NK lymphocytes and sustain immunological tolerance, but the proliferative activity of suppressed cells remains unexplored. In the present study, we report that mouse Tregs can induce replicative senescence and the death of responder mouse CD4+CD25- T cells, CD8+ T cells, B cells and NK cells in vitro and in vivo. Contact-independent in vitro co-cultivation with Tregs up-regulated endonuclease G (EndoG) expression and its translocation to the nucleus in responder cells. EndoG localization in the nucleus induced alternative mRNA splicing of the telomerase catalytic subunit Tert and telomerase inhibition. The lack of telomerase activity in proliferating cells led to telomere loss followed by the development of senescence and cell death. Injection of Tregs into mice resulted in EndoG-associated alternative splicing of Tert, telomerase inhibition, telomere loss, senescence development and increased cell death in vivo. The present study describes a novel contact-independent mechanism by which Tregs specify effector cell fate and provides new insights into cellular crosstalk related to immune suppression.

Rhodospirillum rubruml-asparaginase targets tumor growth by a dual mechanism involving telomerase inhibition.

Rhodospirillum rubruml-asparaginase mutant RrA E149R, V150P, F151T (RrA) was previously identified to down-regulate telomerase activity along with catalyzing the hydrolysis of l-asparagine. The aim of this study was to define the effect of prolonged RrA exposure on telomerase activity, maintenance of telomeres and proliferation of cancer cells in vitro and in vivo. RrA could inhibit telomerase activity in SCOV-3, SkBr-3 and A549 human cancer cell lines due to its ability to down-regulate the expression of telomerase catalytic subunit hTERT. Telomerase activity in treated cells did not exceeded 29.63 ± 12.3% of control cells. Continuous RrA exposure of these cells resulted in shortening of telomeres followed by cell death in vitro. Using real time PCR we showed that length of telomeres in SCOV-3 cells has been gradually decreasing from 10105 ± 2530 b.p. to 1233 ± 636 b.p. after 35 days of cultivation. RrA treatment of xenograft models in vivo showed slight inhibition of tumor growth accompanied with 49.5-53.3% of decrease in hTERT expression in the all tumors. However down-regulation of hTERT expression, inhibition of telomerase activity and the loss of telomeres was significant in response to RrA administration in xenograft models. These results should facilitate further investigations of RrA as a potent therapeutic protein.

Comparative immunogenicity and structural analysis of epitopes of different bacterial L-asparaginases.

BACKGROUND: E.coli type II L-asparaginase is widely used for treatment of acute lymphoblastic leukemia. However, serious side effects such as allergic or hypersensitivity reactions are common for L-asparaginase treatment. Methods for minimizing immune response on L-asparaginase treatment in human include bioengeneering of less immunogenic version of the enzyme or utilizing the homologous enzymes of different origin. To rationalize these approaches we compared immunogenicity of L-asparaginases from five bacterial organisms and performed sequence-structure analysis of the presumable epitope regions. METHODS: IgG and IgM immune response in C57B16 mice after immunization with Wollinella succinogenes type II (WsA), Yersinia pseudotuberculosis type II (YpA), Erwinia carotovora type II (EwA), and Rhodospirillum rubrum type I (RrA) and Escherichia coli type II (EcA) L-asparaginases was evaluated using standard ELISA method. The comparative bioinformatics analysis of structure and sequence of the bacterial L-asparaginases presumable epitope regions was performed. RESULTS: We showed different immunogenic properties of five studied L-asparaginases and confirmed the possibility of replacement of EcA with L-asparaginase from different origin as a second-line treatment. Studied L-asparaginases might be placed in the following order based on the immunogenicity level: YpA > RrA, WsA ≥ EwA > EcA. Most significant cross-immunogenicity was shown between EcA and YpA. We propose that a long N-terminus of YpA enzyme enriched with charged aminoacids and tryptophan could be a reason of higher immunogenicity of YpA in comparison with other considered enzymes. Although the recognized structural and sequence differences in putative epitope regions among five considered L-asparaginases does not fully explain experimental observation of the immunogenicity of the enzymes, the performed analysis set the foundation for further research in this direction. CONCLUSIONS: The performed studies showed different immunogenic properties of L-asparaginases and confirmed the possibility of replacement of EcA with L-asparaginase from different origin. The preferable enzymes for the second line treatment are WsA, RrA, or EwA.

The potential of methioninase for cancer treatment.

Cancer cells are addicted to L-methionine (L-Met) and have a much greater requirement for L-Met than normal cells due to excess transmethylation, termed the Hoffman effect. By targeting this vulnerability through dietary restriction of L-Met, researchers have been able to achieve promising results in inhibiting tumor growth and eradicating cancer cells. Methioninase (EC 4.4.1.11; METase) catalyzes the transformation of L-Met into α-ketobutyrate, ammonia, and methanethiol. The use of METase was initially limited due to its poor stability in vivo, high immunogenicity, and enzyme-induced inactivating antibodies. These issues could be partially resolved by PEGylation, encapsulation in erythrocytes, and various site-directed mutagenesis. The big breakthrough came when it was discovered that METase is effectively administered orally. The enzyme L-asparaginase is approved by the FDA for treatment of acute lymphoblastic leukemia. METase has more potential as a therapeutic since addiction to L-Met is a general and fundamental hallmark of cancer.

3,4-Diarylisoxazoles-Analogues of Combretastatin A-4: Design, Synthesis, and Biological Evaluation In Vitro and In Vivo.

Focusing on the molecular docking results, a series of 3,4-diarylisoxazoles, analogues of Combretastatin A4, bearing various substituents at the fifth position of the isoxazole ring and pharmacophore groups bioisosteric to methoxy substituent at ring B, were synthesized in good yields and high regioselectivity. Depending on the substituent at C5, three approaches were chosen for the construction of isoxazole ring, including nitrosation of gem-dihalocyclopropanes, nitrile oxide synthesis, and difluoromethoxylation of isoxazolone to afford 5-haloisoxazoles, 5-unsubstituted isoxazoles, and 5-difluoromethoxyisoxazoles, respectively. Isoxazoles 43 and 45 showed selective cytotoxicity and antitubulin inhibition properties in vitro, with pharmacodynamic profiles closely related to that of CA-4. Both of them slow down tumor growth (66-74%) in mouse xenografts and slightly exceed in effectiveness Combretastatin A4-phosphate itself.

Physiologically based pharmacokinetic model for predicting the biodistribution of albumin nanoparticles after induction and recovery from acute lung injury.

The application of nanomedicine in the treatment of acute lung injury (ALI) has great potential for the development of new therapeutic strategies. To gain insight into the kinetics of nanocarrier distribution upon time-dependent changes in tissue permeability after ALI induction in mice, we developed a physiologically based pharmacokinetic model for albumin nanoparticles (ANP). The model was calibrated using data from mice treated with intraperitoneal LPS (6 mg/kg), followed by intravenous ANP (0.5 mg/mouse or about 20.8 mg/kg) at 0.5, 6, and 24 h. The simulation results reproduced the experimental observations and indicated that the accumulation of ANP in the lungs increased, reaching a peak 6 h after LPS injury, whereas it decreased in the liver, kidney, and spleen. The model predicted that LPS caused an immediate (within the first 30 min) dramatic increase in lung and kidney tissue permeability, whereas splenic tissue permeability gradually increased over 24 h after LPS injection. This information can be used to design new therapies targeting specific organs affected by bacterial infections and potentially by other inflammatory insults.

Correction: Plyasova et al. Penetration into Cancer Cells via Clathrin-Dependent Mechanism Allows L-Asparaginase from Rhodospirillum rubrum to Inhibit Telomerase. Pharmaceuticals 2020, 13, 286.

In the original publication [...].

m6A Methylation in Regulation of Antiviral Innate Immunity.

The epitranscriptomic modification m6A is a prevalent RNA modification that plays a crucial role in the regulation of various aspects of RNA metabolism. It has been found to be involved in a wide range of physiological processes and disease states. Of particular interest is the role of m6A machinery and modifications in viral infections, serving as an evolutionary marker for distinguishing between self and non-self entities. In this review article, we present a comprehensive overview of the epitranscriptomic modification m6A and its implications for the interplay between viruses and their host, focusing on immune responses and viral replication. We outline future research directions that highlight the role of m6A in viral nucleic acid recognition, initiation of antiviral immune responses, and modulation of antiviral signaling pathways. Additionally, we discuss the potential of m6A as a prognostic biomarker and a target for therapeutic interventions in viral infections.