Cancer starts years to decades before diagnosis. Yet, early stages of tumor development are poorly understood. In particular, the precancer landscape of chromosome instability (CIN) is understudied, due to the scarcity of precursor lesions and methods to analyze CIN in single cells. The research presented here will address how the instability rate of the genome, followed by selection, determines whether a CIN-driven tumor arises. I hypothesize that the onset of CIN is the tipping point that governs the fate of a precancer clone. Using spatially aware and single-cell multiome methods that we developed, we will dissect essential factors that lead to malignancy via CIN, including extrachromosome circular DNAs. We will analyze two solid tissues at opposite ends of the cell turnover spectrum, which deeply diverge in regeneration capacity, clonality and constraints, namely the brain and the gut. Aim 1 will assess the instability rate of the human genome using the postmortem brain as a model tissue. CIN patterns vary greatly in frequency and type across brain tumors; we will compare the background incidence of fundamental types of CIN in normal cells to CIN signatures after selection has acted, in diagnosed tumors of the same lineages. Aim 2 will dissect CIN in space and time from the cell of origin, to identify what discriminates nascent clones that may cause cancer from those that do not. Timecourses in mouse models will reveal how CIN contributes to selective advantages and how nascent CIN-positive clones escape elimination by immune cells. Aim 3 leverages human precursor lesions to probe the role of CIN as a central gatekeeper between tumor initiation and growth, using the gut as a longitudinal in vivo system to directly capture the tipping point to cancer. Unstable Genome will provide the first systematic quantification of the early development of chromosomally unstable lesions and reveal the principles that govern CIN-driven clone expansion in vivo.

My lab studies how cells regulate their growth and metabolism during normal development and in disease. Recent work in my lab, published last year in Nature, identified the metabolite stearic acid (C18:0) as a novel regulator of mitochondrial function. We showed that dietary C18:0 acts via a novel signaling route whereby it covalently modifies the cell-surface Transferrin Receptor (TfR1) to regulate mitochondrial morphology. We found that modification of TfR1 by C18:0 ('stearoylation') is analogous to protein palmitoylation by C16:0 - it is a covalent thio-ester link and requires a transferase enzyme. This work made two conceptual contributions. 1) It uncovered a novel signaling route regulating mitochondrial function. 2) Relevant to this grant application, we found by mass spectrometry multiple other proteins that are stearoylated in mammalian cells. This thereby opens a new avenue of research, suggesting that C18:0 signals via several target proteins to regulate cellular growth and metabolism. I propose here to study this C18:0 signaling. To study C18:0 signaling we will exploit tools recently developed in my lab to 1) identify as complete a set as possible of proteins that are stearoylated in human and Drosophila cells, thereby characterizing the cellular 'stearylome', 2) study how stearoylation affects the molecular function of these target proteins, and thereby cellular growth and metabolism, and 3) study how stearoylation is added, and possibly removed, from target proteins. This work will change the way we view C18:0 from simply being a metabolite to being an important dietary signaling molecule that links nutritional uptake to cellular physiology. Via unknown mechanisms, dietary C18:0 is clinically known to have special properties for cardiovascular risk. Hence this proposal, discovering how C18:0 signals to regulate cells, will have implications for both normal development and for disease.

Biological soft tissues, such as brain tissues, present a major challenge for wireless biomedical microdevices to penetrate, due to the complex anatomy and viscoelastic mechanical properties. Parasitic organisms can penetrate plant roots using a hardened stylet while navigating with the soft body undulation. The combination of the rigid and soft biological morphology allows these parasites to fracture, anchor to, and extract nutrients from the plant cells. Inspired by these parasites, I propose a novel microrobot with a stiff head and a flexible body designed to penetrate brain tissue, enabling the treatment of hard-to-treat brain cancers, such as glioblastoma. These cancer regions are often inaccessible to large surgical tools due to their critical functional importance. In this project, the microrobot will be fabricated using two-photon lithography to achieve precise micro-scale features. Theoretical modeling and finite element analysis will be employed to explore the robot-tissue interactions, optimizing the design and actuation parameters. The propulsion will be validated in hydrogel models and ex vivo animal experiments. This research aims to develop new microrobots for glioblastoma treatment, paving the way for innovative minimally-invasive medical procedures.