Hyperinsulinemia Drives Epithelial Tumorigenesis by Abrogating Cell Competition

Tumor initiation and early tumorigenesis: molecular mechanisms and interventional targets

Tumorigenesis is a multistep process, with oncogenic mutations in a normal cell conferring clonal advantage as the initial event. However, despite pervasive somatic mutations and clonal expansion in normal tissues, their transformation into cancer remains a rare event, indicating the presence of additional driver events for progression to an irreversible, highly heterogeneous, and invasive lesion. Recently, researchers are emphasizing the mechanisms of environmental tumor risk factors and epigenetic alterations that are profoundly influencing early clonal expansion and malignant evolution, independently of inducing mutations. Additionally, clonal evolution in tumorigenesis reflects a multifaceted interplay between cell-intrinsic identities and various cell-extrinsic factors that exert selective pressures to either restrain uncontrolled proliferation or allow specific clones to progress into tumors. However, the mechanisms by which driver events induce both intrinsic cellular competency and remodel environmental stress to facilitate malignant transformation are not fully understood. In this review, we summarize the genetic, epigenetic, and external driver events, and their effects on the co-evolution of the transformed cells and their ecosystem during tumor initiation and early malignant evolution. A deeper understanding of the earliest molecular events holds promise for translational applications, predicting individuals at high-risk of tumor and developing strategies to intercept malignant transformation.

Cell competition and the regulation of protein homeostasis

The process of embryonic development involves remarkable cellular plasticity, which governs the coordination between cells necessary to build an organism. One role of this plasticity is to ensure that when aberrant cells are eliminated, growth adjustment occurs so that the size of the tissue is maintained. An important regulator of cellular plasticity that ensures cellular cooperation is a fitness-sensing mechanism termed cell competition. During cell competition, cells with defects that lower fitness but do not affect viability, such as those that cause impaired signal transduction, slower cellular growth, mitochondrial dysregulation or impaired protein homeostasis, are killed when surrounded by fitter cells. This is accompanied by the compensatory proliferation of the surviving cells. The underlying factors and mechanisms that demarcate certain cells as less fit than their neighbouring cells and losers of cell competition are still relatively unknown. Recent evidence has pointed to mitochondrial defects and proteotoxic stress as important hallmarks of these loser cells. Here, we review recent advances in this area, focussing on the role of mitochondrial activity and protein homeostasis as major mechanisms determining competitive cell fitness during development and the importance of cell proteostasis in determining cell fitness.

Toward a predictive understanding of epithelial cell death

Epithelial cell death is highly prevalent during development and tissue homeostasis. While we have a rather good understanding of the molecular regulators of programmed cell death, especially for apoptosis, we still fail to predict when, where, how many and which specific cells will die in a tissue. This likely relies on the much more complex picture of apoptosis regulation in a tissular and epithelial context, which entails cell autonomous but also non-cell autonomous factors, diverse feedback and multiple layers of regulation of the commitment to apoptosis. In this review, we illustrate this complexity of epithelial apoptosis regulation by describing these different layers of control, all demonstrating that local cell death probability is a complex emerging feature. We first focus on non-cell autonomous factors that can locally modulate the rate of cell death, including cell competition, mechanical input and geometry as well as systemic effects. We then describe the multiple feedback mechanisms generated by cell death itself. We also outline the multiple layers of regulation of epithelial cell death, including the coordination of extrusion and regulation occurring downstream of effector caspases. Eventually, we propose a roadmap to reach a more predictive understanding of cell death regulation in an epithelial context.

Physical Activity, Insulin Resistance and Cancer: A Systematic Review

INTRODUCTION

Insulin resistance (IR), a key aspect of type 2 diabetes and a defining characteristic of obesity and its associated conditions, emerges as a mechanistic pathway potentially implicated in cancer pathophysiology. This presents an appealing intervention target for cancer patients. The objective of this study is to conduct a systematic review, examining the scientific evidence regarding the impact of physical activity on modifying insulin resistance in individuals with cancer.

METHODS

The selection criteria were specific: only randomized controlled clinical trials published in the last 13 years and written in English or Spanish were included. The databases utilized for the search included PubMed, Scopus, Cochrane Library, EBSCO, and WEB OF SCIENCE. The protocol for this review was duly registered in the International Register of Systematic Reviews (CRD42023435002). The final search was conducted on 14 May 2023.

RESULTS

The outcomes were assessed using the tool proposed by the Cochrane Handbook to evaluate the risk of bias in the included studies. Among the 12 studies incorporated, 8 demonstrated a low risk of bias, two had an unclear risk of bias, and the remaining two showed a high risk of bias. The variety of exercise types used across all studies was extensive, making definitive conclusions challenging. Physical activity was linked to enhanced insulin sensitivity in seven studies, while five studies showed no significant changes in insulin resistance between the intervention and control groups. Importantly, none of the interventions employed in the included studies exhibited adverse effects on the study participants.

CONCLUSIONS

The role of exercise as a medicine against insulin resistance has been evidenced in many different studies, mostly related to obesity and cardiovascular diseases. Engaging in physical activity could be a healthy option to combat the effects of insulin resistance in cancer patients, although evidence is weak and limited, according to the results of our systemic review. We further found that literature is lacking at the level of optimal doses, timing, and type of exercise. More studies are needed with more defined PA programs in type and length.

RF, Mohan H, Annaert W, Chaudhary V. Maintenance of proteostasis by Drosophila Rer1 is essential for competitive cell survival and Myc-driven overgrowth

Defects in protein homeostasis can induce proteotoxic stress, affecting cellular fitness and, consequently, overall tissue health. In various growing tissues, cell competition based mechanisms facilitate detection and elimination of these compromised, often referred to as 'loser', cells by the healthier neighbors. The precise connection between proteotoxic stress and competitive cell survival remains largely elusive. Here, we reveal the function of an endoplasmic reticulum (ER) and Golgi localized protein Rer1 in the regulation of protein homeostasis in the developing Drosophila wing epithelium. Our results show that loss of Rer1 leads to proteotoxic stress and PERK-mediated phosphorylation of eukaryotic initiation factor 2α. Clonal analysis showed that rer1 mutant cells are identified as losers and eliminated through cell competition. Interestingly, we find that Rer1 levels are upregulated upon Myc-overexpression that causes overgrowth, albeit under high proteotoxic stress. Our results suggest that increased levels of Rer1 provide cytoprotection to Myc-overexpressing cells by alleviating the proteotoxic stress and thereby supporting Myc-driven overgrowth. In summary, these observations demonstrate that Rer1 acts as a novel regulator of proteostasis in Drosophila and reveal its role in competitive cell survival.

Cell competition: emerging signaling and unsolved questions

Multicellular communities have an intrinsic mechanism that optimizes their structure and function via cell-cell communication. One of the driving forces for such self-organization of the multicellular system is cell competition, the elimination of viable unfit or deleterious cells via cell-cell interaction. Studies in Drosophila and mammals have identified multiple mechanisms of cell competition caused by different types of mutations or cellular changes. Intriguingly, recent studies have found that different types of "losers" of cell competition commonly show reduced protein synthesis. In Drosophila, the reduction in protein synthesis levels in loser cells is caused by phosphorylation of the translation initiation factor eIF2α via a bZip transcription factor Xrp1. Given that a variety of cellular stresses converge on eIF2α phosphorylation and thus global inhibition of protein synthesis, cell competition may be a machinery that optimizes multicellular fitness by removing stressed cells. In this review, we summarize and discuss emerging signaling mechanisms and critical unsolved questions, as well as the role of protein synthesis in cell competition.

Cell competition and cancer from Drosophila to mammals

Throughout an individual's life, somatic cells acquire cancer-associated mutations. A fraction of these mutations trigger tumour formation, a phenomenon partly driven by the interplay of mutant and wild-type cell clones competing for dominance; conversely, other mutations function against tumour initiation. This mechanism of 'cell competition', can shift clone dynamics by evaluating the relative status of clonal populations, promoting 'winners' and eliminating 'losers'. This review examines the role of cell competition in the context of tumorigenesis, tumour progression and therapeutic intervention.

Differential Ire1 determines loser cell fate in tumor-suppressive cell competition

Tumor-suppressive cell competition (TSCC) is a conserved surveillance mechanism in which neighboring cells actively eliminate oncogenic cells. Despite overwhelming studies showing that the unfolded protein response (UPR) is dysregulated in various tumors, it remains debatable whether the UPR restrains or promotes tumorigenesis. Here, using Drosophila eye epithelium as a model, we uncover a surprising decisive role of the Ire1 branch of the UPR in regulating cell polarity gene scribble (scrib) loss-induced TSCC. Both mutation and hyperactivation of Ire1 accelerate elimination of scrib clones via inducing apoptosis and autophagy, respectively. Unexpectedly, relative Ire1 activity is also crucial for determining loser cell fate, as dysregulating Ire1 signaling in the surrounding healthy cells reversed the "loser" status of scrib clones by decreasing their apoptosis. Furthermore, we show that Ire1 is required for cell competition in mammalian cells. Together, these findings provide molecular insights into scrib-mediated TSCC and highlight Ire1 as a key determinant of loser cell fate.

A stepwise activation model for the insulin receptor

The binding of insulin to the insulin receptor (IR) triggers a cascade of receptor conformational changes and autophosphorylation, leading to the activation of metabolic and mitogenic pathways. Recent advances in the structural and functional analyses of IR have revealed the conformations of the extracellular domains of the IR in inactive and fully activated states. However, the early activation mechanisms of this receptor remain poorly understood. The structures of partially activated IR in complex with aptamers provide clues for understanding the initial activation mechanism. In this review, we discuss the structural and functional features of IR complexed with various ligands and propose a model to explain the sequential activation mechanism. Moreover, we discuss the structures of IR complexed with biased agonists that selectively activate metabolic pathways and provide insights into the design of selective agonists and their clinical implications.

Zebrafish imaging reveals hidden oncogenic-normal cell communication during primary tumorigenesis

Oncogenic mutations drive tumorigenesis, and single cells with oncogenic mutations act as the tumor seeds that gradually evolve into fully transformed tumors. However, oncogenic cell behavior and communication with neighboring cells during primary tumorigenesis remain poorly understood. We used the zebrafish, a small vertebrate model suitable for in vivo cell biology, to address these issues. We describe the cooperative and competitive communication between oncogenic cells and neighboring cells, as revealed by our recent zebrafish imaging studies. Newly generated oncogenic cells are actively eliminated by neighboring cells in healthy epithelia, whereas oncogenic cells cooperate with their neighbors to prime tumorigenesis in unhealthy epithelia via additional mutations or inflammation. In addition, we discuss the potential of zebrafish in vivo imaging to determine the initial steps of human tumorigenesis.Key words: zebrafish, imaging, cell-cell communication, cell competition, EDAC, senescence, primary tumorigenesis.

Clonal interactions in cancer: integrating quantitative models with experimental and clinical data

Tumors consist of different genotypically distinct subpopulations-or subclones-of cells. These subclones can influence neighboring clones in a process called "clonal interaction." Conventionally, research on driver mutations in cancer has focused on their cell-autonomous effects that lead to an increase in fitness of the cells containing the driver. Recently, with the advent of improved experimental and computational technologies for investigating tumor heterogeneity and clonal dynamics, new studies have shown the importance of clonal interactions in cancer initiation, progression, and metastasis. In this review we provide an overview of clonal interactions in cancer, discussing key discoveries from a diverse range of approaches to cancer biology research. We discuss common types of clonal interactions, such as cooperation and competition, its mechanisms, and the overall effect on tumorigenesis, with important implications for tumor heterogeneity, resistance to treatment, and tumor suppression. Quantitative models-in coordination with cell culture and animal model experiments-have played a vital role in investigating the nature of clonal interactions and the complex clonal dynamics they generate. We present mathematical and computational models that can be used to represent clonal interactions and provide examples of the roles they have played in identifying and quantifying the strength of clonal interactions in experimental systems. Clonal interactions have proved difficult to observe in clinical data; however, several very recent quantitative approaches enable their detection. We conclude by discussing ways in which researchers can further integrate quantitative methods with experimental and clinical data to elucidate the critical-and often surprising-roles of clonal interactions in human cancers.

Cell Competition Shapes Metastatic Latency and Relapse

Cell competition, a fitness-sensing process, is essential for tissue homeostasis. Using cancer metastatic latency models, we show that cell competition results in the displacement of latent metastatic (Lat-M) cells from the primary tumor. Lat-M cells resist anoikis and survive as residual metastatic disease. A memodeled extracellular matrix facilitates Lat-M cell displacement and survival in circulation. Disrupting cell competition dynamics by depleting secreted protein and rich in cysteine (SPARC) reduced displacement from orthotopic tumors and attenuated metastases. In contrast, depletion of SPARC after extravasation in lung-resident Lat-M cells increased metastatic outgrowth. Furthermore, multiregional transcriptomic analyses of matched primary tumors and metachronous metastases from patients with kidney cancer identified tumor subclones with Lat-M traits. Kidney cancer enriched for these Lat-M traits had a rapid onset of metachronous metastases and significantly reduced disease-free survival. Thus, an unexpected consequence of cell competition is the displacement of cells with Lat-M potential, thereby shaping metastatic latency and relapse.

SIGNIFICANCE

We demonstrate that cell competition within the primary tumor results in the displacement of Lat-M cells. We further show the impact of altering cell competition dynamics on metastatic incidence that may guide strategies to limit metastatic recurrences. This article is highlighted in the In This Issue feature, p. 1.

Role of Glucosamine and Chondroitin in the Prevention of Cancer: A Meta-Analysis

The anti-inflammatory properties of glucosamine and chondroitin suggest that they may have potential effects in cancer prevention. We performed this meta-analysis to assess the protective function of glucosamine and/or chondroitin intake against cancer risk. We searched the PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI) databases. The odds ratio (OR), corresponding to the 95% confidence interval (95% CI), was used to assess the association between chondroitin and/or glucosamine intake and cancer risk. Thirteen studies met the inclusion criteria, with 1,690,918 participants and 55,045 cancer cases. Overall, chondroitin and/or glucosamine intake was associated with a lower risk of colorectal cancer (OR = 0.91, 95% CI, 0.87-0.94) and lung cancer (OR = 0.84, 95% CI, 0.79-0.89). Subgroup analysis supported the protective effect of different SYSADOAs (chondroitin and/or glucosamine) intake. However, the protective effect was not observed in the only chondroitin intake group and in the NSAIDs group. Our meta-analysis found that the intake of glucosamine and/or chondroitin decreased the risk of colorectal and lung cancers. Moreover, NSAIDs use may have a synergistic protective effect.

Cell-cell interactions that drive tumorigenesis in Drosophila

Cell-cell interactions within tumour microenvironment play crucial roles in tumorigenesis. Genetic mosaic techniques available in Drosophila have provided a powerful platform to study the basic principles of tumour growth and progression via cell-cell communications. This led to the identification of oncogenic cell-cell interactions triggered by endocytic dysregulation, mitochondrial dysfunction, cell polarity defects, or Src activation in Drosophila imaginal epithelia. Such oncogenic cooperations can be caused by interactions among epithelial cells, mesenchymal cells, and immune cells. Moreover, microenvironmental factors such as nutrients, local tissue structures, and endogenous growth signalling activities critically affect tumorigenesis. Dissecting various types of oncogenic cell-cell interactions at the single-cell level in Drosophila will greatly increase our understanding of how tumours progress in living animals.

PTP10D-mediated cell competition is not obligately required for elimination of polarity-deficient clones

Animal organs maintain tissue integrity and ensure removal of aberrant cells through several types of surveillance mechanisms. One prominent example is the elimination of polarity-deficient mutant cells within developing Drosophila imaginal discs. This has been proposed to require heterotypic cell competition dependent on the receptor tyrosine phosphatase PTP10D within the mutant cells. We report here experiments to test this requirement in various contexts and find that PTP10D is not obligately required for the removal of scribble (scrib) mutant and similar polarity-deficient cells. Our experiments used identical stocks with which another group can detect the PTP10D requirement, and our results do not vary under several husbandry conditions including high and low protein food diets. Although we are unable to identify the source of the discrepant results, we suggest that the role of PTP10D in polarity-deficient cell elimination may not be absolute.

WASH activation controls endosomal recycling and EGFR and Hippo signaling during tumor-suppressive cell competition

Cell competition is a conserved homeostatic mechanism whereby epithelial cells eliminate neighbors with lower fitness. Cell communication at the interface of wild-type "winner" cells and polarity-deficient (scrib^-/-) "losers" is established through Sas-mediated Ptp10D activation in polarity-deficient cells. This tumor-suppressive cell competition restrains EGFR and Hippo signaling and enables Eiger-JNK mediated apoptosis in scrib^-/- clones. Here, we show that the activation state of the endosomal actin regulator WASH is a central node linking EGFR and Hippo signaling activation. The tyrosine kinase Btk29A and its substrate WASH are required downstream of Ptp10D for "loser" cell elimination. Constitutively active, phosphomimetic WASH is sufficient to induce both EGFR and Yki activation leading to overgrowth. On the mechanistic level we show that Ptp10D is recycled by the WASH/retromer complex, while EGFR is recycled by the WASH/retriever complex. Constitutive WASH activation selectively interferes with retromer function leading to Ptp10D mistargeting while promoting EGFR recycling and signaling activation. Phospho-WASH also activates aberrant Arp2/3 actin polymerization, leading to cytoskeletal imbalance, Yki activation and reduced apoptosis. Selective manipulation of WASH phosphorylation on sorting endosomes may restrict epithelial tumorous growth.

Game of clones: Battles in the field of carcinogenesis

Recent advances in bulk sequencing approaches as well as genomic decoding at the single-cell level have revealed surprisingly high somatic mutational burdens in normal tissues, as well as increased our understanding of the landscape of "field cancerization", that is, molecular and immune alterations in mutagen-exposed normal-appearing tissues that recapitulated those present in tumors. Charting the somatic mutational landscapes in normal tissues can have strong implications on our understanding of how tumors arise from mutagenized epithelium. Making sense of those mutations to understand the progression along the pathologic continuum of normal epithelia, preneoplasias, up to malignant tissues will help pave way for identification of ideal targets that can guide new strategies for preventing or eliminating cancers at their earliest stages of development. In this review, we will provide a brief history of field cancerization and its implications on understanding early stages of cancer pathogenesis and deviation from the pathologically "normal" state. The review will provide an overview of how mutations accumulating in normal tissues can lead to a patchwork of mutated cell clones that compete while maintaining an overall state of functional homeostasis. The review also explores the role of clonal competition in directing the fate of normal tissues and summarizes multiple mechanisms elicited in this phenomenon and which have been linked to cancer development. Finally, we highlight the importance of understanding mutations in normal tissues, as well as clonal competition dynamics (in both the epithelium and the microenvironment) and their significance in exploring new approaches to combatting cancer.

Obesity: a perfect storm for carcinogenesis

Obesity-related cancers account for 40% of the cancer cases observed in the USA and obesity is overtaking smoking as the most widespread modifiable risk factor for carcinogenesis. Here, we use the hallmarks of cancer framework to delineate how obesity might influence the carcinogenic hallmarks in somatic cells. We discuss the effects of obesity on (a) sustaining proliferative signaling; (b) evading growth suppressors; (c) resisting cell death; (d) enabling replicative immortality; (e) inducing angiogenesis; (f) activating invasion and metastasis; (g) reprogramming energy metabolism; and (h) avoiding immune destruction, together with its effects on genome instability and tumour-promoting inflammation. We present the current understanding and controversies in this evolving field, and highlight some areas in need of further cross-disciplinary focus. For instance, the relative importance of the many potentially causative obesity-related factors is unclear for each type of malignancy. Even within a single tumour type, it is currently unknown whether one obesity-related factor consistently plays a predominant role, or if this varies between patients or, even in a single patient with time. Clarifying how the hallmarks are affected by obesity may lead to novel prevention and treatment strategies for the increasingly obese population.

Insulin antibody as a biomarker to monitor the development of type 2 diabetes in county hospitals in China

Background

The significance of insulin antibody (IA) detection in type 2 diabetes mellitus (T2DM) has received scant attention from county hospitals in China. We aimed to introduce exogenous IA positive rate and its relative factors in T2DM treated with insulin in Xiangshan County of Ningbo City, analyzing the immunogenicity of different kinds of insulin.

Methods

Patients who were residents from the Danxi community and six towns (Dongchen, Xizhou, Maoyang, Sizhoutou, Juexi, and Qiangtou) in Xiangshan County and diagnosed with T2DM and treated with insulins at Xiangshan Hospital of TCM Medical and Health Group between August 2019 and June 2020 were identified. Those who met the eligibility criteria were included and assigned to the IA-positive or IA-negative group. The immunogenicity of different insulins was compared between the two groups.

Results

Among 992 patients, 781 were eligible for IA detection, and 40.2% of them were IA positive. Blood IA was closely associated with fasting and 2-h glucose, insulin, and C peptide levels and higher insulin dosage. Patients receiving basal insulin treatment showed significantly lower blood IA than those treated with mixed human insulin, premixed human insulins, rapid-acting analogs, or a combination of basal and rapid-acting analogs.

Cell competition and the regulative nature of early mammalian development

The mammalian embryo exhibits a remarkable plasticity that allows it to correct for the presence of aberrant cells, adjust its growth so that its size is in accordance with its developmental stage, or integrate cells of another species to form fully functional organs. Here, we will discuss the contribution that cell competition, a quality control that eliminates viable cells that are less fit than their neighbors, makes to this plasticity. We will do this by reviewing the roles that cell competition plays in the early mammalian embryo and how they contribute to ensure normal development of the embryo.

What we have learnt from Drosophila model organism: the coordination between insulin signaling pathway and tumor cells

Cancer development is related to a variety of signaling pathways which mediate various cellular processes including growth, survival, division and competition of cells, as well as cell-cell interaction. The insulin signaling pathway interacts with different pathways and plays a core role in the regulations of all these processes. In this study, we reviewed recent studies on the relationship between the insulin signaling pathway and tumors using the Drosophila melanogaster model. We found that on one hand, the insulin pathway is normally hyperactive in tumor cells, which promotes tumor growth, and on the other hand, tumor cells can suppress the growth of healthy tissues via inhibition of their insulin pathway. Moreover, systematic disruption in glucose homeostasis also facilitates cancer development by different mechanisms. The studies on how the insulin network regulates the behaviors of cancer cells may help to discover new therapeutic treatments for cancer.

Investigating local and systemic intestinal signalling in health and disease with Drosophila

Whole-body health relies on complex inter-organ signalling networks that enable organisms to adapt to environmental perturbations and to changes in tissue homeostasis. The intestine plays a major role as a signalling centre by producing local and systemic signals that are relayed to the body and that maintain intestinal and organismal homeostasis. Consequently, disruption of intestinal homeostasis and signalling are associated with systemic diseases and multi-organ dysfunction. In recent years, the fruit fly Drosophila melanogaster has emerged as a prime model organism to study tissue-intrinsic and systemic signalling networks of the adult intestine due to its genetic tractability and functional conservation with mammals. In this Review, we highlight Drosophila research that has contributed to our understanding of how the adult intestine interacts with its microenvironment and with distant organs. We discuss the implications of these findings for understanding intestinal and whole-body pathophysiology, and how future Drosophila studies might advance our knowledge of the complex interplay between the intestine and the rest of the body in health and disease.

Summary: We outline work in the fruit fly Drosophila melanogaster that has contributed knowledge on local and whole-body signalling coordinated by the adult intestine, and discuss its implications in intestinal pathophysiology and associated systemic dysfunction.

Tumour-host interactions through the lens of Drosophila

There is a large gap between the deep understanding of mechanisms driving tumour growth and the reasons why patients ultimately die of cancer. It is now appreciated that interactions between the tumour and surrounding non-tumour (sometimes referred to as host) cells play critical roles in mortality as well as tumour progression, but much remains unknown about the underlying molecular mechanisms, especially those that act beyond the tumour microenvironment. Drosophila has a track record of high-impact discoveries about cell-autonomous growth regulation, and is well suited to now probe mysteries of tumour - host interactions. Here, we review current knowledge about how fly tumours interact with microenvironmental stroma, circulating innate immune cells and distant organs to influence disease progression. We also discuss reciprocal regulation between tumours and host physiology, with a particular focus on paraneoplasias. The fly's simplicity along with the ability to study lethality directly provide an opportunity to shed new light on how cancer actually kills.

Metabolic Hormones Modulate Macrophage Inflammatory Responses

Simple Summary

Macrophages are a type of immune cell which play an important role in the development of cancer. Obesity increases the risk of cancer and obesity also causes disruption to the normal levels of hormones that are produced to coordinate metabolism. Recent research now shows that these metabolic hormones also play important roles in macrophage immune responses and so through macrophages, disrupted metabolic hormone levels may promote cancer. This review article aims to highlight and summarise these recent findings so that the scientific community may better understand how important this new area of research is, and how these findings can be capitalised on for future scientific studies.

Abstract

Macrophages are phagocytotic leukocytes that play an important role in the innate immune response and have established roles in metabolic diseases and cancer progression. Increased adiposity in obese individuals leads to dysregulation of many hormones including those whose functions are to coordinate metabolism. Recent evidence suggests additional roles of these metabolic hormones in modulating macrophage inflammatory responses. In this review, we highlight key metabolic hormones and summarise their influence on the inflammatory response of macrophages and consider how, in turn, these hormones may influence the development of different cancer types through the modulation of macrophage functions.

Cell competition, cooperation, and cancer

Complex multicellular organisms require quantitative and qualitative assessments on each of their constitutive cell types to ensure coordinated and cooperative behavior towards overall functional proficiency. Cell competition represents one of the operating arms of such quality control mechanisms and relies on fitness comparison among individual cells. However, what is exactly included in the fitness equation for each cell type is still uncertain. Evidence will be discussed to suggest that the ability of the cell to integrate and collaborate within the organismal community represents an integral part of the best fitness phenotype. Thus, under normal conditions, cell competition will select against the emergence of altered cells with disruptive behavior towards tissue integrity and/or tissue pattern formation. On the other hand, the winner phenotype prevailing as a result of cell competition does not entail, by itself, any degree of growth autonomy. While cell competition per se should not be considered as a biological driving force towards the emergence of the neoplastic phenotype, it is possible that the molecular machinery involved in the winner/loser interaction could be hijacked by evolving cancer cell populations.

Sequential oncogenic mutations influence cell competition

At the initial stage of carcinogenesis, newly emerging transformed cells are often eliminated from epithelial layers via cell competition with the surrounding normal cells. For instance, when surrounded by normal cells, oncoprotein RasV12-transformed cells are extruded into the apical lumen of epithelia. During cancer development, multiple oncogenic mutations accumulate within epithelial tissues. However, it remains elusive whether and how cell competition is also involved in this process. In this study, using a mammalian cell culture model system, we have investigated what happens upon the consecutive mutations of Ras and tumor suppressor protein Scribble. When Ras mutation occurs under the Scribble-knockdown background, apical extrusion of Scribble/Ras double-mutant cells is strongly diminished. In addition, at the boundary with Scribble/Ras cells, Scribble-knockdown cells frequently undergo apoptosis and are actively engulfed by the neighboring Scribble/Ras cells. The comparable apoptosis and engulfment phenotypes are also observed in Drosophila epithelial tissues between Scribble/Ras double-mutant and Scribble single-mutant cells. Furthermore, mitochondrial membrane potential is enhanced in Scribble/Ras cells, causing the increased mitochondrial reactive oxygen species (ROS). Suppression of mitochondrial membrane potential or ROS production diminishes apoptosis and engulfment of the surrounding Scribble-knockdown cells, indicating that mitochondrial metabolism plays a key role in the competitive interaction between double- and single-mutant cells. Moreover, mTOR (mechanistic target of rapamycin kinase) acts downstream of these processes. These results imply that sequential oncogenic mutations can profoundly influence cell competition, a transition from loser to winner. Further studies would open new avenues for cell competition-based cancer treatment, thereby blocking clonal expansion of more malignant populations within tumors.

Metabolic reprogramming in cancer: mechanistic insights from Drosophila

Cancer cells constantly reprogram their metabolism as the disease progresses. However, our understanding of the metabolic complexity of cancer remains incomplete. Extensive research in the fruit fly Drosophila has established numerous tumor models ranging from hyperplasia to neoplasia. These fly tumor models exhibit a broad range of metabolic profiles and varying nutrient sensitivity. Genetic studies show that fly tumors can use various alternative strategies, such as feedback circuits and nutrient-sensing machinery, to acquire and consolidate distinct metabolic profiles. These studies not only provide fresh insights into the causes and functional relevance of metabolic reprogramming but also identify metabolic vulnerabilities as potential targets for cancer therapy. Here, we review the conceptual advances in cancer metabolism derived from comparing and contrasting the metabolic profiles of fly tumor models, with a particular focus on the Warburg effect, mitochondrial metabolism, and the links between diet and cancer.

Summary: Recent research in fruit flies has demonstrated that tumors rewire their metabolism by using diverse strategies that involve feedback regulation, nutrient sensing, intercellular or even inter-organ interactions, yielding new molecules as potential cancer markers or drug targets.

Prognostic significance of preoperative haemoglobin A1c level in patients with lung adenocarcinoma

OBJECTIVES

We investigated the influence of the preoperative haemoglobin A1c (HbA1c) value on the prognosis and pathology of patients with lung adenocarcinoma who underwent surgery.

METHODS

We reviewed the medical records of 400 lung adenocarcinoma patients who underwent lobectomy with mediastinal lymph node dissection between 2009 and 2013 using a prospectively maintained database. We stratified 400 patients into 4 groups according to the preoperative HbA1c value as follows: HbA1c ≤ 5.9 (n = 296), 6.0 ≤ HbA1c ≤ 6.9 (n = 70), 7.0 ≤ HbA1c ≤ 7.9 (n = 21) and HbA1c ≥ 8.0 (n = 12). We compared the recurrence-free survival and overall survival (OS) among these 4 groups. Univariate and multivariate analyses were performed to identify the risk factors for recurrence.

RESULTS

The median follow-up period was 61.2 months. On comparing the recurrence-free survival and OS rates among these 4 groups, we found that these rates among patients in the HbA1c ≥ 8.0 group were significantly poorer compared with the other 3 groups (5-year recurrence-free survival: HbA1c ≤ 5.9, 70.4%; 6.0 ≤ HbA1c ≤ 6.9, 69.7%; 7.0 ≤ HbA1c ≤ 7.9, 70.7%; ≥8.0 HbA1c, 18.8%; P = 0.002; and 5-year OS: HbA1c ≤ 5.9, 88.7%; 6.0 ≤ HbA1c ≤ 6.9, 80.6%; 7.0 ≤ HbA1c ≤ 7.9, 90.2%; ≥8.0 HbA1c, 66.7%; P = 0.046). Patients in the HbA1c ≥ 8.0 group had significantly more tumours with vascular invasion (P = 0.041) and experienced distant metastasis significantly more often (P = 0.028) than those with other values. A multivariate analysis revealed that preoperative HbA1c ≥ 8.0 [hazard ratio (HR) 2.33; P = 0.026] and lymph node metastasis (HR 3.94; P < 0.001) were significant independent prognostic factors for recurrence.

CONCLUSIONS

Our results revealed that preoperative HbA1c ≥ 8.0 is associated to poor prognosis due to the occurrence of distant metastasis and we should carefully follow these patients after surgery.

CLINICAL REGISTRATION NUMBER

Hyogo Cancer Center, G-57.

Hyperinsulinemia in Obesity, Inflammation, and Cancer

The relative insufficiency of insulin secretion and/or insulin action causes diabetes. However, obesity and type 2 diabetes mellitus can be associated with an absolute increase in circulating insulin, a state known as hyperinsulinemia. Studies are beginning to elucidate the cause-effect relationships between hyperinsulinemia and numerous consequences of metabolic dysfunctions. Here, we review recent evidence demonstrating that hyperinsulinemia may play a role in inflammation, aging and development of cancers. In this review, we will focus on the consequences and mechanisms of excess insulin production and action, placing recent findings that have challenged dogma in the context of the existing body of literature. Where relevant, we elaborate on the role of specific signal transduction components in the actions of insulin and consequences of chronic hyperinsulinemia. By discussing the involvement of hyperinsulinemia in various metabolic and other chronic diseases, we may identify more effective therapeutics or lifestyle interventions for preventing or treating obesity, diabetes and cancer. We also seek to identify pertinent questions that are ripe for future investigation.

Application of CRISPR screens to investigate mammalian cell competition

Cell competition is defined as the context-dependent elimination of cells that is mediated by intercellular communication, such as paracrine or contact-dependent cell signaling, and/or mechanical stresses. It is considered to be a quality control mechanism that facilitates the removal of suboptimal cells from both adult and embryonic tissues. Cell competition, however, can also be hijacked by transformed cells to acquire a 'super-competitor' status and outcompete the normal epithelium to establish a precancerous field. To date, many genetic drivers of cell competition have been identified predominately through studies in Drosophila. Especially during the last couple of years, ethylmethanesulfonate-based genetic screens have been instrumental to our understanding of the molecular regulators behind some of the most common competition mechanisms in Drosophila, namely competition due to impaired ribosomal function (or anabolism) and mechanical sensitivity. Despite recent findings in Drosophila and in mammalian models of cell competition, the drivers of mammalian cell competition remain largely elusive. Since the discovery of CRISPR/Cas9, its use in functional genomics has been indispensable to uncover novel cancer vulnerabilities. We envision that CRISPR/Cas9 screens will enable systematic, genome-scale probing of mammalian cell competition to discover novel mutations that not only trigger cell competition but also identify novel molecular components that are essential for the recognition and elimination of less fit cells. In this review, we summarize recent contributions that further our understanding of the molecular mechanisms of cell competition by genetic screening in Drosophila, and provide our perspective on how similar and novel screening strategies made possible by whole-genome CRISPR/Cas9 screening can advance our understanding of mammalian cell competition in the future.

Genetic manipulation of insulin/insulin-like growth factor signaling pathway activity has sex-biased effects on Drosophila body size

In Drosophila raised in nutrient-rich conditions, female body size is approximately 30% larger than male body size due to an increased rate of growth and differential weight loss during the larval period. While the mechanisms that control this sex difference in body size remain incompletely understood, recent studies suggest that the insulin/insulin-like growth factor signaling pathway (IIS) plays a role in the sex-specific regulation of processes that influence body size during development. In larvae, IIS activity differs between the sexes, and there is evidence of sex-specific regulation of IIS ligands. Yet, we lack knowledge of how changes to IIS activity impact body size in each sex, as the majority of studies on IIS and body size use single- or mixed-sex groups of larvae and/or adult flies. The goal of our current study was to clarify the body size requirement for IIS activity in each sex. To achieve this goal, we used established genetic approaches to enhance, or inhibit, IIS activity, and quantified pupal size in males and females. Overall, genotypes that inhibited IIS activity caused a female-biased decrease in body size, whereas genotypes that augmented IIS activity caused a male-specific increase in body size. These data extend our current understanding of body size regulation by showing that most changes to IIS pathway activity have sex-biased effects, and highlights the importance of analyzing body size data according to sex.

Metabolic regulation of cell competition

Cell Competition is a selective process by which viable cells are eliminated from developing or adult tissues by interactions with their neighbors. In many cases, the eliminated cells (losers) display reduced fitness, yet they would be able to sustain tissue growth or maintenance in a homotypic environment, and are only eliminated when confronted with surrounding wild type cells (winners). In addition, cells with oncogenic mutations that do not show reduced fitness can also be eliminated from tissues when surrounded by wild type cells. Depending on the context, transformed cells can also become supercompetitors and eliminate surrounding wild type cells, thereby promoting tumor formation. Several factors have been shown to play essential roles in Cell Competition, including genes relevant in developmental growth, tumor formation and epithelial apico-basal polarity. Recent discoveries, however, suggest that energy metabolism plays a central role in very different models of cell competition. Here we review the involvement of mitochondrial dynamics and metabolism, autophagy and nutritional status in cell competition and discuss the possible implications of this emerging field.

Diabetes, Antidiabetic Medications and Cancer Risk in Type 2 Diabetes: Focus on SGLT-2 Inhibitors

In the last decade, cancer became the leading cause of death in the population under 65 in the European Union. Diabetes is also considered as a factor increasing risk of cancer incidence and mortality. Type 2 diabetes is frequently associated with being overweight and obese, which also plays a role in malignancy. Among biological mechanisms linking diabetes and obesity with cancer hyperglycemia, hyperinsulinemia, insulin resistance, increased levels of growth factors, steroid and peptide hormones, oxidative stress and increased activity of pro-inflammatory cytokines are listed. Antidiabetic medications can modulate cancer risk through directly impacting metabolism of cancer cells as well as indirectly through impact on risk factors of malignancy. Some of them are considered beneficial (metformin and thiazolidinedions—with the exception of bladder cancer); on the other hand, excess of exogenous insulin may be potentially harmful, while other medications seem to have neutral impact on cancer risk. Inhibitors of the sodium-glucose cotransporter-2 (SGLT-2) are increasingly used in the treatment of type 2 diabetes. However, their association with cancer risk is unclear. The aim of this review was to analyze the anticancer potential of this class of drugs, as well as risks of site-specific malignancies associated with their use.

Tiny Drosophila makes giant strides in cancer research

Cancer burden has been increasing worldwide, making cancer the second leading cause of death in the world. Over the past decades, various experimental models have provided important insights into the nature of cancer. Among them, the fruit fly Drosophila as a whole-animal toolkit has made a decisive contribution to our understanding of fundamental mechanisms of cancer development including loss of cell polarity. In recent years, scalable Drosophila platforms have proven useful also in developing anti-cancer regimens that are effective not only in mammalian models but also in patients. Here, we review studies using Drosophila as a tool to advance cancer study by complementing other traditional research systems.

Systemic Regulation of Local Cell Competition

Somatic scribble mutant cells are selectively eliminated from the growing Drosophila tissue through cell competition, a tumor-suppressing mechanism that ensures tissue integrity. In this issue of Developmental Cell, Sanaki et al. demonstrate that organismal hyperinsulinemia promotes tumorigenesis by abrogating local cell competition.

Can natural selection and druggable targets synergize? Of nutrient scarcity, cancer, and the evolution of cooperation

Since the dawn of molecular biology, cancer therapy has focused on druggable targets. Despite some remarkable successes, cell-level evolution remains a potent antagonist to this approach. We suggest that a deeper understanding of the breakdown of cooperation can synergize the evolutionary and druggable-targets approaches. Complexity requires cooperation, whether between cells of different species (symbiosis) or between cells of the same organism (multicellularity). Both forms of cooperation may be associated with nutrient scarcity, which in turn may be associated with a chemiosmotic metabolism. A variety of examples from modern organisms supports these generalities. Indeed, mammalian cancers-unicellular, glycolytic, and fast-replicating-parallel these examples. Nutrient scarcity, chemiosmosis, and associated signaling may favor cooperation, while under conditions of nutrient abundance a fermentative metabolism may signal the breakdown of cooperation. Manipulating this metabolic milieu may potentiate the effects of targeted therapeutics. Specific opportunities are discussed in this regard, including avicins, a novel plant product.

Emerging mechanisms of cell competition

The growth and survival of cells within tissues can be affected by 'cell competition' between different cell clones. This phenomenon was initially recognized between wild-type cells and cells with mutations in ribosomal protein (Rp) genes in Drosophila melanogaster. However, competition also affects D. melanogaster cells with mutations in epithelial polarity genes, and wild-type cells exposed to 'super-competitor' cells with mutation in the Salvador-Warts-Hippo tumour suppressor pathway or expressing elevated levels of Myc. More recently, cell competition and super-competition were recognized in mammalian development, organ homeostasis and cancer. Genetic and cell biological studies have revealed that mechanisms underlying cell competition include the molecular recognition of 'different' cells, signalling imbalances between distinct cell populations and the mechanical consequences of differential growth rates; these mechanisms may also involve innate immune proteins, p53 and changes in translation.

Mechanism of tumor-suppressive cell competition in flies

Oncogenic mutations often trigger antitumor cellular response such as induction of apoptosis or cellular senescence. Studies in the last decade have identified the presence of the third guardian against mutation‐induced tumorigenesis, namely “cell competition.” Cell competition is a context‐dependent cell elimination whereby cells with higher fitness eliminate neighboring cells with lower fitness by inducing cell death. While oncogene‐induced apoptosis or oncogene‐induced senescence acts as a cell‐autonomous tumor suppressor, cell competition protects the tissue from tumorigenesis via cell‐cell communication. For instance, in Drosophila epithelium, oncogenic cells with cell polarity mutations overproliferate and develop into tumors on their own but are eliminated from the tissue when surrounded by wild‐type cells. Genetic studies in flies have unraveled that such tumor‐suppressive cell competition is regulated by at least three mechanisms: direct cell‐cell interaction between polarity‐deficient cells and wild‐type cells, secreted factors from epithelial cells, and systemic factors from distant organs. Molecular manipulation of tumor‐suppressive cell competition could provide a novel therapeutic strategy against human cancers.

Cancer cells harness insulin for performance enhancement

Hyperinsulinemia and insulin receptor signaling allow cancer cells to evade cell competition.