Functional crosstalk and regulation of natural killer cells in tumor microenvironment: Significance and potential therapeutic strategies

Impact of lactate on immune cell function in the tumor microenvironment: mechanisms and therapeutic perspectives

Lactate has emerged as a key regulator in the tumor microenvironment (TME), influencing both tumor progression and immune dynamics. As a byproduct of aerobic glycolysis, lactate satisfies the metabolic needs of proliferating tumor cells while reshaping the TME to facilitate immune evasion. Elevated lactate levels inhibit effector immune cells such as CD8+ T and natural killer cells, while supporting immunosuppressive cells, such as regulatory T cells and myeloid-derived suppressor cells, thus fostering an immunosuppressive environment. Lactate promotes epigenetic reprogramming, stabilizes hypoxia-inducible factor-1α, and activates nuclear factor kappa B, leading to further immunological dysfunction. In this review, we examined the role of lactate in metabolic reprogramming, immune suppression, and treatment resistance. We also discuss promising therapeutic strategies targeting lactate metabolism, including lactate dehydrogenase inhibitors, monocarboxylate transporter inhibitors, and TME neutralization methods, all of which can restore immune function and enhance immunotherapy outcomes. By highlighting recent advances, this review provides a theoretical foundation for integrating lactate-targeted therapies into clinical practice. We also highlight the potential synergy between these therapies and current immunotherapeutic strategies, providing new avenues for addressing TME-related challenges and improving outcomes for patients with cancer.

Identification of Natural Killer Cell-Associated Clusters in Skin Melanoma and the Impact on Prognosis and Drug Sensitivity

BACKGROUND

Skin melanoma exhibits significant heterogeneity in clinical outcomes and treatment responses among patients. This study aimed to investigate natural killer (NK) cell clusters in skin melanoma, their impact on patient prognosis, and their value as biomarkers for tailoring treatment.

METHODS

We used data from TCGA, GSE19234, GSE65904, GSE244982, and GSE78220. A gene classifier was developed to identify two distinct clusters of melanoma patients. Survival analysis, NK cell infiltration levels, and responses to immune and targeted therapies were evaluated.

RESULTS

Unsupervised clustering revealed two distinct melanoma patient clusters with significant differences in NK cell activity and clinical outcomes. Cluster 1 showed higher NK cell infiltration, better overall survival (OS) (p < 0.0001), and greater activity in NK-cell-related pathways. In contrast, Cluster 2, characterized by lower NK cell activity and higher exhaustion markers, had poorer OS. Drug sensitivity analysis indicated that Cluster 1 was more responsive to most melanoma treatments, whereas Cluster 2 had higher sensitivity to trametinib (p < 0.001). The developed gene classifier had an AUC of 0.913 and effectively differentiated between clusters. Additionally, Cluster 1 showed better responses to immunotherapy with a higher rate of complete and partial responses (p < 0.001). These findings were validated in external databases.

CONCLUSION

This study identifies two distinct NK-cell-related clusters in melanoma with differential prognoses and treatment responses. These findings underscore the importance of integrating NK-cell-related profiles into personalized treatment strategies, offering a pathway to optimize therapeutic outcomes based on specific immune profiles.

The diversity of natural killer cell functional and phenotypic states in cancer

The role of natural killer (NK) cells as immune effectors is well established, as is their utility as immunotherapeutic agents against various cancers. However, NK cells' anti-cancer roles are suppressed in cancer patients by various immunomodulatory mechanisms which alter these cells' identity, function, and potential for immunosurveillance. This manifests in abnormal NK cell responses accompanied by changes in phenotypic or genotypic identity, giving rise to specific NK cell subsets that are either hypofunctional or, more broadly, defective in their responses. Anergy, senescence, and exhaustion are some of the terms that have been used to define and characterize these NK cell functional states. These responses vary not only with cancer type but also NK cell location within tissues. Collectively, these phenomena suggest a highly plastic nature of NK cell biology in tumors. In this review, we present and discuss a summary of these functionally distinct states and provide an overview of how NK cells behave at different locations within the context of cancer.

SON-1010: an albumin-binding IL-12 fusion protein that improves cytokine half-life, targets tumors, and enhances therapeutic efficacy

Background

Cytokines have been promising cancer immunotherapeutics for decades, yet only two are licensed to date. Interleukin-12 (IL-12) is a potent regulator of cell-mediated immunity that activates NK cells and interferon-γ (IFNγ) production. It plays a central role in multiple pathways that can enhance cancer cell death and modify the tumor microenvironment (TME). Attempts to dose rIL-12 were initially successful but IFNγ toxicity in Phase 2 complicated further development in the late 1990s. Since then, better dosing strategies have been developed, but none have achieved the level of cancer control seen in preclinical models. We set out to develop a novel strategy to deliver fully functional IL-12 and other biologics to the TME by binding albumin, taking advantage of its ability to be concentrated and retained in the tumor.

Methods

Single-chain variable fragments (scFv) were identified from a human phage display library that bound human, mouse, and cynomolgus macaque serum albumin, both at physiologic and acidic conditions. These were taken through a series of steps to identify strongly binding molecules that don't interfere with the normal physiology of albumin to bind FcRn, giving it prolonged half-life in serum, along with SPARC/GP60, which allows albumin to target the TME. A final molecule was chosen and a single mutation was made that minimizes the potential for immunogenicity. This fully human albumin-binding (FHAB®) domain was characterized and manufacturing processes were developed to bring the first drug candidate into the clinic.

Results

Once identified, the murine form of mIL12-FHAB was studied preclinically to understand its mechanism of action and biodistribution. It was found to be much more efficient at blocking tumor growth compared to murine IL-12, while stimulating significant IFNγ production with minimal toxicity. SON-1010, which uses the human IL-12 sequence, passed through all of the characterization and required toxicology and is currently being studied in the clinic.

Conclusions

We identified and developed a platform technology with prolonged half-life that can target IL-12 and other immune modulators to the TME. Safety and efficacy are being studied using SON-1010 as monotherapy and in combination with checkpoint blockade strategies.

MiR-214 promotes the antitumor effect of NK cells in colorectal cancer liver metastasis through USP27X/Bim

Colorectal cancer (CRC) is a common tumor type, and liver metastasis reduces the long-term survival in CRC patients. Natural killer (NK) cells play an important role in anti-tumor immunity. The aim of this study was to investigate the mechanism of miR-214-5p on NK cells in CRC liver metastasis. We collected clinical samples of CRC liver metastasis and nonmetastatic tissues and purchased the human NK cell lines NK92 and liver metastatic CRC cells KM12L4 for research. RT‒qPCR, Western blot, CCK-8, Transwell, and flow cytometry methods were used to evaluate the effect of miR-214-5p/USP27X/Bim pathway regulating NK cell activity on CRC liver metastasis. In addition, we also investigated the potential targets and regulatory mechanisms of the signaling pathway of miR-214-5p. In this study, we found that miR-214-5p was downregulated in CRC liver metastasis tissues. After transfection of miR-214-5p mimic, the activity of NK cells was significantly enhanced, and the proliferation and migration ability of CRC liver metastasis cells were inhibited, while inducing tumor cell apoptosis. Further research proved that USP27X is a potential target for miR-214-5p and upregulates Bim level through deubiquitination. In addition, miR-214-5p mimic reduced the level of USP27X and Bim, thereby enhancing the antitumor effect of NK cells. In conclusion, our research results show that miR-214-5p promotes the antitumor effect of NK cells by regulating the USP27X/Bim pathway, thereby inhibiting CRC liver metastasis. This finding reveals the important role of miR-214-5p in regulating the immune function of NK cells, and provides new ideas for developing new immunotherapy strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00642-1.

Accumulation of CD56+ CD16- Natural Killer Cells in Response to Preoperative Chemotherapy for Breast Cancer

Background

The activation of the antitumor immune responses of T cells and natural killer (NK) cells is important to induce breast tumor shrinkage via preoperative chemotherapy. We evaluated how antitumor immune responses contribute to the effects of such therapy.

Methods

Forty-three patients with stages I - IV breast cancer who underwent surgery between August 2018 and Jun 2023 after preoperative chemotherapy were enrolled. Peripheral natural killer (pNK) cell activity was assessed by 51Cr-release assay, and the counts and percentages of CD4+, CD8+, and NK cells and their subsets in peripheral blood were measured before and after chemotherapy by two-color flow cytometry. Associations of cell population changes with chemotherapy responses were analyzed.

Results

On univariate analysis, relative to grade (G) ≤ 1 effects, G ≥ 2 therapeutic effects were associated significantly with human epidermal growth factor receptor 2 (HER-2)+ breast cancer (P = 0.024) and post-chemotherapy CD56+ CD16- NK cell accumulation (8.4% vs. 5.5%, P = 0.042), and tended to be associated with increased pre-chemotherapy CD56+ CD16- NK cell percentages (5.4% vs. 3.3%, P = 0.054) and pNK cell activity (42.0% vs. 34.5%, P = 0.057). The accumulation and increased percentage of CD56+ CD16- NK cells in patients with G ≥ 2 effects were not associated with changes in pNK cell activity or the disappearance of axillary lymph-node metastases. On multivariate analysis, G ≥ 2 therapeutic effects tended to be associated with higher pre-chemotherapy pNK levels (odds ratio = 0.96; 95% confidence interval: 0.921 - 1.002; P = 0.067).

Conclusions

The accumulation of the immunoregulatory CD56+ CD16- NK cell subset in the peripheral blood before and after chemotherapy may lead to the production of cytokines that induce an antitumor immune response. Activation of the immune response mediated by CD56+ CD16- pNK cells after chemotherapy and their high counts before chemotherapy may contribute to the improvement of therapeutic effects against breast cancer.

Cell-mediated barriers in cancer immunosurveillance

The immune cells within the tumor microenvironment (TME) exert multifaceted functions ranging from tumor-antagonizing or tumor-promoting activities. During the initial phases of tumor development, the tumor-antagonizing immune cells in the TME combat cancer cells in an immune surveillance process. However, with time, cancer cells can evade detection and impede the immune cells' effectiveness through diverse mechanisms, such as decreasing immunogenic antigen presentation on their surfaces and/or secreting anti-immune factors that cause tolerance in TME. Moreover, some immune cells cause immunosuppressive situations and inhibit antitumoral immune responses. Physical and cellular-mediated barriers in the TME, such as cancer-associated fibroblasts, tumor endothelium, the altered lipid composition of tumor cells, and exosomes secreted from cancer cells, also mediate immunosuppression and prevent extravasation of immune cells. Due to successful clinical outcomes of cancer treatment strategies the potential barriers must be identified and addressed. We need to figure out how to optimize cancer immunotherapy strategies, and how to combine therapeutic approaches for maximum clinical benefit. This review provides a detailed overview of various cells and molecules in the TME, their association with escaping from immune surveillance, therapeutic targets, and future perspectives for improving cancer immunotherapy.

Nanoparticle-based immunoengineering strategies for enhancing cancer immunotherapy

Cancer immunotherapy is a groundbreaking strategy that has revolutionized the field of oncology compared to other therapeutic strategies, such as surgery, chemotherapy, or radiotherapy. However, cancer complexity, tumor heterogeneity, and immune escape have become the main hurdles to the clinical application of immunotherapy. Moreover, conventional immunotherapies cause many harmful side effects owing to hyperreactivity in patients, long treatment durations and expensive cost. Nanotechnology is considered a transformative approach that enhances the potency of immunotherapy by capitalizing on the superior physicochemical properties of nanocarriers, creating highly targeted tissue delivery systems. These advantageous features include a substantial specific surface area, which enhances the interaction with the immune system. In addition, the capability to finely modify surface chemistry enables the achievement of controlled and sustained release properties. These advances have significantly increased the potential of immunotherapy, making it more powerful than ever before. In this review, we introduce recent nanocarriers for application in cancer immunotherapy based on strategies that target different main immune cells, including T cells, dendritic cells, natural killer cells, and tumor-associated macrophages. We also provide an overview of the role and significance of nanotechnology in cancer immunotherapy.

NK cells direct the perspective approaches to cancer immunotherapy

Natural killer (NK) cells are innate immune cells with cytotoxic potentials to kill cancerous cells in several mechanisms, which could be implied for cancer therapy. While potent, their antitumor activities specially for solid tumors impaired by inadequate tumor infiltration, suppressive tumor microenvironment, cancer-associated stroma cells, and tumor-supportive immune cells. Therefore, manipulating or reprogramming these barriers by prospective strategies might improve current immunotherapies in the clinic or introduce novel NK-based immunotherapies. NK-based immunotherapy could be developed in monotherapy or in combination with other therapeutic regimens such as oncolytic virus therapy and immune checkpoint blockade, as presented in this review.