Immune Escape Of Cancer Cells Research Articles

PD-L2 of tumor-derived exosomes mediates the immune escape of cancer cells via the impaired T cell function

The function of PD-1/PD-L1 axis have been intensively studied for immune escape of various cancers. However, the underlying function of PD-L2 remains poorly understood. Here, we demonstrate that PD-L2 is majorly expressed in exosomes with surface localization by clear cell renal cell carcinoma (ccRCC) cells. Tumor cell-derived exosome PD-L2 (TDE-PD-L2) exhibits high expression compared with TDE-PD-L1 in various cancers. In the absence of adaptive immune, TDE-PD-L2 suppresses tumor growth and metastasis. Under immune competence condition, TDE-PD-L2 is hijacked by immune cells in a PD-1-dependent manner to systematically dampen function of T cells via the increased proportion of the regulatory T cells and the decreased proportion of cytotoxic CD8+ T cells in both tumor-infiltrating T cells and spleen. The effects of TDE-PD-L2 on tumor is restored by antibodies targeting PD-L2. Collectively, we demonstrate that PD-1/TDE-PD-L2 axis systematically suppresses T cell functions, representing a potentially therapeutic strategy for ccRCC treatment.

CXCR4 up-regulation mediated by USP1 deubiquitination promotes the tumorigenesis and immune escape in esophageal squamous-cell carcinoma.

CXC chemokine receptor 4 (CXCR4) and ubiquitin specific protease 1 (USP1) have been reported to involve in the tumorigenesis of esophageal squamous-cell carcinoma (ESCC). Here, we investigated whether USP1 induced CXCR4 deubiquitination in regulating ESCC progression. MTT assay, 5-ethynyl-2'-deoxyuridine assay, flow cytometry, transwell assay and ELISA analysis were used to detect cell oncogenic phenotypes, macrophage phenotypes, inflammatory cytokines production, the cytotoxicity of cytokine-induced killer (CIK) cells and CD8 + T cell apoptosis. Protein interaction was determined by immunoprecipitation assay. Cellular ubiquitination detected the ubiquitination effect on CXCR4. A mouse xenograft model was established for in vivo experiments. CXCR4 was highly expressed in ESCC tissues and cells. Functionally, CXCR4 silencing suppressed ESCC cell proliferation, invasion, and induced cell apoptosis. Moreover, CXCR4 deficiency suppressed cancer cell immune escape by suppressing macrophage M2 polarization, elevating inflammatory cytokines produced by PBMCs, enhancing the cytotoxicity of CIK cells, and suppressing CD8 + T cell apoptosis. A high USP1 expression was observed in ESCC, USP1 interacted with CXCR4 and enhanced its protein stability through deubiquitination. USP1 silencing suppressed ESCC cell proliferation, invasion, and immune escape, which were reversed by CXCR4 overexpression. In vivo assay showed that USP1 deficiency impeded tumor growth by regulating CXCR4. Besides, fused in sarcoma (FUS) was confirmed to bind to USP1 and stabilized its mRNA expression, and could regulate CXCR4 via USP1. In conclusion, USP1 stabilized CXCR4 by removing ubiquitination on CXCR4, thereby promoting ESCC cell proliferation, invasion, and immune escape in vitro, and tumor growth in vivo.

Tumor-on-chip platforms for breast cancer continuum concept modeling.

Our previous article entitled "Proteomics and its applications in breast cancer", proposed a Breast Cancer Continuum Concept (BCCC), including a Breast Cancer Cell Continuum Concept as well as a Breast Cancer Proteomic Continuum Concept. Breast cancer-on-chip (BCoC), breast cancer liquid biopsy-on-chip (BCLBoC), and breast cancer metastasis-on-chip (BCMoC) models successfully recapitulate and reproduce in vitro the principal mechanisms and events involved in BCCC. Thus, BCoC, BCLBoC, and BCMoC platforms allow for multiple cell lines co-cultivation to reproduce BC hallmark features, recapitulating cell proliferation, cell-to-cell communication, BC cell-stromal crosstalk and stromal activation, effects of local microenvironmental conditions on BC progression, invasion/epithelial-mesenchymal transition (EMT)/migration, intravasation, dissemination through blood and lymphatic circulation, extravasation, distant tissues colonization, and immune escape of cancer cells. Moreover, tumor-on-chip platforms are used for studying the efficacy and toxicity of chemotherapeutic drugs/nano-drugs or nutraceuticals. Therefore, the aim of this review is to summarize and analyse the main bio-medical roles of on-chip platforms that can be used as powerful tools to study the metastatic cascade in BC. As future direction, integration of tumor-on-chip platforms and proteomics-based specific approaches can offer important cues about molecular profile of the metastatic cascade, alowing for novel biomarker discovery. Novel microfluidics-based platforms integrating specific proteomic landscape of human milk, urine, and saliva could be useful for early and non-invasive BC detection. Also, risk-on-chip models may improve BC risk assessment and prevention based on the identification of biomarkers of risk. Moreover, multi-organ-on-chip systems integrating patient-derived BC cells and patient-derived scaffolds have a great potential to study BC at integrative level, due to the systemic nature of BC, for personalized and precision medicine. We also emphasized the strengths and weaknesses of BCoC and BCMoC platforms.

NFKB2 mediates colorectal cancer cell immune escape and metastasis in a STAT2/PD‐L1‐dependent manner

This study systematically analyzed the molecular mechanism and function of nuclear factor kappa B subunit 2 (NFKB2) in colorectal cancer (CRC) to investigate the potential of NFKB2 as a therapeutic target for CRC. Various experimental techniques, including RNA sequencing, proteome chip assays, and small molecule analysis, were used to obtain a deeper understanding of the regulation of NFKB2 in CRC. The results revealed that NFKB2 was upregulated in a significant proportion of patients with advanced hepatic metastasis of CRC. NFKB2 played an important role in promoting tumor growth through CD8+ T-cell exhaustion. Moreover, NFKB2 directly interacted with signal transducer and activator of transcription 2 (STAT2), leading to increased phosphorylation of STAT2 and the upregulation of programmed death ligand 1 (PD-L1). Applying a small molecule inhibitor of NFKB2 (Rg5) led to a reduction in PD-L1 expression and improved response to programmed death-1 blockade-based immunotherapy. In conclusion, the facilitated NFKB2-STAT2/PD-L1 axis may suppress immune surveillance in CRC and targeting NFKB2 may enhance the efficacy of immunotherapeutic strategies. Our results provide novel insights into the molecular mechanisms underlying the contribution of NFKB2 in CRC immune escape.

Programmed cell death-ligand 2: new insights in cancer.

Immunotherapy has revolutionized cancer treatment, with the anti-PD-1/PD-L1 axis therapy demonstrating significant clinical efficacy across various tumor types. However, it should be noted that this therapy is not universally effective for all PD-L1-positive patients, highlighting the need to expedite research on the second ligand of PD-1, known as Programmed Cell Death Receptor Ligand 2 (PD-L2). As an immune checkpoint molecule, PD-L2 was reported to be associated with patient's prognosis and plays a pivotal role in cancer cell immune escape. An in-depth understanding of the regulatory process of PD-L2 expression may stratify patients to benefit from anti-PD-1 immunotherapy. Our review focuses on exploring PD-L2 expression in different tumors, its correlation with prognosis, regulatory factors, and the interplay between PD-L2 and tumor treatment, which may provide a notable avenue in developing immune combination therapy and improving the clinical efficacy of anti-PD-1 therapies.

Low-density lipoprotein receptor-related protein 5/6 promotes endometrial cancer progression and cancer cell immune escape.

The study investigated the potential association of the low-density lipoprotein (LDL) genome with endometrial cancer progression based on the Gene Expression Omnibus data set and The Cancer Genome Atlas data set. Differential and weighted gene coexpression network analysis was performed on endometrial cancer transcriptome datasets GSE9750 and GSE106191. The protein-protein interaction network was built using LDL-receptor proteins and the top 50 tumor-associated genes. Low-density lipoprotein-related receptors 5/6 (LRP5/6) in endometrial cancer tissues were correlated with oncogenes, cell cycle-related genes, and immunological checkpoints using Spearman correlation. MethPrimer predicted the LRP5/6 promoter CpG island. LRP2, LRP6, LRP8, LRP12, low-density lipoprotein receptor-related protein-associated protein, and LRP5 were major LDL-receptor-related genes associated with endometrial cancer. LRP5/6 was enriched in various cancer-related pathways and may be a key LDL-receptor-related gene in cancer progression. LRP5/6 may be involved in the proliferation process of endometrial cancer cells by promoting the expression of cell cycle-related genes. LRP5/6 may be involved in the proliferation of endometrial cancer cells by promoting the expression of cell cycle-related genes. LRP5/6 may promote the immune escape of cancer cells by promoting the expression of immune checkpoints, promoting endometrial cancer progression. The MethPrimer database predicted that the LRP5/6 promoter region contained many CpG islands, suggesting that DNA methylation can occur in the LRP5/6 promoter region. LRP5/6 may aggravate endometrial cancer by activating the phosphoinositide 3-kinase/protein kinase B pathway.

Long non-coding RNAs in cancer: multifaceted roles and potential targets for immunotherapy.

Cancer remains a major global health concern with high mortality rates mainly due to late diagnosis and poor prognosis. Long non-coding RNAs (lncRNAs) are emerging as key regulators of gene expression in human cancer, functioning through various mechanisms including as competing endogenous RNAs (ceRNAs) and indirectly regulating miRNA expression. LncRNAs have been found to have both oncogenic and tumor-suppressive roles in cancer, with the former promoting cancer cell proliferation, migration, invasion, and poor prognosis. Recent research has shown that lncRNAs are expressed in various immune cells and are involved in cancer cell immune escape and the modulation of the tumor microenvironment, thus highlighting their potential as targets for cancer immunotherapy. Targeting lncRNAs in cancer or immune cells could enhance the anti-tumor immune response and improve cancer immunotherapy outcomes. However, further research is required to fully understand the functional roles of lncRNAs in cancer and the immune system and their potential as targets for cancer immunotherapy. This review offers a comprehensive examination of the multifaceted roles of lncRNAs in human cancers, with a focus on their potential as targets for cancer immunotherapy. By exploring the intricate mechanisms underlying lncRNA-mediated regulation of cancer cell proliferation, invasion, and immune evasion, we provide insights into the diverse therapeutic applications of these molecules.

IL-32 production from lung adenocarcinoma cells is potentially involved in immunosuppressive microenvironment.

Interleukin 32 (IL-32) is a proinflammatory cytokine secreted from several kinds of cancer cells. In the present study, we investigated the significance of IL-32 in lung adenocarcinoma by immunohistochemistry and bioinformatics analysis. IL-32 was positive in cancer cells of 21 cases (9.2%) of total 228 cases. Increased IL-32 gene expression was linked to worse clinical course in TCGA analysis, however, IL-32 expression in immunohistochemistry was not associated to clinical course in our cohort. It was also found that high IL-32 expression was seen in cases with increased lymphocyte infiltration. In vitro studies indicated that IFN-γ induced gene expression of IL-32 and PD1-ligands in lung adenocarcinoma cell lines. IL-32, especially IL-32β, also induced overexpression of PD1-ligands in human monocyte-derived macrophages. Additionally, Cancer-cell-derived IL-32 was elevated by stimulation with anticancer agents. In conclusion, IL-32 potentially induced by inflammatory conditions and anticancer therapy and contribute to immune escape of cancer cells via development the immunosuppressive microenvironment. IL-32 might be a target molecule for anti-cancer therapy.

Bone Marrow Microenvironment-Responsive Nanomedicine Promotes Anti-Leukemia Activity In Vivo

Background: Leukemia escape and relapse is the leading cause of death after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia (AML). Work over the past decades has demonstrated that the CD47- signal-regulatory protein α (SIRPa) interaction mediated cancer cell immune escape. Although CD47-SIRPα interaction blockade contributes to cancer cell clearance by macrophages, how to deliver the anti-CD47 to bone marrow niche through an efficient drug delivery strategy and improve the cytotoxic activity of macrophages is an important issue that needs to be addressed. Methods: Here, we performed immunohistochemical (IHC) analysis and flow cytometry analysis of TIM-3 expression using samples of bone marrow from patients with or without relapse. In addition, according to the natural “myeloid niche homing” characteristic of AML cells and the low-oxygen microenvironment in bone marrow, we constructed β-cyclodextrin azobenzene linker (AZO-β-CD)-modified fusion protein and amantadine-modified HSA protein (HSA-ADA), followed by the addition of anti-CD47. Furthermore, the nanogel TIM3-targeting antibodies were modified on the surface of the nanogel to finally construct the supramolecular nanogel delivery system. Moreover, we detected the effect of target nanomedicine in a leukemia xenograft mouse model. Results: We demonstrated that in the bone marrow microenvironment of patients with relapse, the expression of TIM-3 significantly increased, especially in the CD34 +CD38 + leukemic progenitors, but not in the HSCs. Furthermore, we verified using nanomedicine could significantly increase the number of macrophages in the bone marrow. Importantly, the blockade of CD47-SIRPα signaling using nanomedicine markedly improved the anti-tumor activity in a leukemia xenograft mouse model. Conclusion: Thus, our findings reveal that nanomedicine could inhibit CD47-SIRPα signaling and contribute to anti-leukemia function effectively, which may be a new strategy for preventing and treating the recurrence of AML after transplantation.

Data Mining Suggests That CXCL14 Gene Silencing in Colon Cancer Is Due to Promoter Methylation.

CXCL14 is one of the most evolutionarily conserved members of the chemokine family and is constitutionally expressed in multiple organs, suggesting that it is involved in the homeostasis maintenance of the system. CXCL14 is highly expressed in colon epithelial cells and shows obvious gene silencing in clinical colon cancer samples, suggesting that its silencing is related to the immune escape of cancer cells. In this paper, we analyzed the expression profiles of multiple human clinical colon cancer datasets and mouse colon cancer models to reveal the variation trend of CXCL14 expression during colitis, colon polyps, primary colon cancer, and liver metastases. The relationship between CXCL14 gene silencing and promoter hypermethylation was revealed through the colorectal carcinoma methylation database. The results suggest that CXCL14 is a tumor suppressor gene in colorectal carcinoma which is activated first and then silenced during the process of tumor occurrence and deterioration. Promoter hypermethylation is the main cause of CXCL14 silencing. The methylation level of CXCL14 is correlated with the anatomic site of tumor occurrence, positively correlated with patient age, and associated with prognosis. Reversing the hypermethylation of CXCL14 may be an epigenetic therapy for colon cancer.

In Situ Capturing and Counting Device for the Specific Depletion and Purification of Cancer-Derived Exosomes.

From metabolic waste to biological mediators, exosomes have emerged as the key player in a variety of pathological processes, particularly in oncogenesis. The exosome-mediated communication network involves nearly every step of cancer progression, promoting the proliferation and immune escape of cancer cells. Therefore, the removal of cancer-derived exosomes has profound clinical significance. Current methods for exosome separation and enrichment are either for large-scale samples or require complex pretreatment processes, lacking effective methods for trace-volume exosome capture in situ. Herein, we have developed an in situ exosome capturing and counting device based on the antibody-functionalized capillary. Specific antibodies targeting exosome biomarkers were immobilized to the inner wall of the capillary via biotin-streptavidin interaction for direct cancer exosome capturing. Subsequent exosome staining enabled imaging and enumeration. Acceptable linearity and reproducibility were achieved with our device, with the capturing and detective range between 3.3 × 104 and 3.3 × 108 particles, surpassing the nanoparticle tracking analysis by 2 orders of magnitude while requiring merely 30 μL sample. We demonstrated that MCF-7-derived exosomes induced epithelial-mesenchymal transition of epithelial cells MCF-10A, and our method was able to completely or partially reverse the transition by complete depletion or specific depletion of cancer exosomes without any preprocessing. Moreover, both whole exosomes and cancer-specific exosomes alone from mimic blood samples were successfully captured and counted, without obvious non-specific adsorption. In all, our approach realized the in situ depletion and number-counting of cancer-derived exosomes directly from the complex humoral environment, having the potential to provide a comprehensive tumor therapeutic and prognosis evaluation tool by targeted hemodialysis and counting of tumor-derived exosomes.

Marsdenia tenacissima enhances immune response of tumor infiltrating T lymphocytes to colorectal cancer.

Tumor-infiltrating T lymphocytes in the tumor microenvironment are critical factors influencing the prognosis and chemotherapy outcomes. As a Chinese herbal medicine, Marsdenia tenacissima extract (MTE) has been widely used to treat cancer in China. Its immunoregulatory effects on tumor-associated macrophages is well known, but whether it regulates tumor-infiltrating T-cell functions remains unclear. We collected 17 tumor samples from MTE-administered colorectal cancer patients, 13 of which showed upregulation of CD3+/CD8+ tumor-infiltrating T cells. Further in vitro and in vivo experiments were performed to investigate the regulatory effects of MTE on tumor-infiltrating T cells and immune escape of tumors. Under single and co-culture conditions, MTE inhibited TGF-β1 and PD-L1 expression in the colorectal cancer (CRC) cell lines HCT116 and LoVo. In Jurkat cells, MTE inhibited FOXP3 and IL-10 expression, increased IL-2 expression, but had no effect on PD-1 expression. These findings were confirmed in vitro using subcutaneous and colitis-associated CRC mouse models. MTE also increased the density of CD3+/CD8+ tumor-infiltrating T cells and exhibited considerable tumor-suppressive effects in these two tumor mouse models. Our findings suggested that MTE inhibits the immune escape of cancer cells, a precipitating factor increasing the immune response of T lymphocytes.

Thyroid dysfunction and immune checkpoint inhibitors: Effect on survival in elderly patients.

e24020 Background: Aging inevitably leads to an accumulation of senescent cells, and immune system cells aren't an exception. They can contribute to a pro-inflammatory state and be involved in the immune escape of cancer cells through a boosted PD-L1 expression. Immunocheckpoint inhibitors (ICIs) represent the standard of care in several cancer histotypes, and immune-related adverse events (irAEs) seem to be associated with better outcomes. ICIs represent a valid therapeutic agent in elderly patients too. However, there is a lack of data on irAEs and outcomes correlation in this subgroup of patients. This retrospective-prospective study aims to evaluate the relationship between thyroid dysfunction and progression-free survival (PFS) and overall survival (OS) in elderly patients undergoing ICIs. Methods: From January 2019 to January 2023, we retrospectively collected data from 65 elderly patients under treatment with ICIs at the Medical Oncology Unit of the University Hospital and University of Cagliari, Italy. All patients were affected by stage IV disease. The primary endpoint was PFS and the secondary endpoint was overall survival OS. Statistical analyses were performed using the MedCalc Statistical Software Version 20.216. Results: The median age was 76 (± 5,5); 15.38% were female, whereas 84.62% were male. The histologies were: melanoma (26.9%), lung cancer (48.0%), kidney cancer (15.3%), and colorectal cancer (9.8%). Compared to those without thyroid dysfunction during immunotherapy treatment, individuals with thyroid irAE had, at univariate analysis, longer median PFS (68 versus 26 months, p = 0.02, CI 95% 18.0-68.0, HR 0.29 0.10-0.83) and longer median OS (59 versus 39 months, p = 0.04, CI 95% 25.0-90.0 HR 0.50 0.25-0.99). Conclusions: In an era where biomarkers for immunotherapeutic agents are lacking, thyroid dysfunction irAE could be a predictive factor of better PFS and OS in elderly patients affected by cancer of various histology.

PD-L1 stimulation can promote proliferation and survival of leukemic cells by influencing glucose and fatty acid metabolism in acute myeloid leukemia

BackgroundLeukemic cell metabolism plays significant roles in their proliferation and survival. These metabolic adaptations are under regulation by different factors. Programmed Death Ligand -1 (CD-274) is one of the immune checkpoint ligands that do not only cause the immune escape of cancer cells, but also have some intracellular effects in these cells. PD-L1 is overexpressed on leukemic stem cells and relates with poor prognosis of AML. In this study, we investigated effects of PD-L1 stimulation on critical metabolic pathways of glucose and fatty acid metabolisms that have important roles in proliferation and survival of leukemic cells.MethodsAfter confirmation of PD-L1 expression by flow cytometry assay, we used recombinant protein PD-1 for stimulation of the PD-L1 on two AML cell lines, HL-60 and THP-1. Then we examined the effect of PD-L1 stimulation on glucose and fatty acid metabolism in cells at the genomic and metabolomic levels in a time dependent manner. We investigated expression changes of rate limiting enzymes of theses metabolic pathways (G6PD, HK-2, CPT1A, ATGL1 and ACC1) by qRT-PCR and also the relative abundance changes of free fatty acids of medium by GC.ResultsWe identified a correlation between PD-L1 stimulation and both fatty acid and glucose metabolism. The PD-L1 stimulated cells showed an influence in the pentose phosphate pathway and glycolysis by increasing expression of G6PD and HK-2 (P value = 0.0001). Furthermore, PD-L1 promoted fatty acid β-oxidation by increasing expression of CPT1A (P value = 0.0001), however, their fatty acid synthesis was decreased by reduction of ACC1 expression (P value = 0.0001).ConclusionWe found that PD-L1 can promote proliferation and survival of AML stem cells probably through some metabolic changes in leukemic cells. Pentose phosphate pathway that has a critical role in cell proliferation and fatty acids β-oxidation that promote cell survival, both are increased by PD-L1 stimulation on AML cells.

PPARγ inhibited tumor immune escape by inducing PD-L1 autophagic degradation.

Blockade of the programmed death 1 (PD-1)/ programmed death ligand 1 (PD-L1) immune checkpoint could increase antitumor immunotherapy for multiple types of cancer, but the response rate of patients is about 10%-40%. Peroxisome proliferator activated receptor γ (PPARγ) plays an important role in regulating cell metabolism, inflammation, immunity, and cancer progression, while the mechanism of PPARγ on cancer cell immune escape is still unclear. Here we found that PPARγ expression exhibits a positive correlation with activation of T cells in non-small-cell lung cancer (NSCLC) by clinical analysis. Deficiency of PPARγ promoted immune escape of NSCLC by inhibiting T-cell activity, which was associated with increased PD-L1 protein level. Further analysis showed that PPARγ reduced PD-L1 expression independent of its transcriptional activity. PPARγ contains the microtubule-associated protein 1A/1B-light chain 3 (LC3) interacting region motif, which acts as an autophagy receptor for PPARγ binding to LC3, leading to degradation of PD-L1 in lysosomes, which in turn suppresses NSCLC tumor growth by increasing T-cell activity. These findings suggest that PPARγ inhibits the tumor immune escape of NSCLC by inducing PD-L1 autophagic degradation.

Abstract 5869: The concordant disruption of B7/CD28 immune regulators predicts the prognosis of oral carcinoma

Abstract Immune-escape is a critical factor determining the survival of malignancies including oral squamous cell carcinoma (OSCC). The immune escape of cancer cells may be driven by B7/CD28 family members and others on the tumor cells that form ligand-inhibitory receptor complexes with immune cells. Since the family members of B7/CD28 can functionally compensate, the concomitant disruption of multiple B7/CD28 family members in OSCC pathogenesis remains elusive. RNAseq performed on OSCC and paired oral mucosa retrieved the transcriptome of OSCC, and algorithms signified the general alterations of T cell population and the increase of macrophage population in tumors relative to controls. Upregulation of CD80, CD86, PD-L1, PD-L2, CD276 and CTLA4, and downregulation of L-ICOS in OSCC relative to normal mucosa was noted. In addition, there was a high concordance in the expression profile across the dysregulated regulators. The co-upregulation of CD276 and CTLA4 was associated with the decrease of T helper and NK cell population, and the increase of Treg and myeloid dendritic cell population. Interestingly, tumors harboring higher PD-L1 and/or PD-L2 expression accompany with lower ICOS or PD1 expression exhibited worse prognosis. In combination with these immunity features in primary tumors, the survival of patients with lymph node metastasis was further worsened. In the isografic models of murine OSCC cell lines, the decrease of CD4+T population in the lymph node and increase of myeloid dendritic cell population in the spleen were induced in the host mice. Many miRNAs are involved in the modulation of immune escape for malignancies. With the treatment of inhibitors against oncogenic miRNAs which enabled the OSCC suppression, the inhibitors of miR-146a and miR-211 also resulted in the down-regulation in the protein expression of multiple B7/CD28 members. This study concludes the eminent co-disruption of B7/CD28 members in OSCC tumors, which would confound the patient survival. The efficacy of miRNA inhibitors in abrogating oncogenicity and B7/CD28 members could be a therapeutic strategy. Citation Format: Sih-Rou Chang. The concordant disruption of B7/CD28 immune regulators predicts the prognosis of oral carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5869.

HLA and tumour immunology: immune escape, immunotherapy and immune-related adverse events.

As molecules responsible for presenting antigens to T lymphocytes, leukocytes antigens (HLAs) play a vital role in cancer immunology. This review aims to provide current understanding of HLAs in tumour immunology. Perspectives on how HLA alterations may contribute to the immune escape of cancer cells and resistance to immunotherapy, and potential methods to overcome HLA defects were summarized. In addition, we discussed the potential association between HLA and immune-related adverse events (irAEs), which has not been reviewed elsewhere. Downregulation, loss of heterogeneity and entire loss of HLAs are responsible for the immune escape of tumour cells. The strategies to overcome the HLA defects can be effective therapies of cancer. Compared with classical HLA-I, non-classical HLA-I molecules, such as HLA-E and HLA-G, appear to be more reliable predictors of prognosis, as they tend to play immunosuppressive roles in antitumor response. Relative diversified or high expression of classical HLA-I are potential predictors of favourable response of immunotherapy. Certain HLA types may be associated to enhanced affinity to self-antigen-mimicked tumour-antigens, thus may positively correlated to irAEs triggered by checkpoint inhibitors. Further studies exploring the relationship between HLAs and cancer may not only lead to the development of novel therapies but also bring about better management of irAEs.

Extracellular vesicles derived from M2-polarized tumor-associated macrophages promote immune escape in ovarian cancer through NEAT1/miR-101-3p/ZEB1/PD-L1 axis.

Evidence has been presented demonstrating that CD8+ T cells confer anti-cancer effects, which offers a promising approach to enhance immunotherapy. M2-polarized tumor-associated macrophages (TAMs) could transfer RNA to cancer cells by secreting extracellular vesicles (EVs) and stimulate immune escape of cancer cells. Thus, the current study aimed at exploring how EVs derived from M2-polarized TAMs (M2-TAMs) affected the proliferation of ovarian cancer (OC) cells and apoptosis of CD8+ T cells. M2-TAMs were observed in OC tissues, which promoted proliferation of OC cells and CD8+ T cell apoptosis by secreting EVs. OC-associated differentially expressed gene NEAT1 was screened by bioinformatics analysis. The in vitro and in vivo effects of TAM-EVs-NEAT1 and its regulatory mechanism were assessed using gain- and loss-of-function assays in co-culture systems of TAMs-derived EVs, OC cells, and CD8+ T cells and in tumor-bearing mice. NEAT1 was highly expressed in M2-derived EVs and OC cells co-cultured with M2-derived EVs. NEAT1 sponged miR-101-3p to increase ZEB1 and PD-L1 expression. In vitro and in vivo assays confirmed the tumor-supporting effects of NEAT1 delivered by M2-derived EVs on OC cell proliferation and CD8+ T cell apoptosis as well as tumor growth. Collectively, M2-derived EVs containing NEAT1 exerted a tumor-promoting role in OC via the miR-101-3p/ZEB1/PD-L1 axis.

Docosahexaenoic acid reverses PD-L1-mediated immune suppression by accelerating its ubiquitin-proteasome degradation

PD-L1 interacts with its receptor PD-1 on T cells to negatively regulate T cell function, leading to cancer cell immune escape from the immune surveillance. Therefore, targeting PD-L1 is considered to be an attractive approach for cancer immunotherapy. In this study, we demonstrated for the first time that ω-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) reduced the expression of PD-L1 in cancer cells both in vitro and in vivo. Promotion of PD-L1 ubiquitin-proteasome degradation by DHA resulted in a decrease of PD-L1 expression, leading to reduction of PD-L1 and PD-1 interaction, and reversing PD-L1-mediated immune suppression, which in turn contributed to the inhibitory effect on tumor growth. Furtherly, DHA significantly reduced fatty acid synthase (FASN) expression in cancer cells, which inhibited the palmitoyltransferases DHHC5, promoting the CSN5-dependent PD-L1 degradation. Our present finding uncovered a novel mechanism involved in the anti-cancer activity of DHA, and implicated that DHA holds promising potential to be developed as a novel immune-enhancer for cancer treatment and prevention.

Preclinical Evaluation of CRISPR-Edited CAR-NK-92 Cells for Off-the-Shelf Treatment of AML and B-ALL.

Acute myeloid leukemia (AML) and B-cell acute lymphocytic leukemia (B-ALL) are severe blood malignancies affecting both adults and children. Chimeric antigen receptor (CAR)-based immunotherapies have proven highly efficacious in the treatment of leukemia. However, the challenge of the immune escape of cancer cells remains. The development of more affordable and ready-to-use therapies is essential in view of the costly and time-consuming preparation of primary cell-based treatments. In order to promote the antitumor function against AML and B-ALL, we transduced NK-92 cells with CD276-CAR or CD19-CAR constructs. We also attempted to enhance cytotoxicity by a gene knockout of three different inhibitory checkpoints in NK cell function (CBLB, NKG2A, TIGIT) with CRISPR-Cas9 technology. The antileukemic activity of the generated cell lines was tested with calcein and luciferase-based cytotoxicity assays in various leukemia cell lines. Both CAR-NK-92 exhibited targeted cytotoxicity and a significant boost in antileukemic function in comparison to parental NK-92. CRISPR-Cas9 knock-outs did not improve B-ALL cytotoxicity. However, triple knock-out CD276-CAR-NK-92 cells, as well as CBLB or TIGIT knock-out NK-92 cells, showed significantly enhanced cytotoxicity against U-937 or U-937 CD19/tag AML cell lines. These results indicate that the CD19-CAR and CD276-CAR-NK-92 cell lines' cytotoxic performance is suitable for leukemia killing, making them promising off-the-shelf therapeutic candidates. The knock-out of CBLB and TIGIT in NK-92 and CD276-CAR-NK-92 should be further investigated for the treatment of AML.