p50 suppresses cytotoxic T lymphocyte effector function to regulate tumor immune escape and response to immunotherapy

NF-κB role on tumor proliferation, migration, invasion and immune escape

Nuclear factor kappa-B (NF-κB) is a nuclear transcription factor that plays a key factor in promoting inflammation, which can lead to the development of cancer in a long-lasting inflammatory environment. The activation of NF-κB is essential in the initial phases of tumor development and progression, occurring in both pre-malignant cells and cells in the microenvironment such as phagocytes, T cells, and B cells. In addition to stimulating angiogenesis, inhibiting apoptosis, and promoting the growth of tumor cells, NF-κB activation also causes the epithelial-mesenchymal transition, and tumor immune evasion. Therapeutic strategies that focus on immune checkpoint molecules have revolutionized cancer treatment by enabling the immune system to activate immunological responses against tumor cells. This review focused on understanding the NF-κB signaling pathway in the context of cancer.

Zinc-finger protein CXXC5 promotes breast carcinogenesis by regulating the TSC1/mTOR signaling pathway

CXXC5, a member of the CXXC family of zinc-finger proteins, is associated with numerous pathological processes. However, the pathophysiological function of CXXC5 has not been clearly established. Herein, we found that CXXC5 interacts with the CRL4B and NuRD complexes. Screening of transcriptional targets downstream of the CXXC5-CRL4B-NuRD complex by next-generation sequencing (chromatin immunoprecipitation sequencing) revealed that the complex regulates the transcriptional repression process of a cohort of genes, including TSC1 (tuberous sclerosis complex subunit 1), which play important roles in cell growth and mammalian target of rapamycin signaling pathway regulation, and whose abnormal regulation results in the activation of programmed cell death-ligand protein 1 (PD-L1). Intriguingly, CXXC5 expression increased after stimulation with vitamin B2 but decreased after vitamin D treatment. We also found that the CXXC5-CRL4B-NuRD complex promotes the proliferation of tumor cells in vitro and accelerates the growth of breast cancer in vivo. The expression of CXXC5, CUL4B, and MTA1 increased during the occurrence and development of breast cancer, and correspondingly, TSC1 expression decreased. Meanwhile, a high expression of CXXC5 was positively correlated with the histological grade of high malignancy and poor survival of patients. In conclusion, our study revealed that CXXC5-mediated TSC1 suppression activates the mammalian target of rapamycin pathway, reduces autophagic cell death, induces PD-L1-mediated immune suppression, and results in tumor development, shedding light on the mechanism of the pathophysiological function of CXXC5.

Construction of immunotherapy-related prognostic gene signature and small molecule drug prediction for cutaneous melanoma

Background

Cutaneous melanoma (CM), a kind of skin cancer with a high rate of advanced mortality, exhibits a wide variety of driver and transmitter gene alterations in the immunological tumor microenvironment (TME) associated with tumor cell survival and proliferation.

Methods

We analyzed the immunological infiltration of TME cells in normal and malignant tissues using 469 CM and 556 normal skin samples. We used a single sample gene set enrichment assay (ssGSEA) to quantify the relative abundance of 28 cells, then used the LASSO COX regression model to develop a riskScore prognostic model, followed by a small molecule drug screening and molecular docking validation, which was then validated using qRT-PCR and IHC.

Results

We developed a prognosis model around seven essential protective genes for the first time, dramatically elevated in tumor tissues, as did immune cell infiltration. Multivariate Cox regression results indicated that riskScore is an independent and robust prognostic indicator, and its predictive value in immunotherapy was verified. Additionally, we identified Gabapentin as a possible small molecule therapeutic for CM.

Conclusions

A riskScore model was developed in this work to analyze patient prognosis, TME cell infiltration features, and treatment responsiveness. The development of this model not only aids in predicting patient response to immunotherapy but also has significant implications for the development of novel immunotherapeutic agents and the promotion of tailored treatment regimens.

H3K9me3 represses G6PD expression to suppress the pentose phosphate pathway and ROS production to promote human mesothelioma growth

The role of glucose-6-phosphate dehydrogenase (G6PD) in human cancer is incompletely understood. In a metabolite screening, we observed that inhibition of H3K9 methylation suppressed aerobic glycolysis and enhances the PPP in human mesothelioma cells. Genome-wide screening identified G6PD as an H3K9me3 target gene whose expression is correlated with increased tumor cell apoptosis. Inhibition of aerobic glycolysis enzyme LDHA and G6PD had no significant effects on tumor cell survival. Ablation of G6PD had no significant effect on human mesothelioma and colon carcinoma xenograft growth in athymic mice. However, activation of G6PD with the G6PD-selective activator AG1 induced tumor cell death. AG1 increased tumor cell ROS production and the resultant extrinsic and intrinsic death pathways, mitochondrial processes, and unfolded protein response in tumor cells. Consistent with increased tumor cell death in vitro, AG1 suppressed human mesothelioma xenograft growth in a dose-dependent manner in vivo. Furthermore, AG1 treatment significantly increased tumor-bearing mouse survival in an intra-peritoneum xenograft athymic mouse model. Therefore, in human mesothelioma and colon carcinoma, G6PD is not essential for tumor growth. G6PD acts as a metabolic checkpoint to control metabolic flux towards the PPP to promote tumor cell apoptosis, and its expression is repressed by its promotor H3K9me3 deposition.

G6PD functions as a metabolic checkpoint to regulate granzyme B expression in tumor-specific cytotoxic T lymphocytes

Background

Granzyme B is a key effector of cytotoxic T lymphocytes (CTLs), and its expression level positively correlates with the response of patients with mesothelioma to immune checkpoint inhibitor immunotherapy. Whether metabolic pathways regulate Gzmb expression in CTLs is incompletely understood.

Methods

A tumor-specific CTL and tumor coculture model and a tumor-bearing mouse model were used to determine the role of glucose-6-phosphate dehydrogenase (G6PD) in CTL function and tumor immune evasion. A link between granzyme B expression and patient survival was analyzed in human patients with epithelioid mesothelioma.

Results

Mesothelioma cells alone are sufficient to activate tumor-specific CTLs and to enhance aerobic glycolysis to induce a PD-1^hi Gzmb^lo CTL phenotype. However, inhibition of lactate dehydrogenase A, the key enzyme of the aerobic glycolysis pathway, has no significant effect on tumor-induced CTL activation. Tumor cells induce H3K9me3 deposition at the promoter of G6pd, the gene that encodes the rate-limiting enzyme G6PD in the pentose phosphate pathway, to downregulate G6pd expression in tumor-specific CTLs. G6PD activation increases acetyl-coenzyme A (CoA) production to increase H3K9ac deposition at the Gzmb promoter and to increase Gzmb expression in tumor-specific CTLs converting them from a Gzmb^lo to a Gzmb^hi phenotype, thus increasing CTL tumor lytic activity. Activation of G6PD increases Gzmb⁺ tumor-specific CTLs and suppresses tumor growth in tumor-bearing mice. Consistent with these findings, GZMB expression level was found to correlate with increased survival in patients with epithelioid mesothelioma.

Conclusion

G6PD is a metabolic checkpoint in tumor-activated CTLs. The H3K9me3/G6PD/acetyl-CoA/H3K9ac/Gzmb pathway is particularly important in CTL activation and immune evasion in epithelioid mesothelioma.

Role of immune escape in different digestive tumours

A counterbalance between immune cells and tumour cells is key to fighting tumours, and immune escape is an important mechanism for the survival of tumour cells in the body. Tumor cells and their cytokines impair the activity of T cells, NK cells, macrophages and other immune cells through various ways, and change the expression of their own surface antigens so as to avoid the clearance of the immune system. Changes in major histocompatibility complex molecules, high expression of programmed death-ligand 1, and the presence of immunosuppressive cells in the tumor microenvironment (TME) are main means by which tumors impair the function of immune cells. During the development of tumours of the digestive system, different mechanisms acting on tumour cells, the TME, and immune cells lead to immune escape and promote tumour progression. In this paper, the mechanisms of immune escape in tumour cells of the digestive system are reviewed to provide a theoretical basis for the immunotherapy of gastrointestinal tumours.

Immune infiltration-related N6-methyladenosine RNA methylation regulators influence the malignancy and prognosis of endometrial cancer

N6-methyladenosine (m6A) RNA methylation is associated with malignant tumor progression and is modulated by various m6A RNA methylation regulator proteins. However, its role in endometrial cancer is unclear. In this work, we analyzed sequence, copy number variation, and clinical data obtained from the TCGA database. Expression was validated using real-time quantitative polymerase chain reaction and immunohistochemistry. Changes in m6A RNA methylation regulators were closely related to the clinicopathological stage and prognosis of endometrial cancer. In particular, ZC3H13, YTHDC1, and METTL14 were identified as potential markers for endometrial cancer diagnosis and prognosis. The TIMER algorithm indicated that immune cell infiltration correlated with changes in ZC3H13, YTHDC1, and METTL14 expression. Meanwhile, ZC3H13 or YTHDC1 knockdown promoted the proliferation and invasion of endometrial cancer cells. Through gene enrichment analysis, we constructed a regulatory network in order to explore the potential molecular mechanism involving ZC3H13, YTHDC1, and METTL14. Virtual screening predicted interactions of potential therapeutic compounds with METTL14 and YTHDC1. These findings advance the understanding of RNA epigenetic modifications in endometrial cancer while identifying m6A regulators associated with immune infiltration, prognosis, and potential treatment strategies.

NF-κB in Cancer Immunity: Friend or Foe?

The emergence of immunotherapies has definitely proven the tight relationship between malignant and immune cells, its impact on cancer outcome and its therapeutic potential. In this context, it is undoubtedly critical to decipher the transcriptional regulation of these complex interactions. Following early observations demonstrating the roles of NF-κB in cancer initiation and progression, a series of studies converge to establish NF-κB as a master regulator of immune responses to cancer. Importantly, NF-κB is a family of transcriptional activators and repressors that can act at different stages of cancer immunity. In this review, we provide an overview of the selective cell-intrinsic contributions of NF-κB to the distinct cell types that compose the tumor immune environment. We also propose a new view of NF-κB targeting drugs as a new class of immunotherapies for cancer.

MS4A1 expression and function in T cells in the colorectal cancer tumor microenvironment

The majority of human colorectal cancer remains resistant to immune checkpoint inhibitor (ICI) immunotherapy, but the underlying mechanism is incompletely understood. We report here that MS4A1, the gene encoding B cell surface marker CD20, is significantly downregulated in human colorectal carcinoma. Furthermore, MS4A1 expression level in colorectal carcinoma is positively correlated with patient survival. Analysis of scRNA-Seq dataset from public database revealed that MS4A1 is also expressed in subsets of T cells. A CD8⁺CD20⁺ subset of T cells exists in the neighboring non-neoplastic colon but disappears in tumor in human colorectal carcinoma. Furthermore, analysis of a published nivolumab treatment dataset indicated that nivolumab-bound T cells from human patients during anti-PD-1 immunotherapy exhibit significantly higher MS4A1 expression. Our findings indicate that CD8⁺CD20⁺ T subset functions in host cancer immunosurveillance and tumor microenvironment suppresses this T subset through a PD-L1-dependent mechanism.