DZ-BAU2021-14N AS NOVEL PYRAZOLOPYRIDINE NANOCRYSTALS: APPRAISAL OF ANTICANCER ACTIVITY AGAINST HCT-116 AND HT-29 COLORECTAL CANCER CELL LINES

Mentioning DZ-BAU2021-14 (C19H17N5O2,347.370 g/mol) developed in BAU Labs, its promising preliminary antitumor effect nominated it to be selected as a lead antiproliferative compound against colorectal cancer cell lines owing to its proved Cyclin Dependent Kinase 2 (CDK2) inhibition (Kassem et al., 2021). Solving many problems restricting traditional cancer therapy, nanotechnology is offering safety margins and targeted delivery of poorly soluble drug. The potential effect of this compound was combined with the advantages of nanotechnology, precisely nanocrystals to achieve better antiproliferative and hopeful less cytotoxic patterns. The nanocrystals DZ-BAU2021-14N were prepared by an antisolvent precipitation technique using Poloxamer 407 and Cremophor® RH 40 as stabilizers. The nanocrystals were obtained with a nanometric particle size (89.80 ± 11.2 nm) and a negative zeta potential (-32.6 ± 0.50 mV) and were stable at 4 ± 0.5°C with no significant change in particle size or zeta potential. The anticancer activity of DZ-BAU2021-14 and DZ-BAU2021-14N were assessed. Their antiproliferative effects against colorectal cancer cell lines HCT-116 and HT-29 were studied via viability assay. In addition, their cytotoxic effects on non-tumorigenic cell lines NCM-460D were evaluated and respective IC50 values were determined. Different responses were obtained; DZ-BAU2021-14N provided lower IC50 on HCT-116 compared to the free drug DZ-BAU2021-14 (27 and 22 µM, respectively). The safety profile of the free drug was reflected by its IC50 on NCM-460D of 200µM while that of drug nanocrystals showed relative cytotoxicity with IC50 of 33µM, and this requires further investigation to study this response

Association of snR190 snoRNA chaperone with early pre-60S particles is regulated by the RNA helicase Dbp7 in yeast

Synthesis of eukaryotic ribosomes involves the assembly and maturation of precursor particles (pre-ribosomal particles) containing ribosomal RNA (rRNA) precursors, ribosomal proteins (RPs) and a plethora of assembly factors (AFs). Formation of the earliest precursors of the 60S ribosomal subunit (pre-60S r-particle) is among the least understood stages of ribosome biogenesis. It involves the Npa1 complex, a protein module suggested to play a key role in the early structuring of the pre-rRNA. Npa1 displays genetic interactions with the DExD-box protein Dbp7 and interacts physically with the snR190 box C/D snoRNA. We show here that snR190 functions as a snoRNA chaperone, which likely cooperates with the Npa1 complex to initiate compaction of the pre-rRNA in early pre-60S r-particles. We further show that Dbp7 regulates the dynamic base-pairing between snR190 and the pre-rRNA within the earliest pre-60S r-particles, thereby participating in structuring the peptidyl transferase center (PTC) of the large ribosomal subunit.The Henry/Henras group is supported by grants from ANR (ANR-20-CE12-0026) and funding from CNRS and University of Toulouse. R.A.M. is supported by grants from the Rectorat of Lebanese University. M.J. is supported by a Ph.D. fellowship from the Lebanese University and CIOES Organization. The group of J.d.l.C. is supported by the Spanish Ministry of Science and Innovation [PID2019-103859-GB-I00 AEI/ 10.13039/501100011033], and the Andalusian Regional Government (JA; BIO-271). J.C. was supported by a Ph.D. fellowship (PIF) from the University of Seville, and S.M.-V. is an academic research staff of the JA (PAIDI2020). M.T.B. and K.E.B. are supported by funding from the Deutsche Forschungsgemeinschaft (SFB860) and the University Medical Centre Göttingen

Fatty acid composition in matrix vesicles and in microvilli from femurs of chicken embryos revealed selective recruitment of fatty acids

International audienceHypertrophic chondrocytes participate in matrix mineralization by releasing matrix vesicles (MVs). These MVs, by accumulating Ca2+ and phosphate initiate the formation of hydroxyapatite. To determine the types of lipids essential for mineralization, we analyzed fatty acids (FAs) in MVs, microvilli and in membrane fractions of chondrocytes isolated from femurs of chicken embryos. The FA composition in the MVs was almost identical to that in microvilli, indicating that the MVs originated from microvilli. These fractions contained more monounsaturated FAs especially oleic acid than in membrane homogenates of chondrocytes. They were enriched in 5,8,11-eicosatrienoic acid (20:3n−9), in eicosadienoic acid (20:2n−6), and in arachidonic acid (20:4n−6). In contrast, membrane homogenates from chondrocytes were enriched in 20:1n−9, 18:3n−3, 22:5n−3 and 22:5n−6. Due to their relatively high content in MVs and to their selective recruitment within microvilli from where MV originate, we concluded that 20:2n−6 and 20:3n−9 (pooled values), 18:1n−9 and 20:4n−6 are essential for the biogenesis of MVs and for bone mineralization

Fatty acid composition in matrix vesicles and in microvilli from femurs of chicken embryos revealed selective recruitment of fatty acids

International audienceHypertrophic chondrocytes participate in matrix mineralization by releasing matrix vesicles (MVs). These MVs, by accumulating Ca2+ and phosphate initiate the formation of hydroxyapatite. To determine the types of lipids essential for mineralization, we analyzed fatty acids (FAs) in MVs, microvilli and in membrane fractions of chondrocytes isolated from femurs of chicken embryos. The FA composition in the MVs was almost identical to that in microvilli, indicating that the MVs originated from microvilli. These fractions contained more monounsaturated FAs especially oleic acid than in membrane homogenates of chondrocytes. They were enriched in 5,8,11-eicosatrienoic acid (20:3n−9), in eicosadienoic acid (20:2n−6), and in arachidonic acid (20:4n−6). In contrast, membrane homogenates from chondrocytes were enriched in 20:1n−9, 18:3n−3, 22:5n−3 and 22:5n−6. Due to their relatively high content in MVs and to their selective recruitment within microvilli from where MV originate, we concluded that 20:2n−6 and 20:3n−9 (pooled values), 18:1n−9 and 20:4n−6 are essential for the biogenesis of MVs and for bone mineralization

Arsenic/interferon-a triggered apoptosis in HTLV-I transformed cells is associated with proteasome mediated tax degradation and reversal of NF-κB activation

HTLV-I associated Adult T cell leukemia /lymphoma (ATL) is a malignancy of mature activated T cells resistant to conventional chemotherapy. The viral transactivator oncoprotein Tax plays a critical role in HTLV-I-induced transformation and resistance to apoptosis, through the activation of the NF-KB pathway by inducing IicB-a and IicE'-β degradation. We have previously shown that the combination of arsenic trioxide (As) and interferon-ot (IFN) is highly effective to induce cell cycle arrest and apoptosis in HTLVI positive cells compared to HTLV-1 negative T cells. We have also demonstrated that cell death induction by As and IFN in HTLV-I transformed cells is only partially dépendant upon caspase activation and is not associated with modulation of bcl-2, bax or p 53 expression. In this study, we show that the combination of As and IFN induces the downregulation of Tax by the proteasome in both HTLV-I transformed cells and in T-cdls transiently transfected with Tax. This is associated with an upregulation of iKB-a, tofiβ and iKB-e through inhibition of their proteasomal degradation. Furthermore, As/EN treatment inhibits NF-KB reporter gene induction after Tax transfection and results in a sharp decrease in RelA DNA binding NF-KB complexes in HTLV-I transformed cells due to the cytoplasmic retention of RelA. Although Tax was previously shown to bind proteasome subunits to enhance lKB-a degradation, using kinetic studies we showed that As alone increases lKB-a level before the occurrence of Tax down-regulation. This sugge sts that As and As/IFN alters the proteasome function qualitatively to differentially enhance Tax degradation and inhibit lKB-a degradation. Such specific targeting of the viral oncoprotein by IFN/As treatment, reminiscent of As targeting of PML/RARa in acute promyelocytic leukemia, provides strong rational for combined IFN/As therapy in ATL patients. Indeed, preliminary results of a phase II clinical trial in relapsed/refractory ATL patients are encouraging suggesting the possibility of introducing As in the first line therapy of ATL.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Human T-cell lymphotropic virus type 1–transformed cells induce angiogenesis and establish functional gap junctions with endothelial cells

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New analogues of 13-hydroxyocatdecadienoic acid and 12-hydroxyeicosatetraenoic acid block human blood platelet aggregation and cyclooxygenase-1 activity.

International audienceUNLABELLED: BACKGROUND: Thromboxane A2 is derived from arachidonic acid through the action of cyclooxygenases and thromboxane synthase. It is mainly formed in blood platelets upon activation and plays an important role in aggregation. Aspirin is effective in reducing the incidence of complications following acute coronary syndrome and stroke. The anti-thrombotic effect of aspirin is obtained through the irreversible inhibition of cyclooxygenases. Analogues of 12-hydroxyeicosatetraenoic acid and 13-hydroxyocatdecadienoic acid were shown previously to modulate platelet activation and to block thromboxane receptors. RESULTS AND DISCUSSION: We synthesized 10 compounds based on the structures of analogues of 12-hydroxyeicosatetraenoic acid and 13-hydroxyocatdecadienoic acid and evaluated their effect on platelet aggregation triggered by arachidonic acid. The structure activity relationship was evaluated. Five compounds showed a significant inhibition of platelet aggregation and highlighted the importance of the lipidic hydrophobic hydrocarbon chain and the phenol group. Their IC50 ranged from 7.5 ± 0.8 to 14.2 ± 5.7 μM (Mean ± S.E.M.). All five compounds decreased platelet aggregation and thromboxane synthesis in response to collagen whereas no modification of platelet aggregation in response to thromboxane receptor agonist, U46619, was observed. Using COS-7 cells overexpressing human cyclooxygenase-1, we showed that these compounds are specific inhibitors of cyclooxygenase-1 with IC50 ranging from 1.3 to 12 μM. Docking observation of human recombinant cyclooxygenase-1 supported a role of the phenol group in the fitting of cyclooxygenase-1, most likely related to hydrogen bonding with the Tyr 355 of cyclooxygenase-1. CONCLUSIONS: In conclusion, the compounds we synthesized at first based on the structures of analogues of 12 lipoxygenase metabolites showed a role of the phenol group in the anti-platelet and anti-cyclooxygenase-1 activities. These compounds mediate their effects via blockade of cyclooxygenase-1

GNL3 regulates replication origin firing and protects stalled replication forks

DNA replication by the replisome requires specific proteins that protect replication forks and so prevent the formation of DNA lesions that may damage the genome. Here, we show that human GNL3/nucleostemin, a GTP-binding protein localized in the nucleolus and the nucleoplasm, is a new component of the replisome. Depletion of GNL3 reduces fork speed but increases replication origin firing. When subjected to replication stress, the nascent DNA of GNL3-depleted cells undergoes nuclease-dependent resection, a source of DNA lesions. Inhibition of origin firing decreases this resection, indicating that the increased replication origin firing seen upon GNL3 depletion mainly accounts for the observed DNA resection. We show that GNL3 and DNA replication initiation factor ORC2 interact in the nucleolus, and that GNL3 regulates ORC2 subnuclear localization. The accumulation of GNL3 in the nucleolus is thus required to limit DNA resection in response to replicative stress, potentially through the regulation of ORC2 functions