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The brain is a common target organ for breast cancer metastasis, and the risk of brain metastasis is usually high for patients with HER2-positive breast cancer. While T-DXd showed positive results in HER2-positive breast cancer brain metastasis (BCBM), its activity and blood-brain barrier (BBB) permeability in active BCBM need to be further validated (TUXEDO-1 included 15 patients with active brain metastasis). Tucatinib plus Trastuzumab and Capecitabine triplet showed efficacy in patients with brain metastasis, but Tucatinib alone has poor BBB penetration. There is still an unmet medical need for active HER2-positive BCBM. VRN101099 is a highly selective kinase inhibitor of HER2 (Eurofins scanMAX Kinase Profiling, S-score (35) of 0.01). VRN101099 has single- to double-digit nanomolar (IC50) cellular potency in HER2-dependent cancer cells, and Ba/F3 cells expressing HER2 wild type or mutations with selectivity over wildtype EGFR. VRN101099 inhibited proliferation of BT474 with 3.6 nM IC50 but HaCaT with 829.2 nM IC50. VRN101099 binds HER2 kinase by forming a covalent bond to the Cys805 and its irreversible inhibition resulted in a longer target resident time than Tucatinib, confirmed by in vitro washout experiments. Robust in vivo activity of VRN101099 was observed in HER2-positive BT474 xenograft models. Moreover, once daily oral administration of VRN101099 significantly regressed intracranial BT474 tumor, demonstrating greater efficacy than twice daily oral administration of Tucatinib. These results were well explained by the superior brain to plasma exposure of VRN101099 to Tucatinib. Also, VRN101099 showed high exposure in the target organ, the fat pad, which potentiated better clinical translation. These anti-tumor efficacies are correlated with pharmacodynamic responses, as confirmed by decreased HER2, AKT, and ERK phosphorylation. In summary, VRN101099 is a brain penetrant, orally bioavailable, irreversible, and highly selective inhibitor of HER2 with therapeutic potential in HER2-positive BCBM. These data support the clinical development of VRN101099 in HER2-driven cancers. Citation Format: Yikyung Ko, Jihye yoo, Hong-ryul Jung, Hyerim Lim, YeongDeok Lee, Se Hyuk Kim, Dong Guk Shin, Serin Cho, Myung hoe Heo, Haelee Kim, Ha Yeon Cho, Ah Reum Han, Eunhwa Ko, Hwan Geun Choi, Deakwon Kim, Sunghwan Kim. VRN101099, Brain Permeable HER2 Kinase Inhibitor, Shows the Anti-tumor Activity in Preclinical Models of HER2-positive Cancers [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-11-03.

Breast cancer (BC) is the second most common cancer associated with brain metastasis (BM) and among patients with breast cancer brain metastasis (BCBM), human epidermal growth factor receptor 2 (HER2)-positive breast cancer is most likely to develop BM. The overall prognosis of HER2-positive BCBM remains dismal with median survival time after BM of less than a year. Drugs like T-DM1, T-DXd and Tucatinib are reported to deliver a progression-free survival benefit in HER2-positive BCBM patients, but there are still unmet needs for a drug that crosses the blood brain barrier more effectively. We develop VRN101396, a brain penetrant, orally available, and irreversible small molecule inhibitor targeting HER2 to offer a new therapeutic option for the treatment of HER2-positive BCBM. VRN101396 potently inhibits catalytic activity of HER2 but spares wild-type EGFR. In HER2-positive breast cancer cell lines BT474 and SK-BR3 and gastric cancer cell line NCI-N87, VRN101396 inhibited the cell proliferation and phosphorylation of HER2 with single- or double-digit nanomolar IC50 values while inhibiting wild type EGFR with an IC50 value of >100 nM. In both subcutaneous and intracranial efficacy mouse models, once-daily oral dose of VRN101396 significantly inhibited tumor growth and achieved tumor regression. In N87 subcutaneous xenograft model, VRN101396 alone showed superior efficacy to the combination of Tucatinib and Trastuzumab. Additionally, in intracranial xenograft model, VRN101396 showed superior efficacy to Tucatinib. Pharmacokinetics of VRN101396 displayed higher brain exposure than tucatinib and lapatinib, indicating better target engagement in the brain. Pharmacodynamic analysis revealed that VRN101396 reduced phosphorylation of HER2, HER3, AKT, and ERK compared to vehicle group after administration up to 24 hours. In conclusion, VRN101396 is a therapeutic candidate for the treatment of HER2-positive BC, BCBM and gastric cancer. Citation Format: Hong-ryul Jung, Sunghwan Kim, Jihye Yoo, Chan mi Park, Somi Lee, Hyoju Lee, Youngyi Lee, Jinhee Park, Kyungah Seo, Dong-Hyuk Seo, Eunhwa Ko, Jung Beom Son, Deakwon Kim, Hwan Geun Choi, Nam Doo Kim. VRN101396, a brain-permeable HER2 inhibitor, shows the anti-tumor activity in preclinical HER2-positive cancer models [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-15.

The spastin protein (SPAST) contains an ATPase with diverse cellular activities (AAA) domain and regulates microtubule dynamics. Missense mutations of the SPAST gene are frequently detected in patients with hereditary spastic paraplegias (HSPs) and represent the main reason of loss of SPAST function; however, the pathogenicity of mutant SPAST is heterogeneous. Here, SPAST variant with an I344K mutation (I344K-SPAST) was identified in a Korean family with autosomal dominant-type HSP. We investigated the role of the I344K-SPAST in HSP to provide a therapeutic mechanism. The I344K-SPAST mutation prolonged the half-life of the protein compared to wild-type SPAST (WT-SPAST) in cells by modulating post-translational modifications for proteasomal degradation. I344K-SPAST was localized in microtubule but defective in microtubule severing and ATPase activity compared to WT-SPAST in vitro and in cells. Mutant M87 isoform harboring the same mutation with I344K-M1 SPAST also increased protein stability and loss of MT severing activity, but the pathogenicity was not stronger than I344K-M1 SPAST in neurite outgrowth. Overexpression of I344K-SPAST resulted in microtubule accumulation following inhibited neurite growth in neuroblastoma, neural progenitor cells and mouse primary cortical neurons. Conversely, these pathogenic effects of I344K-SPAST were reduced by overexpression of WT-M1 SPAST in a dose dependent manner since WT-SPAST could interact with I344K-SPAST. Our data therefore provide proof-of-concept that gene transfer of WT-M1 SPAST may serve as a valid therapeutic option for HSPs.

We fabricated a spheroid-forming unit (SFU) for efficient and economic production of cell spheroids. We optimized the protocol for generating large and homogenous liver cancer cell spheroids using Huh7 hepatocellular carcinoma (HCC) cells. The large Huh7 spheroids showed apoptotic and proliferative signals in the centre and at the surface, respectively. In particular, hypoxia-induced factor-1 alpha (HIF-1α) and ERK signal activation were detected in the cell spheroids. To diminish core necrosis and increase the oncogenic character, we co-cultured spheroids with 2% human umbilical vein endothelial cells (HUVECs). HUVECs promoted proliferation and gene expression of HCC-related genes and cancer stem cell markers in the Huh7 spheroidsby activating cytokine signalling, mimicking gene expression in liver cancer. HUVECs induced angiogenesis and vessel maturation in Huh7 spheroids in vivo by activating epithelial–mesenchymal transition and angiogenic pathways. The large Huh7 cell spheroids containing HUVECs survived at higher concentrations of anti-cancer drugs (doxorubicin and sorafenib) than did monolayer cells. Our large cell spheroid provides a useful in vitro HCC model to enable intuitive observation for anti-cancer drug testing.

T cells navigate diverse microenvironments to perform immune responses. Micro-scale topographical structures within the tissues, which may inherently exist in normal tissues or may be formed by inflammation or injury, can influence T cell migration, but how T cell migration is affected by such topographical structures have not been investigated. In this study, we fabricated ramp-like structures with a 5 μm height and various slopes, and observed T cells climbing up the ramp-like structures. T cells encountering the ramp-like structures exhibited MLC accumulation near head-tail junctions contacting the ramp-like structures, and made turns to the direction perpendicular to the ramp-like structures. Pharmacological study revealed that lamellipodia formation mediated by arp2/3 and contractility regulated by myosin light chain kinase (MLCK) were responsible for the intriguing turning behavior of T cells climbing the ramp-like structures. Arp2/3 or MLCK inhibition substantially reduced probability of T cells climbing sharp-edged ramp-like structures, indicating intriguing turning behavior of T cells mediated by lamellipodia formation and MLCK activity may be important for T cells to access inflamed or injured tissues with abrupt topographical changes.

Regulation of intracellular Ca2+ signaling is a major determinant of CD8+ T cell responsiveness, but the mechanisms underlying this regulation of Ca2+ levels, especially in naïve CD8+ T cells, are not fully defined. Here, we showed that microRNA-150 (miR-150) controls intracellular Ca2+ levels in naïve CD8+ T cells required for activation by suppressing TMEM20, a negative regulator of Ca2+ extrusion. miR-150 deficiency increased TMEM20 expression, which resulted in increased intracellular Ca2+ levels in naïve CD8+ T cells. The subsequent increase in Ca2+ levels induced expression of anergy-inducing genes, such as Cbl-b, Egr2, and p27, through activation of NFAT1, as well as reduced cell proliferation, cytokine production, and the antitumor activity of CD8+ T cells upon antigenic stimulation. The anergy-promoting molecular milieu and function induced by miR-150 deficiency were rescued by reinstatement of miR-150. Additionally, knockdown of TMEM20 in miR-150-deficient naïve CD8+ T cells reduced intracellular Ca2+ levels. Our findings revealed that miR-150 play essential roles in controlling intracellular Ca2+ level and activation in naïve CD8+ T cells, which suggest a mechanism to overcome anergy induction by the regulation of intracellular Ca2+ levels.

Regulation of intracellular Ca2+ signaling is a major determinant of CD8+ T cell responsiveness, but the mechanisms underlying this regulation of Ca2+ levels, especially in naïve CD8+ T cells, are not fully defined. Here, we showed that microRNA-150 (miR-150) controls intracellular Ca2+ levels in naïve CD8+ T cells required for activation by suppressing TMEM20, a negative regulator of Ca2+ extrusion. miR-150 deficiency increased TMEM20 expression, which resulted in increased intracellular Ca2+ levels in naïve CD8+ T cells. The subsequent increase in Ca2+ levels induced expression of anergy-inducing genes, such as Cbl-b, Egr2, and p27, through activation of NFAT1, as well as reduced cell proliferation, cytokine production, and the antitumor activity of CD8+ T cells upon antigenic stimulation. The anergy-promoting molecular milieu and function induced by miR-150 deficiency were rescued by reinstatement of miR-150. Additionally, knockdown of TMEM20 in miR-150-deficient naïve CD8+ T cells reduced intracellular Ca2+ levels. Our findings revealed that miR-150 play essential roles in controlling intracellular Ca2+ level and activation in naïve CD8+ T cells, which suggest a mechanism to overcome anergy induction by the regulation of intracellular Ca2+ levels.

Immunological synapse (IS) is a complex supramolecular structure formed at the interface between T cells and antigen presenting cells (APCs) during T cell antigen recognition. Microfabricated platforms have made great contributions to our understanding of the assembly dynamics and functional roles of the T cell synapses over the last decade. Here, we review three different types of microfabricated platforms developed to modulate and monitor the T cell synapse assembly. Firstly, multi-protein micropatterned surfaces presenting key ligands for T cell activation that can modulate the spatial distribution of receptors/signaling molecules in T cell synapses are described. Secondly, micropatterned supported bilayers that can modulate the dynamics of T cell receptor (TCR) microclusters are introduced. Lastly, T-APC pair arrays that allow for improved fluorescence live cell imaging are discussed. WIREs Nanomed Nanobiotechnol 2013, 5:67–74. doi: 10.1002/wnan.1182 For further resources related to this article, please visit the WIREs website.

Similar to stem cells, naive T cells undergo asymmetric division following activation. While asymmetric division of T cells has been shown to be an important mechanism for the generation of lymphocyte fate diversity during immune responses, key factors that influence whether T cells will undergo symmetric or asymmetric divisions are not completely understood. Here, we utilized immunological synapse arrays (ISAs) to begin to dissect mechanisms of asymmetric T lymphocyte division. ISAs are protein micropatterned surfaces composed of two segregated regions, activation sites and adhesion fields. Activation sites are small spots presenting activation signals such as anti-CD3 and anti-CD28, and adhesion fields are the remaining regions surrounding activation sites immobilized with interintercel adhesion molecule 1 (ICAM-1). By varying the size and the distance between the activation sites and measuring the incidence of asymmetric cell divisions, we found that the distance between activation sites is an important regulator of asymmetric division. Further analysis revealed that more symmetric divisions occurred when two nascent daughter cells stably interacted with two distinct activation sites throughout and following cytokinesis. In contrast, more asymmetric divisions occurred when only one daughter cell remained anchored on an activation site while the other daughter became motile and moved away following cytokinesis. Together, these results indicate that TCR signaling events during cytokinesis may repolarize key molecules for asymmetric partitioning, suggesting the possibility that the density of antigen presenting cells that interact with T cells as they undergo cytokinesis may be a critical factor regulating asymmetric division in T cells.

Microscope projection photolithography (MPP) based on a protein-friendly photoresist is a versatile tool for the fabrication of protein- and cell-micropatterned surfaces. Photomasks containing various features can be economically produced by printing features on transparency films. Features in photomasks are projected by the objective lens of a microscope, resulting in a significant reduction of the feature size to as small as ~1 μm, close to the practical limit of light-based microfabrication. A fluorescence microscope used in most biology labs can be used for the fabrication process with some modifications. Using such a microscope, multistep MPP can be readily performed with precise registration of each micropattern on transparency film masks. Here, we describe methods of the synthesis and characterization of a protein-friendly photoresist poly(2,2-dimethoxy nitrobenzyl methacrylate-r-methyl methacrylate-r-poly(ethylene glycol) methacrylate) and the setups of fluorescence microscopes and the MPP procedures. In addition, we describe the protocols used in the micropatterning of multiple lymphocytes and the dynamic micropatterning of adherent cells.

Microscope projection photolithography (MPP) based on a protein-friendly photoresist is a versatile tool for the fabrication of protein- and cell-micropatterned surfaces. Photomasks containing various features can be economically produced by printing features on transparency films. Features in photomasks are projected by the objective lens of a microscope, resulting in a significant reduction of the feature size to as small as ~1 μm, close to the practical limit of light-based microfabrication. A fluorescence microscope used in most biology labs can be used for the fabrication process with some modifications. Using such a microscope, multistep MPP can be readily performed with precise registration of each micropattern on transparency film masks. Here, we describe methods of the synthesis and characterization of a protein-friendly photoresist poly(2,2-dimethoxy nitrobenzyl methacrylate-r-methyl methacrylate-r-poly(ethylene glycol) methacrylate) and the setups of fluorescence microscopes and the MPP procedures. In addition, we describe the protocols used in the micropatterning of multiple lymphocytes and the dynamic micropatterning of adherent cells.

Dynamics of small-sized multicellular clusters is important for many biological processes including embryonic development and cancer metastasis. Previous methods to fabricate multicellular clusters depended on stochastic adhesion and proliferation of cells on defined areas of cell-adhering islands. This made precise control over the number of cells within multicellular clusters impossible. Variation in numbers may have minimal effects on the behavior of multicellular clusters composed of tens of cells but would have profound effects on groups with fewer than ten cells. Herein, we report a new dynamic cell micropatterning method using a cell-friendly photoresist film by multistep microscope projection photolithography. We first fabricated single cell arrays of partially spread cells. Then, by merging neighboring cells, we successfully fabricated multicellular clusters with precisely controlled number, composition, and geometry. Using this method, we generated multicellular clusters of Madin-Darby canine kidney cells with various numbers and initial geometries. Then, we systematically investigated the effect of multicellular cluster sizes and geometries on their motility behaviors. We found that the behavior of small-sized multicellular clusters was not sensitive to initial configurations but instead was determined by dynamic force balances among the cells. Initially, the multicellular clusters exhibited a rounded morphology and minimal translocation, probably due to contractility at the periphery of the clusters. For 2-cell and 4-cell clusters, single leaders emerged over time and entire groups aligned and comigrated as single supercells. Such coherent behavior did not occur in 8-cell clusters, indicating a critical group size led by a single leader may exist. The method developed in the study will be useful for the study of collective migration and multicellular dynamics.

Immunological synapse (IS) is a complex supramolecular structure formed at the interface between T cells and antigen presenting cells (APCs) during T cell antigen recognition. Microfabricated platforms have made great contributions to our understanding of the assembly dynamics and functional roles of the T cell synapses over the last decade. Here, we review three different types of microfabricated platforms developed to modulate and monitor the T cell synapse assembly. Firstly, multi-protein micropatterned surfaces presenting key ligands for T cell activation that can modulate the spatial distribution of receptors/signaling molecules in T cell synapses are described. Secondly, micropatterned supported bilayers that can modulate the dynamics of T cell receptor (TCR) microclusters are introduced. Lastly, T-APC pair arrays that allow for improved fluorescence live cell imaging are discussed.