Biology subjects

Samkoe, K. S.

Publications and source records attributed to Samkoe, K. S..

3 recordsLinked to original sources

bioRxiv2024

Endocrine persistence in ER+ breast cancer is accompanied by metabolic vulnerability in oxidative phosphorylation

Despite adjuvant treatment with endocrine therapies, estrogen receptor-positive (ER+) breast cancers recur in a significant proportion of patients. Recurrences are attributable to clinically undetectable endocrine-tolerant persister cancer cells that retain tumor-forming potential. Therefore, strategies targeting such persister cells may prevent recurrent disease. Using CRISPR-Cas9 genome-wide knockout screening in ER+ breast cancer cells, we identified a survival mechanism involving metabolic reprogramming with reliance upon mitochondrial respiration in endocrine-tolerant persister cells. Quantitative proteomic profiling showed reduced levels of glycolytic proteins in persisters. Metabolic tracing of glucose revealed an energy-depleted state in persisters where oxidative phosphorylation was required to generate ATP. A phase II clinical trial was conducted to evaluate changes in mitochondrial markers in primary ER+/HER2-breast tumors induced by neoadjuvant endocrine therapy (NCT04568616). In an analysis of tumor specimens from 32 patients, tumors exhibiting residual cell proliferation after aromatase inhibitor-induced estrogen deprivation with letrozole showed increased mitochondrial content. Genetic profiling and barcode lineage tracing showed that endocrine-tolerant persistence occurred stochastically without genetic predisposition. Mice bearing cell line- and patient-derived xenografts were used to measure the anti-tumor effects of mitochondrial complex I inhibition in the context of endocrine therapy. Pharmacological inhibition of complex I suppressed the tumor-forming potential of persisters and synergized with the anti-estrogen fulvestrant to induce regression of patient-derived xenografts. These findings indicate that mitochondrial metabolism is essential in endocrine-tolerant persister ER+ breast cancer cells and warrant the development of treatment strategies to leverage this vulnerability in the context of endocrine-sensitive disease. Statement of SignificanceEndocrine-tolerant persister cancer cells that survive endocrine therapy can cause recurrent disease. Persister cells exhibit increased energetic dependence upon mitochondria for survival and tumor re-growth potential.

cancer biology↗

bioRxiv2023

Pharmacokinetic profile of the synthetic mu-opioid receptor agonist Dermorphin-IRDye(R)800CW and its feasibility as a biomarker for opioid use disorder

BackgroundOpioid use disorder (OUD) affects more than 14 million Americans and poses a high risk of relapse, overdose, and death. Current treatments are not tailored to individual needs and do not monitor the effectiveness of the medication. We propose a novel method to measure the occupancy of mu opioid receptors (MOR), which are key targets for opioid pharmacotherapy, in peripheral tissues with high MOR density. We developed a fluorescent peptide agonist that binds to MOR and can be detected by non-invasive point-of-care techniques. We present in vitro and in vivo results that demonstrate the feasibility and potential of this method to assess MOR availability and treatment efficacy in OUD patients. MethodsA new fluorescent-labeled synthetic peptide agonist [Lys7]Dermorphin-IRDye800CW, called DRM-800, was synthesized and characterized in vitro to evaluate binding and internalization. Wildtype and MOR knock-out mice were used to quantify plasma kinetics and, using a cyromacrotome, fluorescence images were acquired post-mortem on whole-body sections 150 um apart. These volumes were used to compare in vivo enhancement of MOR-rich structures. ResultsIn vitro assays and microscope visualization of DRM-800 showed high MOR-affinity and rapid, robust internalization. Plasma half-life following intravenous injection in mice was 8-12 minutes. Specific binding by tissue structures of interest, measured by the ratio of relative fluorescent units in wild-type vs. MOR knockout mice showed high binding in dorsal root ganglia, spiral ganglia and trigeminal ganglion, as well as in the small and large intestine. ConclusionsThe pharmacokinetics and distribution, binding kinetics and rapid internalization suggests that MOR-specific fluorescence enhancement corresponding to opioid rich structures could serve as a potential biomarker in opioid use disorder.

bioengineering↗

bioRxiv2023

Stealth liposomes encapsulating a potent ACAT1/SOAT1 inhibitor F12511: pharmacokinetic, biodistribution and toxicity studies in wild-type mice, and efficacy studies in triple transgenic Alzheimer Disease mice.

Cholesterol is essential to cellular function and is stored as cholesteryl esters (CEs). CEs biosynthesis is responsible by the enzymes acyl-CoA: cholesterol acyltransferase 1 and 2 (ACAT1 and ACAT2), with ACAT1 as the primary isoenzyme in most cells in humans. ACATs are targets for atherosclerosis therapies and may also be promising targets for treating Alzheimers Disease (AD). F12511 is a high-affinity ACAT1 inhibitor that has passed phase 1 safety tests for anti-atherosclerosis. Previously, we had developed a nanoparticle system to encapsulate a large concentration of F12511 into a stealth liposome (DSPE-PEG2000 with egg phosphatidylcholine). Here, we injected the nanoparticle encapsulated F12511 (nanoparticle F) intravenously (IV) to wild-type (WT) mice and performed HPLC/MS/MS analysis and ACAT enzyme activity measurement. The results demonstrated that F12511 was present within the mouse brain after a single IV but did not over-accumulate in the brain or other tissues after repeated IVs. Histological examination showed that F12511 did not cause overt neurological or systemic toxicity. We then showed that 2-week IV delivery of nanoparticle F to aging 3xTg AD mice ameliorated amyloidopathy, reduced hyperphosphorylated tau and non-phosphorylated tau, and reduced neuroinflammation. This work lays the foundation with nanoparticle F as a possible therapy for AD and other neurodegenerative diseases.

neuroscience↗