Nexus of signaling and endocytosis in oncogenesis driven by non-small cell lung cancer-associated epidermal growth factor receptor mutants

Epidermal growth factor receptor(EGFR) controls a wide range of cellular processes, and aberrant EGFR signaling as a result of receptor overexpression and/or mutation occurs in many types of cancer. Tumor cells in non-small cell lung cancer(NSCLC) patients that harbor EGFR kinase domain mutations exhibit oncogene addiction to mutant EGFR, which confers high sensitivity to tyrosine kinase inhibitors(TKIs). As patients invariably develop resistance to TKIs, it is important to delineate the cell biological basis of mutant EGFR-induced cellular transformation since components of these pathways can serve as alternate therapeutic targets to preempt or overcome resistance. NSCLC-associated EGFR mutants are constitutively-active and induce ligandindependent transformation in nonmalignant cell lines. Emerging data suggest that a number of factors are critical for the mutant EGFR-dependent tumorigenicity, and bypassing the effects of TKIs on these pathways promotes drug resistance. For example, activation of downstream pathways such as Akt, Erk, STAT3 and Src is critical for mutant EGFR-mediated biological processes. It is now well-established that the potency and spatiotemporal features of cellular signaling by receptor tyrosine kinases such as EGFR, as well as the specific pathways activated, is determined by the nature of endocytic traffic pathways through which the active receptors traverse. Recent evidence indicates that NSCLCassociated mutant EGFRs exhibit altered endocytic trafficking and they exhibit reduced Cbl ubiquitin ligasemediated lysosomal downregulation. More recent work has shown that mutant EGFRs undergo ligand-independent traffic into the endocytic recycling compartment, a behavior that plays a key role in Src pathway activation and oncogenesis. These studies are beginning to delineate the close nexus between signaling and endocytic traffic of EGFR mutants as a key driver of oncogenicprocesses. Therefore, in this review, we will discuss the links between mutant EGFR signaling and endocytic properties, and introduce potential mechanisms by which altered endocytic properties of mutant EGFRs may alter signaling and vice versa as well as their implications for NSCLC therapy.

Determination of diffusion coefficient by image-based fluorescence recovery after photobleaching and single particle tracking system implemented in a single platform

Fluorescence recovery after photobleaching(FRAP)and single particle tracking(SPT)techni-ques determine the diffusion coefficient from average diffusive motion of high-concentration molecules and from trajectories of low-concentration single molecules,respectively.Lateral dif-fusion coefficients measured by FRAP and SPT techniques for the same biomolecule on cell membrane have exhibited inconsistent values across laboratories and platforms with larger dif-fusion coefficient determined by FRAP,but the sources of the inconsistency have not been investigated thoroughly.Here,we designed an image-based FRAP-SPT system and made a direct comparison between FRAP and SPT for diffusion coefficient of submicron particles with known theoretical values derived from Stokes-Einstein equation in aqueous solution.The combined iFRAP-SPT technique allowed us to measure the diffusion coefficient of the same fluorescent particle by utilizing both techniques in a single platform and to scrutinize inherent errors and artifacts of FRAP.Our results reveal that diffusion coefficient overestimated by FRAP is caused by inaccurate estimation of the bleaching spot size and can be corrected by simple image analysis.Our iFRAP-SPT technique can be potentially used for not only cellular membrane dynamics but also for quantitative analysis of the spatiotemporal distribution of the solutes in small scale analytical devices.

Therapeutic implications of SARS-CoV-2 dysregulation of the gutbrain-lung axis

The emergence and rapid spread of novel severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has caused over 180 million confirmed cases resulting in over 4 million deaths worldwide with no clear end in sight for the coronavirus disease 19(COVID-19)pandemic.Most SARS-CoV-2 exposed individuals experience mild to moderate symptoms,including fever,cough,fatigue,and loss of smell and taste.However,many individuals develop pneumonia,acute respiratory distress syndrome,septic shock,and multiorgan dysfunction.In addition to these primarily respiratory symptoms,SARS-CoV-2 can also infiltrate the central nervous system,which may damage the blood-brain barrier and the neuron's synapses.Resultant inflammation and neurodegeneration in the brain stem can further prevent efferent signaling to cranial nerves,leading to the loss of anti-inflammatory signaling and normal respiratory and gastrointestinal functions.Additionally,SARS-CoV-2 can infect enterocytes resulting in gut damage followed by microbial dysbiosis and translocation of bacteria and their byproducts across the damaged epithelial barrier.As a result,this exacerbates pro-inflammatory responses both locally and systemically,resulting in impaired clinical outcomes.Recent evidence has highlighted the complex interactions that mutually modulate respiratory,neurological,and gastrointestinal function.In this review,we discuss the ways SARS-CoV-2 potentially disrupts the gut-brain-lung axis.We further highlight targeting specific responses to SARS-CoV-2 for the development of novel,urgently needed therapeutic interventions.Finally,we propose a prospective related to the individuals from Low-and Middle-Income countries.Here,the underlying propensity for heightened gut damage/microbial translocation is likely to result in worse clinical outcomes during this COVID-19 pandemic.

Polycomb response element-binding sites in the MDR of CLL: Potential tumor suppressor regulation

Chronic lymphocytic leukemia [CLL] is the most common adult leukemia and is heterogeneous in clinical presentation. CLL cases present with various chromosomal aberrations, including 11q23, 14q32, 17p, and trisomy 12, with the most common abnormality being deletion of 13q14 [1]. Although monoallelic deletion of 13q14 is common, there is a subset of patients who have complete nullisomy at 13q14, a locus that has been hypothesized to contribute to CLL pa thogenesis [2] due to loss of tumor suppressors [DLEU and miR-15a/16-1]. We hypothesized that deletion of both copies of 13q14 would lead to uncontrollable proliferation of CLL cells and a poor prognosis. We examined our 13q14 nullisomy for survival, treatment-free survival, lymphocyte doubling time, and the presence of lymphadenopathy. Furthermore, we compared the gene expression profiles between patients with 13q14 monosomy, nullisomy, or normal karyotype. Our results suggest that patients with 13q nullisomy have a higher incidence of bulky lymphadenopathy [16.6% compared to 10% of monosomy patients], a higher frequency of lymphocyte doubling time [27.7% compared to 7.4% of monosomy patients], and a higher rate of needing treatment [50% compared to 18.5% of monosomy patients]. We observed deletion of DLEU1 and HTR2A, consistent with a gene dosage effect, and observed PRE-binding sites on DLEU1. Patients with homozygous deletion of 13q14 had a worse prognosis compared to heterozygotes. Lastly, the DLEU1 locus is a possible “second hit” loss for CLL progression.

Glutamate in cancers:from metabolism to signaling

Glutamine and glutamate are major bioenergy substrates for normal and cancer cell growth.Cancer cells need more biofuel than normal tissues for energy supply,anti-oxidation activity and biomass production.Genes related to metabolic chains in many cancers are somehow mutated,which makes cancer cells more glutamate dependent.Meanwhile,glutamate is an excitatory neurotransmitter for conducting signals through binding with different types of receptors in central neuron system.Interestingly,increasing evidences have shown involvement of glutamate signaling,guided through their receptors,in human malignancy.Dysregulation of glutamate transporters,such as excitatory amino acid transporter and cystine/glutamate antiporter system,also generates excessive extracellular glutamate,which in turn,activates glutamate receptors on cancer cells and results in malignant growth.These features make glutamate an attractive target for anti-cancer drug development with some glutamate targeted but blood brain barrier impermeable anti-psychosis drugs under consideration.We discussed the relevant progressions and drawbacks in this field herein.

The inositol metabolism pathway as a target for neuroprotective strategies

Neurodegeneration is characterized by the progressive and permanent loss of neurons.Degeneration typically results in a debilitating loss of function in an otherwise healthy person.Neurodegenerative diseases have enormous direct health care costs,with some estimates for diseases.

3D printing of multilayered scaffolds for rotator cuff tendon regeneration

Repairing massive rotator cuff tendon defects remains a challenge due to the high retear rate after surgical intervention.3D printing has emerged as a promising technique that enables the fabrication of engineered tissues with heterogeneous structures and mechanical properties,as well as controllable microenvironments for tendon regeneration.In this study,we developed a new strategy for rotator cuff tendon repair by combining a 3D printed scaffold of polylactic-co-glycolic acid(PLGA)with cell-laden collagen-fibrin hydrogels.We designed and fabricated two types of scaffolds:one featuring a separate layer-by-layer structure and another with a tri-layered structure as a whole.Uniaxial tensile tests showed that both types of scaffolds had improved mechanical properties compared to single-layered PLGA scaffolds.The printed scaffold with collagen-fibrin hydrogels effectively supported the growth,proliferation,and tenogenic differentiation of human adipose-derived mesenchymal stem cells.Subcutaneous implantation of the multilayered scaffolds demonstrated their excellent in vivo biocompatibility.This study demonstrates the feasibility of 3D printing multilayered scaffolds for application in rotator cuff tendon regeneration.

Bioengineering strategies for the treatment of peripheral arterial disease

Peripheral arterial disease(PAD)is a progressive atherosclerotic disorder characterized by narrowing and occlusion of arteries supplying the lower extremities.Approximately 200 million people worldwide are affected by PAD.The current standard of operative care is open or endovascular revascularization in which blood flow restoration is the goal.However,many patients are not appropriate candidates for these treatments and are subject to continuous ischemia of their lower limbs.Current research in the therapy of PAD involves developing modalities that induce angiogenesis,but the results of simple cell transplantation or growth factor delivery have been found to be relatively poor mainly due to difficulties in stem cell retention and survival and rapid diffusion and enzymolysis of growth factors following injection of these agents in the affected tissues.Biomaterials,including hydrogels,have the capability to protect stem cells during injection and to support cell survival.Hydrogels can also provide a sustained release of growth factors at the injection site.This review will focus on biomaterial systems currently being investigated as carriers for cell and growth factor delivery,and will also discuss biomaterials as a potential stand-alone method for the treatment of PAD.Finally,the challenges of development and use of biomaterials systems for PAD treatment will be reviewed.