• cancer microenvironment
• prognostic markers

• Humans
• Female
• Tumor Microenvironment/immunology
• Breast Neoplasms/pathology
• Breast Neoplasms/immunology
• Disease Progression
• Cell Polarity/immunology
• Immune Tolerance
• Animals
• Immunosuppression Therapy

• P30 CA093373 NCI NIH HHS
• R01 CA213830 NCI NIH HHS
• RO1 CA213830 U.S. Department of Health & Human Services | NIH | National Cancer Institute (NCI)
• P30CA093373 U.S. Department of Health & Human Services | NIH | National Cancer Institute (NCI)
• U.S. Department of Health & Human Services | NIH | National Cancer Institute (NCI)
• UC Davis Immunology Pilot Grant Support

• Autophagy
• EMT
• LLGL2
• Proliferation
• Prostate cancer

• Animals
• Humans
• Male
• Mice
• Autophagy/physiology
• Autophagy/genetics
• Cell Line, Tumor
• Cell Movement/genetics
• Epithelial-Mesenchymal Transition/genetics
• Gene Silencing
• Mice, Nude
• Prostatic Neoplasms/pathology
• Prostatic Neoplasms/genetics
• Prostatic Neoplasms/metabolism
• Tumor Suppressor Proteins/genetics
• Tumor Suppressor Proteins/metabolism

• 2020R1A2C1014324 Ministry of Science and ICT, South Korea
• 2021R1A6A1A03045495 Ministry of Science and ICT, South Korea
• RS-2023-00246985 Ministry of Science and ICT, South Korea

• Drosophila
• lgl
• Arf79F
• Git
• Hippo pathway
• RtGEF
• V-ATPase
• Vap33

• Animals
• Adenosine Triphosphatases/metabolism
• Cell Polarity
• Drosophila/metabolism
• Drosophila melanogaster
• Drosophila Proteins/genetics
• Drosophila Proteins/metabolism
• Hippo Signaling Pathway
• Intracellular Signaling Peptides and Proteins/genetics
• Intracellular Signaling Peptides and Proteins/metabolism
• Neoplasms
• Protein Serine-Threonine Kinases/genetics
• Protein Serine-Threonine Kinases/metabolism
• Signal Transduction
• Tumor Suppressor Proteins/metabolism

• R01 GM123136 NIGMS NIH HHS
• GM123136 NIH HHS
• National Health and Medical Research Council
• Cancer Council Victoria
• Contributing to Australian Scholarship and Science Foundation
• National Institutes of Health
• La Trobe University

• apoptosis
• cancer evolution
• cell competition
• drosophila
• lethal (2) giant larvae

• D. melanogaster
• Keap1-Nrf2
• cancer biology
• cell polarity
• collective cell invasion
• computational biology
• follicle cells
• scRNA-seq
• systems biology
• transcriptomics

• Drosophila melanogaster model
• functional complementation
• genetic analysis
• heterologous rescue
• human genetic disorder

• Animals
• Drosophila/genetics
• Drosophila melanogaster/genetics
• Humans
• Phenotype
• Transgenes

Branching morphogenesis is a fundamental process by which organs in invertebrates and vertebrates form branches to expand their surface areas. The current dogma holds that directional cell migration determines where a new branch forms and thus patterns branching. Here, we asked whether mouse Lgl1, a homolog of the Drosophila tumor suppressor Lgl, regulates epithelial polarity in the mammary gland. Surprisingly, mammary glands lacking Lgl1 have normal epithelial polarity, but they form fewer branches. Moreover, we find that Lgl1 null epithelium is unable to directionally migrate, suggesting that migration is not essential for mammary epithelial branching as expected. We show that LGL1 binds to Integrin β1 and inhibits its downstream signaling, and Integrin β1 overexpression blocks epithelial migration, thus recapitulating the Lgl1 null phenotype. Altogether, we demonstrate that Lgl1 modulation of Integrin β1 signaling is essential for directional migration and that epithelial branching in invertebrates and the mammary gland is fundamentally distinct.

Ma et al. show that Lgl1 is essential for mammary gland branching morphogenesis but not epithelial polarity. Lgl1 is required for directional migration by regulating Integrin β1 signaling levels and focal adhesion strengths. Finally, branching mechanisms are distinct between mammary gland and Drosophila systems where directional migration is indispensable.

• branching morphogenesis
• collective migration
• epithelial migration
• epithelial polarity
• extracellular matrix
• integrin signaling
• tumor-suppressor genes

Vascular smooth muscle cell (VSMC) proliferation and migration contribute to neointimal hyperplasia after injury, which causes vascular remodeling related to arteriosclerosis, hypertension, and restenosis. Lethal giant larvae 1 (LGL1) is a highly conserved protein and plays an important role in cell polarity and tumor suppression. However, whether LGL1 affects neointimal hyperplasia is still unknown. In this study, we used smooth muscle-specific LGL1 knockout (LGL1^SMKO) mice generated by cross-breeding LGL1^flox/flox mice with α-SMA-Cre mice. LGL1 expression was significantly decreased during both carotid artery ligation in vivo and PDGF-BB stimulation in vitro. LGL1 overexpression inhibited the proliferation and migration of VSMCs. Mechanistically, LGL1 could bind with signal transducer and activator of transcription 3 (STAT3) and promote its degradation via the proteasomal pathway. In the carotid artery ligation animal model, smooth muscle-specific deletion of LGL1 accelerated neointimal hyperplasia, which was attenuated by the STAT3 inhibitor SH-4-54. In conclusion, LGL1 may inhibit neointimal hyperplasia by repressing VSMC proliferation and migration via promoting STAT3 proteasomal degradation.

Prostate cancer is the most common cancer in aging men. Despite recent progress, there are still few effective treatments to cure its aggressive and metastatic stages. A better understanding of the molecular mechanisms driving disease initiation and progression appears essential to support the development of more efficient therapies and improve patient care. To do so, multiple research models, such as cell culture and mouse models, have been developed over the years and have improved our comprehension of the biology of the disease. Recently, a new model has been added with the use of the Drosophila accessory gland. With a high level of conservation of major signaling pathways implicated in human disease, this functional equivalent of the prostate represents a powerful, inexpensive, and rapid in vivo model to study epithelial carcinogenesis. The purpose of this review is to quickly overview the existing prostate cancer models, including their strengths and limitations. In particular, we discuss how the Drosophila accessory gland can be integrated as a convenient complementary model by bringing new understanding in the mechanisms driving prostate epithelial tumorigenesis, from initiation to metastatic formation.

• Drosophila
• early tumorigenesis
• in vivo model
• late tumorigenesis
• prostate cancer

Notch is a conserved developmental signaling pathway that is dysregulated in many cancer types, most often through constitutive activation. Tumor cells with nuclear accumulation of the active Notch receptor, NICD, generally exhibit enhanced survival while patients experience poorer outcomes. To understand the impact of NICD accumulation during tumorigenesis, we developed a tumor model using the Drosophila ovarian follicular epithelium. Using this system we demonstrated that NICD accumulation contributed to larger tumor growth, reduced apoptosis, increased nuclear size, and fewer incidents of DNA damage without altering ploidy. Using bulk RNA sequencing we identified key genes involved in both a pre- and post- tumor response to NICD accumulation. Among these are genes involved in regulating double-strand break repair, chromosome organization, metabolism, like raptor, which we experimentally validated contributes to early Notch-induced tumor growth. Finally, using single-cell RNA sequencing we identified follicle cell-specific targets in NICD-overexpressing cells which contribute to DNA repair and negative regulation of apoptosis. This valuable tumor model for nuclear NICD accumulation in adult Drosophila follicle cells has allowed us to better understand the specific contribution of nuclear NICD accumulation to cell survival in tumorigenesis and tumor progression.

• Drosophila
• NICD
• Notch
• accumulation
• apoptosis
• epithelium
• follicle
• nuclear
• survival
• tumorigenesis

• cold-blooded cancer
• cooperative oncogenesis
• tumor/stroma interactions

• Animals
• Carcinogenesis
• Humans
• Membrane Proteins/genetics
• Membrane Proteins/metabolism
• Mutation
• Neoplasms/etiology
• Neoplasms/metabolism
• Neoplasms/pathology
• Signal Transduction
• Tumor Microenvironment
• Tumor Suppressor Proteins/genetics
• Tumor Suppressor Proteins/metabolism
• ras Proteins/genetics
• ras Proteins/metabolism

Lethal giant larvae (Lgl), scaffolding proteins, regulate the epithelial cell apicobasal polarity in Drosophila. They play important roles in asymmetric cell division, cell migration, and progenitor cells self-renewal as tumor suppressors. One of Lgl mammalian homologues proteins, LLGL2 overexpression has been reported in ER+ breast cancer and promotes tumor proliferation through regulating leucine uptake. Nonetheless, the role of LLGL2 in hepatocellular carcinoma (HCC) is still unknown.

TCGA dataset mining, qRT-PCR, Western blot along with immunohistochemistry assays were employed to explore LLGL2 expression in human HCC samples and cell lines. Moreover, the clinical value of LLGL2 was investigated in 156 HCC patients. Furthermore, the role as well as the molecular mechanism of LLGL2 in the progression of HCC was explored through a series of in vitro and in vivo experiments.

LLGL2 was up-regulated in HCC tissues, which was related with certain clinicopathological features including tumor number, vascular invasion as well as advanced stage. High expression of LLGL2 predicted poor prognosis after hepatectomy. LLGL2 promoted HCC cells proliferation, migration and invasion through PI3K/ATK signaling by promoting calcium ion influx.

Our study identified that LLGL2 is a tumor promoter in HCC for the first time, which could potentially be utilized as a new biomarker and a therapeutic target for HCC.

• Calcium influx
• Hepatocellular Carcinoma
• LLGL2
• PI3K/AKT signaling
• Progression

• Drosophila
• cilia
• disease model
• neoplasia
• neovascularization
• oxygen
• pharmacology
• polycystic kidney disease
• renal cell carcinoma

• Animals
• Carcinogenesis/genetics
• Carcinoma, Renal Cell/genetics
• Carcinoma, Renal Cell/pathology
• Cell Proliferation/genetics
• Disease Models, Animal
• Drosophila/genetics
• Gene Expression Regulation, Neoplastic/genetics
• Humans
• Kidney/metabolism
• Kidney/pathology
• Neovascularization, Pathologic/genetics
• Neovascularization, Pathologic/pathology
• Polycystic Kidney, Autosomal Dominant/genetics
• Polycystic Kidney, Autosomal Dominant/pathology
• Vascular Endothelial Growth Factor A/genetics

• IT10214 Mitacs
• Professional Development Award CUPFA

Human giant larvae-1 (Hugl-1) is a human homologue of Drosophila tumor suppressor lethal (2)-giant larvae and has been reported to be involved in the development of human malignancies. Previous studies performed by our group demonstrated that Hugl-1 inhibits glioma cell proliferation in an intracranial model of nude mice. However, the exact molecular mechanisms underlying the participation of Hugl-1 in glioma invasion and migration, and in the depolarizing process remain largely unknown. Utilizing the U251-MG cells with stable expression of Hugl-1, the present study used wound healing, Transwell invasion and western blot assays to explore the role and specific mechanism of Hugl-1 in glioma invasion and migration. The results of the present study demonstrated that overexpression of Hugl-1 decreased cell-cell adhesion and increased cell-cell extracellular matrix adhesion. In addition, overexpression of Hugl-1 promoted pseudopodia formation, glioma cell migration and invasion. The molecular mechanism of action involved the negative regulation of N-cadherin protein levels by Hugl-1. Overexpression or knockdown of N-cadherin partially suppressed or enhanced the effects of Hugl-1 on glioma cell migration and invasion, respectively. Furthermore, Hugl-1 inhibited cell proliferation, while promoting cell migration, which suggests that it may serve a two-sided biological role in cellular processes. Taken together, these results suggest that Hugl-1 promotes the migration and invasion of malignant glioma cells by decreasing N-cadherin expression. Thus, Hugl-1 may be applied in the development of targeted and personalized treatment.

• Hugl-1
• N-cadherin
• glioma
• invasion
• migration

Confusion over the concepts of “relationships” and “similarities” lies at the heart of many battles over the direction and intent of research projects. Here is a short story that demonstrates the difference between the two concepts: You look up at the clouds, and you begin to see the shape of a lion. The cloud has a tail, like a lion’s tale, and a fluffy head, like a lion’s mane. With a little imagination the mouth of the lion seems to roar down from the sky. You have succeeded in finding similarities between the cloud and a lion. If you look at a cloud and you imagine a tea kettle producing a head of steam and you recognize that the physical forces that create a cloud and the physical forces that produced steam from a heated kettle are the same, then you have found a relationship. Most popular classification algorithms operate by grouping together data objects that have similar properties or values. In so doing, they may miss finding the true relationships among objects. Traditionally, relationships among data objects are discovered by an intellectual process. In this chapter, we will discuss the scientific gains that come when we classify biological entities by relationships, not by their similarities.

• Goat
• association
• insertion/deletion (indel)
• litter size
• scribble cell polarity complex component (LLGL1)

• Cancer
• Drosophila
• Mary Stark
• Metastasis

Cancer is a multistep disease driven by the activation of specific oncogenic pathways concomitantly with the loss of function of tumor suppressor genes that act as sentinels to control physiological growth. The conservation of most of these signaling pathways in Drosophila, and the ability to easily manipulate them genetically, has made the fruit fly a useful model organism to study cancer biology. In this review we outline the basic mechanisms and signaling pathways conserved between humans and flies responsible of inducing uncontrolled growth and cancer development. 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.

• Drosophila cancer modeling
• cancer biology
• metabolism
• oncogene
• signaling
• therapeutic approaches
• tissue growth
• tumor suppressor

• Adenoma, Oxyphilic/drug therapy
• Adenoma, Oxyphilic/genetics
• Aminopyridines/pharmacology
• Animals
• Antineoplastic Agents/pharmacology
• Cell Line, Tumor
• Cell Proliferation/genetics
• Drosophila
• Electron Transport Complex I/antagonists & inhibitors
• Electron Transport Complex I/genetics
• Female
• Gene Knockout Techniques
• HCT116 Cells
• Humans
• Hypoxia-Inducible Factor 1, alpha Subunit/genetics
• Macrophages/immunology
• Metformin/pharmacology
• Mice
• Mice, Knockout
• Mice, Nude
• NADH Dehydrogenase/genetics
• Neovascularization, Pathologic/pathology
• Pyrroles/pharmacology
• Xenograft Model Antitumor Assays

• Wellcome Trust
• 14257 Cancer Research UK
• FC001112 Arthritis Research UK

• Drosophila
• MYC
• TSGs
• cell competition
• field cancerisation
• multifocality

• P40 OD018537 NIH HHS

• Llgl1
• TAZ
• epidermal growth factor receptor
• migration
• polarity

• Cell polarity
• Cell signaling
• Protein interactions
• Scribble module
• Tumourigenesis

Drosophila lethal giant larvae (lgl) encodes a conserved tumor suppressor with established roles in cell polarity, asymmetric division, and proliferation control. Lgl's human orthologs, HUGL1 and HUGL2, are altered in human cancers, however, its mechanistic role as a tumor suppressor remains poorly understood. Based on a previously established connection between Lgl and Fragile X protein (FMRP), a miRNA-associated translational regulator, we hypothesized that Lgl may exert its role as a tumor suppressor by interacting with the miRNA pathway. Consistent with this model, we found that lgl is a dominant modifier of Argonaute1 overexpression in the eye neuroepithelium. Using microarray profiling we identified a core set of ten miRNAs that are altered throughout tumorigenesis in Drosophila lgl mutants. Among these are several miRNAs previously linked to human cancers including miR-9a, which we found to be downregulated in lgl neuroepithelial tissues. To determine whether miR-9a can act as an effector of Lgl in vivo, we overexpressed it in the context of lgl knock-down by RNAi and found it able to reduce the overgrowth phenotype caused by Lgl loss in epithelia. Furthermore, cross-comparisons between miRNA and mRNA profiling in lgl mutant tissues and human breast cancer cells identified thrombospondin (tsp) as a common factor altered in both fly and human breast cancer tumorigenesis models. Our work provides the first evidence of a functional connection between Lgl and the miRNA pathway, demonstrates that miR-9a mediates Lgl's role in restricting epithelial proliferation, and provides novel insights into pathways controlled by Lgl during tumor progression.

Summary: Mir-9a overexpression can suppress the overgrowth phenotype caused by Lgl knock-down in epithelia. Gene profiling identifies pathways dysregulated in lgl mutants and shared features between flies and human cancer cells.

• Drosophila
• Epithelial growth
• miRNA

The Lethal giant larvae (Lgl) gene encodes a cortical cytoskeleton protein, Lgl, and is involved in maintaining cell polarity and epithelial integrity. Previously, we observed that Mgl-1, a mammalian homologue of the Drosophila tumor suppressor protein Lgl, is subjected to degradation via ubiquitin-proteasome pathway, and scaffolding protein RanBPM prevents the turnover of the Mgl-1 protein. Consequently, overexpression of RanBPM enhances Mgl-1-mediated cell proliferation and migration. Here, we analyzed the ability of ubiquitin-specific protease 11 (USP11) as a novel regulator of Mgl-1 and it requires RanBPM to regulate proteasomal degradation of Mgl-1. USP11 showed deubiquitinating activity and stabilized Mgl-1 protein. However, USP11-mediated Mgl-1 stabilization was inhibited in RanBPM-knockdown cells. Furthermore, in the cancer cell migration, the regulation of Mgl-1 by USP11 required RanBPM expression. In addition, an in vivo study revealed that depletion of USP11 leads to tumor formation. Taken together, the results indicated that USP11 functions as a tumor suppressor through the regulation of Mgl-1 protein degradation via RanBPM.

• RanBPM
• UAF1
• USP11
• deubiquitinating enzyme
• ubiquitin

• Animals
• Brain Neoplasms/genetics
• Brain Neoplasms/pathology
• Carcinogenesis/genetics
• Cell Differentiation/genetics
• Cell Polarity/genetics
• Disease Models, Animal
• Drosophila Proteins/genetics
• Drosophila melanogaster/genetics
• Glioblastoma/genetics
• Glioblastoma/pathology
• Humans
• Neural Stem Cells/metabolism
• Neural Stem Cells/pathology
• Neurogenesis/genetics
• PTEN Phosphohydrolase/genetics
• Protein Kinase C/genetics
• Signal Transduction/genetics
• Tumor Suppressor Proteins/genetics

• Lgl1
• NSCLC
• metastasis
• miR-652-3p
• proliferation

• Cancer
• Cell polarity
• Dlg
• Lgl
• PCP
• Planar cell polarity
• Scribble
• Signaling

• Carcinogenesis/genetics
• Cell Communication/genetics
• Cell Line, Tumor
• Cell Proliferation/genetics
• Gene Expression Regulation, Neoplastic
• Genetic Heterogeneity
• Humans
• Neoplasms/genetics
• Neoplasms/pathology
• Proto-Oncogene Proteins c-myc/genetics

• Cancer
• Drosophila
• Drug screening
• Genetic screening
• Invasion
• Metastasis
• Oncogene
• Personalized medicine
• Polypharmacology
• Tumor-suppressor gene

• Animals
• Drosophila
• Drosophila melanogaster
• Humans
• Mammals
• Models, Genetic
• Neoplasms
• Signal Transduction

• Gliomas
• Hippo
• Hugl-1
• Proliferation

• Animals
• Astrocytoma/pathology
• Brain Neoplasms/pathology
• Cell Line, Tumor
• Cell Proliferation/physiology
• Cytoskeletal Proteins/genetics
• Cytoskeletal Proteins/metabolism
• Disease Models, Animal
• Female
• Gene Expression Regulation, Neoplastic/genetics
• Gene Expression Regulation, Neoplastic/physiology
• Green Fluorescent Proteins/genetics
• Green Fluorescent Proteins/metabolism
• Humans
• Ki-67 Antigen/metabolism
• Male
• Mice
• Mice, Nude
• Phenylurea Compounds/metabolism
• Sincalide/metabolism
• Transfection

Lgl is a conserved tumor suppressor suggested to be involved in cell polarity regulation and suppression of cell proliferation. Lgl inhibits formation of the VprBP-DDB1-Cul4A-Roc1 ubiquitin E3 ligase complex, which is implicated in cell cycle progression, by promoting formation of the Lgl-VprBP-DDB1 complex to prevent overproliferation.

Lethal giant larvae (Lgl) is an evolutionarily conserved tumor suppressor whose loss of function causes disrupted epithelial architecture with enhanced cell proliferation and defects in cell polarity. A role for Lgl in the establishment and maintenance of cell polarity via suppression of the PAR-aPKC polarity complex is established; however, the mechanism by which Lgl regulates cell proliferation is not fully understood. Here we show that depletion of Lgl1 and Lgl2 in MDCK epithelial cells results in overproliferation and overproduction of Lgl2 causes G1 arrest. We also show that Lgl associates with the VprBP-DDB1 complex independently of the PAR-aPKC complex and prevents the VprBP-DDB1 subunits from binding to Cul4A, a central component of the CRL4 [VprBP] ubiquitin E3 ligase complex implicated in G1- to S-phase progression. Consistently, depletion of VprBP or Cul4 rescues the overproliferation of Lgl-depleted cells. In addition, the affinity between Lgl2 and the VprBP-DDB1 complex increases at high cell density. Further, aPKC-mediated phosphorylation of Lgl2 negatively regulates the interaction between Lgl2 and VprBP-DDB1 complex. These results suggest a mechanism protecting overproliferation of epithelial cells in which Lgl plays a critical role by inhibiting formation of the CRL4 [VprBP] complex, resulting in G1 arrest.

Polarity protein complexes are crucial for epithelial apical–basal polarity and directed cell migration. Since alterations of these processes are common in cancer, polarity proteins have been proposed to function as tumor suppressors or oncogenic promoters. Here, we review the current understanding of polarity protein functions in epithelial homeostasis, as well as tumor formation and progression. As most previous studies focused on the function of single polarity proteins in simplified model systems, we used a genomics approach to systematically examine and identify the expression profiles of polarity genes in human cancer. The expression profiles of polarity genes were distinct in different human tissues and classified cancer types. Additionally, polarity expression profiles correlated with disease progression and aggressiveness, as well as with identified cancer types, where specific polarity genes were commonly altered. In the case of Scribble, gene expression analysis indicated its common amplification and upregulation in human cancer, suggesting a tumor promoting function.

• breast cancer
• cancer genomics
• glioblastoma multiforme
• polarity proteins

Angiogenesis is the term used to describe all the alterations in blood vessel growth induced by a tumour mass following hypoxic stress. The occurrence of multiple strategies of vessel recruitment favours drug resistance, greatly complicating the treatment of certain tumours. In Drosophila, oxygen is conveyed to the internal organs by the tracheal system, a closed tubular network whose role in cancer growth is so far unexplored. We found that, as observed in human cancers, Drosophila malignant cells suffer from oxygen shortage, release pro-tracheogenic factors, co-opt nearby vessels and get incorporated into the tracheal walls. We also found that the parallelisms observed in cellular behaviours are supported by genetic and molecular conservation. Finally, we identified a molecular circuitry associated with the differentiation of cancer cells into tracheal cells. In summary, our findings identify tracheogenesis as a novel cancer hallmark in Drosophila, further expanding the power of the fly model in cancer research.

Cell polarity is one of the most basic properties of all normal cells and is essential for regulating numerous biological processes. Loss of polarity is considered a hallmark for cancer. Multiple polarity proteins are implicated in maintenance of cell polarity. Lethal (2) giant larvae (Lgl) is one of polarity proteins that plays an important role in regulating cell polarity, asymmetric division as well as tumorigenesis. Lgl proteins in different species have similar structures and conserved functions. Lgl acts as an indispensable regulator of cell biological function, including cell polarity and asymmetric division, through interplaying with other polarity proteins, regulating exocytosis, mediating cytoskeleton and being involved in signaling pathways. Furthermore, Lgl plays a role of a tumor suppressor, and the aberrant expression of Hugl, a human homologue of Lgl, contributes to multiple cancers. However, the exact functions of Lgl and the underlying mechanisms remain enigmatic. In this review, we will give an overview of the Lgl functions in cell polarity and cancer development, discuss the potential mechanisms underlying these functions, and raise our conclusion of previous studies and points of view about the future studies.

• asymmetric division
• cell polarity
• lethal (2) giant larvae
• tumor suppression

Glioblastoma multiforme is an aggressive and incurable type of brain tumor. A subset of undifferentiated glioblastoma cells, known as glioblastoma tumor initiating cells (GTICs), has an essential role in the malignancy of this disease and also appears to mediate resistance to radiation therapy and chemotherapy. GTICs retain the ability to differentiate into cells with reduced malignant potential, but the signaling pathways controlling differentiation are not fully understood at this time. PTEN loss is a very common in glioblastoma multiforme and leads to aberrant activation of the phosphoinositide 3-kinase pathway. Increased signalling through this pathway leads to activation of multiple protein kinases, including atypical protein kinase C. In Drosophila, active atypical protein kinase C has been shown to promote the self-renewal of neuroblasts, inhibiting their differentiation along a neuronal lineage. This effect is mediated by atypical protein kinase c-mediated phosphorylation and inactivation of Lgl, a protein that was first characterized as a tumour suppressor in Drosophila. The effects of the atypical protein kinase C/Lgl pathway on the differentiation status of GTICs, and its potential link to PTEN loss, have not been assessed previously. Here we show that PTEN loss leads to the phosphorylation and inactivation of Lgl by atypical protein kinase C in glioblastoma cells. Re-expression of PTEN in GTICs promoted their differentiation along a neuronal lineage. This effect was also seen when atypical protein kinase C was knocked down using RNA interference, and when a non-phosphorylatable, constitutively active form of Lgl was expressed in GTICs. Thus PTEN loss, acting via atypical protein kinase C activation and Lgl inactivation, helps to maintain GTICs in an undifferentiated state.

The dsRNA binding protein (dsRBP) PACT was first described as an activator of the dsRNA dependent protein kinase PKR in response to stress signals.  Additionally, it has been identified as a component of the small RNA processing pathway.  A role for PACT in this pathway represents an important interplay between two modes of post-transcriptional gene regulation.  The function of PACT in this context is poorly understood.  Thus, additional approaches are required to clarify the mechanism by which PACT functions.  In this study, the genetic utility of  Drosophila melanogaster was employed to identify dsRNA-binding proteins that are functionally orthologous to PACT.  Transgenic  Drosophila expressing human PACT were generated to determine whether PACT is capable of functionally substituting for the  Drosophila dsRBP R2D2, which has a well-defined role in small RNA biogenesis.  Results presented here indicate that PACT is unable to substitute for R2D2 at the whole organism level.

• P01 CA062220 NCI NIH HHS

In epithelial and stem cells, lethal giant larvae (Lgl) is a potent tumour suppressor, a regulator of Notch signalling, and a mediator of cell fate via asymmetric cell division. Recent evidence suggests that the function of Lgl is conserved in mammalian haematopoietic stem cells and implies a contribution to haematological malignancies. To date, direct measurement of the effect of Lgl expression on malignancies of the haematopoietic lineage has not been tested. In Lgl1^−/− mice, we analysed the development of haematopoietic malignancies either alone, or in the presence of common oncogenic lesions. We show that in the absence of Lgl1, production of mature white blood cell lineages and long-term survival of mice are not affected. Additionally, loss of Lgl1 does not alter leukaemia driven by constitutive Notch, c-Myc or Jak2 signalling. These results suggest that the role of Lgl1 in the haematopoietic lineage might be restricted to specific co-operating mutations and a limited number of cellular contexts.

• Animals
• Bone Marrow Transplantation
• Cell Lineage/physiology
• Cytoskeletal Proteins
• DNA Primers/genetics
• Disease Models, Animal
• Hematopoietic Stem Cells/metabolism
• Homeodomain Proteins/genetics
• Homeodomain Proteins/metabolism
• Kaplan-Meier Estimate
• Leukemia, B-Cell/metabolism
• Leukemia, T-Cell/metabolism
• Mice
• Mice, Knockout
• Real-Time Polymerase Chain Reaction
• Reverse Transcriptase Polymerase Chain Reaction
• Tumor Suppressor Proteins/genetics
• Tumor Suppressor Proteins/metabolism

AIM: To determine whether the human giant larvae homolog 1 gene (Hugl-1/Llg1/Lgl1) exerts tumor suppressor effects in esophageal cancer.

METHODS: We constructed a Hugl-1 expression plasmid, pEZ-M29-Hugl1, for gene transfection. We transfected the pEZ-M29-Hugl1 plasmid into Eca109 esophageal cancer cell lines with Lipofectamine 2000 to overexpress Hugl-1. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were performed to determine the effects of the plasmid on Hugl-1 expression. In vitro cell proliferation and apoptosis were examined separately by cell counting Kit-8 (CCK-8) assay, flow cytometry, and Western blotting before and after the transfection of the plasmid into Eca109 cells. Cell cycle distribution was assessed with flow cytometry. The effect of Hugl-1 overexpressing on tumor growth in vivo was performed with a xenograft tumor model in nude mice. Expression of Hugl-1 in xenograft tumor was analyzed by immunohistochemistry. The transferase-mediated dUTP nick end-labeling (TUNEL) technique was performed to detect and quantitate apoptotic cell.

RESULTS: The transfection efficiency was confirmed with real-time RT-PCR and Western blotting. Our results show that compared with control groups the mRNA levels and protein levels of Hugl-1 in pEZ-M29-Hugl1-treated group were remarkably increased (P < 0.05). The CCK-8 assay demonstrated that the growth of cells overexpressing Hugl-1 was significantly lower than control cells. Cell cycle distribution showed there was a G₀/G₁ cell cycle arrest in cells overexpressing Hugl-1 (64.09% ± 3.14% vs 50.32% ± 4.60%, 64.09% ± 3.14% vs 49.13% ± 2.24%). Annexin V-fluorescein isothiocyanate revealed that apoptosis was significantly increased in cells overexpressing Hugl-1 compared with control group (17.33% ± 4.76% vs 6.90% ± 1.61%, 17.33% ± 4.76% vs 6.27% ± 0.38%). Moreover, we found that Hugl-1 changes the level of the anti-apoptotic protein Bcl-2 and the pro-apoptotic protein Bax and the activation of both caspase-3 and caspase-9. With a TUNEL assay, we found that Hugl-1 markedly increased the apoptosis rate of Eca109 cells in vivo (60.50% ± 9.11% vs 25.00% ± 12.25%). It was shown that Hugl-1 represents a significantly more effective tumor suppressor gene alone in a xenograft tumor mouse model. This data suggest that Hugl-1 inhibited tumor growth and induced cell apoptosis in vivo.

CONCLUSION: These results suggest that Hugl-1 induces growth suppression and apoptosis in a human esophageal squamous cell carcinoma cell line both in vitro and in vivo.

• Esophageal squamous cell carcinoma
• Human giant larvae homolog 1
• Proliferation
• Apoptosis

• Animals
• Apoptosis
• Apoptosis Regulatory Proteins/metabolism
• Carcinoma, Squamous Cell/genetics
• Carcinoma, Squamous Cell/metabolism
• Carcinoma, Squamous Cell/pathology
• Cell Cycle
• Cell Line, Tumor
• Cell Proliferation
• Cytoskeletal Proteins/genetics
• Cytoskeletal Proteins/metabolism
• Esophageal Neoplasms/genetics
• Esophageal Neoplasms/metabolism
• Esophageal Neoplasms/pathology
• Gene Expression Regulation, Neoplastic
• Humans
• Mice
• Mice, Inbred BALB C
• Mice, Nude
• Time Factors
• Transfection
• Tumor Burden
• Up-Regulation

• EMT
• Par3
• Par6
• RhoA
• Smurf1
• TGFβ
• aPKC
• cell polarity

Stem and progenitor cells are characterized by their ability to self-renew and produce differentiated progeny. A fine balance between these processes is achieved through controlled asymmetric divisions and is necessary to generate cellular diversity during development and to maintain adult tissue homeostasis. Disruption of this balance may result in premature depletion of the stem/progenitor cell pool, or abnormal growth. In many tissues, including the brain, dysregulated asymmetric divisions are associated with cancer. Whether there is a causal relationship between asymmetric cell division defects and cancer initiation is as yet not known. Here, we review the cellular and molecular mechanisms that regulate asymmetric cell divisions in the neural lineage and discuss the potential connections between this regulatory machinery and cancer.

• breast cancer
• cell junction
• differentiation
• epigenetics
• mammary epithelial cell
• polarity

• Animals
• Breast Neoplasms/metabolism
• Breast Neoplasms/physiopathology
• Cell Polarity/physiology
• Epigenomics
• Epithelial Cells/physiology
• Female
• Humans
• Intercellular Junctions/physiology
• Membrane Proteins/physiology