Cell competition in liver carcinogenesis

Cell competition is now a well-established quality control strategy to optimize cell and tissue fitness in multicellular organisms.While pursuing this goal,it is also effective in selecting against altered/defective cells with putative(pre)-neoplastic potential,thereby edging the risk of cancer development.The flip side of the coin is that the molecular machinery driving cell competition can also be co-opted by neoplastic cell populations to expand unchecked,outside the boundaries of tissue homeostatic control.This review will focus on information that begins to emerge regarding the role of cell competition in liver physiology and pathology.Liver repopulation by normal transplanted hepatocytes is an interesting field of investigation in this regard.The biological coordinates of this process share many features suggesting that cell competition is a driving force for the clearance of endogenous damaged hepatocytes by normal donor-derived cells,as previously proposed.Intriguing analogies between liver repopulation and carcinogenesis will be briefly discussed and the potential dual role of cell competition,as a barrier or a spur to neoplastic development,will be considered.Cell competition is in essence a cooperative strategy organized at tissue level.One facet of such cooperative attitude is expressed in the elimination of altered cells which may represent a threat to the organismal community.On the other hand,the society of cells can be disrupted by the emergence of selfish clones,exploiting the molecular bar codes of cell competition,thereby paving their way to uncontrolled growth.

Transforming cancer cells for long-term living with cancer: An inspiring new approach

Cancer is the leading cause of human death and imposes a huge health burden. Currently, no matter what advanced therapeutic modalities or technologies are applied, it is still peculiarly rare for most cancers to be radically cured whereas therapy resistance and tumor recurrence are ever so common. The long-standing cytotoxic therapy is hard to achieve long-term tumor control, and produces side-effects or even promotes cancer progression. With growing understandings of tumor biology, we came to realize that it is possible to transform but not kill cancer cells to achieve long-term living with cancer, and directly altering cancer cells is a promising way. Remarkably, tissue microenvironment is involved in the fate determination of cancer cells. Of note, leveraging cell competition to combat malignant or therapy-resistant cells shows some therapeutic potentials. Furthermore, modulating tumor microenvironment to restore a normal state might help to transform cancer cells. Especially, reprogramming cancer-associated fibroblasts, and tumor-associated macrophages, or normalization of tumor vessel, tumor immune microenvironment, and tumor extracellular matrix or their combinations, et al., revealed some long-term therapeutic benefits. Despite the massive challenges ahead, it would be possible to transform cancer cells for long-term cancer control and living with cancer longevously. The related basic researches and corresponding therapeutic strategies are also ongoing.

Cell competition and its implications for development and cancer

Cell competition is a struggle for existence between cells in heterogeneous tissues of multicellular organisms. Loser cells, which die during cell competition, are normally viable when grown only with other loser cells, but when mixed with winner cells, they are at a growth disadvantage and undergo apoptosis. Intriguingly, several recent studies have revealed that cells bearing mutant tumor-suppressor genes, which show overgrowth and tumorigenesis in a homotypic situation, are frequently eliminated, through cell competition, from tissues in which they are surrounded by wild-type cells. Here, we focus on the regulation of cellular competitiveness and the mechanism of cell competition as inferred from two different categories of mutant cells： （1） slower-growing cells and （2） structurally defective cells. We also discuss the possible role of cell competition as an intrinsic homeostasis system through which normal cells sense and remove aberrant cells, such as precancerous cells, to maintain the integrity and normal development of tissues and organs.

Signaling interactions among neurons impact cell fitness and death in Alzheimer's disease

The pathology of Alzheimer’s disease involves a long preclinical period,where the characteristic clinical symptoms of the changes in the brain are undetectable.During the preclinical period,homeostatic mechanisms may help prevent widespread cell death.Evidence has pointed towards selective cell death of diseased neurons playing a potentially protective role.As the disease progresses,dysregulation of signaling pathways that govern cell death contributes to neurodegeneration.Aberrant activation of the c-Jun N-terminal kinase pathway has been established in human and animal models of Alzheimer’s disease caused by amyloid-beta 42-or tau-mediated neurodegeneration.Clonal mosaic studies in Drosophila that examine amyloid-beta 42 in a subset of neurons suggest complex interplay between amyloid-beta 42-expressing and wild-type cells.This review examines the role of c-Jun N-terminal kinase signaling in the context of cell competition and short-range signaling interactions between amyloid-beta 42-expressing and wild-type neurons.Cell competition is a conserved phenomenon regulating tissue integrity by assessing the fitness of cells relative to their neighbors and eliminating suboptimal cells.Somatic clones of amyloid-beta 42 that juxtapose genetically distinct neuronal cell populations show promise for studying neurodegeneration.Generating genetic mosaics with labeled clones of amyloid-beta 42-or tau-expressing and wild-type neurons will allow us to understand how short-range signaling alterations trigger cell death in neurons and thereby contribute to the progression of Alzheimer’s disease.These approaches have the potential to uncover biomarkers for early Alzheimer’s disease detection and new therapeutic targets for intervention.

Exosomal miR-485-3p derived from pancreatic ductal epithelial cells inhibits pancreatic cancer metastasis through targeting PAK1

Background:Cell competition is an important feature in pancreatic cancer(PC)progression,but the underlying mechanism remains elusive.This study aims to explore the role of exosomes derived from normal pancreatic ductal epithelial cells involved in PC progression.Methods:PC cells and pancreatic stellate cells(PSCs)were treated with exosomes isolated from pancreatic ductal epithelial cells.Cell proliferation was assessed by CCK8 assays.Cell migration and invasion were assessed by Transwell assays.PC and matched adjacent non-tumor tissue specimens were obtained from 46 patients pathologically diagnosed with PC at Peking University First Hospital from 2013 to 2017.Tissue miR-485-3p and p21-activated kinase-1(PAK1)expression was examined by real-time polymerase chain reaction(RT-PCR),and the relationship of the two was analyzed using Pearman’s product-moment correlation.The clinical significance of miR-485-3p was analyzed using the Chi-square test,Wilcoxon rank-sum test,and Fisher exact probability,respectively.The binding of miR-485-3p to PAK15’-untranslated region(5’-UTR)was examined by luciferase assay.PC cells were xenografted into nude mice as a PC metastasis model.Results:Exosomes from pancreatic ductal epithelial cells suppressed PC cell migration and invasion as well as the secretion and migration of PSCs.MiR-485-3p was enriched in the exosomes of pancreatic ductal epithelial cells but deficient in those of PC cells and PSCs,in accordance with the lower level in PSCs and PC cells than that in pancreatic ductal cells.And the mature miR-485-3p could be delivered into these cells by the exosomes secreted by normal pancreatic duct cells,to inhibit PC cell migration and invasion.Clinical data analysis showed that miR-485-3p was significantly decreased in PC tissues(P<0.05)and was negatively associated with lymphovascular invasion(P=0.044).As a direct target of miR-485-3p,PAK1 was found to exert an inhibitory effect on PC cells,and there was a significantly negative correlation between the expression levels of miR-485-3p and PAK1(r=-0.6525,P<0.0001)in PC tissues.Moreover,miR-485-3p could suppress PC metastasisin vivo by targeting p21-activated kinase-1.Conclusions:Exosomal miR-485-3p delivered by normal pancreatic ductal epithelial cells into PC cells inhibits PC metastasis by directly targeting PAK1.The restoration of miR-485-3p by exosomes or some other vehicle might be a novel approach for PC treatment.

Lyapunov stability of competitive cells dynamics in tumor mechanobiology

Poromechanics plays a key role in modelling hard and soft tissue behaviours,by providing a thermodynamic framework in which chemo-mechanical mutual interactions among fluid and solid constituents can be consistently rooted,at different scale levels.In this context,how different biological species(including cells,extra-cellular components and chemical metabolites)interplay within complex environments is studied for characterizing the mechanobiology of tumor growth,governed by intra-tumoral residual stresses that initiate mechanotransductive processes deregulating normal tissue homeostasis and leading to tissue remodelling.Despite the coupling between tumor poroelasticity and interspecific competitive dynamics has recently highlighted how microscopic cells and environment interactions influence growth-associated stresses and tumor pathophysiology,the nonlinear interlacing among biochemical factors and mechanics somehow hindered the possibility of gaining qualitative insights into cells dynamics.Motivated by this,in the present work we recover the linear poroelasticity in order to benefit of a reduced complexity,so first deriving the well-known Lyapunov stability criterion from the thermodynamic dissipation principle and then analysing the stability of the mechanical competition among cells fighting for common space and resources during cancer growth and invasion.At the end,the linear poroelastic model enriched by interspecific dynamics is also exploited to show how growth anisotropy can alter the stress field in spherical tumor masses,by thus indirectly affecting cell mechano-sensing.