Single-cell transcriptomics of NRAS-mutated melanoma transitioning to drug resistance reveals P2RX7 as an indicator of early drug response.

Treatment options for patients with NRAS-mutant melanoma are limited and lack an efficient targeted drug combination that significantly increases overall and progression-free survival. In addition, targeted therapy success is hampered by the inevitable emergence of drug resistance. A thorough understanding of the molecular processes driving cancer cells' escape mechanisms is crucial to tailor more efficient follow-up therapies. We performed single-cell RNA sequencing of NRAS-mutant melanoma treated with MEK1/2 plus CDK4/6 inhibitors to decipher transcriptional transitions during the development of drug resistance. Cell lines resuming full proliferation (FACs [fast-adapting cells]) and cells that became senescent (SACs [slow-adapting cells]) over prolonged treatment were identified. The early drug response was characterized by transitional states involving increased ion signaling, driven by upregulation of the ATP-gated ion channel P2RX7. P2RX7 activation was associated with improved therapy responses and, in combination with targeted drugs, could contribute to the delayed onset of acquired resistance in NRAS-mutant melanoma.

CCT196969 effectively inhibits growth and survival of melanoma brain metastasis cells.

Melanomas frequently metastasize to the brain. Despite recent progress in the treatment of melanoma brain metastasis, therapy resistance and relapse of disease remain unsolved challenges. CCT196969 is a SRC family kinase (SFK) and Raf proto-oncogene, serine/threonine kinase (RAF) inhibitor with documented effects in primary melanoma cell lines in vitro and in vivo. Using in vitro cell line assays, we studied the effects of CCT196969 in multiple melanoma brain metastasis cell lines. The drug effectively inhibited proliferation, migration, and survival in all examined cell lines, with viability IC50 doses in the range of 0.18-2.6 µM. Western blot analysis showed decreased expression of p-ERK, p-MEK, p-STAT3 and STAT3 upon CCT196969 treatment. Furthermore, CCT196969 inhibited viability in two B-Raf Proto-Oncogene (BRAF) inhibitor resistant metastatic melanoma cell lines. Further in vivo studies should be performed to determine the treatment potential of CCT196969 in patients with treatment-naïve and resistant melanoma brain metastasis.

Polymeric stationary phases for size exclusion chromatography: A review.

Synthetic and natural macromolecules are commonly used in a variety of fields such as plastics, nanomedicine, biotherapeutics, drug delivery and tissue engineering. Characterising macromolecules in terms of their structural parameters (size, molar mass and distribution, architecture) is key to have a better understanding of their structure-property relationships. Size exclusion chromatography (SEC) is a commonly used technique for polymer characterization since it offers access to the determination of the size of a macromolecule, its molar mass and the molar mass distribution. Moreover, detectors that allow the determination of true molar masses, macromolecule's architecture and the composition of copolymers can be coupled to the chromatographic system. Like other chromatographic techniques, the stationary phase is of paramount importance for efficient SEC separations. This review presents the basic principles for the design of stationary phases for SEC as well as synthetic methods currently used in the field. Current status of fully-porous polymeric stationary phases used in SEC is reviewed and their advantages and limitations are also discussed. Finally, the potential of polymer monoliths in SEC is also covered, highlighting the limitations this column technology could address. However, further development in the polymer structure is needed to consider this column technology in the field of macromolecule separation.

Sleep Counteracts Aging Phenotypes to Survive Starvation-Induced Developmental Arrest in C. elegans.

Sleep is ancient and fulfills higher brain functions as well as basic vital processes. Little is known about how sleep emerged in evolution and what essential functions it was selected for. Here, we investigated sleep in Caenorhabditis elegans across developmental stages and physiological conditions to find out when and how sleep in a simple animal becomes essential for survival. We found that sleep in worms occurs during most stages and physiological conditions and is typically induced by the sleep-active RIS neuron. Food quality and availability determine sleep amount. Extended starvation, which induces developmental arrest in larvae, presents a major sleep trigger. Conserved nutrient-sensing regulators of longevity and developmental arrest, AMP-activated kinase and FoxO, act in parallel to induce sleep during extended food deprivation. These metabolic factors can act in multiple tissues to signal starvation to RIS. Although sleep does not appear to be essential for a normal adult lifespan, it is crucial for survival of starvation-induced developmental arrest in larvae. Rather than merely saving energy for later use, sleep counteracts the progression of aging phenotypes, perhaps by allocating resources. Thus, sleep presents a protective anti-aging program that is induced by nutrient-sensing longevity pathways to survive starvation-induced developmental arrest. All organisms are threatened with the possibility of experienced famine in their life, which suggests that the molecular coupling of starvation, development, aging, and sleep was selected for early in the evolution of nervous systems and may be conserved in other species, including humans.

Determination of molar masses of macromolecules by size exclusion chromatography-light scattering not requiring knowledge of refractive index increments.

A new approach for the calibration of SEC-light scattering (SEC-LS) setups is proposed, which requires solely the molar mass of a reference polymer. Neither the specific refractive index increment of the calibrant nor of the analyte is required. Comparison of the molar masses derived in different solvents for a large number of chemically different polymers shows that the new approach yields the same molar masses as if molar masses were derived using dn/dc to calibrate the light scattering setup. The approach therefore allows easier determination of molar masses by SEC-LS.

Dissecting miRNA gene repression on single cell level with an advanced fluorescent reporter system.

Despite major advances on miRNA profiling and target predictions, functional readouts for endogenous miRNAs are limited and frequently lead to contradicting conclusions. Numerous approaches including functional high-throughput and miRISC complex evaluations suggest that the functional miRNAome differs from the predictions based on quantitative sRNA profiling. To resolve the apparent contradiction of expression versus function, we generated and applied a fluorescence reporter gene assay enabling single cell analysis. This approach integrates and adapts a mathematical model for miRNA-driven gene repression. This model predicts three distinct miRNA-groups with unique repression activities (low, mid and high) governed not just by expression levels but also by miRNA/target-binding capability. Here, we demonstrate the feasibility of the system by applying controlled concentrations of synthetic siRNAs and in parallel, altering target-binding capability on corresponding reporter-constructs. Furthermore, we compared miRNA-profiles with the modeled predictions of 29 individual candidates. We demonstrate that expression levels only partially reflect the miRNA function, fitting to the model-projected groups of different activities. Furthermore, we demonstrate that subcellular localization of miRNAs impacts functionality. Our results imply that miRNA profiling alone cannot define their repression activity. The gene regulatory function is a dynamic and complex process beyond a minimalistic conception of "highly expressed equals high repression".

Characterization of poly(methyl methacrylate)-graft-poly(styrene)s using various chromatographic techniques.

Two graft copolymer samples of identical average composition were synthesized by grafting living polystyrene anions onto a broadly distributed PMMA backbone. Size exclusion chromatography (SEC) with only RI-detection, SEC with viscometry and light scattering detection, SEC with UV and RI dual detection, gradient chromatography and 2-dimensional chromatography were applied to compare the information that can be obtained by the different techniques. While only limited information was retrieved by conventional SEC or SEC with molar mass sensitive detection, SEC with UV and RI revealed different chemical heterogeneity of the samples. Using gradient chromatography and 2-dimensional chromatography it was possible to identify non-grafted side chains and unreacted parent PMMA besides the actual graft copolymer molecules. While in one sample a heavily grafted product was formed besides non-grafted PMMA, the second sample did not contain ungrafted PMMA but a graft product of lower grafting density. The different product distributions were explained by the different synthetic procedures.

Crystal structure of 11-[4-(hex-yloxy)phen-yl]-1,2,4-triazolo[4,3-a][1,10]phenanthroline.

The title compound, C25H24N4O, was prepared from 2-chloro-phenanthroline and hexyl-oxyphenyl-tetra-zole. The main difference between the two independent mol-ecules (A and B) in the asymmetric unit is the orientation of the all-anti-configured hex-yloxy chain: in A the C-O-C-C torsion angle is 175.9 (2)° whereas it is -88.3 (3)° in B. The benzene substitution in the bay of the triazolophenanthroline results in a helical distorsion of the heterocyclic core, the dihedral angles between the mean planes formed by quinoline and benzotriazole ring systems are 13.73 (9) for mol-ecule A and 14.87 (8)° for B. The dihedral angles between the triazole ring and the attached benzene ring are 45.87 (15) in A and 53.93 (14)° in B. The angular annulation of four rings and the benzene substituent results in a helical distortion of the aromatic framework. The crystal is formed from layers composed of centrosymmetric pairs of A 2, B 2 mol-ecules with inter-digitating alkyl chains.

6-Chloro-3-(3-methyl-phen-yl)-1,2,4-triazolo[4,3-b]pyridazine.

The title compound, C(12)H(9)ClN(4), was prepared from dichloro-pyridazine and tolyl-tetra-zole in a nucleophilic biaryl coupling followed by thermal ring transformation. The mol-ecule is essentially planar (r.m.s. deviation for all non-H atoms = 0.036 Å) and an intra-molecular C-H⋯N hydrogen bond occurs. In the crystal, the mol-ecules form dimers connected via π-π inter-actions [centroid-centroid distance = 3.699 (2) Å], which are further connected to neighbouring mol-ecules via C-H-N bonds. The bond lengths in the pyridazine ring system indicate a strong localization of the double bonds and there is a weak C-Cl bond [1.732 (3) Å].

5-Methyl-3-(3-methyl-phen-yl)-7-phenyl-1,2,4-triazolo[4,3-c]pyrimidine.

The title compound, C(19)H(16)N(4), is one of the few known 3,7-diaryl-1,2,4-triazolo[4,3-c]pyrimidines. The triazolopyrimidine unit is essentially planar (r.m.s. deviation = 0.048 Å). The phenyl ring and the heterocyclic core subtend a dihedral angle of only 15.09 (6)°, whereas the m-tolyl ring is twisted by 71.80 (6)° out of the plane of the triazole ring. Two C-H⋯N hydrogen bonds and π-π stacking inter-actions [centroid-centroid distance = 3.7045 (8) Å] stabilize the crystal packing.