A personalized platform identifies trametinib plus zoledronate for a patient with KRAS-mutant metastatic colorectal cancer

[Drosophila as a model to study cancer biology]

The rising global incidence of cancer makes it the second leading cause of death worldwide. Over the past decades, significant progress has been made in both basic knowledge and the discovery of new therapeutic approaches. However, the complexity of mechanisms related to tumor development requires the use of sophisticated and adapted research tools. Among these, the fruitfly Drosophila melanogaster represents a powerful genetic model with numerous practical and conceptual advantages. Indeed, the conservation of genes implicated in cancer between this insect and mammals places Drosophila as a crucial genetic tool for understanding the fundamental mechanisms governing tumorigenesis and identifying new therapeutic targets. This review aims to describe this original model and demonstrate its relevance for studying cancer biology.

Functional exploration of copy number alterations in a Drosophila model of triple-negative breast cancer

Accounting for 10-20% of breast cancer cases, triple-negative breast cancer (TNBC) is associated with a disproportionate number of breast cancer deaths. One challenge in studying TNBC is its genomic profile: with the exception of TP53 loss, most breast cancer tumors are characterized by a high number of copy number alterations (CNAs), making modeling the disease in whole animals challenging. We computationally analyzed 186 CNA regions previously identified in breast cancer tumors to rank genes within each region by likelihood of acting as a tumor driver. We then used a Drosophila p53-Myc TNBC model to identify 48 genes as functional drivers. To demonstrate the utility of this functional database, we established six 3-hit models; altering candidate genes led to increased aspects of transformation as well as resistance to the chemotherapeutic drug fluorouracil. Our work provides a functional database of CNA-associated TNBC drivers, and a template for an integrated computational/whole-animal approach to identify functional drivers of transformation and drug resistance within CNAs in other tumor types.

Cholesterol Dietary Intake and Tumor Cell Homeostasis Drive Early Epithelial Tumorigenesis: A Potential Modelization of Early Prostate Tumorigenesis

Epidemiological studies point to cholesterol as a possible key factor for both prostate cancer incidence and progression. It could represent a targetable metabolite as the most aggressive tumors also appear to be sensitive to therapies designed to decrease hypercholesterolemia, such as statins. However, it remains unknown whether and how cholesterol, through its dietary uptake and its metabolism, could be important for early tumorigenesis. Oncogene clonal induction in the Drosophila melanogaster accessory gland allows us to reproduce tumorigenesis from initiation to early progression, where tumor cells undergo basal extrusion to form extra-epithelial tumors. Here we show that these tumors accumulate lipids, and especially esterified cholesterol, as in human late carcinogenesis. Interestingly, a high-cholesterol diet has a limited effect on accessory gland tumorigenesis. On the contrary, cell-specific downregulation of cholesterol uptake, intracellular transport, or metabolic response impairs the formation of such tumors. Furthermore, in this context, a high-cholesterol diet suppresses this impairment. Interestingly, expression data from primary prostate cancer tissues indicate an early signature of redirection from cholesterol de novo synthesis to uptake. Taken together, these results reveal that during early tumorigenesis, tumor cells strongly increase their uptake and use of dietary cholesterol to specifically promote the step of basal extrusion. Hence, these results suggest the mechanism by which a reduction in dietary cholesterol could lower the risk and slow down the progression of prostate cancer.

Vitamin B6 deficiency cooperates with oncogenic Ras to induce malignant tumors in Drosophila

Vitamin B6 is a water-soluble vitamin which possesses antioxidant properties. Its catalytically active form, pyridoxal 5'-phosphate (PLP), is a crucial cofactor for DNA and amino acid metabolism. The inverse correlation between vitamin B6 and cancer risk has been observed in several studies, although dietary vitamin B6 intake sometimes failed to confirm this association. However, the molecular link between vitamin B6 and cancer remains elusive. Previous work has shown that vitamin B6 deficiency causes chromosome aberrations (CABs) in Drosophila and human cells, suggesting that genome instability may correlate the lack of this vitamin to cancer. Here we provide evidence in support of this hypothesis. Firstly, we show that PLP deficiency, induced by the PLP antagonists 4-deoxypyridoxine (4DP) or ginkgotoxin (GT), promoted tumorigenesis in eye larval discs transforming benign RasV12 tumors into aggressive forms. In contrast, PLP supplementation reduced the development of tumors. We also show that low PLP levels, induced by 4DP or by silencing the sgllPNPO gene involved in PLP biosynthesis, worsened the tumor phenotype in another Drosophila cancer model generated by concomitantly activating RasV12 and downregulating Discs-large (Dlg) gene. Moreover, we found that RasV12 eye discs from larvae reared on 4DP displayed CABs, reactive oxygen species (ROS) and low catalytic activity of serine hydroxymethyltransferase (SHMT), a PLP-dependent enzyme involved in thymidylate (dTMP) biosynthesis, in turn required for DNA replication and repair. Feeding RasV12 4DP-fed larvae with PLP or ascorbic acid (AA) plus dTMP, rescued both CABs and tumors. The same effect was produced by overexpressing catalase in RasV12 DlgRNAi 4DP-fed larvae, thus allowing to establish a relationship between PLP deficiency, CABs, and cancer. Overall, our data provide the first in vivo demonstration that PLP deficiency can impact on cancer by increasing genome instability, which is in turn mediated by ROS and reduced dTMP levels.

CircFBXW4 Suppresses Colorectal Cancer Progression by Regulating the MiR-338-5p/SLC5A7 Axis

Dysregulated circular RNAs (circRNAs) contribute to tumourigenesis and cancer progression. However, the expression patterns and biological functions of circRNAs in colorectal cancer (CRC) remain elusive. Here, RNA sequencing and bioinformatics analyses are applied to screen for aberrantly expressed circRNAs. The expression of circFBXW4 in CRC tissues and cell lines is determined by quantitative real-time PCR. A series of in vitro and in vivo biological function assays are implemented to assess the functions of circFBXW4. The regulatory mechanisms linking circFBXW4, miR-338-5p, and SLC5A7 are explored by western blotting, dual luciferase reporter assays, and RNA pull-down assays. CircFBXW4 is dramatically downregulated in CRC tissues and cell lines. circFBXW4 downregulation is clearly correlated with malignant features and patient overall survival in CRC. Functionally, ectopic expression of circFBXW4 strikingly impairs the proliferation, migration, and invasion capacities of CRC cells in vitro and in vivo, whereas circFBXW4 knockdown has the opposite effects. Mechanistically, circFBXW4 competitively binds to miR-338-5p and prevents it from interacting with and repressing its target SLC5A7, thus suppressing the progression of CRC. This study reveals the specific critical role of circFBXW4 in inhibiting CRC progression via the miR-338-5p/SLC5A7 axis and provides an additional target for eradicating CRC.

Senescent cells and macrophages cooperate through a multi-kinase signaling network to promote intestinal transformation in Drosophila

Cellular senescence is a conserved biological process that plays a crucial and context-dependent role in cancer. The highly heterogeneous and dynamic nature of senescent cells and their small numbers in tissues make in vivo mechanistic studies of senescence challenging. As a result, how multiple senescence-inducing signals are integrated in vivo to drive senescence in only a small number of cells is unclear. Here, we identify cells that exhibit multiple features of senescence in a Drosophila model of intestinal transformation, which emerge in response to concurrent activation of AKT, JNK, and DNA damage signaling within transformed tissue. Eliminating senescent cells, genetically or by treatment with senolytic compounds, reduces overgrowth and improves survival. We find that senescent cells promote tumorigenesis by recruiting Drosophila macrophages to the transformed tissue, which results in non-autonomous activation of JNK signaling. These findings identify senescent cell-macrophage interactions as an important driver of epithelial transformation.

Colon Cancer Cells Evade Drug Action by Enhancing Drug Metabolism

Colorectal cancer (CRC) is the second most deadly cancer worldwide. One key reason is the failure of therapies that target RAS proteins, which represent approximately 40% of CRC cases. Despite the recent discovery of multiple alternative signalling pathways that contribute to resistance, durable therapies remain an unmet need. Here, we use liquid chromatography/mass spectrometry (LC/MS) analyses on Drosophila CRC tumour models to identify multiple metabolites in the glucuronidation pathway-a toxin clearance pathway-as upregulated in trametinib-resistant RAS/APC/P53 ("RAP") tumours compared to trametinib-sensitive RASG12V tumours. Elevating glucuronidation was sufficient to direct trametinib resistance in RASG12V animals while, conversely, inhibiting different steps along the glucuronidation pathway strongly reversed RAP resistance to trametinib. For example, blocking an initial HDAC1-mediated deacetylation step with the FDA-approved drug vorinostat strongly suppressed trametinib resistance in Drosophila RAP tumours. We provide functional evidence that pairing oncogenic RAS with hyperactive WNT activity strongly elevates PI3K/AKT/GLUT signalling, which in turn directs elevated glucose and subsequent glucuronidation. Finally, we show that this mechanism of trametinib resistance is conserved in an KRAS/APC/TP53 mouse CRC tumour organoid model. Our observations demonstrate a key mechanism by which oncogenic RAS/WNT activity promotes increased drug clearance in CRC. The majority of targeted therapies are glucuronidated, and our results provide a specific path towards abrogating this resistance in clinical trials.

Disruptions in cell fate decisions and transformed enteroendocrine cells drive intestinal tumorigenesis in Drosophila

Most epithelial tissues are maintained by stem cells that produce the different cell lineages required for proper tissue function. Constant communication between different cell types ensures precise regulation of stem cell behavior and cell fate decisions. These cell-cell interactions are often disrupted during tumorigenesis, but mechanisms by which they are co-opted to support tumor growth in different genetic contexts are poorly understood. Here, we introduce PromoterSwitch, a genetic platform we established to generate large, transformed clones derived from individual adult Drosophila intestinal stem/progenitor cells. We show that cancer-driving genetic alterations representing common colon tumor genome landscapes disrupt cell fate decisions within transformed tissue and result in the emergence of abnormal cell fates. We also show that transformed enteroendocrine cells, a differentiated, hormone-secreting cell lineage, support tumor growth by regulating intestinal stem cell proliferation through multiple genotype-dependent mechanisms, which represent potential vulnerabilities that could be exploited for therapy.

Drug Repurposing Analysis for Colorectal Cancer through Network Medicine Framework: Novel Candidate Drugs and Small Molecules

This study aimed to reveal the drug-repurposing candidates for colorectal cancer (CRC) via drug-repurposing methods and network biology approaches. A novel, differentially co-expressed, highly interconnected, and co-regulated prognostic gene module was identified for CRC. Based on the gene module, polyethylene glycol (PEG), gallic acid, pyrazole, cordycepin, phenothiazine, pantoprazole, cysteamine, indisulam, valinomycin, trametinib, BRD-K81473043, AZD8055, dovitinib, BRD-A17065207, and tyrphostin AG1478 presented as drugs and small molecule candidates previously studied in the CRC. Lornoxicam, suxamethonium, oprelvekin, sirukumab, levetiracetam, sulpiride, NVP-TAE684, AS605240, 480743.cdx, HDAC6 inhibitor ISOX, BRD-K03829970, and L-6307 are proposed as novel drugs and small molecule candidates for CRC.

Intestinal stem cells and their niches in homeostasis and disease

Tissues such as the intestine harbor stem cells that have remarkable functional plasticity in response to a dynamic environment. To adapt to the environment, stem cells constantly receive information from their surrounding microenvironment (also called the 'niche') that instructs them how to adapt to changes. The Drosophila midgut shows morphological and functional similarities to the mammalian small intestine and has been a useful model system to study signaling events in stem cells and tissue homeostasis. In this review, we summarize the current understanding of the Drosophila midgut regarding how stem cells communicate with microenvironmental niches including enteroblasts, enterocytes, enteroendocrine cells and visceral muscles to coordinate tissue regeneration and homeostasis. In addition, distant cells such as hemocytes or tracheal cells have been shown to interact with stem cells and influence the development of intestinal diseases. We discuss the contribution of stem cell niches in driving or counteracting disease progression, and review conceptual advances derived from the Drosophila intestine as a model for stem cell biology.

Drosophila Screening Identifies Dual Inhibition of MEK and AURKB as an Effective Therapy for Pancreatic Ductal Adenocarcinoma

Significant progress has been made in understanding the pathogenesis of pancreatic ductal adenocarcinoma (PDAC) by generating and using murine models. To accelerate drug discovery by identifying novel therapeutic targets on a systemic level, here we generated a Drosophila model mimicking the genetic signature in PDAC (KRAS, TP53, CDKN2A, and SMAD4 alterations), which is associated with the worst prognosis in patients. The '4-hit' flies displayed epithelial transformation and decreased survival. Comprehensive genetic screening of their entire kinome revealed kinases including MEK and AURKB as therapeutic targets. Consistently, a combination of the MEK inhibitor trametinib and the AURKB inhibitor BI-831266 suppressed the growth of human PDAC xenografts in mice. In patients with PDAC, the activity of AURKB was associated with poor prognosis. This fly-based platform provides an efficient whole-body approach that complements current methods for identifying therapeutic targets in PDAC.

SIGNIFICANCE

Development of a Drosophila model mimicking genetic alterations in human pancreatic ductal adenocarcinoma provides a tool for genetic screening that identifies MEK and AURKB inhibition as a potential treatment strategy.

The Comet Assay in Drosophila: A Tool to Study Interactions between DNA Repair Systems in DNA Damage Responses In Vivo and Ex Vivo

The comet assay in Drosophila has been used in the last few years to study DNA damage responses (DDR) in different repair-mutant strains and to compare them to analyze DNA repair. We have used this approach to study interactions between DNA repair pathways in vivo. Additionally, we have implemented an ex vivo comet assay, in which nucleoids from treated and untreated cells were incubated ex vivo with cell-free protein extracts from individuals with distinct repair capacities. Four strains were used: wild-type OregonK (OK), nucleotide excision repair mutant mus201, dmPolQ protein mutant mus308, and the double mutant mus201;mus308. Methyl methanesulfonate (MMS) was used as a genotoxic agent. Both approaches were performed with neuroblasts from third-instar larvae; they detected the effects of the NER and dmPolQ pathways on the DDR to MMS and that they act additively in this response. Additionally, the ex vivo approach quantified that mus201, mus308, and the double mutant mus201;mus308 strains presented, respectively, 21.5%, 52.9%, and 14.8% of OK strain activity over MMS-induced damage. Considering the homology between mammals and Drosophila in repair pathways, the detected additive effect might be extrapolated even to humans, demonstrating that Drosophila might be an excellent model to study interactions between repair pathways.

Drosophila innate immunity suppresses the survival of xenografted mammalian tumor cells

Patient-derived xenograft (PDX) is an emerging tool established in immunodeficient vertebrate models to assess individualized treatments for cancer patients. Current xenograft models are deficient in adaptive immune systems. However, the precise role of the innate immunity in the xenograft models is unknown. With conserved signaling pathways and established genetic tools, Drosophila has contributed to the understanding of the mechanism of tumor growth as well as tumor-host interactions for decades, making it a promising candidate model for studying whether or not the hosts' innate immunity can accommodate transplanted human tumor cells. Here we show initial observations that assess the behavior and impact of several human tumor cell lines when transplanted into Drosophila. We found that some injected cell lines persisted for a longer duration and reduced hosts' lifespan. In particular, the human lung cancer cell line A549 were observed adjacent to the fly host tissues. We examined two factors that affect the survivability of cancer cells: (1) the optimal temperature of each cell line and (2) the innate immunity of Drosophila hosts. Especially, transplanted human tumor cells survived longer in immunodeficient flies, suggesting that the host innate immune system impedes the growth of xenografted cells. Our attempts for xenografting fly models thus provide necessary steps to overcome for establishing PDX cancer models using invertebrates.

A polycistronic transgene design for combinatorial genetic perturbations from a single transcript in Drosophila

Experimental models that capture the genetic complexity of human disease and allow mechanistic explorations of the underlying cell, tissue, and organ interactions are crucial to furthering our understanding of disease biology. Such models require combinatorial manipulations of multiple genes, often in more than one tissue at once. The ability to perform complex genetic manipulations in vivo is a key strength of Drosophila, where many tools for sophisticated and orthogonal genetic perturbations exist. However, combining the large number of transgenes required to establish more representative disease models and conducting mechanistic studies in these already complex genetic backgrounds is challenging. Here we present a design that pushes the limits of Drosophila genetics by allowing targeted combinatorial ectopic expression and knockdown of multiple genes from a single inducible transgene. The polycistronic transcript encoded by this transgene includes a synthetic short hairpin cluster cloned within an intron placed at the 5' end of the transcript, followed by two protein-coding sequences separated by the T2A sequence that mediates ribosome skipping. This technology is particularly useful for modeling genetically complex diseases like cancer, which typically involve concurrent activation of multiple oncogenes and loss of multiple tumor suppressors. Furthermore, consolidating multiple genetic perturbations into a single transgene further streamlines the ability to perform combinatorial genetic manipulations and makes it readily adaptable to a broad palette of transgenic systems. This flexible design for combinatorial genetic perturbations will also be a valuable tool for functionally exploring multigenic gene signatures identified from omics studies of human disease and creating humanized Drosophila models to characterize disease-associated variants in human genes. It can also be adapted for studying biological processes underlying normal tissue homeostasis and development that require simultaneous manipulation of many genes.

Senescent cells and macrophages cooperate through a multi-kinase signaling network to promote intestinal transformation in Drosophila

Cellular senescence is a conserved biological process essential for embryonic development, tissue remodeling, repair, and a key regulator of aging. Senescence also plays a crucial role in cancer, though this role can be tumor-suppressive or tumor-promoting, depending on the genetic context and the microenvironment. The highly heterogeneous, dynamic, and context-dependent nature of senescence-associated features and the relatively small numbers of senescent cells in tissues makes in vivo mechanistic studies of senescence challenging. As a result, which senescence-associated features are observed in which disease contexts and how they contribute to disease phenotypes remain largely unknown. Similarly, the specific mechanisms by which various senescence-inducing signals are integrated in vivo to induce senescence and why some cells become senescent while their immediate neighbors do not are unclear. Here, we identify a small number of cells that exhibit multiple features of senescence in a genetically complex model of intestinal transformation we recently established in the developing Drosophila larval hindgut epithelium. We demonstrate that these cells emerge in response to concurrent activation of AKT, JNK, and DNA damage response pathways within transformed tissue. Eliminating senescent cells, genetically or by treatment with senolytic compounds, reduces overgrowth and improves survival. We find that this tumor-promoting role is mediated by Drosophila macrophages recruited to the transformed tissue by senescent cells, which results in non-autonomous activation of JNK signaling within the transformed epithelium. These findings emphasize complex cell-cell interactions underlying epithelial transformation and identify senescent cell-macrophage interactions as a potential druggable node in cancer.

A targeted genetic modifier screen in Drosophila uncovers vulnerabilities in a genetically complex model of colon cancer

Received on 16 January 2023; accepted on 21 February 2023Kinases are key regulators of cellular signal transduction pathways. Many diseases, including cancer, are associated with global alterations in protein phosphorylation networks. As a result, kinases are frequent targets of drug discovery efforts. However, target identification and assessment, a critical step in targeted drug discovery that involves identifying essential genetic mediators of disease phenotypes, can be challenging in complex, heterogeneous diseases like cancer, where multiple concurrent genomic alterations are common. Drosophila is a particularly useful genetic model system to identify novel regulators of biological processes through unbiased genetic screens. Here, we report 2 classic genetic modifier screens focusing on the Drosophila kinome to identify kinase regulators in 2 different backgrounds: KRAS TP53 PTEN APC, a multigenic cancer model that targets 4 genes recurrently mutated in human colon tumors and KRAS alone, a simpler model that targets one of the most frequently altered pathways in cancer. These screens identified hits unique to each model and one shared by both, emphasizing the importance of capturing the genetic complexity of human tumor genome landscapes in experimental models. Our follow-up analysis of 2 hits from the KRAS-only screen suggests that classical genetic modifier screens in heterozygous mutant backgrounds that result in a modest, nonlethal reduction in candidate gene activity in the context of a whole animal-a key goal of systemic drug treatment-may be a particularly useful approach to identify the most rate-limiting genetic vulnerabilities in disease models as ideal candidate drug targets.

Integrated regulation of dopaminergic and epigenetic effectors of neuroprotection in Parkinson's disease models

Whole-exome sequencing of Parkinson's disease (PD) patient DNA identified single-nucleotide polymorphisms (SNPs) in the tyrosine nonreceptor kinase-2 (TNK2) gene. Although this kinase had a previously demonstrated activity in preventing the endocytosis of the dopamine reuptake transporter (DAT), a causal role for TNK2-associated dysfunction in PD remains unresolved. We postulated the dopaminergic neurodegeneration resulting from patient-associated variants in TNK2 were a consequence of aberrant or prolonged TNK2 overactivity, the latter being a failure in TNK2 degradation by an E3 ubiquitin ligase, neuronal precursor cell-expressed developmentally down-regulated-4 (NEDD4). Interestingly, systemic RNA interference protein-3 (SID-3) is the sole TNK2 ortholog in the nematode Caenorhabditis elegans, where it is an established effector of epigenetic gene silencing mediated through the dsRNA-transporter, SID-1. We hypothesized that TNK2/SID-3 represents a node of integrated dopaminergic and epigenetic signaling essential to neuronal homeostasis. Use of a TNK2 inhibitor (AIM-100) or a NEDD4 activator [N-aryl benzimidazole 2 (NAB2)] in bioassays for either dopamine- or dsRNA-uptake into worm dopaminergic neurons revealed that sid-3 mutants displayed robust neuroprotection from 6-hydroxydopamine (6-OHDA) exposures, as did AIM-100 or NAB2-treated wild-type animals. Furthermore, NEDD4 activation by NAB2 in rat primary neurons correlated to a reduction in TNK2 levels and the attenuation of 6-OHDA neurotoxicity. CRISPR-edited nematodes engineered to endogenously express SID-3 variants analogous to TNK2 PD-associated SNPs exhibited enhanced susceptibility to dopaminergic neurodegeneration and circumvented the RNAi resistance characteristic of SID-3 dysfunction. This research exemplifies a molecular etiology for PD whereby dopaminergic and epigenetic signaling are coordinately regulated to confer susceptibility or resilience to neurodegeneration.

High-throughput screening of caterpillars as a platform to study host-microbe interactions and enteric immunity

Mammalian models of human disease are expensive and subject to ethical restrictions. Here, we present an independent platform for high-throughput screening, using larvae of the tobacco hornworm Manduca sexta, combining diagnostic imaging modalities for a comprehensive characterization of aberrant phenotypes. For validation, we use bacterial/chemical-induced gut inflammation to generate a colitis-like phenotype and identify significant alterations in morphology, tissue properties, and intermediary metabolism, which aggravate with disease progression and can be rescued by antimicrobial treatment. In independent experiments, activation of the highly conserved NADPH oxidase DUOX, a key mediator of gut inflammation, leads to similar, dose-dependent alterations, which can be attenuated by pharmacological interventions. Furthermore, the developed platform could differentiate pathogens from mutualistic gastrointestinal bacteria broadening the scope of applications also to microbiomics and host-pathogen interactions. Overall, larvae-based screening can complement mammals in preclinical studies to explore innate immunity and host-pathogen interactions, thus representing a substantial contribution to improve mammalian welfare.

Drosophila as a toolkit to tackle cancer and its metabolism

Cancer is one of the most severe health problems worldwide accounting for the second leading cause of death. Studies have indicated that cancers utilize different metabolic systems as compared with normal cells to produce extra energy and substances required for their survival, which contributes to tumor formation and progression. Recently, the fruit fly Drosophila has been attracting significant attention as a whole-body model for elucidating the cancer mechanisms including metabolism. This tiny organism offers a valuable toolkit with various advantages such as high genetic conservation and similar drug response to mammals. In this review, we introduce flies modeling for cancer patient genotypes which have pinpointed novel therapeutic targets and drug candidates in the salivary gland, thyroid, colon, lung, and brain. Furthermore, we introduce fly models for metabolic diseases such as diabetes mellitus, obesity, and cachexia. Diabetes mellitus and obesity are widely acknowledged risk factors for cancer, while cachexia is a cancer-related metabolic condition. In addition, we specifically focus on two cancer metabolic alterations: the Warburg effect and redox metabolism. Indeed, flies proved useful to reveal the relationship between these metabolic changes and cancer. Such accumulating achievements indicate that Drosophila offers an efficient platform to clarify the mechanisms of cancer as a systemic disease.

Drosophila melanogaster: A platform for anticancer drug discovery and personalized therapies

Cancer is a complex disease whereby multiple genetic aberrations, epigenetic modifications, metabolic reprogramming, and the microenvironment contribute to the development of a tumor. In the traditional anticancer drug discovery pipeline, drug candidates are usually screened in vitro using two-dimensional or three-dimensional cell culture. However, these methods fail to accurately mimic the human disease state. This has led to the poor success rate of anticancer drugs in the preclinical stages since many drugs are abandoned due to inefficacy or toxicity when transitioned to whole-organism models. The common fruit fly, Drosophila melanogaster, has emerged as a beneficial system for modeling human cancers. Decades of fundamental research have shown the evolutionary conservation of key genes and signaling pathways between flies and humans. Moreover, Drosophila has a lower genetic redundancy in comparison to mammals. These factors, in addition to the advancement of genetic toolkits for manipulating gene expression, allow for the generation of complex Drosophila genotypes and phenotypes. Numerous studies have successfully created Drosophila models for colorectal, lung, thyroid, and brain cancers. These models were utilized in the high-throughput screening of FDA-approved drugs which led to the identification of several compounds capable of reducing proliferation and rescuing phenotypes. More noteworthy, Drosophila has also unlocked the potential for personalized therapies. Drosophila ‘avatars’ presenting the same mutations as a patient are used to screen multiple therapeutic agents targeting multiple pathways to find the most appropriate combination of drugs. The outcomes of these studies have translated to significant responses in patients with adenoid cystic carcinoma and metastatic colorectal cancers. Despite not being widely utilized, the concept of in vivo screening of drugs in Drosophila is making significant contributions to the current drug discovery pipeline. In this review, we discuss the application of Drosophila as a platform in anticancer drug discovery; with special focus on the cancer models that have been generated, drug libraries that have been screened and the status of personalized therapies. In addition, we elaborate on the biological and technical limitations of this system.

ModelMatcher: A scientist-centric online platform to facilitate collaborations between stakeholders of rare and undiagnosed disease research

Next-generation sequencing is a prevalent diagnostic tool for undiagnosed diseases and has played a significant role in rare disease gene discovery. Although this technology resolves some cases, others are given a list of possibly damaging genetic variants necessitating functional studies. Productive collaborations between scientists, clinicians, and patients (affected individuals) can help resolve such medical mysteries and provide insights into in vivo function of human genes. Furthermore, facilitating interactions between scientists and research funders, including nonprofit organizations or commercial entities, can dramatically reduce the time to translate discoveries from bench to bedside. Several systems designed to connect clinicians and researchers with a shared gene of interest have been successful. However, these platforms exclude some stakeholders based on their role or geography. Here we describe ModelMatcher, a global online matchmaking tool designed to facilitate cross-disciplinary collaborations, especially between scientists and other stakeholders of rare and undiagnosed disease research. ModelMatcher is integrated into the Rare Diseases Models and Mechanisms Network and Matchmaker Exchange, allowing users to identify potential collaborators in other registries. This living database decreases the time from when a scientist or clinician is making discoveries regarding their genes of interest, to when they identify collaborators and sponsors to facilitate translational and therapeutic research.

Embracing complexity in Drosophila cancer models

Cancer continues to be a leading cause of death worldwide, largely due to metastases and cachexia. It is a complex disease that is commonly associated with a variety of comorbidities. With global increases in ageing populations and obesity, multimorbidity is a rapidly growing clinical issue in the context of cancer. Cancer is also genetically heterogeneous, with a tumour's unique profile determining its incidence of metastasis, degree of cachexia and response to therapeutics. These complexities of human cancer are difficult to replicate in animal models and are, in part, responsible for the failures in translational cancer research. In this Perspective, we highlight the fruit fly, Drosophila melanogaster, as a powerful model organism to investigate multimorbidity and tumour diversity. We also highlight how harnessing these complexities in Drosophila can, potentially, enhance cancer research and advance therapeutic discoveries.

Mitochondria Dysfunction in Frontotemporal Dementia/Amyotrophic Lateral Sclerosis: Lessons From Drosophila Models

Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders characterized by declining motor and cognitive functions. Even though these diseases present with distinct sets of symptoms, FTD and ALS are two extremes of the same disease spectrum, as they show considerable overlap in genetic, clinical and neuropathological features. Among these overlapping features, mitochondrial dysfunction is associated with both FTD and ALS. Recent studies have shown that cells derived from patients' induced pluripotent stem cells (iPSC)s display mitochondrial abnormalities, and similar abnormalities have been observed in a number of animal disease models. Drosophila models have been widely used to study FTD and ALS because of their rapid generation time and extensive set of genetic tools. A wide array of fly models have been developed to elucidate the molecular mechanisms of toxicity for mutations associated with FTD/ALS. Fly models have been often instrumental in understanding the role of disease associated mutations in mitochondria biology. In this review, we discuss how mutations associated with FTD/ALS disrupt mitochondrial function, and we review how the use of Drosophila models has been pivotal to our current knowledge in this field.

Conditional CRISPR-Cas Genome Editing in Drosophila to Generate Intestinal Tumors

CRISPR-Cas has revolutionized genetics and extensive efforts have been made to enhance its editing efficiency by developing increasingly more elaborate tools. Here, we evaluate the CRISPR-Cas9 system in Drosophila melanogaster to assess its ability to induce stem cell-derived tumors in the intestine. We generated conditional tissue-specific CRISPR knockouts using different Cas9 expression vectors with guide RNAs targeting the BMP, Notch, and JNK pathways in intestinal progenitors such as stem cells (ISCs) and enteroblasts (EBs). Perturbing Notch and BMP signaling increased the proliferation of ISCs/EBs and resulted in the formation of intestinal tumors, albeit with different efficiencies. By assessing both the anterior and posterior regions of the midgut, we observed regional differences in ISC/EB proliferation and tumor formation upon mutagenesis. Surprisingly, high continuous expression of Cas9 in ISCs/EBs blocked age-dependent increase in ISCs/EBs proliferation and when combined with gRNAs targeting tumor suppressors, it prevented tumorigenesis. However, no such effects were seen when temporal parameters of Cas9 were adjusted to regulate its expression levels or with a genetically modified version, which expresses Cas9 at lower levels, suggesting that fine-tuning Cas9 expression is essential to avoid deleterious effects. Our findings suggest that modifications to Cas9 expression results in differences in editing efficiency and careful considerations are required when choosing reagents for CRISPR-Cas9 mutagenesis studies. In summary, Drosophila can serve as a powerful model for context-dependent CRISPR-Cas based perturbations and to test genome-editing systems in vivo.

Low-protein diet applied as part of combination therapy or stand-alone normalizes lifespan and tumor proliferation in a model of intestinal cancer

Tumors of the intestinal tract are among the most common tumor diseases in humans, but, like many other tumor entities, show an unsatisfactory prognosis with a need for effective therapies. To test whether nutritional interventions and a combination with a targeted therapy can effectively cure these cancers, we used the fruit fly Drosophila as a model. In this system, we induced tumors by EGFR overexpression in intestinal stem cells. Limiting the amount of protein in the diet restored life span to that of control animals. In combination with a specific EGFR inhibitor, all major tumor-associated phenotypes could be rescued. This form of treatment was also successful in a real treatment scenario, which means when they started after the full tumor phenotype was expressed. In conclusion, reduced protein administration can be a very promising form of adjuvant cancer therapy.

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.

Human Protein Complex-Based Drug Signatures for Personalized Cancer Medicine

Disease signature-based drug repositioning approaches typically first identify a disease signature from gene expression profiles of disease samples to represent a particular disease. Then such a disease signature is connected with the drug-induced gene expression profiles to find potential drugs for the particular disease. In order to obtain reliable disease signatures, the size of disease samples should be large enough, which is not always a single case in practice, especially for personalized medicine. On the other hand, the sample sizes of drug-induced gene expression profiles are generally large. In this study, we propose a new drug repositioning approach (HDgS), in which the drug signature is first identified from drug-induced gene expression profiles, and then connected to the gene expression profiles of disease samples to find the potential drugs for patients. In order to take the dependencies among genes into account, the human protein complexes (HPC) are used to define the drug signature. The proposed HDgS is applied to the drug-induced gene expression profiles in LINCS and several types of cancer samples. The results indicate that the HPC-based drug signature can effectively find drug candidates for patients and that the proposed HDgS can be applied for personalized medicine with even one patient sample.

Genetically altered animal models for ATP1A3-related disorders

Within the past 20 years, particularly with the advent of exome sequencing technologies, autosomal dominant and de novo mutations in the gene encoding the neurone-specific α3 subunit of the Na+,K+-ATPase (NKA α3) pump, ATP1A3, have been identified as the cause of a phenotypic continuum of rare neurological disorders. These allelic disorders of ATP1A3 include (in approximate order of severity/disability and onset in childhood development): polymicrogyria; alternating hemiplegia of childhood; cerebellar ataxia, areflexia, pes cavus, optic atrophy and sensorineural hearing loss syndrome; relapsing encephalopathy with cerebellar ataxia; and rapid-onset dystonia-parkinsonism. Some patients present intermediate, atypical or combined phenotypes. As these disorders are currently difficult to treat, there is an unmet need for more effective therapies. The molecular mechanisms through which mutations in ATP1A3 result in a broad range of neurological symptoms are poorly understood. However, in vivo comparative studies using genetically altered model organisms can provide insight into the biological consequences of the disease-causing mutations in NKA α3. Herein, we review the existing mouse, zebrafish, Drosophila and Caenorhabditis elegans models used to study ATP1A3-related disorders, and discuss their potential contribution towards the understanding of disease mechanisms and development of novel therapeutics.

Crowdsourced identification of multi-target kinase inhibitors for RET- and TAU- based disease: The Multi-Targeting Drug DREAM Challenge

A continuing challenge in modern medicine is the identification of safer and more efficacious drugs. Precision therapeutics, which have one molecular target, have been long promised to be safer and more effective than traditional therapies. This approach has proven to be challenging for multiple reasons including lack of efficacy, rapidly acquired drug resistance, and narrow patient eligibility criteria. An alternative approach is the development of drugs that address the overall disease network by targeting multiple biological targets ('polypharmacology'). Rational development of these molecules will require improved methods for predicting single chemical structures that target multiple drug targets. To address this need, we developed the Multi-Targeting Drug DREAM Challenge, in which we challenged participants to predict single chemical entities that target pro-targets but avoid anti-targets for two unrelated diseases: RET-based tumors and a common form of inherited Tauopathy. Here, we report the results of this DREAM Challenge and the development of two neural network-based machine learning approaches that were applied to the challenge of rational polypharmacology. Together, these platforms provide a potentially useful first step towards developing lead therapeutic compounds that address disease complexity through rational polypharmacology.

A Personalized Therapeutics Approach Using an In Silico Drosophila Patient Model Reveals Optimal Chemo- and Targeted Therapy Combinations for Colorectal Cancer

In silico models of biomolecular regulation in cancer, annotated with patient-specific gene expression data, can aid in the development of novel personalized cancer therapeutic strategies. Drosophila melanogaster is a well-established animal model that is increasingly being employed to evaluate such preclinical personalized cancer therapies. Here, we report five Boolean network models of biomolecular regulation in cells lining the Drosophila midgut epithelium and annotate them with colorectal cancer patient-specific mutation data to develop an in silico Drosophila Patient Model (DPM). We employed cell-type-specific RNA-seq gene expression data from the FlyGut-seq database to annotate and then validate these networks. Next, we developed three literature-based colorectal cancer case studies to evaluate cell fate outcomes from the model. Results obtained from analyses of the proposed DPM help: (i) elucidate cell fate evolution in colorectal tumorigenesis, (ii) validate cytotoxicity of nine FDA-approved CRC drugs, and (iii) devise optimal personalized treatment combinations. The personalized network models helped identify synergistic combinations of paclitaxel-regorafenib, paclitaxel-bortezomib, docetaxel-bortezomib, and paclitaxel-imatinib for treating different colorectal cancer patients. Follow-on therapeutic screening of six colorectal cancer patients from cBioPortal using this drug combination demonstrated a 100% increase in apoptosis and a 100% decrease in proliferation. In conclusion, this work outlines a novel roadmap for decoding colorectal tumorigenesis along with the development of personalized combinatorial therapeutics for preclinical translational studies.

A platform utilizing Drosophila ovulation for nonhormonal contraceptive screening

A significant unmet need for new contraceptive options for both women and men remains due to side-effect profiles, medical concerns, and the inconvenience of many currently available contraceptive products. Unfortunately, the development of novel nonsteroidal female contraceptive medicine has been stalled in the last couple of decades due to the lack of effective screening platforms. Drosophila utilizes conserved signaling pathways for follicle rupture, a final step in ovulation that is essential for female reproduction. Therefore, we explored the potential to use Drosophila as a model to screen compounds that could inhibit follicle rupture and be nonsteroidal contraceptive candidates. Using our ex vivo follicle rupture assay, we screened 1,172 Food and Drug Administration (FDA)-approved drugs and identified six drugs that could inhibit Drosophila follicle rupture in a dose-dependent manner. In addition, we characterized the molecular actions of these drugs in the inhibition of adrenergic signaling and follicle rupture. Furthermore, we validated that three of the four drugs consistently inhibited mouse follicle rupture in vitro and that two of them did not affect progesterone production. Finally, we showed that chlorpromazine, one of the candidate drugs, can significantly inhibit mouse follicle rupture in vivo. Our work suggests that Drosophila ovulation is a valuable platform for identifying lead compounds for nonsteroidal contraceptive development and highlights the potential of these FDA-approved drugs as novel nonsteroidal contraceptive agents.

Future Match Making: When Pediatric Oncology Meets Organoid Technology

Unlike adult cancers that frequently result from the accumulation in time of mutational “hits” often linked to lifestyle, childhood cancers are emerging as diseases of dysregulated development through massive epigenetic alterations. The ability to reconstruct these differences in cancer models is therefore crucial for better understanding the uniqueness of pediatric cancer biology. Cancer organoids (i.e., tumoroids) represent a promising approach for creating patient-derived in vitro cancer models that closely recapitulate the overall pathophysiological features of natural tumorigenesis, including intra-tumoral heterogeneity and plasticity. Though largely applied to adult cancers, this technology is scarcely used for childhood cancers, with a notable delay in technological transfer. However, tumoroids could provide an unprecedented tool to unravel the biology of pediatric cancers and improve their therapeutic management. We herein present the current state-of-the-art of a long awaited and much needed matchmaking.

Status quo and future prospects of artificial neural network from the perspective of gastroenterologists

Artificial neural networks (ANNs) are one of the primary types of artificial intelligence and have been rapidly developed and used in many fields. In recent years, there has been a sharp increase in research concerning ANNs in gastrointestinal (GI) diseases. This state-of-the-art technique exhibits excellent performance in diagnosis, prognostic prediction, and treatment. Competitions between ANNs and GI experts suggest that efficiency and accuracy might be compatible in virtue of technique advancements. However, the shortcomings of ANNs are not negligible and may induce alterations in many aspects of medical practice. In this review, we introduce basic knowledge about ANNs and summarize the current achievements of ANNs in GI diseases from the perspective of gastroenterologists. Existing limitations and future directions are also proposed to optimize ANN’s clinical potential. In consideration of barriers to interdisciplinary knowledge, sophisticated concepts are discussed using plain words and metaphors to make this review more easily understood by medical practitioners and the general public.

Sensitive High-Throughput Assays for Tumour Burden Reveal the Response of a Drosophila melanogaster Model of Colorectal Cancer to Standard Chemotherapies

Drosophila melanogaster (Drosophila) models of cancer are emerging as powerful tools to investigate the basic mechanisms underlying tumour progression and identify novel therapeutics. Rapid and inexpensive, it is possible to carry out genetic and drug screens at a far larger scale than in vertebrate organisms. Such whole-organism-based drug screens permits assessment of drug absorption and toxicity, reducing the possibility of false positives. Activating mutations in the Wnt and Ras signalling pathways are common in many epithelial cancers, and when driven in the adult Drosophila midgut, it induces aggressive intestinal tumour-like outgrowths that recapitulate many aspects of human colorectal cancer (CRC). Here we have taken a Drosophila CRC model in which tumourous cells are marked with both GFP and luciferase reporter genes, and developed novel high-throughput assays for quantifying tumour burden. Leveraging these assays, we find that the Drosophila CRC model responds rapidly to treatment with standard CRC-drugs, opening the door to future rapid genetic and drug screens.

Model organisms contribute to diagnosis and discovery in the undiagnosed diseases network: current state and a future vision

Decreased sequencing costs have led to an explosion of genetic and genomic data. These data have revealed thousands of candidate human disease variants. Establishing which variants cause phenotypes and diseases, however, has remained challenging. Significant progress has been made, including advances by the National Institutes of Health (NIH)-funded Undiagnosed Diseases Network (UDN). However, 6000-13,000 additional disease genes remain to be identified. The continued discovery of rare diseases and their genetic underpinnings provides benefits to affected patients, of whom there are more than 400 million worldwide, and also advances understanding the mechanisms of more common diseases. Platforms employing model organisms enable discovery of novel gene-disease relationships, help establish variant pathogenicity, and often lead to the exploration of underlying mechanisms of pathophysiology that suggest new therapies. The Model Organism Screening Center (MOSC) of the UDN is a unique resource dedicated to utilizing informatics and functional studies in model organisms, including worm (Caenorhabditis elegans), fly (Drosophila melanogaster), and zebrafish (Danio rerio), to aid in diagnosis. The MOSC has directly contributed to the diagnosis of challenging cases, including multiple patients with complex, multi-organ phenotypes. In addition, the MOSC provides a framework for how basic scientists and clinicians can collaborate to drive diagnoses. Customized experimental plans take into account patient presentations, specific genes and variant(s), and appropriateness of each model organism for analysis. The MOSC also generates bioinformatic and experimental tools and reagents for the wider scientific community. Two elements of the MOSC that have been instrumental in its success are (1) multidisciplinary teams with expertise in variant bioinformatics and in human and model organism genetics, and (2) mechanisms for ongoing communication with clinical teams. Here we provide a position statement regarding the central role of model organisms for continued discovery of disease genes, and we advocate for the continuation and expansion of MOSC-type research entities as a Model Organisms Network (MON) to be funded through grant applications submitted to the NIH, family groups focused on specific rare diseases, other philanthropic organizations, industry partnerships, and other sources of support.

Modeling Neoplastic Growth in Renal Cell Carcinoma and Polycystic Kidney Disease

Renal cell carcinoma (RCC) and autosomal dominant polycystic kidney disease (ADPKD) share several characteristics, including neoplastic cell growth, kidney cysts, and limited therapeutics. As well, both exhibit impaired vasculature and compensatory VEGF activation of angiogenesis. The PI3K/AKT/mTOR and Ras/Raf/ERK pathways play important roles in regulating cystic and tumor cell proliferation and growth. Both RCC and ADPKD result in hypoxia, where HIF-α signaling is activated in response to oxygen deprivation. Primary cilia and altered cell metabolism may play a role in disease progression. Non-coding RNAs may regulate RCC carcinogenesis and ADPKD through their varied effects. Drosophila exhibits remarkable conservation of the pathways involved in RCC and ADPKD. Here, we review the progress towards understanding disease mechanisms, partially overlapping cellular and molecular dysfunctions in RCC and ADPKD and reflect on the potential for the agile Drosophila genetic model to accelerate discovery science, address unresolved mechanistic aspects of these diseases, and perform rapid pharmacological screens.

Mouse avatars of human cancers: the temporality of translation in precision oncology

Patient-derived xenografts (PDXs) are currently promoted as new translational models in precision oncology. PDXs are immunodeficient mice with human tumors that are used as surrogate models to represent specific types of cancer. By accounting for the genetic heterogeneity of cancer tumors, PDXs are hoped to provide more clinically relevant results in preclinical research. Further, in the function of so-called "mouse avatars", PDXs are hoped to allow for patient-specific drug testing in real-time (in parallel to treatment of the corresponding cancer patient). This paper examines the circulation of knowledge and bodily material across the species boundary of human and personalized mouse model, historically as well as in contemporary practices. PDXs raise interesting questions about the relation between animal model and human patient, and about the capacity of hybrid or interspecies models to close existing translational gaps. We highlight that the translational potential of PDXs not only depends on representational matching of model and target, but also on temporal alignment between model development and practical uses. Aside from the importance of ensuring temporal stability of human tumors in a murine body, the mouse avatar concept rests on the possibility of aligning the temporal horizons of the clinic and the lab. We examine strategies to address temporal challenges, including cryopreservation and biobanking, as well as attempts to speed up translation through modification and use of faster developing organisms. We discuss how featured model virtues change with precision oncology, and contend that temporality is a model feature that deserves more philosophical attention.

A Drosophila platform identifies a novel, personalized therapy for a patient with adenoid cystic carcinoma

Adenoid cystic carcinoma (ACC) is a rare cancer type that originates in the salivary glands. Tumors commonly invade along nerve tracks in the head and neck, making surgery challenging. Follow-up treatments for recurrence or metastasis including chemotherapy and targeted therapies have shown limited efficacy, emphasizing the need for new therapies. Here, we report a Drosophila-based therapeutic approach for a patient with advanced ACC disease. A patient-specific Drosophila transgenic line was developed to model the five major variants associated with the patient's disease. Robotics-based screening identified a three-drug cocktail—vorinostat, pindolol, tofacitinib—that rescued transgene-mediated lethality in the Drosophila patient-specific line. Patient treatment led to a sustained stabilization and a partial metabolic response of 12 months. Subsequent resistance was associated with new genomic amplifications and deletions. Given the lack of options for patients with ACC, our data suggest that this approach may prove useful for identifying novel therapeutic candidates.

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Personalized therapy was developed for patient with Adenoid Cystic Carcinoma

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Genomics analysis was leveraged to establish a Drosophila ‘personalized patient avatar’

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A robotics-based screen identified a novel three drug therapeutic cocktail

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12 months response was followed by relapse and significant tumor genomic re-wiring

Cross-species identification of PIP5K1-, splicing- and ubiquitin-related pathways as potential targets for RB1-deficient cells

The RB1 tumor suppressor is recurrently mutated in a variety of cancers including retinoblastomas, small cell lung cancers, triple-negative breast cancers, prostate cancers, and osteosarcomas. Finding new synthetic lethal (SL) interactions with RB1 could lead to new approaches to treating cancers with inactivated RB1. We identified 95 SL partners of RB1 based on a Drosophila screen for genetic modifiers of the eye phenotype caused by defects in the RB1 ortholog, Rbf1. We validated 38 mammalian orthologs of Rbf1 modifiers as RB1 SL partners in human cancer cell lines with defective RB1 alleles. We further show that for many of the RB1 SL genes validated in human cancer cell lines, low activity of the SL gene in human tumors, when concurrent with low levels of RB1 was associated with improved patient survival. We investigated higher order combinatorial gene interactions by creating a novel Drosophila cancer model with co-occurring Rbf1, Pten and Ras mutations, and found that targeting RB1 SL genes in this background suppressed the dramatic tumor growth and rescued fly survival whilst having minimal effects on wild-type cells. Finally, we found that drugs targeting the identified RB1 interacting genes/pathways, such as UNC3230, PYR-41, TAK-243, isoginkgetin, madrasin, and celastrol also elicit SL in human cancer cell lines. In summary, we identified several high confidence, evolutionarily conserved, novel targets for RB1-deficient cells that may be further adapted for the treatment of human cancer.

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.

The level of oncogenic Ras determines the malignant transformation of Lkb1 mutant tissue in vivo

The genetic and metabolic heterogeneity of RAS-driven cancers has confounded therapeutic strategies in the clinic. To address this, rapid and genetically tractable animal models are needed that recapitulate the heterogeneity of RAS-driven cancers in vivo. Here, we generate a Drosophila melanogaster model of Ras/Lkb1 mutant carcinoma. We show that low-level expression of oncogenic Ras (RasLow) promotes the survival of Lkb1 mutant tissue, but results in autonomous cell cycle arrest and non-autonomous overgrowth of wild-type tissue. In contrast, high-level expression of oncogenic Ras (RasHigh) transforms Lkb1 mutant tissue resulting in lethal malignant tumors. Using simultaneous multiview light-sheet microcopy, we have characterized invasion phenotypes of Ras/Lkb1 tumors in living larvae. Our molecular analysis reveals sustained activation of the AMPK pathway in malignant Ras/Lkb1 tumors, and demonstrate the genetic and pharmacologic dependence of these tumors on CaMK-activated Ampk. We further show that LKB1 mutant human lung adenocarcinoma patients with high levels of oncogenic KRAS exhibit worse overall survival and increased AMPK activation. Our results suggest that high levels of oncogenic KRAS is a driving event in the malignant transformation of LKB1 mutant tissue, and uncovers a vulnerability that may be used to target this aggressive genetic subset of RAS-driven tumors.

Modeling neurodegeneration in Caenorhabditis elegans

The global burden of neurodegenerative diseases underscores the urgent need for innovative strategies to define new drug targets and disease-modifying factors. The nematode Caenorhabditis elegans has served as the experimental subject for multiple transformative discoveries that have redefined our understanding of biology for ∼60 years. More recently, the considerable attributes of C. elegans have been applied to neurodegenerative diseases, including amyotrophic lateral sclerosis, Alzheimer's disease, Parkinson's disease and Huntington's disease. Transgenic nematodes with genes encoding normal and disease variants of proteins at the single- or multi-copy level under neuronal-specific promoters limits expression to select neuronal subtypes. The anatomical transparency of C. elegans affords the use of co-expressed fluorescent proteins to follow the progression of neurodegeneration as the animals age. Significantly, a completely defined connectome facilitates detailed understanding of the impact of neurodegeneration on organismal health and offers a unique capacity to accurately link cell death with behavioral dysfunction or phenotypic variation in vivo. Moreover, chemical treatments, as well as forward and reverse genetic screening, hasten the identification of modifiers that alter neurodegeneration. When combined, these chemical-genetic analyses establish critical threshold states to enhance or reduce cellular stress for dissecting associated pathways. Furthermore, C. elegans can rapidly reveal whether lifespan or healthspan factor into neurodegenerative processes. Here, we outline the methodologies employed to investigate neurodegeneration in C. elegans and highlight numerous studies that exemplify its utility as a pre-clinical intermediary to expedite and inform mammalian translational research.

Summary: While unsurpassed as an experimental system for fundamental biology, Caenorhabditis elegans remains undervalued for its translational potential. Here, we highlight significant outcomes from, and resources available for, C. elegans-based research into neurodegenerative disorders.

The Leukemic Fly: Promises and Challenges

Leukemia involves different types of blood cancers, which lead to significant mortality and morbidity. Murine models of leukemia have been instrumental in understanding the biology of the disease and identifying therapeutics. However, such models are time consuming and expensive in high throughput genetic and drug screening. Drosophilamelanogaster has emerged as an invaluable in vivo model for studying different diseases, including cancer. Fruit flies possess several hematopoietic processes and compartments that are in close resemblance to their mammalian counterparts. A number of studies succeeded in characterizing the fly's response upon the expression of human leukemogenic proteins in hematopoietic and non-hematopoietic tissues. Moreover, some of these studies showed that these models are amenable to genetic screening. However, none were reported to be tested for drug screening. In this review, we describe the Drosophila hematopoietic system, briefly focusing on leukemic diseases in which fruit flies have been used. We discuss myeloid and lymphoid leukemia fruit fly models and we further highlight their roles for future therapeutic screening. In conclusion, fruit fly leukemia models constitute an interesting area which could speed up the process of integrating new therapeutics when complemented with mammalian models.

Rounding up the Usual Suspects: Assessing Yorkie, AP-1, and Stat Coactivation in Tumorigenesis

Can hyperactivation of a few key signaling effectors be the underlying reason for the majority of epithelial cancers despite different driver mutations? Here, to address this question, we use the Drosophila model, which allows analysis of gene expression from tumors with known initiating mutations. Furthermore, its simplified signaling pathways have numerous well characterized targets we can use as pathway readouts. In Drosophila tumor models, changes in the activities of three pathways, Jun N-terminal Kinase (JNK), Janus Kinase / Signal Transducer and Activator of Transcription (JAK/STAT), and Hippo, mediated by AP-1 factors, Stat92E, and Yorkie, are reported frequently. We hypothesized this may indicate that these three pathways are commonly deregulated in tumors. To assess this, we mined the available transcriptomic data and evaluated the activity levels of eight pathways in various tumor models. Indeed, at least two out of our three suspects contribute to tumor development in all Drosophila cancer models assessed, despite different initiating mutations or tissues of origin. Surprisingly, we found that Notch signaling is also globally activated in all models examined. We propose that these four pathways, JNK, JAK/STAT, Hippo, and Notch, are paid special attention and assayed for systematically in existing and newly developed models.

Bibliometric analysis of personalized humanized mouse and Drosophila models for effective combinational therapy in cancer patients

Research performed using model organisms such as mice and the fruit fly, Drosophila melanogaster has significantly enhanced our knowledge about cancer biology and the fundamental processes of cancer. This is because the major biological properties and genes associated with cancer including signaling pathways, oncogenes, tumor suppressors, and other regulators of cell growth and proliferation are evolutionary conserved. This review provides bibliometric analysis of research productivity, and performance of authors, institutions, countries, and journals associated with personalized animal cancer models, focussing on the role of Drosophila in cancer research, thus highlighting emerging trends in the field. A total of 1469 and 2672 original articles and reviews for Drosophila cancer model and patient-derived xenograft (PDX) respectively, were retrieved from the Scopus database and the most cited papers were thoroughly analyzed. Our analysis indicates a steadily increasing productivity of the animal models and especially of mouse models in cancer research. In addition to the many different systems that address almost all aspects of tumor research in humanized animal models, a trend towards using tailored screening platforms with Drosophila models in particular will become widespread in the future. Having Drosophila models that recapitulate major genetic aspects of a given tumor will enable the development and validation of novel therapeutic strategies for specific cancers, and provide a platform for screening small molecule inhibitors and other anti-tumor compounds. The combination of Drosophila cancer models and mouse PDX models particularly is highly promising and should be one of the major research strategies the future.

Drug discovery and chemical probing in Drosophila

Flies are increasingly utilized in drug discovery and chemical probing in vivo, which are novel technologies complementary to genetic probing in fundamental biological studies. Excellent genetic conservation, small size, short generation time, and over one hundred years of genetics make Drosophila an attractive model for rapid assay readout and use of analytical amounts of compound, enabling the experimental iterations needed in early drug development at a fraction of time and costs. Here, we describe an effective drug-testing pipeline using adult flies that can be easily implemented to study several disease models and different genotypes to discover novel molecular insight, probes, quality lead compounds, and develop novel prototype drugs.