Justina Dolorita McEvoy
- Assistant Professor, Molecular and Cellular Biology
- Assistant Professor, BIO5 Institute
- Assistant Professor, Pediatrics
- Assistant Professor, Cancer Biology - GIDP
- Ph.D. Biology
- Brown University, Providence, Rhode Island, USA
- In vivo requirement of the Cul3 ubiquitin ligase in cyclin E degradation and maintenance of the cell cycle
- B.S. Biology
- California State Polytechnic University, Pomona, California, USA
- Assistant Professor, University of Arizona, Tucson, Arizona (2014 - Ongoing)
- Postdoctoral Fellow, St. Jude Children’s Research Hospital (2007 - 2014)
- Keystone Symposia Early Career Investigator Travel Award
- Keystone Symposia, Spring 2015
My lab is interested in understanding how the deregulation of developmental pathways can contribute to tumorigenesis in pediatric cancer. Currently, there are two major projects in my laboratory. The first project focuses on the regulation of differentiation pathways in a rare pediatric cancer of the retina called retinoblastoma. I recently discovered that individual retinoblastoma cells have a hybrid molecular signature with features of retinal progenitor cells and multiple differentiated lineages. I then went on to show that these differentiation programs were deregulated through epigenetic mechanisms as a result of inactivation of the RB1 tumor suppressor gene. My current working hypothesis is that Rb may play an important role in silencing the retinal progenitor program when cells exit the cell cycle and commit to particular neuronal fates. To test this hypothesis, we are performing single cell gene expression array analysis on different classes of Rb-deficient neurons in the mouse retina. Preliminary data reveal retinal progenitor genes are aberrantly expressed in differentiated neurons and further refinement of this analysis identified a subset of these genes as putative Rb targets. Data from this project will provide important insight into Rb-dependent regulation of retinal developmental programs. In addition, we will gain further understanding into why retinoblastomas coexpress multiple programs when RB1 is inactivated in the developing retina.To extend my discoveries in retinoblastoma to other pediatric solid tumors, I have launched a second project focused on a childhood cancer with features of developing muscle called rhabdomyosarcoma. A subset of rhabdomyosarcomas (alveolar rhabdomyosarcoma) have no recurrent somatic mutations in any know cancer pathways. This led me to hypothesize that epigenetic processes may be driving tumorigenesis in this devastating childhood cancer. Indeed, there are now several examples that have emerged where mutations are identified in epigenetic regulators in developmental tumors such as rhabdoid tumors, neuroblastomas, medulloblastoma, ependynomas and gliomas. To test this hypothesis, we will perform integrated analyses using RNAseq, DNA methylation, and ChIP-seq for histone modifications in orthotopic xenografts derived from primary patient tumors. Preliminary integrated analysis of RNAseq and DNA methylation reveal differences in the methylation state of genes involved in muscle differentiation and cancer initiation including the WNT signaling pathway. Taken together, we hope to shed light on fundamental mechanisms of normal development and tumorigenesis and provide novel therapeutic approaches for rhabdomyosarcomas and retinoblastoma.
My interests as a teacher is to show students how to think critically about a problem and then arrive at an efficient solution using available resources. These skills are necessary for success in science or any other field. I am passionate about teaching students how to identify an important question, develop a hypothesis, design the appropriate experiment, and, most importantly, never be afraid of unexpected results, as these can lead to great discoveries.In the classroom, I will develop curricula that introduce key biological concepts. To make the science more relatable, I will incorporate how these biological concepts impact our daily lives (i.e. by discussing news articles on human diseases, genetic testing, etc.). To give students a clear understanding of how independent researchers approach scientific questions, I plan to use an approach I found effective for a graduate class I led at Rhodes College in Memphis, TN. After introducing a current research question to the students, I encouraged them to critique major papers on the topic, dissect the researchers’ experiments, offer alternative interpretations of the data, and conceptualize and troubleshoot new experiments to test their ideas. The students responded well to this approach because they felt personally invested in our discussions.As a mentor, I will pass on to my postdoctoral fellows and students the fundamental research principles taught to me by my excellent mentors. I have learned many important lessons, but four stand out as being integral to success as an independent investigator. First is developing an interesting question that is feasible and will have an impact in the field. Second is thoughtfully designing multiple experimental approaches to test the question. Third is critically interpreting the data, treating unexpected results as a chance to learn something new, not as a failure. Fourth is contributing to a dialogue: scientific discussions—whether at a meeting, during a presentation, or in the hallway—help researchers foster ideas, design better experiments, and develop meaningful collaborations. Students and postdoctoral fellows who train in my lab will learn these lessons, as well meet with me individually to discuss career development and current projects. I also plan to hold group meetings that incorporate “chalk talk” style discussions about current projects and key mentoring topics, such as grant writing, lab management, publication writing, etc. For fall 2017, I am highly motivated to teach the Cancer Biology MCB325. As an undergraduate and graduate student, learning about Cancer Biology was one of my favorite subjects. I always found it fascinating that even though there is decades of cancer-related research by brilliant scientists, this disease still has not been eradicated from people we know and especially our loved ones.
Integrative Approaches to BioMCB 585 (Fall 2016)
ResearchCBIO 900 (Fall 2016)
Research ConferenceCBIO 695A (Fall 2016)
Senior CapstoneBIOC 498 (Fall 2016)
Special Tutoring WkshpMCB 497A (Fall 2016)
The Biology of CancerMCB 325 (Fall 2016)
Directed RsrchMCB 492 (Spring 2016)
Honors ThesisECOL 498H (Spring 2016)
Honors ThesisMCB 498H (Spring 2016)
ResearchCBIO 900 (Spring 2016)
Research ConferenceCBIO 695A (Spring 2016)
Honors ThesisECOL 498H (Fall 2015)
Honors ThesisMCB 498H (Fall 2015)
ResearchCBIO 900 (Fall 2015)
Research ConferenceCBIO 695A (Fall 2015)
The Biology of CancerMCB 302 (Fall 2015)
Honors Independent StudyECOL 499H (Spring 2015)
Independent StudyMCB 499 (Spring 2015)
Introduction to ResearchMCB 795A (Spring 2015)
- Kratochvill, F., Neale, G., Haverkamp, J. M., Van de Velde, L., Smith, A. M., Kawauchi, D., McEvoy, J., Roussel, M. F., Dyer, M. A., Qualls, J. E., & Murray, P. J. (2015). TNF Counterbalances the Emergence of M2 Tumor Macrophages. Cell reports, 12(11), 1902-14.More infoCancer can involve non-resolving, persistent inflammation where varying numbers of tumor-associated macrophages (TAMs) infiltrate and adopt different activation states between anti-tumor M1 and pro-tumor M2 phenotypes. Here, we resolve a cascade causing differential macrophage phenotypes in the tumor microenvironment. Reduction in TNF mRNA production or loss of type I TNF receptor signaling resulted in a striking pattern of enhanced M2 mRNA expression. M2 gene expression was driven in part by IL-13 from eosinophils co-recruited with inflammatory monocytes, a pathway that was suppressed by TNF. Our data define regulatory nodes within the tumor microenvironment that balance M1 and M2 populations. Our results show macrophage polarization in cancer is dynamic and dependent on the balance between TNF and IL-13, thus providing a strategy for manipulating TAMs.
- McEvoy, J., Nagahawatte, P., Finkelstein, D., Richards-Yutz, J., Valentine, M., Ma, J., Mullighan, C., Song, G., Chen, X., Wilson, M., Brennan, R., Pounds, S., Becksfort, J., Huether, R., Lu, C., Fulton, R. S., Fulton, L. L., Hong, X., Dooling, D. J., , Ochoa, K., et al. (2014). RB1 gene inactivation by chromothripsis in human retinoblastoma. Oncotarget, 5(2), 438-50.More infoRetinoblastoma is a rare childhood cancer of the developing retina. Most retinoblastomas initiate with biallelic inactivation of the RB1 gene through diverse mechanisms including point mutations, nucleotide insertions, deletions, loss of heterozygosity and promoter hypermethylation. Recently, a novel mechanism of retinoblastoma initiation was proposed. Gallie and colleagues discovered that a small proportion of retinoblastomas lack RB1 mutations and had MYCN amplification . In this study, we identified recurrent chromosomal, regional and focal genomic lesions in 94 primary retinoblastomas with their matched normal DNA using SNP 6.0 chips. We also analyzed the RB1 gene mutations and compared the mechanism of RB1 inactivation to the recurrent copy number variations in the retinoblastoma genome. In addition to the previously described focal amplification of MYCN and deletions in RB1 and BCOR, we also identified recurrent focal amplification of OTX2, a transcription factor required for retinal photoreceptor development. We identified 10 retinoblastomas in our cohort that lacked RB1 point mutations or indels. We performed whole genome sequencing on those 10 tumors and their corresponding germline DNA. In one of the tumors, the RB1 gene was unaltered, the MYCN gene was amplified and RB1 protein was expressed in the nuclei of the tumor cells. In addition, several tumors had complex patterns of structural variations and we identified 3 tumors with chromothripsis at the RB1 locus. This is the first report of chromothripsis as a mechanism for RB1 gene inactivation in cancer.
- Benavente, C. A., McEvoy, J. D., Finkelstein, D., Wei, L., Kang, G., Wang, Y., Neale, G., Ragsdale, S., Valentine, V., Bahrami, A., Temirov, J., Pounds, S., Zhang, J., & Dyer, M. A. (2013). Cross-species genomic and epigenomic landscape of retinoblastoma. Oncotarget, 4(6), 844-59.More infoGenetically engineered mouse models (GEMMs) of human cancer are important for advancing our understanding of tumor initiation and progression as well as for testing novel therapeutics. Retinoblastoma is a childhood cancer of the developing retina that initiates with biallelic inactivation of the RB1 gene. GEMMs faithfully recapitulate the histopathology, molecular, cellular, morphometric, neuroanatomical and neurochemical features of human retinoblastoma. In this study, we analyzed the genomic and epigenomic landscape of murine retinoblastoma and compared them to human retinoblastomas to gain insight into shared mechanisms of tumor progression across species. Similar to human retinoblastoma, mouse tumors have low rates of single nucleotide variations. However, mouse retinoblastomas have higher rates of aneuploidy and regional and focal copy number changes that vary depending on the genetic lesions that initiate tumorigenesis in the developing murine retina. Furthermore, the epigenetic landscape in mouse retinoblastoma was significantly different from human tumors and some pathways that are candidates for molecular targeted therapy for human retinoblastoma such as SYK or MCL1 are not deregulated in GEMMs. Taken together, these data suggest there are important differences between mouse and human retinoblastomas with respect to the mechanism of tumor progression and those differences can have significant implications for translational research to test the efficacy of novel therapies for this devastating childhood cancer.
- Chen, X., Stewart, E., Shelat, A. A., Qu, C., Bahrami, A., Hatley, M., Wu, G., Bradley, C., McEvoy, J., Pappo, A., Spunt, S., Valentine, M. B., Valentine, V., Krafcik, F., Lang, W. H., Wierdl, M., Tsurkan, L., Tolleman, V., Federico, S. M., , Morton, C., et al. (2013). Targeting oxidative stress in embryonal rhabdomyosarcoma. Cancer cell, 24(6), 710-24.More infoRhabdomyosarcoma is a soft-tissue sarcoma with molecular and cellular features of developing skeletal muscle. Rhabdomyosarcoma has two major histologic subtypes, embryonal and alveolar, each with distinct clinical, molecular, and genetic features. Genomic analysis shows that embryonal tumors have more structural and copy number variations than alveolar tumors. Mutations in the RAS/NF1 pathway are significantly associated with intermediate- and high-risk embryonal rhabdomyosarcomas (ERMS). In contrast, alveolar rhabdomyosarcomas (ARMS) have fewer genetic lesions overall and no known recurrently mutated cancer consensus genes. To identify therapeutics for ERMS, we developed and characterized orthotopic xenografts of tumors that were sequenced in our study. High-throughput screening of primary cultures derived from those xenografts identified oxidative stress as a pathway of therapeutic relevance for ERMS.
- McEvoy, J., Ulyanov, A., Brennan, R., Wu, G., Pounds, S., Zhang, J., & Dyer, M. A. (2012). Analysis of MDM2 and MDM4 single nucleotide polymorphisms, mRNA splicing and protein expression in retinoblastoma. PloS one, 7(8), e42739.More infoRetinoblastoma is a childhood cancer of the developing retina that begins in utero and is diagnosed in the first years of life. Biallelic RB1 gene inactivation is the initiating genetic lesion in retinoblastoma. The p53 gene is intact in human retinoblastoma but the pathway is believed to be suppressed by increased expression of MDM4 (MDMX) and MDM2. Here we quantify the expression of MDM4 and MDM2 mRNA and protein in human fetal retinae, primary retinoblastomas, retinoblastoma cell lines and several independent orthotopic retinoblastoma xenografts. We found that MDM4 is the major p53 antagonist expressed in retinoblastoma and in the developing human retina. We also discovered that MDM4 protein steady state levels are much higher in retinoblastoma than in human fetal retinae. This increase would not have been predicted based on the mRNA levels. We explored several possible post-transcriptional mechanisms that may contribute to the elevated levels of MDM4 protein. A proportion of MDM4 transcripts are alternatively spliced to produce protein products that are reported to be more stable and oncogenic. We also discovered that a microRNA predicted to target MDM4 (miR191) was downregulated in retinoblastoma relative to human fetal retinae and a subset of samples had somatic mutations that eliminated the miR-191 binding site in the MDM4 mRNA. Taken together, these data suggest that post-transcriptional mechanisms may contribute to stabilization of the MDM4 protein in retinoblastoma.
- Zhang, J., Benavente, C. A., McEvoy, J., Flores-Otero, J., Ding, L., Chen, X., Ulyanov, A., Wu, G., Wilson, M., Wang, J., Brennan, R., Rusch, M., Manning, A. L., Ma, J., Easton, J., Shurtleff, S., Mullighan, C., Pounds, S., Mukatira, S., , Gupta, P., et al. (2012). A novel retinoblastoma therapy from genomic and epigenetic analyses. Nature, 481(7381), 329-34.More infoRetinoblastoma is an aggressive childhood cancer of the developing retina that is initiated by the biallelic loss of RB1. Tumours progress very quickly following RB1 inactivation but the underlying mechanism is not known. Here we show that the retinoblastoma genome is stable, but that multiple cancer pathways can be epigenetically deregulated. To identify the mutations that cooperate with RB1 loss, we performed whole-genome sequencing of retinoblastomas. The overall mutational rate was very low; RB1 was the only known cancer gene mutated. We then evaluated the role of RB1 in genome stability and considered non-genetic mechanisms of cancer pathway deregulation. For example, the proto-oncogene SYK is upregulated in retinoblastoma and is required for tumour cell survival. Targeting SYK with a small-molecule inhibitor induced retinoblastoma tumour cell death in vitro and in vivo. Thus, retinoblastomas may develop quickly as a result of the epigenetic deregulation of key cancer pathways as a direct or indirect result of RB1 loss.
- McEvoy, J., Flores-Otero, J., Zhang, J., Nemeth, K., Brennan, R., Bradley, C., Krafcik, F., Rodriguez-Galindo, C., Wilson, M., Xiong, S., Lozano, G., Sage, J., Fu, L., Louhibi, L., Trimarchi, J., Pani, A., Smeyne, R., Johnson, D., & Dyer, M. A. (2011). Coexpression of normally incompatible developmental pathways in retinoblastoma genesis. Cancer cell, 20(2), 260-75.More infoIt is widely believed that the molecular and cellular features of a tumor reflect its cell of origin and can thus provide clues about treatment targets. The retinoblastoma cell of origin has been debated for over a century. Here, we report that human and mouse retinoblastomas have molecular, cellular, and neurochemical features of multiple cell classes, principally amacrine/horizontal interneurons, retinal progenitor cells, and photoreceptors. Importantly, single-cell gene expression array analysis showed that these multiple cell type-specific developmental programs are coexpressed in individual retinoblastoma cells, which creates a progenitor/neuronal hybrid cell. Furthermore, neurotransmitter receptors, transporters, and biosynthetic enzymes are expressed in human retinoblastoma, and targeted disruption of these pathways reduces retinoblastoma growth in vivo and in vitro.
- Laurie, N., Mohan, A., McEvoy, J., Reed, D., Zhang, J., Schweers, B., Ajioka, I., Valentine, V., Johnson, D., Ellison, D., & Dyer, M. A. (2009). Changes in retinoblastoma cell adhesion associated with optic nerve invasion. Molecular and cellular biology, 29(23), 6268-82.More infoIn the 1970s, several human retinoblastoma cell lines were developed from cultures of primary tumors. As the human retinoblastoma cell lines were established in culture, growth properties and changes in cell adhesion were described. Those changes correlated with the ability of the human retinoblastoma cell lines to invade the optic nerve and metastasize in orthotopic xenograft studies. However, the mechanisms that underlie these changes were not determined. We used the recently developed knockout mouse models of retinoblastoma to begin to characterize the molecular, cellular, and genetic changes associated with retinoblastoma tumor progression and optic nerve invasion. Here we report the isolation and characterization of the first mouse retinoblastoma cell lines with targeted deletions of the Rb family. Our detailed analysis of these cells as they were propagated in culture from the primary tumor shows that changes in cadherin-mediated cell adhesion are associated with retinoblastoma invasion of the optic nerve prior to metastasis. In addition, the same changes in cadherin-mediated cell adhesion correlate with the invasive properties of the human retinoblastoma cell lines isolated decades ago, providing a molecular mechanism for these earlier observations. Most importantly, our studies are in agreement with genetic studies on human retinoblastomas, suggesting that changes in this pathway are involved in tumor progression.
- McEvoy, J. D., Kossatz, U., Malek, N., & Singer, J. D. (2007). Constitutive turnover of cyclin E by Cul3 maintains quiescence. Molecular and cellular biology, 27(10), 3651-66.More infoTwo distinct pathways for the degradation of mammalian cyclin E have previously been described. One pathway is induced by cyclin E phosphorylation and is dependent on the Cul1/Fbw7-based E3 ligase. The other pathway is dependent on the Cul3-based E3 ligase, but the mechanistic details of this pathway have yet to be elucidated. To establish the role of Cul3 in the degradation of cyclin E in vivo, we created a conditional knockout of the Cul3 gene in mice. Interestingly, the biallelic loss of Cul3 in primary fibroblasts derived from these mice results in increased cyclin E expression and reduced cell viability, paralleling the loss of Cul3 protein expression. Cell cycle analysis of viable, Cul3 hypomorphic cells shows that decreasing the levels of Cul3 increases both cyclin E protein levels and the number of cells in S phase. In order to examine the role of Cul3 in an in vivo setting, we determined the effect of deletion of the Cul3 gene in liver. This gene deletion resulted in a dramatic increase in cyclin E levels as well as an increase in cell size and ploidy. The results we report here show that the constitutive degradation pathway for cyclin E that is regulated by the Cul3-based E3 ligase is essential to maintain quiescence in mammalian cells.
- Watai, Y., Kobayashi, A., Nagase, H., Mizukami, M., McEvoy, J., Singer, J. D., Itoh, K., & Yamamoto, M. (2007). Subcellular localization and cytoplasmic complex status of endogenous Keap1. Genes to cells : devoted to molecular & cellular mechanisms, 12(10), 1163-78.More infoKeap1 acts as a sensor for oxidative/electrophilic stress, an adaptor for Cullin-3-based ubiquitin ligase, and a regulator of Nrf2 activity through the interaction with Nrf2 Neh2 domain. However, the mechanism(s) of Nrf2 migration into the nucleus in response to stress remains largely unknown due to the lack of a reliable antibody for the detection of endogenous Keap1 molecule. Here, we report the generation of a new monoclonal antibody for the detection of endogenous Keap1 molecules. Immunocytochemical analysis of mouse embryonic fibroblasts with the antibody revealed that under normal, unstressed condition, Keap1 is localized primarily in the cytoplasm with minimal amount in the nucleus and endoplasmic reticulum. This subcellular localization profile of Keap1 appears unchanged after treatment of cells with diethyl maleate, an electrophile, and/or Leptomycin B, a nuclear export inhibitor. Subcellular fractionation analysis of mouse liver cells showed similar results. No substantial change in the subcellular distribution profile could be observed in cells isolated from butylated hydroxyanisole-treated mice. Analyses of sucrose density gradient centrifugation of mouse liver cells indicated that Keap1 appears to form multiprotein complexes in the cytoplasm. These results demonstrate that endogenous Keap1 remains mostly in the cytoplasm, and electrophiles promote nuclear accumulation of Nrf2 without altering the subcellular localization of Keap1.
- Salinas, G. D., Blair, L. A., Needleman, L. A., Gonzales, J. D., Chen, Y., Li, M., Singer, J. D., & Marshall, J. (2006). Actinfilin is a Cul3 substrate adaptor, linking GluR6 kainate receptor subunits to the ubiquitin-proteasome pathway. The Journal of biological chemistry, 281(52), 40164-73.More infoKainate receptors have been implicated in excitotoxic neuronal death induced by diseases such as epilepsy and stroke. Actinfilin, a synaptic member of the BTB-Kelch protein family, is known to bind to the actin cytoskeleton. However, little is understood about its function at the synapse. Here, we report that actinfilin is able to bind to GluR6, a kainate-type glutamate receptor subunit, and target GluR6 for degradation. Like many members of its protein family, actinfilin acts as a substrate adaptor, binding Cullin 3 (Cul3) and linking GluR6 to the E3 ubiquitin-ligase complex. We map this interaction to the Kelch repeat domain of actinfilin and the GluR6 C terminus. Co-immunoprecipitation and immunofluorescence studies show that GluR6 is ubiquitinated, and that GluR6 levels are decreased by actinfilin overexpression but increased when actinfilin levels are reduced by specific RNA interference. Furthermore, actinfilin-Cul3 interactions appear to be important for regulating surface GluR6 expression. Synaptic GluR6 levels are elevated in mice with lowered neuronal Cul3 expression and when dominant-negative forms of Cul3 are transfected into hippocampal neurons. Together our data demonstrate that actinfilin acts as a scaffold, linking GluR6 to the Cul3 ubiquitin ligase to provide a novel mechanism for kainate receptor degradation.
- McEvoy, J. D. (2016, December). Epigenetic Deregulation of Novel lncRNAs in Rhabdomyosarcoma. Basic Medical Sciences Seminar Series. 600 E. Van Buren Street, Phoenix, AZ: University of Arizona.
- McEvoy, J. D. (2014, October). Genetic and Epigenetic Contributions in Retinoblastoma. 2014 Joint Biology Research Retreat. Oracle, AZ.
- McEvoy, J. D. (2014, October). Genetic and Epigenetic Contributions in Retinoblastoma. Cancer Biology Research Conference. University of Arizona Cancer Center: Nathan Ellis - organizer.
- McEvoy, J. D., & McEvoy, J. D. (2016, September). Bridging Epigenetic and Development to Reveal Novel Therapeutic Targets in Pediatric Cancers. Genetics and Genomics Grand Rounds. Tucson, AZ: University of Arizona, College of Medicine.
- McEvoy, J. D., Tiet, N., & Yang, H. (2016, April). Epigenetic Deregulation of HOX Genes in Rhabdoymyosarcoma. Honors Engagement Expo. University of Arizona: University of Arizona.More infoStudent poster presentation - Nancy Tiet
- McEvoy, J. D., Yang, H., & Tiet, N. (2016, April). Epigenetic Deregulation of HOX Genes in Rhabdoymyosarcoma. EEB Undergraduate Poster SessionUniversity of Arizona.More infoNancy Tiet presented a poster
- McEvoy, J. D., Yang, H., & Tiet, N. (2016, February). Epigenetic Deregulation of HOX Genes in Rhabdoymyosarcoma. Biological, Engineering, and Chemical Undergraduate Research (BECUR) ConferenceUniversity of Arizona.More infoNancy Tiet presented a poster of her research. WINNER for outstanding presentation
- McEvoy, J. D. (2014, October). Genetic and Epigenetic Contributions in Retinoblastoma. Cancer Biology Retreat. Tucson Botanical Gardens: Cancer Biology Program UA Cancer Center.
- McEvoy, J. D., Xu, C., Chen, X., Stewart, E., & Dyer, M. (2015, January 25-30). Genetic and Epigenetic Contributions in Rhabdomyosarcomas. Keystone Symposia/Epigenetics and Cancer. Keystone Colorado.
- McEvoy, J. D., Yang, H., & Tiet, N. (2015, October). Epigenetic Deregulation of HOX Genes in Rhabdoymyosarcoma. Vision to your Future Poster PresentationUniversity of Arizona.More infoNancy Tiet presented a poster of her research
- McEvoy, J. D., & Dyer, M. (2014. Genetic and Epigenetic Discoveries in Retinoblastoma.More infoA review of the most recent epigenetic and genomic discoveries in retinoblastoma.