Abnormal interactions between our immune system and our gut microbes can lead to inflammation that drives colon and gastric cancer growth. Dr. Brian [HHMI Fellow] is investigating how the immune system recognizes and responds to these microbes, and how these interactions contribute to abnormal inflammation that can fuel cancer growth. Microbiota-immune interactions have been generally studied in the context of "clean" laboratory mice, but these models do not fully capture human immunology and the complex interplay between host cells and foreign microbes. To overcome this, Dr. Brian plans to study these interactions in "dirty" mice, colonized by a diverse community of microbes as well as pathogens. He will then use laboratory mice with more defined microbial communities to test how recognition of specific microbes by the immune system is regulated and how disruptions to this regulation contributes to inflammation. Dr. Brian received his PhD from the University of Minnesota, Twin Cities and his BS from the University of California, Santa Barbara.

Dietary interventions such as caloric restriction (CR) and ketogenic diet (KD) are reported to limit tumor growth partially by modulating stem cell function. The intestine functions as the main organ of nutrient absorption and, due to rapid tissue renewal via intestinal stem cells (ISCs), is sensitive to shifts in the body’s metabolic state before and after eating. Both CR and KD conditions dramatically enhance the activity of an enzyme in ISCs known as HMGCS2. This enzyme controls ketogenesis, the conversion of fatty acids into ketone bodies as a means of producing energy when glucose is unavailable. Dr. Chi aims to dissect the role of ketone body metabolites in modulating intestinal stem cell function and tumor growth. With a better understanding of how intestinal stem cells adapt to diverse diets, he hopes to identify new strategies or dietary interventions that prevent and reduce the growth of cancers in the intestinal tract. Dr. Chi received his PhD from the University of California, Los Angeles and his BS from Zhejiang University.

Dr. Cote is exploring embryonic development to better understand how cells cooperate and build complex tissues. Since cancer cells often erroneously redeploy developmental programs and behaviors, her research into how neighboring cells align will yield insights into how cancerous cells metastasize and invade other tissues. Dr. Cote is combining tissue-specific genetic manipulations and laser cell ablations with live imaging during Caenorhabditis elegans digestive tract development to reveal how intracellular organization in one cell type can influence the alignment, polarity, and function of cells in the neighboring tissues.

In many cancer types, microbiota have emerged as an influential component of the tumor environment. Dr. Dohlman [Meghan E. Raveis Fellow] studies Fusobacterium nucleatum, a bacterial species that colonizes around half of colorectal tumors. The reasons for F. nucleatum’s preferential colonization of these tissues are poorly understood, and investigating this phenomenon could lead to improvements in cancer diagnosis and treatment. To this end, Dr. Dohlman is using computational methods to study strains of cancer-associated F. nucleatum, searching for genomic features that promote colonization of colorectal cancers. In parallel, he is analyzing the genomes of colorectal tumors to identify genetic changes that in turn promote F. nucleatum colonization. Dr. Dohlman received his PhD from Duke University, Durham and his BA from Wesleyan University, Middletown.

Regulation of gene transcription is a major mechanism cells use to modify the levels of certain proteins in response to their environment. A specific class of genes called immediate-early genes (IEGs) responds rapidly to external stimuli to adjust downstream gene transcription programs before any new proteins are synthesized. Abnormal expression of IEGs has been implicated in multiple types of cancers, as well as in neurological syndromes like addiction. Despite extensive study, the regulation of IEGs remains poorly understood. Dr. Gu’s work focuses on revealing the molecular mechanisms of IEG expression in cells and establishing model systems to study the physiological and disease-related outcomes caused by misregulation of this process. Dr. Gu [National Mah Jongg League Fellow] received her PhD from MIT and her BSc from Peking University.

DNA stores the information for making all the proteins in an organism. Transfer RNA (tRNA) plays a key role in building the proteins from this blueprint. tRNA molecules recognize specific sequences (three-letter codons) and deliver the corresponding amino acids needed to make a protein. Dr. Hsu recently found that certain starvation conditions can cause some tRNAs to be modulated in colorectal cancer cells. He will study the changes in tRNA levels that occur in response to cellular starvation states. He aims to shed light on how cancer cells adapt to starvation, which potentially can lead to new therapeutic approaches to target metabolic dependencies in cancer.

Immune cells called macrophages can swallow bacteria and contain them in membrane-bound compartments called phagosomes. From inside the phagosome, some bacteria stimulate immune pathways in the cytosol, but it is unclear how immune signals are transmitted across the membrane from the phagosome into the cytosol. To investigate, Dr. Jastrab [Robert Black Fellow] has developed a macrophage infection model using mutants of the bacterium Staphylococcus aureus that stimulate an immune complex in the cytosol called the inflammasome. He aims to identify the host and microbial pathways that facilitate activation of the inflammasome during infection. Because the activation of cytosolic immune receptors by phagosomal bacteria may be important in protection against colorectal cancer, Dr. Jastrab’s work aims to elucidate pathways that may be manipulated to prevent tumorigenesis and enhance anti-tumor immunity. Dr. Jastrab received his MD, PhD from New York University School of Medicine, New York and his BS from Tufts University, Medford.

Mitochondria harbor independent genetic material known as mitochondrial DNA (mtDNA). This compact, circular molecule encodes proteins essential for the assembly of the mitochondrial electron transport chain to generate energy in form of ATP. Like nuclear DNA, mtDNA is susceptible to damage and mutations. One of the most common disease-causing aberrations of mtDNA is termed “common deletion.” This aberration disrupts mitochondrial function, resulting in neuromuscular diseases and potentially certain cancers, including colorectal cancer. Due to a lack of tools to modify the mitochondrial genome, researchers currently do not understand the mechanisms behind common deletion. Dr. Kavlashvili [Timmerman Traverse Fellow] aims to investigate by using cutting-edge molecular biology tools to edit and visualize mtDNA genomes. She will then be poised to unravel impacts of this deletion on various tissues, in order to ultimately mitigate its pathological impact. Dr. Kavlashvili received her PhD from Vanderbilt University, Nashville and her BS from University of Iowa, Iowa City.

In addition to acute illness, viruses can cause cancers. While our understanding of cellular immunity against viruses that have DNA-based genomes is robust, we know less about how cells protect themselves against RNA-based viruses such as hepatitis C, a leading cause of liver cancer. Because many cellular defenses against viruses are known to be shared between mammals and bacteria, Dr. Mendoza [HHMI Fellow] is looking for new cellular defenses against RNA viruses in bacteria and will investigate how these defenses work. The resulting discovery of anti-viral defenses will broaden our understanding of how cells protect themselves against RNA viruses, which will improve our capacity to support patients' immune systems when infected with cancer-causing RNA viruses. Dr. Mendoza received their PhD from the University of California, San Francisco, and their BS from the University of Miami.

Human cells compact their vast genomes into the small confines of the nucleus by wrapping their DNA into a highly complex structure called chromatin. Packaging DNA into chromatin, however, affects all nucleic acid-transacting machines (e.g., transcription factors) that need to access the genomic information stored in the DNA. NuRD is a large multi-subunit protein complex that plays a major role in making chromatin either accessible or inaccessible. Dysregulation of NuRD and aberrant targeting of the complex can result in the emergence of several types of cancers, including breast, liver, lung, blood, and prostate cancers. Dr. Osorio Valeriano’s [Philip O'Bryan Montgomery, Jr., MD, Fellow] work will reveal mechanistic aspects of NuRD-mediated chromatin regulation and pave the way for the development of novel therapeutic approaches that target cancers more effectively. Dr. Osorio Valeriano received his PhD from Philipps University and his MSc and BSc from the National Autonomous University of Mexico.