Biology subjects

Black, A. R.

Publications and source records attributed to Black, A. R..

5 recordsLinked to original sources

bioRxiv2026

An Integrated Preclinical Platform for Lethal Neuroendocrine Prostate Cancer from Rapid Autopsy Bone and Liver Metastases.

Treatment-emergent neuroendocrine prostate cancer (NEPC) is an aggressive, therapy-resistant disease arising in up to 20% of castration resistant prostate cancers, yet robust biologically relevant preclinical models remain scarce. Here, we describe a technical blueprint for establishing an integrated platform of patient-derived models from visceral and bone metastases collected through a prostate cancer rapid autopsy program (PC RAP). We report the establishment and characterization of patient-derived xenograft (PDX) models from liver metastasis tissue, liver and bone metastasis-derived organoid lines (PDOs), and corresponding patient-derived organoid xenograft (PDOX) models. In addition, we established, to our knowledge, the first mesenchymal stem cell (MSC) cultures derived from neuroendocrine prostate cancer (NEPC) bone metastases. The PDOs preserved intratumoral heterogeneity, displaying both CRPC-NE and CRPC-adenocarcinoma features. These organoids retained neuroendocrine identity across multiple passages, with transcriptomic profiles concordant with the original patient tissue and matched PDX models generated at our institution and at the National Cancer Institute (NCI Patient-Derived Models Repository). To model the bone metastatic microenvironment, we generated novel organoid-based New Approach Methodologies (NAMs) by co-culturing PDOs with iPSC-derived bone marrow organoids, establishing a physiologically relevant vascularized organotypic model of PC bone metastasis. To extend our studies in vivo, we established preclinical models using the liver and bone metastasis-derived organoid models. The PDOX models were tumorigenic and developed spontaneous lymph node metastases, providing clinically relevant models for investigating lethal NEPC biology. Together, these complementary patient-derived models provide a robust and versatile platform for investigating NEPC biology, metastatic progression, and evaluating new therapeutic strategies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=184 SRC="FIGDIR/small/740121v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@1c641f1org.highwire.dtl.DTLVardef@113696aorg.highwire.dtl.DTLVardef@16dcc72org.highwire.dtl.DTLVardef@1898d9f_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LINovel preclinical models of visceral and bone metastases established from a prostate cancer rapid autopsy program. C_LIO_LIThis study is the first to establish mesenchymal stem cell cultures from NEPC bone metastases. C_LIO_LIPDOs preserve heterogeneity, showing both CRPC-NE and CRPC-Adeno features, with transcriptomic profiles concordant with originator tissue and PDX models. C_LIO_LIPC RAP-derived organoids are tumorigenic in vivo and generate spontaneous lymph node metastases. C_LI

cancer biology↗

bioRxiv2025

PAMD-Ch17, a Polymeric Analog of Plerixafor, Induces Mitochondrial Dysfunction in T-ALL Cells Independent of CXCR4

PAMD-Ch17 is a polymer composed of the CXCR4 inhibitor AMD3100/Plerixafor with a cholesterol modification. In previous work, we showed that PAMD-Ch17, but not AMD3100, induces cell death and differentiation in mouse Acute Myeloid Leukemia cells. To investigate the mechanism of PAMD-Ch17s novel anti-leukemic effects, we tested PAMD-Ch17 against a panel of human leukemia cell lines and found that PAMD-Ch17 is effective against a variety of acute leukemias, with T-ALL cell lines being highly sensitive. Surprisingly, CXCR4 knock out T-ALL cells were equally sensitive to PAMD-Ch17. Using a fluorescently tagged PAMD-Ch17, we found that the drug colocalized to the mitochondria. We also found that PAMD-Ch17 induced changes in expression of genes related to mitochondrial function, increased levels of mitochondrial superoxide, and decreased mitochondrial membrane potential. Using seahorse assays, we found that PAMD-Ch17 decreased baseline oxygen consumption, ATP production, and proton leakage. PAMD-Ch17 also decreased baseline extracellular acidification rate, indicating a decrease in overall metabolism. In mouse primary T-ALL but not healthy bone marrow cells, PAMD-Ch17 induced both mitochondrial superoxide and cell death. Using human bone marrow organoids, we found that PAMD-Ch17 induced mitochondrial superoxide and cell death in human primary T-ALL cells, but not in healthy stromal and hematopoietic cells. Collectively, our results indicate that PAMD-Ch17 has anti-leukemic effects against T-ALL cells but not healthy cells, likely mediated through a CXCR4 independent, mitochondrial based mechanism. These findings support further development of PAMDs as potential therapeutics for patients with T-ALL. KEY POINTSO_LIPAMD-Ch17, a polymeric drug based on AMD3100/Plerixafor, has novel anti-leukemic activities against T-ALL that are independent of CXCR4 inhibition. C_LIO_LIPAMD-Ch17 induces increased mitochondrial superoxide and cell death in primary ALL cells, but not healthy bone marrow cells. C_LI

cancer biology↗

bioRxiv2023

Cbl and Cbl-b Ubiquitin Ligases are Essential for Intestinal Epithelial Stem Cell Maintenance

Among the signaling pathways that control the stem cell self-renewal and maintenance vs. acquisition of differentiated cell fates, those mediated by receptor tyrosine kinase (RTK) activation are well established as key players. CBL family ubiquitin ligases are negative regulators of RTKs but their physiological roles in regulating stem cell behaviors are unclear. While hematopoietic Cbl/Cblb knockout (KO) leads to a myeloproliferative disease due to expansion and reduced quiescence of hematopoietic stem cells, mammary epithelial KO led to stunted mammary gland development due to mammary stem cell depletion. Here, we examined the impact of inducible Cbl/Cblb double-KO (iDKO) selectively in the Lgr5-defined intestinal stem cell (ISC) compartment. Cbl/Cblb iDKO led to rapid loss of the Lgr5Hi ISC pool with a concomitant transient expansion of the Lgr5Lo transit amplifying population. LacZ reporter-based lineage tracing showed increased ISC commitment to differentiation, with propensity towards enterocyte and goblet cell fate at the expense of Paneth cells. Functionally, Cbl/Cblb iDKO impaired the recovery from radiation-induced intestinal epithelial injury. In vitro, Cbl/Cblb iDKO led to inability to maintain intestinal organoids. Single cell RNAseq analysis of organoids revealed Akt-mTOR pathway hyperactivation in iDKO ISCs and progeny cells, and pharmacological inhibition of the Akt-mTOR axis rescued the organoid maintenance and propagation defects. Our results demonstrate a requirement for Cbl/Cblb in the maintenance of ISCs by fine tuning the Akt-mTOR axis to balance stem cell maintenance vs. commitment to differentiation.

cell biology↗

bioRxiv2022

SMALL MOLECULE ACTIVATORS OF B56-PP2A RESTORE 4E-BP EXPRESSION AND FUNCTION TO SUPPRESS CAP-DEPENDENT TRANSLATION IN CANCER CELLS

Dysregulation of cap-dependent translation is a hallmark of cancer, with key roles in supporting the transformed phenotype. The eIF4E binding proteins (4E-BP1, 2, 3) are major negative regulators of cap-dependent translation that are inactivated in tumors through inhibitory phosphorylation by oncogenic kinases (e.g., mTOR) or by downregulation. Previous studies from our group and others have linked tumor suppressive PP2A family serine/threonine phosphatases to activation of 4E-BP1. Here, we leveraged novel small molecule activators of PP2A (SMAPs) (e.g., DT-061, DT-1154) that are being developed as antitumor agents to (a) explore the role of a subset of B56-PP2As in regulation of 4E-BP activity, and (b) to evaluate the potential of B56-PP2A reactivation for restoring translation control in tumor cells. We show that SMAPs promote PP2A-dependent hypophosphorylation of 4E-BP1/4EBP2 in the presence of active upstream inhibitory kinases (mTOR, ERK, AKT), supporting a role for B56-PP2As as 4E-BP phosphatases. Unexpectedly, DT-061 also led to robust PP2A-dependent upregulation of 4E-BP1, but not 4E-BP2 or 4E-BP3. Cap-binding assays and eIF4E immunoprecipitation showed that SMAP/B56-PP2A blocks the formation of the eIF4F translation initiation complex. Bicistronic reporter assays that directly measure cap-dependent translation activity confirmed the translational consequences of these effects. siRNA knockdown pointed to B56-PP2A as a mediator of SMAP effects on 4E-BPs, although B56{beta}- and/or B56{varepsilon}-PP2A may also play a role. 4E-BP1 upregulation involved ATF4-dependent transcription of the 4E-BP1 gene (EIF4EBP1) and the effect was partially dependent on TFE3/TFEB transcription factors. Thus, B56-PP2A orchestrates a translation repressive program involving transcriptional induction and hypophosphorylation of 4E-BP1, highlighting the potential of PP2A-based therapeutic strategies for restoration of translation control in cancer cells.

cancer biology↗

bioRxiv2021

KSR1-and ERK-dependent Translational Regulation of the Epithelial-to-Mesenchymal Transition

The epithelial-to-mesenchymal transition (EMT) is considered a transcriptional process that induces a switch in cells from a polarized state to a migratory phenotype. Here we show that KSR1 and ERK promote EMT through the preferential translation of Epithelial-Stromal Interaction 1 (EPSTI1), which is required to induce the switch from E-to N-cadherin and coordinate migratory and invasive behavior. EPSTI1 is overexpressed in human colorectal cancer (CRC) cells. Disruption of KSR1 or EPSTI1 significantly impairs cell migration and invasion in vitro, and reverses EMT, in part, by decreasing the expression of N-cadherin and the transcriptional repressors of E-cadherin expression, ZEB1 and Slug. In CRC cells lacking KSR1, ectopic EPSTI1 expression restored the E-to N-cadherin switch, migration, invasion, and anchorage-independent growth. KSR1-dependent induction of EMT via selective translation of mRNAs reveals its underappreciated role in remodeling the translational landscape of CRC cells to promote their migratory and invasive behavior.

cancer biology↗