{"id":848,"date":"2025-05-07T15:13:58","date_gmt":"2025-05-07T15:13:58","guid":{"rendered":"http:\/\/wmtc2006.com\/?p=848"},"modified":"2025-05-07T15:13:58","modified_gmt":"2025-05-07T15:13:58","slug":"results-are-presented-as-a-percentage-of-the-fluorescence-signal-present-at-time-0","status":"publish","type":"post","link":"https:\/\/wmtc2006.com\/?p=848","title":{"rendered":"\ufeffResults are presented as a percentage of the fluorescence signal present at time 0"},"content":{"rendered":"

\ufeffResults are presented as a percentage of the fluorescence signal present at time 0. internalized when bound to Pyrantel pamoate CD33 and, as CD33PAN\/CD3 BsAb, had potent cytolytic effects against CD33+cells. Together, our data provide rationale for further development of CD33PANantibody-based Pyrantel pamoate therapeutics. == INTRODUCTION == CD33 (Siglec-3) is a differentiation antigen that is primarily displayed on maturing and mature myeloid cells and their neoplastic cell counterparts.1,2With this expression pattern, there have been long-standing efforts in therapeutically targeting CD33+cells, first and foremost in acute myeloid leukemia (AML)1,3,4but also CD33+tumor cells in other malignancies, CD33+myeloid-derived suppressor cells, and normal CD33+microglial cells.5In AML, longer survival of some patients treated with the antibody-drug conjugate gemtuzumab ozogamicin (GO) validates CD33 as drug target.6 The success and limitations of GO have fueled ongoing work to develop more effective CD33-directed therapeutics.7However, targeting CD33 has proven difficult, and several drugs failed clinically because of lack of efficacy. 7Efforts have therefore centered around developing more potent anti-CD33 treatment modalities, including T cell engaging bispecific antibodies (BsAbs) and chimeric antigen receptor (CAR)-modified T cells.7As one important limitation of these efforts, existing and investigational therapeutics, including GO, almost exclusively recognize immune-dominant epitope(s) within the exon 2-encoded membrane-distal V-set domain of CD33.7Since membrane-proximal binding of antibodies can increase their effector functions,811we reasoned targeting CD33 with antibodies against the membrane-proximal C2-set domain might optimize CD33-directed therapy that engage immune effector cells. Here, we test this concept experimentally and describe the generation of a series of C2-set domain-directed CD33 antibodies and derived therapeutics. == MATERIALS AND METHODS == == Generation of artificial CD33 proteins and chimeras. == CD33FL[full-length CD33] + CD22 4D was generated using the endogenous CD33 signal peptide (amino acids [aa] 1-17), a 6-histidine tag, 3x glycine linker, the human CD33 extracellular domain (ECD, aa 18-259), a portion of the human CD22 ECD comprising C2-type domains 3-6 (aa 331-683), the CD33 transmembrane domain, and the CD33 intracellular domain (aa 260-364). Codons were optimized for human translation and cDNA synthesized as gBlock (Integrated DNA Technologies, Coralville, Iowa, USA) for cloning into pRRLsin.cPPT.MSCV lentivirus constructs containing an IRES-Enhanced Green Fluorescent Protein (EGFP) cassette. The CD33FL+ CD22 2D construct used CD33FL+ CD22 4D Pyrantel pamoate as template and Gibson assembly to splice out CD22 aa 331-504, removing C2-type domains 3 and 4. A CD33FLconstruct has been described.1215A truncated CD33 construct lacking the exon 3\/4-encoded C2-set domain (CD33E3-4) was engineered using site-directed mutagenesis to splice out CD33 ECD aa 140-232. All lentiviral constructs were confirmed by Sanger sequencing. == Parental and engineered human acute leukemia cell lines. == Human myeloid K562 and MOLM-13 cells were grown in RPMI-1640 medium with 10% fetal bovine serum and penicillin\/streptomycin. Growth conditions for all other cell lines have been described.15Lentivirally-transduced sublines overexpressing various CD33 proteins were generated at multiplicities of infection (MOI) of 0.25-25.1214,16EGFP-positive cells were isolated by FACS and re-cultured for further analysis\/use. All cell lines were routinely tested for mycoplasma contamination (MycoAlert Mycoplasma Detection Kit; Lonza, Basel, Switzerland) and were authenticated using standard STR CODIS typing. == Primary AML patient specimens. == Frozen aliquots of primary AML patient specimens were obtained from an institutional repository under protocols approved by the Fred Hutchinson Cancer Research Center Institutional Review Board and cultured as described.15,17All patients provided written informed consent for the collection and use of their biospecimens for research purposes. == Genetic deletion Rabbit Polyclonal to ADA2L<\/a> of CD33. == Clustered regularly interspaced short palindromic repeat (CRISPR)\/Cas9-editing was carried out by electroporating Pyrantel pamoate purified Cas9 protein (TrueCut Cas9 V2; ThermoFisher Scientific) complexed with synthetic guide RNA (sgRNA) targeting exon 1 of CD33 (sequence 5- CTGCTGCCCCTGCTGTGGGC-3) using the ECM 380 Square Wave Electroporation system (Harvard Pyrantel pamoate<\/a> Apparatus, Cambridge, MA) as described.15,18CD33single cells were isolated via FACS, and genomic DNA from individual clones analyzed by Sanger sequencing to confirm disruption or frame-shift.<\/p>\n","protected":false},"excerpt":{"rendered":"

\ufeffResults are presented as a percentage of the fluorescence signal present at time 0. internalized when bound to Pyrantel pamoate CD33 and, as CD33PAN\/CD3 BsAb, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[46],"tags":[],"class_list":["post-848","post","type-post","status-publish","format-standard","hentry","category-heat-shock-protein-90"],"yoast_head":"\n\ufeffResults are presented as a percentage of the fluorescence signal present at time 0 - Discovery and characterization of Histamine-2 Receptor Antagonists<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/wmtc2006.com\/?p=848\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"\ufeffResults are presented as a percentage of the fluorescence signal present at time 0 - 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