195 research outputs found
Cell-based, computational modeling of mechanical cell-matrix interactions during embryonic development
No full textDuring embryonic development, the behavior of individual cells must be coordinated to create the large scale patterns and tissue movements that shape the whole embryo. Apart from chemical signaling, it has recently become clear that mechanical cell-cell communication is equally important in the coordination of such collective cell behavior. To get a better understanding of mechanical cell-cell communication, we are developing computational models of cells and the extracellular matrix (ECM) - the hard or jelly materials (e.g. collagens, fibronectin) that form the micro-environment of many cells. The models are detailed enough for explaining the response of individual cells to the mechanical properties of the ECM, and sufficiently coarse-grained so as to allow for efficient computational upscaling to the tissue level and beyond. Our model is based on a novel, hybrid Cellular Potts and finite element computational framework. It describes the contractile forces that cells exert on the ECM, the resulting strain fields in the ECM, and the cellular response to local strains. The model simulations reproduce the behavior of individual endothelial cells on compliant matrices, and show that local cell-ECM interactions suffice for explaining interactions of endothelial cell pairs and collective cell behavior, including the formation of cellular networks and sprouting from spheroids [1]. If an external strain is exerted on the ECM, the cells rapidly align with the strain fields, even in response to very subtle strain cues [2]. These initial models relied on phenomenological descriptions of the interactions between cellular protrusions and the ECM. Recently, detailed measurements and new mathematical models of the kinetics of individual focal adhesions (the macromolecular assemblies responsible for mechanical cell-ECM interactions) have become available. In our ongoing work we have include kinetic descriptions of focal adhesions in our models. We will sketch how this approach will allow us to mechanistically predict changes in cell shape and in collective cell behavior from changes in focal adhesion kinetics. Altogether, our models suggest simple mechanisms by which local, mechanical cell-ECM interactions can assist in integrating morphological information in embryos across organizational levels.
[1] R. F. M. van Oers, E. G. Rens, D. J. LaValley, C. A. Reinhart-King, and R. M. H. Merks, “Mechanical Cell-Matrix Feedback Explains Pairwise and Collective Endothelial Cell Behavior In Vitro,” PLoS Comput. Biol., vol. 10, no. 8, p. e1003774, Aug. 2014.
[2] E. G. Rens and R. M. H. Merks, “Cell Contractility Facilitates Alignment of Cells and Tissues to Static Uniaxial Stretch,” Biophysical Journal, vol. 112, no. 4, pp. 755–766, Feb. 2017.Non UBCUnreviewedAuthor affiliation: CWI and Leiden UniversityFacult
Congenital rhabdomyosarcoma: A report from the European paediatric Soft tissue sarcoma Study Group
No full textProcedure: Congenital rhabdomyosarcoma (RMS) represents a challenging disease due to its characteristics and the difficulties in delivering treatment in this immature population. Methods: We analyzed treatment and outcome of patients with congenital RMS, defined as tumor diagnosed in the first 2 months of life, enrolled in the European paediatric Soft tissue sarcoma Study Group protocols. Results: Twenty-four patients with congenital RMS were registered. All, except one patient (PAX3-FOXO1-positive metastatic RMS), had favorable histology and localized disease. Three patients had VGLL2-CITED2/NCOA2 fusion. Complete tumor resection was achieved in 10 patients. No radiotherapy was given. Chemotherapy doses were adjusted to age and weight. Only two patients required further dose reduction for toxicity. The 5-year event-free survival (EFS) and overall survival (OS) were 75.0% (95% confidence interval [CI] 52.6–87.9) and 87.3% (95% CI 65.6–95.7), respectively. Progressive disease was the main cause of treatment failure. Conclusion: Patients with congenital RMS presented with a favorable disease, allowing weight- and age-adjusted doses of chemotherapy and avoidance of irradiation, without compromising the outcome
Fluctuations in auxin levels depend upon synchronicity of cell divisions in a one-dimensional model of auxin transport
No full textAuxin is a well-studied plant hormone, the spatial distribution of which remains incompletely understood. Here, we investigate the effects of cell growth and divisions on the dynamics of auxin patterning, using a combination of mathematical modelling and experimental observations. In contrast to most prior work, models are not designed or tuned with the aim to produce a specific auxin pattern. Instead, we use well-established techniques from dynamical systems theory to uncover and classify ranges of auxin patterns as exhaustively as possible as parameters are varied. Previous work using these techniques has shown how a multitude of stable auxin patterns may coexist, each attainable from a specific ensemble of initial conditions. When a key parameter spans a range of values, these steady patterns form a geometric curve with successive folds, often nicknamed a snaking diagram. As we introduce growth and cell division into a one-dimensional model of auxin distribution, we observe new behaviour which can be explained in terms of this diagram. Cell growth changes the shape of the snaking diagram, and this corresponds in turn to deformations in the patterns of auxin distribution. As divisions occur this can lead to abrupt creation or annihilation of auxin peaks. We term this phenomenon ‘snake-jumping’. Under rhythmic cell divisions, we show how this can lead to stable oscillations of auxin. We also show that this requires a high level of synchronisation between cell divisions. Using 18 hour time-lapse imaging of the auxin reporter DII:Venus in roots of Arabidopsis thaliana, we show auxin fluctuates greatly, both in terms of amplitude and periodicity, consistent with the snake-jumping events observed with non-synchronised cell divisions. Periodic signals downstream of the auxin signalling pathway have previously been recorded in plant roots. The present work shows that auxin alone is unlikely to play the role of a pacemaker in this context
Patients with completely resected nongenitourinary low-risk embryonal RMS are candidates for reduced duration low-intensity chemotherapy
No full textBackground: The survival of patients with localized embryonal rhabdomyosarcoma (RMS) completely resected at diagnosis is greater than 90%. Most patients have paratesticular, uterine, or vaginal RMS, limiting specific analyses of RMS localized in other anatomic regions. This international study was conducted to define the outcome for completely resected embryonal RMS at sites other than paratesticular, uterine, or vaginal primary sites. Methods: A total of 113 patients aged 0–18 years were identified who were enrolled from January 1995 to December 2016 in Children's Oncology Group (COG) (64 patients) and European protocols (49). Genitourinary nonbladder and prostate RMS were excluded. The recommended chemotherapy was vincristine and actinomycin-D (VA) for 24 weeks or ifosfamide plus VA in the European protocols and VA for 48 weeks or VA plus cyclophosphamide in the COG protocols. Results: The most common primary sites were nonparameningeal head and neck (40.7%), other (23.9%), and extremities (20.4%). In the COG studies, 42% of patients received VA and 58% VA plus cyclophosphamide. In Europe, 53% received VA and 47% ifosfamide plus VA. With a median follow-up of 97.5 months, the 5-year progression-free and overall survival was 80.0% (71.2%–86.4%) and 92.5% (85.6%–96.2%), respectively, without significant differences between chemotherapy regimens. Tumor size (5 cm) significantly influenced overall survival: 96.2% (88.6%–98.8%) vs. 80.6% (59.5%–91.4%), respectively (p =.01). Conclusions: Survival of patients with nonalveolar RMS completely resected at diagnosis is excellent among tumors arising from nonparatesticular, uterine, and vaginal sites, and patients may be treated successfully with low-intensity chemotherapy. To reduce the burden of treatment, VA for 24 weeks may be considered in children with tumors <5 cm
Outcome of patients with undifferentiated embryonal sarcoma of the liver treated according to European soft tissue sarcoma protocols
No full textBackgroundTo assess the outcomes of pediatric patients with undifferentiated embryonal sarcoma of the liver (UESL) and treatment including at least surgery and systemic chemotherapy. MethodsThis study included patients aged up to 21 years with a pathological diagnosis of UESL prospectively enrolled from 1995 to 2016 in three European trials focusing on the effects of surgical margins, preoperative chemotherapy, use of radiotherapy (RT), and chemotherapy. ResultsOut of 65 patients with a median age at diagnosis of 8.7 years (0.6-20.8), 15 had T2 tumors, and one had lymph node spread, 14 were Intergroup Rhabdomyosarcoma Study (IRS) I, nine IRS II, 38 IRS III, and four IRS IV. Twenty-eight upfront surgeries resulted in five operative spillages and 11 infiltrated surgical margins, whereas 37 delayed surgeries resulted in no spillages (p = .0119) and three infiltrated margins (p = .0238). All patients received chemotherapy, including anthracyclines in 47. RT was administered in 15 patients. With a median follow-up of 78.6 months, 5-year overall and event-free survivals (EFS) were 90.1% (95% confidence interval [CI]: 79.2-95.5) and 89.1% (95% CI: 78.4-94.6), respectively. Two out four local relapses had previous infiltrated margins and two out of three patients with metastatic relapses received reduced doses of alkylating agents. Infiltrated margins (p = .1607), T2 stage (p = .3870), use of RT (p = .8731), and anthracycline-based chemotherapy (p = .1181) were not correlated with EFS. ConclusionsMultimodal therapy improved the outcome of UESL. Neoadjuvant chemotherapy for pediatric patients increases the probability of complete surgical resection. The role of anthracyclines and RT for localized disease remains unclear
Biological Role and Clinical Implications of MYOD1L122R Mutation in Rhabdomyosarcoma
No full textMajor progress in recent decades has furthered our clinical and biological understanding of rhabdomyosarcoma (RMS) with improved stratification for treatment based on risk factors. Clinical risk factors alone were used to stratify patients for treatment in the European Pediatric Soft Tissue Sarcoma Study Group (EpSSG) RMS 2005 protocol. The current EpSSG overarching study for children and adults with frontline and relapsed rhabdomyosarcoma (FaR-RMS NCT04625907) includes FOXO1 fusion gene status in place of histology as a risk factor. Additional molecular features of significance have recently been recognized, including the MYOD1L122R gene mutation. Here, we review biological information showing that MYOD1L122R blocks cell differentiation and has a MYC-like activity that enhances tumorigenesis and is linked to an aggressive cellular phenotype. MYOD1L122R mutations can be found together with mutations in other genes, such as PIK3CA, as potentially cooperating events. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, ten publications in the clinical literature involving 72 cases were reviewed. MYOD1L122R mutation in RMS can occur in both adults and children and is frequent in sclerosing/spindle cell histology, although it is also significantly reported in a subset of embryonal RMS. MYOD1L122R mutated tumors most frequently arise in the head and neck and extremities and are associated with poor outcome, raising the issue of how to use MYOD1L122R in risk stratification and how to treat these patients most effectively
Adolescents and young adults with rhabdomyosarcoma treated in the European paediatric Soft tissue sarcoma Study Group (EpSSG) protocols: a cohort study
No full textBackground: Adolescent and young adult patients with rhabdomyosarcoma often have poorer outcomes than do children. We aimed to compare the findings of adolescent and young adult patients with children enrolled in two prospective clinical protocols. Methods: This retrospective observational analysis was based on data from the European paediatric Soft tissue sarcoma Study Group (EpSSG) rhabdomyosarcoma 2005 trial (phase 3 randomised trial for localised rhabdomyosarcoma, open from April, 2006, to December, 2016) and the EpSSG MTS 2008 protocol (prospective, observational, single-arm study for metastatic rhabdomyosarcoma, open from June, 2010, to December, 2016), which involved 108 centres from 14 different countries in total. For this analysis, patients were categorised according to their age into children (age 0–14 years) and adolescents and young adults (age 15–21 years). For the analysis of adherence to treatment and toxicity, only patients with high-risk localised rhabdomyosarcoma inc..
Therapy and prognostic significance of regional lymph node involvement in embryonal rhabdomyosarcoma: a report from the European paediatric Soft tissue sarcoma Study Group
No full textPurpose: Regional lymph node disease (N1) is a component of the risk-based treatment stratification in rhabdomyosarcoma (RMS). The purpose of this study was to determine the contribution of nodal disease to the prognosis of patients with non-metastatic embryonal RMS (ERMS) and analyse their outcome by treatment received. Patients and methods: Between 2005 and 2016, 1294 children with ERMS were enrolled in the European paediatric Soft tissue sarcoma Study Group (EpSSG) RMS 2005 protocol, 143 patients with N1. Treatment comprised 9 cycles of ifosfamide, vincristine and dactinomycin. Some patients also received doxorubicin and/or maintenance if enrolled in the randomised studies. Local treatment was planned after 4 cycles of chemotherapy and included surgery to remove macroscopic residual tumour and/or radiotherapy (primary tumour and involved nodes). Results: N1 patients were older and presented with tumours of unfavourable size, invasiveness, site and resectability. Unlike alveolar RMS, nodal involvement was more frequent in the head and neck area and rare in extremity sites. The 5-year event-free and overall survival were 75.5% and 86.3% for patients with N0, and 65.2% and 70.7% for patients with N1, respectively. The nodal involvement and the result of surgery at diagnosis (Intergroup Rhabdomyosarcoma Study group) were independent prognostic factors on multivariate analysis. Considering only patients with N1 ERMS, we were not able to identify any treatment variables which correlated with the outcome. Conclusion: In the case of nodal involvement, patients with ERMS present different characteristics and a better outcome than alveolar RMS. Regional nodal involvement is an independent prognostic factor in ERMS, therefore it is appropriate to include this population in the high-risk category
Outcomes of metastatic non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) treated within the BERNIE study: a randomised, phase II study evaluating the addition of bevacizumab to chemotherapy
No full textPurpose: We analysed the cohort of paediatric patients with metastatic non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) treated in the BERNIE protocol, i.e. open-label, multicentre, randomised phase II study evaluating the role of bevacizumab (BO20924/ITCC-006; ClinicalTrials.gov: NCT00643565). Methods: Eligible patients were randomised 1:1 to add or not add bevacizumab to nine courses of intensive multi-drug chemotherapy, followed by 12-month maintenance chemotherapy (plus surgery and radiotherapy). The primary end-point was event-free survival (EFS); secondary objectives were objective response rate (ORR) and overall survival (OS). Results: From 2008 and 2013, 49 NRSTS patients (out of 154 cases) were treated, 26 in the standard arm and 23 in the bevacizumab arm. ORR was seen in 10 out of 36 evaluable cases (27.7%), i.e. 4/18 standard arm cases and 6/18 bevacizumab arm cases. Two-year EFS was 27.3% (95% confidence interval [CI] 13.9–42.5) for all NRSTS patients, i.e. 34.9% (95% CI 14.6–56.2) for bevacizumab arm and 22.9% (95% CI 7.1–43.9) for standard arm (p-value = 0.19). Three-year OS (median follow-up 48.6 months) was 35.2%, with no differences in the two arms. Time to event and time to death were 16.3 and 17.2 months for bevacizumab arm and 2.1 and 7.6 months for standard arm, respectively. Patients not receiving any local treatment on primary disease had a worse outcome as compared to others. Treatment results were better for patients receiving surgical resection and worse for those who did not receive any specific treatment. Conclusion: The addition of the anti-angiogenic agent to the standard chemotherapy did not show statistically significant improvement in survival in metastatic NRSTS
The Impact of Radiation Therapy in Children and Adolescents With Metastatic Rhabdomyosarcoma
No full textPurpose: There is limited evidence to define the role of radiation therapy in children with metastatic rhabdomyosarcoma (mRMS). In the international BERNIE study, children with mRMS or non-RMS soft tissue sarcoma were randomized to receive standard chemotherapy with or without bevacizumab, with radiation therapy to all disease sites recommended after chemotherapy cycle 6. We retrospectively evaluated the impact of radiation therapy on survival in the mRMS cohort. Methods and Materials: Patients were grouped according to the radiation therapy they received: radical, partial, or none. Radical irradiation was defined as radiation therapy delivered to all disease sites, unless a site was completely surgically resected. Partial irradiation was defined as radiation therapy to ≥1, but not all, disease sites. Landmark analysis excluded patients with an event before day 221. Overall survival (OS) and event-free survival (EFS) were modeled using Cox proportional hazards models. Results: Of 102 patients with mRMS, 97 were included in the analysis for OS and 85 for EFS. Overall, 27 patients received radical irradiation, 46 partial irradiation, and 24 no irradiation. EFS was not significantly different among patient groups after adjustment for prognostic factors (hazard ratio [HR] = 0.520; P = .054 for any vs no irradiation). Radiation therapy was associated with improved OS compared with no radiation therapy (adjusted HR = 0.249; P = .00025), with OS being greater for radical versus partial irradiation (HR = 0.245; P = .039). The 3-year OS rate was 84%, 54%, and 23% for patients receiving radical, partial, and no irradiation, respectively. Radical treatment (surgery, irradiation, or both) of the primary site improved EFS and OS compared with no treatment. Conclusions: These findings demonstrate variability in the application of radiation therapy for mRMS and support the routine use of radical treatment to the primary site. Radical irradiation to metastatic sites may further improve OS. The burden of such treatment should be balanced against prognosis; further studies are needed
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