Multiplexable and Scalable Aqueous Synthesis Platform for Oleate-Based, Bilayer-Coated Gold Nanoparticles

Despite gold-based nanomaterials having a unique role in nanomedicine, among other fields, synthesis limitations relating to reaction scale-up and control result in prohibitively high gold nanoparticle costs. In this work, a new preparation procedure for lipid bilayer-coated gold nanoparticles in water is presented, using sodium oleate as reductant and capping agent. The seed-free synthesis not only allows for size precision (8-30 nm) but also remarkable particle concentration (10 mm Au). These reaction efficiencies allow for multiplexing and reaction standardization in 96-well plates using conventional thermocyclers, in addition to simple particle purification via microcentrifugation. Such a multiplexing approach also enables detailed spectroscopic investigation of the nonlinear growth process and dynamic sodium oleate/oleic acid self-assembly. In addition to scalability (at gram-level), resulting gold nanoparticles are stable at physiological pH, in common cell culture media, and are autoclavable. To demonstrate the versatility and applicability of the reported method, a robust ligand exchange with thiolated polyethylene glycol analogues is also presented.

Abstract 1563: Concomitant inhibition of Aurora kinase A and WEE1 kinases results in synergistic tumor control and heightens DNA replication stress in head and neck and lung carcinomas

Human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) and lung cancer mainly harbor disruptive mutations in TP53 and/or CDKN2A tumor suppressor genes, which are associated with refractoriness to treatment as well as poor prognosis and survival. Mutational loss of TP53 function fosters elevated expression of Aurora kinase A (AURKA) that plays a crucial role in mitotic progression at G2/M and stabilizes DNA replication forks at S phase. We have previously demonstrated that combined inhibition of AURKA and WEE1, a G2/M checkpoint kinase induced by replication stress, results in synergistic anti-tumor effects in HNSCC in vitro and in vivo. We have now further confirmed synergy using the highly selective AURKA inhibitor VIC1911 in HNSCC and lung cancers harboring TP53 mutations and explored mechanisms of cell death. VIC1911 and adavosertib combination synergistically suppressed cell growth and survival in both 2D- and 3D-culture systems relative to vehicle or single-agent treatment in TP53-mutated HNSCC FaDu and CAL27, and lung cancer A549 and NCI-H358 cells, with no observable toxicity in normal cells, predicting a favorable therapeutic index. Furthermore, combination treatment accelerated mitotic entry and resulted in accumulation of mitotic catastrophe, as demonstrated by time-lapse imaging, and apoptotic cell death as evidenced by cleaved PARP assays. Notably, we found that combination VIC1911 and adavosertib in HNSCC cells drastically slowed and stalled progression of replication forks in DNA fiber analysis (Mean: DMSO=3.117; adavosertib=1.495; VIC1911=0.9757; combination=0.5548 kb/min; P <0.0001) and amplified DNA damage as measured by γH2AX, indicating induction of severe replication stress. In vivo, this combination resulted in significant tumor regression in both HNSCC and lung adenocarcinoma patient-derived and cancer cell-derived xenografted mice compared with either vehicle or single-agent treatment. Taken together, these results suggest that AURKA inhibition increases dependency on WEE1 by enhancing replication stress and mitotic catastrophe, and support clinical evaluation of combined AURKA and WEE1 inhibition as a novel and effective treatment for HNSCC and lung cancer patients with elevated AURKA expression.

Citation Format: Jong Woo Lee, Sundong Kim, Sebastian Cruz-Gomez, Jackie Shi, Cindy Yang, Barbara Burtness. Concomitant inhibition of Aurora kinase A and WEE1 kinases results in synergistic tumor control and heightens DNA replication stress in head and neck and lung carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1563.

A specialized tyrosine-based endocytosis signal in MR1 controls antigen presentation to MAIT cells

MR1 is a highly conserved microbial immune-detection system in mammals. It captures vitamin B-related metabolite antigens from diverse microbes and presents them at the cell surface to stimulate MR1-restricted lymphocytes including mucosal-associated invariant T (MAIT) cells. MR1 presentation and MAIT cell recognition mediate homeostasis through host defense and tissue repair. The cellular mechanisms regulating MR1 cell surface expression are critical to its function and MAIT cell recognition, yet they are poorly defined. Here, we report that human MR1 is equipped with a tyrosine-based motif in its cytoplasmic domain that mediates low affinity binding with the endocytic adaptor protein 2 (AP2) complex. This interaction controls the kinetics of MR1 internalization from the cell surface and minimizes recycling. We propose MR1 uses AP2 endocytosis to define the duration of antigen presentation to MAIT cells and the detection of a microbial metabolic signature by the immune system.

Endoplasmic reticulum chaperones stabilize ligand-receptive MR1 molecules for efficient presentation of metabolite antigens

The antigen-presenting molecule MR1 (MHC class I-related protein 1) presents metabolite antigens derived from microbial vitamin B2 synthesis to activate mucosal-associated invariant T (MAIT) cells. Key aspects of this evolutionarily conserved pathway remain uncharacterized, including where MR1 acquires ligands and what accessory proteins assist ligand binding. We answer these questions by using a fluorophore-labeled stable MR1 antigen analog, a conformation-specific MR1 mAb, proteomic analysis, and a genome-wide CRISPR/Cas9 library screen. We show that the endoplasmic reticulum (ER) contains a pool of two unliganded MR1 conformers stabilized via interactions with chaperones tapasin and tapasin-related protein. This pool is the primary source of MR1 molecules for the presentation of exogenous metabolite antigens to MAIT cells. Deletion of these chaperones reduces the ER-resident MR1 pool and hampers antigen presentation and MAIT cell activation. The MR1 antigen-presentation pathway thus co-opts ER chaperones to fulfill its unique ability to present exogenous metabolite antigens captured within the ER.

Organ-specific isoform selection of fatty acid–binding proteins in tissue-resident lymphocytes

Tissue-resident memory T (TRM) cells exist throughout the body, where they are poised to mediate local immune responses. Although studies have defined a common mechanism of residency independent of location, there is likely to be a level of specialization that adapts TRM cells to their given tissue of lodgment. It has been shown that TRM cells in the skin rely on the uptake of exogenous fatty acids for their survival and up-regulate fatty acid–binding protein 4 (FABP4) and FABP5 as part of their transcriptional program. However, FABPs exist as a larger family of isoforms, with different members selected in a tissue-specific fashion that is optimized for local fatty acid availability. Here, we show that although TRM cells in a range of tissue widely express FABPs, they are not restricted to FABP4 and FABP5. Instead, TRM cells show varying patterns of isoform usage that are determined by tissue-derived factors. These patterns are malleable because TRM cells relocated to different organs modify their FABP expression in line with their new location. As a consequence, these results argue for tissue-specific overlays to the TRM cell residency program, including FABP expression that is tailored to the particular tissue of TRM cell lodgment.