Redox Control of Protein Arginine Methyltransferase 1 (PRMT1) Activity.

Elevated levels of asymmetric dimethylarginine (ADMA) correlate with risk factors for cardiovascular disease. ADMA is generated by the catabolism of proteins methylated on arginine residues by protein arginine methyltransferases (PRMTs) and is degraded by dimethylarginine dimethylaminohydrolase. Reports have shown that dimethylarginine dimethylaminohydrolase activity is down-regulated and PRMT1 protein expression is up-regulated under oxidative stress conditions, leading many to conclude that ADMA accumulation occurs via increased synthesis by PRMTs and decreased degradation. However, we now report that the methyltransferase activity of PRMT1, the major PRMT isoform in humans, is impaired under oxidative conditions. Oxidized PRMT1 displays decreased activity, which can be rescued by reduction. This oxidation event involves one or more cysteine residues that become oxidized to sulfenic acid (-SOH). We demonstrate a hydrogen peroxide concentration-dependent inhibition of PRMT1 activity that is readily reversed under physiological H2O2 concentrations. Our results challenge the unilateral view that increased PRMT1 expression necessarily results in increased ADMA synthesis and demonstrate that enzymatic activity can be regulated in a redox-sensitive manner.

A remodeled protein arginine methyltransferase 1 (PRMT1) generates symmetric dimethylarginine.

Protein arginine methylation is emerging as a significant post-translational modification involved in various cell processes and human diseases. As the major arginine methylation enzyme, protein arginine methyltransferase 1 (PRMT1) strictly generates monomethylarginine and asymmetric dimethylarginine (ADMA), but not symmetric dimethylarginine (SDMA). The two types of dimethylarginines can lead to distinct biological outputs, as highlighted in the PRMT-dependent epigenetic control of transcription. However, it remains unclear how PRMT1 product specificity is regulated. We discovered that a single amino acid mutation (Met-48 to Phe) in the PRMT1 active site enables PRMT1 to generate both ADMA and SDMA. Due to the limited amount of SDMA formed, we carried out quantum mechanical calculations to determine the free energies of activation of ADMA and SDMA synthesis. Our results indicate that the higher energy barrier of SDMA formation (ΔΔG(‡) = 3.2 kcal/mol as compared with ADMA) may explain the small amount of SDMA generated by M48F-PRMT1. Our study reveals unique energetic challenges for SDMA-forming methyltransferases and highlights the exquisite control of product formation by active site residues in the PRMTs.

Substrate-induced control of product formation by protein arginine methyltransferase 1.

Protein arginine methyltransferases (PRMTs) aid in the regulation of many biological processes. Accurate control of PRMT activity includes recognition of specific arginyl groups within targeted proteins and the generation of the correct level of methylation, none of which are fully understood. The predominant PRMT in vivo, PRMT1, has wide substrate specificity and is capable of both mono- and dimethylation, which can induce distinct biological outputs. What regulates the specific methylation pattern of PRMT1 in vivo is unclear. We report that PRMT1 methylates a multisite peptide substrate in a nonstochastic manner, with less C-terminal preference, consistent with the methylation patterns observed in vivo. With a single targeted arginine, PRMT1 catalyzed the dimethylation in a semiprocessive manner. The degree of processivity is regulated by substrate sequences. Our results identify a novel substrate-induced mechanism for modulating PRMT1 product specificity. Considering the numerous physiological PRMT1 substrates, as well as the distinct biological outputs of mono- and dimethylation products, such fine-tuned regulation would significantly contribute to the accurate product specificity of PRMT1 in vivo and the proper transmission of biochemical information.

Red blood cell alloimmunizations in thalassaemia patients with regular transfusion in China: A systematic review and meta-analysis.

OBJECTIVE: The development of red blood cell alloimmunization intensifies transfusion complication in thalassaemia patients. The purpose of this paper is to evaluate the existing evidence on the prevalence of erythrocyte alloimmunization in China by meta-analysis. We systematically searched cross-sectional studies regarding the alloimmunization of thalassaemia patients with regular blood transfusion in China from year 2000 to May 2021 in the Cochrane library, PubMed, EMBASE, Web of Science, and Chinese databases including CNKI, Wanfang Data, Vip and CBM. Data extraction and quality evaluation of the included studies were performed. Meta-analysis was performed using the DerSimonian and Laird random-effects models with inverse variance weighting. The presence of publication bias was tested by Egger's test, and the methodological quality of each included article was evaluated by the criteria specific to prevalence studies. RESULTS: A total of 1874 patients and 263 alloantibodies from 11 studies were identified and included in the meta-analysis. The proportion of alloantibodies against antigens belonging to the Rh, MNSs and Kidd systems were as high as 70.3%, 17.9%, and 6.5%, respectively. Meta-analysis showed that the overall prevalence of alloimmunization among transfusion-dependent thalassaemia patients in China is 11.4% (95%CI: 7.2%∼16.3%). CONCLUSIONS: The characteristics of red blood cell alloimmunization among thalassaemia patients with regular transfusion in China differ greatly from those in other countries. Therefore, transfusion strategies shall be actively adapted in line with thalassaemia patients in China to minimize the risk of alloimmunization.

Investigation of the molecular origins of protein-arginine methyltransferase I (PRMT1) product specificity reveals a role for two conserved methionine residues.

Protein-arginine methyltransferases aid in the regulation of many biological processes by methylating specific arginyl groups within targeted proteins. The varied nature of the response to methylation is due in part to the diverse product specificity displayed by the protein-arginine methyltransferases. In addition to site location within a protein, biological response is also determined by the degree (mono-/dimethylation) and type of arginine dimethylation (asymmetric/symmetric). Here, we have identified two strictly conserved methionine residues in the PRMT1 active site that are not only important for activity but also control substrate specificity. Mutation of Met-155 or Met-48 results in a loss in activity and a change in distribution of mono- and dimethylated products. The altered substrate specificity of M155A and M48L mutants is also evidenced by automethylation. Investigation into the mechanistic basis of altered substrate recognition led us to consider each methyl transfer step separately. Single turnover experiments reveal that the rate of transfer of the second methyl group is much slower than transfer of the first methyl group in M48L, especially for arginine residues located in the center of the peptide substrate where turnover of the monomethylated species is negligible. Thus, altered product specificity in M48L originates from the differential effect of the mutation on the two rates. Characterization of the two active-site methionines provides the first insight into how the PRMT1 active site is engineered to control product specificity.

Repositioning Fenofibrate to Reactivate p53 and Reprogram the Tumor-Immune Microenvironment in HPV+ Head and Neck Squamous Cell Carcinoma.

Human papillomavirus-associated head and neck squamous cell carcinoma (HPV+ HNSCC) is recognized as a distinct disease with unique etiology and clinical features. Current standard of care therapeutic modalities are identical for HPV+ and HPV- HNSCC and thus, there remains an opportunity to develop innovative pharmacologic approaches to exploit the inherent vulnerabilities of HPV+ HNSCC. In this study, using an inducible HPVE6E7 knockdown system, we found that HPV+ HNSCC cells are addicted to HPVE6E7, such that loss of these viral oncogenes impaired tumorigenicity in vitro and in vivo. A number of druggable pathways, including PPAR and Wnt, were modulated in response to HPVE6E7 loss. Fenofibrate showed significant anti-proliferative effects in a panel of HPV+ cancer cell lines. Additionally, fenofibrate impaired tumor growth as monotherapy and potentiated the activity of cisplatin in a pre-clinical HPV+ animal model. Systemic fenofibrate treatment induced p53 protein accumulation, and surprisingly, re-programmed the tumor-immune microenvironment to drive immune cell infiltration. Since fenofibrate is FDA-approved with a favorable long-term safety record, repositioning of this drug, as a single agent or in combination with cisplatin or checkpoint blockade, for the HPV+ HNSCC setting should be prioritized.

Treatment failure patterns are similar between p16- and p16+ oropharyngeal squamous cell carcinomas.

Background: The incidence of p16+ oropharyngeal squamous cell carcinoma (OPSCC) has been increasing. The notion that p16+ OPSCC has a propensity for atypical and disseminating metastasis has gained traction. We compared treatment failure patterns in p16+ and p16- OPSCC and evaluated survival impact. Methods: Retrospective analysis of patients with recurrent/metastatic OPSCC disease between 1/2009 and 12/2019. Results: Thirty-eight p16+ and 36 p16- patients were identified. Three distinct failure patterns (distant vs. locoregional, atypical vs. typical, and disseminating vs. non-disseminating) were studied. No significant differences were found between p16+ and p16- patients. Multivariate analysis showed p16 status was an independent prognostic biomarker; p16+ patients have a favorable overall survival compared to p16- patients (HR 0.34, 95% CI 0.16-0.77; P = .005). Conclusions: We challenge the view that p16+ OPSCC exhibits a distinctive treatment failure pattern and showed that p16 status impacts patient survival independent of disease progression.

Plasma cell marker, immunoglobulin J polypeptide, predicts early disease-specific mortality in HPV+ HNSCC.

BACKGROUND: Patients with human papillomavirus (HPV+) head and neck squamous cell carcinoma (HNSCC) have superior prognoses compared with patients with HPV- HNSCC and strategies for treatment de-escalation are under investigation for the HPV+ setting. However, the survival advantage associated with HPV is not universal, and a subset of patients with HPV+ HNSCC fail definitive treatment and progress with metastatic/recurrent disease. Currently, no biomarker is available to distinguish aggressive from indolent HPV+ HNSCC. Immune dysfunction facilitates tumorigenesis and is associated with poor treatment response; therefore, we hypothesized that diminished intratumoral immune cell functionality may be attractive biomarkers to identify patients with HPV+ HNSCC at risk for early disease-specific mortality. METHODS: This is a retrospective analysis of The Cancer Genome Atlas (TCGA) HPV+ HNSCC cohort. RESULTS: Immunoglobulin J polypeptide (IGJ), uniquely expressed in plasma cells, showed a broad expression range in HPV+ HNSCC. Cox regression model, adjusting for clinical covariates, indicated that IGJ is an independent prognostic biomarker for disease-specific survival (DSS) and overall survival (OS). Patients with low IGJ had a 7.2-fold (p<0.001) increase in risk of disease-specific death with a median DSS of 13 months. Low IGJ showed an area under curve (AUC) of 0.89 with 91.0% sensitivity and 87.6% specificity to identify early disease-specific mortality (defined as DSS ≤12 months). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed a global dampening of immune pathways in low IGJ tumors. CONCLUSIONS: Our work showed that IGJ is a robust and independent prognostic biomarker for disease-specific mortality in HPV+ HNSCC. Patient with HPV+ HNSCC with limited adaptive immune functionality should not be candidates for treatment de-escalation modalities.

Impact of p16 Status and Anatomical Site in Anti-PD-1 Immunotherapy-Treated Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma Patients.

In head and neck squamous cell carcinoma (HNSCC), anti-PD-1 inhibitors are approved for recurrent/metastatic (R/M) disease and anticipated to expand to other indications. The impact of p16 status and anatomical site on overall survival (OS) in immunotherapy-treated HNSCC patients remains unresolved. We performed a retrospective analysis of R/M HNSCC patients receiving anti-PD-1 immunotherapy at our academic medical center with an extensive community satellite network. Fifty-three R/M HNSCC patients were treated with anti-PD-1 immunotherapy and had a median OS of 6 months. Anatomical site was associated with distinct OS; oropharynx and larynx patients have superior OS compared to oral cavity patients. Analysis of the OPSCC subset showed p16+ status as a favorable, independent prognostic biomarker (HR 7.67 (1.23-47.8); p = 0.029). Further studies to assess the link between anatomical site, p16 status, and anti-PD-1 treatment outcomes in large cohorts of R/M HNSCC patients managed in real-world clinical practices and clinical trials should be prioritized.

HPV33+ HNSCC is associated with poor prognosis and has unique genomic and immunologic landscapes.

OBJECTIVE: To determine the influence of high-risk HPV genotype on outcomes in HNSCC patients. MATERIALS AND METHODS: This is a retrospective analysis of The Cancer Genome Atlas HNSCC cohort. RESULTS: Using multivariate Cox regression analysis, we revealed that HPV33+ HNSCC patients have inferior overall survival compared to HPV16+ HNSCC patients independent of anatomical site (HR 3.59, 95% CI 1.58-8.12; p = 0.002). A host anti-viral immune response, apolipoprotein B mRNA editing enzyme, and catalytic polypeptide-like mutational signature, was under represented and, aneuploidy and 3p loss were more frequent in HPV33+ tumors. A deconvolution RNA-Seq algorithm to infer immune cell fractions revealed that CD8+ cytotoxic T-cell infiltration was reduced in HPV33+ compared to HPV16+ tumors (1.3% vs. 2.7%, p = 0.007). TGFB1, a negative modulator of T-cell infiltration and function, showed expression and pathway enrichment in HPV33+ tumors. CONCLUSIONS: Our work reveals that HPV genotype, in particular HPV33, has a powerful impact on HNSCC patient survival. We argue that p16 immunohistochemistry as a surrogate biomarker for HPV+ status will lead to sub-optimal risk stratification and advocate HPV genotype testing as standard of care.

p53 functional states are associated with distinct aldehyde dehydrogenase transcriptomic signatures.

p53 and aldehyde dehydrogenase (ALDH) have been implicated in key tumorigenesis processes including cancer initiating cell (CIC) maintenance; however, the relationship between these two mediators remains poorly defined. In this study, ALDH isoform expression diversity was revealed in CICs with disparate p53 functional states: gain of function, high risk p53 mutation (p53HRmut) and wildtype p53 (p53WT) inactivated by the human papillomavirus 16 (HPV16) E6 oncogene. Interrogation of head and neck squamous cell carcinoma (HNSCC) cell lines and patient tumors showed that HPV16+/p53WT cases have higher ALDH variance score (AVS), a measure of tumor ALDH isoform expression diversity, compared to HPV-/p53HRmut cases (p = 0.03). AVS and several individual ALDH isoforms were associated with prognosis in HPV16+/p53WT HNSCC but not in HPV-/p53HRmut HNSCC. Knockdown of the dominant ALDH isoform in high AVS HNSCC depleted the CIC pool in vitro and in vivo. Our results demonstrate that p53 functional states are associated with distinct ALDH isoform transcriptomic signatures. Moreover, tumor ALDH profiling may provide insight on which ALDH isoform to target in high AVS HNSCC tumors to deplete the CIC population.

Human papillomavirus insertions identify the PIM family of serine/threonine kinases as targetable driver genes in head and neck squamous cell carcinoma.

Human papillomavirus (HPV) insertions in cancer genomes have been linked to various forms of focal genomic instability and altered expression of neighboring genes. Here we tested the hypothesis that investigation of HPV insertions in a head and neck cancer squamous cell carcinoma (HNSCC) cell line would identify targetable driver genes contributing to oncogenesis of other HNSCC. In the cell line UPCI:SCC090 HPV16 integration amplified the PIM1 serine/threonine kinase gene ~16-fold, thereby increasing transcript and protein levels. We used genetic and pharmacological approaches to inhibit PIM kinases in this and other HNSCC cell lines. Knockdown of PIM1 transcripts by transfected short hairpin RNAs reduced UPCI:SCC090 viability. CRISPR/Cas9-mediated mutagenesis of PIM1 caused cell cycle arrest and apoptosis. Pharmacological inhibition of PIM family kinases decreased growth of UPCI:SCC090 and additional HNSCC cell lines in vitro and a xenograft UPCI:SCC090 model in vivo. Based on established interactions between intracellular signaling pathways and relatively high levels of gene expression in almost all HNSCC, we also evaluated combinations of PIM kinase and epidermal growth factor receptor (EGFR) inhibitors. Dual inhibition of these pathways resulted in supra-additive cell death. These data support clinical testing of PIM inhibitors alone or in combination in HNSCC.

Synthesis, crystal structure and antimicrobial activity of deoxybenzoin derivatives from genistein.

A series of deoxybenzoin derivatives from genistein were synthesized and their structures were elucidated by (1)H NMR, mass spectral data and micro analyses. The structures of 2, 7 and 10 were determined by single-crystal X-ray analysis. These obtained compounds were evaluated for their assayed antibacterial (Bacillus subtilis, Escherichia coli, Pseudomonas fluorescence and Staphylococcus aureus) and antifungal (Aspergillus niger, Candida albicans and Trichophyton rubrum) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) method. Most compounds have displayed comparable antibacterial activity against bacterial. On the basis of the biological results, structure-activity relationships are discussed.