Evaluation of HLA-E Expression Combined with Natural Killer Cell Status as a Prognostic Factor for Advanced Gastric Cancer

Natural killer cell-mediated immune surveillance in cancer: Role of tumor microenvironment

In the immunological surveillance against cancer, natural killer (NK) cells are essential effectors that help eradicate altered cells. The complex interactions that occur between NK cells and the tumor microenvironment (TME) are thoroughly examined in this review. The review examines how cytokine stimulation affects NK cell activation, focusing on the dynamic modulation of NK cell function within the TME. It looks at NK cell-related biomarkers such as PD-1/PD-L1, methylation HOXA9 (Homeobox A9), Stroma AReactive Invasion Front Areas (SARIFA), and NKG2A/HLA-E, providing critical information about prognosis and treatment outcomes. The changing landscape of immunotherapies-including checkpoint inhibitors, CAR-NK cells, and cytokine-based interventions-is examined in the context of enhancing NK cell activity. The review highlights the potential pathways for precision medicine going forward, focusing on customized immunotherapies based on unique biomarker profiles and investigating combination medicines to produce more robust anti-tumor responses.

Targeting MHC-I molecules for cancer: function, mechanism, and therapeutic prospects

The molecules of Major histocompatibility class I (MHC-I) load peptides and present them on the cell surface, which provided the immune system with the signal to detect and eliminate the infected or cancerous cells. In the context of cancer, owing to the crucial immune-regulatory roles played by MHC-I molecules, the abnormal modulation of MHC-I expression and function could be hijacked by tumor cells to escape the immune surveillance and attack, thereby promoting tumoral progression and impairing the efficacy of cancer immunotherapy. Here we reviewed and discussed the recent studies and discoveries related to the MHC-I molecules and their multidirectional functions in the development of cancer, mainly focusing on the interactions between MHC-I and the multiple participators in the tumor microenvironment and highlighting the significance of targeting MHC-I for optimizing the efficacy of cancer immunotherapy and a deeper understanding of the dynamic nature and functioning mechanism of MHC-I in cancer.

Prognostic impact of absolute peripheral blood NK cell count after four cycles of R-CHOP-like regimen treatment in patients with diffuse large B cell lymphoma

As a subtype of lymphocyte, natural killer (NK) cell is the first line of defense that shows a strong function in tumor immunotherapy response and clinical outcomes. The current study aims to investigate the prognostic influence of peripheral blood absolute NK cell count after four cycles of rituximab combined with cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) treatment (NKCC4) in diffuse large B cell lymphoma (DLBCL) patients. A total of 261 DLBCL patients treated with R-CHOP from January 2018 to September 2022 were enrolled. The low NKCC4 was observed in patients who died during the study period compared with survival individuals. A NKCC4 < 135 cells/μl had a remarkable negative influence in overall survival and progression-free survival (PFS) compared to a NKCC4 ≥ 135 cells/μl (p < 0.0001 and p < 0.0004, respectively). In addition, the OS and PFS were synergistically lower in a NKCC4 < 135 cells/μl group among DLBCL patients with GCB type or high IPI. In conclusion, this study indicates NCKK4 as a valuable marker in clinical practice and provides an insight for combination treatment of R-CHOP to improve outcomes of DLBCL patients.

Killer instincts: natural killer cells as multifactorial cancer immunotherapy

Natural killer (NK) cells integrate heterogeneous signals for activation and inhibition using germline-encoded receptors. These receptors are stochastically co-expressed, and their concurrent engagement and signaling can adjust the sensitivity of individual cells to putative targets. Against cancers, which mutate and evolve under therapeutic and immunologic pressure, the diversity for recognition provided by NK cells may be key to comprehensive cancer control. NK cells are already being trialled as adoptive cell therapy and targets for immunotherapeutic agents. However, strategies to leverage their naturally occurring diversity and agility have not yet been developed. In this review, we discuss the receptors and signaling pathways through which signals for activation or inhibition are generated in NK cells, focusing on their roles in cancer and potential as targets for immunotherapies. Finally, we consider the impacts of receptor co-expression and the potential to engage multiple pathways of NK cell reactivity to maximize the scope and strength of antitumor activities.

Monalizumab efficacy correlates with HLA-E surface expression and NK cell activity in head and neck squamous carcinoma cell lines

PURPOSE

NKG2A, an inhibitory receptor expressed on NK cells and T cells, leads to immune evasion by binding to HLA-E expressed on cancer cells. Here, we investigated the relationship between HLA-E surface expression on head and neck squamous cell carcinoma (HNSCC) cell lines and the efficacy of monalizumab, an NKG2A inhibitor, in promoting NK cell activity.

METHODS

Six HNSCC cell lines were used as target cells. After exposure to IFN- γ, HLA-E surface expression on HNSCC cell lines was measured by flow cytometry. Peripheral blood mononuclear cells (PBMCs) from healthy donors and isolated NK cells were used as effector cells. NK cells were stimulated by treatment with IL-2 and IL-15 for 5 days, and NK cell-induced cytotoxicity was analyzed by CD107a degranulation and 51Cr release assays.

RESULTS

We confirmed that HLA-E expression was increased by IFN-γ secreted by NK cells and that HLA-E expression was different for each cell line upon exposure to IFN-γ. Cell lines with high HLA-E expression showed stronger inhibition of NK cell cytotoxicity, and efficacy of monalizumab was high. Combination with cetuximab increased the efficacy of monalizumab. In addition, stimulation of isolated NK cells with IL-2 and IL-15 increased the efficacy of monalizumab, even in the HLA-E low groups.

CONCLUSION

Monalizumab efficacy was correlated with HLA-E surface expression and was enhanced when NK cell activity was increased by cetuximab or cytokines. These results suggest that monalizumab may be potent against HLA-E-positive tumors and that monalizumab efficacy could be improved by promoting NK cell activity.

Dynamic Alteration in HLA-E Expression and Soluble HLA-E via Interaction with Natural Killer Cells in Gastric Cancer

BACKGROUND

Some reports showed the immune tolerance of soluble human leukocyte antigen E (HLA-E), but the role that soluble HLA-E plays in gastric cancer (GC) is unknown. We aimed to clarify the molecular mechanism and clinical significance of soluble HLA-E in GC.

METHODS

We examined the expression of HLA-E on GC cells and soluble HLA-E under co-culture with natural killer (NK) cells in a time-dependent manner. Changes in NK cell activity were investigated using anti-NK group 2 member A (NKG2A) antibodies in the presence of soluble HLA-E. Expression of soluble HLA-E in the serum of GC patients was determined.

RESULTS

Whereas HLA-E expression on GC cells peaked with interferon (IFN)-γ secretion by NK cells in a time-dependent manner, soluble HLA-E was upregulated in conditioned medium. Pre-incubation with anti-NKG2A antibodies increased the activation of NKG2A⁺ NK cells in the presence of soluble HLA-E. Expression of soluble HLA-E in the serum of GC patients correlated with disease progression.

CONCLUSIONS

HLA-E expression dynamically changes on GC cells and in conditioned medium. Furthermore, soluble HLA-E can contribute to immune escape in GC cell lines, which may have significance in clinical practice. Moreover, soluble HLA-E may be a potential prognostic biomarker.

Disruption of the NKG2A:HLA-E Immune Checkpoint Axis to Enhance NK Cell Activation against Cancer

Ligation of the inhibitory receptor NKG2A by its ligand HLA-E negatively regulates the activation of natural killer (NK) cells, as well as subsets of CD8+ T cells and innate T cell populations. NKG2A has recently become a novel immune checkpoint target for the treatment of cancer and direct antibody mediated blockade of NKG2A function is currently under assessment in two phase 3 clinical trials. In addition to direct targeting, the NKG2A:HLA-E axis can also be disrupted indirectly via multiple different targeted cancer agents that were not previously recognised to possess immunomodulatory properties. Increased understanding of immune cell modulation by targeted cancer therapies will allow for the design of rational and more efficacious drug combination strategies to improve cancer patient outcomes. In this review, we summarise and discuss the various strategies currently in development which either directly or indirectly disrupt the NKG2A:HLA-E interaction to enhance NK cell activation against cancer.

alpha2,3 sialic acid processing enzymes expression in gastric cancer tissues reveals that ST3Gal3 but not Neu3 are associated with Lauren's classification, angiolymphatic invasion and histological grade

Gastric cancer (GC) is one of the leading causes of cancer-related deaths worldwide. Despite progress in the last decades, there are still no reliable biomarkers for the diagnosis of and prognosis for GC. Aberrant sialylation is a widespread critical event in the development of GC. Neuraminidases (Neu) and sialyltransferases (STs) regulate the ablation and addition of sialic acid during glycoconjugates biosynthesis, and they are a considerable source of biomarkers in various cancers. This study retrospectively characterized Neu3 and ST3Gal3 expression by immunohistochemistry in 71 paraffin-embedded GC tissue specimens and analyzed the relationship between their expression and the clinicopathological parameters. Neu3 expression was markedly increased in GC tissues compared with non-tumoral tissues (p<0.0001). Intratumoral ST3Gal3 staining was significantly associated with intestinal subtype (p=0.0042) and was negatively associated with angiolymphatic invasion (p=0.0002) and higher histological grade G3 (p=0.0066). Multivariate analysis revealed that ST3Gal3 positivity is able to predict Lauren's classification. No associations were found between Neu3 staining and clinical parameters. The in silico analysis of mRNA expression in GC validation cohorts corroborates the significant ST3Gal3 association with higher histological grade observed in our study. These findings suggest that ST3Gal3 expression may be an indicator for aggressiveness of primary GC.