Biology subjects

Walker, B. S.

Publications and source records attributed to Walker, B. S..

3 recordsLinked to original sources

bioRxiv2022

Magnetic Levitation and Sorting of Neoplastic Circulating Cell Hybrids

Circulating hybrid cells (CHCs) are a novel, rare cell population that harbor tumor and immune cell phenotypes and genotypes and are detectible in peripheral blood. Several recent reports implicated CHCs in the metastatic cascade and found their enumeration to provide better prognostic value than conventionally-defined circulating tumor cells (CTCs). However, methods for isolation and enrichment of CHCs are not well-studied or established. Here, we developed an ultrasensitive, antigen-independent platform leveraging the principles of magnetic levitation for the detection and isolation of disseminated neoplastic CHCs. For the first time, we demonstrate that CHCs can be magnetically focused to different levitation heights, under various paramagnetic conditions using a static levitation system, and we quantified the biophysical properties of CHCs (i.e., levitation heights). In addition, we investigated whether magnetic levitation approach can be combined with the affinity-based strategies to enrich CHCs under the magnetic field. Using clinical samples from breast and colorectal cancer patients, we demonstrated that neoplastic cells can be sorted with a magnetic levitation-based sorting device, without relying on any surface markers. Overall, we demonstrated the feasibility of the magnetic levitation method for unbiased enrichment of rare neoplastic-immune hybrid cells from peripheral blood specimens from cancer patients. This approach can be expanded to more clinical samples and cancer types to unprecedentedly explore the biology of rare neoplastic cells and develop metastasis-tailored therapies broadly impacting personalized and precision clinical treatments.

bioengineering↗

bioRxiv2022

Dual states of Bmi1-expressing intestinal stem cells drive epithelial development and tissue regeneration

Intestinal development, response to injury and disease states rely upon balanced stem cell proliferation. Historically, two subtypes of intestinal epithelial stem cells (ISCs)--slow-cycling/label-retaining, and actively-cycling/canonical Wnt-dependent--coordinate to drive proliferation and regulate epithelial renewal during adult tissue homeostasis and injury response. Recent studies focused on Bmi1-expressing cells revealed that differentiated Bmi1+ enteroendocrine cells could dedifferentiate towards a canonical Wnt-dependent stem cell state, calling into question the dogma that a dual stem cell axis regulates epithelial proliferation. Herein, we identify stem cell function in a Bmi1+ cell population in early murine intestinal development prior to the establishment of canonical Wnt-dependent, Lgr5-expressing ISCs. In-depth analyses of developmental Bmi1+ ISCs using lineage-tracing and single cell RNA-sequencing reveal their distinct identity and capacity to differentiate into Lgr5+ ISCs and other differentiated lineages. Further, during in utero development, the Bmi1+ ISCs initially exists in a highly proliferative state then transitions to a slow-cycling state, with the emergence of actively-cycling Lgr5+ ISCs. In adult tissue, Bmi1+ ISCs are a distinct population that re-express developmental gene and protein profiles, and a non-canonical Wnt signaling signature in response to injury and in human colorectal tumors. Further, developmental Bmi1+ ISCs are distinct from Lgr5+ ISCs and the previously identified differentiated Bmi1+ progenitor cells. Re-evaluation of an under-appreciated Bmi1+ ISC population with fundamental importance in intestinal development re-establishes the importance of the dynamic interplay between discrete ISC populations that are regulated by opposing Wnt signaling pathways. This finding opens opportunities and targetable pathways to augment regeneration or inhibit tumorigenesis.

developmental biology↗

bioRxiv2021

Relevance of Circulating Hybrid Cells as a Non-Invasive Biomarker for Myriad Solid Tumors

AbstractMetastatic progression defines the final stages of tumor evolution and underlies the majority of cancer-related deaths. The heterogeneity in disseminated tumor cell populations capable of seeding and growing in distant organ sites contributes to the development of treatment resistant disease. We recently reported the identification of a novel tumor-derived cell population, circulating hybrid cells (CHCs), harboring attributes from both macrophages and neoplastic cells, including functional characteristics important to metastatic spread. These disseminated hybrids outnumber conventionally defined circulating tumor cells (CTCs) in cancer patients. It is unknown if CHCs represent a generalized cancer mechanism for cell dissemination, or if this population is relevant to the metastatic cascade. Herein, we detect CHCs in the peripheral blood of patients with cancer in myriad disease sites encompassing epithelial and non-epithelial malignancies. Further, we demonstrate that in vivo-derived hybrid cells harbor tumor-initiating capacity in murine cancer models and that CHCs from human breast cancer patients express stem cell antigens, features consistent with the ability to seed and grow at metastatic sites. Finally, we reveal heterogeneity of CHC phenotypes reflect key tumor features, including oncogenic mutations and functional protein expression. Importantly, this novel population of disseminated neoplastic cells opens a new area in cancer biology and renewed opportunity for battling metastatic disease. Simple SummaryThere is an incomplete understanding of circulating neoplastic cell populations and the fundamental mechanisms that drive dissemination, immune evasion, and growth --all critical information to more effectively prevent and treat cancer progression. A novel disseminated tumor cell population, circulating hybrid cells, are detected across many cancer types and carry functional tumor-initiating properties. Additionally, circulating hybrid cells are found at significantly higher levels than conventionally defined circulating tumor cells. Our study demonstrates that neoplastic hybrid cells harbor phenotypic and genetic characteristics of tumor and immune cells, display stem features, and are a generalizable phenomenon in solid tumors. Circulating hybrid cells therefore have relevance as a novel biomarker and open a new field of study in malignancy.

cancer biology↗