A Review of Mathematical Models for the Formation of\ud Vascular Networks

Mainly two mechanisms are involved in the formation of blood vasculature: vasculogenesis and angiogenesis. The former consists of the formation of a capillary-like network from either a dispersed or a monolayered population of endothelial cells, reproducible also in vitro by specific experimental assays. The latter consists of the sprouting of new vessels from an existing capillary or post-capillary venule. Similar phenomena are also involved in the formation of the lymphatic system through a process generally called lymphangiogenesis.\ud \ud A number of mathematical approaches have analysed these phenomena. This paper reviews the different modelling procedures, with a special emphasis on their ability to reproduce the biological system and to predict measured quantities which describe the overall processes. A comparison between the different methods is also made, highlighting their specific features

Intermediate cell states in epithelial-to-mesenchymal transition

The transition of epithelial cells into a mesenchymal state (epithelial-to-mesenchymal transition or EMT) is a highly dynamic process implicated in various biological processes. During EMT, cells do not necessarily exist in ‘pure’ epithelial or mesenchymal states. There are cells with mixed (or hybrid) features of the two, which are termed as the intermediate cell states (ICSs). While the exact functions of ICS remain elusive, together with EMT it appears to play important roles in embryogenesis, tissue development, and pathological processes such as cancer metastasis. Recent single cell experiments and advanced mathematical modeling have improved our capability in identifying ICS and provided a better understanding of ICS in development and disease. Here, we review the recent findings related to the ICS in/or EMT and highlight the challenges in the identification and functional characterization of ICS

Intermediate cell states in epithelial-to-mesenchymal transition

The transition of epithelial cells into a mesenchymal state (epithelial-to-mesenchymal transition or EMT) is a highly dynamic process implicated in various biological processes. During EMT, cells do not necessarily exist in ‘pure’ epithelial or mesenchymal states. There are cells with mixed (or hybrid) features of the two, which are termed as the intermediate cell states (ICSs). While the exact functions of ICS remain elusive, together with EMT it appears to play important roles in embryogenesis, tissue development, and pathological processes such as cancer metastasis. Recent single cell experiments and advanced mathematical modeling have improved our capability in identifying ICS and provided a better understanding of ICS in development and disease. Here, we review the recent findings related to the ICS in/or EMT and highlight the challenges in the identification and functional characterization of ICS

Molecular aspects of tumor cell migration and invasion.

Cell migration and invasion are crucial steps in many physiological events. However, they are also implicated in the physiopathology of many diseases, such as cancer. To spread through the tissues, tumor cells use mechanisms that involve several molecular actors: adhesion receptor families, receptor tyrosine kinases, cytoskeleton proteins, adapter and signalling proteins interplay in a complex scenario. The balance of cellular signals for proliferation and survival responses also regulates migratory behaviours of tumor cells. To complicate the scene of crime drug resistance players can interfere thus worsening this delicate situation. The complete understanding of this molecular jungle is an impossible mission: some molecular aspects are reviewed in this paper

Anchor or Accelerate – A Study on Cancer Cell Adhesion and Motility

Cell migration and adhesion to the extracellular matrix (ECM) are crucial in many biological and pathological processes such as morphogenesis, tissue repair, inflammatory responses, survival, and cancer. Cell-matrix adhesion is mediated by the integrin family of transmembrane receptors, which not only anchor cells to their surroundings, but also transmit bidirectional signalling at the cell surface and couple the ECM to the cytoskeleton. Another group of adhesion receptors are the syndecan proteoglycans, which engage the ECM and possess signalling activity in response to a variety of ligands. Cell migration is a complex process that requires spatial and temporal coordination of adhesion, cell contractility, intracellular traffic of integrins, and matrix turnover by matrix metalloproteinases (MMPs). Thus, integrins and syndecans, as well as MMPs, play essential roles in cancer cell migration and invasion. The understanding of the cooperation of syndecans and integrins was broadened in this thesis study. The results reveal that syndecan-1 functions in concert with 21 integrin in cell adhesion to collagen, whereas syndecan-4 is essential in 21 integrin-mediated matrix contraction. Finally, oncogenic K-Ras was shown to regulate 21 integrin, membrane-type 1 MMP, and syndecan-1 and -4 expression and their cooperation in cell invasion. Epithelial-mesenchymal transition (EMT) is fundamental during embryogenesis and organ development. Activation of EMT processes, including the upregulation of mesenchymal intermediate filament protein vimentin, has also been implicated in the acquisition of a malignant phenotype by epithelial cancer cells. Members of the protein kinase C (PKC) superfamily are involved in cell migration and various integrindependent cellular functions. One aim of this work was to shed light on the role of vimentin in the regulation of integrin traffic and cell motility. In addition, the mechanism by which vimentin participates in EMT was investigated. The results show that integrin recycling and motility are dependent on the PKC–mediated phosphorylation of vimentin. In addition, vimentin was found to be a positive regulator of EMT and regulate the expression of several migratory genes. Specifically, vimentin governs the expression of receptor tyrosine kinase Axl, which is implicated in tumour growth and metastasis. Taken together, the findings described in this thesis reveal novel aspects of the complex interplay between distinct cellular components: integrins, syndecans, and the vimentin cytoskeleton, which all contribute to the regulation of human cancer cell adhesion, migration, and invasion.Siirretty Doriast

Formin proteins in normal tissues and cancer

The actin cytoskeleton is a dynamic structure that determines cell shape. Actin turnover is mandatory for migration in normal and malignant cells. In epithelial cancers invasion is frequently accompanied by epithelial to mesenchymal transition (EMT). In EMT, cancer cells acquire a migratory phenotype through transcriptional reprogramming. EMT requires substantial re-organization of actin. During the past decade, new actin regulating proteins have been discovered. Among these are members of the formin family. To study formin expression in tissues and cells, antibodies for detection of formin proteins FMNL1 (Formin-like protein 1), FMNL2 (Formin-like protein 2) and FHOD1 (Formin homology 2 domain containing protein 1) were used. The expression of formins was characterized in normal tissues and selected cancers using immunohistochemistry. The functional roles of formins were studied in cancer cell lines. We found that FMNL2 is widely expressed. It is a filopodial component in cultured melanoma cells. In clinical melanoma, FMNL2 expression has prognostic significance. FHOD1 is a formin expressed in mesenchymal cell types. FHOD1 expression is increased in oral squamous cell carcinoma (SCC) EMT. Importantly, FHOD1 participates in invasion of cultured oral SCC cells. FMNL1 expression is low in normal epithelia, but high in leukocytes and smooth muscle cells. Expression of FMNL1 can be found in carcinoma; we detected FMNL1 expressing cells in basal type of breast cancer. Our results indicate that formins are differentially expressed in normal tissues and that their expression may shift in cancer. Functionally FMNL2 and FHOD1 participate in processes related to cancer progression. Studying formins is increasingly important since they are potential drug targets.Formiinit terveissä kudoksissa ja syövässä Solujen aktiinitukiranka on dynaaminen rakenne, joka määrää solujen muodon. Solujen liikkuminen ja syöpäsolujen invaasio edellyttää huomattavaa aktiinitukirangan muokkausta. Epiteeliperäisten syöpäsolujen invaasiokykyyn liittyy monesti epiteeli-mesenkymaalinen transitio (EMT). EMT on käsitteenä tunnettu yksilön kehitysbiologiasta, jossa se on välttämätön kehon osien ja kudosten muovautumisessa. Kehityksellistä prosessia muistuttavalla tavalla syöpäsolujen EMT:ssa transkriptio muuttuu, minkä seurauksena syöpäsolut irtoavat ympäristöstään, muuttuvat pitkänomaisiksi ja tehokkaasti liikkuviksi. Muutokset edellyttävät tehokasta aktiinisäikeiden muokkausta. Yksi aktiinitukirankaa muokkaavien proteiinien perheitä ovat formiinit. Ne ovat viimeisen vuosikymmenen aikana olleet aktiivisen tutkimuksen kohteena. Formiinien keskeinen toiminto on aktiinisäikeiden muodostaminen. Tutkiaksemme formiinien ilmentymistä kudoksissa, varmistimme kolmen formiinin vasta-aineen luotettavan toimivuuden. Vasta-aineet oli valmistettu formiinien FMNL1 (Formin-like protein 1), FMNL2 (Formin-like protein 2) ja FHOD1 (Formin homology 2 domain containing protein 1) immunohistokemialliseen tunnistamiseen. Näiden vasta-aineiden avulla kartoitimme formiinien ilmentymisprofiilit normaaleissa kudoksissa, ja jatkoimme tutkimalla niiden ilmentymistä syöpäkudoksissa ja funktiota viljellyissä syöpäsoluissa. Osoitimme että FMNL2 ilmentyminen on laajaa normaalikudoksissa. FMNL2 paikantuu solukalvon ulokkeisiin viljellyissä melanoomasoluissa, ja sillä on ennusteellinen merkitys kliinisessä melanoomassa. FHOD1 puolestaan ilmentyy mesenkymaalisissa kudoskomponenteissa. FHOD1 ilmentyminen nousee suun levyepiteelikarsinooman EMT:ssa. Saatoimme solukokein osoittaa, että FHOD1 osallistuu EMT:hen liitettyihin toimintoihin. Lopuksi tutkimme FMNL1 ilmentymistä, ja totesimme sen lähes rajoittuvan valkosoluihin ja sileälihassoluihin. Terveissä epiteeleissä FMNL1 ilmentyminen on vähäinen, mutta saattaa lisääntyä basaalisessa rintasyövässä. Tuloksemme osoittavat että formiinit ilmentyvät toisistaan poikkeavalla profiililla normaaleissa kudoksissa. Lisäksi niiden ilmentyminen voi muuttua syövässä. Viljellyissä syöpäsoluissa formiinit osallistuvat syövän progressioon eli invaasiokykyä ja metastasointia edistäviin toimintoihin. Formiinien tutkiminen syövässä on entistäkin tärkeämpää, koska niille on jo löytynyt pienimolekyläärinen inhibiittori. Formiinien toiminnan inhibointi saattaa tulevaisuudessa kehittyä osaksi syövän lääkkeellistä hoitoa.Siirretty Doriast

Novel cell models to study breast tumour microenvironment and disease progression

Breast cancer is the most prevalent and deadly in woman. ER+ breast cancer represents around two-thirds of all cases and has a favourable prognosis due to good response to endocrine therapy. However, these tumours present 25% of disease relapse due to drug resistance and metastatic behaviour. Tumour progression and acquired drug resistance are modulated by the interactions between tumour cells and the surrounding microenvironment. Most models employed to address these mechanisms fail to reflect the complex tumour microenvironment and do not allow long-term monitoring of tumour progression. (...

To unite or disconnect : AmotL2 in tubulogenesis and tumor invasion

For an epithelial- or endothelial cell sheet or ‐tissue to form, individual cells must come together unite and connect. Contacts to adjacent cells and underlying matrix must be initiated, and the junctional proteins mediating the contacts must be further linked to intracellular cytoskeletal networks. By connecting neighboring cells into one unit, contractile actomyosin filaments allow for a closely interlinked, but yet dynamic tissue. Eventhough essential for developmental processes such as organ formation, the exact mechanism of how the cell‐cell junctions connect to the contractile actomyosin network has not yet been completely revealed. In the papers of this thesis, we identify the protein Angiomotin Like 2 (AmotL2 p100) as a linker between the contractile radial actin filaments and VE‐cadherin at the adherens junctions. Furthermore, AmotL2 p100 enables controlled‐ and synchronized morphological alterations of individual cells, which can further result in the creation of new tissue level structures, for example through tubulogenesis. We show the radial AmotL2‐mediated actin filaments to be crucial for force‐generation during morphological transformation and further aortic lumen expansion. Morphological transformations usually require organization and collaboration of several processes, such as formation/disassembly of cell‐cell and cell‐ECM contacts, establishment/disruption of apical-basal polarity and polymerization/disassembly of cytoskeletal filaments. Just like proper regulation of those intra‐ and inter cellular processes and –signals can result in complex structures with diverse morphologies and functionalities, deregulation of the same signals might cause devastating consequences for the function of an organ and the entire organism. In Paper IV of this thesis, we could identify a shorter-, hypoxia regulated AmotL2 p60 isoform. We show the actions of AmotL2 p60 to cause retainment of apical polarity proteins in cytoplasmic vesicles, hence preventing the establishment of apical-basal polarity. Furthermore, we could show AmotL2 p60 to weaken cell‐cell junctions and sensitize cells to growth factor stimuli. The combined actions of AmotL2 p60 cause tumor cell invasion into the surrounding extracellular matrix (ECM). In conclusion, we here provide data showing the two AmotL2 isoforms to possess entirely distinct functions, uniting cells into a multicellular structure, and disconnecting cells during tumor invasion, respectively

Characterizing phenotypic effects of Spy1 mediated lateral branching

Mammary development is a continuous and cyclic process that is under tight regulatory control from hormones and cell cycle regulators to mediate transition from the various proliferative, differential and apoptotic steps. Puberty is a time-point of high proliferation during development that has higher susceptibility to breast cancer. Spy1 is a cyclin-like protein known to regulate mammary development and increase proliferation with previous work also showing Spy1 increases tumor susceptibility and pubertal lateral side branching. ¬In this work we demonstrate that elevated levels of Spy1 in puberty significantly increase the number of lateral branches and total epithelial content in mice. Similarly, the pubertal glands saw increased levels of amphiregulin and proliferation. Furthermore, it was demonstrated that elevated Spy1 levels can increase budding in HC11 3D culture and increase total size in primary cell organoids. This data revealed the unique ability of Spy1 to manipulate developmental pathways in the mammary gland