Cell Contact Inhibition Research Articles

Role of the Hippo-YAP/TAZ Pathway in Epithelioid Hemangioendothelioma and its Potential as a Therapeutic Target.

Epithelioid hemangioendothelioma (EHE) is a rare malignant vascular tumor arising from vascular endothelial cells. This study delves into the molecular mechanisms underlying EHE, with a specific focus on the Hippo-YAP/TAZ pathway. EHE is characterized molecularly by transcriptional co-activator with a PDZ-motif (TAZ)-calmodulin binding transcription activator 1 (CAMTA1) or Yes-associated protein (YAP)-transcription factor E3 (TFE3) fusions. YAP/TAZ, a transcription co-activator, binds to transcription factors and regulates gene expression. The YAP/TAZ and its upstream Hippo pathway are involved in cell proliferation and cell contact inhibition, regulating organ size and carcinogenesis. In addition to oncogenic effects, dysfunction or gene duplication of the Hippo pathway results in a poor prognosis due to epithelial-mesenchymal transformation of epithelial cells, stem cell transformation, and increased drug resistance. Notably, the TAZ-CAMTA1 fusion is specific to EHE, and genetic alterations in the Hippo pathway other than this fusion gene are absent in EHE. The TAZ-CAMTA1 fusion is a promising therapeutic target. This review summarizes recent advances in EHE, focusing on the role of the Hippo-YAP/TAZ pathway in EHE and its potential as a therapeutic target for drug development.

Hypoxia and loss of GCM1 expression prevents differentiation and contact inhibition in human trophoblast stem cells.

The placenta develops alongside the embryo and nurtures fetal development to term. During the first stages of embryonic development, due to low blood circulation, the blood and ambient oxygen supply is very low (~1-2% O2) and gradually increases upon placental invasion. While a hypoxic environment is associated with stem cell self-renewal and proliferation, persistent hypoxia may have severe effects on differentiating cells and could be the underlying cause of placental disorders. We find that human trophoblast stem cells (hTSC) thrive in low oxygen, whereas differentiation of hTSC to trophoblast to syncytiotrophoblast (STB) and extravillous trophoblast (EVT) is negatively affected by hypoxic conditions. The pro-differentiation factor GCM1 (human Glial Cell Missing-1) is downregulated in low oxygen, and concordantly there is substantial reduction of GCM1-regulated genes in hypoxic conditions. Knockout of GCM1 in hTSC caused impaired EVT and STB formation and function, reduced expression of differentiation-responsive genes, and resulted in maintenance of self-renewal genes. Treatment with a PI3K inhibitor reported to reduce GCM1 protein levels likewise counteracts spontaneous or directed differentiation. Additionally, chromatin immunoprecipitation of GCM1 showed enrichment of GCM1-specific binding near key transcription factors upregulated upon differentiation including the contact inhibition factor CDKN1C. Loss of GCM1 resulted in downregulation of CDKN1C and corresponding loss of contact inhibition, implicating GCM1 in regulation of this critical process.

The phosphodiesterase 2A controls lymphatic junctional maturation via cGMP-dependent notch signaling

The molecular mechanisms by which lymphatic vessels induce cell contact inhibition are not understood. Here, we identify the cGMP-dependent phosphodiesterase 2A (PDE2A) as a selective regulator of lymphatic but not of blood endothelial contact inhibition. Conditional deletion of Pde2a in mouse embryos reveals severe lymphatic dysplasia, whereas blood vessel architecture remains unaltered. In the absence of PDE2A, human lymphatic endothelial cells fail to induce mature junctions and cell cycle arrest, whereas cGMP levels, but not cAMP levels, are increased. Loss of PDE2A-mediated cGMP hydrolysis leads to the activation of p38 signaling and downregulation of NOTCH signaling. However, DLL4-induced NOTCH activation restores junctional maturation and contact inhibition in PDE2A-deficient human lymphatic endothelial cells. In postnatal mouse mesenteries, PDE2A is specifically enriched in collecting lymphatic valves, and loss of Pde2a results in the formation of abnormal valves. Our data demonstrate that PDE2A selectively finetunes a crosstalk of cGMP, p38, and NOTCH signaling during lymphatic vessel maturation.

SPTAN1/NUMB axis senses cell density to restrain cell growth and oncogenesis through Hippo signaling.

The loss of contact inhibition is a key step during carcinogenesis. The Hippo-Yes-associated protein (Hippo/YAP) pathway is an important regulator of cell growth in a cell density-dependent manner. However, how Hippo signaling senses cell density in this context remains elusive. Here, we report that high cell density induced the phosphorylation of spectrin α chain, nonerythrocytic 1 (SPTAN1), a plasma membrane-stabilizing protein, to recruit NUMB endocytic adaptor protein isoforms 1 and 2 (NUMB1/2), which further sequestered microtubule affinity-regulating kinases (MARKs) in the plasma membrane and rendered them inaccessible for phosphorylation and inhibition of the Hippo kinases sterile 20-like kinases MST1 and MST2 (MST1/2). WW45 interaction with MST1/2 was thereby enhanced, resulting in the activation of Hippo signaling to block YAP activity for cell contact inhibition. Importantly, low cell density led to SPTAN1 dephosphorylation and NUMB cytoplasmic location, along with MST1/2 inhibition and, consequently, YAP activation. Moreover, double KO of NUMB and WW45 in the liver led to appreciable organ enlargement and rapid tumorigenesis. Interestingly, NUMB isoforms 3 and 4, which have a truncated phosphotyrosine-binding (PTB) domain and are thus unable to interact with phosphorylated SPTAN1 and activate MST1/2, were selectively upregulated in liver cancer, which correlated with YAP activation. We have thus revealed a SPTAN1/NUMB1/2 axis that acts as a cell density sensor to restrain cell growth and oncogenesis by coupling external cell-cell contact signals to intracellular Hippo signaling.

Abstract LB326: Combined inhibition of BRD4 and FAK1 as a novel therapeutic strategy for neurofibromatosis type 2 related schwannomas

Abstract Neurofibromatosis type 2 (NF2) is a rare disorder that is inherited in an autosomal-dominant manner and is attributed to the loss of heterozygosity (LOH) of the NF2 gene, which encodes for the tumor suppressor protein Merlin. Patients affected by the disease develop vestibular schwannomas (VS), meningiomas, and ependymomas resulting in high morbidity and premature mortality. To date, neurofibromatosis type 2 has no FDA-approved drug-based treatment. Merlin plays a central role in mediating cell contact inhibition (CI) of proliferation. Loss of Merlin leads to abnormal activation of multiple signaling pathways, including those regulated by small G-proteins Ras/Rac/cdc42 and the Hippo-YAP pathway. The Hippo-YAP pathway plays a major role in cell growth and organ size control and at its core is comprised of a kinase cascade that regulates the transcriptional regulator YAP. The function of YAP is crucial for VS development, and there are several mechanisms by which YAP regulates transcription. Some of these functions have been shown to involve the Bromodomain and Extra-Terminal domain (BET) proteins acting as co-factors. We have previously shown that the BET inhibitor JQ1 can selectively reduce the growth of the NF2-null schwannoma and Schwann cells in vitro and tumorigenesis in vivo. Additionally, evidence has shown that Merlin loss can lead to increased cell proliferation that it requires the activity of Focal Adhesion Kinase 1 (FAK1). We have previously demonstrated that FAK1 inhibition via Crizotinib has antiproliferative effects in NF2-null Schwann cells, and is currently in phase II clinical trials in NF2-related VS. In this study, wild-type and NF2-null Schwann cells and schwannoma cell lines were used to determine the impact on cell growth by employing the treatment with the BET inhibitor JQ1 and the FAK1 inhibitor Crizotinib. Our analysis in NF2-null Schwann cells and schwannoma cell lines shows that the combined inhibition exerts an antineoplastic effect at nanomolar concentrations. Moreover, this combination resulted in selective inhibition of NF2-null Schwann cell proliferation when compared to wild-type Schwann cells in vitro, when compared to either drug alone. Our preliminary data suggest that combined targeting of BET and FAK1 may offer a potential therapeutic option for the treatment of NF2-related schwannomas. Citation Format: Maria Alejandra Gonzalez, Joseph Kissil, Scott Troutman. Combined inhibition of BRD4 and FAK1 as a novel therapeutic strategy for neurofibromatosis type 2 related schwannomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB326.

Human umbilical cord mesenchymal stem cells conditioned medium exerts anti-tumor effects on KGN cells in a cell density-dependent manner through activation of the Hippo pathway

BackgroundThe conditioned medium from human umbilical cord mesenchymal stem cells (UCMSCs-CM) provides a new cell-free therapy for tumors due to its unique secretome. However, there are many contradictory reports about the effect of UCMSCs-CM on tumor cells. The loss of contact inhibition is a common characteristic of tumor cells. A relationship between the effect of UCMSCs-CM on tumor cells and contact inhibition in tumor cells is rarely concerned. Whether the effect of UCMSCs-CM on tumor cells is affected by cell density? Here, we explored the effect of UCMSCs-CM on granulosa tumor cell line (KGN) cells at low or high density.MethodsGrowth curve and CCK8 assay were used to assess cell proliferation and viability. Scratch wound and matrigel invasion assay were implicated to detect cell motility of KGN cells. UCMSCs-CM effects on cell cycle, apoptosis and pathway-related proteins were investigated by flow cytometry, TUNEL assay, western blot and immunofluorescence analysis respectively.ResultsIn growth curve analysis, before KGN cells proliferated into confluence, UCMSCs-CM had no effect on cell proliferation. However, once the cells proliferate to contact each other, UCMSCs-CM significantly inhibited proliferation. Meanwhile, when KGN cells were implanted at high density, UCMSCs-CM could induce cell cycle arrest at G1 phase, inhibit cell migration, invasion and promote apoptosis. While it had no similar effect on KGN cells implanted at low density. In mechanism, the UCMSCs-CM treatment activated the Hippo pathway when KGN cells were implanted at high density. Consistently, the MST1/2 inhibitor, XMU-MP-1, inhibited the activation of the Hippo pathway induced by UCMSCs-CM treatment and accordingly declined the anti-tumor effect of UCMSCs-CM on KGN cells.ConclusionsThe effect of UCMSCs-CM on tumor cells is affected by cell density. UCMSCs-CM exerted anti-tumor effect on KGN cells by activating Hippo pathway to restore contact inhibition. Our results suggest that UCMSCs-CM is a promising therapeutic candidate for GCT treatment.

A computational framework for testing hypotheses of the minimal mechanical requirements for cell aggregation using early annual killifish embryogenesis as a model.

Introduction: Deciphering the biological and physical requirements for the outset of multicellularity is limited to few experimental models. The early embryonic development of annual killifish represents an almost unique opportunity to investigate de novo cellular aggregation in a vertebrate model. As an adaptation to seasonal drought, annual killifish employs a unique developmental pattern in which embryogenesis occurs only after undifferentiated embryonic cells have completed epiboly and dispersed in low density on the egg surface. Therefore, the first stage of embryogenesis requires the congregation of embryonic cells at one pole of the egg to form a single aggregate that later gives rise to the embryo proper. This unique process presents an opportunity to dissect the self-organizing principles involved in early organization of embryonic stem cells. Indeed, the physical and biological processes required to form the aggregate of embryonic cells are currently unknown. Methods: Here, we developed an in silico, agent-based biophysical model that allows testing how cell-specific and environmental properties could determine the aggregation dynamics of early Killifish embryogenesis. In a forward engineering approach, we then proceeded to test two hypotheses for cell aggregation (cell-autonomous and a simple taxis model) as a proof of concept of modeling feasibility. In a first approach (cell autonomous system), we considered how intrinsic biophysical properties of the cells such as motility, polarity, density, and the interplay between cell adhesion and contact inhibition of locomotion drive cell aggregation into self-organized clusters. Second, we included guidance of cell migration through a simple taxis mechanism to resemble the activity of an organizing center found in several developmental models. Results: Our numerical simulations showed that random migration combined with low cell-cell adhesion is sufficient to maintain cells in dispersion and that aggregation can indeed arise spontaneously under a limited set of conditions, but, without environmental guidance, the dynamics and resulting structures do not recapitulate in vivo observations. Discussion: Thus, an environmental guidance cue seems to be required for correct execution of early aggregation in early killifish development. However, the nature of this cue (e.g., chemical or mechanical) can only be determined experimentally. Our model provides a predictive tool that could be used to better characterize the process and, importantly, to design informed experimental strategies.

Chronic PFOA exposure in vitro causes acquisition of multiple tumor cell characteristics in rat liver cells

Perfluorooctanoic acid (PFOA) is tumorigenic in rats and mice and potentially tumorigenic in humans. Here, we studied long-term PFOA exposure with an in vitro transformation model using the rat liver epithelial cell, TRL 1215. Cells were cultured in 10 μM (T10), 50 μM (T50) and 100 μM (T100) PFOA for 38 weeks and compared to passage-matched control cells. T100 cells showed morphological changes, loss of cell contact inhibition, formation of multinucleated giant and spindle-shaped cells. T10, T50, and T100 cells showed increased LC50 values 20%, 29% to 35% above control with acute PFOA treatment, indicating a resistance to PFOA toxicity. PFOA-treated cells showed increases in Matrix metalloproteinase-9 secretion, cell migration, and developed more and larger colonies in soft agar. Microarray data showed Myc pathway activation at T50 and T100, associating Myc upregulation with PFOA-induced morphological transformation. Western blot confirmed that PFOA produced significant increases in c-MYC protein expression in a time- and concentration-related manner. Tumor invasion indicators MMP-2 and MMP-9, cell cycle regulator cyclin D1, and oxidative stress protein GST were all significantly overexpressed in T100 cells. Taken together, chronic in vitro PFOA exposure produced multiple cell characteristics of malignant progression and differential gene expression changes suggestive of rat liver cell transformation.

NFATc1 Regulation of Dexamethasone-Induced TGFB2 Expression Is Cell Cycle Dependent in Trabecular Meshwork Cells.

Although elevated TGFβ2 levels appear to be a causative factor in glaucoma pathogenesis, little is known about how TGFβ2 expression is regulated in the trabecular meshwork (TM). Here, we investigated if activation of the cytokine regulator NFATc1 controlled transcription of TGFβ2 in human TM cells by using dexamethasone (DEX) to induce NFATc1 activity. The study used both proliferating and cell cycle arrested quiescent cells. Cell cycle arrest was achieved by either cell-cell contact inhibition or serum starvation. β-catenin staining and p21 and Ki-67 nuclear labeling were used to verify the formation of cell-cell contacts and activity of the cell cycle. NFATc1 inhibitors cyclosporine A (CsA) or 11R-VIVIT were used to determine the role of NFATc1. mRNA levels were determined by RT-qPCR. DEX increased TGFβ2 mRNA expression by 3.5-fold in proliferating cells but not in quiescent cells or serum-starved cells, and both CsA and 11R-VIVIT inhibited this increase. In contrast, the expression of other DEX/NFATc1-induced mRNAs (myocilin and β3 integrin) occurred regardless of the proliferative state of the cells. These studies show that NAFTc1 regulates TGFβ2 transcription in TM cells and reveals a previously unknown connection between the TM cell cycle and modulation of gene expression by NFATc1 and/or DEX in TM cells.

Pattern formation via cell–cell adhesion and contact inhibition of locomotion in active matter

Cell wetting and dewetting in soft substrates present a collection of non-cohesive and cohesive patterns. Prediction of this wide diversity is of critical importance in order to design experiments with polar active matter under confinement. Although in vivo, cells and the extracellular matrix (ECM) are enfolded by flexible substrates, at experimental realizations, hard boundaries are frequently employed. Here, the elastic forces exerted by the cells and the ECM—between a deformable layer and a solid substrate—allow to recast a continuum model that takes account of heterogeneous exchanges such as cell–substrate adhesion and averaged repolarization due to contact inhibition of locomotion (CIL). Theoretical results show that cell aggregation is enforced as increasing cell–cell adhesion and decreasing CIL strength and exhibit different phases from gaseous states to polar liquids and 3D clusters, in agreement with recent reports. Cell diffusion grows as cell rigidity increases, and reduction of ECM stiffness eases cell aggregation and cluster formation. The findings of this work provide the mechanisms that drive and resist active unstable states and can be used as a predictability tool in cell clustering and cell migration experiments.

Dental Stem Cells SV40, a new cell line developed in vitro from human stem cells of the apical papilla.

To establish and fully characterize a new cell line from human stem cells of the apical papilla (SCAPs) through immortalization with an SV40 large T antigen. Human SCAPs were isolated and transfected with an SV40 large T antigen and treated with puromycin to select the infected population. Expression of human mesenchymal surface markers CD73, CD90 and CD105 was assessed in the new cell line named Dental Stem Cells SV40 (DSCS) by flow cytometry at early and late passages. Cell contact inhibition and proliferation were also analysed. To evaluate trilineage differentiation, quantitative polymerase chain reaction and histological staining were performed. DSCS cell flow cytometry confirmed the expression of mesenchymal surface markers even in late passages [100% positive for CD73 and CD90 and 98.9% for CD105 at passage (P) 25]. Fewer than 0.5% were positive for haematopoietic cell markers (CD45 and CD34). DSCS cells also showed increased proliferation when compared to the primary culture after 48 h, with a doubling time of 23.46 h for DSCS cells and 40.31 h for SCAPs, and retained the capacity to grow for >45 passages (150 population doubling) and their spindle-shaped morphology. Trilineage differentiation potential was confirmed through histochemical staining and gene expression of the chondrogenic markers SOX9 and COL2A1, adipogenic markers CEBPA and LPL, and osteogenic markers COL1A1 and ALPL. The new cell line derived from human SCAPs has multipotency, retains its morphology and expression of mesenchymal surface markers and shows higher proliferative capacity even at late passages (P45). DSCS cells can be used for in vitro study of root development and to achieve a better understanding of the regenerative mechanisms.

Establishment and characterization of an immortalized bovine intestinal epithelial cell line.

Primary bovine intestinal epithelial cells (PBIECs) are an important model for studying the molecular and pathogenic mechanisms of diseases affecting the bovine intestine. It is difficult to obtain and grow PBIECs stably, and their short lifespan greatly limits their application. Therefore, the purpose of this study was to create a cell line for exploring the mechanisms of pathogen infection in bovine intestinal epithelial cells in vitro. We isolated and cultured PBIECs and established an immortalized BIEC line by transfecting PBIECs with the pCI-neo-hTERT (human telomerase reverse transcriptase) recombinant plasmid. The immortalized cell line (BIECs-21) retained structure and function similar to that of the PBIECs. The marker proteins characteristic of epithelial cells, cytokeratin 18 (CK18), occludin, zonula occludens protein 1 (ZO-1), E-cadherin and enterokinase, were all positive in the immortalized cell line, and the cell structure, growth rate, karyotype, serum dependence and contact inhibition were normal. The hTERT gene was successfully transferred into BIECs-21 where it remained stable and was highly expressed. The transport of short-chain fatty acids and glucose uptake by the BIECs-21 was consistent with PBIECs, and we showed that they could be infected with the intestinal parasite, Neospora caninum. The immortalized BIECs-21, which have exceeded 80 passages, were structurally and functionally similar to the primary BIECs and thus provide a valuable research tool for investigating the mechanism of pathogen infection of the bovine intestinal epithelium in vitro.

Combination of Caffeic Acid Phenethyl Ester and Crocin Realign Potential Molecular Markers in U87-MG Glioma Cells

Glial tumors are the most common primary malignant central nervous system tumors. They are hard to treat, not only because of the deregulation in multiple pathways but also because they are not contained in a well-defined mass with clear borders. The use of a single therapeutic agent to target gliomas has yielded unsatisfactory results. A combination of molecules targeting multiple pathways may prove to be a better alternative. The effect of caffeic acid phenethyl ester and crocin on the proliferation and death of U87-MG cells over a concentration range was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays. A colony formation assay was used to measure the effect of caffeic acid phenethyl ester and crocin on contact inhibition and anchorage independence ability of U87-MG cells. Furthermore, apoptosis in U87-MG cells was analyzed by propidium iodide assay. Real-time polymerase chain reaction and Western blotting were performed to determine the expression level of p53, epidermal growth factor receptor, and proliferating cell nuclear antigen. Caffeic acid phenethyl ester and crocin when used in combination present an anticancer potential for glioma. These molecules, in combination, inhibit proliferation and induce apoptosis in U87-MG glioma cells. Our results provide evidence that combination treatment realigns the expression paradigm of p53, epidermal growth factor receptor, and proliferating cell nuclear antigen in cotreated U87-MG cells. The combination of caffeic acid phenethyl ester and crocin led to inhibition in glioma cell proliferation and might prove to be an effective adjunct to the therapies in vogue.

Rock inhibitors and antisense oligonucleotides for Fuchs corneal endothelial dystrophy

AbstractFuchs corneal dystrophy (FECD) is the most common primary cause of corneal endothelial dystrophy. FECD is a complex disease where interaction between multiple genetic and environmental factors results in endothelial cells apoptosis and atypical extracellular matrix deposition. Due to the shortage of donor tissue, and high costs of transplants, a topical therapy for treating corneal endothelial dysfunction is urgently required. The topical treatment of several agents has been investigated as therapies for FECD, by the promotion of endothelial cell proliferation and migration, in experimental models of the disorder. ROCK1 and ROCK2 inhibition promotes cell adhesion, prevents apoptosis, and enhances the proliferation of and human corneal endothelial cells. These therapies have involved the knockdown of connexin by siRNA, the release of cell–cell contact inhibition with EDTA, and inhibition of Rho‐associated protein kinase (ROCK) with Y‐27632. Recently several papers showed that Ripasudil, a rho kinase inhibitor, has been shown to promote corneal endothelial wound healing in animal models and in clinical trials. An antisense oligonucleotide (ASO) has also been developed to target the repetitive RNA. This has been shown to decrease foci formation and reversal of misplacing in ex‐vivo FECD specimens. Antisense oligonucleotides (ASO) reduced the RNA aggregates and their toxic downstream events in patient cells. ASO has to be designed to target a particular genetic mutation. This new medical‐based regenerative therapy may provide a less invasive and more effective method for treating patients with FECD.

The Regulation of the Hippo Pathway by Intercellular Junction Proteins.

The Hippo pathway is an evolutionarily conserved pathway that serves to promote cell death and differentiation while inhibiting cellular proliferation across species. The downstream effectors of this pathway, yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), are considered vital in promoting the output of the Hippo pathway, with activation of upstream kinases negatively regulating YAP/TAZ activity. The upstream regulation of the Hippo pathway is not entirely understood on a molecular level. However, several studies have shown that numerous cellular and non-cellular mechanisms such as cell polarity, contact inhibition, soluble factors, mechanical forces, and metabolism can convey external stimuli to the intracellular kinase cascade, promoting the activation of key components of the Hippo pathway and therefore regulating the subcellular localisation and protein activity of YAP/TAZ. This review will summarise what we have learnt about the role of intercellular junction-associated proteins in the activation of this pathway, including adherens junctions and tight junctions, and in particular our latest findings about the desmosomal components, including desmoglein-3 (DSG3), in the regulation of YAP signalling, phosphorylation, and subcellular translocation.

Loss of contact inhibition of locomotion in the absence of JAM-A promotes entotic cell engulfment

SummaryEntosis is a cell competition process during which tumor cells engulf other tumor cells. It is initiated by metabolic stress or by loss of matrix adhesion, and it provides the winning cell with resources derived from the internalized cell. Using micropatterns as substrates for single cell migration, we find that the depletion of the cell adhesion receptor JAM-A strongly increases the rate of entosis in matrix-adherent cells. The activity of JAM-A in suppressing entosis depends on phosphorylation at Tyr280, which is a binding site for C-terminal Src kinase, and which we have previously found to regulate tumor cell motility and contact inhibition of locomotion (CIL). Loss of JAM-A triggers entosis in matrix-adherent cells but not matrix-deprived cells. Our findings strongly suggest that the increased motility and the perturbed CIL response after the depletion of JAM-A promote entotic cell engulfment, and they link a dysregulation of CIL to entosis in breast cancer cells.

Abstract 2263: The role of E-Cadherin mediated cell division in promoting collective colon cancer cell migration

Abstract Collective cell migration is the cell cohort migrates toward the direction. Other than single cell migration, collective cell migration requires cell-cell connection with E-cadherin, however, E-cadherin is the epithelial marker in epithelial mesenchymal transition and acts as tumor suppressor function. Therefore, the role of E-cadherin in collective cell migration is still under investigated. In the collected cells, cell migration and cell division are coordinated for the cohort motility, the mechanism is still not clear. This study is to investigate the role of E-cadherin orientation in cell division dependent collective cell migration. Colorectal cancer cell line HT29 with epithelial morphology were used and treated with Cetuximab and Dasatinib to inhibit EGFR and Src activity. Cells were also incubated on fibronectin to monitor the matrix dependent environment. The polarity of E-cadherin distribution and cell contact inhibition were defined and detected by Immunofluorescence. The molecular expression of p-FAK, CDK4, and cell proliferation marker, Ki67 were revealed by Immunofluorescence confocal microscopy and Western blot. The collective cell migration is analyzed and compared by wound healing and transwell assay. In the results, the polarized distribution of E-cadherin in leading cells which revealed pFAK expression on the cell membrane was associated with Ki67 and CDK4 positive proliferated cells. When cells were grown on fibronectin, the proliferated cells in the leading were decreased. When cells were treated with cetuximab, the E-cadherin distribution were not changed and had fewer effect on cell migration. However, dasatinib treatment can modulate E-cadherin orientation and suppress cell proliferation and cell migration. These results suggested modulate E-cadherin orientation such as Src inhibition can be the potential treatment strategy in colon cancer Citation Format: Yu-Lin Li, Yu-Cheng Weng, Viriya Adhiguna Winarso, Yi-Wen Lu, Hui Min Koo, Xiang-Ling Hou, Kai-Yu Tseng, Wei-Ting Chao. The role of E-Cadherin mediated cell division in promoting collective colon cancer cell migration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2263.

Abstract 1001: Investigates the role of vesicle trafficking in E-cadherin dynamics in collective migrated colon cancer cells

Abstract Cell adherens junction plays an important role in cell communication and regulation. E-cadherin is an important protein as adherens junctions. Loss of E-cadherin leads to epithelial cells transit to mesenchymal cells. Studies has demonstrated that E-cadherin dominates cell contact inhibition, which plays an important role in cell growth, however, recent studies demonstrated collective cell migration required E-cadherin expression escaping cell growth inhibition is important in metastasis. E-cadherin dynamics has been shown to be regulated by vesicle trafficking, however, the detail mechanism of vesicle trafficking in collective cell migration is not clear. This study is investigating the relationship between the endocytosis mechanism of E-cadherin and its dynamic expression resulting in collective cell migration. The expression of E-cadherin was controlled by regulating the concentration of calcium and EDTA to observe its effect on cell-cell contact. Through Transmission electron microscope, immunofluorescence staining and western blotting to observe the relationship between vesicle trafficking and E-cadherin. Collective cell migration is analyzed by transwell assay. When calcium concentration was increased, the E-cadherin in cell-cell contacts became stronger. Conversely, when EDTA concentration was increased, the E-cadherin in the cell-cell contacts became weaker. Meanwhile, we found colocalization occurs in Rab5 and Rab11 with E-cadherin. Besides, intracellular E-cadherin transported to the lysosome for degradation was also observed. We identified the role of E-cadherin is regulated in endocytosis mechanism and at cell-cell contacts through different regulatory, which provides a basis for the future use of drugs to affect E-cadherin expression to inhibit collective cell migration. Citation Format: Hui Min Koo, Xiang-Ling Hou, Yu-Lin Li, Yi-Wen Lu, Viriya Adhiguna Winarso, Yu-Cheng Weng, Wei-Ting Chao. Investigates the role of vesicle trafficking in E-cadherin dynamics in collective migrated colon cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1001.

Disruption of Toxoplasma gondii-Induced Host Cell DNA Replication Is Dependent on Contact Inhibition and Host Cell Type.

ABSTRACTThe protozoan Toxoplasma gondii is a highly successful obligate intracellular parasite that, upon invasion of its host cell, releases an array of host-modulating protein effectors to counter host defenses and further its own replication and dissemination. Early studies investigating the impact of T. gondii infection on host cell function revealed that this parasite can force normally quiescent cells to activate their cell cycle program. Prior reports by two independent groups identified the dense granule protein effector HCE1/TEEGR as being solely responsible for driving host cell transcriptional changes through its direct interaction with the cyclin E regulatory complex DP1 and associated transcription factors. Our group independently identified HCE1/TEEGR through the presence of distinct repeated regions found in a number of host nuclear targeted parasite effectors and verified its central role in initiating host cell cycle changes. Additionally, we report here the time-resolved kinetics of host cell cycle transition in response to HCE1/TEEGR, using the fluorescence ubiquitination cell cycle indicator reporter line (FUCCI), and reveal the existence of a block in S-phase progression and host DNA synthesis in several cell lines commonly used in the study of T. gondii. Importantly, we have observed that this S-phase block is not due to additional dense granule effectors but rather is dependent on the host cell line background and contact inhibition status of the host monolayer in vitro. This work highlights intriguing differences in the host response to reprogramming by the parasite and raises interesting questions regarding how parasite effectors differentially manipulate the host cell depending on the in vitro or in vivo context.IMPORTANCE Toxoplasma gondii chronically infects approximately one-third of the global population and can produce severe pathology in immunologically immature or compromised individuals. During infection, this parasite releases numerous host-targeted effector proteins that can dramatically alter the expression of a variety of host genes. A better understanding of parasite effectors and their host targets has the potential to not only provide ways to control infection but also inform us about our own basic biology. One host pathway that has been known to be altered by T. gondii infection is the cell cycle, and prior reports have identified a parasite effector, known as HCE1/TEEGR, as being responsible. In this report, we further our understanding of the kinetics of cell cycle transition induced by this effector and show that the capacity of HCE1/TEEGR to induce host cell DNA synthesis is dependent on both the cell type and the status of contact inhibition.

Low Energy Status under Methionine Restriction Is Essentially Independent of Proliferation or Cell Contact Inhibition.

Nonlimited proliferation is one of the most striking features of neoplastic cells. The basis of cell division is the sufficient presence of mass (amino acids) and energy (ATP and NADH). A sophisticated intracellular network permanently measures the mass and energy levels. Thus, in vivo restrictions in the form of amino acid, protein, or caloric restrictions strongly affect absolute lifespan and age-associated diseases such as cancer. The induction of permanent low energy metabolism (LEM) is essential in this process. The murine cell line L929 responds to methionine restriction (MetR) for a short time period with LEM at the metabolic level defined by a characteristic fingerprint consisting of the molecules acetoacetate, creatine, spermidine, GSSG, UDP-glucose, pantothenate, and ATP. Here, we used mass spectrometry (LC/MS) to investigate the influence of proliferation and contact inhibition on the energy status of cells. Interestingly, the energy status was essentially independent of proliferation or contact inhibition. LC/MS analyses showed that in full medium, the cells maintain active and energetic metabolism for optional proliferation. In contrast, MetR induced LEM independently of proliferation or contact inhibition. These results are important for cell behaviour under MetR and for the optional application of restrictions in cancer therapy.