Profiling and Targeting N-linked Glycosylation in High-Risk Neuroblastomas
Eric J. Rellinger, MD

Basic Science Project Mentors:  Christine Brainson, PhD, Andrew Lane, PhD, and Mark Evers, MD 
Clinical Project Mentor: John D’Orazio, MD, PhD 
External Mentor: K. Sreekumaran Nair, MD, PhD

Neuroblastoma (NB) is the most common extracranial solid tumor in children. MYCN-amplification is present in ~30% of NBs and sufficient for stratifying NBs as high-risk. N-MYC is a proto-oncogene that drives cancer cell growth, angiogenesis, and metabolism. Aberrant glutamine metabolism is a hallmark of MYC-driven cancers. N-MYC enhances expression of the glutamine transporter, ASCT2. ASCT2 has been shown to be critical for MYCN-amplified NB cell survival in vitro and in subcutaneous xenograft formation in vivo.  Our central hypothesis is that aberrant glutamine uptake via ASCT2 is critical for MYCN-amplified NB primary tumor growth and metastasis. We will test a new small molecule inhibitor of ASCT2 (V-9032) in advanced patient-derived orthotopic xenograft models of MYCN-amplified NB. Stable-isotope resolved metabolomics will be used to define aberrant metabolic activated to sustain NB survival in the presence of ASCT2 blockade. We will also seek to define metabolic vulnerabilities uncovered by ASCT2 inhibition utilizing a high-throughput siRNA screen for synthetic lethality in MYCN-amplified NB cell lines.    

TRIM28 fuels prostate cancer growth through SETDB1-mediated epigenetic silencing of androgen metabolic genes UGT2B15 and UGT2B17
Ka-wing Fong, PhD
 

Basic Science Project Mentors: Richard Higashi, PhD, and Xiaoqi Liu, PhD
Clinical Project Mentor: Peng Wang, MD 
External Project Mentor: Douglas R. Spitz, PhD 

Prostate cancer (PCa) is the second-leading cause of cancer-related death in men. The mainstay treatment for metastatic PCa is androgen deprivation therapy (ADT). However, the disease will inevitably return in an incurable form termed castration-resistant prostate cancer (CRPC). Importantly, aberrant androgen receptor (AR) activation in the milieu of low androgen is the main driver of CRPC. Molecular characterization of CRPC paves the way for discovery of novel therapeutic targets, and my previous studies showed that TRIM28 is aberrantly upregulated in advanced PCa. High TRIM28 levels are associated with worse clinical outcomes, which suggests that TRIM28 could serve as a promising target for PCa therapy. It is known that TRIM28 in a complex with trimethyl-histone H3 lysine 9 (H3K9me3)-specific methyltransferase (SETDB1) possesses transcriptional co-repressor activity but its genomic targets remain largely unexplored in PCa. Moreover, the TRIM28 downstream oncogenic pathway has not been comprehensively investigated in PCa. By molecular gene signature analysis, I found that the steroid hormone metabolic pathway is regulated by TRIM28. In particular, I found that the androgen eliminating enzymes UGT2B15 and UGT2B17 are the key TRIM28-repressed genes. It is known that genomic targeting of the TRIM28 complex is facilitated by transcription factors that bind to specific DNA recognition motifs. My data revealed that TRIM28 interacts with AR. In addition, my preliminary results indicated there is co-occupancy of TRIM28, AR and H3K9me3 deposition at UGT2B15 and UGT2B17 gene loci. Based on these findings, I hypothesize that TRIM28 acts together with AR to epigenetically silence the expression of androgen metabolic enzymes through SETDB1-mediated H3K9me3. I propose to test this hypothesis in Aim1. UGT2B15 and UGT2B17 are known to inactivate androgen through glucuronidation using UDP-GlucA as the sugar-donor. Given that the overexpression of UGT2B15 and UGT2B17 correlate to more UDP-GlucA consumption, I hypothesize that levels of UDP-GlucA will decrease in TRIM28 knockdown cells or with treatment of the SETDB1 inhibitor, Mit, in CRPC cells. I propose to test this hypothesis in Aim2. The results from this proposal will not only reveal a novel epigenetic mechanism for regulating androgen glucuronidation, but also have significant implications for the development of SETDB1-targeted therapy for CRPC treatment.
 

An intra-vital metabolic microscope to reveal the mechanisms of radiation resistance in head and neck carcinomas
Caigang Zhu, PhD

Basic Science Project Mentors: Teresa Fan, PhD and Ren Xu, PhD
Clinical Project Mentor: Susanne M. Arnold MD, FACP
External Project Mentor: Martin Hauer-Jensen, MD, PhD, FACS 
 

Radio-resistance (RR) leads to poor prognosis in head and neck squamous cell cancer (HNSCC) patients. The failure of radiotherapy (RT) has been attributed to hypoxia. However, new studies found that RT-induced re-oxygenation rates alone cannot distinguish primary from recurring HNSCC tumors, as some recurrent tumors also showed re-oxygenation after RT. Hypoxia-Inducible Factor-1 (HIF-1) is known to regulate many growth factors to promote aerobic glycolysis and angiogenesis. We hypothesize that RT-induced HIF-1 expression and subsequent alterations in metabolism/vasculature underlie HNSCC RR. Unraveling metabolic traits of cells that evade RT and recur, and the role of the supporting vasculature, is critical to developing strategies to prevent HNSCC recurrence and improve patient survival. However, there are surprisingly few techniques available to provide a systems-level view of these hallmarks together in vivo. To fill these gaps, I will build a portable multi-parametric microscope to measure the major axes of metabolism and vasculature in small animal models in vivo. I will then use these platforms to study the effect of radiation on HNSCC tumors and test our hypothesis on HNSCC RR development. This technology fills an important gap between in vitro studies on cells and whole body imaging, and is complementary to metabolomics and immunohistochemistry (IHC). I envision that this system will be well suited to study tumor RR and recurrence in patient-derived xenograft (PDX) and organoid models, which can faithfully recapitulate many micro-environmental features of patient tumors.