Augmenting Efficacy of T-Cell Bispecific Antibodies in AML through a Tumor Stroma-Targeted 4-1BB Agonist

Bispecific antibodies represent a promising treatment option for acute myeloid leukemia (AML). We have recently described a novel T-cell bispecific antibody (TCB) targeting the intracellular tumor antigen Wilms tumor 1 (WT1) in the context of HLA-A*02 (Augsberger et al. Blood 2021). Based on these findings a multicenter first-in-human clinical trial was initiated in relapse/refractory AML (NCT04580121). Possible immune escape mechanisms against T-cell based immunotherapy are provided by the tumor microenvironment (TME) of the bone marrow by co-inhibition of T cells or stromal cells shielding leukemic cells from immune effector cells. To overcome the immunosuppressive effect of the TME and to enhance T-cell responses, we evaluated the combination of the WT1-TCB with an antibody fusion protein that targets a stromal antigen (Fibroblast-activation protein; FAP) and provides a positive costimulatory signal (4-1BBL) to T cells. FAP is upregulated on cancer-associated fibroblasts after remodulation of the bone marrow niche by leukemic cells, and the FAP specificity of the molecule therefore provides T-cell co-stimulation tightly restricted to the tumor niche. Efficacy of the combination (WT1-TCB + FAP-4-1BBL antibody fusion protein) was evaluated in co-culture assays over 4 days with primary HLA-A*02 + AML cells, healthy donor (HD) T cells and three NIH-3T3 fibroblast cell lines. NIH-3T3 cell lines were genetically modified to express low and high levels of FAP, respectively. Wild-type NIH-3T3 cells were included as control. Additionally, a control (Ctrl)-TCB and a Ctrl-4-1BBL antibody fusion protein recognizing a non-tumor target derived from the human germline repertoire were included. Enhancement of T-cell mediated cytotoxicity by the FAP-4-1BBL antibody fusion protein was evaluated by (1) specific lysis of primary AML cells, (2) upregulation of the T-cell activation markers CD25 and 4-1BB, (3) T-cell expansion calculated as fold change compared to day 0, and (4) Granzyme B-expression which was evaluated by intracellular staining. After 4 days of co-culture, with an E:T ratio of 1:2, we observed a mean specific lysis of 55.1±8.2% (±SEM; n=4) of primary AML cells mediated by HD T cells and WT1-TCB. Notably, this was reduced to 19.4±5.9% (±SEM; n=4) in the presence of NIH-3T3 cells. However, AML cell lysis was restored by the addition of the FAP-4-1BBL antibody fusion protein in the presence of high FAP expressing NIH-3T3 cells (mean specific lysis: 62.8±7.3%; ±SEM; n=4). Concomitantly, the FAP-4-1BBL antibody fusion protein led to increased expression of the activation molecules CD25 (MFI ratio: 22.1±5.3 vs. 10.4±1.3; ±SEM; n=4) and 4-1BB (MFI ratio: 10.4±6.0 vs. 2.1±0.3; ±SEM; n=4) on CD3 + T cells. Furthermore, lysis was accompanied by increased frequencies of granzyme B expressing T cells (45.0±2.5% vs. 16.1±5.3%; n=3). Importantly, the FAP-4-1BBL antibody fusion protein led to improved T-cell proliferation, especially of CD8 + T cells (fold change on day 4 vs day 0: 5.7±2.2 vs. 1.0±0.3; ±SEM; n=4). Overall similar observations were made in the presence of low FAP expressing NIH-3T3 cells. Taken together, we have established an in vitro model system mimicking the immunoprotective bone marrow TME using NIH-3T3 cells resulting in impaired AML cell lysis. Providing additional T-cell co-stimulation by a tumor-stroma targeted 4-1BB agonist, however, restored WT1-TCB-mediated cytotoxicity of primary AML cells in the presence of FAP expressing cell lines. Importantly, the combination overcame the immunosuppressive effect of the NIH-3T3 cells on T cells as further demonstrated by improved T-cell activation and expansion. The tumor-stroma targeted 4-1BB agonist therefore represents a promising combinatorial approach to enhance T-cell activity at the local tumor site and warrants further investigations in an in vivo model system. Disclosures Pulko: Roche: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties. Claus: Roche: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties. Buecklein: Pfizer: Consultancy, Honoraria, Speakers Bureau; Kite/Gilead: Consultancy, Honoraria, Other: Congress and travel support, Research Funding; Novartis: Consultancy, Other: congress and travel support, Research Funding, Speakers Bureau; Miltenyi: Research Funding; BMS/Celgene: Consultancy, Research Funding; Amgen: Consultancy, Honoraria. Umana: Roche: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties. Klein: Roche: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties. Subklewe: Novartis: Consultancy, Research Funding, Speakers Bureau; Klinikum der Universität München: Current Employment; Roche: Research Funding; Seattle Genetics: Consultancy, Research Funding; Pfizer: Consultancy, Speakers Bureau; Janssen: Consultancy; Takeda: Speakers Bureau; MorphoSys: Research Funding; Miltenyi: Research Funding; Gilead: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Research Funding, Speakers Bureau; BMS/Celgene: Consultancy, Research Funding, Speakers Bureau.

In-vitro Wound Healing Properties of Commiphora swynnertonii Resinous Extracts

Wound healing is a complex multicellular process involving many cell types which include; inflammatory cells, endothelial cells, fibroblasts and keratinocytes. The process involves an orderly sequence of events with four overlapping phases namely; haemostasis, inflammatory, proliferation and remodeling phases. The process can be facilitated by the use of wound healing agents including herbal remedies from plants. In this study the main objective was to evaluate the in vitro wound healing activity of the resin obtained from Commiphora swynnertonii (C.swynnertonii). First the NIH -3T3 cells viability were evaluated using (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyl Tetrazolium Bromide (MTT) assay. Then the wound scratch assay model was used to evaluate cellular proliferation, closure of the wound and release of matrix metalloproteinase enzymes. Results indicate differences in mean cell viability between different concentrations within 24 hours of incubation. The highest viability was recorded at the concentration of 1% (v/v). The in-vitro wound scratch assay showed positive NIH - 3T3 cells proliferation on the wound area and cells migration when compared with control group (without treatment) at 0 and 24 hours. In addition, C. swynnertonii was able to stimulate secretion of MMP-2 release from NIH - 3T3 cells. MMP-2 is an important enzyme for extracellular matrix remodeling during wound healing suggesting that C. swynnertonii promotes wound healing by stimulating cell proliferation and production of MMP-2 in a mechanism that is currently not known.

MicroRNA-27a-3p promotes proliferation and migration by up-regulation of perlecan in murine fibroblast cell line NIH/3T3

IntroductionSkin scar is a common cutaneous complication, the outcome of which is unpleasant. Several microRNAs (miRs) participate in the process of skin scar formation. We aimed to explore the role of miR-27a-3p in NIH/3T3 mouse fibroblasts as well as the downstream protein and signaling cascades.Material and methodsmiR-27a-3p was aberrantly expressed in NIH/3T3 cells, followed by measurements of cell viability, migration and expressions of proteins related to proliferation and migration. Perlecan expression in cells aberrantly expressing miR-27a-3p was examined by Western blot analysis. Reporter gene assay was conducted to assess the relationship between miR-27a-3p and perlecan. Then, whether miR-27a-3p affected NIH/3T3 cells through regulating perlecan was ascertained. The effects of aberrantly expressed miR-27a-3p and perlecan on expression levels of VEGF, bFGF and key kinases in the MAPK/ERK and the PI3K/AKT pathways were detected.ResultsCell viability and migration were enhanced and protein expression levels of Cyclin D1, MMP-2 and MMP-9 were up-regulated by miR-27a-3p overexpression in NIH/3T3 cells. Then, we found that perlecan was positively correlated with miR-27a-3p expression, and its knockdown abrogated the effects of miR-27a-3p overexpression on NIH/3T3 cells. Finally, we found that the expression levels of VEGF and bFGF as well as phosphorylated levels of MAPK, ERK, PI3K and AKT were increased by miR-27a-3p overexpression, and those increases were reversed by perlecan knockdown.ConclusionsmiR-27a-3p promotes proliferation and migration of NIH/3T3 cells through up-regulating perlecan expression. Meanwhile, miR-27a-3p up-regulates expression levels of VEGF and bFGF, and activates MAPK/ERK and PI3K/AKT pathways through up-regulating perlecan expression.

Quantum dots as targeted doxorubicin drug delivery nanosystems

Background Lung cancer is one of the most frequently diagnosed cancers all over the world and is also one of the leading causes of cancer-related mortality. The main treatment option for small cell lung cancer, conventional chemotherapy, is characterized by a lack of specificity, resulting in severe adverse effects. Therefore, this study aimed at developing a new targeted drug delivery (TDD) system based on Ag–In–Zn–S quantum dots (QDs). For this purpose, the QD nanocrystals were modified with 11-mercaptoundecanoic acid (MUA), L-cysteine, and lipoic acid decorated with folic acid (FA) and used as a novel TDD system for targeting doxorubicin (DOX) to folate receptors (FARs) on adenocarcinomic human alveolar basal epithelial cells (A549). NIH/3T3 cells were used as FAR-negative controls. Comprehensive physicochemical, cytotoxicity, and genotoxicity studies were performed to characterize the developed novel TDDs. Results Fourier transformation infrared spectroscopy, dynamic light scattering, and fluorescence quenching confirmed the successful attachment of FA to the QD nanocrystals and of DOX to the QD–FA nanocarriers. UV–Vis analysis helped in determining the amount of FA and DOX covalently anchored to the surface of the QD nanocrystals. Biological screening revealed that the QD–FA–DOX nanoconjugates had higher cytotoxicity in comparison to the other forms of synthesized QD samples, suggesting the cytotoxic effect of DOX liberated from the QD constructs. Contrary to the QD–MUA–FA–DOX nanoconjugates which occurred to be the most cytotoxic against A549 cells among others, no such effect was observed for NIH/3T3 cells, confirming FARs as molecular targets. In vitro scratch assay also revealed significant inhibition of A549 cell migration after treatment with QD–MUA–FA–DOX. The performed studies evidenced that at IC50 all the nanoconjugates induced significantly more DNA breaks than that observed in nontreated cells. Overall, the QD–MUA–FA–DOX nanoconjugates showed the greatest cytotoxicity and genotoxicity, while significantly inhibiting the migratory potential of A549 cells. Conclusion QD–MUA–FA–DOX nanoconjugates can thus be considered as a potential drug delivery system for the effective treatment of adenocarcinomic human alveolar basal epithelial cells.

Chemical constituents of Eremomastax speciosa (Hochst.) Cufod leaves and its cytotoxic potential on NIH-3T3 cells

This study aimed at assessing the cytotoxicity of Eremomastax speciosa crude extract on NIH-3T3 fibroblast cell lines and reporting the chemical constituents in the extract. The MTT assay on NIH-3T3 cells showed a significantly lower (p < 0.05) inhibition from E. speciosa (IC50 > 30 µg/mL) compared to cyclohexamide (IC50 > 0.8 µg/mL). This result validates the non-toxicity observed with the use of E. speciosa on normal cells at low to moderate doses. Four compounds were isolated and identified from their EIMS as well as 1D and 2D NMR spectroscopic data namely hydroxyandrographolide (1), stigmasterol glucoside (2), (Z)-4-coumaric acid 4-O-β-D-apiofuranosyl-(1’’→2’)-O-β-D-glucopyranoside (3) and 5-methoxy-4,4′-di-O-methyl- secolariciresinol-9′-monoacetate (4). These compounds are isolated from this species for the first time. Thirteen volatile constituents were detected in the extract using gas chromatography mass spectrometry (GC-MS). Besides 6,10,14-trimethy-2-pentadecanone (12.63%), mostly fatty acid esters were detected in high amounts notably ethyl hexadecanoate (16.00%), ethyl-9,12,15-octadecatrienoate (11.51%) and 9,12-octadecadienoic acid ethyl ester (8.05%). This study revealed many unsaturated fatty acid esters in E. speciosa and is noteworthy that ω-3 and ω-6 fatty acid esters were predominant, hence an added nutritional value to this plant. KEY WORDS: Eremomastax speciosa, Secondary metabolites, NIH-3T3 cytotoxicity, NMR, GC-MS Bull. Chem. Soc. Ethiop. 2020, 34(3), 633-640. DOI: https://dx.doi.org/10.4314/bcse.v34i3.18

Acrolein Contributes to Human Colorectal Tumorigenesis Through Activation of RAS/MAPK Pathway

Background. Colorectal cancer (CRC) is one of the most well-known malignancies with high prevalence and poor 5-year survival. Previous studies have demonstrated that intake of food rich in fat, and with low fiber content (as known as high-fat diet, HFD) is capable of increasing the odds of developing CRC. Acrolein, an IARC group 2A carcinogen, can be formed by thermal treatment of animal and vegetable fats, carbohydrates and amino acids through Maillard reaction. Also, acrolein has been shown to be produced from microbial glycerol metabolism in human gut. Consequently, humans are at risk of acrolein exposure through consumption of foods rich in fat. However, whether acrolein contributes to HFD-induced CRC tumorigenesis remains elusive.Methods. The effect of acrolein in oncogenic transformation was analyzed using NIH/3T3 cells with xenograft tumorigenesis mice models. Furthermore, cDNA microarray analysis with Ingenuity Pathway Analysis (IPA) was performed in acrolein-transformed NIH/3T3 cells. Finally, acrolein-induced DNA damages (Acr-dG) were analyzed in tumor tissues and normal epithelial of CRC patients using immunohistochemical analysis. The levels of Acr-dG adducts were associated with tumor characteristics and CRC patients’ survival using Chi-Square analysis and Kaplan Meier survival analysis, respectively.Results. In this present study, we found that acrolein induced oncogenic transformation including faster cell cycling, proliferation, soft agar formation, sphere formation, cell migration in NIH/3T3 cells. Using xenograft tumorigenicity assays, the acrolein-transformed NIH3T3 clone formed tumors whereas no tumors were observed in mice inoculated with NIH3T3 parental cells. In addition, RAS/MAPK pathway contributing to colon tumorigenesis was activated in NIH/3T3 Acr-clone using cDNA microarray analysis with IPA. Finally, Acr-dG adducts were higher in CRC tumor tissues compared to normal epithelial cells in CRC patients. Intriguingly, CRC patients with higher Acr-dG adducts have better prognosis. Conclusions. Taken together, this is the first study to demonstrate that acrolein is important in oncogenic transformation through activating RAS/MAPK signaling pathway contributing to colon tumorigenesis. Thus, acrolein might be a novel target for early detection, prevention and treatment of tumors in the future.