Biology subjects

Chen, K.-C.

Publications and source records attributed to Chen, K.-C..

10 recordsLinked to original sources

bioRxiv2025

Adiponectin exerts sex-dependent effects on lipid, amino acid, and glucose metabolism during caloric restriction

Adiponectin is the most abundant hormone in the circulation. Plasma adiponectin decreases in obesity but increases in leanness, including during caloric restriction (CR) in animals and humans. In obesity, adiponectin deficiency promotes cardiometabolic dysfunction. In contrast, the roles of adiponectin in CR, when it is at its highest, are largely unknown. To address this, we studied global adiponectin knockout (KO) in male and female mice fed either ad libitum (AL) or a 30% CR diet from 9-13 weeks of age. We show that adiponectin KO did not alter CR effects on body mass, body composition, or energy expenditure. However, KO unexpectedly decreased blood glucose levels during CR, both on fasting and following an oral glucose challenge. This is opposite to the effects of adiponectin deficiency in the context of ad libitum diet (AL) or obesity, and occurred without changes in insulin secretion or sensitivity. Moreover, adiponectin KO augmented CR-induced increases in plasma fatty acids in both sexes and, in males only, impaired systemic triglyceride clearance under CR. Indirect calorimetry further revealed that adiponectin KO alters the shifts between carbohydrate and lipid utilisation that occur during transitions between fed and fasted states. To determine potential molecular mechanisms, we investigated effects of adiponectin KO on the liver, a major adiponectin target that plays key roles entraining metabolism to nutritional state. Hepatic transcriptomics revealed that, in both sexes, adiponectin KO upregulates sterol and fatty acid synthesis genes under AL while increasing amino acid catabolic genes during CR. Together, our findings suggest that adiponectin tunes glucose, lipid, and amino acid metabolism during CR, in whole or in part through effects on the liver. The widely reported functions of adiponectin in pathological states, including obesity and insulin resistance, thus differ sharply from its roles during CR, with marked sexual dimorphism apparent for many of these functions.

physiology↗

bioRxiv2024

WRAD core perturbation impairs DNA replication fidelity promoting immunoediting in pancreatic cancer

It is unclear how cells counteract the potentially harmful effects of uncoordinated DNA replication in the context of oncogenic stress. Here, we identify the WRAD (WDR5/RBBP5/ASH2L/DPY30) core as a modulator of DNA replication in pancreatic ductal adenocarcinoma (PDAC) models. Molecular analyses demonstrated that the WRAD core interacts with the replisome complex, with disruption of DPY30 resulting in DNA re-replication, DNA damage, and chromosomal instability (CIN) without affecting cancer cell proliferation. Consequently, in immunocompetent models, DPY30 loss induced T cell infiltration and immune-mediated clearance of highly proliferating cancer cells with complex karyotypes, thus improving anti-tumor efficacy upon anti-PD-1 treatment. In PDAC patients, DPY30 expression was associated with high tumor grade, worse prognosis, and limited response to immune checkpoint blockade. Together, our findings indicate that the WRAD core sustains genome stability and suggest that low intratumor DPY30 levels may identify PDAC patients who will benefit from immune checkpoint inhibitors.

cancer biology↗

bioRxiv2024

Spatial Transcriptomic Profiling Of Advanced Ovarian Clear Cell Carcinoma Reveals Intra-Tumor Heterogeneity In Epithelial-Mesenchymal Gradient

Intratumoral heterogeneity is intrinsically comprised of molecular alterations of tumor cells and extrinsically from interconnections with microenvironments. This study explores the spatial heterogeneity of ovarian clear cell carcinoma (OCCC), a rare cancer with significance to East Asian women. We profile 21 primary-metastatic tumor pairs in a discovery cohort and 16 tumors in two validation cohorts using spatial transcriptomic (ST) platforms. Our integrative analysis revealed an inverse relationship between OXPHOS and inflammation along the EMT gradient. OCCC cells undergoing partial EMT have metabolic shifts and lose LCN2 expression, possibly via concomitant down-regulation of SOX9. Conversely, LCN2 expression correlated with OXPHOS-enriched tumor signature, low EMT, and better outcomes in OCCC. Single-cell ST profiling using CosMx further identifies nine spatially distinct cancer cell populations including the LCN2-high cancer subclone with a high epithelial score. SOX9 induction could partially restore epithelial-ness in LCN2-low cells suggesting that plasticity in OCCC is achieved via transcriptional reprogramming. Our findings provide further insights into epithelial-mesenchymal plasticity and the adaptive interactions between cancer cells and their microenvironments in OCCC.

cancer biology↗

bioRxiv2024

Inter- and intra-tumor heterogeneous immune presentation in primary uterine carcinosarcoma determined by digital spatial profiling

Uterine carcinosarcoma (UCS) is a rare gynecologic cancer with unfavorable prognosis. Its biphasic histologic components are known to associated with outcomes. Dissecting the tumor heterogeneity within UCS is crucial to discover molecular biomarkers for patient stratification. The aim of this study was to utilize spatial profiling technology to analyze immune presentation in different histological components within UCS tumors. The study included 23 UCS patients whose tumor sections were subjected to nanoString GeoMx Digital Spatial Profiling (DSP) to profile 30 immune-related proteins in 491 segments. We identified distinct cluster-labeled subtypes showing varied immune marker expressions. The immune presentations within the carcinoma and sarcoma components showed significant differences. Markers indicating M2 macrophages (CD45+CD163+) and epithelial-mesenchymal transition (EMT) (SMA, fibronectin) were highly expressed in the sarcoma components. The immune presentation subtypes within each histological component also differed between patients with recurrence in 5 years and without recurrence over 5 years. The cluster-labeled subtype with high Neutrophil/PMN-MDSC marker expression (CD66b) was associated with longer survival, whereas the subtype with high NK cell marker expressions (CD56) was linked to poor prognosis. Our result suggested that immune features within the carcinoma component of UCS tumors would determine patient outcomes and should be considered as a strategy for patient stratification.

immunology↗

bioRxiv2023

Reduced glutamate decarboxylase 1 underlies morphine-promoted lung metastasis of triple-negative breast cancer in mice

IntroductionMorphine is commonly used for cancer-related pain management. Long-term morphine use is not only addictive but also has been associated with risk factor for cancer. MethodsWe intraperitoneally administered morphine to mice for 14 days and then implanted EO771 cells, triple negative breast cancer cells, into their mammary fat pad. After primary tumors were removed on 38th day, a subset of mice were continuously giving saline or morphine until the 68th day. Tumor size, organ metastasis, and tumor RNA expression were analyzed. ResultsOur results revealed that long-term morphine treatment increased lung metastasis in the triple-negative breast cancer mouse model. To determine cellular pathways responsible for morphine-mediated metastasis, we performed RNA sequencing analysis to compare transcriptional profiles during metastasis. Transcriptional analysis revealed a significant number of genes down-regulated by morphine treatment. Based on pathway analysis, we focused on the novel effect of morphine on down-regulating taurine/hypotaurine biosynthesis. Considering that morphine, droperidol (dopamine receptor antagonist), and naloxone (opioid receptor antagonist) may act through opioid receptor or dopamine receptor, we further demonstrated that taurine reduced EO771 cell invasion caused by morphine, but not by droperidol, or naloxone treatment. In addition, morphine treatment significantly reduced the expression of GAD1, one of the enzymes required for biosynthesis of taurine, whereas droperidol and naloxone did not. ConclusionThese novel findings of morphine reduces GAD1 level and taurine reverses invasion suggest that taurine could potentially be employed as a supplement for triple negative breast cancer patients using morphine as pain management. Key MessagesO_LIMorphine usage has been implicated in modulating immune system and affecting cancer progression. C_LIO_LILong-term usage of morphine promotes metastasis of triple negative breast cancer through reducing taurine biosynthesis. C_LIO_LIThese novel findings of morphine reduces GAD1 level and taurine reverses invasion suggest that taurine could potentially be employed as a supplement for triple negative breast cancer patients using morphine as pain management. C_LI

cancer biology↗

bioRxiv2022

New insights into CFTR modulation in reproduction: testicular microenvironment imbalance leads to over-activated caspase signalling in spermatogenesis and adversely affects fertility

Cystic fibrosis transmembrane conductance regulator (CFTR) is a prominent chloride channel that governs mucous secretion in multiple organs, including the reproductive tract. According to earlier reports, defective CFTR results in infertility due to congenital bilateral absence of the vas deferens (CBAVD). However, obstruction in the vas deferens is not the only reason CFTR deficiency causes male infertility. The mechanism underlying the loss of mature sperm owing to CFTR deficiency remains elusive. This study aimed to assess the role of CFTR in spermatogenesis, for which 6- and 8-week-old male mice with Cftr+/+, Cftr+/-, and Cftr-/- genotypes were chosen. Furthermore, we assessed the correlation between CFTR deficiency and delayed development of the reproductive system, anomalous apoptosis activation in spermatogenesis, and ionic alterations of the testis lumen. The results demonstrated that the growth of Cftr-/- mice were delayed, with underweight reproductive organs and mild hypospermatogenesis. CFTR depletion destabilizes spermatogenesis by producing abnormal sperm and triggers activation of the Bax/Bcl-2 ratio in Cftr-/- and Cftr+/-mice, causing caspase-mediated irreversible intrinsic apoptosis. Stage-specific apoptosis in germ cells targeted the sexually mature mice, and the testis microenvironment affirmed that ion concentrations influence sperm capacitation. The blood pH determines apoptosis induction, as CFTR is a bicarbonate transporter. In conclusion, Cftr-/- mice were infertile because CFTR deficiency generated an ionic imbalance in the testis lumen, leading to Bax expression and Bcl-2 blockage, which triggered caspases or further activation of voltage-dependent anion-selective channel 1 (VDAC1). Cumulatively, cytochrome C was released due to altered mitochondrial membrane potential. Eventually, anomalous up-regulated apoptosis activation affected spermatogenesis, thus rendering the Cftr-/- male mice infertile. The results supplied new insights into CFTR modulation in reproduction: an imbalanced testicular microenvironment due to CFTR deficiency affects spermatogenesis and fertility in mice through the overactivation of spermatocyte caspase signalling, thus driving us to focus on updated treatments for CFTR deficiency-caused infertility.

molecular biology↗

bioRxiv2022

Quantification of phosphonate drugs by 1H-31P HSQC shows that rats are better models of primate drug exposure than mice

The phosphonate group is a key pharmacophore in many anti-viral, anti-microbial, and anti-neoplastic drugs. Due to its high polarity and short retention time, detecting and quantifying such phosphonate-containing drugs with LC/MS-based methods is challenging and requires derivatization with hazardous reagents. Given the emerging importance of phosphonate-containing drugs, developing a practical, accessible, and safe method for their quantitation in pharmacokinetics (PK) studies is desirable. NMR-based methods are often employed in drug discovery but are seldom used for compound quantitation in PK studies. Here, we show that proton-phosphorous (1H-31P) heteronuclear single quantum correlation (HSQC) NMR allows for quantitation of the phosphonate-containing enolase inhibitor HEX in plasma and tissue at micromolar concentrations. Although mice were shown to rapidly clear HEX from circulation (over 95% in <1 hr), the plasma half-life of HEX was more than 1hr in rats and nonhuman primates. This slower clearance rate affords a significantly higher exposure of HEX in rat models compared to mouse models while maintaining a favorable safety profile. Similar results were observed for the phosphonate-containing antibiotic, fosfomycin. Our study demonstrates the applicability of the 1H-31P HSQC method to quantify phosphonate-containing drugs in complex biological samples and illustrates an important limitation of mice as preclinical model species for phosphonate-containing drugs.

pharmacology and toxicology↗

bioRxiv2019

High Spatial Resolution Ambient Ionization Mass Spectrometry Imaging Using Microscopy Image Fusion

Mass spectrometry imaging (MSI) using ambient ionization technique enables a direct chemical investigation of biological samples with minimal sample pretreatment. However, detailed morphological information of the sample is often lost due to its limited spatial resolution. In this study, predictive high-resolution molecular imaging was produced by the fusion of ambient ionization MSI with optical microscopy of routine hematoxylin and eosin (H&E) staining produces. Specifically, desorption electrospray ionization (DESI) and nanospray desorption electrospray ionization (nanoDESI) mass spectrometry are employed to visualize lipid and protein species on mice tissue sections. The resulting molecular distributions obtained by ambient ionization MSI-microscopy fusion are verified with matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MSI and immunohistochemistry (IHC) staining. Label-free molecular imaging with 5-m spatial resolution can be acquired using DESI and nanoDESI, whereas the typical spatial resolution of ambient ionization MSI is ~100 m. In this regard, sharpened molecular histology of tissue sections is achieved, providing complementary references to the pathology. Such a multimodality integration enables the discovery of potential tumor biomarkers. After image fusion, more than a dozen of potential biomarkers that could be used to determine the tumor margins on a metastatic mouse lung tissue section and Luminal B breast tumor tissue section are identified.

bioinformatics↗

bioRxiv2018

Nifedipine Modulated Renal Lipogenesis via AMPK-SREBP Transcriptional Pathways

Lipid accumulation in renal cells has been implicated in the pathogenesis of obesity-related kidney disease, and lipotoxicity occurring in the kidney can be a surrogate marker for renal failure or renal fibrosis. Nifedipine-induced renal lipotoxicity has never been cited, although a few studies have shown that nifedipine inhibits lipogenesis via activation of the LKB1-AMPK pathway. Therefore, we utilized NRK52E cell models to examine this further. We pre-treated cells with varying concentrations of nifedipine (7.5, 15, or 30 M) for 24 or 48 h prior to examining the activity of lipogenesis enzymes and lipotoxicity.\n\nNifedipine was found to activate acetyl CoA synthetase, acetyl CoA carboxylase, long chain fatty acyl CoA elongase, ATP-citrate lyase, and HMG CoA reductase, suggesting elevated production of cholesterol, triacylglycerides, and phospholipids. Nifedipine exposure induced a vast accumulation of cytosolic free fatty acids (FFA) and stimulated the production of reactive oxygen species, upregulated CD36 and KIM-1 (kidney injury molecule-1) expression, inhibited p-AMPK activity, and triggered the transcription of SREBP-1/2 and lipin-1, underscoring the potential of nifedipine to induce lipotoxicity with renal damage.\n\nIn the present study, we elucidated the mechanism of action of nifedipine that leads to renal lipotoxicity via the AMPK-SREBP-1/2 pathway. To our knowledge, this is the first report demonstrating nifedipine-induced lipid accumulation in the kidney.

biochemistry↗

bioRxiv2018

Defining Hepatic Modifiers Of ATTR Amyloidosis Through Therapeutic Gene Editing In Patient iPSCs

Systemic amyloidosis represents a class of disorders in which misfolded proteins are secreted by effector organs and deposited as proteotoxic aggregates at downstream target tissues. Despite being well-described clinically, the contribution of effector organs such as the liver to the pathogenesis of these diseases is poorly understood. Here, we utilize a patient-specific induced pluripotent stem cell (iPSC)-based model of hereditary transthyretin (TTR) amyloid disease (ATTR amyloidosis) in order to define the contributions of hepatic cells to the distal proteotoxicity of secreted TTR. To this end, we employ a gene correction strategy to generate isogenic, ATTR amyloidosis patient-specific iPSCs expressing either amyloidogenic or wild-type TTR. We further utilize this gene editing strategy in combination with single cell RNAseq to identify multiple hepatic proteostasis factors, including many components of adaptive unfolded protein response (UPR) signaling pathways, whose expression correlates with the production of destabilized TTR variants in iPSC-derived hepatic cells. We further demonstrate that enhancing ER proteostasis within ATTR amyloidosis iPSC-derived hepatic lineages via stress-independent activation of aforementioned adaptive UPR signaling preferentially reduces the secretion of destabilized amyloidogenic TTR. Together, these results suggest the potential of the liver to chaperone-at-a-distance and impact pathogenesis at downstream target cells in the context of systemic amyloid disease, and further highlight the promise of UPR modulating therapeutics for the treatment of TTR-mediated and other amyloid diseases.

cell biology↗