ABSTRACT
Microtubule dynamics are critical for spindle assembly and chromosome segregation during cell division. Pharmacological inhibition of microtubule dynamics in cells causes prolonged mitotic arrest, resulting in apoptosis, an approach extensively employed in treating different types of cancers. The present study reports the synthesis of thirty-two novel bis-amides (SSE1901-SSE1932) and the evaluation of their antiproliferative activities. N-(1-oxo-3-phenyl-1-(phenylamino)propan-2-yl)benzamide (SSE1917) exhibited the most potent activity with GI50 values of 0.331 ± 0.01 µM in HCT116 colorectal and 0.48 ± 0.27 µM in BT-549 breast cancer cells. SSE1917 stabilized microtubules in biochemical and cellular assays, bound to taxol site in docking studies, and caused aberrant mitosis and G2/M arrest in cells. Prolonged treatment of cells with the compound increased p53 expression and triggered apoptotic cell death. Furthermore, SSE1917 suppressed the growth of both mouse and patient-derived human colon cancer organoids, highlighting its potential therapeutic value as an anticancer agent.
Subject(s)
Antineoplastic Agents , Tubulin Modulators , Tubulin , Animals , Humans , Mice , Amides/pharmacology , Antineoplastic Agents/pharmacology , Antineoplastic Agents/metabolism , Apoptosis , Cell Line, Tumor , Cell Proliferation , Microtubules/metabolism , Mitosis , Tubulin/drug effects , Tubulin/metabolism , Tubulin Modulators/chemistry , Tubulin Modulators/pharmacologyABSTRACT
Tropical rainforests are among the most diverse biomes on Earth. While species inventories are far from complete for any tropical rainforest, even less is known about the intricate species interactions that form the basis of these ecological communities. One fascinating but poorly studied example are the symbiotic associations between army ants and their rich assemblages of parasitic arthropod guests. Hundreds of these guests, or myrmecophiles, have been taxonomically described. However, because previous work has mainly been based on haphazard collections from disjunct populations, it remains challenging to define species boundaries. We therefore know little about the species richness, abundance and host specificity of most guests in any given population, which is crucial to understand co-evolutionary and ecological dynamics. Here, we report a quantitative community survey of myrmecophiles parasitizing the six sympatric Eciton army ant species in a Costa Rican rainforest. Combining DNA barcoding with morphological identification of over 2,000 specimens, we discovered 62 species, including 49 beetles, 11 flies, one millipede and one silverfish. At least 14 of these species were new to science. Ecological network analysis revealed a clear signal of host partitioning, and each Eciton species was host to both specialists and generalists. These varying degrees in host specificities translated into a moderate level of network specificity, highlighting the system's level of biotic pluralism in terms of biodiversity and interaction diversity. By providing vouchered DNA barcodes for army ant guest species, this study provides a baseline for future work on co-evolutionary and ecological dynamics in these species-rich host-symbiont networks across the Neotropical realm.
Subject(s)
Ants , Coleoptera , Animals , Ants/genetics , Biodiversity , Host Specificity/genetics , Symbiosis/geneticsABSTRACT
The Wnt signalling pathways are of great importance in embryonic development and oncogenesis. Canonical and non-canonical Wnt signalling pathways are known, with the canonical (or ß-catenin dependent) pathway being perhaps the best studied of these. While structural knowledge of proteins and interactions involved in canonical Wnt signalling has accumulated over the past 20 years, the pace of discovery has increased in recent years, with the structures of several key proteins and assemblies in the pathway being released. In this review, we provide a brief overview of canonical Wnt signalling, followed by a comprehensive overview of currently available X-ray, NMR and cryoEM data elaborating the structures of proteins and interactions involved in canonical Wnt signalling. While the volume of structures available is considerable, numerous gaps in knowledge remain, particularly a comprehensive understanding of the assembly of large multiprotein complexes mediating key aspects of pathway, as well as understanding the structure and activation of membrane receptors in the pathway. Nonetheless, the presently available data affords considerable opportunities for structure-based drug design efforts targeting canonical Wnt signalling.
Subject(s)
Wnt Signaling Pathway , Animals , Cell Nucleus/metabolism , Drug Design , Humans , Protein Conformation , Receptors, Cell Surface/metabolism , Wnt Proteins/chemistry , Wnt Proteins/metabolismABSTRACT
The Class F G protein-coupled receptors (GPCRs) include Smoothened and the ten Frizzled receptors, which are major cell membrane receptors in the Hedgehog and Wnt signalling pathways respectively and of enormous interest in embryonic development and as therapeutic targets in cancer. Recent crystal structures of Smoothened provide the opportunity to investigate the structural biology of Class F GPCRs in more detail, in turn, informing the development of therapeutics. A key question in this area is how one receptor may trigger distinct pathways - particularly relevant for Wnt signalling, in which signals may be transduced from a Frizzled via Dishevelled or G proteins, depending on the context. In this study, we employ adiabatic biased molecular dynamics and umbrella sampling to investigate the activation of Smoothened and Frizzled-7 in both the native state and bound to endogenous ligands, as well as how the clinically used Smoothened antagonist vismodegib alters this signalling. The results highlight key energetic barriers in the activation of these receptors, and the molecular features of the receptors mediating these barriers, demonstrating our approach as a robust means of investigating signalling through these receptors.
Subject(s)
Receptors, G-Protein-CoupledABSTRACT
BACKGROUND: Immediate implant placement in the presence of intact extraction alveoli has frequently been reported, while hardly any reports on immediate implant placement in missing buccal bone can be found in literature. OBJECTIVES: This pilot study evaluates esthetic outcome and soft and hard tissue level changes of immediate implant placement with immediate provisionalization in patients with partially/completely missing buccal bone without any further augmentation procedure in the maxillary anterior zone. MATERIAL AND METHODS: Twelve patients (TG) with partially to completely missing buccal bone designated for extraction and flapless immediate implant insertion in the anterior zone of the maxilla were included. Patients randomly selected out of a larger group of patients with immediate implants with intact alveoli served as controls (CG). Immediate provisionalization was done without any further augmentation of the alveolar ridge. Marginal hard and soft tissue levels, PES, and implant success were evaluated during a 1-year observation period. RESULTS: The defect of the buccal alveolar bone was 4.96 mm (min., 2.26 mm; max., 9.68 mm) and the mean mesio-distal extension 4.25 mm (min., 3.2 mm; max., 5.91 mm). Preoperative PES differed significantly between TG (9.68) and CG (12.25) and improved in TG postoperatively with no significant difference to CG after 1 year (TG, 10.91; CG, 11.3). The buccal soft tissue level remained almost unchanged over the observation period (TG preop, 0.86 mm ± 0.90 mm; 1 year, 0.91 mm ± 0.96 mm; CG preop, 0.98 mm ± 0.87 mm; 1 year, 0.98 mm ± 0.87 mm and did not show any correlation with either the mesial/distal bone level or the initial buccal vertical defect at any point of time. CONCLUSIONS: These clinical results provide evidence that immediate implant placement without additional augmentation, but with immediate provisionalization might be a viable treatment alternative even with missing buccal plate in the esthetic maxillary zone.
Subject(s)
Dental Implantation, Endosseous , Dental Implants , Gingival Recession , Immediate Dental Implant Loading , Esthetics, Dental , Humans , Maxilla , Pilot Projects , Treatment OutcomeABSTRACT
Several proteins other than the frizzled receptors (Fzd) and the secreted Frizzled-related proteins (sFRP) contain Fzd-type cysteine-rich domains (CRD). We have termed these domains "putative Fzd-type CRDs", as the relevance of Wnt signalling in the majority of these is unknown; the RORs, an exception to this, are well known for mediating non-canonical Wnt signalling. In this study, we have predicted the likely binding affinity of all Wnts for all putative Fzd-type CRDs. We applied both our previously determined WntâFzd CRD binding affinity prediction model, as well as a newly devised model wherein the lipid term was forced to contribute favourably to the predicted binding energy. The results obtained from our new model indicate that certain putative Fzd CRDs are much more likely to bind Wnts, in some cases exhibiting selectivity for specific Wnts. The results of this study inform the investigation of Wnt signalling modulation beyond Fzds and sFRPs.
Subject(s)
Cysteine , Frizzled Receptors/chemistry , Frizzled Receptors/metabolism , Protein Interaction Domains and Motifs , Wnt Proteins/metabolism , Cysteine/chemistry , Humans , Models, Molecular , Protein Binding , Protein Multimerization , Signal TransductionABSTRACT
Wnt signaling pathways are of significant interest in development and oncogenesis. The first step in these pathways typically involves the binding of a Wnt protein to the cysteine-rich domain (CRD) of a Frizzled receptor. Wnt-Frizzled interactions can be antagonized by secreted Frizzled-related proteins (SFRPs), which also contain a Frizzled-like CRD. The large number of Wnts, Frizzleds, and SFRPs, as well as the hydrophobic nature of Wnt, poses challenges to laboratory-based investigations of interactions involving Wnt. Here, utilizing structural knowledge of a representative Wnt-Frizzled CRD interaction, as well as experimentally determined binding affinities for a selection of Wnt-Frizzled CRD interactions, we generated homology models of Wnt-Frizzled CRD interactions and developed a quantitative structure-activity relationship for predicting their binding affinities. The derived model incorporates a small selection of terms derived from scoring functions used in protein-protein docking, as well as an energetic term considering the contribution made by the lipid of Wnt to the Wnt-Frizzled binding affinity. Validation with an external test set suggests that the model can accurately predict binding affinity for 75% of cases and that the error associated with the predictions is comparable with the experimental error. The model was applied to predict the binding affinities of the full range of mouse and human Wnt-Frizzled and Wnt-SFRP interactions, indicating trends in Wnt binding affinity for Frizzled and SFRP CRDs. The comprehensive predictions made in this study provide the basis for laboratory-based studies of previously unexplored Wnt-Frizzled and Wnt-SFRP interactions, which, in turn, may reveal further Wnt signaling pathways.
Subject(s)
Frizzled Receptors , Molecular Docking Simulation , Wnt Proteins , Wnt Signaling Pathway/physiology , Animals , Frizzled Receptors/genetics , Frizzled Receptors/metabolism , Humans , Protein Binding , Protein Domains , Wnt Proteins/chemistry , Wnt Proteins/genetics , Wnt Proteins/metabolismABSTRACT
Malignant mesothelioma (MM) is an aggressive cancer, characterized by rapid progression, along with late metastasis and poor patient prognosis. It is resistant to many forms of standard anti-cancer treatment. In this study, we determined the effect of secreted frizzled-related protein 4 (sFRP4), a Wnt pathway inhibitor, on cancer cell proliferation and metabolism using the JU77 mesothelioma cell line. Treatment with sFRP4 (250 pg/ml) resulted in a significant reduction of cell proliferation. The addition of the Wnt activator Wnt3a (250 pg/ml) or sFRP4 had no significant effect on ATP production and glucose utilisation in JU77 cells at both the 24 and 48 h time points examined. We also examined their effect on Akt and Glycogen synthase kinase-3 beta (GSK3ß) phosphorylation, which are both important components of Wnt signalling and glucose metabolism. We found that protein phosphorylation of Akt and GSK3ß varied over the 24h and 48 h time points, with constitutive phosphorylation of Akt at serine 473 (pAkt) decreasing to its most significant level when treated with Wnt3a+sFRP4 at the 24h time point. A significant reduction in the level of Cytochrome c oxidase was observed at the 48 h time point, when sFRP4 and Wnt3a were added in combination. We conclude that sFRP4 may function, in part, to reduce/alter cancer cell metabolism, which may lead to sensitisation of cancer cells to chemotherapeutics, or even cell death.
Subject(s)
Lung Neoplasms/metabolism , Mesothelioma/metabolism , Proto-Oncogene Proteins/metabolism , Wnt Signaling Pathway/physiology , Apoptosis/physiology , Cell Line, Tumor , Cell Proliferation/physiology , Glycogen Synthase Kinase 3/metabolism , Glycogen Synthase Kinase 3 beta , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/pathology , Mesothelioma/drug therapy , Mesothelioma/pathology , Mesothelioma, Malignant , Phosphorylation , Proto-Oncogene Proteins/antagonists & inhibitorsABSTRACT
Secreted frizzled-related protein 4 (SFRP4) is a glycoprotein that acts as an antagonist of Wnt ligands, causing inhibition of the canonical Wnt signalling pathway. First noticed due to high expression levels during times of increased apoptosis, SFRP4 has been implicated in cell proliferation and differentiation and plays an important role in carcinogenesis. Many tumours such as endometrial, cervical, ovarian, prostate, bladder, colorectal, mesothelioma, pancreatic, renal, and oesophageal tumours are characterised by aberrant promoter hypermethylation, which causes variations in the expression level of SFRP4 when compared to normal cells. Combined experimental data appear to confirm the suggested role of SFRP4 as a local initiator of apoptosis; however, increased SFRP4 expression may not always correlate with an increase in apoptosis, possibly due to the complex interactions between different signalling pathways. SFRP4 can be explored for its use in novel therapeutic modalities as well as being a potential diagnostic biomarker.
Subject(s)
Apoptosis , Neoplasms/metabolism , Proto-Oncogene Proteins/metabolism , Animals , Humans , Neoplasms/pathology , Proto-Oncogene Proteins/physiologyABSTRACT
The barrel fill level is defined as the fraction of the free available volume for a given screw configuration that is occupied by the wet material and is an interplay of the material throughput, screw speed, screw setup, barrel length of the twin-screw granulator used and the properties of the starting material. The fill level has a major impact on mixing and densification of the wetted mass and thus on the granules produced. It influences the twin-screw granulation process accordingly. In the current study, a model has been developed which is predictive in terms of material hold-ups in the barrel at various process settings by considering the geometries of the different screw elements in a configuration and the conveying velocity of the wet mass through the barrel. The model was checked on two granulators of different dimensions with various screw configurations, different materials and at different process settings. The model represents a step forward in predicting the barrel fill level but further research with a broader spectrum of materials, screw configurations and process settings is still needed and additional twin-screw granulators of other dimensions must be investigated.
ABSTRACT
BACKGROUND: The present retrospective study investigates implant retention time in patients who had experienced multiple implant failures and explores possible risk factors. MATERIALS AND METHODS: Patients who underwent placement of at least two implants and experienced failure of two or more implants between 2004 and 2022 were included in the study population. Both patient- and implant-related risk factors, including age, sex, medical history, medication intake, smoking, alcohol consumption, implant properties and anatomical and surgical factors, were evaluated. Descriptive analysis and univariate and multivariate statistical analysis were performed to assess implant retention time and failure risk, with the level of statistical significance set at 0.05. RESULTS: A total of 371 patients (178 men and 193 women, median age 63 years) with 3,141 implants were included in the analysis (3.14% of all patients treated since 2004). Out of these implants, 1,090 failures were observed (59.01% of all failed implants at the Academy of Oral Implantology, Vienna, Austria), with a median retention time of 108.11 months. Patients who lost teeth due to periodontitis did not show a tendency towards early implant failure (P > 0.001). Nicotine consumption (P < 0.001), age < 50 years and > 70 years (P < 0.001), maxillary location (P = 0.05), transgingival healing (P < 0.001), no provisional restoration (P = 0.035) and short implant length (P < 0.001) were associated with statistically significantly shorter implant retention times. CONCLUSIONS: Patients with multiple implant failures displayed cluster behaviour and had a median implant retention time of 9 years. Smoking, short implant length, single-stage surgery and immediate loading were all associated with a higher risk of failure, whereas age between 50 and 70 years and tooth loss due to periodontitis were associated with a longer implant retention time.
Subject(s)
Dental Implants , Periodontitis , Male , Humans , Female , Middle Aged , Aged , Dental Implants/adverse effects , Dental Implantation, Endosseous , Retrospective Studies , Follow-Up Studies , Dental Prosthesis Design , Risk Factors , Periodontitis/epidemiology , Periodontitis/complicationsABSTRACT
Bactofilins have emerged as a widespread family of cytoskeletal proteins with important roles in bacterial morphogenesis, but their precise mode of action is still incompletely understood. In this study, we identify the bactofilin cytoskeleton as a key regulator of cell growth in the stalked budding alphaproteobacterium Hyphomonas neptunium. We show that, in this species, bactofilin polymers localize dynamically to the stalk base and the bud neck, with their absence leading to unconstrained growth of the stalk and bud compartments, indicating a central role in the spatial regulation of cell wall biosynthesis. Database searches reveal that bactofilin genes are often clustered with genes for cell wall hydrolases of the M23 peptidase family, suggesting a functional connection between these two types of proteins. In support of this notion, we find that the H. neptunium M23 peptidase homolog LmdC interacts directly with bactofilin in vitro and is required for proper cell shape in vivo. Complementary studies in the spiral-shaped alphaproteobacterium Rhodospirillum rubrum again reveal a close association of its bactofilin and LmdC homologs, which co-localize at the inner curve of the cell, modulating the degree of cell curvature. Collectively, these findings demonstrate that bactofilins and M23 peptidases form a conserved functional module that promotes local changes in the mode of cell wall biosynthesis, thereby driving cell shape determination in morphologically complex bacteria.
Subject(s)
Bacterial Proteins , Endopeptidases , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Cytoskeleton/metabolism , Bacteria/metabolism , Cytoskeletal Proteins/metabolismABSTRACT
Members of the alphaproteobacterial order Rhodobacterales are metabolically diverse and highly abundant in the ocean. They are becoming increasingly interesting for marine biotechnology, due to their ecological adaptability, wealth of versatile low-copy-number plasmids, and their ability to produce secondary metabolites. However, molecular tools for engineering strains of this bacterial lineage are limited. Here, we expand the genetic toolbox by establishing standardized, modular repABC-based plasmid vectors of four well-characterized compatibility groups from the Roseobacter group applicable in the Rhodobacterales, and likely in further alphaproteobacterial orders (Hyphomicrobiales, Rhodospirillales, Caulobacterales). We confirmed replication of these newly constructed pABC vectors in two members of Rhodobacterales, namely, Dinoroseobacter shibae DFL 12 and Rhodobacter capsulatus B10S, as well as in two members of the alphaproteobacterial order Hyphomicrobiales (synonym: Rhizobiales; Ensifer meliloti 2011 and "Agrobacterium fabrum" C58). Maintenance of the pABC vectors in the biotechnologically valuable orders Rhodobacterales and Hyphomicrobiales facilitates the shuttling of genetic constructs between alphaproteobacterial genera and orders. Additionally, plasmid replication was verified in one member of Rhodospirillales (Rhodospirillum rubrum S1) as well as in one member of Caulobacterales (Caulobacter vibrioides CB15N). The modular construction of pABC vectors and the usage of four compatible replication systems, which allows their coexistence in a host cell, are advantageous features for future implementations of newly designed synthetic pathways. The vector applicability was demonstrated by functional complementation of a nitrogenase mutant phenotype by two complementary pABC-based plasmids in R. capsulatus.
Subject(s)
Alphaproteobacteria , Genetic Vectors , Plasmids , Plasmids/genetics , Genetic Vectors/genetics , Alphaproteobacteria/genetics , Host Specificity/geneticsABSTRACT
Microtubules are dynamic structures that form spindle fibers during cell division; pharmacological inhibition of microtubule dynamics arrests cells in mitosis, leading to apoptosis, and they have been extensively used to treat various cancers. However, the efficacy of such drugs is often limited by multidrug resistance. This study synthesized and evaluated 30 novel derivatives of podophyllotoxin, a natural antimitotic compound, for their antiproliferative activities. Compound SSE1806 exhibited the most potent antiproliferative activity with GI50 values ranging from 1.29 ± 0.01 to 21.15 ± 2.1 µM in cancer cell lines of different origins; it directly inhibited microtubule polymerization, causing aberrant mitosis and G2/M arrest. Prolonged treatment with SSE1806 increased p53 expression, induced cell death in monolayer cultures, and reduced the growth of mouse- and patient-derived human colon cancer organoids. Importantly, SSE1806 overcame multidrug resistance in a cell line overexpressing MDR-1. Thus, SSE1806 represents a potential anticancer agent that can overcome multidrug resistance.
ABSTRACT
Army ants provide nourishment to a large variety of animals. This includes birds that feed on animals flushed out by army ant raids, symbiotic arthropods that consume the ants' prey or their brood, and other arthropods that scavenge on army ant refuse deposits. The latter have not received much attention, and the few published studies lack detailed species identifications. Here we provide a first systematic inventory of the beetle fauna associated with refuse deposits of Eciton army ants, with a focus on Eciton burchellii. We collected 8364 adult beetles, 511 larvae, and 24 eggs from 34 deposits at La Selva Biological Station, Costa Rica. We used a combination of DNA barcoding and morphology to identify a subset of 436 specimens to species level. The samples included several new species, and we here formally describe two water scavenger beetles (Hydrophilidae). Refuse deposits harbored a diverse beetle fauna. The identified subset consisted of 91 beetle species from 12 families, with rove beetles being the most abundant and diverse visitors. Of the 85 species found with E. burchellii, 50 species were collected from only one or two refuse deposits. Conversely, seven species were found in 10 or more refuse deposits, indicating a certain level of habitat specialization. We matched adults and immatures for 22 beetle species via DNA barcodes, demonstrating that army ant middens also serve as a beetle nursery. The present survey highlights the significant ecological function of army ants as promoters of biodiversity and their status as keystone species in tropical rainforests.
ABSTRACT
Alternative splicing is a process by which a single gene is able to encode multiple different protein isoforms. It is regulated by the inclusion or exclusion of introns and exons that are joined in different patterns prior to protein translation, thus enabling transcriptomic and proteomic diversity. It is now widely accepted that alternative splicing is dysregulated across nearly all cancer types. This widespread dysregulation means that nearly all cellular processes are affected - these include processes synonymous with the hallmarks of cancer - evasion of apoptosis, tissue invasion and metastasis, altered cellular metabolism, genome instability and drug resistance. Emerging evidence indicates that the dysregulation of alternative splicing also promotes a permissive environment for increased tumour heterogeneity and cellular plasticity. These are fundamental regulators of a patient's response to therapy. In this Review, we introduce the mechanisms of alternative splicing and the role of aberrant splicing in cancer, with particular focus on newfound evidence of alternative splicing promoting tumour heterogeneity, cellular plasticity and altered metabolism. We discuss recent in vivo models generated to study alternative splicing and the importance of these for understanding complex tumourigenic processes. Finally, we review the effects of alternative splicing on immune evasion, cell death and genome instability, and how targeting these might enhance therapeutic efficacy.
Subject(s)
Alternative Splicing , Neoplasms , Alternative Splicing/genetics , Carcinogenesis/genetics , Humans , Introns , Neoplasms/genetics , Neoplasms/pathology , Neoplasms/therapy , Proteomics , RNA SplicingABSTRACT
PURPOSE: The aim of this pilot exploratory cohort study was to assess the value of buccal augmentation in immediate implant placement and immediate restoration of anterior teeth in maxillae with missing buccal lamellar bone with regard to esthetic parameters, as well as soft and hard tissue level changes. MATERIALS AND METHODS: This study compared three groups of 10 patients each with immediate implant placement and immediate restoration in the anterior maxilla: (1) patients with partially to totally missing buccal bone with simultaneous augmentation with bovine collagen (test group augmented [TGA]); (2) patients with partially to totally missing buccal bone without augmentation (test group nonaugmented [TNA]); and (3) patients with intact buccal lamellar bone (control group [CG]). The pink esthetic score (PES) and the course of the peri-implant bone level after 1, 3, and 12 months were used as assessment criteria. RESULTS: After 12 months, the PES in the TGA was assessed as being better than it was preoperatively (mean ± SD: 8 ± 3.09 vs 9.25 ± 3.01, respectively, P = .8243), while it remained almost identical in the other two groups (TNA = 8.75 ± 2.7 vs 8.6 ± 3.3, P = .4098; CG = 10.6 ± 2.41 vs 10.6 ± 2.22, P = .7085). A significant difference among the PES values of the three groups was not observed at any point in time (preoperative: P = .118, 12 months: P = .383). In total, the TNA and CG showed an improvement in 3 out of 7 parameters of the PES after 12 months, while this was the case in 5 out of 7 parameters in the TGA. No significant difference among the three groups could be seen at any time point regarding peri-implant bone level. In the CG and TGA patients, a nonsignificant improvement in peri-implant bone level was seen after 12 months (respectively: 1.6 mm to 0.99 mm; P = .08068; 1.89 mm to 1.73 mm; P = .5866). In contrast, TNA patients showed a nonsignificant deterioration vs the postoperative situation (1.16 mm to 1.45 mm; P = .08208). CONCLUSION: Within the limitations of this pilot study, it can be concluded that a missing buccal lamellar bone appears to be no contraindication for immediate implant placement and immediate restoration, provided the baseline esthetic situation is accepted. As compared to the nonaugmented defect group or the group with intact lamellar bone, neither the esthetic nor the radiologic results could be improved significantly by augmentation with bovine collagen.
Subject(s)
Dental Implants, Single-Tooth , Dental Implants , Immediate Dental Implant Loading , Animals , Cattle , Cohort Studies , Dental Implantation, Endosseous/methods , Esthetics, Dental , Humans , Immediate Dental Implant Loading/methods , Maxilla/surgery , Pilot Projects , Treatment OutcomeABSTRACT
Tumour cell plasticity is a major barrier to the efficacy of targeted cancer therapies but the mechanisms that mediate it are poorly understood. Here, we identify dysregulated RNA splicing as a key driver of tumour cell dedifferentiation in colorectal cancer (CRC). We find that Apc-deficient CRC cells have dysregulated RNA splicing machinery and exhibit global rewiring of RNA splicing. We show that the splicing factor SRSF1 controls the plasticity of tumour cells by controlling Kras splicing and is required for CRC invasion in a mouse model of carcinogenesis. SRSF1 expression maintains stemness in human CRC organoids and correlates with cancer stem cell marker expression in human tumours. Crucially, partial genetic downregulation of Srsf1 does not detrimentally affect normal tissue homeostasis, demonstrating that tumour cell plasticity can be differentially targeted. Thus, our findings link dysregulation of the RNA splicing machinery and control of tumour cell plasticity.
Subject(s)
Cell Plasticity , Colorectal Neoplasms , Animals , Carcinogenesis/genetics , Carcinogenesis/metabolism , Cell Plasticity/genetics , Colorectal Neoplasms/pathology , Gene Expression Regulation, Neoplastic , Mice , RNA Splicing/genetics , Serine-Arginine Splicing Factors/genetics , Serine-Arginine Splicing Factors/metabolismABSTRACT
The binders povidone (Kollidon 30), copovidone (Kollidon VA64), hypromellose (Pharmacoat 606), and three types of hyprolose (HPC SSLSFP, HPC SSL, and HPC SLFP) were evaluated regarding their suitability in twin-screw wet granulation. Six mixtures of lactose and binder as well as lactose without binder were twin-screw granulated with demineralized water at different barrel fill levels and subsequently tableted. A screening run with HPC SSL determined the amount of water as an influential parameter for oversized agglomerates. Subsequent examination of different binders, especially Kollidon 30 and Kollidon VA64 resulted in large granules. All binders, except Pharmacoat 606, led to a reduction of fines compared to granulation without a binder. The molecular weight of applied hyproloses did not appear as influential. Tableting required an upstream sieving step to remove overlarge granules. Tableting was possible for all formulations at sufficient compression pressure. Most binders resulted in comparable tensile strengths, while Pharmacoat 606 led to lower and lactose without a binder to the lowest tensile strength. Tablets without a binder disintegrated easily, whereas binder containing tablets of sufficient tensile strength often nearly failed or failed the disintegration test. Especially tablets containing Pharmacoat 606 and HPC SLFP disintegrated too slowly.
ABSTRACT
Current therapeutic options for treating colorectal cancer have little clinical efficacy and acquired resistance during treatment is common, even following patient stratification. Understanding the mechanisms that promote therapy resistance may lead to the development of novel therapeutic options that complement existing treatments and improve patient outcome. Here, we identify RAC1B as an important mediator of colorectal tumourigenesis and a potential target for enhancing the efficacy of EGFR inhibitor treatment. We find that high RAC1B expression in human colorectal cancer is associated with aggressive disease and poor prognosis and deletion of Rac1b in a mouse colorectal cancer model reduces tumourigenesis. We demonstrate that RAC1B interacts with, and is required for efficient activation of the EGFR signalling pathway. Moreover, RAC1B inhibition sensitises cetuximab resistant human tumour organoids to the effects of EGFR inhibition, outlining a potential therapeutic target for improving the clinical efficacy of EGFR inhibitors in colorectal cancer.