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Mechanical Stress Impairs Mitosis Progression in Multi-Cellular Tumor Spheroids

Annaïck Desmaison, Céline Frongia, Katia Grenier, Bernard Ducommun, Valérie Lobjois, Adam J. Engler
2013 PLoS ONE  
Growing solid tumors are subjected to mechanical stress that influences their growth rate and development. However, little is known about its effects on tumor cell biology. To explore this issue, we investigated the impact of mechanical confinement on cell proliferation in MultiCellular Tumor Spheroids (MCTS), a 3D culture model that recapitulates the microenvironment, proliferative gradient, and cell-cell interactions of a tumor. Dedicated polydimethylsiloxane (PDMS) microdevices were designed
more » ... to spatially restrict MCTS growth. In this confined environment, spheroids are likely to experience mechanical stress as indicated by their modified cell morphology and density and by their relaxation upon removal from the microdevice. We show that the proliferation gradient within mechanically confined spheroids is different in comparison to MCTS grown in suspension. Furthermore, we demonstrate that a population of cells within the body of mechanically confined MCTS is arrested at mitosis. Cell morphology analysis reveals that this mitotic arrest is not caused by impaired cell rounding, but rather that confinement negatively affects bipolar spindle assembly. All together these results suggest that mechanical stress induced by progressive confinement of growing spheroids could impair mitotic progression. This study paves the way to future research to better understand the tumor cell response to mechanical cues similar to those encountered during in vivo tumor development.
doi:10.1371/journal.pone.0080447 pmid:24312473 pmcid:PMC3848935 fatcat:4euht6hn6nesnf46oss5lvwk2a

Mutations in the LHX2 gene are not a frequent cause of micro/anophthalmia

Annaïck Desmaison, Adeline Vigouroux, Claudine Rieubland, Christine Peres, Patrick Calvas, Nicolas Chassaing
2010 Molecular Vision  
Microphthalmia and anophthalmia are at the severe end of the spectrum of abnormalities in ocular development. A few genes (orthodenticle homeobox 2 [OTX2], retina and anterior neural fold homeobox [RAX], SRY-box 2 [SOX2], CEH10 homeodomain-containing homolog [CHX10], and growth differentiation factor 6 [GDF6]) have been implicated mainly in isolated micro/anophthalmia but causative mutations of these genes explain less than a quarter of these developmental defects. The essential role of the LIM
more » ... homeobox 2 (LHX2) transcription factor in early eye development has recently been documented. We postulated that mutations in this gene could lead to micro/anophthalmia, and thus performed molecular screening of its sequence in patients having micro/anophthalmia. Seventy patients having non-syndromic forms of colobomatous microphthalmia (n=25), isolated microphthalmia (n=18), or anophthalmia (n=17), and syndromic forms of micro/anophthalmia (n=10) were included in this study after negative molecular screening for OTX2, RAX, SOX2, and CHX10 mutations. Mutation screening of LHX2 was performed by direct sequencing of the coding sequences and intron/exon boundaries. Two heterozygous variants of unknown significance (c.128C>G [p.Pro43Arg]; c.776C>A [p.Pro259Gln]) were identified in LHX2 among the 70 patients. These variations were not identified in a panel of 100 control patients of mixed origins. The variation c.776C>A (p.Pro259Gln) was considered as non pathogenic by in silico analysis, while the variation c.128C>G (p.Pro43Arg) considered as deleterious by in silico analysis and was inherited from the asymptomatic father. Mutations in LHX2 do not represent a frequent cause of micro/anophthalmia.
pmid:21203406 pmcid:PMC3012651 fatcat:c5egyywd4vehnen6ys56i77eh4

Impact of physical confinement on nuclei geometry and cell division dynamics in 3D spheroids

Annaïck Desmaison, Ludivine Guillaume, Sarah Triclin, Pierre Weiss, Bernard Ducommun, Valérie Lobjois
2018 Scientific Reports  
Annaïck Desmaison was a recipient of a doctoral fellowship from ARC (Association de la Recherche contre le Cancer), Ecole de l'Inserm-Liliane Bettencourt and Fondation Bettencourt-Schueller.  ... 
doi:10.1038/s41598-018-27060-6 pmid:29884887 pmcid:PMC5993719 fatcat:645h5d5ikjbovcdvv7gldw6s3y

Structure Tensor Based Analysis of Cells and Nuclei Organization in Tissues

Wenxing Zhang, Jerome Fehrenbach, Annaick Desmaison, Valerie Lobjois, Bernard Ducommun, Pierre Weiss
2016 IEEE Transactions on Medical Imaging  
Motivation: Extracting geometrical information from large 2D or 3D biomedical images is important to better understand fundamental phenomena such as morphogenesis. We address the problem of automatically analyzing spatial organization of cells or nuclei in 2D or 3D images of tissues. This problem is challenging due to the usually low quality of microscopy images as well as their typically large sizes. Results: The structure tensor is a simple and robust descriptor that was developed to analyze
more » ... extures orientation. Contrarily to segmentation methods which rely on an object based modelling of images, the structure tensor views the sample at a macroscopic scale, like a continuum. We propose an original theoretical analysis of this tool and show that it allows quantifying two important features of nuclei in tissues: their privileged orientation as well as the ratio between the length of their main axes. A quantitative evaluation of the method is provided for synthetic and real 2D and 3D images. As an application, we analyze the nuclei orientation and anisotropy on multicellular tumor spheroids cryosections. This analysis reveals that cells are elongated in a privileged direction that is parallel to the boundary of the spheroid. Availability: Source codes are available at
doi:10.1109/tmi.2015.2470093 pmid:26292339 fatcat:wyufrij2ybbdth557lbpqx47o4

Targeted resequencing identifiesPTCH1as a major contributor to ocular developmental anomalies and extends the SOX2 regulatory network

Nicolas Chassaing, Erica E. Davis, Kelly L. McKnight, Adrienne R. Niederriter, Alexandre Causse, Véronique David, Annaïck Desmaison, Sophie Lamarre, Catherine Vincent-Delorme, Laurent Pasquier, Christine Coubes, Didier Lacombe (+8 others)
2016 Genome Research  
Ocular developmental anomalies (ODA) such as anophthalmia/microphthalmia (AM) or anterior segment dysgenesis (ASD) have an estimated combined prevalence of 3.7 in 10,000 births. Mutations in SOX2 are the most frequent contributors to severe ODA, yet account for a minority of the genetic drivers. To identify novel ODA loci, we conducted targeted highthroughput sequencing of 407 candidate genes in an initial cohort of 22 sporadic ODA patients. Patched 1 (PTCH1), an inhibitor of sonic hedgehog
more » ... ) signaling, harbored an enrichment of rare heterozygous variants in comparison to either controls, or to the other candidate genes (four missense and one frameshift); targeted resequencing of PTCH1 in a second cohort of 48 ODA patients identified two additional rare nonsynonymous changes. Using multiple transient models and a CRISPR/Cas9-generated mutant, we show physiologically relevant phenotypes altering SHH signaling and eye development upon abrogation of ptch1 in zebrafish for which in vivo complementation assays using these models showed that all six patient missense mutations affect SHH signaling. Finally, through transcriptomic and ChIP analyses, we show that SOX2 binds to an intronic domain of the PTCH1 locus to regulate PTCH1 expression, findings that were validated both in vitro and in vivo. Together, these results demonstrate that PTCH1 mutations contribute to as much as 10% of ODA, identify the SHH signaling pathway as a novel effector of SOX2 activity during human ocular development, and indicate that ODA is likely the result of overactive SHH signaling in humans harboring mutations in either PTCH1 or SOX2.
doi:10.1101/gr.196048.115 pmid:26893459 pmcid:PMC4817771 fatcat:puqgtffnenbwhebuyaxndyqh7m