Asymmetric crowders and membrane morphology at the nexus of intracellular trafficking and oncology.

A definitive understanding of the interplay between protein binding/migration and membrane curvature evolution is emerging but needs further study. The mechanisms defining such phenomena are critical to intracellular transport and trafficking of proteins. Among trafficking modalities, exosomes have drawn attention in cancer research as these nano-sized naturally occurring vehicles are implicated in intercellular communication in the tumor microenvironment, suppressing anti-tumor immunity and preparing the metastatic niche for progression. A significant question in the field is how the release and composition of tumor exosomes are regulated. In this perspective article, we explore how physical factors such as geometry and tissue mechanics regulate cell cortical tension to influence exosome production by co-opting the biophysics as well as the signaling dynamics of intracellular trafficking pathways and how these exosomes contribute to the suppression of anti-tumor immunity and promote metastasis. We describe a multiscale modeling approach whose impact goes beyond the fundamental investigation of specific cellular processes toward actual clinical translation. Exosomal mechanisms are critical to developing and approving liquid biopsy technologies, poised to transform future non-invasive, longitudinal profiling of evolving tumors and resistance to cancer therapies to bring us one step closer to the promise of personalized medicine.

A Multidisciplinary Hyper-Modeling Scheme in Personalized In Silico Oncology: Coupling Cell Kinetics with Metabolism, Signaling Networks, and Biomechanics as Plug-In Component Models of a Cancer Digital Twin.

The massive amount of human biological, imaging, and clinical data produced by multiple and diverse sources necessitates integrative modeling approaches able to summarize all this information into answers to specific clinical questions. In this paper, we present a hypermodeling scheme able to combine models of diverse cancer aspects regardless of their underlying method or scale. Describing tissue-scale cancer cell proliferation, biomechanical tumor growth, nutrient transport, genomic-scale aberrant cancer cell metabolism, and cell-signaling pathways that regulate the cellular response to therapy, the hypermodel integrates mutation, miRNA expression, imaging, and clinical data. The constituting hypomodels, as well as their orchestration and links, are described. Two specific cancer types, Wilms tumor (nephroblastoma) and non-small cell lung cancer, are addressed as proof-of-concept study cases. Personalized simulations of the actual anatomy of a patient have been conducted. The hypermodel has also been applied to predict tumor control after radiotherapy and the relationship between tumor proliferative activity and response to neoadjuvant chemotherapy. Our innovative hypermodel holds promise as a digital twin-based clinical decision support system and as the core of future in silico trial platforms, although additional retrospective adaptation and validation are necessary.

Identifying Community Safety and Policy-Based Injury Prevention Opportunities to Reduce Golf Cart Injuries.

BACKGROUND: In small US communities, golf cart utilization has become increasingly more common. In the past 3 years, the incidence and severity of pediatric golf cart-related trauma evaluated at our trauma center has noticeably increased. Thus, the aim of this study was to analyze trends, identify risk and protective factors, and provide community-level recommendations to improve golf cart safety for children in a coastal community. METHODS: A retrospective cross-sectional study of our institutional trauma registry was performed. The registry was queried for golf cart injuries between 2012 -2022. Demographics, accident details, hospital course and outcomes were reviewed. Data analysis involved quantitative statistics. Incident locations were mapped, including additional data from the County emergency medical service. Additionally, customer education at four prominent golf rental shops was observed. RESULTS: Annual golf cart-related traumas doubled starting in 2020. Of 235 total patients, 105 (46%) were children. Median age was 11.5 years (range 2-17). 55% were female and 67% were non-Hispanic White. 80% were out-of-county residents. The most common injury location was extremity (56%). Median ISS was 4, and 3% died. Only 10% of children were restrained. 41% were ejected and most (84%) were front-facing passengers. Ejection was associated with more severe injury (OR 4.13, p = 0.01). Most injuries occurred during 5-10 pm (47%), weekends and summertime. Nighttime injuries were more severe than daytime (p = 0.04). A hotspot of crashes was identified in a zone where golf carts were restricted. Rental stores provided education on seat belt use, car seat use for infants, and off-limit zones. However, rules were not enforced. CONCLUSION: Our results inform the following golf cart injury prevention opportunities: raising awareness of injury risks to children in high-tourist areas, partnering with rental stores to enforce rules, improving signage, adding protected lanes, and adopting a no nighttime operation policy. LEVEL OF EVIDENCE: IV.

Temporal Trends of Neonatal Surgical Conditions in Texas and Accessibility to Pediatric Surgical Care.

INTRODUCTION: Texas consistently accounts for approximately 10% of annual national births, the second highest of all US states. This temporal study aimed to evaluate incidences of neonatal surgical conditions across Texas and to delineate regional pediatric surgeon accessibility. METHODS: The Texas Birth Defects Registry was queried from 1999 to 2018, based on 11 well-established regions. Nine disorders (30,476 patients) were identified as being within the operative scope of pediatric surgeons: biliary atresia (BA), pyloric stenosis (PS), Hirschsprung's disease, stenosis/atresia of large intestine/rectum/anus, stenosis/atresia of small intestine, tracheoesophageal fistula/esophageal atresia, gastroschisis, omphalocele, and congenital diaphragmatic hernia. Annual and regional incidences were compared (/10,000 births). Statewide pediatric surgeons were identified through the American Pediatric Surgical Association directory. Regional incidences of neonatal disorder per surgeon were evaluated from 2010 to 2018 as a surrogate for provider disparity. RESULTS: PS demonstrated the highest incidence (14.405/10,000), while BA had the lowest (0.707/10,000). Overall, incidences of PS and BA decreased significantly, while incidences of Hirschsprung's disease and small intestine increased. Other diagnoses remained stable. Regions 2 (48.24/10,000) and 11 (47.79/10,000) had the highest incidence of neonatal conditions; Region 6 had the lowest (34.68/10,000). Three rural regions (#2, 4, 9) lacked pediatric surgeons from 2010 to 2018. Of regions with at least one surgeon, historically underserved regions (#10, 11) along the Texas-Mexico border consistently had the highest defect per surgeon rates. CONCLUSIONS: There are temporal and regional differences in incidences of neonatal conditions treated by pediatric surgeons across Texas. Improving access to neonatal care is a complex issue that necessitates collaborative efforts between state legislatures, health systems, and providers.

Computational Design of Peptides for Biomaterials Applications.

Computer-aided molecular design and protein engineering emerge as promising and active subjects in bioengineering and biotechnological applications. On one hand, due to the advancing computing power in the past decade, modeling toolkits and force fields have been put to use for accurate multiscale modeling of biomolecules including lipid, protein, carbohydrate, and nucleic acids. On the other hand, machine learning emerges as a revolutionary data analysis tool that promises to leverage physicochemical properties and structural information obtained from modeling in order to build quantitative protein structure-function relationships. We review recent computational works that utilize state-of-the-art computational methods to engineer peptides and proteins for various emerging biomedical, antimicrobial, and antifreeze applications. We also discuss challenges and possible future directions toward developing a roadmap for efficient biomolecular design and engineering.

Quality of Surgical Care Within the Criminal Justice Health Care System.

Importance: Individuals who are incarcerated represent a vulnerable group due to concerns about their ability to provide voluntary and informed consent, and there are considerable legal protections regarding their participation in medical research. Little is known about the quality of surgical care received by this population. Objective: To evaluate perioperative surgical care provided to patients who are incarcerated within the Texas Department of Criminal Justice (TDCJ) and compare their outcomes with that of the general nonincarcerated population. Design, Setting, and Participants: This cohort study analyzed data from patients who were incarcerated within the TDCJ and underwent general or vascular surgery at the University of Texas Medical Branch (UTMB) from 2012 to 2021. Case-specific outcomes for a subset of these patients and for patients in the general academic medical center population were obtained from the American College of Surgeons National Quality Improvement Program (ACS-NSQIP) and compared. Additional quality metrics (mortality index, length of stay index, and excess hospital days) from the Vizient Clinical Data Base were analyzed for patients in the incarcerated and nonincarcerated groups who underwent surgery at UTMB in 2020 and 2021 to provide additional recent data. Patient-specific demographics, including age, sex, and comorbidities were not available for analysis within this data set. Main Outcome and Measures: Perioperative outcomes (30-day morbidity, mortality, and readmission rates) were compared between the incarcerated and nonincarcerated groups using the Fisher exact test. Results: The sample included data from 6675 patients who were incarcerated and underwent general or vascular surgery at UTMB from 2012 to 2021. The ACS-NSQIP included data (2012-2021) for 2304 patients who were incarcerated and 602 patients who were not and showed that outcomes were comparable between the TDCJ population and that of the general population treated at the academic medical center with regard to 30-day readmission (6.60% vs 5.65%) and mortality (0.91% vs 1.16%). However, 30-day morbidity was significantly higher in the TDCJ population (8.25% vs 5.48%, P = .01). The 2020 and 2021 data from the Vizient Clinical Data Base included 629 patients who were incarcerated and 2614 who were not and showed that the incarcerated and nonincarcerated populations did not differ with regard to 30-day readmission (12.52% vs 11.30%) or morbidity (1.91% vs 2.60%). Although the unadjusted mortality rate was significantly lower in the TDCJ population (1.27% vs 2.68%, P = .04), mortality indexes, which account for case mix index, were similar between the 2 populations (1.17 vs 1.12). Conclusions and Relevance: Findings of this cohort study suggest that patients who are incarcerated have equivalent rates of mortality and readmission compared with a general academic medical center population. Future studies that focus on elucidating the potential factors associated with perioperative morbidity and exploring long-term surgical outcomes in the incarcerated population are warranted.

Activating mutations drive human MEK1 kinase using a gear-shifting mechanism.

There is an unmet need to classify cancer-promoting kinase mutations in a mechanistically cognizant way. The challenge is to understand how mutations stabilize different kinase configurations to alter function, and how this influences pathogenic potential of the kinase and its responses to therapeutic inhibitors. This goal is made more challenging by the complexity of the mutational landscape of diseases, and is further compounded by the conformational plasticity of each variant where multiple conformations coexist. We focus here on the human MEK1 kinase, a vital component of the RAS/MAPK pathway in which mutations cause cancers and developmental disorders called RASopathies. We sought to explore how these mutations alter the human MEK1 kinase at atomic resolution by utilizing enhanced sampling simulations and free energy calculations. We computationally mapped the different conformational stabilities of individual mutated systems by delineating the free energy landscapes, and showed how this relates directly to experimentally quantified developmental transformation potentials of the mutations. We conclude that mutations leverage variations in the hydrogen bonding network associated with the conformational plasticity to progressively stabilize the active-like conformational state of the kinase while destabilizing the inactive-like state. The mutations alter residue-level internal molecular correlations by differentially prioritizing different conformational states, delineating the various modes of MEK1 activation reminiscent of a gear-shifting mechanism. We define the molecular basis of conversion of this kinase from its inactive to its active state, connecting structure, dynamics, and function by delineating the energy landscape and conformational plasticity, thus augmenting our understanding of MEK1 regulation.

The Social Media Footprint of Pediatric Surgery Fellowship Programs: Where Do We Stand?

INTRODUCTION: Social media utilization is expanding within graduate medical education and academic surgery. This study aims to quantify the current social media footprint of pediatric surgery (PS) fellowship training programs. METHODS: United States PS fellowship programs from the American Pediatric Surgical Association website and social media accounts on three platforms (Facebook, Instagram, Twitter) were identified. Authors quantified subject matter within public program content and compared PS social media utilization to other surgical training programs. A public Twitter survey was disseminated to evaluate recent PS applicant Twitter use and perceptions about content posted by programs. RESULTS: Of 51 PS fellowship programs, 23 (45.1%) had active Twitter accounts, 2 (3.9%) had active Facebook accounts, and 1 (2.0%) had an active Instagram account. Cumulatively, 5162 organic posts were published across all 26 accounts (90.4% on Twitter). Most commonly posted content included research/conference presentations (31.3%) and faculty accolades (15.1%), while clinical/OR experience (3.6%), gender/ethnic diversity (2.4%) had the least content. Compared to other training programs, PS has lower utilization of Facebook (p < 0.001) and Instagram (p < 0.001), but similar Twitter utilization (p = 0.09). Twenty-four recent applicants responded to the public Twitter survey. Most (62.5%) used Twitter intentionally for recruitment and networking purposes when applying to fellowship. They expressed desire for increased content related to clinical/OR experiences, program ethnic/gender diversity and recruitment information. CONCLUSION: Amongst PS training programs, Twitter is the most commonly utilized platform. Expanding Twitter usage to more programs and posting more varied content may facilitate opportunities for diverse applicant recruitment and serve as a platform to share clinical knowledge, which will ultimately move the needle towards growth and equity. LEVEL OF EVIDENCE: IV.

Circulating tumor DNA reveals mechanisms of lorlatinib resistance in patients with relapsed/refractory ALK-driven neuroblastoma.

Activating point mutations in Anaplastic Lymphoma Kinase (ALK) have positioned ALK as the only mutated oncogene tractable for targeted therapy in neuroblastoma. Cells with these mutations respond to lorlatinib in pre-clinical studies, providing the rationale for a first-in-child Phase 1 trial (NCT03107988) in patients with ALK-driven neuroblastoma. To track evolutionary dynamics and heterogeneity of tumors, and to detect early emergence of lorlatinib resistance, we collected serial circulating tumor DNA samples from patients enrolled on this trial. Here we report the discovery of off-target resistance mutations in 11 patients (27%), predominantly in the RAS-MAPK pathway. We also identify newly acquired secondary compound ALK mutations in 6 (15%) patients, all acquired at disease progression. Functional cellular and biochemical assays and computational studies elucidate lorlatinib resistance mechanisms. Our results establish the clinical utility of serial circulating tumor DNA sampling to track response and progression and to discover acquired resistance mechanisms that can be leveraged to develop therapeutic strategies to overcome lorlatinib resistance.

Predicting General Surgery Match Outcomes Using Standardized Ranking Metrics.

INTRODUCTION: Objective measurements for applicant ranking are becoming increasingly important, not only to help address the growing number of general surgery applicants each year but also to minimize bias and ensure consistency. We assessed if our general surgery applicant scoring system was an effective tool for accurately predicting the results of the resident match. METHODS: A retrospective review of applicant rank lists from 2017 to 2020 was conducted. Applicants were ranked based on the sum of preinterview and interview scores. The preinterview score is an objective metric related to the applicant's academic portfolio. The interview score is a standardized score based on interview performance. We reviewed match results from ranked candidates and categorized them as academic categorical (AC), community categorical (CC), preliminary surgical (PS), nonsurgical specialty (NS), or unmatched (UM) positions. RESULTS: A total of 378 applicants were interviewed. Forty-nine percent matched into AC, 22% into CC, 11% into PS, and 5% into NS positions, while 13% of the interviewees were UM. Applicants who matched into AC positions had significantly higher preinterview and interview scores than applicants in other categories. Applicants who matched into CC positions had significantly higher interview scores than those categorized as UM, but their preinterview scores did not differ significantly from the UM group. Applicants who did not match into a categorical position (PS, NS, or UM) did not have significantly different preinterview or interview scores from one another. CONCLUSIONS: Our standardized scoring system was effective in stratifying which applicants would match into categorical general surgery residency programs.

Stiff matrix induces exosome secretion to promote tumour growth.

Tissue fibrosis and extracellular matrix (ECM) stiffening promote tumour progression. The mechanisms by which ECM regulates its contacting cells have been extensively studied. However, how stiffness influences intercellular communications in the microenvironment for tumour progression remains unknown. Here we report that stiff ECM stimulates the release of exosomes from cancer cells. We delineate a molecular pathway that links stiff ECM to activation of Akt, which in turn promotes GTP loading to Rab8 that drives exosome secretion. We further show that exosomes generated from cells grown on stiff ECM effectively promote tumour growth. Proteomic analysis revealed that the Notch signalling pathway is activated in cells treated with exosomes derived from tumour cells grown on stiff ECM, consistent with our gene expression analysis of liver tissues from patients. Our study reveals a molecular mechanism that regulates exosome secretion and provides insight into how mechanical properties of the ECM control the tumour microenvironment for tumour growth.

Pediatric combined hepatocellular-cholangiocarcinoma (cHCC-CC) with neuroendocrine features: distinguishing genetic alterations detected by chromosomal microarray.

BACKGROUND: Liver tumors exhibiting hepatocellular, cholangiocarcinoma, and neuroendocrine features are extremely rare, with only five cases reported in the literature. CASE PRESENTATION: We present an unusual case of a combined hepatocellular-cholangiocarcinoma (cHCC-CC) with neuroendocrine features in a pediatric patient. A 16-year-old presented with abdominal pain and a 21.0 cm mass in the right hepatic lobe with extension into the left lobe. Histology showed a poorly differentiated tumor with a solid, tubuloglandular, and microcystic architecture. Immunohistochemistry results were negative for hepatic markers, positive for markers of biliary differentiation, and positive for neuroendocrine differentiation. The neoplasm was reviewed at several institutions with differing diagnoses. Single nucleotide polymorphism (SNP) chromosomal microarray (CMA) showed large deletions within chromosomes 6q and 13q in both the hepatocellular-like areas and the cholangiocarcinoma-like areas, with additional large deletions in the cholangiocarcinoma-like areas, supporting origin from hepatocellular carcinoma. The final diagnosis was a cHCC-CC with neuroendocrine features. CONCLUSIONS: Diagnosis of cHCC-CCs relies predominately on histomorphology, as per the 2018 International Consensus Group on the nomenclature of cHCC-CC. These findings in this case support that the pathological classification of these lesions be based on molecular data, which could better direct treatment. Further classification of cHCC-CCs and determination of their clinicopathological relevance will require more interobserver consistency and continued molecular profiling of these lesions.

PARP1 Inhibition and Effect on Burn Injury-Induced Inflammatory Response and Cardiac Function.

BACKGROUND: Burn injury induces multiple signaling pathways leading to a significant inflammatory storm that adversely affects multiple organs, including the heart. Poly (ADP-ribose) polymerase inhibitor 1 (PARP1) inhibition, with specific agents such as N-(5,6-Dihydro-6-oxo-2-phenanthridinyl)-2-acetamide (PJ34), is effective in reducing oxidative stress and cytokine expression in the heart. We hypothesized that PARP1 inhibition would reduce inflammatory signaling and protect against burn injury-induced cardiac dysfunction. STUDY DESIGN: Male Sprague-Dawley rats (8 weeks old, 300 to 350 g) were randomly assigned to sham injury (Sham), 60% total body surface area burn (24 hours post burn), or 60% total body surface area burn with intraperitoneal administration of PJ34 (20 mg/kg, 24 hours post burn + PJ34) and sacrificed 24 hours after injury. Cardiac function was determined using Vevo 2100 echocardiography. Genetic expression of 84 specific toll-like receptor-mediated signal transduction and innate immunity genes were examined using microarray to evaluate cardiac tissue. Qiagen GeneGlobe Data Analysis Center was used to analyze expression, and genetic clustering was performed using TreeView V2.0.8 software. Real-time quantitative polymerase chain reaction was used to validate identified differentially expressed genes. RESULTS: Burn injury significantly altered multiple genes in the toll-like receptor signaling, interleukin-17 signaling, tumor necrosis factor signaling, and nuclear factor-κB signaling pathways and led to significant cardiac dysfunction. PARP1 inhibition with PJ34 normalized these signaling pathways to sham levels as well as improved cardiac function to sham levels. CONCLUSIONS: PARP1 inhibition normalizes multiple inflammatory pathways that are altered after burn injury and improves cardiac dysfunction. PARP1 pathway inhibition may provide a novel methodology to normalize multiple burn injury-induced inflammatory pathways in the heart.

Extracorporeal Membrane Oxygenation for Adult Patients With Neoplasms: Outcomes and Trend Over the Last 2 Decades.

Extracorporeal membrane oxygenation (ECMO) is utilized in the management of severe respiratory and circulatory failure. Advanced malignancy is a relative contraindication, but the indication for ECMO in the oncologic population has not been clearly established because of the wide spectrum of malignant disease and prognoses. The Extracorporeal Life Support Organization database was queried for patients older than 18 years with an International Classification of Diseases code of neoplasm over the past 2 decades (2000-2019). The data were divided into 2 decades to analyze and compare the trends with background and outcomes. One thousand six-hundred ninety-seven patients met inclusion criteria from the latest decade which is over 15 times the previous decade (n = 110). Compared with the previous decade, ECMO was used more in patients with older age (56 vs . 50.5 years old; p < 0.001), cardiac and extracorporeal cardiopulmonary resuscitation (ECPR) support type ( p = 0.011), and lower oxygenation index (23.0 vs . 35.6; p < 0.001) in the latest decade. Although overall survival did not show significant improvement overall (38.9% vs . 33.6%; p = 0.312), survival in pulmonary ECMO has significantly improved in the latest decade (41.6% vs . 29.1%; p = 0.032). Compared with the previously reported data for all adult ECMO, our patients had a significantly lower survival with pulmonary (41.6% vs . 61.1%; p < 0.001) and cardiac (38.4% vs . 44.3%; p = 0.008) support while not with ECPR.

Prevalence and Impact of Infection during Extracorporeal Membrane Oxygenation in Oncologic Patients: A Retrospective Analysis of the Extracorporeal Life Support Organization (ELSO) Registry.

Background: Extracorporeal membrane oxygenation (ECMO) is widely utilized for severe cardiopulmonary insufficiency, but its application to the oncologic population has been debated given concern for increased risk of infection. This study aims to analyze the implications of infections acquired during ECMO runs in patients with malignancy. Methods: The Extracorporeal Life Support Organization (ELSO) database was queried for patients with an International Classification of Diseases code of neoplasms over the last two decades (2000-2019). Culture-proven infections during ECMO runs were analyzed and compared to previously reported data for all ECMO runs. Results: Two thousand, seven hundred and fifty-seven patients met inclusion criteria. Infection acquired during ECMO run was found in 687 patients, a significantly greater proportion compared to all ECMO runs (24.9% vs 11.7%; P = .001). Adult patients had a significantly higher rate of infection (27.0%; P < .001) compared to neonatal (11.0%) and pediatric (21.4%) patients. Prevalence of infection was highest in pulmonary ECMO (29.0%), while the infection rate standardized with ECMO duration was highest in extracorporeal cardiopulmonary resuscitation (55.03/1000-day ECMO run). Compared with ECMO for all diagnoses, the prevalence of Candida and Klebsiella infection was significantly higher in adult and pediatric oncologic patients. Regardless of the pathogen, the presence of infection was not associated with lower survival (38.6% vs 40.0%; P = .522). Conclusions: Oncologic patients had a significantly higher infection rate while on ECMO compared with the general ECMO population. However, the prognostic impact of these infections was minimal, thus ECMO should not be withheld in oncologic patients solely with concern for infection.

Primary Hepatic Mesothelial Cyst: A Rare Entity to Be Considered in the Differential Diagnosis of Neonatal Cystic Lesions.

We report two cases of primary hepatic mesothelial cysts in neonates previously identified during perinatal imaging. Both neonatal cases were reimaged in the postnatal period, demonstrating the persistence of these cystic hepatic lesions. In both instances, the decision was made to treat with surgical resection and both patients tolerated the surgery well with no significant postoperative complications. Histopathological examination of these lesions discovered a cuboidal lining that was calretinin and WT1 positive and CD31 negative, indicating the diagnosis of a mesothelial cyst of hepatic origin. These cases bring attention to the broad differential diagnosis of congenital primary hepatic cystic lesions, as well as the diagnostic pathway to confirm a primary hepatic mesothelial cyst.

ECM dimensionality tunes actin tension to modulate endoplasmic reticulum function and spheroid phenotypes of mammary epithelial cells.

Patient-derived organoids and cellular spheroids recapitulate tissue physiology with remarkable fidelity. We investigated how engagement with a reconstituted basement membrane in three dimensions (3D) supports the polarized, stress resilient tissue phenotype of mammary epithelial spheroids. Cells interacting with reconstituted basement membrane in 3D had reduced levels of total and actin-associated filamin and decreased cortical actin tension that increased plasma membrane protrusions to promote negative plasma membrane curvature and plasma membrane protein associations linked to protein secretion. By contrast, cells engaging a reconstituted basement membrane in 2D had high cortical actin tension that forced filamin unfolding and endoplasmic reticulum (ER) associations. Enhanced filamin-ER interactions increased levels of PKR-like ER kinase effectors and ER-plasma membrane contact sites that compromised calcium homeostasis and diminished cell viability. Consequently, cells with decreased cortical actin tension had reduced ER stress and survived better. Consistently, cortical actin tension in cellular spheroids regulated polarized basement membrane membrane deposition and sensitivity to exogenous stress. The findings implicate cortical actin tension-mediated filamin unfolding in ER function and underscore the importance of tissue mechanics in organoid homeostasis.

Data driven and biophysical insights into the regulation of trafficking vesicles by extracellular matrix stiffness.

Biomechanical signals from remodeled extracellular matrix (ECM) promote tumor progression. Here, we show that cell-matrix and cell-cell communication may be inherently linked and tuned through mechanisms of mechanosensitive biogenesis of trafficking vesicles. Pan-cancer analysis of cancer cells' mechanical properties (focusing primarily on cell stiffness) on substrates of varied stiffness and composition elucidated a heterogeneous cellular response to mechanical stimuli. Through machine learning, we identified a fingerprint of cytoskeleton-related proteins that accurately characterize cell stiffness in different ECM conditions. Expression of their respective genes correlates with patient prognosis across different tumor types. The levels of selected cytoskeleton proteins indicated that cortical tension mirrors the increase (or decrease) in cell stiffness with a change in ECM stiffness. A mechanistic biophysical model shows that the tendency for curvature generation by curvature-inducing proteins has an ultrasensitive dependence on cortical tension. This study thus highlights the effect of ECM stiffness, mediated by cortical tension, in modulating vesicle biogenesis.

Crowding-induced membrane remodeling: Interplay of membrane tension, polymer density, architecture.

The plasma membrane hosts a wide range of biomolecules, mainly proteins and carbohydrates, that mediate cellular interactions with its environment. The crowding of such biomolecules regulates cellular morphologies and cellular trafficking. Recent discoveries have shown that the structure and density of cell surface polymers and hence the signaling machinery change with the state of the cell, especially in cancer progression. The alterations in membrane-attached glycocalyx and glycosylation of proteins and lipids are common features of cancer cells. The overexpression of glycocalyx polymers, such as mucin and hyaluronan, strongly correlates with cancer metastasis. Here, we present a mesoscale biophysics-based model that accounts for the shape regulation of membranes by crowding of membrane-attached biopolymer-glycocalyx and actin networks. Our computational model is based on the dynamically triangulated Monte Carlo model for membranes and coarse-grained representations of polymer chains. The model allows us to investigate the crowding-induced shape transformations in cell membranes in a tension- and graft polymer density-dependent manner. Our results show that the number of membrane protrusions and their shape depend on membrane tension, with higher membrane tension inducing more tubular protrusions than the vesicular shapes formed at low tension at high surface coverage of polymers. The shape transformations occur above the threshold density predicted by the polymer brush theory, but this threshold also depends on the membrane tension. Increasing the size of the polymer, either by changing the length or by adding side chains, is shown to increase the crowding-induced curvature. The effect of crowding is more prominent for flexible polymers than for semiflexible rigid polymers. We also present an extension of the model that incorporates properties of the actin-like filament networks and demonstrate how tubular structures can be generated by biopolymer crowding on the cytosolic side of cell membranes.