Empowering pancreatic tumor homing with augmented anti-tumor potency of CXCR2-tethered CAR-NK cells

Chimeric antigen receptor (CAR)-engineered natural killer (NK) cells are a promising immunotherapy for solid cancers; however, their effectiveness against pancreatic cancer is limited by the immunosuppressive tumor microenvironment. In particular, low NK cell infiltration poses a major obstacle that reduces cytotoxicity. The current study aimed to enhance the tumor-homing capacity of CAR-NK cells by targeting the chemokine-chemokine receptor axis between NK and pancreatic cancer cells. To this end, data from a chemokine array and The Cancer Genome Atlas pan-cancer cohort were analyzed. Pancreatic cancer cells were found to secrete high levels of ligands for C-X-C motif receptor 1 (CXCR1) and CXCR2. Subsequently, we generated anti-mesothelin CAR-NK cells incorporating CXCR1 or CXCR2 and evaluated their tumor-killing abilities in 2D cancer cell co-culture and 3D tumor-mimetic organoid models. CAR-NK cells engineered with CXCR2 demonstrated enhanced tumor killing and strong infiltration of tumor sites. Collectively, these findings highlight the potential of CXCR2-augmented CAR-NK cells as a clinically relevant modality for effective pancreatic cancer treatment. By improving their infiltration and tumor-killing capabilities, these CXCR2-augmented CAR-NK cells have the potential to overcome the challenges posed by the immunosuppressive tumor microenvironment, providing improved therapeutic outcomes.

Synergistic therapeutic combination with a CAF inhibitor enhances CAR-NK-mediated cytotoxicity via reduction of CAF-released IL-6

BACKGROUND

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME) contribute to an impaired functionality of natural killer (NK) cells that have emerged as a promising therapeutic modality. The interaction between CAFs and NK cells within the TME exerts major inhibitory effects on immune responses, indicating CAF-targeted therapies as potential targets for effective NK-mediated cancer killing.

METHODS

To overcome CAF-induced NK dysfunction, we selected an antifibrotic drug, nintedanib, for synergistic therapeutic combination. To evaluate synergistic therapeutic efficacy, we established an in vitro 3D Capan2/patient-derived CAF spheroid model or in vivo mixed Capan2/CAF tumor xenograft model. The molecular mechanism of NK-mediated synergistic therapeutic combination with nintedanib was revealed through in vitro experiments. In vivo therapeutic combination efficacy was subsequently evaluated. Additionally, the expression score of target proteins was measured in patient-derived tumor sections by the immunohistochemical method.

RESULTS

Nintedanib blocked the platelet-derived growth factor receptor β (PDGFRβ) signaling pathway and diminished the activation and growth of CAFs, markedly reducing CAF-secreted IL-6. Moreover, coadministration of nintedanib improved the mesothelin (MSLN) targeting chimeric antigen receptor-NK-mediated tumor killing abilities in CAF/tumor spheroids or a xenograft model. The synergistic combination resulted in intense NK infiltration in vivo. Nintedanib alone exerted no effects, whereas blockade of IL-6 trans-signaling ameliorated the function of NK cells. The combination of the expression of MSLN and the PDGFRβ⁺-CAF population area, a potential prognostic/therapeutic marker, was associated with inferior clinical outcomes.

CONCLUSION

Our strategy against PDGFRβ⁺-CAF-containing pancreatic cancer allows improvements in the therapy of pancreatic ductal adenocarcinoma.

Keratin 8 mutations in transgenic mice predispose to lung injury

Keratin 8 (K8) is the cytoskeletal intermediate filament protein of simple-type epithelia. Mutations in K8 predispose the affected individual and transgenic mouse to liver disease. However, the role of K8 in the lung has not been reported in mutant transgenic mouse models. Here, we investigated the susceptibility of two different transgenic mice expressing K8 Gly62-Cys (Gly62 replaced with Cys) or Ser74-Ala (Ser74 replaced with Ala) to lung injury. The mutant transgenic mice were highly susceptible to two independent acute and chronic lung injuries compared with control mice. Both K8 Gly62-Cys mice and K8 Ser74-Ala mice showed markedly increased mouse lethality (∼74% mutant mice versus ∼34% control mice) and more severe lung damage, with increased inflammation and apoptosis, under L-arginine-mediated acute lung injury. Moreover, the K8 Ser74-Ala mice had more severe lung damage, with extensive hemorrhage and prominent fibrosis, under bleomycin-induced chronic lung injury. Our study provides the first direct evidence that K8 mutations predispose to lung injury in transgenic mice.

Structural evolution of binder gel in alkali-activated cements exposed to electrically accelerated leaching conditions

The structural evolution of a binder gel in alkali-activated cements exposed to accelerated leaching conditions is investigated for the first time. Samples incorporating fly ash and/or slag were synthesized and were exposed to electrically accelerated leaching by applying a current density of 5 A/m². The leaching behavior of the samples greatly depended on the binder gel formed in the samples. The N-A-S-H type gel abundant in fly ash-rich samples showed some extent of dissolution upon accelerated leaching, while slag-rich samples underwent hydration of the anhydrous slag after leaching. The obtained results are discussed in view of the degradation of the binder gel induced by accelerated leaching, and their potential performance under repository conditions where groundwater-induced leaching is the main durability concern.

Keratins regulate Hsp70-mediated nuclear localization of p38 mitogen-activated protein kinase

Intermediate filament protein keratin 8 (K8) binds to heat shock protein 70 (Hsp70) and p38 MAPK, and is phosphorylated at Ser74 by p38α (MAPK14, hereafter p38). However, a p38 binding site on K8 and the molecular mechanism of K8-p38 interaction related to Hsp70 are unknown. Here, we identify a p38 docking site on K8 (Arg148/149 and Leu159/161) that is highly conserved in other intermediate filaments. A docking-deficient K8 mutation caused increased p38-Hsp70 interaction and enhanced p38 nuclear localization, indicating that the p38 dissociated from mutant K8 makes a complex with Hsp70, which is known as a potential chaperone for p38 nuclear translocation. Comparison of p38 MAPK binding with keratin variants associated with liver disease showed that the K18 I150V variant dramatically reduced binding with p38, which is similar to the effect of the p38 docking-deficient mutation on K8. Because the p38 docking site on K8 (Arg148/149 and Leu159/161) and the K18 Ile150 residue are closely localized in the parallel K8/K18 heterodimer, the K18 I150V mutation might interfere with K8-p38 interaction. These findings show that keratins, functioning as cytoplasmic anchors for p38, modulate p38 nuclear localization and thereby might affect a number of p38-mediated signal transduction pathways.

Liver disease-associated keratin 8 and 18 mutations modulate keratin acetylation and methylation

Keratin 8 (K8) and keratin 18 (K18) are the intermediate filament proteins whose phosphorylation/transamidation associate with their aggregation in Mallory-Denk bodies found in patients with various liver diseases. However, the functions of other post-translational modifications in keratins related to liver diseases have not been fully elucidated. Here, using a site-specific mutation assay combined with nano-liquid chromatography-tandem mass spectrometry, we identified K8-Lys108 and K18-Lys187/426 as acetylation sites, and K8-Arg47 and K18-Arg55 as methylation sites. Keratin mutation (Arg-to-Lys/Ala) at the methylation sites, but not the acetylation sites, led to decreased stability of the keratin protein. We compared keratin acetylation/methylation in liver disease-associated keratin variants. The acetylation of K8 variants increased or decreased to various extents, whereas the methylation of K18-del65-72 and K18-I150V variants increased. Notably, the highly acetylated/methylated K18-I150V variant was less soluble and exhibited unusually prolonged protein stability, which suggests that additional acetylation of highly methylated keratins has a synergistic effect on prolonged stability. Therefore, the different levels of acetylation/methylation of the liver disease-associated variants regulate keratin protein stability. These findings extend our understanding of how disease-associated mutations in keratins modulate keratin acetylation and methylation, which may contribute to disease pathogenesis.-Jang, K.-H., Yoon, H.-N., Lee, J., Yi, H., Park, S.-Y., Lee, S.-Y., Lim, Y., Lee, H.-J., Cho, J.-W., Paik, Y.-K., Hancock, W. S., Ku, N.-O. Liver disease-associated keratin 8 and 18 mutations modulate keratin acetylation and methylation.

A mutation in keratin 18 that causes caspase-digestion resistance protects homozygous transgenic mice from hepatic apoptosis and injury

Cytoskeletal keratin 18 (K18) undergoes caspase-mediated digestion during apoptosis, which leads to dramatic disassembly of keratin filaments. We studied the significance of K18 caspase digestion in a mouse model and generated transgenic mice expressing the human K18 caspase digestion-resistant double-mutant K18-D238/397E in a mouse (m) K18-null background, and compared their response to injury mediated by administration of antibody against tumor necrosis factor receptor superfamily member 6 (Fas), anti-FasAb. Notably, K18-D238/397E;mK18-null mice were significantly more resistant to anti-FasAb-induced injury as compared with K18-WT;mK18-null mice (23% vs 57% lethality, respectively; P<0.001). The same applied when the toxin microcystin-LR (MLR) was used to induce liver injury, i.e. lethality of K18-D238/397E;mK18-null mice in response to MLR treatment was reduced compared with the control mouse strain. The lesser rate of apoptosis in K18-D238/397E;mK18-null livers is associated with delayed degradation and, thus, sustained activation of cell-survival-related protein kinases, including stress-activated protein kinases and the NF-κB transcription factor, up to 6-8 h after administration of anti-FasAb. However, activation of the kinases and NF-κB in K18-WT-reconstituted livers decreases dramatically 8 h after anti-FasAb administration. In addition, the D238/397E double-mutation results in prolonged stability of K18 protein in transfected cells and transgenic livers. Therefore, our results show that the caspase digestion-resistant K18 helps to maintain keratin filament organization and delays apoptosis, thereby resulting in protection from liver injury.

Predisposition to apoptosis in keratin 8-null liver is related to inactivation of NF-κB and SAPKs but not decreased c-Flip

Keratin 8 and 18 (K8/K18) are major intermediate filament proteins of liver hepatocytes. They provide mechanical and nonmechanical stability, thereby protecting cells from stress. Hence, K8-null mice are highly sensitive to Fas-mediated liver cell apoptosis. However, the role of c-Flip protein in K8-null related susceptibility to liver injury is controversial. Here we analyzed c-Flip protein expression in various K8 or K18 null/mutant transgenic livers and show that they are similar in all analyzed transgenic livers and that previously reported c-Flip protein changes are due to antibody cross-reaction with mouse K18. Furthermore, analysis of various apoptosis- or cell survival-related proteins demonstrated that inhibition of phosphorylation of NF-κB and various stress activated protein kinases (SAPKs), such as p38 MAPK, p44/42 MAPK and JNK1/2, is related to the higher sensitivity of K8-null hepatocytes whose nuclear NF-κB is rapidly depleted through Fas-mediated apoptosis. Notably, we found that NF-κB and the studied protein kinases are associated with the K8/K18 complex and are released upon phosphorylation. Therefore, interaction of keratins with cell survival-related protein kinases and transcription factors is another important factor for hepatocyte survival.

Effects of estrogen on nitric oxide synthase and histological composition in the rabbit clitoris and vagina

We investigated the functional and histological changes after oophorectomy in the rabbit clitoris and vagina to determine the mechanism responsible for the development of arousal disorder in postmenopausal women. Twenty mature female New Zealand white rabbits were randomly divided into three groups: control; oophorectomy; and estrogen replacement after oophorectomy. We compared the nitric oxide synthase (NOS) activity and the degree of expression of neuronal (nNOS) and endothelial NOS (eNOS) using biochemical and Western blot analysis in clitoral and vaginal tissues. Histological change of smooth muscle and collagen contents in those tissues were also compared using Masson's trichrome staining. NOS activity and the expression of nNOS and eNOS were significantly increased in the oophorectomized group while there was a decrease to the level of the control group in the estrogen replacement group. Histological examination showed that oophorectomy induced a significant increase in collagen and decrease in muscle content in both clitoris and vagina, while the ratio of smooth muscle content was increased significantly after the estrogen replacement. Our results clearly demonstrate that estrogen deficiency induces compensatory NOS production which may be related to decreases in muscle to collagen ratio in female rabbit genital organs.