Biology subjects

Sampathi, S.

Publications and source records attributed to Sampathi, S..

4 recordsLinked to original sources

bioRxiv2023

Zebrafish Drug Screening Identifies Erlotinib as an Inhibitor of Wnt/β-Catenin Signaling and Self-Renewal in T-cell Acute Lymphoblastic Leukemia

The Wnt/{beta}-catenin pathways significance in cancer initiation, progression, and stem cell biology underscores its therapeutic potential, yet clinical application of Wnt inhibitors remains limited due to challenges posed by off-target effects and complex crosstalk with other pathways. In this study, we leveraged the zebrafish model to perform a robust and rapid drug screening of 773 FDA-approved compounds to identify Wnt/{beta}-catenin inhibitors with minimal toxicity. Utilizing zebrafish expressing a Wnt reporter, we identified several drugs that suppressed Wnt signaling without compromising zebrafish development. The efficacy of the top hit, Erlotinib, extended to human cells, where it blocked Wnt/{beta}-catenin signaling downstream of the destruction complex. Notably, Erlotinib treatment reduced self-renewal in human T-cell Acute Lymphoblastic Leukemia cells, which are known to rely on active {beta}-catenin signaling for maintenance of leukemia-initiating cells. Erlotinib also reduced leukemia-initiating cell frequency and delayed disease formation in zebrafish models. This study underscores zebrafishs translational potential in drug discovery and repurposing, and highlights a new use for Erlotinib as a Wnt inhibitor for cancers driven by aberrant Wnt/{beta}-catenin signaling. HighlightsO_LIZebrafish-based drug screening offers an inexpensive and robust platform for identifying compounds with high efficacy and low toxicity in vivo. C_LIO_LIErlotinib, an Epidermal Growth Factor Receptor (EGFR) inhibitor, emerged as a potent and promising Wnt inhibitor with effects in both zebrafish and human cell-based Wnt reporter assays. C_LIO_LIThe identification of Erlotinib as a Wnt inhibitor underscores the value of repurposed drugs in developing targeted therapies to disrupt cancer stemness and improve clinical outcomes C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=42 SRC="FIGDIR/small/555200v1_ufig1.gif" ALT="Figure 1"> View larger version (14K): org.highwire.dtl.DTLVardef@150e0a0org.highwire.dtl.DTLVardef@cb3455org.highwire.dtl.DTLVardef@d8d8a8org.highwire.dtl.DTLVardef@780535_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

Nanopore sequencing methods detect cell-free DNA associated with minimal residual disease and central nervous system infiltration in pediatric Acute Lymphoblastic Leukemia

Acute Lymphoblastic Leukemia (ALL) patients that are positive for minimal residual disease (MRD) after therapy or have leukemic infiltration into the central nervous system (CNS) are considered high risk and receive intensive chemotherapy regimens. Current methods to diagnose MRD and CNS infiltration rely on detecting leukemic cells in patient samples using pathology, flow cytometry, or next-generation sequencing. However, leukemic blasts may persist in the patient but not be physically present in bone marrow biopsy or biofluid sample, leading to inaccurate or delayed patient diagnosis. We have developed a nanopore sequencing workflow to detect B-ALL-associated cell-free DNA (cfDNA) in blood and cerebrospinal fluid (CSF) samples. Quantitation of B-cell specific VDJ recombination events in cfDNA samples defined B-ALL clonal heterogeneity. This workflow allowed us to track the response of individual B-ALL clones throughout treatment. Detection of cfDNA also predicted the clinical diagnosis of MRD and CNS disease. Importantly, we identified patients diagnosed as CNS negative who had low B-cell derived cell-free DNA levels in their CSF sample that correlated with B-cell clones present in the bone marrow. These data suggest that cfDNA assays may be useful in detecting the presence of ALL in the patient even when blasts are not in the biofluid sample. Nanopore analysis of cell-free DNA is a simple, rapid, and inexpensive assay that can serve as a valuable complement to traditional clinical diagnostic approaches for ALL. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=50 SRC="FIGDIR/small/462067v2_ufig1.gif" ALT="Figure 1"> View larger version (12K): org.highwire.dtl.DTLVardef@1373bd3org.highwire.dtl.DTLVardef@138b2e3org.highwire.dtl.DTLVardef@168661forg.highwire.dtl.DTLVardef@1088626_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2020

Impact of Chrysin on Vitamin D and Bone Health - Preclinical Studies

Vitamin D deficiency is an endemic problem existing worldwide. Although several strategies were established to enhance vitamin D3 levels, studies specifically focussing inhibition of vitamin D metabolism which may prolong the availability of active vitamin D in pathological conditions are less explored. Studies also suggest that higher doses of vitamin D3 fail to achieve optimum vitamin D levels. In this context, we focussed on the enzyme CYP3A4 which promotes inactivation of active vitamin D. The current study was aimed to decipher the impact of chrysin, a proven CYP3A4 inhibitor as an intervention and its effects in combination with low dose vitamin D3 (40 IU) and bone health in vitamin D deficiency condition. The in-vivo activity of chrysin was evaluated on female Wistar albino rats fed with a vitamin D deficient diet to attain vitamin D deficiency for 28 days. Chrysin was given alone and in combination with calcium carbonate (CaCO3) and/or vitamin D3. All the therapeutic interventions were assessed for serum 25-OH-D3 by LC-MS, biochemical, urinary, and bone parameters. Animals treated with chrysin alone and in combination with low dose vitamin D3 and/or CaCO3 showed an eminent rise in serum 25-OH-D3 levels along with increased serum biochemical parameters. On contrary, a significant decrease in the urinary parameters followed by beneficial effects on bone parameters was noticed in contrast with the vitamin D deficient diet group. Our findings revealed that although chrysin alone showed a notable effect on 25-OH-D3 and osseous tissue, comparatively it showed intensified therapeutic effect in combination with vitamin D3 and CaCO3 which can be employed as a cost-effective option to improve bone health. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=165 SRC="FIGDIR/small/390757v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@10769corg.highwire.dtl.DTLVardef@db1157org.highwire.dtl.DTLVardef@4f7694org.highwire.dtl.DTLVardef@f20f88_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2020

Mtg16-dependent repression of E protein activity is required for early lymphopoiesis

The ETO/MTG family of transcriptional co-repressors play a key role in adult stem cell functions in various tissues. These factors are commonly found in complex with E proteins such as E2A, HEB, and Lyl1 as well as PRDM14 and BTB/POZ domain factors. Structural studies identified a region in the first domain of MTGs that is conserved in the Drosophila homologue Nervy (Nervy Homology Domain-1, or NHR1) that is essential for ETO/MTG8 to inhibit E protein-dependent transcription. The Cancer Genome Atlas (TCGA) identified cancer associated single nucleotide variants (SNVs) near the MTG16:E protein contact site. We tested these SNVs using sensitive yeast two-hybrid association assays, which suggested that only P209T significantly affected E protein binding. We then used CRISPR-Cas9 and homology directed DNA repair to insert P209T and a known inactivating mutation, F210A, into NHR1 of Mtg16 in the germ line of mice. These mice developed normally, but in competitive bone marrow transplantation assays, the F210A-containing stem cells failed to contribute to lymphopoiesis, while P209T mutant cells were reduced in mature T cell populations. High content fluorescent activated analytical flow cytometry assays identified a defect in the multi-potent progenitor to common lymphoid progenitor transition during lymphopoiesis. These data indicate that the cancer associated changes are likely benign polymorphisms, and the MTG:E protein association is required for lymphopoiesis, but less important for myelopoiesis and stem cell functions.

genetics↗