Ras Superfamily Of GTPases Research Articles

PO-220 RAN, a novel and promising gene for malignant pleural mesothelioma

IntroductionRAN is a member of RAS superfamily of GTPases involved in a varied range of cellular processes. Although it is widely demonstrated RAN is overexpressed in many human tumours having an essential role in malignant cell survival and cancer progression, little is known about its role in Malignant Pleural Mesothelioma (MPM). Previous studies showed the RAN gene is upregulated in mesothelioma tissues and cell lines, so it might be involved in carcinogenesis of MPM. We aimed to explore the functional role of RAN in MPM cell lines and its likely use as co-target in mesothelioma treatment.Material and methodsThe role of RAN in MPM tumorigenesis was investigated through RNA interference, on a panel of one mesothelial cell line (Met-5A) and four MPM cell lines (Mero-14, Mero-25, Istmes-2 and NCI-H28). After monitoring gene knockdown, at both the mRNA and protein levels, a phenotypic study was performed through Caspase-3/7, Sulforhodamine B, Wound-Healing and Colony Formation assays. Flow cytometry was employed to monitor cell cycle. To validate data from siRNA experiments, two different siRNA were independently used to target RAN. The gene was also knocked-out using a lentiviral CRISPR/Cas9 system in Mero-14. Cas9 endonuclease and gRNA were transduced by two different lentiviral transfer vectors.The doxycycline-regulated Cas9 induction was followed by DNA, RNA and proteins extraction to confirm the occurrence of gene disruption. TIDE analysis was carried out to monitor targeted mutations triggered by the genome editing.Results and discussionsThe siRNA-mediated knockdown was confirmed at both the mRNA and protein level in all cell lines. The silencing caused a statistically significant decrease of proliferation rate and clonogenicity in Mero-14, Mero-25 and Istmes-2.The migration ability was affected in Met-5A and Istmes-2. An increase in apoptosis was observed in all cell lines, being statistically significant only in the malignant ones. Flow cytometry analysis showed an increase of cells in G0/G1 phase and a decrease of cells in S phase, being significant in Mero-14 cell line only. RAN knock-out has been confirmed at both the mRNA and protein level, whereas the TIDE analysis is still ongoing.ConclusionThis study showed that MFAP5 is a novel myoepithelial cell marker that appears to be up-regulated in duct epithelium in DCIS and IC-NST during tumourogenesis and that its cytoplasmic expression in invasive tumours seems to have apoor prognostic role manifested by its association with poor prognostic parameters such as high grade, late stage,lymph node invasion and increased MVD.

Abstract 5515: Ras-like estrogen-regulated growth-inhibitory gene (RERG): A novel biomarker and potential therapeutic target for women with lung cancer

Abstract Background: Lung cancer is the second most common cancer diagnosed in women. In fact, twice as many women will die from lung cancer compared to breast cancer, the key risk factor being tobacco use. Hence, there is a need to identify new molecular biomarkers to aid in early detection and develop new therapeutic strategies in tobacco-related lung cancer. Ras-like Estrogen-Regulated Growth-Inhibitory Gene (RERG) is a member of the Ras superfamily of GTPases that play an important role in cellular processes such as proliferation, differentiation, and apoptosis. Unlike other members of the Ras superfamily members of proto-oncogenes, RERG functions as a tumor suppressor. Objective: To investigate the utility of RERG expression as a novel biomarker and a potential therapeutic target in lung cancer. Results: In silico analysis of The Cancer Genome Atlas (TCGA) lung cancer datasets revealed a significant downregulation of RERG expression in lung tumors. Furthermore, reduced expression of RERG in lung tumors was also observed to be correlated with poor prognosis as determined by Kaplan-Meier survival analysis. Evaluation of formalin-fixed, paraffin-embedded (FFPE) human lung cancer tissues and fresh frozen lung tumor tissues corroborated our in silico observations. Most notably, tobacco smoke was identified to be associated with decreased RERG expression in lung tumors. The most intriguing observation from this study is the significant decrease of RERG expression in female smokers as a result of promoter hypermethylation. Conclusion: Taken together, these findings suggest that RERG may represent a potential biomarker in lung cancer, particularly among smokers. Further investigation would focus on the mechanism of RERG loss and its influence on lung tumor development, particularly in female smokers. Citation Format: Michelle Van Scoyk, Sreedevi Avasarala, Pei-Ying Wu, Yanlin Su, Lane Lerner, Alicia Hulbert, Kamesh Bikkavilli, Robert A. Winn. Ras-like estrogen-regulated growth-inhibitory gene (RERG): A novel biomarker and potential therapeutic target for women with lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5515.

Comparative phylogenetic and expression analysis of small GTPases families in legume and non-legume plants

ABSTRACTBackground: Small monomeric GTPases act as molecular switches in several processes that involve polar cell growth, participating mainly in vesicle trafficking and cytoskeleton rearrangements. This gene superfamily has largely expanded in plants through evolution as compared with other Kingdoms, leading to the suggestion that members of each subfamily might have acquired new functions associated to plant-specific processes. Legume plants engage in a nitrogen-fixing symbiotic interaction with rhizobia in a process that involves polar growth processes associated with the infection throughout the root hair. To get insight into the evolution of small GTPases associated with this process, we use a comparative genomic approach to establish differences in the Ras GTPase superfamily between legume and non-legume plants.Results: Phylogenetic analyses did not show clear differences in the organization of the different subfamilies of small GTPases between plants that engage or not in nodule symbiosis. Protein alignments revealed a strong conservation at the sequence level of small GTPases previously linked to nodulation by functional genetics. Interestingly, one Rab and three Rop proteins showed conserved amino acid substitutions in legumes, but these changes do not alter the predicted conformational structure of these proteins. Although the steady-state levels of most small GTPases do not change in response to rhizobia, we identified a subset of Rab, Rop and Arf genes whose transcript levels are modulated during the symbiotic interaction, including their spatial distribution along the indeterminate nodule.Conclusions: This study provides a comprehensive study of the small GTPase superfamily in several plant species. The genetic program associated to root nodule symbiosis includes small GTPases to fulfill specific functions during infection and formation of the symbiosomes. These GTPases seems to have been recruited from members that were already present in common ancestors with plants as distant as monocots since we failed to detect asymmetric evolution in any of the subfamily trees. Expression analyses identified a number of legume members that can have undergone neo- or sub-functionalization associated to the spatio-temporal transcriptional control during the onset of the symbiotic interaction.

The Differential Expression and Possible Function of Long Noncoding RNAs in Liver Cells Infected by Dengue Virus.

The function of long noncoding RNAs (lncRNAs) in liver injury resulted by dengue virus (DENV) infection have not yet been explored. The differential expression profiles of lncRNAs (as well as mRNAs) in the L-02 liver cells infected by DENV1, DENV2, or uninfected were compared and analyzed after a high throughput RNA seq. The significantly up-regulated and down-regulated lncRNAs (or mRNAs) resulted by DENV infection were identified with a cutoff value at log2 (ratio) ≥ 1.5 and log2 (ratio) ≤ -1.5 (ratio = the reads of the lncRNAs or mRNAs from the infection groups divided by the reads from the control group). Several differentially expressed lncRNAs were verified with reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Target gene analysis, pre-miRNA prediction, and the lncRNA-mRNA co-expression network construction were performed to predict the function of the differentially expressed lncRNAs. The differentially expressed lncRNAs were associated with biosynthesis, DNA/RNA related processes, inhibition of estrogen signaling pathway, sterol biosynthetic process, protein dimerization activity, vesicular fraction in DENV1 infection group; and with protein secretion, methyltransferase process, host cell cytoskeleton reorganization and the small GTPase Ras superfamily, inhibition of cell proliferation, induction of apoptosis in DENV2 infection. LncRNAs might be novel diagnostic markers and targets for further researches on dengue infection and liver injury resulted by dengue virus.

To finish things well: cysteine methylation ensures selective GTPase membrane localization and signalling.

Isoprenylcysteine-O-Carboxyl Methyltransferase (ICMT) catalyzes the final step in the prenylation process of different proteins including members of the Ras superfamily of GTPases. While cysteine methylation is essential in mammalian cells for growth, membrane association, and signalling by Ras and Rho GTPases, its role during signal transduction events in simple eukaryotes like yeasts appears irrelevant. By using a multidisciplinary approach our group has recently shown that, contrary to this initial assumption, in the fission yeast Schizosaccharomyces pombe ICMT activity encoded by the Mam4 gene is not only important to promote selective plasma membrane targeting of Ras and specific Rho GTPases, but also to allow precise downstream signalling to the mitogen-activated protein kinase and target of rapamycin pathways in response to diverse environmental cues. Thus, the dynamic regulation of in vivo methylation as a modulator of GTPase localization and function is an evolutionary conserved mechanism, making fission yeast an appealing model organism to study the regulation of this process.

Abstract 5523: Loss of RAB25 cooperates with oncogenes in the transformation of human mammary epithelial cells

Abstract The RAB guanosine triphosphates (RAS-related in brain) belong to the Ras superfamily of GTPases, and loss of RAB 25 expression has been reported in a number of breast cancer cases containing H-Ras point mutations, particularly triple negative breast cancers (TNBC), one of the most aggressive subtypes of breast cancer and associated with a poor prognosis. The mechanism involved in the progression of these tumors is poorly understood. In this study, we are trying to understand if loss of RAB25 expression in Human Mammary Epithelial Cell (HMEC) lines co-operates with H-Ras mutations and contributes to tumorigenesis. HMEC were immortalized by transduction with LXSN CDK4 R24C, a mutant form of cyclin-dependent kinase, followed by transduction with hTERT, catalytic subunit of the telomerase enzyme that permits the cells to exceed the Hayflick Limit and become immortal. We have found that with loss of RAB25 and over expression of mutant H-Ras61L, immortal HMEC undergo transformation. We have looked into the co-operativity between loss of Rab25 and H-Ras61L mutant by in-vitro studies to show their anchorage independent growth and increased ability to migrate. Furthermore, cells express low CD24, high CD44, and very low levels of Claudin indicating that cells acquire stem-like properties upon transformation. Loss of RAB25 and over-expression of H-ras61L resulted in increased expression of transcription markers Snail and Slug that drive these cells to lose E-cadherin and undergo Epithelial Mesenchymal Transition (EMT). We also intend to carry out nude mice studies to look for the potential of these cells to form tumors and metastasize. This study shows that loss of RAB25 and over-expression of mutant H-Ras can transform HMEC and give rise to mesenchymal stem-like tumors. Our findings reveal that RAB25 functions as a tumor suppressor gene, and loss of RAB25 could serve as a novel biomarker in the prognosis of Claudin-low type of TNBC. Citation Format: Krishna Rao, Pooja Sridhar Joshi. Loss of RAB25 cooperates with oncogenes in the transformation of human mammary epithelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5523. doi:10.1158/1538-7445.AM2017-5523

Molecular mechanism of activation of class IA phosphoinositide 3-kinases (PI3Ks) by membrane-localized HRas

Class IA PI3Ks are involved in the generation of the key lipid signaling molecule phosphatidylinositol 3,4,5-trisphosphate (PIP3), and inappropriate activation of this pathway is implicated in a multitude of human diseases, including cancer, inflammation, and primary immunodeficiencies. Class IA PI3Ks are activated downstream of the Ras superfamily of GTPases, and Ras-PI3K interaction plays a key role in promoting tumor formation and maintenance in Ras-driven tumors. Investigating the detailed molecular events in the Ras-PI3K interaction has been challenging because it occurs on a membrane surface. Here, using maleimide-functionalized lipid vesicles, we successfully generated membrane-resident HRas and evaluated its effect on PI3K signaling in lipid kinase assays and through analysis with hydrogen-deuterium exchange MS. We screened all class IA PI3K isoforms and found that HRas activates both p110α and p110δ isoforms but does not activate p110β. The p110α and p110δ activation by Ras was synergistic with activation by a soluble phosphopeptide derived from receptor tyrosine kinases. Hydrogen-deuterium exchange MS revealed that membrane-resident HRas, but not soluble HRas, enhances conformational changes associated with membrane binding by increasing membrane recruitment of both p110α and p110δ. Together, these results afford detailed molecular insight into the Ras-PI3K signaling complex, provide a framework for screening Ras inhibitors, and shed light on the isoform specificity of Ras-PI3K interactions in a native membrane context.

A thirty-year quest for a role of R-Ras in cancer: from an oncogene to a multitasking GTPase

Since the identification of R-Ras, which is the first Ras-related GTPase isolated based on sequence similarity to the classical RAS oncogene, more than 160 members of the Ras superfamily of GTPases have been identified and classified into the Ras, Rho, Rap, Rab, Ran, Arf, Rheb, RGK, Rad, Rit, and Miro subfamilies. R-Ras belongs to the Ras subfamily of small G-proteins, which are frequently implicated in cell growth and differentiation. Although the roles of R-Ras in cellular transformation and integrin-mediated cell adhesion have been extensively studied, the physiological function of this enigmatic G-protein was only revealed when a mouse strain deficient in R-Ras was generated. In parallel, a plethora of research findings also linked R-Ras with processes including tumor angiogenesis, axon guidance, and immune cell trafficking. Several upstream factors that modulate R-Ras GTP-binding were identified including Notch, semaphorin, and chemokine C-C motif ligand 21. A review of our evolving understanding of the role of R-Ras in oncogenesis is timely, as this year marks the 30th anniversary of the publication describing the cloning of R-Ras.

Design and purification of active truncated phosphoinositide 3-kinase gamma protein constructs for structural studies

Phosphoinositide 3-kinase gamma (PI3Kγ) is a lipid kinase that plays a crucial role in cell migration, chemotaxis, oxidative burst and myocardial contractility. It is activated downstream of G protein-coupled receptors (GPCRs) and small GTPases of Ras superfamily. PI3Kγ is a heterodimer composed of a catalytic and a regulatory subunit that is expressed mostly in hematopoietic cells and in the heart. Although it has attracted a lot of attention because of its link with tumor inflammation and heart diseases, its regulation is still not fully understood. This can be attributed to the absence of high-resolution structural details of the PI3Kγ heterodimer. Here we describe the design and purification of PI3Kγ constructs where flexible loops in the regulatory subunit have been removed based on structural information obtained by hydrogen/deuterium exchange – mass spectrometry (HDX-MS). The soluble constructs retain both basal activity and sensitivity to GPCR stimulation, and are thus an optimal tool to further explore their regulation using a structure-based approach.

Nucleotide Dependent Switching in Rho GTPase: Conformational Heterogeneity and Competing Molecular Interactions

Ras superfamily of GTPases regulate myriad cellular processes through a conserved nucleotide (GTP/GDP) dependent switching mechanism. Unlike Ras family of GTPases, for the Rho GTPases, there is no clear evidence for the existence of “sub-states” such as state 1 & state 2 in the GTP bound form. To explore the nucleotide dependent conformational space of the Switch I loop and also to look for existence of state 1 like conformations in Rho GTPases, atomistic molecular dynamics and metadynamics simulations on RhoA were performed. These studies demonstrate that both the nucleotide-free state and the GDP bound “OFF” state have very similar conformations, whereas the GTP bound “ON” state has unique conformations with signatures of two intermediate states. The conformational free energy landscape for these systems suggests the presence of multiple intermediate states. Interestingly, the energetic penalty of exposing the non-polar residues in the GTP bound form is counter balanced by the favourable hydrogen bonded interactions between the γ-phosphate group of GTP with the highly conserved Tyr34 and Thr37 residues. These competing molecular interactions lead to a tuneable energy landscape of the Switch I conformation, which can undergo significant changes based on the local environment including changes upon binding to effectors.

Discovery of Rab1 binding sites using an ensemble of clustering methods.

Targeting non-native-ligand binding sites for potential investigative and therapeutic applications is an attractive strategy in proteins that share common native ligands, as in Rab1 protein. Rab1 is a subfamily member of Rab proteins, which are members of Ras GTPase superfamily. All Ras GTPase superfamily members bind to native ligands GTP and GDP, that switch on and off the proteins, respectively. Rab1 is physiologically essential for autophagy and transport between endoplasmic reticulum and Golgi apparatus. Pathologically, Rab1 is implicated in human cancers, a neurodegenerative disease, cardiomyopathy, and bacteria-caused infectious diseases. We have performed structural analyses on Rab1 protein using a unique ensemble of clustering methods, including multi-step principal component analysis, non-negative matrix factorization, and independent component analysis, to better identify representative Rab1 proteins than the application of a single clustering method alone does. We then used the identified representative Rab1 structures, resolved in multiple ligand states, to map their known and novel binding sites. We report here at least a novel binding site on Rab1, involving Rab1-specific residues that could be further explored for the rational design and development of investigative probes and/or therapeutic small molecules against the Rab1 protein. Proteins 2017; 85:859-871. © 2016 Wiley Periodicals, Inc.

Interaction of p190A RhoGAP with eIF3A and Other Translation Preinitiation Factors Suggests a Role in Protein Biosynthesis

The negative regulator of Rho family GTPases, p190A RhoGAP, is one of six mammalian proteins harboring so-called FF motifs. To explore the function of these and other p190A segments, we identified interacting proteins by tandem mass spectrometry. Here we report that endogenous human p190A, but not its 50% identical p190B paralog, associates with all 13 eIF3 subunits and several other translational preinitiation factors. The interaction involves the first FF motif of p190A and the winged helix/PCI domain of eIF3A, is enhanced by serum stimulation and reduced by phosphatase treatment. The p190A/eIF3A interaction is unaffected by mutating phosphorylated p190A-Tyr308, but disrupted by a S296A mutation, targeting the only other known phosphorylated residue in the first FF domain. The p190A-eIF3 complex is distinct from eIF3 complexes containing S6K1 or mammalian target of rapamycin (mTOR), and appears to represent an incomplete preinitiation complex lacking several subunits. Based on these findings we propose that p190A may affect protein translation by controlling the assembly of functional preinitiation complexes. Whether such a role helps to explain why, unique among the large family of RhoGAPs, p190A exhibits a significantly increased mutation rate in cancer remains to be determined.

Splicing-related single nucleotide polymorphism of RAB, member of RAS oncogene family like 2B (RABL2B) jeopardises semen quality in Chinese Holstein bulls.

RAB, member of RAS oncogene family like 2B (RABL2B) is a member of a poorly characterised clade of the RAS GTPase superfamily, which plays an essential role in male fertility, sperm intraflagellar transport and tail assembly. In the present study, we identified a novel RABL2B splice variant in bovine testis and spermatozoa. This splice variant, designated RABL2B-TV, is characterised by exon 2 skipping. Moreover, a single nucleotide polymorphism (SNP), namely c.125G>A, was found within the exonic splicing enhancer (ESE) motif, indicating that the SNP caused the production of the RABL2B-TV aberrant splice variant. This was demonstrated by constructing a pSPL3 exon capturing vector with different genotypes and transfecting these vectors into murine Leydig tumour cell line (MLTC-1) cells. Expression of the RABL2B-TV transcript was lower in semen from high- versus low-performance bulls. Association analysis showed that sperm deformity rate was significantly lower in Chinese Holstein bulls with the GG or GA genotype than in bulls with the AA genotype (P<0.05). In addition, initial sperm motility was significantly higher in individuals with the GG or GA genotype than in individuals with the AA genotype (P<0.05). The findings of the present study suggest that the difference in semen quality in bulls with different RABL2B genotypes is generated via an alternative splicing mechanism caused by a functional SNP within the ESE motif.

Direct Targeting of the Ras GTPase Superfamily Through Structure- Based Design.

The Ras superfamily of small monomeric GTPases includes some of the most prominent cancer targets for which no selective therapeutic agent has yet been successfully developed. The turn of the millennium saw a resurgence of efforts to target these enzymes using new and improved biophysical techniques to overcome the perceived difficulties of insurmountably high affinity for guanosine nucleotides and flat, flexible topology lacking suitable pockets for small molecule inhibitors. Further, recent investigations have begun to probe the dynamic conformational status of GTP-bound Ras, opening up new mechanisms of inhibition. While much of the literature has focused on the oncogenic Ras proteins, particularly K-Ras, these represent only a small minority of therapeutically interesting targets within the superfamily; for example, the Rab GTPases are the largest subfamily of about 70 members, and present an as yet untapped class of potential targets. The present review documents the key methodologies employed to date in structure-guided attempts to drug the Ras GTPases, and forecasts their transferability to other similarly challenging proteins in the superfamily.

Exploring the interactions of the RAS family in the human protein network and their potential implications in RAS-directed therapies.

RAS proteins are the founding members of the RAS superfamily of GTPases. They are involved in key signaling pathways regulating essential cellular functions such as cell growth and differentiation. As a result, their deregulation by inactivating mutations often results in aberrant cell proliferation and cancer. With the exception of the relatively well-known KRAS, HRAS and NRAS proteins, little is known about how the interactions of the other RAS human paralogs affect cancer evolution and response to treatment. In this study we performed a comprehensive analysis of the relationship between the phylogeny of RAS proteins and their location in the protein interaction network. This analysis was integrated with the structural analysis of conserved positions in available 3D structures of RAS complexes. Our results show that many RAS proteins with divergent sequences are found close together in the human interactome. We found specific conserved amino acid positions in this group that map to the binding sites of RAS with many of their signaling effectors, suggesting that these pairs could share interacting partners. These results underscore the potential relevance of cross-talking in the RAS signaling network, which should be taken into account when considering the inhibitory activity of drugs targeting specific RAS oncoproteins. This study broadens our understanding of the human RAS signaling network and stresses the importance of considering its potential cross-talk in future therapies.

MicroRNA-382-5p aggravates breast cancer progression by regulating the RERG/Ras/ERK signaling axis.

Aberrant activation of the Ras/ERK pathway mediates breast cancer initiation and aggressiveness. Therefore, it is important to identify miRNAs that modulate the Ras/ERK pathway during breast carcinogenesis and progression. The Ras GTPase superfamily member RERG (Ras-related and estrogen-regulated growth inhibitor) acts as a tumor suppressor to reduce breast cancer cell proliferation and tumor formation and has been suggested to have a regulatory role in the Ras/ERK pathway. In this study, we found that RERG exerted its tumor suppressor role by attenuating the activation of Ras/ERK signaling effectors. Furthermore, we found that miR-382-5p directly targets and represses RERG to attenuate the inhibitory effects of RERG on the oncogenic Ras/ERK pathway. Thereby, miR-382-5p promoted breast cancer cell viability, clonogenicity, survival, migration, invasion and in vivo tumorigenesis/metastasis. In clinical interpretation, miR-382-5p expression was negatively correlated with RERG expression, and it also significantly functioned as an independent oncomiR for the higher incidence and poorer prognosis of breast cancer. This novel connection highlights new diagnostic and prognostic roles for miR-382-5p and RERG in breast cancer.

Rho Kinase Inhibitors and Novel Ocular Drug Delivery Systems- A Revolutionary Step Towards the Treatment of Glaucoma

Glaucoma is an ocular disorder characterized by optic nerve damage which ultimately causes a progressive and an irreversible loss of vision, often characterized by an elevated intraocular pressure. Lowering the intraocular pressure (IOP) is the mainstay for glaucoma treatment but the neuroprotective agents would represent a promising class as the next-generation therapy. Protein kinases are involved considerably in signal transduction pathways confirmed by various mechanisms giving the evidence of Rho-kinase to be a versatile therapeutic target. Rho associated protein kinases also known as ROCK are serine/threonine kinases, belonging to the Ras superfamily of GTPases. The activation of Rho Kinase results in various actin-myosin arbitrated processes where contraction of actomyosin in the resident trabecular meshwork (TM) cells and extracellular matrix is responsible for the outflow of aqueous humour. Another major drawback of the currently available antiglaucoma drugs is their topical use which poses a problem for patient compliance. The patient intolerability and adherence to the existing therapy therefore call for newer drug delivery systems that would increase the clinical efficacy of the drugs. The neuroprotective agents are not considered suitable to be administered through the traditional topical or oral route. This complementary drug therapy requires a delivery system that could release the drug to the optic nerve in a sustained manner and also increase patient compliance and tolerability. This review summarizes the use of ROCK inhibitors that could prevent the damage to the optic nerve along with the reduction in IOP and novel drug delivery systems to increase the efficacy of the drugs.

Abstract 3656: Cooperation of Rab25 loss with oncogenes in breast cancer

Abstract Breast cancer is the most common type of cancer in females worldwide. A number of genes such as BRCA1, BRCA-2, Hras, and p53 undergo mutations and contribute to tumorigenesis of the mammary tissue. The RAB guanosine triphosphates (RAS-related in brain) belong to the Ras superfamily of GTPases. The human RAS family consists of 3 proto oncogenes - H-ras, K-ras, N-ras. Rab 25 belongs to the Rab11 subfamily and plays an important role in vesicular trafficking. The Rab proteins are ubiquitously expressed. Loss of Rab 25 expression has been reported in a number of breast cancer cases and in transformed mammary cell lines containing H-ras point mutations. Human Mammary Epithelial Cells (HMEC) were obtained from healthy individuals undergoing reduction mammoplasty. The cells were immortalized by transducing with LXSN CDK4 R24C. This was followed by transduction with hTERT, catalytic subunit of the telomerase enzyme. In this study, we are trying to understand if loss of Rab25 expression in HMEC co-operates with wild and mutant H-ras as well as other oncogenes and contributes to tumorigenesis. HMEC lines in which Rab25 has been knocked down were transduced with various oncogenes, including wild type and mutant H-ras, Her-2, and IGFR1. We examined the co-operativity between loss of Rab25 and these oncogenes in migration, anchorage independent growth, stem cell marker expression, and also in vivo tumorigenesis and metastasis in nude mice. Citation Format: Krishna A. Rao, Pooja S. Joshi. Cooperation of Rab25 loss with oncogenes in breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3656.

Three members of Ras GTPase superfamily are response to white spot syndrome virus challenge in Marsupenaeus japonicus.

Members of the Ras-like GTPase superfamily are key regulators of diverse cellular and developmental events, including differentiation, cell division, vesicle transport, nuclear assembly, and cytoskeleton control. In this study, three Ras family members (MjRap, MjRas, and MjRal) were cloned from Marsupenaeus japonicus. The full lengths of MjRap, MjRas, and MjRal are 788, 1330, and 2074bp, which encode the proteins of 186, 202, and 198 amino acids respectively. Phylogenetic analysis showed that Rap, Ras, and Ral from different species gather together. The MjRap, MjRas, and MjRal genes were ubiquitously expressed in the hemocytes, hepatopancreas, gills, stomach, and muscle. Results from the quantitative real-time polymerase chain reaction (qRT-PCR) showed that MjRal in the gills was upregulated 48 and 72h post-White spot syndrome virus (WSSV) challenge. No change in the MjRap or MjRas transcript was observed in the gills under the WSSV challenge. The RNAi of MjRal could enhance the WSSV replication. Injection of rMjRal protein could inhibit WSSV replication, but had no effect on VP28 expression. So, it could be concluded that MjRal was involved in shrimp anti-viral innate immune defense by inhibiting the WSSV replication.

095 Small non-coding snoRNAs control Ras superfamily GTPases in stem cell differentiation and cancer

095 Small non-coding snoRNAs control Ras superfamily GTPases in stem cell differentiation and cancer