Venetoclax enhances NK cell killing sensitivity of AML cells through the NKG2D/NKG2DL activation pathway

Resveratrol contributes to NK cell-mediated breast cancer cytotoxicity by upregulating ULBP2 through miR-17-5p downmodulation and activation of MINK1/JNK/c-Jun signaling

BACKGROUNDS

Natural killer (NK) cell mediated cytotoxicity is a crucial form of anti-cancer immune response. Natural killer group 2 member D (NKG2D) is a prominent activating receptor of NK cell. UL16-binding protein 2 (ULBP2), always expressed or elevated on cancer cells, functions as a key NKG2D ligand. ULBP2-NKG2D ligation initiates NK cell activation and subsequent targeted elimination of cancer cells. Enhanced expression of ULBP2 on cancer cells leads to more efficient elimination of these cells by NK cells. Resveratrol (RES) is known for its multiple health benefits, while current understanding of its role in regulating cancer immunogenicity remains limited. This study aims to investigate how RES affects the expression of ULBP2 and the sensitivity of breast cancer (BC) cells to NK cell cytotoxicity, along with the underlying mechanisms.

METHODS

The effects of RES on ULBP2 expression were detected with qRT-PCR, western blot, flow cytometry analysis and immunohistochemistry. The effects of RES on sensitivity of BC cells to NK cell cytotoxicity were evaluated in vitro and in vivo. The target gene of miR-17-5p were predicted with different algorithms from five databases and further confirmed with dual-luciferase reporter assay. Overexpression and knockdown experiments of miR-17-5p and MINK1 were conducted to investigate their roles in regulating ULBP2 expression and subsequent JNK/c-Jun activation. The JNK inhibitor sp600125 was utilized to elucidate the specific role of JNK in modulating ULBP2 expression.

RESULTS

RES increased ULBP2 expression on BC cells, thereby augmenting their vulnerability to NK cell-mediated cytotoxicity both in vitro and in vivo. RES administration led to a reduction in cellular miR-17-5p level. MiR-17-5p negatively regulated ULBP2 expression. Specifically, miR-17-5p directly targeted MINK1, leading to its suppression. MINK1 played a role in facilitating the activation of JNK and its downstream effector, c-Jun. Furthermore, treatment with sp600125, a JNK inhibitor, resulted in the suppression of ULBP2 expression.

CONCLUSIONS：

RES potentiates ULBP2-mediated immune eradication of BC cells by NK cells through the downregulation of miR-17-5p and concurrent activation of the MINK1/JNK/c-Jun cascade. This finding identifies RES as a potentially effective therapeutic agent for inhibiting BC progression and optimizing NK cell-based cancer immunotherapy.

Immunotherapy of osteosarcoma based on immune microenvironment modulation

Osteosarcoma is a highly malignant tumor with unsatisfactory therapeutic outcomes achieved by chemotherapy, radiotherapy, and surgery. As an emerging oncological treatment, immunotherapy has shown potential in the clinical management of many tumors but has a poor response rate in osteosarcoma. The immunosuppressive microenvironment in osteosarcoma is the main reason for the ineffectiveness of immunotherapy, in which the low immune response rate of immune effector cells and the high activation of immunosuppressive cells contribute to this outcome. Therefore, modulating the function of the immune microenvironment in osteosarcoma is expected to remodel the immunosuppressive microenvironment of osteosarcoma and enhance the efficacy of immunotherapy. This article reviews the role of immune cells in the progression of osteosarcoma, describes the corresponding regulatory tools for the characteristics of different cells to enhance the efficacy of osteosarcoma immunotherapy, and concludes the prospects and future challenges of osteosarcoma immunotherapy.

Immunosuppressive microenvironment in acute myeloid leukemia: overview, therapeutic targets and corresponding strategies

Similar to other malignancies, immune dysregulation is a key feature of acute myeloid leukemia (AML), manifesting as suppressed anti-leukemia immune cells, immune evasion by leukemia blasts, and disease progression. Various immunosuppressive factors within the AML microenvironment contribute to the weakening of host immune responses and the efficacy of cellular immunotherapy. To address these challenges, strategies targeting immunosuppressive elements within the AML microenvironment aim to bolster host or adoptive immune effector cells, ultimately enhancing leukemia treatment. Additionally, the off-target effects of certain targeted drugs (venetoclax, sorafenib, ivosidenib, etc.) may also positively impact anti-AML immunity and immunotherapy. This review provides an overview of the immunosuppressive factors present in AML microenvironment and the strategies developed to rescue immune cells from immunosuppression. We also outline how targeted agents can alter the immune landscape in AML patients, and discuss the potential of targeted drugs to benefit host anti-leukemia immunity and immunotherapy for AML.

Natural killer cell biology and therapy in multiple myeloma: challenges and opportunities

Despite therapeutic advancements, multiple myeloma (MM) remains incurable. NK cells have emerged as a promising option for the treatment of MM. NK cells are heterogenous and typically classified based on the relative expression of their surface markers (e.g., CD56 and CD16a). These cells elicit an antitumor response in the presence of low mutational burden and without neoantigen presentation via germline-encoded activating and inhibitory receptors that identify the markers of transformation present on the MM cells. Higher NK cell activity is associated with improved survival and prognosis, whereas lower activity is associated with advanced clinical stage and disease progression in MM. Moreover, not all NK cell phenotypes contribute equally toward the anti-MM effect; higher proportions of certain NK cell phenotypes result in better outcomes. In MM, the proportion, phenotype, and function of NK cells are drastically varied between different disease stages; this is further influenced by the bone marrow microenvironment, proportion of activating and inhibitory receptors on NK cells, expression of homing receptors, and bone marrow hypoxia. Antimyeloma therapies, such as autologous stem cell transplant, immunomodulation, proteasome inhibition, and checkpoint inhibition, further modulate the NK cell landscape in the patients. Thus, NK cells can naturally work in tandem with anti-MM therapies and be strategically modulated for improved anti-MM effect. This review article describes immunotypic and phenotypic differences in NK cells along with the functional changes in homeostatic and malignant states and provides expert insights on strategies to harness the potential of NK cells for improving outcomes in MM.

Combination of BCL-2 inhibitors and immunotherapy: a promising therapeutic strategy for hematological malignancies

The rapid development of high-throughput sequencing in recent years has facilitated great progress in the molecular-targeted therapy of hematological malignancies, including leukemia, lymphoma, and multiple myeloma. BCL-2 inhibitors are among the most important molecular-targeted agents. Immunotherapy for hematologic malignancy has rapidly increased in popularity in recent years and has been proven to improve the overall survival rate. However, few clinical studies have investigated combination therapy with BCL-2 inhibitors and immunotherapies, such as immune molecule-targeted drugs or immune cell adoptive therapy. In this review, we discuss the drug discovery process, current clinical application status, and resistance and tolerance issues associated with BCL-2 inhibitors. We emphasize their important role in regulating the immune system and propose that the combination of BCL-2 inhibitors with immunotherapy may be one of the most promising treatment methods for hematologic malignancies.

Venetoclax acts as an immunometabolic modulator to potentiate adoptive NK cell immunotherapy against leukemia

Natural killer (NK) cell-based immunotherapy holds promise for cancer treatment; however, its efficacy remains limited, necessitating the development of alternative strategies. Here, we report that venetoclax, an FDA-approved BCL-2 inhibitor, directly activates NK cells, enhancing their cytotoxicity against acute myeloid leukemia (AML) both in vitro and in vivo, likely independent of BCL-2 inhibition. Through comprehensive approaches, including bulk and single-cell RNA sequencing, avidity measurement, and functional assays, we demonstrate that venetoclax increases the avidity of NK cells to AML cells and promotes lytic granule polarization during immunological synapse (IS) formation. Notably, we identify a distinct CD161lowCD218b+ NK cell subpopulation that exhibits remarkable sensitivity to venetoclax treatment. Furthermore, venetoclax promotes mitochondrial respiration and ATP synthesis via the NF-κB pathway, thereby facilitating IS formation in NK cells. Collectively, our findings establish venetoclax as a multifaceted immunometabolic modulator of NK cell function and provide a promising strategy for augmenting NK cell-based cancer immunotherapy.

Advances in molecular targeted drugs in combination with CAR-T cell therapy for hematologic malignancies

Molecular targeted drugs and chimeric antigen receptor (CAR) T cell therapy represent specific biological treatments that have significantly improved the efficacy of treating hematologic malignancies. However, they face challenges such as drug resistance and recurrence after treatment. Combining molecular targeted drugs and CAR-T cells could regulate immunity, improve tumor microenvironment (TME), promote cell apoptosis, and enhance sensitivity to tumor cell killing. This approach might provide a dual coordinated attack on cancer cells, effectively eliminating minimal residual disease and overcoming therapy resistance. Moreover, molecular targeted drugs can directly or indirectly enhance the anti-tumor effect of CAR-T cells by inducing tumor target antigen expression, reversing CAR-T cell exhaustion, and reducing CAR-T cell associated toxic side effects. Therefore, combining molecular targeted drugs with CAR-T cells is a promising and novel tactic for treating hematologic malignancies. In this review article, we focus on analyzing the mechanism of therapy resistance and its reversal of CAR-T cell therapy resistance, as well as the synergistic mechanism, safety, and future challenges in CAR-T cell therapy in combination with molecular targeted drugs. We aim to explore the benefits of this combination therapy for patients with hematologic malignancies and provide a rationale for subsequent clinical studies.

Research Hotspots and Trends of NK Cell Immunotherapy for Acute Myeloid Leukemia: A Bibliometric Analysis From 2000 to 2023

BACKGROUND

Natural killer (NK) cell immunotherapy has shown promising therapeutic potential for acute myeloid leukemia (AML), especially with advancements in chimeric antigen receptor-engineered NK cells (CAR-NK) and artificial intelligence (AI). Despite these developments, the field lacks comprehensive bibliometric analyses to identify research hotspots and trends, which could guide future precision treatments.

METHODS

A bibliometric analysis of NK cell immunotherapy for AML was conducted using literature from 2000 to 2023 retrieved from the Web of Science Core Collection database. Data visualization tools like CiteSpace, VOSviewer, and RStudio were employed to analyze publication trends, country contributions, institutional collaborations, influential authors, and research themes.

RESULTS

The analysis identified 1513 studies, with the United States and China leading global contributions. Notable institutions include the University of Minnesota and MD Anderson Cancer Center. Hot topics include allogeneic NK therapy, CAR-NK cell therapy, and memory-like NK cells. Emerging trends highlight the integration of intelligent NK cells and combinatory therapies, offering promising avenues for AML treatment. Despite progress, challenges such as NK cell expansion, activation, and resistance mechanisms remain critical areas for research.

CONCLUSION

This study provides a comprehensive overview of the research landscape, highlighting the transformative potential of NK cell immunotherapy in AML. It underscores the need for international collaboration and continued innovation to overcome existing challenges and advance precision therapies.

Selinexor Synergistically Promotes the Antileukemia Activity of Venetoclax in Acute Myeloid Leukemia by Inhibiting Glycolytic Function and Downregulating the Expression of DNA Replication Genes

Introduction

The BCL-2 inhibitor venetoclax has been widely used in the treatment of acute myeloid leukemia (AML); however, AML patients treated with venetoclax gradually develop resistance. The exportin-1 (XPO1) inhibitor selinexor can synergistically promote the antileukemia activity of venetoclax, but the mechanism remains unclear.

Methods and Results

Annexin V/7-aminoactinomycin D assays were used to examine the effects of a combination of venetoclax and selinexor (VEN+SEL) on AML cell lines and primary AML cells. RNA sequencing and oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) determinations by a Seahorse XF analyzer were employed to investigate the molecular mechanism of the toxicity of the VEN+SEL combination to AML cells. The cytotoxicity of NK cell combined with VEN+SEL combination was assessed in vitro using flow cytometry. VEN+SEL enhanced the apoptosis of AML cells (KG-1A and THP-1) and primary AML samples in vitro. The ECAR and OCR results demonstrated that the VEN+SEL combination significantly inhibited glycolytic function. RNA sequencing of THP-1 cells demonstrated that DNA replication-related genes were downregulated after treatment with the VEN+SEL combination.

Conclusion

This study indicated that selinexor can synergistically enhance the antileukemia activity of venetoclax in AML cells in vitro by inhibiting glycolytic function and downregulating DNA replication-related genes. Based on our experimental data, combining selinexor with venetoclax is an appropriate advanced treatment option for AML patients.

The BCL-2 Inhibitor Venetoclax Augments Immune Effector Function Mediated by Fas Ligand, TRAIL, and Perforin/Granzyme B, Resulting in Reduced Plasma Viremia and Decreased HIV Reservoir Size during Acute HIV Infection in a Humanized Mouse Model

The BCL-2 prosurvival protein is implicated in HIV persistence and is a potential therapeutic target for HIV eradication efforts. We now know that cells harboring HIV are preferentially enriched for high BCL-2 expression, enabling their survival, and that the BCL-2 inhibitor venetoclax promotes the death of actively replicating HIV-infected cells in vitro and ex vivo. Herein, we assess the effect of venetoclax on immune clearance of infected cells and show that BCL-2 inhibition significantly enhances target cell killing induced by Fas ligand, TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), and perforin/granzyme B and synergistically enhances autologous NK (natural killer) and CD8 cells' killing of target cells. In a humanized mouse model of acute HIV infection, venetoclax monotherapy significantly decreases plasma viremia and normalizes CD4:CD8 ratios, and results in more mice with undetectable provirus levels than control. In this model, treatment was associated with leukopenia, as has been described clinically in patients receiving venetoclax for other indications. These data confirm meaningful anti-HIV effects of venetoclax during HIV infection but suggest that venetoclax use should be combined with ART (antiretroviral therapy) to reduce toxicity. IMPORTANCE This study is the first to examine the applicability of BCL-2 inhibition in the setting of active HIV infection in vivo. Furthermore, this study demonstrates that venetoclax significantly enhances target cell killing induced by Fas ligand, TRAIL, and perforin/granzyme B and synergistically enhances autologous NK and CD8 cells' killing of target cells.

Prime, shock and kill: BCL-2 inhibition for HIV cure

While modern HIV therapy can effectively suppress viral replication, the persistence of the latent reservoir posits the greatest hurdle to complete cure. The "shock and kill" strategy is under investigation for HIV therapy, aiming to reactivate latent HIV, and subsequently eliminate it through anti-retroviral therapy and host immune function. However, thus far, studies have yielded suboptimal results, stemming from a combination of ineffective latency reversal and poor immune clearance. Concomitantly, studies have now revealed the importance of the BCL-2 anti-apoptotic protein as a critical mediator of infected cell survival, reservoir maintenance and immune evasion in HIV. Furthermore, BCL-2 inhibitors are now recognized for their anti-HIV effects in pre-clinical studies. This minireview aims to examine the intersection of BCL-2 inhibition and current shock and kill efforts, hoping to inform future studies which may ultimately yield a cure for HIV.