Unraveling the Mechanism of Platelet Aggregation Suppression by Thioterpenoids: Molecular Docking and In Vivo Antiaggregant Activity.

Natural monoterpenes and their derivatives are widely considered the effective ingredients for the design and production of novel biologically active compounds. In this study, by using the molecular docking technique, we examined the effects of two series of "sulfide-sulfoxide-sulfone" thioterpenoids containing different (e.g., bornane and pinane) monoterpene skeletons on the platelet's aggregation. Our data revealed that all the synthesized compounds exhibit inhibitory activities on platelet aggregation. For example, compound 1 effectively inhibited platelet activation and demonstrated direct binding with CD61 integrin, a well-known platelet GPIIb-IIIa receptor on platelets. We further examined the antiaggregant activity of the most active compound, 1, in vivo and compared its activity with that of acetylsalicylic acid and an oral GPIIb-IIIa blocker, orbofiban. We found that compound 1 demonstrates antiaggregant activity in rats when administered per os and its activity was comparable with that of acetylsalicylic acid and orbofiban. Moreover, similarly, tirofiban, a well-known GPIIb-IIIa blocker, compound 1, effectively decreased the expression of P-selectin to the values similar to those of the intact platelets. Collectively, here, we show, for the first time, the potent antiaggregant activity of compound 1 both in vitro and in vivo due to its ability to bind with the GPIIb-IIIa receptor on platelets.

Establishment and Characterization of Multi-Drug Resistant p53-Negative Osteosarcoma SaOS-2 Subline.

AIM: To establish a p53-negative osteosarcoma (OS) SaOS-2 cellular subline exhibiting resistance to specific chemotherapeutic agents, including topoisomerase II inhibitors, taxanes, and vinca alkaloids. METHODS: The OS subline exhibiting resistance to the chemotherapeutic agents indicated above was generated by the stepwise treatment of the parental SaOS-2 cell line with increasing concentrations of doxorubicin (Dox) for 5 months. Half-inhibitory concentrations (IC50) for Dox, vinblastine (Vin), and paclitaxel (PTX) were calculated by a colorimetric MTS-based assay. Crystal violet staining was used to assess cellular viability, whereas the proliferation capacities of cancer cells were monitored in real-time by the i-Celligence system. Expression of apoptotic markers (e.g., cleaved PARP and caspase-3), DNA repair proteins (e.g., ATM, DNA-PK, Nbs1, Rad51, MSH2, etc.), and certain ABC transporters (P-glycoprotein, MRP1, ABCG2, etc.) was assessed by western blotting and real-time PCR. Flow cytometry was used to examine the fluorescence intensity of Dox and ABC-transporter substrates (e.g., Calcein AM and CMFDA) and to assess their excretion to define the activity of specific ABC-transporters. To confirm OS resistance to Dox in vivo, xenograft experiments were performed. RESULTS: An OS subline generated by a stepwise treatment of the parental SaOS-2 cell line with increasing concentrations of Dox resulted in an increase in the IC50 for Dox, Vin, and PTX (~6-, 4-, and 30-fold, respectively). The acquisition of chemoresistance in vitro was also evidenced by the lack of apoptotic markers (e.g., cleaved PARP and caspase-3) in resistant OS cells treated with the chemotherapeutic agents indicated above. The development of the multidrug resistance (MDR) phenotype in this OS subline was due to the overexpression of ABCB1 (i.e., P-glycoprotein) and ABCC1 (i.e., multidrug resistance protein-1, MRP-1), which was evidenced on both mRNA and protein levels. Due to increased expression of MDR-related proteins, resistant OS exhibited an excessive efflux of Dox. Moreover, decreased accumulation of calcein AM, a well-known fluorescent substrate for both ABCB1 and ABCC1, was observed for resistant OS cells compared to their parental SaOS-2 cell line. Importantly, tariquidar and cyclosporin, well-known ABC inhibitors, retained the intensity of Dox-induced fluorescence in resistant SAOS-2 cells. Furthermore, in addition to the increased efflux of the chemotherapeutic agents from Dox-resistant OS cells, we found higher expression of several DNA repair proteins (e.g., Rad51 recombinase, Mre11, and Nbs1, activated forms of ATM, DNA-PK, Chk1, and Chk2, etc.), contributing to the chemoresistance due to the excessive DNA repair. Lastly, the in vivo study indicated that Dox has no impact on the SaOS-2 Dox-R xenograft tumor growth in a nude mouse model. CONCLUSIONS: An acquired resistance of OS to the chemotherapeutic agents might be due to the several mechanisms undergoing simultaneously on the single-cell level. This reveals the complexity of the mechanisms involved in the secondary resistance of OS to chemotherapies.

2-Amino-Pyrrole-Carboxylate Attenuates Homology-Mediated DNA Repair and Sensitizes Cancer Cells to Doxorubicin.

Despite a high efficacy of chemotherapy in cancer treatment, acquired resistance of tumors to certain chemotherapeutic agents and frequent side effects remain the major factors of unfavorable prognosis in most cancer patients with unresectable, metastatic and recurrent forms of the disease. The discovery of novel molecular targets in tumors and development of new therapeutic approaches to enhance the efficiency of chemotherapeutic agents remain the biggest challenges in current oncology. Here we examined the ability of pyrrole-based heterocyclic compound 2-APC to sensitize tumor cells to the topoisomerase II inhibitor doxorubicin. The study was performed on human cancer cell lines treated with 2-APC, paclitaxel, and doxorubicin. Expression of DNA repair was investigated by Western blotting, whereas protein-protein interactions were examined by co-immunoprecipitation. The synergism between the chemotherapeutic agents was assessed with the Synergy Finder program. Doxorubicin exhibited moderate cytotoxic effect against cancer cell lines (in particular, osteosarcoma cell lines). 2-APC in non-toxic concentrations substantially potentiated the cytotoxic effect of doxorubicin and induced apoptosis of cancer cells. This activity of 2-APC was due to its ability to impair DNA damage repair by decreasing the content of Rad51 recombinase via promoting its proteasomal degradation. Similar effects were observed for paclitaxel, which affects tubulin polymerization. Therefore, chemotherapeutic agents and chemical compounds interfering with the microtubule dynamics can potentiate the cytotoxic effects of DNA-damaging chemotherapeutic agents via impairment of DNA damage repair mechanisms in cancer cells.

Infigratinib (BGJ 398), a Pan-FGFR Inhibitor, Targets P-Glycoprotein and Increases Chemotherapeutic-Induced Mortality of Multidrug-Resistant Tumor Cells.

The microtubule-targeting agents (MTAs) are well-known chemotherapeutic agents commonly used for therapy of a broad spectrum of human malignancies, exhibiting epithelial origin, including breast, lung, and prostate cancer. Despite the impressive response rates shortly after initiation of MTA-based therapy, the vast majority of human malignancies develop resistance to MTAs due to the different mechanisms. Here, we report that infigratinib (BGJ 398), a potent FGFR1-4 inhibitor, restores sensitivity of a broad spectrum of ABCB1-overexpressing cancer cells to certain chemotherapeutic agents, including paclitaxel (PTX) and doxorubicin (Dox). This was evidenced for the triple-negative breast cancer (TNBC), and gastrointestinal stromal tumor (GIST) cell lines, as well. Indeed, when MDR-overexpressing cancer cells were treated with a combination of BGJ 398 and PTX (or Dox), we observed a significant increase of apoptosis which was evidenced by an increased expression of cleaved forms of PARP, caspase-3, and increased numbers of Annexin V-positive cells, as well. Moreover, BGJ 398 used in combination with PTX significantly decreased the viability and proliferation of the resistant cancer cells. As expected, no apoptosis was found in ABCB1-overexpressing cancer cells treated with PTX, Dox, or BGJ 398 alone. Inhibition of FGFR-signaling by BGJ 398 was evidenced by the decreased expression of phosphorylated (i.e., activated) forms of FGFR and FRS-2, a well-known adaptor protein of FGFR signaling, and downstream signaling molecules (e.g., STAT-1, -3, and S6). In contrast, expression of MDR-related ABC-transporters did not change after BGJ 398 treatment, thereby suggesting an impaired function of MDR-related ABC-transporters. By using the fluorescent-labeled chemotherapeutic agent PTX-Alexa488 (Flutax-2) and doxorubicin, exhibiting an intrinsic fluorescence, we found that BGJ 398 substantially impairs their efflux from MDR-overexpressing TNBC cells. Moreover, the efflux of Calcein AM, a well-known substrate for ABCB1, was also significantly impaired in BGJ 398-treated cancer cells, thereby suggesting the ABCB1 as a novel molecular target for BGJ 398. Of note, PD 173074, a potent FGFR1 and VEGFR2 inhibitor failed to retain chemotherapeutic agents inside ABCB1-overexpressing cells. This was consistent with the inability of PD 173074 to sensitize Tx-R cancer cells to PTX and Dox. Collectively, we show here for the first time that BGJ 398 reverses the sensitivity of MDR-overexpressing cancer cells to certain chemotherapeutic agents due to inhibition of their efflux from cancer cells via ABCB1-mediated mechanism.

Central Mini-plication of the Medial Rectus for Convergence Insufficiency.

Five cases with a mean (± SD) age of 61 (12.02) years are described to study the outcomes of treatment with central mini-plication of the medial rectus (MR) muscles in adult convergence insufficiency with diplopia and near exotropia: mean preoperative deviation: 18 (± 2) pd. Surgical outcome was considered to be favorable when diplopia and symptoms were resolved and final exotropia at near was ≤8 pd at the end of follow-up. A central mini-plication of the medial rectus (MR) muscles was performed in 5 patients (4 unilateral). Overcorrection at distance vision was recorded in 3 cases; this resolved by 3 months postoperatively. There was not overcorrection at near vision in any case. None of the cases operated on had overcorrection at the end of follow-up. The final horizontal deviation was ≤8 pd at near vision, except for 1 case. Symptoms and diplopia resolved in every case but 2/5 required reoperations. The mean follow-up was 8 (2.12) months. Central mini-plication of 1 or 2 medial rectus muscles can improve the symptoms and signs of exotropia associated with convergence insufficiency when exercises and the prisms are rejected by the patients and when these approaches have not solved the problem.

Inhibition of fibroblast growth factor receptor-signaling sensitizes imatinib-resistant gastrointestinal stromal tumors to low doses of topoisomerase II inhibitors.

The acquired resistance of gastrointestinal stromal tumors (GISTs) to the targeted-based therapy remains the driving force to identify the novel approaches that are capable of increasing the sensitivity of GISTs to the current therapeutic regimens. Our present data show that BGJ398, a selective fibroblast growth factor receptor (FGFR) inhibitor, sensitizes imatinib (IM)-resistant GIST cells with receptor tyrosine kinase (RTK) switch (loss of c-KIT/gain of pFGFR2a) to the low doses of topoisomerase II inhibitors - doxorubicin (Dox) and etoposide (Eto). Mechanistically, pretreatment of IM-resistant GIST cells with BGJ398 for 12 h markedly enhanced proapoptotic and growth-suppressive effects of Dox (or Eto). Indeed, a significant cleavage of PARP and caspase-3 was observed in GIST cells treated with a combination of FGFR and topoisomerase II inhibitor. In contrast, no signs of apoptosis were detected in IM-resistant GIST cells treated with BGJ398, whereas the low doses of Dox (Eto) exerted the minor proapoptotic effects on GISTs. The mechanism of BGJ398-induced sensitization of GIST to topoisomerase II inhibitors might be because of attenuation of DNA damage signaling and repair. Indeed, we observed a marked decrease in Rad51 expression in GIST cells treated with BGJ398 together with Dox. Similar results were obtained when an overexpressed pFGFR2a was knocked down by corresponding siRNA before Dox (Eto) exposure. Moreover, FGFR inhibition/depletion caused a loss of Rad51 foci in Dox-treated GIST cells, suggesting that FGFR-signaling plays an important regulatory role in homology-mediated DNA repair. Our data show that combined therapy (RTKs inhibitors supplemented with low doses of topoisomerase II inhibitors) might be effective for unresectable and metastatic forms of GISTs. In case of resistance to IM because of RTKs switch indicated above, FGFR inhibitors (e.g. BGJ398) might be potentially useful because of their ability to sensitize tumor cells to topoisomerase II inhibitors and induce tumor cell apoptosis by targeting DNA double-strand breaks repair.

The off-label use of drugs for parenteral nutrition as a solvent of substances slightly soluble in water in pharmacological research.

Because of the problem to evaluate biological activity in water-soluble substances in all phases of preclinical and clinical studies, the research work enabled to develop the original solvent for poorly soluble compounds based on substances for parenteral nutrition. The main aim is to examine the impact of the original solvent based on substances for parenteral nutrition on biological systems exemplified by the hemostatic system, characterized by sensitivity and variability of the effects in response to any impact, and its comparison with the solvents that are conventional in pharmacological research. Experimental work is performed according to the "guidance on preclinical research of new pharmacological substances" in vitro. The findings show that traditional solvents at low dosages affect all the researched indicators of the hemostasis system. The smallest effect in respect of the hemostatic system was characterized by ethanol, and the most apparent antiaggregational effect was registered with dioxane. 10% concentration of original blend of lipids made no effect on hemostasis system. Thus, according to their own findings and experience in application of lipid emulsions as substances of parenteral nutrition, they can be considered to be an adequate solvent in all phases of preclinical and clinical studies of new drugs.

Cytokine Profile of Patients with Allergic Rhinitis Caused by Pollen, Mite, and Microbial Allergen Sensitization.

Allergic rhinitis (AR) is especially prevalent among the population of large cities. Immunologically, the airway epithelium is a region where the population of allergen-presenting cells concentrates. These cells actively express a group of receptors of the innate immune system. A specific cytokine profile is its representation. The study was aimed at evaluating the cytokine profile in patients with seasonal and perennial allergic rhinitis. The cytokine profile of nasal secretion and blood serum of 44 patients with AR was studied. 24 of them had seasonal allergic rhinitis (SAR), and 20 patients suffered from perennial allergic rhinitis (PAR). The patients' age ranged from 4 to 60 years. It was determined in our study that the activation of the GM-CSF production retained in patients with PAR sensitized to mite allergen components (Dermatophagoides pteronyssinus). There was a higher production profile of TNF-α and TSLP in nasal secretion in the patients with perennial allergic rhinitis and additional high sensitization to SEs. Sensitization to mold fungal allergen components significantly increases in patients with seasonal allergic rhinitis. They demonstrated high level of sensitization to the Aspergillus fumigatus component m3. Thus, along with other clinical trials, the study performed would clarify some aspects of molecular pathogenesis of human allergic rhinitis.

Fibrosis biomarkers in workers exposed to MWCNTs.

Multi-walled carbon nanotubes (MWCNT) with their unique physico-chemical properties offer numerous technological advantages and are projected to drive the next generation of manufacturing growth. As MWCNT have already found utility in different industries including construction, engineering, energy production, space exploration and biomedicine, large quantities of MWCNT may reach the environment and inadvertently lead to human exposure. This necessitates the urgent assessment of their potential health effects in humans. The current study was carried out at NanotechCenter Ltd. Enterprise (Tambov, Russia) where large-scale manufacturing of MWCNT along with relatively high occupational exposure levels was reported. The goal of this small cross-sectional study was to evaluate potential biomarkers during occupational exposure to MWCNT. All air samples were collected at the workplaces from both specific areas and personal breathing zones using filter-based devices to quantitate elemental carbon and perform particle analysis by TEM. Biological fluids of nasal lavage, induced sputum and blood serum were obtained from MWCNT-exposed and non-exposed workers for assessment of inflammatory and fibrotic markers. It was found that exposure to MWCNTs caused significant increase in IL-1ß, IL6, TNF-α, inflammatory cytokines and KL-6, a serological biomarker for interstitial lung disease in collected sputum samples. Moreover, the level of TGF-ß1 was increased in serum obtained from young exposed workers. Overall, the results from this study revealed accumulation of inflammatory and fibrotic biomarkers in biofluids of workers manufacturing MWCNTs. Therefore, the biomarkers analyzed should be considered for the assessment of health effects of occupational exposure to MWCNT in cross-sectional epidemiological studies.

Circulating Microparticles Alter Formation, Structure, and Properties of Fibrin Clots.

Despite the importance of circulating microparticles in haemostasis and thrombosis, there is limited evidence for potential causative effects of naturally produced cell-derived microparticles on fibrin clot formation and its properties. We studied the significance of blood microparticles for fibrin formation, structure, and susceptibility to fibrinolysis by removing them from platelet-free plasma using filtration. Clots made in platelet-free and microparticle-depleted plasma samples from the same healthy donors were analyzed in parallel. Microparticles accelerate fibrin polymerisation and support formation of more compact clots that resist internal and external fibrinolysis. These variations correlate with faster thrombin generation, suggesting thrombin-mediated kinetic effects of microparticles on fibrin formation, structure, and properties. In addition, clots formed in the presence of microparticles, unlike clots from the microparticle-depleted plasma, contain 0.1-0.5-µm size granular and CD61-positive material on fibres, suggesting that platelet-derived microparticles attach to fibrin. Therefore, the blood of healthy individuals contains functional microparticles at the levels that have a procoagulant potential. They affect the structure and stability of fibrin clots indirectly through acceleration of thrombin generation and through direct physical incorporation into the fibrin network. Both mechanisms underlie a potential role of microparticles in haemostasis and thrombosis as modulators of fibrin formation, structure, and resistance to fibrinolysis.