Mouliganesh , Vaibhav Tiwary , V. Ramya Priya , N. Yamini Sree , H. Vinu Annapoorna , Diganta K. Saikia , Kaustav Mahanta , Kavitha Thirumurugan. Ellagic acid prolongs the lifespan of Drosophila melanogaster. GeroScience , 42 1 , Drosophila melanogaster in nutrition research—the importance of standardizing experimental diets. Nutrigenomics as a tool to study the impact of diet on aging and age-related diseases: the Drosophila approach.
Drosophila melanogaster as an alternative model organism in nutrigenomics. Marine Drugs , 17 11 , Bayliak , Olexandra B. Abrat , Janet M. Storey , Kenneth B. Storey , Volodymyr I. Interplay between diet-induced obesity and oxidative stress: Comparison between Drosophila and mammals. Ipharraguerre , Anika E. Pair your accounts. Your Mendeley pairing has expired. Please reconnect. This website uses cookies to improve your user experience. By continuing to use the site, you are accepting our use of cookies.
Investors Careers. Life Science Cameras. Control Software. Physical Science Cameras. OEM Portfolio. Support Service and Support. Learning Centre Asset. Becher, John E. Pool, and Marcus C. Franz, W. Wood, and P. Tomer, K. Khairy, F. Amat and P. Second, we describe classic and novel Drosophila models used to study different cancers, with the objective to discuss their strengths and limitations on their use to identify signals driving growth cell autonomously and within organs, drug discovery and for therapeutic approaches.
The fruit fly, Drosophila melanogaster , is used as a model organism to study disciplines ranging from fundamental genetics to the development of tissues and organs. These features, together with a brief generation time, low maintenance costs, and the availability of powerful genetic tools, allow the fruit fly to be eligible to study complex pathways relevant in biomedical research, including cancer. Indeed, publications that use flies to model cancer have exponentially increased in the last 10 years, as shown in the graph of Figure 1 , suggesting the relevance of this model to cancer research.
Figure 1. In this review we first describe the basic biological mechanisms responsible for uncontrolled growth conserved between humans and flies.
We placed a particular emphasis on the characterization of epithelial tumors from most studied models gut and brain , to novel approaches for studying tumor-induced angiogenesis, prostate, thyroid and lung cancers, with the goal to discuss their strengths and limitations. In the second part, we analyze few physiological mechanisms that uncover potential non-autonomous mechanisms controlling growth, including the relation between the immune cells macrophages and the growth of epithelial cells, or the function of lipid metabolism in cancer growth.
Finally, we discuss how Drosophila models are used to find novel interesting therapeutic approaches. Cancer cells are characterized by unrestrained proliferation that results from defects in signaling driving cellular growth, apoptosis and changes in metabolic pathways. At cellular level, the hyperproliferative status of cancer cells is mainly due to the activation of growth signals induced by proto-oncogenes e.
Tumor cells escape the anti-proliferative effect of tumor suppressor genes, such as RB retinoblastoma-associated and TP53 genes Duronio and Xiong, , through mutations in these genes, which result in uncontrolled growth Hanahan and Weinberg, , ; Hariharan and Bilder, Apoptotic cell death represents another physiological mechanism to maintain cellular homeostasis, and cancer cells have developed strategies to evade apoptosis, i.
Cancer cells also exhibit alterations in metabolic pathways that contribute to their survival. Rapidly proliferating cells have a high metabolic rate and suffer from low oxygen conditions hypoxia. Cancers cells also exhibit a metabolic switch where they reprogram their metabolism to use an alternative and less abundant anabolic pathway to sustain their growth.
This metabolic switch is not yet completely characterized but is supported by the activation of oncogenes, including Myc that also activates glutaminolysis to fuel the TCA cycle with anaplerotic reactions to produce the intermediates necessary for cellular biosynthesis Hsieh and Dang, The last stage of tumorigenesis is represented by the invasive and metastatic capabilities of tumor cells to disrupt the apical-basal cell polarity, a process that is associated with the downregulation of cell-cell contact molecules and the release of metalloproteases MMP1 , lytic enzymes that degrade the extracellular matrix ECM allowing tumor cells to escape and colonize an environment that suites them and to acquire new oncogenic properties Massague and Obenauf, ; Lambert et al.
A variety of studies are now focused on how the tumor micro environment TME , a specific niche composed of fibroblasts, lymphocytes and immune cells, that may shape pre-cancer cells for their progression into cancer cells and it may select the development of metastasis Massague and Obenauf, Most of the signaling pathways controlling cell growth and invasion in mammals have a conserved function in flies allowing their modulation into models that mimic tumor's biology in a simple model organism like Drosophila Millburn et al.
The combination of genetic screens with the availability of powerful recombination techniques enabled also a rapid characterization of the primary function of conserved oncogenes and of tumor suppressor genes in a whole animal Sonoshita and Cagan, In addition, recent studies using Drosophila imaginal discs explored the mechanisms that govern growth in epithelial tumors and their interaction with the local TME and stromal cells, including some steps in the recruitment of the immune cells macrophages to the tumor mass Herranz et al.
Epithelial tissues are characterized by a specific cell architecture composed of junctions and apical and baso-lateral membrane domains that are crucial for the maintenance of cell-physiological functions. Loss of cell adhesion and cell polarity, with an increase of cell motility, are indeed characteristic early cancer traits. In this context, Drosophila larval imaginal discs are a monolayer epithelium that is limited apically by a squamous epithelium peripodial membrane and, basally to the notum, by a layer of myoblasts embedded in Extracellular Matrix, and constitute a perfect system in which to model the onset of epithelial cancer progression.
These larval organs are indeed morphologically and biochemically comparable to mammalian epithelia Wodarz and Nathke, Moreover, the prominent signaling pathways that regulate growth in humans are conserved in the fruit fly Figure 2 , allowing the use of this animal model to examine the hallmarks of cancer St. Johnston, During the last few years, the imaginal wing and eye discs have been used successfully to study tumor growth and invasion, to investigate the function of cancer genes, and to perform chemical screenings Tipping and Perrimon, The imaginal discs also represent an excellent model to analyze oncogenic cooperation: thanks to the use of the MARCM system Lee and Luo, , it is feasible to induce simultaneously in single cells mutations in tumor suppressor genes e.
Figure 2. Major pathways converging on uncontrolled growth in Drosophila epithelial cells. The signaling pathways outlined confer growth, migration and invasive capabilities to epithelial cells both in vertebrates and flies. Models that mimic the growth of epithelial cancer cells and their ability to undergo metastasis in Drosophila have been established by inducing the cooperation between oncogenes RED like the active form of Ras Ras V 12 together with the loss of function of cell polarity genes GREEN Brumby and Richardson, ; Pagliarini and Xu, Activation of the JNK signaling, with the concomitant loss of cell polarity, induces metalloproteases MMP-1 and confers to the epithelial cells the distinct characteristics of migration and invasion, hallmarks of tumor growth Uhlirova et al.
Cellular junctions and a proper apical-basal cell polarity are fundamental for the maintenance of epithelial tissue architecture and function. During early cancer stages, tissues lose these properties and cells subvert their normal growth rate and acquire invasive and migratory behaviors Wodarz and Nathke, ; Bryant and Mostov, Alterations in these proteins provoke continued cell proliferation, loss of differentiation and complete loss of tissue architecture, resulting in neoplastic overgrowth Bilder, ; Grzeschik et al.
In addition, lgl mutant tissues, and tissues bearing dlg or scrib mutation, have the ability to form secondary tumors in the thorax, brain, wings, muscles, intestine and ovaries Woodhouse et al.
The loss of cell polarity impacts cell proliferation through the deregulation of the Hippo Hpo pathway, a signaling cascade involved in organ size maintenance Lu et al.
It is not yet fully known how lgl activity interacts with the Hpo cascade, but it was observed that its downregulation up-regulates cell cycle genes such as Cyclin E and E2F1 Grzeschik et al. HUGL-1 loss of function has been associated with a series of human malignancies Schimanski et al.
Finally, while the human genome encodes for only one homolog of the tumor suppressor scrib , a number of homologs are known for dlg which have been implicated in different types of cancer Halaoui and McCaffrey, Phosphorylated Yki is sequestered and degraded in the cytoplasm, resulting in the inhibition of its nuclear transcriptional activity and oncogenic function Harvey et al.
Upstream, the Hippo cascade is regulated by components of cell junctions, including cell adhesion molecules such as Merlin, a homolog of the human Neurofibromatosis Type 2 NF2 Genevet et al. This articulated system is also tightly regulated by other signaling pathways: for example, in the Drosophila imaginal wing disc, Lgl or aPKC deregulation results in JNK activation to promote Yki nuclear translocation via phosphorylation of Ajuba Jub , an upstream regulator of the cascade that binds to and inhibits Wts kinase activity Sun and Irvine, In addition to the regulation of cell-cell interaction signals, components of the Hippo pathway have been found to be sensitive to mechanical stress Panciera et al.
This mechanotransduction function is critical in the control of physiological pathways, and its deregulation may contribute to the abnormal cell behavior in diseases such as cancer, where the cells in the tumor have to sustain physical forces generated by tissue overgrowth. One possible explanation for this different behavior may be that the N-terminus of Yki is missing a domain necessary to bind PDZ-containing proteins, which is found in its human counterpart YAP, and is necessary for the activation of the integrin-Src adhesion branch of the pathway Elbediwy and Thompson, These ligands bind to receptor tyrosine kinases RTKs to activate downstream signaling, in particular its core complex, which is represented by the guanidine exchange factor Son of Sevenless SOS that, in turn, activates the small G proteins RAS on the cell membrane.
A second transcriptional repressor is Capicua Cic , an HMG box-containing protein highly conserved in vertebrates Simon-Carrasco et al.
Interestingly, in the last couple of years, this protein was found to possess oncogenic properties and be overexpressed in many tumors Simon-Carrasco et al. Even though MAPK targets in Drosophila are less abundant than in mammals, its activation and translocation to the nucleus results in a growth phenotype mimicking a few characteristic steps of growth in tumor cells Brumby et al.
Activation of Ras is considered a cancer distinctive trait both in Drosophila and humans, and it represents one of the strategies to model human cancer in flies. In the epithelial cells of the wing imaginal disc, Ras1 activation triggers hyperproliferation but also determines cell fate Prober and Edgar, Ras activation is at the crossroads of other growth factor signaling cascades: recently, a link to Hpo function was shown in Drosophila epithelial cells, where Ras activation was able to induce the tissues to switch from a pro-differentiative to a pro-growth program by modulating SWH's transcriptional output Pascual et al.
Ras increases cell proliferation also through the transcriptional regulation of growth factors and their receptors. Because of all these functional homologies to human RAS, its activation in Drosophila is considered a good method to establish models that mimic tumor growth.
Its function is variable and depends also on the cellular environment: it can indeed induce cell proliferation and migration, but its major role is to induce apoptosis Igaki, Cell death is induced by the expression of the pro-apoptotic genes hid, reaper and grim , whose activity inhibits the pro-survival protein dIAP1 Weston and Davis, In Drosophila cancer cells, the JNK pathway plays a dual role, by suppressing or promoting growth depending on the context Brumby and Richardson, ; Uhlirova et al.
On the contrary, in tumor cells with active RAS, apoptosis is blocked and JNK signaling acts as a tumor promoter transcribing genes involved in growth and invasion such as MMP1 Igaki et al. The overexpression of activated RAS together with Hep ras v 12 hep wt gives cells invasive and metastatic abilities, highlighting how these pathways converge to induce transformation in epithelia.
Activation of TORC1 results in phosphorylation of ribosomal protein kinase pS6 S6K and of eukaryotic translation initiation factor 4E-binding protein-1 4E-BP1 , thereby triggering protein synthesis and initiation of translation. Insulin and TOR activities are also balanced by a negative feedback mechanism that is activated when S6K is hyper-activated to counteract insulin activity.
This feedback mechanism is reduced in pathological conditions, such as the Tuberous Sclerosis Complex syndrome TSC , where cells carrying tsc1 or tsc2 mutations display an abnormal increase in size and exhibit constitutive phosphorylation of S6K Saxton and Sabatini, As members of PI3Ks and TOR signaling are frequently activated in human tumors, they are attractive targets for cancer treatment.
MYC is one of the most studied oncogenes, and its misexpression is associated with various tumor types including meningioma, Burkitt's lymphoma, medulloblastoma and hepatocellular carcinoma Hsieh and Dang, Drosophila Myc is the sole fly member of the family of transcription factors that in mammals is composed of three genes N-, L-, and c-MYC Gallant et al.
Notably, ubiquitous expression of myc increases cell mass resulting in enrichment of genes encoding components of the nucleolus and of the ribosome; this evidence, concomitantly with Myc's ability to indirectly stimulate RNA pol I and III Grewal et al. Myc activity is finely regulated, and while its expression is required at physiological levels during development, an excess of its activity triggers autonomous cell death and unbalanced growth Grifoni and Bellosta, Myc regulation of the cellular metabolic milieu is highly similar in Drosophila to the regulation found in tumor cells DeBerardinis et al.
Fascinatingly, these evolutionary functions of Myc to control mass and metabolism, resulted in the selective advantage of growth of epithelial cells described as cell competition and characterized in the monolayer epithelia composing Drosophila's imaginal discs Johnston, Briefly, cells expressing Myc create a competitive environment and they grow at the expense of wild-type cells that are killed by non cell-autonomous apoptosis de la Cova et al.
Myc-induced cell competition was also shown to be necessary in vertebrates to eliminate unfit cells losers during early embryogenesis Claveria and Torres, More recently, evidence that sustains a central role for Myc-induced cell competition in the early steps of tumor formation have shown Myc present at high levels in cells surrounding the tumor near dying cells, potentially allowing the winner cells to expand and to eliminate the surrounding wild-type cells, thus establishing the first evidence of Myc involved in a tumor growth competitive environment Johnston, ; Di Giacomo et al.
Another form of cell competition is regulated by cell polarity genes lgl, scrib, dlg and by endocytic genes such as Rab5. Cells mutant for these genes behave as losers and were eliminated by wild-type cells Brumby and Richardson, ; Menendez et al. Similar to mammalian counterparts, the Drosophila adult gut is specialized in the digestion of food, the absorption of nutrients, and for controlling the defense response against infection Tian et al.
Based on these distinct functions, the Drosophila gut is composed of three parts: foregut, midgut, and hindgut. Among them, the midgut has a distinct architecture that resembles the digestive tract of vertebrates. The epithelium is a monolayer that is replenished by Intestinal Stem Cells ISCs that differentiate to either enteroblasts EB or pre-enteroendocrine cells pre-EE , that then differentiate into absorptive enterocytes EC or secretory enteroendocrine cells EE.
Thanks to significant similarities in the physiology between the Drosophila gut and the intestine of vertebrates Apidianakis and Rahme, , Drosophila adult midgut epithelium has been used to study the contribution of signaling pathways i. In vertebrates, the majority of sporadic cases of colorectal cancer and familial adenomatous polyposis FAP cancer syndrome are associated with activation of Wnt signaling Bienz and Clevers, In humans, abnormal expression of Wnt in ISCs promotes adenoma formation, while deletions in mouse ISCs of the tumor suppressor adenomatous polyposis coli gene APC triggers the initial step of colon-adenoma formation Barker et al.
In Drosophila , loss of the Apc gene, leads to the over proliferation of ISCs in the gut, resulting in loss of epithelial cell polarity, hyperplasia and epithelial overgrowth resembling that of intestinal adenomas induced by the loss of APC Yu et al. Another aggressive oncogene that is hyper-activated upon Apc loss, in mouse and human intestinal adenomas is the non-receptor tyrosine kinase c-Src Yeatman, Notably, these results recapitulate an important part of the function of mammalian c-Src in the progenitor cells of the intestine during homeostasis and adenoma formation, suggesting a conserved role of this gene in flies in controlling proper ISCs proliferation.
Recently, Drosophila was also used to generate multigenic models of colon cancer using data from patients from The Cancer Genome Atlas.
Interestingly, the outcomes of these models mimicked important properties of human cancers, and can be explored and used in chemical screens to find new combinations of cancer-relevant drugs Bangi et al.
Studies, using Drosophila models, to characterize intestinal human pathophysiology, revealed the high conservation between these species of the mechanisms underlaying colorectal tumorigenesis Christofi and Apidianakis, , and further revealed also the mechanisms that control the processes leading to bacterial-mediated inflammation Lemaitre and Hoffmann, Meningioma are the most common intracranial tumors Claus et al.
Increased risk of meningiomas was associated also with neurofibromatosis type II syndrome, where mutations within the tumor suppressor gene Suppressor of fused SUFU was associated with hereditary meningiomas Aavikko et al. In GBM, Notch activity is associated with the control of Glioma Stem Cell GSC , since its activity regulates asymmetric cell division and Notch unbalanced expression leads to uncontrolled growth and high malignancy Mukherjee et al. Because of its conserved function, Notch pathway is now an important target for therapeutic intervention in brain cancer treatment Yuan et al.
The current understanding of asymmetric cell division and its relation to tumorigenesis is largely derived from studies on Drosophila neuroblasts NBs , where mutation of a single gene, brain tumor brat , was shown to alter asymmetric stem cell division in larval development, and to generate massive neoplastic growth and enlarged adult brain formed entirely of neoplastic NBs Caussinus and Gonzalez, ; Betschinger et al. Suppression of brat expression was used to establish a model of glioma stemness in Drosophila , where the upregulation of Notch, induced by reducing brat , was the critical node to maintain self-renewal and proper stemness Mukherjee et al.
This observation was also confirmed in glioblastomas where the human ortholog of brat , the tripartite motif-containing protein-3 TRIM3 , was shown to be necessary to suppress NOTCH1 signaling and to control stem cell activity during development to reduce tumor growth Chen et al.
We recently developed a neurogenic brain tumor model by impairing asymmetric cell division through the loss of function of lethal giant larvae lgl the Drosophila ortholog of Hugl-1 , in the type II NBs of the central brain Paglia et al. The development of correct animal model also for these tumors will be essential to develop specific treatments that can tackle these different brain tumors in vivo.
In the fruit fly, the circulatory system is open, the heart pumps the hemolymph into the body cavities and the exchange of gases takes place directly within the organs Medioni et al. Moreover, Drosophila is equipped with a complex branched system of interconnected tubules that is responsible for the oxygen transport, the tracheal system, an organ that is comparable in structure and function to the circulatory system of mammals Affolter et al.
In Drosophila 's epithelia, the induction of clones bearing lgl, Ras V 12 mutations identified how tumors are able to recruit vessels to oxygenate the growing mass Grifoni et al.
These tumor cells showed ectopic expression of Bnl branchless , the Drosophila homolog of Fibroblast Growth Factors FGFs, , and suffered from oxygen shortage hypoxia. In addition, it was observed a trans-differentiation of tumor cells into pseudo-tracheal cells with and the formation of new vessels, mimicking human FGF-mediated vascularization in cancer Grifoni et al.
Cell under hypoxia condition changes their cellular metabolism to favor growth, particularly in solid tumors Pavlova and Thompson, ; Vander Heiden and DeBerardinis, Fbw7 is known to inhibit tumor growth by targeting proteins to the proteasome pathways, and is mutated in a wide range of primary human cancers, this data suggests that its role as a tumor suppressor may be conserved also in the modulation of HIF-regulated angiogenesis in the tracheal system of the fly Mortimer and Moberg, This process of neo-tracheogenesis is now considered a novel cancer hallmark in fly, which may help to explore the relation between angiogenesis and tumor growth in humans Herranz et al.
Figure 3. Cancer cells form branched and tubule-shaped structures reproduced from Grifoni et al. The reconstruction along the z-axis shown in the upper part of the magnified images reveals a tubule-shaped structure encircling a lumen, indicating these cells are forming tracheal-like structures.
Lung cancer is a major cause of death in the world, and the standard therapeutic strategy used is chemotherapy because target therapies only decrease tumor growth and result in high toxicity. Recently, a new Drosophila lung cancer model was developed exploiting the tubular structure of the tracheal network Levine and Cagan, , and considered functionally and anatomically comparable to the vertebrate airways Andrew and Ewald, As a result, the cells of the tracheal branches over-proliferated to form tumors that ultimately killed the animals Levine and Cagan, This model was successfully used in a screen for chemical compounds approved by the Food and Drug Administration FDA , which resulted in the identification of several compounds able to reduce cell over-proliferation and to improve tracheal physiological functions Levine and Cagan, , further highlighting the strong potential of the use of fruit fly models for cancer-related chemical screens.
The prostate is an exocrine gland of the male reproductive system responsible for the maturation and production of the seminal fluid, with its activity depending on androgens mostly produced by the testis.
During organogenesis, the differentiation of the prostate's epithelium occurs along with that of stroma and depends on the complex coordination of many transcription factors and hormones that control the maturation of the quiescent organ Toivanen and Shen, The adult prostate epithelium has a low turnover rate and its hyperplasia characterizes the majority of benign prostatic tumors.
On the contrary, adenocarcinoma of the prostate is an aggressive tumor that rapidly progresses to a metastatic stage that can be partially blocked by androgen therapy Shiao et al. Studies on flies' male accessory gland revealed many parallels with the physiology of human prostate epithelium Wilson et al. Like in human prostate, Drosophila's accessory gland presents a secondary layer of epithelial cells that continue to proliferate; this homology allowed the development of models that mimic tumors of endocrine origin, including human prostate and thyroid adenomas Das and Cagan, , For example, the multiple endocrine neoplasia type 2 MEN2 syndrome, is characterized by different mutant-translocations involving the RET genes that result in multiple cancer phenotypes, including pheochromocytoma, parathyroid adenoma and the aggressive medullary thyroid carcinoma MTC Das and Cagan, A recent study demonstrated that the papillary carcinoma of the thyroid PTC , also caused by another genomic mutations of RET gene, can be profitably studied using the accessory gland of Drosophila to delineate and understand the mechanisms that characterize PTC in the context of the whole animal, including the relationship between tumor and normal cells in an environment that mimics tumor of endocrine origin in humans Levinson and Cagan, The prostate epithelium is characterized by the abundance of exosomes, microvesicles secreted from the endosomal multivesicular body MVB that fuse with sperm to modulate its activity and protect its homeostasis Wilson et al.
The exosomes are particularly relevant in cancer biology for their implication in tumor progression and survival, since they deliver survival factors, metabolites and miRNAs, that help creating a favorable microenvironment for cancer growth; in addition they also favor drug-resistance by activating mechanisms that favor the elimination of toxic chemicals such as chemotherapeutic products Ruivo et al.
Since the accessory gland has a similar structure as the prostate epithelium, characterized by the abundance of exosomes, it could be an optimal model to better study exosome biology in tumors of endocrine origins. The signaling pathways regulating blood cell differentiation are conserved from Drosophila to humans Lebestky et al. In addition, fly macrophages originate via self-renewal from progenitor cells localized in the lymph gland, a specialized hematopoietic organ that can be compared to the hematopoietic stem cell niche of the mammalian bone marrow Krzemien et al.
These similarities with vertebrate hematopoiesis outline the utility of using fly models to elucidate the basic mechanisms of hematopoietic differentiation and homeostasis responsible for severe diseases, including leukemia. Drosophila has already been used to study Acute Myeloid Leukemia AML , a widespread form of leukemia, and to identify the genes responsible for the disease. AML1 is a transcription factor, responsible for activating myeloid differentiation, which has a counterpart in the fly Sinenko et al.
In vertebrate tumors, the fusion of AML1 with the repressor ETO inhibits the differentiation of the multilineage progenitor cells, while their proliferation is activated, leading to AML1.
Interestingly, AML1 fused with ETO in Drosophila also causes the inhibition of hematopoietic cell differentiation, confirming that the fly is a good genetic model to study the mechanisms that drive leukemia in humans Osman et al. Myeloproliferative neoplasms MPNs have also been reproduced in the fly through gain-of-function mutations in the JAK pathway, finding a role for the downstream effector of the SWH pathway Yki in priming the expansion of Drosophila blood cells, which undergo malignant behavior following JAK activation Anderson et al.
The inflammatory response of cancer cells has been attributed to a response of the immune system to eradicate the tumor, but it can also be seen as a way to provide growth and survival, as inflammation contributes to genomic instability by releasing cytokines and through production of reactive oxygen species ROS that may induce genetic and genomic alterations Negrini et al. Normal cells detect and repair DNA damage, ensuring the maintenance of the correct number of chromosomes and tissue homeostasis, instead often cancer cells have increased mutation-rates leading to high chromosomal instability CIN that triggers aneuploidy and advances tumorigenesis Negrini et al.
Thus these opposite signaling pathways activated by TNF signals depend on the adaptor complexes recruited by the receptors and by the cellular context, and they may create a problem for the development of therapeutic strategies that target TNF signaling in tumors Ham et al.
Other studies highlighted the role of hemocytes in the interplay between inflammation and cancer, i. Using a similar model it was shown that Egr expression was higher in the hemocytes derived from cancer animals, and that its activity was necessary to stimulate invasive migration of tumor cells Cordero et al.
Work using allograft transplantation experiments, identify also a function for the hemocytes in tumor initiation, that is independent on Eiger, but relays rather on the activation by external stimuli i.
In summary, all these data suggest the existence of conserved mechanisms between the immune and tumor cells in flies that may recapitulate some of the most evolutionary conserved aspects described in cancer cells.
In tumor biology, evidences highlight the relevance of lipid metabolism in influencing tumor growth Katheder and Rusten, ; Weber et al. In this context, a recent role was identified for adipose triglyceride lipase ATGL whereby it hydrolyzes triacylglycerols into fatty acids FAs that may act as signaling molecules to induce growth both cell autonomously and in neighboring cells Walther and Farese, The contribution of ATGL to cancer growth is controversial, indeed several studies showed that its depletion reduced proliferation in colorectal cancer cells and in non-small-cell lung carcinoma Ou et al.
On the contrary, lack of ATGL favored pulmonary neoplasia in mice, and in few human tumors ATGL expression was found reduced highlighting the complex role of lipids in tumorigenesis Al-Zoughbi et al. Recent work associated the mechanism of lypolysis with the induction of autophagy, a mechanism used by the cells to re-cycle part of their cytoplasm or cellular content to survive when nutrients are reduced Dall'Armi et al.
The relevance in cancer of the link between lipids and autophagy was shown when ATGL-mediated lipolysis in a peritumoral area, increased autophagy and tumor survival using a non-autonomous mechanisms Martinez-Outschoorn et al. Interestingly, we observed that Myc in Drosophila induced autophagy in the fat body and this was enough to enhance survival of the whole animals upon starvation Parisi et al.
We linked this effect with the ability of Myc to increase desat1, a Stearoyl-CoA desaturase-1 SCD1 key enzyme in the synthesis of lipids, that we found co-expressed with Myc in human prostatic tumors Paiardi et al. Metabolic disorders and obesity are associated with cardiovascular disease and type II diabetes T2D , however numerous cohort studies reported that overweight people are more likely to develop certain types of cancer including endometrial, breast, liver, and ovarian cancer Cancer, ; Chen et al.
Obese people have often increased levels of circulating hormones like insulin that has been associated to higher levels of IGF-1 in colon, kidney, prostate and endometrial cancer Roberts et al. Another hormone, leptin, a cytokine produced by the adipocytes to control satiety in a signaling circuit of the brain, has also been found up-regulated in tissues from obese people, particularly in women post-menopause, and increased levels of leptin have been associated with higher incidence of breast and other tumors Ray, This low level of inflammation increases the levels of ROS and induces DNA and protein damage that may increase the risk of cancer Lafontan, ; Mraz and Haluzik, The role of the inflammatory response to combat infection and tissue injury, through the activation of the immune cells, is conserved also in Drosophila's circulating hemocytes Lemaitre and Hoffmann, , where most of the signals activated in the fat body results also in ROS production Dionne, ; Vlisidou and Wood, Indeed, we showed, using a genetic model that harbors an inflammation state in the fat body of larvae that mimic ATM, that reduction of ROS, using exogenous anti-oxidants components like flavonoids and anthiocianins, decreased hemocyte's migration and JNK activation in the cells of fat body Valenza et al.
Cancer stem cells CSCs have more features than tissue stem cells because they are able to initiate the tumor growth and fuel its maintenance and metastasis Malanchi et al.
In addition, CSCs are highly resistant to conventional therapy, both radiation and chemotherapy, and they are responsible for the recurrence of disease Mueller et al. Since the mechanisms underlying the ability of stem cells to support cancer progression are still unclear, Drosophila is convenient to use as it provides many tools for genetic and molecular investigations. Adult stem cells are required for tissue homeostasis and repair after injury and in adult flies, populations of stem cells are present in the posterior midgut, testis, and ovarian follicle rendering it again a good system to dissect these stem cell programs Hou and Singh, Drosophila was used to better understand the functions of the centrosome and microtubule-organizing center MTOC in the division of stem cells Tillery et al.
Drosophila and mammalian stem cells are similar and they are regulated by homologous signals corroborating the use of the fly in this field of tumor biology. CSCs can arise from normal stem cells whose long lifespan favors the accumulation of genetic mutations responsible for the malignant phenotype. The progression from normal progenitors to stem-like cancer cells was first explored in leukemia, although nowadays we know that several solid tumors such as brain, breast, lung and colon cancer originate from cells with stem features Krivtsov et al.
Several Drosophila models of stem cell tumors are now available, and a drug screening was successfully carried out highlighting several compounds active on the signaling promoting cancer growth Markstein et al.
Gain an understanding of the life cycle of D. Construct crosses of caught and known wild- type and mutated flies 6. Learn techniques to manipulate flies, sex them, and keep concise journal notes 7. Learn culturing techniques to keep the flies healthy 8.
Realize many science experiments cannot be conducted and concluded within one or two lab sessions. National standards covered in these lessons: Content: 1. Organisms require a set of instructions for specifying traits heredity 2. Hereditary information is located in genes.
Combinations of traits can describe the characteristics of an organism. Students goals: 1. Identify questions and concepts that guide scientific investigations 2. Design and conduct scientific investigations 3. Formulate and revise scientific explanations and models using logic and evidence 4. Communicate and defend a scientific argument. The genetics of Drosophila are well documented and several public-domain web sites feature the complete annotated genome.
Therefore, those teachers or students wishing to see where their mutations occur have a ready reference available. Since Drosophila has been so widely used in genetics, there are many different types of mutations available for purchase. In addition, the attentive student may find mutations within their own wild-caught cultures since, due to a short generation time, mutations are relatively common compared to other animal species.
This is the same as the well-known metamorphosis of butterflies. The larval stage has three instars, or molts. After the eggs hatch, small larvae should be visible in the growing medium. If your media is white, look for the small black area the mouth hooks at the head of the larvae. Some dried premixed media is blue to help identify larvae however this is not a necessity and with a little patience and practice, larvae are easily seen.
In addition, as the larvae feed they disrupt the smooth surface of the media and so by looking only at the surface one can tell if larvae are present. However, it is always a good idea to double check using a stereo microscope.
After the third instar, larvae will begin to migrate up the culture vial in order to pupate. Introduction In order to incorporate fruit flies in the classroom, it will be necessary to maintain cultures of flies for manipulation in crosses and as a backup for any mishaps which may occur.
Culturing is very easy and it is recommended to have students maintain their own cultures of flies. In that way, each student or group would be directly responsible for the care and long-term maintenance of the flies, including making large culture populations for their crosses. When directly involved, students gain proficiency and a greater understanding of the flies requirements and behavior. The teacher should remain as coach, not lecturer, assisting students in techniques. The instructor needs to maintain stock cultures of all strains and mutants used by students in case the aforementioned unforeseeable incident occurs and student cultures die out or become intermixed.
Losing cultures is the exception rather than the rule, and as long as students re-culture their flies on a regular basis and no mass contamination occurs, flies can be maintained for decades.
Bottles and vials Thomas Hunt Morgan used glass milk bottles for his experiments and, indeed, any container will do, including baby jars and assorted containers. However, for ease of culturing and transferring cultures, uniform bottles and vials are the best approach. Both can be purchased from a biological supply store. Bottles are used mainly for the maintenance of large populations of flies whereas culture vials are useful for maintaining smaller populations and are the preferred container for constructing student crosses.
If there is a desire to maintain stock cultures for a long period of time, or to reuse bottles and vials it is important completely clean and sterilize them. This is to prevent outbreaks of pests and diseases. To clean bottle and vials, first freeze them to kill any flies in them.
Bottles and vials can be purchased in a variety of sizes and materials. Glass is effective, however if dropped a student could lose 2 weeks of data in a single spill. Autoclaved sterile plastic vials are available and are preferable for student use. Vial sizes range from 96 mm by 25 mm to larger sizes, however the smaller size is recommended for making crosses and maintaining small cultures.
There are a variety of plugs available from soft cotton to foam plugs. This is a matter of preference and costs, however cotton works fine and can be bought at a local drug store in a pinch.
Fly food The first step in preparing culture vials is adding food media. There are a variety of types of food available for the flies; some require cooking and others are bought already prepared and dehydrated.
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