Discovery and characterization of novel potent BCR-ABL degraders by conjugating allosteric inhibitor.

The oncogenic fusion protein BCR-ABL is the driving force of leukemogenesis in chronic myeloid leukemia (CML). Despite the great advance in CML treatment through the application of tyrosine kinase inhibitors (TKIs) against BCR-ABL, disease recurrence after TKI discontinuation and clinical resistance mainly due to BCR-ABL mutations continue to be an issue. Herein we report our efforts to synthesize a novel series of CRBN-recruiting proteolysis-targeting chimeras (PROTACs) targeting BCR-ABL based on the allosteric inhibitor asciminib. Our efforts have led to the discovery of compound 30 (SIAIS100) through extensive SAR studies by the optimization of linker parameters as well as linker attachment points of both target-binding warhead and CRBN ligands, which exhibited the most potent degradative activity with a DC50 value of 2.7 nM and Dmax of 91.2% against BCR-ABL and has an IC50 value of 12 nM in BCR-ABL + K562 cells. The binding model and the stability evaluation of 30-induced ternary complex formation were also elucidated through computational simulations. Furthermore, 30 induced sustained and robust BCR-ABL degradation and maintained the efficacy for 96 h post-washout. Moreover, the proteomics analysis showed that 30 degraded BCR-ABL and three CRBN's neo-substrates, including IKZF1, IKZF3, and ZFP91. Additionally, 30 also exerted degradative activity against a panel of clinically relevant resistance-conferring mutations of BCR-ABL, including gatekeeper mutation T315I, several single mutations associated with TKI resistance, and certain highly resistant compound mutations. Our study provided a deeper understanding of the development of PROTACs targeting BCR-ABL and novel potential therapeutic agents for CML treatment.

HJM-561, a Potent, Selective, and Orally Bioavailable EGFR PROTAC that Overcomes Osimertinib-Resistant EGFR Triple Mutations.

The EGFR C797S mutation is the most common on-target resistance mechanism to osimertinib in patients with advanced non-small cell lung cancer (NSCLC). Currently there are no effective treatment options for patients with NSCLC harboring EGFR C797S triple mutants (Del19/T790M/C797S and L858R/T790M/C797S). Herein, we report an orally bioavailable EGFR PROTAC, HJM-561, which selectively degrades the EGFR C797S-containing triple mutants. HJM-561 potently inhibits the proliferation of Del19/T790M/C797S and L858R/T790M/C797S Ba/F3 cells while sparing cells expressing wild-type EGFR. Oral administration of HJM-561 shows robust antitumor activity in EGFR Del19/T790M/C797S-driven Ba/F3 CDX and PDX models that were resistant to osimertinib treatment. Taken together, our results suggest that HJM-561 is a promising therapeutic option for overcoming EGFR triple mutation-mediated drug resistance in NSCLC.

Simultaneous Measurement of Single-Cell Mechanics and Cell-to-Materials Adhesion Using Fluidic Force Microscopy.

The connection between cells and their substrate is essential for biological processes such as cell migration. Atomic force microscopy nanoindentation has often been adopted to measure single-cell mechanics. Very recently, fluidic force microscopy has been developed to enable rapid measurements of cell adhesion. However, simultaneous characterization of the cell-to-material adhesion and viscoelastic properties of the same cell is challenging. In this study, we present a new approach to simultaneously determine these properties for single cells, using fluidic force microscopy. For MCF-7 cells grown on tissue-culture-treated polystyrene surfaces, we found that the adhesive force and adhesion energy were correlated for each cell. Well-spread cells tended to have stronger adhesion, which may be due to the greater area of the contact between cellular adhesion receptors and the surface. By contrast, the viscoelastic properties of MCF-7 cells cultured on the same surface appeared to have little dependence on cell shape. This methodology provides an integrated approach to better understand the biophysics of multiple cell types.

Discovery of novel BCR-ABL PROTACs based on the cereblon E3 ligase design, synthesis, and biological evaluation.

Protein degradation is a promising strategy for drug development. Proteolysis-targeting chimeras (PROTACs) hijacking the E3 ligase cereblon (CRBN) exhibit enormous potential and universal degradation performance due to the small molecular weight of CRBN ligands. In this study, the CRBN-recruiting PROTACs were explored on the degradation of oncogenic fusion protein BCR-ABL, which drives the pathogenesis of chronic myeloid leukemia (CML). A series of novel PROTACs were synthesized by conjugating BCR-ABL inhibitor dasatinib to the CRBN ligand including pomalidomide and lenalidomide, and the extensive structure-activity relationship (SAR) studies were performed focusing on optimization of linker parameters. Therein, we uncovered that pomalidomide-based degrader 17 (SIAIS056), possessing sulfur-substituted carbon chain linker, exhibits the most potent degradative activity in vitro and favorable pharmacokinetics in vivo. Besides, degrader 17 also degrades a variety of clinically relevant resistance-conferring mutations of BCR-ABL. Furthermore, degrader 17 induces significant tumor regression against K562 xenograft tumors. Our study indicates that 17 as an efficacious BCR-ABL degrader warrants intensive investigation for the future treatment of BCR-ABL+ leukemia.

Discovery of a Brigatinib Degrader SIAIS164018 with Destroying Metastasis-Related Oncoproteins and a Reshuffling Kinome Profile.

Proteolysis-targeting chimera (PROTAC) is an attractive technology in drug discovery. Canonically, targets act as a basic starting point in the most previous PROTAC design. Here, we designed degraders considering from the view of clinical benefits. With this novel design, Brigatinib was turned into a degrader SIAIS164018 and endowed with unique features. First, SIAIS164018 could degrade not only ALK fusion proteins in activating or G1202R-mutated form but also mutant EGFR with L858R + T790M, which are two most important targets in non-small-cell lung cancer. Second, SIAIS164018 strongly inhibited cell migration and invasion of Calu-1 and MDA-MB-231. Third and surprisingly, SIAIS164018 degrades several important oncoproteins involved in metastasis such as FAK, PYK2, and PTK6. Interestingly, SIAIS164018 reshuffled the kinome ranking profile when compared to Brigatinib. Finally, SIAIS164018 is orally bioavailable and well tolerated in vivo. SIAIS164018 is an enlightening degrader for us to excavate the charm of protein degradation.

Development of a Brigatinib degrader (SIAIS117) as a potential treatment for ALK positive cancer resistance.

EML4-ALK and NPM-ALK fusion proteins possess constitutively activated ALK (anaplastic lymphoma kinase) activity, which in turn leads to the development of non-small cell lung cancer and anaplastic large-cell lymphomas (ALCLs). FDA-approved ALK inhibitor drugs cause significant cancer regression. However, drug resistance eventually occurs and it becomes a big obstacle in clinic. Novel proteolysis targeting chimera (PROTAC) technology platform provides a potential therapeutic strategy for drug resistance. Herein, we designed and synthesized a series of ALK PROTACs based on Brigatinib and VHL-1 conjunction, and screened SIAIS117 as the best degrader which not only blocked the growth of SR and H2228 cancer cell lines, but also degraded ALK protein. In addition, SIAIS117 also showed much better growth inhibition effect than Brigatinib on 293T cell line that exogenously expressed G1202R-resistant ALK proteins. Furthermore, it also degraded G1202R mutant ALK protein in vitro. At last, it has the potentially anti-proliferation ability of small cell lung cancer. Thus, we have successfully generated the degrader SIAIS117 that can potentially overcome resistance in cancer targeted therapy.

Discovery of SIAIS178 as an Effective BCR-ABL Degrader by Recruiting Von Hippel-Lindau (VHL) E3 Ubiquitin Ligase.

The oncogenic fusion protein BCR-ABL is the driving force of leukemogenesis in chronic myeloid leukemia (CML). Despite great progress for CML treatment through application of tyrosine kinase inhibitors (TKIs) against BCR-ABL, long-term drug administration and clinical resistance continue to be an issue. Herein, we described the design, synthesis, and evaluation of novel proteolysis-targeting chimeric (PROTAC) small molecules targeting BCR-ABL which connect dasatinib and VHL E3 ubiquitin ligase ligand by extensive optimization of linkers. Our efforts have yielded SIAIS178 (19), which induces proper interaction between BCR-ABL and VHL ligase leading to effective degradation of BCR-ABL protein, achieves significant growth inhibition of BCR-ABL+ leukemic cells in vitro, and induces substantial tumor regression against K562 xenograft tumors in vivo. In addition, SIAIS178 also degrades several clinically relevant resistance-conferring mutations. Our data indicate that SIAIS178 as efficacious BCR-ABL degrader warrants extensive further investigation for the treatment of BCR-ABL+ leukemia.

Regulating, Measuring, and Modeling the Viscoelasticity of Bacterial Biofilms

Biofilms occur in a broad range of environments under heterogeneous physicochemical conditions, such as in bioremediation plants, on surfaces of biomedical implants, and in the lungs of cystic fibrosis patients. In these scenarios, biofilms are subjected to shear forces, but the mechanical integrity of these aggregates often prevents their disruption or dispersal. Biofilms' physical robustness is the result of the multiple biopolymers secreted by constituent microbial cells which are also responsible for numerous biological functions. A better understanding of the role of these biopolymers and their response to dynamic forces is therefore crucial for understanding the interplay between biofilm structure and function. In this paper, we review experimental techniques in rheology, which help quantify the viscoelasticity of biofilms, and modeling approaches from soft matter physics that can assist our understanding of the rheological properties. We describe how these methods could be combined with synthetic biology approaches to control and investigate the effects of secreted polymers on the physical properties of biofilms. We argue that without an integrated approach of the three disciplines, the links between genetics, composition, and interaction of matrix biopolymers and the viscoelastic properties of biofilms will be much harder to uncover.

How cell culture conditions affect the microstructure and nanomechanical properties of extracellular matrix formed by immortalized human mesenchymal stem cells: An experimental and modelling study.

This paper presents an investigation of how different culture media (i.e. basal and osteogenic media) affect the nanomechanical properties and microstructure of the mineralized matrix produced by the human mesenchymal stem cell line Y201, from both an experimental and theoretical approach. A bone nodule (i.e. mineralized matrix) cultured from basal medium shows a more anisotropic microstructure compared to its counterpart cultured from an osteogenic medium. As confirmed by finite element simulations, this anisotropic microstructure explains the bimodal distribution of the corresponding mechanical properties very well. The overall nanomechanical response of the bone nodule from the osteogenic medium is poorer compared to its counterpart from the basal medium. The bone nodules, from both basal and osteogenic media, have shown reverse aging effects in terms of mechanical properties. These are possibly due to the fact that cell proliferation outcompetes the mineralization process.

Preparation and characterization of flexible lithium iron phosphate/graphene/cellulose electrode for lithium ion batteries.

In this work, a free-standing flexible composite electrode was prepared by vacuum filtration method with LiFePO4, graphene and nanofibrillated cellulose (NFC). Compared with the pure LiFePO4 electrode, the resulting flexible composite (LiFePO4/graphene/NFC) electrode showed excellent mechanical flexibility, and possessed an enhanced initial discharge capacity of 151 mA h/g (0.1 C) and a good capacity retention rate with only 5% loss after 60 cycles due to suitable electrolyte wettability at the interface. Furthermore, the NFC and graphene formed a three-dimensional conductive framework, which provided high-speed electron conduction in the composite and reduced electrode polarization during charging-discharging processes. Moreover, the composite electrode could endure bending tests up to 1000 times, highlighting preferable mechanical strength and durability. These results demonstrated that the as-fabricated electrodes could be applied as flexible electrodes with an embedded power supply.

Easily fabricated and lightweight PPy/PDA/AgNW composites for excellent electromagnetic interference shielding.

Conductive polymer composites (CPCs) containing nanoscale conductive fillers have been widely studied for their potential use in various applications. In this paper, polypyrrole (PPy)/polydopamine (PDA)/silver nanowire (AgNW) composites with high electromagnetic interference (EMI) shielding performance, good adhesion ability and light weight are successfully fabricated via a simple in situ polymerization method followed by a mixture process. Benefiting from the intrinsic adhesion properties of PDA, the adhesion ability and mechanical properties of the PPy/PDA/AgNW composites are significantly improved. The incorporation of AgNWs endows the functionalized PPy with tunable electrical conductivity and enhanced EMI shielding effectiveness (SE). By adjusting the AgNW loading degree in the PPy/PDA/AgNW composites from 0 to 50 wt%, the electrical conductivity of the composites greatly increases from 0.01 to 1206.72 S cm-1, and the EMI SE of the composites changes from 6.5 to 48.4 dB accordingly (8.0-12.0 GHz, X-band). Moreover, due to the extremely low density of PPy, the PPy/PDA/AgNW (20 wt%) composites show a superior light weight of 0.28 g cm-3. In general, it can be concluded that the PPy/PDA/AgNW composites with tunable electrical conductivity, good adhesion properties and light weight can be used as excellent EMI shielding materials.

Penetration of blood-brain barrier and antitumor activity and nerve repair in glioma by doxorubicin-loaded monosialoganglioside micelles system.

For the treatment of glioma and other central nervous system diseases, one of the biggest challenges is that most therapeutic drugs cannot be delivered to the brain tumor tissue due to the blood-brain barrier (BBB). The goal of this study was to construct a nanodelivery vehicle system with capabilities to overcome the BBB for central nervous system administration. Doxorubicin as a model drug encapsulated in ganglioside GM1 micelles was able to achieve up to 9.33% loading efficiency and 97.05% encapsulation efficiency by orthogonal experimental design. The in vitro study demonstrated a slow and sustainable drug release in physiological conditions. In the cellular uptake studies, mixed micelles could effectively transport into both human umbilical vein endothelial cells and C6 cells. Furthermore, biodistribution imaging of mice showed that the DiR/GM1 mixed micelles were accumulated sustainably and distributed centrally in the brain. Experiments on zebrafish confirmed that drug-loaded GM1 micelles can overcome the BBB and enter the brain. Among all the treatment groups, the median survival time of C6-bearing rats after administering DOX/GM1 micelles was significantly prolonged. In conclusion, the ganglioside nanomicelles developed in this work can not only penetrate BBB effectively but also repair nerves and kill tumor cells at the same time.

Effects of elemene on inhibiting proliferation of vascular smooth muscle cells and promoting reendothelialization at the stent implantation site.

Anticancer drugs are commonly used as inhibitors of vascular smooth muscle cell (VSMC) proliferation in clinical treatments. This study aims to investigate how elemene affects the proliferation of VSMCs, the restenosis, and the reendothelialization after implanting the elemene-coated stents. VSMCs derived from rat aorta were used to test the cell proliferation, cell cycle, migration, apoptosis, cytoskeletal protein F-actin, intracellular Ca2+, IncRNA chip and gene expression of PCNA, P53, and Cx43 when cultured with elemene. It was found that elemene can inhibit proliferation, induce apoptosis and block the connections between VSMCs in a dose-dependent manner. IncRNA chip analysis has revealed that there was a significant difference in the expression of 1417 genes and 34 signaling pathways. Elemene liposome membranes prepared by electrostatic spray could also inhibit the proliferation of VSMCs. In addition, after implanting the elemene-coated stent into a rabbit iliac artery for 12 weeks, the surface of elemene-coated stents was fully covered with a layer of neointima and a few platelets. However, a large number of platelets aggregated and attached on the uncoated stents (control samples). In conclusion, elemene could inhibit VSMC proliferation in vitro, which involved the regulation of various signal transduction pathways, and elemene-coated stents could promote endothelialization after stent implantation. Thus, elemene has great potential for the clinical treatment of restenosis and reendothelialization.

3D culture of human pluripotent stem cells in RGD-alginate hydrogel improves retinal tissue development.

No treatments exist to effectively treat many retinal diseases. Retinal pigmented epithelium (RPE) and neural retina can be generated from human embryonic stem cells/induced pluripotent stem cells (hESCs/hiPSCs). The efficacy of current protocols is, however, limited. It was hypothesised that generation of laminated neural retina and/or RPE from hiPSCs/hESCs could be enhanced by three dimensional (3D) culture in hydrogels. hiPSC- and hESC-derived embryoid bodies (EBs) were encapsulated in 0.5% RGD-alginate; 1% RGD-alginate; hyaluronic acid (HA) or HA/gelatin hydrogels and maintained until day 45. Compared with controls (no gel), 0.5% RGD-alginate increased: the percentage of EBs with pigmented RPE foci; the percentage EBs with optic vesicles (OVs) and pigmented RPE simultaneously; the area covered by RPE; frequency of RPE cells (CRALBP+); expression of RPE markers (TYR and RPE65) and the retinal ganglion cell marker, MATH5. Furthermore, 0.5% RGD-alginate hydrogel encapsulation did not adversely affect the expression of other neural retina markers (PROX1, CRX, RCVRN, AP2α or VSX2) as determined by qRT-PCR, or the percentage of VSX2 positive cells as determined by flow cytometry. 1% RGD-alginate increased the percentage of EBs with OVs and/or RPE, but did not significantly influence any other measures of retinal differentiation. HA-based hydrogels had no significant effect on retinal tissue development. The results indicated that derivation of retinal tissue from hESCs/hiPSCs can be enhanced by culture in 0.5% RGD-alginate hydrogel. This RGD-alginate scaffold may be useful for derivation, transport and transplantation of neural retina and RPE, and may also enhance formation of other pigmented, neural or epithelial tissue. STATEMENT OF SIGNIFICANCE: The burden of retinal disease is ever growing with the increasing age of the world-wide population. Transplantation of retinal tissue derived from human pluripotent stem cells (PSCs) is considered a promising treatment. However, derivation of retinal tissue from PSCs using defined media is a lengthy process and often variable between different cell lines. This study indicated that alginate hydrogels enhanced retinal tissue development from PSCs, whereas hyaluronic acid-based hydrogels did not. This is the first study to show that 3D culture with a biomaterial scaffold can improve retinal tissue derivation from PSCs. These findings indicate potential for the clinical application of alginate hydrogels for the derivation and subsequent transplantation retinal tissue. This work may also have implications for the derivation of other pigmented, neural or epithelial tissue.