Synergistic activity of RSL3 and Pyrimethamine to inhibit the proliferation of .

Malaria tropica, caused by (), remains a global health challenge with limited therapeutic options. In mammalian cells, the small-molecule compound RAS-selective lethal 3 (RSL3) induces ferroptosis via lipid peroxidation. In this study, we demonstrate that RSL3 synergizes with Pyrimethamine, an inhibitor of dihydrofolate reductase (DHFR), to suppress parasite proliferation in red blood cells (RBCs).

The protease inhibitor Nirmatrelvir synergizes with inhibitors of GRP78 to suppress SARS-CoV-2 replication.

Nirmatrelvir, the active compound of the drug Paxlovid, inhibits the Main protease of SARS-CoV-2 (M, 3CL, NSP5). Its therapeutic application reduces but does not abolish the progression of COVID-19 in humans. Here we report a strong synergy of Nirmatrelvir with inhibitors of the ER chaperone GRP78 (HSPA5, BiP).

Synergistic interference with SARS-CoV-2 replication by molnupiravir-derived N-hydroxycytidine and inhibitors of CTP synthetase in cell culture.

N-hydroxycytidine (NHC), the active metabolite of molnupiravir, is incorporated into nascent RNA of SARS-CoV-2 and interferes with subsequent virus replication. We have previously described synergy between NHC and inhibitors of dehydroorotate dehydrogenase (DHODH), an enzyme required for pyrimidine synthesis. Upon DHODH inhibition, the lack of endogenous pyrimidines conceivably enhances NHC incorporation.

GANNET53 Part II: A European Phase I/II Trial of the HSP90 Inhibitor Ganetespib in High-Grade Platinum-Resistant Ovarian Cancer-A Study of the GANNET53 Consortium.

Purpose: Mutant p53 stabilized by heat shock protein 90 (HSP90) is a novel target in oncology. The open-label, randomized phase II GANNET53 trial is the first to evaluate the HSP90 inhibitor ganetespib (G) with paclitaxel (P) in platinum-resistant epithelial ovarian cancer (EUDRACT 2013-003868-31; EU FP7 #602602).

Patients And Methods: Patients were randomized 2:1 to receive G + P or P alone until progression.

Myricetin-bound crystal structure of the SARS-CoV-2 helicase NSP13 facilitates the discovery of novel natural inhibitors.

The SARS-CoV-2 helicase NSP13 is a highly conserved and essential component of the viral replication machinery, making it a promising target for antiviral drug development. Here, we present the 2 Å resolution crystal structure of NSP13 bound to the natural flavonoid myricetin, revealing a conserved allosteric binding site. Guided by these structural findings, a virtual screening campaign identified the caffeic acid derivatives rosmarinic acid and chlorogenic acid as potential novel natural inhibitors, which were experimentally validated to inhibit RNA-unwinding activity.

Alternative splicing in the DBD linker region of p63 modulates binding to DNA and iASPP in vitro.

The transcription factor p63 is expressed in many different isoforms as a result of differential promoter use and splicing. Some of these isoforms have very specific physiological functions in the development and maintenance of epithelial tissues and surveillance of genetic integrity in oocytes. The ASPP family of proteins is involved in modulating the transcriptional activity of the p53 protein family members, including p63.

MDM4 exon skipping upon dysfunctional ribosome assembly.

Recent studies revealed how nucleolar stress enhances MDM4 exon skipping and activates p53 via the ribosomal protein L22 (RPL22; eL22). Tumor-associated L22 mutations lead to full-length MDM4 synthesis, overcoming tumor suppression by p53. This forum article explores how MDM4 splicing patterns integrate stress signaling to take p53-dependent cell fate decisions.

Identification of antibody-resistant SARS-CoV-2 mutants via N4-Hydroxycytidine mutagenesis.

Monoclonal antibodies targeting the Spike protein of SARS-CoV-2 are effective against COVID-19 and might mitigate future pandemics. However, their efficacy is challenged by the emergence of antibody-resistant virus variants. We developed a method to efficiently identify such resistant mutants based on selection from mutagenized virus pools.

The ribosomal protein L22 binds the MDM4 pre-mRNA and promotes exon skipping to activate p53 upon nucleolar stress.

The tumor suppressor p53 and its antagonists MDM2 and MDM4 integrate stress signaling. For instance, dysbalanced assembly of ribosomes in nucleoli induces p53. Here, we show that the ribosomal protein L22 (RPL22; eL22), under conditions of ribosomal and nucleolar stress, promotes the skipping of MDM4 exon 6.

Evaluation of N4-hydroxycytidine incorporation into nucleic acids of SARS-CoV-2-infected host cells by direct measurement with liquid chromatography-mass spectrometry.

Molnupiravir, an orally administered prodrug of β-d-N4-hydroxycytidine (NHC), is incorporated into newly synthesized RNA by viral RNA-dependent RNA polymerase (RdRp). It is used for treatment of SARS-CoV-2 infections. Incorporation of NHC triphosphate into viral RNA inhibits replication of the virus, at least in part by introducing deleterious mutations.

Nanobodies to multiple spike variants and inhalation of nanobody-containing aerosols neutralize SARS-CoV-2 in cell culture and hamsters.

The ongoing threat of COVID-19 has highlighted the need for effective prophylaxis and convenient therapies, especially for outpatient settings. We have previously developed highly potent single-domain (VHH) antibodies, also known as nanobodies, that target the Receptor Binding Domain (RBD) of the SARS-CoV-2 Spike protein and neutralize the Wuhan strain of the virus. In this study, we present a new generation of anti-RBD nanobodies with superior properties.

N4-hydroxycytidine, the active compound of Molnupiravir, promotes SARS-CoV-2 mutagenesis and escape from a neutralizing nanobody.

N4-hydroxycytidine (NHC), the active compound of the drug Molnupiravir, is incorporated into SARS-CoV-2 RNA, causing false base pairing. The desired result is an "error catastrophe," but this bears the risk of mutated virus progeny. To address this experimentally, we propagated the initial SARS-CoV-2 strain in the presence of NHC.

The interplay of TARG1 and PARG protects against genomic instability.

The timely removal of ADP-ribosylation is crucial for efficient DNA repair. However, much remains to be discovered about ADP-ribosylhydrolases. Here, we characterize the physiological role of TARG1, an ADP-ribosylhydrolase that removes aspartate/glutamate-linked ADP-ribosylation.

DNA templated Click Chemistry via 5-vinyl-2'-deoxyuridine and an acridine-tetrazine conjugate induces DNA damage and apoptosis in cancer cells.

Aims: Click Chemistry is providing valuable tools to biomedical research, but its direct use in therapies remains nearly unexplored. For cancer treatment, nucleoside analogues (NA) such as 5-vinyl-2'-deoxyuridine (VdU) can be metabolically incorporated into cancer cell DNA and subsequently "clicked" to form a toxic product. The inverse electron-demand Diels-Alder (IEDDA) reaction between VdU and an acridine-tetrazine conjugate (PINK) has previously been used to label cell nuclei of cultured cells.

CDK4/6 inhibition confers protection of normal gut epithelia against gemcitabine and the active metabolite of irinotecan.

Cancer chemotherapy relies on a high ratio of toxicity toward cancer cells vs. nonmalignant cells, making it desirable to protect normal cells. Among the nonmalignant cells, epithelia of the gut belong to the most vulnerable ones toward chemotherapeutics.

MYC multimers shield stalled replication forks from RNA polymerase.

Oncoproteins of the MYC family drive the development of numerous human tumours. In unperturbed cells, MYC proteins bind to nearly all active promoters and control transcription by RNA polymerase II. MYC proteins can also coordinate transcription with DNA replication and promote the repair of transcription-associated DNA damage, but how they exert these mechanistically diverse functions is unknown.

Dipeptidyl peptidase 9 triggers BRCA2 degradation and promotes DNA damage repair.

N-terminal sequences are important sites for post-translational modifications that alter protein localization, activity, and stability. Dipeptidyl peptidase 9 (DPP9) is a serine aminopeptidase with the rare ability to cleave off N-terminal dipeptides with imino acid proline in the second position. Here, we identify the tumor-suppressor BRCA2 as a DPP9 substrate and show this interaction to be induced by DNA damage.

MDM2 binds and ubiquitinates PARP1 to enhance DNA replication fork progression.

The MDM2 oncoprotein antagonizes the tumor suppressor p53 by physical interaction and ubiquitination. However, it also sustains the progression of DNA replication forks, even in the absence of functional p53. Here, we show that MDM2 binds, inhibits, ubiquitinates, and destabilizes poly(ADP-ribose) polymerase 1 (PARP1).

Inhibitors of dihydroorotate dehydrogenase cooperate with molnupiravir and N4-hydroxycytidine to suppress SARS-CoV-2 replication.

The nucleoside analog N4-hydroxycytidine (NHC) is the active metabolite of the prodrug molnupiravir, which has been approved for the treatment of COVID-19. SARS-CoV-2 incorporates NHC into its RNA, resulting in defective virus genomes. Likewise, inhibitors of dihydroorotate dehydrogenase (DHODH) reduce virus yield upon infection, by suppressing the cellular synthesis of pyrimidines.

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Monoclonal immunoglobulins are widely successful as therapeutics and have also been effective in treating COVID-19. However, their production in mammalian cells is expensive and cannot be scaled to meet the demand in a global pandemic. Camelid VH antibodies (also called nanobodies), however, can be manufactured cost-efficiently in bacteria or yeast.

MDM2-Driven Ubiquitination Rapidly Removes p53 from Its Cognate Promoters.

MDM2 is the principal antagonist of the tumor suppressor p53. p53 binds to its cognate DNA element within promoters and activates the transcription of adjacent genes. These target genes include MDM2.

HSP90 Inhibition Synergizes with Cisplatin to Eliminate Basal-like Pancreatic Ductal Adenocarcinoma Cells.

To improve the treatment of pancreatic ductal adenocarcinoma (PDAC), a promising strategy consists of personalized chemotherapy based on gene expression profiles. Investigating a panel of PDAC-derived human cell lines, we found that their sensitivities towards cisplatin fall in two distinct classes. The platinum-sensitive class is characterized by the expression of GATA6, miRNA-200a, and miRNA-200b, which might be developable as predictive biomarkers.

MYCN recruits the nuclear exosome complex to RNA polymerase II to prevent transcription-replication conflicts.

The MYCN oncoprotein drives the development of numerous neuroendocrine and pediatric tumors. Here we show that MYCN interacts with the nuclear RNA exosome, a 3'-5' exoribonuclease complex, and recruits the exosome to its target genes. In the absence of the exosome, MYCN-directed elongation by RNA polymerase II (RNAPII) is slow and non-productive on a large group of cell-cycle-regulated genes.