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22 result(s) for "Liu, Bee Hui"
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Targeting transcription factors through an IMiD independent zinc finger domain
Immunomodulatory imide drugs (IMiDs) degrade specific C2H2 zinc finger degrons in transcription factors, making them effective against certain cancers. SALL4, a cancer driver, contains seven C2H2 zinc fingers in three clusters, including an IMiD degron in zinc finger cluster one (ZFC1). Surprisingly, IMiDs do not inhibit the growth of SALL4-expressing cancer cells. To overcome this limit, we focused on a non-IMiD domain, SALL4 zinc finger cluster four (ZFC4). By combining ZFC4-DNA crystal structure and an in silico docking algorithm, in conjunction with cell viability assays, we screened several chemical libraries against a potentially druggable binding pocket, leading to the discovery of SH6, a compound that selectively targets SALL4-expressing cancer cells. Mechanistic studies revealed that SH6 degrades SALL4 protein through the CUL4A/CRBN pathway, while deletion of ZFC4 abolished this activity. Moreover, SH6 treatment led to a significant 87% tumor growth inhibition of SALL4+ patient-derived xenografts and demonstrated good bioavailability in pharmacokinetic studies. In summary, these studies represent a new approach for IMiD independent drug discovery targeting C2H2 transcription factors such as SALL4 in cancer. Synopsis This study presents a first-in-class small molecule that selectively targets SALL4-expressing cancers. This IMiD-independent strategy leverages a newly identified druggable pocket in SALL4’s ZFC4 domain, which is present in both SALL4A and SALL4B variants. SH6 targets SALL4 via a novel ZFC4 pocket. Degrading SALL4A alone by IMiDs does not cause cancer cell death. Degrading both SALL4A and SALL4B by SH6 leads to apoptosis. The IMiD-independent approach enables new C2H2 TF therapies. This study presents a first-in-class small molecule that selectively targets SALL4-expressing cancers. This IMiD-independent strategy leverages a newly identified druggable pocket in SALL4’s ZFC4 domain, which is present in both SALL4A and SALL4B variants.
Styryl Quinazolinones as Potential Inducers of Myeloid Differentiation via Upregulation of C/EBPα
The CCAAT enhancer-binding protein α (C/EBPα) plays an important role in myeloid cell differentiation and in the enhancement of C/EBPα expression/activity, which can lead to granulocytic differentiation in acute myeloid leukemia (AML) cells. We found that styryl quinazolinones induce upregulation of C/EBPα expression, and thereby induce myeloid differentiation in human myeloid leukemia cell lines. We screened a series of active styryl quinazolinones and evaluated the structure–activity relationship (SAR) of these small molecules in inducing C/EBPα expression—thereby prompting the leukemic cells to differentiate. We observed that compound 78 causes differentiation at 3 μM concentration, while 1 induces differentiation at 10 μM concentration. We also observed an increase in the expression of neutrophil differentiation marker CD11b upon treatment with 78. Both the C/EBPα and C/EBPε levels were found to be upregulated by treatment with 78. These SAR findings are inspiration to develop further modified styryl quinazolinones, in the path of this novel differentiation therapy, which can contribute to the care of patients with AML.
Targeting cancer addiction for SALL4 by shifting its transcriptome with a pharmacologic peptide
Sal-like 4 (SALL4) is a nuclear factor central to the maintenance of stem cell pluripotency and is a key component in hepatocellular carcinoma, a malignancy with no effective treatment. In cancer cells, SALL4 associates with nucleosome remodeling deacetylase (NuRD) to silence tumor-suppressor genes, such as PTEN. Here, we determined the crystal structure of an amino-terminal peptide of SALL4 (1–12) complexed to RBBp4, the chaperone subunit of NuRD, at 2.7 Å, and subsequent design of a potent therapeutic SALL4 peptide (FFW) capable of antagonizing the SALL4–NURD interaction using systematic truncation and amino acid substitution studies. FFW peptide disruption of the SALL4–NuRD complex resulted in unidirectional up-regulation of transcripts, turning SALL4 from a dual transcription repressor-activator mode to singular transcription activator mode. We demonstrate that FFW has a target affinity of 23 nM, and displays significant antitumor effects, inhibiting tumor growth by 85% in xenograft mouse models. Using transcriptome and survival analysis, we discovered that the peptide inhibits the transcription-repressor function of SALL4 and causes massive up-regulation of transcripts that are beneficial to patient survival. This study supports the SALL4–NuRD complex as a drug target and FFW as a viable drug candidate, showcasing an effective strategy to accurately target oncogenes previously considered undruggable.
Targeting transcription factors through an IMiD independent zinc finger domain
Immunomodulatory imide drugs (IMiDs) degrade specific C2H2 zinc finger degrons in transcription factors, making them effective against certain cancers. SALL4, a cancer driver, contains seven C2H2 zinc fingers in four clusters, including an IMiD degron in zinc finger cluster two (ZFC2). Surprisingly, IMiDs do not inhibit growth of SALL4 expressing cancer cells. To overcome this limit, we focused on a non-IMiD degron, SALL4 zinc finger cluster four (ZFC4). By combining AlphaFold and the ZFC4-DNA crystal structure, we identified a potential ZFC4 drug pocket. Utilizing an docking algorithm and cell viability assays, we screened chemical libraries and discovered SH6, which selectively targets SALL4-expressing cancer cells. Mechanistic studies revealed that SH6 degrades SALL4 protein through the CUL4A/CRBN pathway, while deletion of ZFC4 abolished this activity. Moreover, SH6 led to significant 62% tumor growth inhibition of SALL4+ xenografts in vivo and demonstrated good bioavailability in pharmacokinetic studies. In summary, these studies represent a new approach for IMiD independent drug discovery targeting C2H2 transcription factors in cancer.
SALL4B, not targeted by IMiD, is important for SALL4-mediated tumorigenesis
Oncofetal transcription factor SALL4 is essential for cancer cell survival. 1-5 Recently, several groups reported that immunomodulatory imide drugs (IMiDs) could degrade SALL4 in a proteasome-dependent manner. 6,7 Intriguingly, we observed that IMiDs had no effect on SALL4-positive cancer cells. Further studies demonstrated that IMiDs could only degrade SALL4A, one of the SALL4 isoforms. This finding raises the possibility that SALL4B, the isoform not affected by IMiDs, may be essential for SALL4-mediated cancer cell survival. SALL4B knockdown led to an increase in apoptosis and inhibition of cancer cell growth. SALL4B gain-of-function alone led to liver tumor formation in mice. Our observation that protein degraders can possess isoform-specific effects exemplifies the importance of delineating drug action and oncogenesis at the isoform level to develop more effective cancer therapeutics.Oncofetal transcription factor SALL4 is essential for cancer cell survival. 1-5 Recently, several groups reported that immunomodulatory imide drugs (IMiDs) could degrade SALL4 in a proteasome-dependent manner. 6,7 Intriguingly, we observed that IMiDs had no effect on SALL4-positive cancer cells. Further studies demonstrated that IMiDs could only degrade SALL4A, one of the SALL4 isoforms. This finding raises the possibility that SALL4B, the isoform not affected by IMiDs, may be essential for SALL4-mediated cancer cell survival. SALL4B knockdown led to an increase in apoptosis and inhibition of cancer cell growth. SALL4B gain-of-function alone led to liver tumor formation in mice. Our observation that protein degraders can possess isoform-specific effects exemplifies the importance of delineating drug action and oncogenesis at the isoform level to develop more effective cancer therapeutics.
Clinical spectrum of non-alcoholic fatty liver disease in patients with diabetes mellitus
Non-alcoholic fatty liver disease (NAFLD) is increasingly widespread with an overall global estimated prevalence of 25%. Type 2 diabetes Mellitus (T2DM) is a key contributor to NAFLD progression and predicts moderate-severe liver fibrosis and mortality. However, there is currently no uniform consensus on routine NAFLD screening among T2DM patients, and the risk factors of NAFLD and advanced fibrosis among T2DM patients remain to be clarified fully. We explored the prevalence, clinical spectrum, and risk factors of NAFLD and liver fibrosis among T2DM patients. This is a cross-sectional study that enrolled subjects from a primary care clinic and a diabetes centre in Singapore. Subjects aged 21 to 70 years of all ethnic groups with an established T2DM diagnosis were included. Subjects with chronic liver diseases of other aetiologies were excluded. All subjects underwent transient elastography for hepatic steatosis and fibrosis assessment. Their demographics, anthropometric measurements and clinical parameters were collected. Statistical analysis was performed using STATA/SE16.0 software. Among 449 enrolled T2DM subjects, 436 with complete data and valid transient elastography results were analysed. Overall, 78.72% (344/436) of the T2DM subjects had NAFLD, of which 13.08% (45/344) had increased liver stiffness. Higher ALT level (OR = 1.08; 95% CI: 1.03-1.14; p = 0.004), obesity (BMI [greater than or equal to] 27.5 kg/m2, OR = 2.64; 95% CI: 1.28-5.44; p = 0.008) and metabolic syndrome (OR = 4.36; 95% CI 1.40-13.58; p = 0.011) were independent factors associated with increased CAP (NAFLD). Higher AST level (OR = 1.06; 95% CI: 1.02-1.11; p = 0.008), CAP value (OR = 1.02; 95% CI: 1.00-1.03; p = 0.003), lower platelet count (OR = 0.99; 95% CI: 0.98-1.00; p = 0.009) and concomitant hypertension (OR = 4.56; 95% CI: 1.18-17.62; p = 0.028) were independent factors associated with increased liver stiffness. Our study demonstrated a considerably high prevalence of NAFLD among T2DM patients, with the proportion of advanced liver fibrosis among T2DM NAFLD patients much higher than the general population. Given that NAFLD is largely asymptomatic, increased awareness and vigilance for identifying NAFLD and increased liver stiffness among T2DM patients should be advocated.
A Population-Based and Clinical Cohort Validation of the Novel Consensus Definition of Metabolic Hyperferritinemia
Abstract Context There is limited data on the clinical significance of metabolic hyperferritinemia (MHF) based on the most recent consensus. Objective We aimed to validate the clinical outcomes of MHF in the general population and patients with biopsy-proven metabolic dysfunction–associated fatty liver disease (MAFLD). Methods The NHANES database and PERSONS cohort were included. MHF was defined as elevated serum ferritin with metabolic dysfunction (MD) and stratified into different grades according to ferritin (grade 1: 200 [females]/300 [males]—550 ng/mL; grade 2: 550-1000 ng/mL; grade 3: >1000 ng/mL). The clinical outcomes, including all-cause death, comorbidities, and liver histology, were compared between non-MHF and MHF in adjusted models. Results In NHANES, compared with non-MHF with MD, MHF was related to higher risks of advanced fibrosis (P = .036), elevated albumin–creatinine ratio (UACR, P = .001), and sarcopenia (P = .013). Although the association between all grades of MHF and mortality was insignificant (P = .122), grades 2/3 was associated with increased mortality (P = .029). When comparing with non-MHF without MD, the harmful effects of MHF were more significant in mortality (P < .001), elevated UACR (P < .001), cardiovascular disease (P = .028), and sarcopenia (P < .001). In the PERSONS cohort, MHF was associated with more advanced grades of steatosis (P < .001), lobular inflammation (P < .001), advanced fibrosis (P = .017), and more severe hepatocellular iron deposition (P < .001). Conclusion Both in the general population and in at-risk individuals with MAFLD, MHF was related with poorer clinical outcomes.
Gene Delivery by Subconjunctival Injection of Adenovirus in Rats: A Study of Local Distribution, Transgene Duration and Safety
Subconjunctival injection is a minimally invasive route for gene delivery to ocular tissues, but has traditionally been limited to use in the cornea. The accurate ocular distribution of virus has not, however, been previously investigated. Adenovirus is an attractive gene vector as it can deliver large genes and allow for short-term gene expression, but how safe it is when delivered via subconjunctival injection remains to be established. We have characterized the bio-distribution and safety of subconjunctivally administered adenovirus in Brown Norway rats. The bio-distribution and transgene duration of adenovirus carrying luciferase gene (Ad-Luci) at various time intervals were evaluated via bioluminescence imaging after subconjunctival injection. Adenovirus carrying a reporter gene, β-galactosidase (Ad-LacZ) or hrGFP (Ad-hrGFP) was administered subconjunctivally and the viral distribution in various ocular tissues was assessed by histological analysis and quantitative PCR (qPCR). Hepatic damage was assessed by biochemical and immunohistological analysis with TUNEL stain. Systemic immunogenicity was assessed by measuring serum level of TNF-α via ELISA, 2 hours and 14 days after administration of adenovirus. Retinal function was examined by electroretinography. Subconjunctival injection of Ad-Luci induced luciferase expression in the injected eyes within 24 hours, for at least 64 days. Histological analysis showed adenovirus distributed across anterior and posterior ocular tissues. qPCR demonstrated different amounts of adenovirus in different ocular tissues, with the highest amounts closest to the injection site Unlike the intravenous route, subconjunctivally delivered adenovirus did not elicit any detectable hepatic injury or systemic immunogenicity. Retinal function was unaffected by adenovirus irrespective of administration route. In conclusion, an adenoviral vector administered subconjunctivally can infiltrate into different ocular tissues and lead to short-term ocular transgene expression, without causing hepatic injury and immune activation. Therefore, subconjunctivally administered adenovirus may be a promising gene delivery approach for managing anterior and posterior segment eye diseases requiring short-term therapy.
Immune-modulatory genomic properties differentiate gut microbiota of infants with and without eczema
Gut microbiota play an important role in human immunological processes, potentially affecting allergic diseases such as eczema. The diversity and structure of gut microbiota in infants with eczema have been previously documented. This study aims to evaluate by comparative metagenomics differences in genetic content in gut microbiota of infants with eczema and their matched controls. Stools were collected at the age of one month old from twelve infants from an at risk birth cohort in a case control manner. Clinical follow up for atopic outcomes were carried out at the age of 12 and 24 months. Microbial genomic DNA were extracted from stool samples and used for shotgun sequencing. Comparative metagenomic analysis showed that immune-regulatory TCAAGCTTGA motifs were significantly enriched in the six healthy controls (C) communities compared to the six eczema subjects (E), with many encoded by Bifidobacterium (38% of the total motifs in the C communities). Draft genomes of five Bifidobacterium species populations (B. longum, B. bifidum, B. breve, B. dentium, and B. pseudocatenulatum) were recovered from metagenomic datasets. The B. longum BFN-121-2 genome encoded more TCAAGCTTGA motifs (4.2 copies per one million genome sequence) than other Bifidobacterium genomes. Additionally, the communities in the stool of controls (C) were also significantly enriched in functions associated with tetrapyrrole biosynthesis compared to those of eczema (E). Our results show distinct immune-modulatory genomic properties of gut microbiota in infants associated with eczema and provide new insights into potential role of gut microbiota in affecting human immune homeostasis.
Integrated image-based deep learning and language models for primary diabetes care
Primary diabetes care and diabetic retinopathy (DR) screening persist as major public health challenges due to a shortage of trained primary care physicians (PCPs), particularly in low-resource settings. Here, to bridge the gaps, we developed an integrated image–language system (DeepDR-LLM), combining a large language model (LLM module) and image-based deep learning (DeepDR-Transformer), to provide individualized diabetes management recommendations to PCPs. In a retrospective evaluation, the LLM module demonstrated comparable performance to PCPs and endocrinology residents when tested in English and outperformed PCPs and had comparable performance to endocrinology residents in Chinese. For identifying referable DR, the average PCP’s accuracy was 81.0% unassisted and 92.3% assisted by DeepDR-Transformer. Furthermore, we performed a single-center real-world prospective study, deploying DeepDR-LLM. We compared diabetes management adherence of patients under the unassisted PCP arm ( n  = 397) with those under the PCP+DeepDR-LLM arm ( n  = 372). Patients with newly diagnosed diabetes in the PCP+DeepDR-LLM arm showed better self-management behaviors throughout follow-up ( P  < 0.05). For patients with referral DR, those in the PCP+DeepDR-LLM arm were more likely to adhere to DR referrals ( P  < 0.01). Additionally, DeepDR-LLM deployment improved the quality and empathy level of management recommendations. Given its multifaceted performance, DeepDR-LLM holds promise as a digital solution for enhancing primary diabetes care and DR screening. Tailored to provide diabetes management recommendations from large training and validation datasets, an artificial intelligence system integrating language and computer vision capabilities is shown to improve self-management of patients in a prospective implementation study.