Cellular Plasticity Research Articles

Abstract PO3-24-12: CRIPTO-regulated extracellular vesicles mediate heterotypic cellular crosstalk in triple negative breast cancers

Abstract Tumor progression involves the dynamic interaction between various cell types within the tumor microenvironment. Fibroblasts, which normally participate in wound healing, exhibit reciprocal communication with breast cancer cells that contributes to tumor cell plasticity and heterogeneity. Gaining insights into the molecular mechanisms underlying cell-to-cell communication, which drive cellular plasticity and play a pivotal role in breast cancer progression and metastasis, has the potential to unlock novel avenues for targeted therapeutic interventions. The small GPI-adaptor protein CRIPTO is a key player in this context. CRIPTO orchestrates the activity of TGF-β and growth factor-like signaling pathways that activate c-Src/MEK/AKT. CRIPTO is expressed during mammary development, wound healing, and breast cancer but is largely undetectable in homeostatic tissue, making it a promising therapeutic target. Our previous studies have demonstrated that the activity of CRIPTO is contingent upon cellular stress, with pronounced influence within pro-fibrotic, hypoxic domains of tumors. Importantly, we have shown that inhibition of CRIPTO using the soluble recombinant protein antagonist A4Fc effectively impedes the progression of triple negative breast cancer (TNBC) in murine xenograft models. Building upon these findings, we have been dissecting CRIPTO‘s role in coordinating fibroblast activation and cell-state reprogramming in TNBC. Notably, we have found that inhibition of CRIPTO with A4Fc suppresses cancer associated fibroblast (CAF) activation and collagen remodeling in vivo. And, by modeling tumor cell:fibroblast crosstalk using in vitro organoid co-cultures, we have demonstrated CRIPTO expression in tumor cells is necessary for extracellular vesicle (EV) uptake by fibroblasts, their SMAD pathway activation and their priming for reciprocal signaling back to tumor cells to for transcriptional reprogramming and cellular invasion. The significance of these findings lies in their potential to pave the way for the development of new therapies specifically targeting crucial tumor cell:fibroblast crosstalk mechanisms at primary and metastatic sites. Plasticity targeting therapies are urgently needed in the treatment of TNBC and other malignancies, and hold great promise for improving patient outcomes. Citation Format: David Freeman, Benjamin Spike, Brooke Gates. CRIPTO-regulated extracellular vesicles mediate heterotypic cellular crosstalk in triple negative breast cancers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-24-12.

Electrophysiology and 3D-imaging reveal properties of human intracardiac neurons and increased excitability with atrial fibrillation.

Altered autonomic input to the heart plays a major role in atrial fibrillation (AF). Autonomic neurons termed ganglionated plexi (GP) are clustered on the heart surface to provide the last point of neural control of cardiac function. To date the properties of GP neurons in humans are unknown. Here we have addressed this knowledge gap in human GP neuron structure and physiology in patients with and without AF. Human right atrial GP neurons embedded in epicardial adipose tissue were excised during open heart surgery performed on both non-AF and AF patients and then characterised physiologically by whole cell patch clamp techniques. Structural analysis was also performed after fixation at both the single cell and at the entire GP levels via three-dimensional confocal imaging. Human GP neurons were found to exhibit unique properties and structural complexity with branched neurite outgrowth. Significant differences in excitability were revealed between AF and non-AF GP neurons as measured by lower current to induce action potential firing, a reduced occurrence of low action potential firing rates, decreased accommodation and increased synaptic density. Visualisation of entire GPs showed almost all neurons are cholinergic with a small proportion of noradrenergic and dual phenotype neurons. Phenotypic distribution differences occurred with AF including decreased cholinergic and dual phenotype neurons, and increased noradrenergic neurons. These data show both functional and structural differences occur between GP neurons from patients with and without AF, highlighting that cellular plasticity occurs in neural input to the heart that could alter autonomic influence on atrial function. KEY POINTS: The autonomic nervous system plays a critical role in regulating heart rhythm and the initiation of AF; however, the structural and functional properties of human autonomic neurons in the autonomic ganglionated plexi (GP) remain unknown. Here we perform the first whole cell patch clamp electrophysiological and large tissue confocal imaging analysis of these neurons from patients with and without AF. Our data show human GP neurons are functionally and structurally complex. Measurements of action potential kinetics show higher excitability in GP neurons from AF patients as measured by lower current to induce action potential firing, reduced low firing action potential rates, and decreased action potential accommodation. Confocal imaging shows increased synaptic density and noradrenergic phenotypes in patients with AF. Both functional and structural differences occur in GP neurons from patients with AF that could alter autonomic influence on atrial rhythm.

Transient Interphase Microtubules Appear in Differentiating Sponge Cells

Microtubules are an indispensable component of all eukaryotic cells due to their role in mitotic spindle formation, yet their organization and number can vary greatly in the interphase. The last common ancestor of all eukaryotes already had microtubules and microtubule motor proteins moving along them. Sponges are traditionally regarded as the oldest animal phylum. Their body does not have a clear differentiation into tissues, but it contains several distinguishable cell types. The choanocytes stand out among them and are responsible for creating a flow of water with their flagella and increasing the filtering and feeding efficiency of the sponge. Choanocyte flagella contain microtubules, but thus far, observing a developed system of cytoplasmic microtubules in non-flagellated interphase sponge cells has been mostly unsuccessful. In this work, we combine transcriptomic analysis, immunofluorescence, and electron microscopy with time-lapse recording to demonstrate that microtubules appear in the cytoplasm of sponge cells only when transdifferentiation processes are activated. We conclude that dynamic cytoplasmic microtubules in the cells of sponges are not a persistent but rather a transient structure, associated with cellular plasticity.

Recent contributions of single-cell and spatial profiling to the understanding of bladder cancer.

Current risk stratification and treatment decision-making for bladder cancer informed by histopathology as well as molecular diagnostics face limitations. This review summarizes recent advancements in single-cell and spatial omics methodologies for understanding bladder cancer biology and their potential impact on development of novel therapeutic strategies. Single-cell RNA sequencing and spatial omics techniques offer unprecedented insights into various aspects of tumor microenvironment (TME), bladder cancer heterogeneity, cancer stemness, and cellular plasticity. Studies have identified multiple malignant cell subpopulations within tumors, revealing diverse transcriptional states and clonal evolution. Additionally, intratumor heterogeneity has been linked to tumor progression and therapeutic response. Immune cell composition analysis has revealed immunosuppressive features in the TME, impacting treatment response. Furthermore, studies have elucidated the role of cancer-associated fibroblasts and endothelial cells in shaping the tumor immune landscape and response to therapy. Single-cell and spatial omics technologies have revolutionized our understanding of bladder cancer biology, uncovering previously unseen complexities. These methodologies provide valuable insights into tumor heterogeneity and microenvironmental interactions, with implications for therapeutic development. However, challenges remain in translating research findings into clinical practice and implementing personalized treatment strategies. Continued interdisciplinary collaboration and innovation are essential for overcoming these challenges and leveraging the full potential of single-cell and spatial omics in improving bladder cancer diagnosis and treatment.

Zeb1-controlled metabolic plasticity enables remodeling of chromatin accessibility in the development of neuroendocrine prostate cancer.

Cell plasticity has been found to play a critical role in tumor progression and therapy resistance. However, our understanding of the characteristics and markers of plastic cellular states during cancer cell lineage transition remains limited. In this study, multi-omics analyses show that prostate cancer cells undergo an intermediate state marked by Zeb1 expression with epithelial-mesenchymal transition (EMT), stemness, and neuroendocrine features during the development of neuroendocrine prostate cancer (NEPC). Organoid-formation assays and in vivo lineage tracing experiments demonstrate that Zeb1+ epithelioid cells are putative cells of origin for NEPC. Mechanistically, Zeb1 transcriptionally regulates the expression of several key glycolytic enzymes, thereby predisposing tumor cells to utilize glycolysis for energy metabolism. During this process, lactate accumulation-mediated histone lactylation enhances chromatin accessibility and cellular plasticity including induction of neuro-gene expression, which promotes NEPC development. Collectively, Zeb1-driven metabolic rewiring enables the epigenetic reprogramming of prostate cancer cells to license the adeno-to-neuroendocrine lineage transition.

A comprehensive review: synergizing stem cell and embryonic development knowledge in mouse and human integrated stem cell-based embryo models

Mammalian stem cell-based embryo models have emerged as innovative tools for investigating early embryogenesis in both mice and primates. They not only reduce the need for sacrificing mice but also overcome ethical limitations associated with human embryo research. Furthermore, they provide a platform to address scientific questions that are otherwise challenging to explore in vivo. The usefulness of a stem cell-based embryo model depends on its fidelity in replicating development, efficiency and reproducibility; all essential for addressing biological queries in a quantitative manner, enabling statistical analysis. Achieving such fidelity and efficiency requires robust systems that demand extensive optimization efforts. A profound understanding of pre- and post-implantation development, cellular plasticity, lineage specification, and existing models is imperative for making informed decisions in constructing these models. This review aims to highlight essential differences in embryo development and stem cell biology between mice and humans, assess how these variances influence the formation of partially and fully integrated stem cell models, and identify critical challenges in the field.

Circulating tumor cells with metastasis-initiating competence survive fluid shear stress during hematogenous dissemination through CXCR4-PI3K/AKT signaling

To seed lethal secondary lesions, circulating tumor cells (CTCs) must survive all rate-limiting factors during hematogenous dissemination, including fluid shear stress (FSS) that poses a grand challenge to their survival. We thus hypothesized that CTCs with the ability to survive FSS in vasculature might hold metastasis-initiating competence. This study reported that FSS of physiologic magnitude selected a small subpopulation of suspended tumor cells in vitro with the traits of metastasis-initiating cells, including stemness, migration/invasion potential, cellular plasticity, and biophysical properties. These shear-selected cells generated local and metastatic tumors at the primary and distal sites efficiently, implicating their metastasis competence. Mechanistically, FSS activated the mechanosensitive protein CXCR4 and the downstream PI3K/AKT signaling, which were essential in shear-mediated selection of metastasis-competent CTCs. In summary, these findings conclude that CTCs with metastasis-initiating competence survive FSS during hematogenous dissemination through CXCR4-PI3K/AKT signaling, which may provide new therapeutic targets for the early prevention of tumor metastasis.

The epigenetic landscape in intestinal stem cells and its deregulation in colorectal cancer.

Epigenetic mechanisms play a pivotal role in controlling gene expression and cellular plasticity in both normal physiology and pathophysiological conditions. These mechanisms are particularly important in the regulation of stem cell self-renewal and differentiation, both in embryonic development and within adult tissues. A prime example of this finely tuned epigenetic control is observed in the gastrointestinal lining, where the small intestine undergoes renewal approximately every 3-5 days. How various epigenetic mechanisms modulate chromatin functions in intestinal stem cells (ISCs) is currently an active area of research. In this review, we discuss the main epigenetic mechanisms that control ISC differentiation under normal homeostasis. Furthermore, we explore the dysregulation of these mechanisms in the context of colorectal cancer (CRC) development. By outlining the main epigenetic mechanisms contributing to CRC, we highlight the recent therapeutics development and future directions for colorectal cancer research.

Single-cell multiomics reveals the interplay of clonal evolution and cellular plasticity in hepatoblastoma

Hepatoblastomas (HB) display heterogeneous cellular phenotypes that influence the clinical outcome, but the underlying mechanisms are poorly understood. Here, we use a single-cell multiomic strategy to unravel the molecular determinants of this plasticity. We identify a continuum of HB cell states between hepatocytic (scH), liver progenitor (scLP) and mesenchymal (scM) differentiation poles, with an intermediate scH/LP population bordering scLP and scH areas in spatial transcriptomics. Chromatin accessibility landscapes reveal the gene regulatory networks of each differentiation pole, and the sequence of transcription factor activations underlying cell state transitions. Single-cell mapping of somatic alterations reveals the clonal architecture of each tumor, showing that each genetic subclone displays its own range of cellular plasticity across differentiation states. The most scLP subclones, overexpressing stem cell and DNA repair genes, proliferate faster after neo-adjuvant chemotherapy. These results highlight how the interplay of clonal evolution and epigenetic plasticity shapes the potential of HB subclones to respond to chemotherapy.

Adipose tissue plasticity mediated by the counterregulatory axis of the renin-angiotensin system: Role of Mas and MrgD receptors.

The renin-angiotensin system (RAS) is an endocrine system composed of two main axes: the classical and the counterregulatory, very often displaying opposing effects. The classical axis, primarily mediated by angiotensin receptors type 1 (AT1R), is linked to obesity-associated metabolic effects. On the other hand, the counterregulatory axis appears to exert antiobesity effects through the activation of two receptors, the G protein-coupled receptor (MasR) and Mas-related receptor type D (MrgD). The local RAS in adipose organ has prompted extensive research into white adipose tissue and brown adipose tissue (BAT), with a key role in regulating the cellular and metabolic plasticity of these tissues. The MasR activation favors the brown plasticity signature in the adipose organ by improve the thermogenesis, adipogenesis, and lipolysis, decrease the inflammatory state, and overall energy homeostasis. The MrgD metabolic effects are related to the maintenance of BAT functionality, but the signaling remains unexplored. This review provides a summary of RAS counterregulatory actions triggered by Mas and MrgD receptors on adipose tissue plasticity. Focus on the effects related to the morphology and function of adipose tissue, especially from animal studies, will be given targeting new avenues for treatment of obesity-associated metabolic effects.

Abstract LB224: Neoplastic immune mimicry potentiates breast cancer progression

Abstract Dedifferentiation programs are commonly enacted during breast cancer progression where they enable novel cellular phenotypes. Increased cellular plasticity within the neoplastic compartment of tumors correlates with disease aggressiveness, often manifesting as greater resistance to cytotoxic therapies or increased ability to metastasize to distant organs. Here we report that subpopulations of ostensibly stem-like neoplastic breast epithelial cells express canonical leukocyte cell surface receptor proteins, and have named this unique cellular program ‘immune mimicry’ (IM). We have documented neoplastic cells engaging in IM by examination of histopathological breast tumor specimens and their derived cell lines, public human breast tumor single-cell RNA-seq datasets, and in murine transgenic and cell line-derived mammary cancer models. Immune-mimicked neoplastic cells harbor hallmarks of dedifferentiation and appear enriched for developing aggressive and high-grade tumors. Experimental studies with breast cancer cell lines revealed that neoplastic cells expressing leukocyte surface features are elicited by growth-arresting conditions, such as conventional cytotoxic chemotherapeutic treatments and during metastatic dissemination in mice. In addition, using proof-of-concept studies, we leveraged the canonical leukocyte activation marker CD69, to demonstrate how its expression by neoplastic epithelial cells confers a proliferative advantage under low-density conditions. We conclude that neoplastic breast epithelial cells expressing leukocyte surface receptors may signify a particularly malignant and tumor-initiating cell state. Moving forward, neoplastic IM will be evaluated for prognostic utility in breast cancer to determine whether this unique cell state stratifies patients with increased risks for tumor recurrence and metastasis. The authors acknowledge NIH/NCI (K00 CA212132, T32 CA254888, P30 CA069533), the Collins Medical Trust, the Susan G Komen Foundation, and the National Foundation for Cancer Research for funding. Citation Format: Eric B. Berens, Sokchea Khou, Elaine Huang, Amber Hoffman, Briana Johnson, Zena Werb, Laura M. Heiser, Lisa M. Coussens. Neoplastic immune mimicry potentiates breast cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB224.

Abstract LB223: The molecular landscape of injury-induced mammary epithelial cell fate switching

Abstract The most aggressive cancers, such as triple negative basal-like breast cancer (TNBC), have high intratumoral heterogeneity that is often attributed to cell state reprogramming and contributes to cancer progression, treatment resistance, and ultimately cancer death. Tissue injury and microenvironmental changes can cause adult differentiated cells to acquire a plastic “developmentally unstable hybrid cell state” (DUHCS) enabling transdifferentiation into other cell types to effect repair. Yet, the relevant mechanisms that enable cell state reprogramming to arise remain under-explored. Here, we used CRISPR mediated homologous recombination to generate mice in which the mammary basal and luminal cells could be distinguished by their expression of Krt14-mClover-NLS or Krt18-tdTomato-NLS, respectively. We used this novel system to identify mammary epithelial cells undergoing cell state transitions in real time. Using a transplantation paradigm, we found that transplanted basal cells rapidly exhibited a DUHCS resembling mammary embryonic progenitors expressing Sox11, a tightly regulated differentiation factor shut off before birth. We discovered that Sox11 is also expressed in many murine models of TNBC and in single cell transcriptomes from untreated human BRCA1 mutant TNBCs. This suggests that Sox11-expressing cells might be developmentally plastic intermediates in TNBC malignant progression. In a preliminary cohort of patient-derived xenografts from TNBC patients diagnosed at different stages, we detected SOX11-expressing cells in earlier but not in advanced stages. Re-expression of Sox11 in TNBC is consistent with TNBCs being transcriptomically related to fetal mammary stem cells and p53 dysfunction resulting in enhanced cellular plasticity. Taken together, these studies highlight a role for mammary epithelial cell state reprogramming in early breast tumorigenesis, and reveals actionable steps to mitigate tumor heterogeneity by halting tumor progression. Citation Format: Queralt Vallmajó Martín, Nikki K. Lytle, Divya Murali, Sumana Srinivasan, Zhibo Ma, Kavitha Mukund, Christopher Dravis, Liliana Zamora, Ana Peterson, Galina Khramtsova, Funmi Olopade, Shankar Subramaniam, Geoffrey M. Wahl. The molecular landscape of injury-induced mammary epithelial cell fate switching [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB223.

Cellular plasticity in the breast cancer ecosystem.

The complex interplay between genetically diverse tumor cells and their microenvironment significantly influences cancer progression and therapeutic responses. This review highlights recent findings on cellular plasticity and heterogeneity within the breast cancer ecosystem, focusing on the roles of cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). We discuss evidence suggesting that breast cancer cells exhibit phenotypic plasticity driven by both intrinsic genetic factors and external microenvironmental cues, impacting treatment responses and disease recurrence. Moreover, single-cell RNA sequencing studies reveal diverse subtypes of CAFs and TAMs, each with distinct functional gene expression programs and spatial organization within the tumor microenvironment. Understanding the hierarchical relationships and niche cues governing cellular phenotypes offers new opportunities for targeted therapeutic interventions. By elucidating the organizational principles of the tumor ecosystem, future therapies may target phenotypic states or entire cellular niches, advancing precision medicine approaches in breast cancer treatment.

High-Throughput Transcriptomics of Nontumorigenic Breast Cells Exposed to Environmentally Relevant Chemicals.

There is a suite of chemicals, including metals, pesticides, and personal care product compounds, which are commonly detected at high levels in US Center for Disease Control's National Health and Nutrition Examination Survey (NHANES) chemical biomarker screens. Whether these chemicals influence development of breast cancer is not well understood. The objectives were to perform an unbiased concentration-dependent assessment of these chemicals, to quantify differences in cancer-specific genes and pathways, to describe if these differences occur at human population-relevant concentrations, and to specifically test for differences in markers of stemness and cellular plasticity. We treated nontumorigenic mammary epithelial cells, MCF10A, with 21 chemicals at four concentrations (, , , and ) for 48 h. We conducted RNA-sequencing for these 408 samples, adapting the plexWell plate-based RNA-sequencing method to analyze differences in gene expression. We calculated gene and biological pathway-specific benchmark concentrations (BMCs) using BMDExpress3, identifying differentially expressed genes and generating the best fit benchmark concentration models for each chemical across all genes. We identified enriched biological processes and pathways for each chemical and tested whether chemical exposures change predicted cell type distributions. We contextualized benchmark concentrations relative to human population biomarker concentrations in NHANES. We detected chemical concentration-dependent differences in gene expression for thousands of genes. Enrichment and cell type distribution analyses showed benchmark concentration responses correlated with differences in breast cancer-related pathways, including induction of basal-like characteristics for some chemicals, including arsenic, lead, copper, and methyl paraben. Comparison of benchmark data to NHANES chemical biomarker (urine or blood) concentrations indicated an overlap between exposure levels and levels sufficient to cause a gene expression response. These analyses revealed that many of these 21 chemicals resulted in differences in genes and pathways involved in breast cancer in vitro at human exposure-relevant concentrations. https://doi.org/10.1289/EHP12886.

Assessment of the therapeutic potential of a novel phosphoramidate acyclic nucleoside on induced hepatocellular carcinoma in rat model

AimsHepatocellular Carcinoma (HCC) is renowned as a deadly primary cancer of hepatic origin. Sorafenib is the drug-of-choice for targeted treatment of unresectable end-stage HCC. Unfortunately, great proportion of HCC patients showed intolerance or unresponsiveness to treatment. This study assesses potency of novel ProTide; SH-PAN-19 against N-Nitrosodiethylamine (DEN)-induced HCC in male Wistar rats, compared to Sorafenib. Main methodsStructural entity of the synthesized compound was substantiated via FT-IR, UV–Vis, 1H NMR and 13C NMR spectroscopic analysis. In vitro, SH-PAN-19 cytotoxicity was tested against 3 human cell lines; hepatocellular carcinoma; HepG-2, colorectal carcinoma; HCT-116 and normal fibroblasts; MRC-5. In vivo, therapeutic efficacy of SH-PAN-19 (300 mg/kg b.w./day) against HCC could be revealed and compared to that of Sorafenib (15 mg/kg b.w./day) by evaluating the morphometric, biochemical, histopathological, immunohistochemical and molecular key markers. Key findingsSH-PAN-19 was relatively safe toward MRC-5 cells (IC50 = 307.6 μg/mL), highly cytotoxic to HepG-2 cells (IC50 = 24.9 μg/mL) and prominently hepato-selective (TSI = 12.35). Oral LD50 of SH-PAN-19 was >3000 mg/kg b.w. DEN-injected rats suffered hepatomegaly, oxidative stress, elevated liver enzymes, hypoalbuminemia, bilirubinemia and skyrocketed AFP plasma titre. SH-PAN-19 alleviated the DEN-induced alterations in apoptotic, angiogenic and inflammatory markers. SH-PAN-19 produced a 2.5-folds increase in Caspase-9 and downregulated VEGFR-2, IL-6, TNF-α, TGFβ-1, MMP-9 and CcnD-1 to levels comparable to that elicited by Sorafenib. SH-PAN-19 resulted in near-complete pathological response versus partial response achieved by Sorafenib. SignificanceThis research illustrated that SH-PAN-19 is a promising chemotherapeutic agent capable of restoring cellular plasticity and could stop HCC progression.

SIX2 promotes cell plasticity via Wnt/β-catenin signalling in androgen receptor independent prostate cancer.

The use of androgen receptor (AR) inhibitors in prostate cancer gives rise to increased cellular lineage plasticity resulting in resistance to AR-targeted therapies. In this study, we examined the chromatin landscape of AR-positive prostate cancer cells post-exposure to the AR inhibitor enzalutamide. We identified a novel regulator of cell plasticity, the homeobox transcription factor SIX2, whose motif is enriched in accessible chromatin regions after treatment. Depletion of SIX2 in androgen-independent PC-3 prostate cancer cells induced a switch from a stem-like to an epithelial state, resulting in reduced cancer-related properties such as proliferation, colony formation, and metastasis both in vitro and in vivo. These effects were mediated through the downregulation of the Wnt/β-catenin signalling pathway and subsequent reduction of nuclear β-catenin. Collectively, our findings provide compelling evidence that the depletion of SIX2 may represent a promising strategy for overcoming the cell plasticity mechanisms driving antiandrogen resistance in prostate cancer.

Quantity, distribution and phenotype of newly generated cells in the intact spinal cord of adult macaque monkeys

The existence of proliferating cells in the intact spinal cord, their distribution and phenotype, are well studied in rodents. A limited number of studies also address the proliferation after spinal cord injury, in non-human primates. However, a detailed description of the quantity, distribution and phenotype of proliferating cells at different anatomical levels of the intact adult non-human primate spinal cord is lacking at present. In the present study, we analyzed normal spinal cord tissues from adult macaque monkeys (Macaca fuscata), infused with Bromo-2′-deoxyuridine (BrdU), and euthanized at 2h, 2 weeks, 5 weeks and 10 weeks after BrdU. We found a significantly higher density of BrdU + cells in the gray matter of cervical segments as compared to thoracic or lumbar segments, and a significantly higher density of proliferating cells in the posterior as compared to the anterior horn of the gray matter. BrdU + cells exhibited phenotype of microglia or endothelial cells (∼50%) or astroglial and oligodendroglial cells (∼40%), including glial progenitor phenotypes marked by the transcription factors Sox9 and Sox10. BrdU + cells also co-expressed other transcription factors known for their involvement in embryonic development, including Emx2, Sox1, Sox2, Ngn1, Olig1, Olig2, Olig3. In the central canal, BrdU + cells were located along the dorso-ventral axis and co-labeled for the markers Vimentin and Nestin. These results reveal the extent of cellular plasticity in the spinal cord of non-human primates under normal conditions.

PP2B-Dependent Cerebellar Plasticity Sets the Amplitude of the Vestibulo-ocular Reflex during Juvenile Development.

Throughout life, the cerebellum plays a central role in the coordination and optimization of movements, using cellular plasticity to adapt a range of behaviors. Whether these plasticity processes establish a fixed setpoint during development, or continuously adjust behaviors throughout life, is currently unclear. Here, by spatiotemporally manipulating the activity of protein phosphatase 2B (PP2B), an enzyme critical for cerebellar plasticity in male and female mice, we examined the consequences of disrupted plasticity on the performance and adaptation of the vestibulo-ocular reflex (VOR). We find that, in contrast to Purkinje cell (PC)-specific deletion starting early postnatally, acute pharmacological as well as adult-onset genetic deletion of PP2B affects all forms of VOR adaptation but not the level of VOR itself. Next, we show that PC-specific genetic deletion of PP2B in juvenile mice leads to a progressive loss of the protein PP2B and a concurrent change in the VOR, in addition to the loss of adaptive abilities. Finally, re-expressing PP2B in adult mice that lack PP2B expression from early development rescues VOR adaptation but does not affect the performance of the reflex. Together, our results indicate that chronic or acute, genetic, or pharmacological block of PP2B disrupts the adaptation of the VOR. In contrast, only the absence of plasticity during cerebellar development affects the setpoint of VOR, an effect that cannot be corrected after maturation of the cerebellum. These findings suggest that PP2B-dependent cerebellar plasticity is required during a specific period to achieve the correct setpoint of the VOR.

Abstract 1988: Mass spectrometry profiling identifies ENO2 as a driver of lenvatinib resistance in hepatocellular carcinoma

Abstract Hepatocellular carcinoma (HCC) is the predominant type of primary liver cancer, and lenvatinib is a multi-kinase inhibitor approved by the FDA as a first-line drug for advanced HCC since 2018. Lenvatinib demonstrated antitumor activity with a higher objective response rate, longer progression-free survival, and time to progression in a non-inferiority trial compared with sorafenib. However, the clinical benefits of lenvatinib remain limited as acquired resistance to lenvatinib during HCC treatment is inevitable. This highlights the need to understand the molecular mechanisms of lenvatinib resistance and to explore new therapeutic approaches to overcome this resistance. Tumor lineage plasticity, a recognized hallmark of cancer, is a phenomenon in which tumor cells dedifferentiate into a more stemness state to attain cellular plasticity, enabling them to evade targeted therapeutic interventions. However, the mechanism by which cellular plasticity contributes to lenvatinib resistance remains elusive. In this study, we employed proteomic mass spectrometry to investigate altered proteins in two pairs of parental lenvatinib-sensitive and their corresponding trained lenvatinib-resistant HCC cell lines. This analysis revealed that upregulation of enolase 2 (ENO2), a glycolytic enzyme that catalyzes the dehydration and conversion of 2-phosphoglycerate to phosphoenolpyruvate, is a critical contributor. ENO2 upregulation is frequently observed in HCC and is strongly correlated with aggressive clinical features, including poor survival, advanced tumor stage, and poor differentiation status. We further showed that ENO2 upregulation in HCC is positively correlated with stemness and hepatic progenitor marker signatures, as well as hypoxia, and subsequently demonstrated that ENO2 is regulated by hypoxia/HIF-1α, with hypoxia response element sequences located in the ENO2 promoter region. Research is underway to investigate the functional role and underlying molecular mechanisms associated with ENO2-driven lenvatinib resistance and cellular plasticity in HCC. Citation Format: Sukbum Kim, Jia-Jian Loh, Huajian Yu, Ki-Fong Man, Kai-Yu Ng, Terence Kin-Wah Lee, Clive Yik-Sham Chung, Stephanie Ma. Mass spectrometry profiling identifies ENO2 as a driver of lenvatinib resistance in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1988.

Abstract 903: AURIGIN: A comprehensive single-cell OMICs atlas of human development and an AI/ML framework to classify and identify the drivers of tumor plasticity and altered cellular state

Abstract Altered cellular state and plasticity have been increasingly identified as drivers of poor prognosis and treatment-resistance in cancer. Identifying therapeutics that correct altered cellular state and plasticity meets a broad need in the field of oncology, particularly in tumors resistant to standard-of-care therapy. Tumor plasticity and altered cellular states encompass many potential configurations, including dedifferentiated and transdifferentiated tumors, so classifying tumors based on their specific cell state profile is critical to identifying the gene drivers that are specific to that altered state. For that reason, we have developed AURIGIN - a platform that combines a comprehensive single-cell OMICs atlas of human development with an AI/ML framework that can classify cell state plasticity and identify the genes and pathways that drive those specific altered cellular states. AURIGIN is more comprehensive than previously disclosed single cell atlases in that it focuses and enriches the diverse stem, progenitor, and developmental states commonly involved in plastic cell states of cancer. The platform standardizes and integrates these states with multiple atlases of differentiated adult tissues to create a unified atlas of human development. In addition, the AI/ML paradigm of AURIGIN is embedded with developmental biology models that enable it to deconvolute state heterogeneity within tumor indications for precise identification of the most relevant gene targets for novel therapies. AURIGIN also unifies classified plasticity across tissue types by identifying altered cellular states that span multiple indications. Furthermore, we present the implementation of AURIGINDRIVE ML models that integrate pathway information, physical interaction datasets, and regulatory annotations to accurately predict the gene targets at the top of hierarchy of control of tumor plasticity. AURIGIN also enables and accelerates target validation by identifying models that map to the relevant classified plastic states. Similarly, AURIGIN defines clinically relevant patient selection and treatment efficacy biomarkers that are specifically defined from the classified plastic cellular state. We demonstrate the success of AURIGIN for therapeutic discovery. In sum, AURIGIN amplifies the value of multiOMIC tumor data in cellular state and plasticity target discovery by mapping the data into a developmental biology-informed ML framework. Citation Format: Joseph DeBartolo, Henry Wilson, Kimberly S. Straley, Maulasri Bhatta, Sambad Sharma, Sara Sinicropi-Yao, James Neef, Betty Chan, Andrew McRiner, Mark Bittinger, Laura Antipov, Katharine E. Yen, Thomas G. Graeber, David S. Millan. AURIGIN: A comprehensive single-cell OMICs atlas of human development and an AI/ML framework to classify and identify the drivers of tumor plasticity and altered cellular state [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 903.