Very long chain fatty acid beta-oxidation by rat liver mitochondria and peroxisomes

Peptide-MHC I regulatory mechanisms and intervention strategies in anti-tumor T cell immunity

T cell immune responses are triggered by antigenic peptides presented through major histocompatibility complex class Is (pMHC-Is), which play an important role in the genesis, development, and therapy of tumors. The capacity of a specific pMHC-I to elicit T cell responses is deeply influenced by its expression level (quantity) and its immunogenicity (quality). Tumor cells can evade T cell immunity by down-regulating the quantity of pMHC-Is or selectively eliminating highly immunogenic antigenic peptides. Augmenting the quantity or quality of pMHC-Is is essential for tumor immunotherapy. However, the complexity of pMHC-I regulation and tumor heterogeneity pose challenges to clinical strategies. Consequently, developing approaches grounded in comprehensive analyses of pMHC-I regulatory mechanisms remains a focal point in the research of T cell immunity. In this review, we discuss how tumors modulate their surface pMHC-Is through genetic, epigenetic, and proteomic mechanisms and summarize potential therapeutic strategies targeting these mechanisms, which may provide a valuable reference for the development of novel tumor immunotherapies based on pMHC-I modulation. Tumor cells can achieve immune escape by interfering with the quantity and quality of pMHC-Is, and corresponding immunotherapy can also be achieved by the regulation of pMHC-Is.

Revolutionary Cancer Therapy for Personalization and Improved Efficacy: Strategies to Overcome Resistance to Immune Checkpoint Inhibitor Therapy

Cancer remains a significant public health issue worldwide, standing as a primary contributor to global mortality, accounting for approximately 10 million fatalities in 2020 [...].

Tumor antigen presentation and the associated signal transduction during carcinogenesis

Numerous developments have been achieved in the study and treatment of cancer throughout the decades that it has been common. After decades of research, about 100 different kinds of cancer have been found, each with unique subgroups within certain organs. This has significantly expanded our understanding of the illness. A mix of genetic, environmental, and behavioral variables contribute to the complicated and diverse process of cancer formation. Mutations, or changes in the DNA sequence, are crucial to the development of cancer. These mutations have the ability to downregulate the expression and function of Major Histocompatibility Complex class I (MHC I) and MHCII receptors, as well as activate oncogenes and inactivate tumor suppressor genes. Cancer cells use this tactic to avoid being recognized by cytotoxic CD8+T lymphocytes, which causes issues with antigen presentation and processing. This review goes into great length into the PI3K pathway, changes to MHC I, and positive impacts of tsMHC-II on disease-free survival and overall survival and the involvement of dendritic cells (DCs) in different tumor microenvironments. The vital functions that the PI3K pathway and its link to the mTOR pathway are highlighted and difficulties in developing effective cancer targeted therapies and feedback systems has also been mentioned, where resistance mechanisms include RAS-mediated oncogenic changes and active PI3K signalling.

Modulating macrophage-mediated programmed cell removal: An attractive strategy for cancer therapy

Macrophage-mediated programmed cell removal (PrCR) is crucial for the identification and elimination of needless cells that maintain tissue homeostasis. The efficacy of PrCR depends on the balance between pro-phagocytic "eat me" signals and anti-phagocytic "don't eat me" signals. Recently, a growing number of studies have shown that tumourigenesis and progression are closely associated with PrCR. In the tumour microenvironment, PrCR activated by the "eat me" signal is counterbalanced by the "don't eat me" signal of CD47/SIRPα, resulting in tumour immune escape. Therefore, targeting exciting "eat me" signalling while simultaneously suppressing "don't eat me" signalling and eventually inducing macrophages to produce effective PrCR will be a very attractive antitumour strategy. Here, we comprehensively review the functions of PrCR-activating signal molecules (CRT, PS, Annexin1, SLAMF7) and PrCR-inhibiting signal molecules (CD47/SIRPα, MHC-I/LILRB1, CD24/Siglec-10, SLAMF3, SLAMF4, PD-1/PD-L1, CD31, GD2, VCAM1), the interactions between these molecules, and Warburg effect. In addition, we highlight the molecular regulatory mechanisms that affect immune system function by exciting or suppressing PrCR. Finally, we review the research advances in tumour therapy by activating PrCR and discuss the challenges and potential solutions to smooth the way for tumour treatment strategies that target PrCR.

Maintaining the Balance: Regulation of NK Cell Activity

Natural Killer (NK) cells, integral components of the innate immune system, play a crucial role in the protection against intracellular threats. Their cytotoxic power requires that activation is tightly controlled, and in this, they take a unique position within the immune system. Rather than depending on the engagement of a single activating receptor, their activation involves a delicate balance between inhibitory and activating signals mediated through an array of surface molecules. Only when this cumulative balance surpasses a specific threshold do NK cells initiate their activity. Remarkably, the activation threshold of NK cells remains robust even when cells express vastly different repertoires of inhibitory and activating receptors. These threshold values seem to be influenced by NK cell interactions with their environment during development and after release from the bone marrow. Understanding how NK cells integrate this intricate pattern of stimuli is an ongoing area of research, particularly relevant for cellular therapies seeking to harness the anti-cancer potential of these cells by modifying surface receptor expression. In this review, we will explore some of the current dogmas regarding NK cell activation and discuss recent literature addressing advances in our understanding of this field.

Immunoproteasome acted as immunotherapy 'coffee companion' in advanced carcinoma therapy

Immunoproteasome is a specialized form of proteasome which plays a crucial role in antigen processing and presentation, and enhances immune responses against malignant cells. This review explores the role of immunoproteasome in the anti-tumor immune responses, including immune surveillance and modulation of the tumor microenvironment, as well as its potential as a target for cancer immunotherapy. Furthermore, we have also discussed the therapeutic potential of immunoproteasome inhibitors, strategies to enhance antigen presentation and combination therapies. The ongoing trials and case studies in urology, melanoma, lung, colorectal, and breast cancers have also been summarized. Finally, the challenges facing clinical translation of immunoproteasome-targeted therapies, such as toxicity and resistance mechanisms, and the future research directions have been addressed. This review underscores the significance of targeting the immunoproteasome in combination with other immunotherapies for solid tumors and its potential broader applications in other diseases.

Combinatorial macrophage induced innate immunotherapy against Ewing sarcoma: Turning "Two Keys" simultaneously

BACKGROUND

Macrophages play important roles in phagocytosing tumor cells. However, tumors escape macrophage phagocytosis in part through the expression of anti-phagocytic signals, most commonly CD47. In Ewing sarcoma (ES), we found that tumor cells utilize dual mechanisms to evade macrophage clearance by simultaneously over-expressing CD47 and down-regulating cell surface calreticulin (csCRT), the pro-phagocytic signal. Here, we investigate the combination of a CD47 blockade (magrolimab, MAG) to inhibit the anti-phagocytic signal and a chemotherapy regimen (doxorubicin, DOX) to enhance the pro-phagocytic signal to induce macrophage phagocytosis of ES cells in vitro and inhibit tumor growth and metastasis in vivo.

METHODS

Macrophages were derived from human peripheral blood monocytes by granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF). Flow cytometry- and microscopy-based in-vitro phagocytosis assays were performed to evaluate macrophage phagocytosis of ES cells. Annexin-V assay was performed to evaluate apoptosis. CD47 was knocked out by CRISPR/Cas9 approach. ES cell-based and patient-derived-xenograft (PDX)-based mouse models were utilized to assess the effects of MAG and/or DOX on ES tumor development and animal survival. RNA-Seq combined with CIBERSORTx analysis was utilized to identify changes in tumor cell transcriptome and tumor infiltrating immune cell profiling in MAG and/or DOX treated xenograft tumors.

RESULTS

We found that MAG significantly increased macrophage phagocytosis of ES cells in vitro (p < 0.01) and had significant effect on reducing tumor burden (p < 0.01) and increasing survival in NSG mouse model (p < 0.001). The csCRT level on ES cells was significantly enhanced by DOX in a dose- and time-dependent manner (p < 0.01). Importantly, DOX combined with MAG significantly enhanced macrophage phagocytosis of ES cells in vitro (p < 0.01) and significantly decreased tumor burden (p < 0.01) and lung metastasis (p < 0.0001) and extended animal survival in vivo in two different mouse models of ES (p < 0.0001). Furthermore, we identified CD38, CD209, CD163 and CD206 as potential markers for ES-phagocytic macrophages. Moreover, we found increased M2 macrophage infiltration and decreased expression of Cd209 in the tumor microenvironment of MAG and DOX combinatorial therapy treated tumors.

CONCLUSIONS

By turning "two keys" simultaneously to reactivate macrophage phagocytic activity, our data demonstrated an effective and highly translatable alternative therapeutic approach utilizing innate (tumor associated macrophages) immunotherapy against high-risk metastatic ES.

Integration of bioinformatics and machine learning strategies identifies APM-related gene signatures to predict clinical outcomes and therapeutic responses for breast cancer patients

BACKGROUND

Tumor antigenicity and efficiency of antigen presentation jointly influence tumor immunogenicity, which largely determines the effectiveness of immune checkpoint blockade (ICB). However, the role of altered antigen processing and presentation machinery (APM) in breast cancer (BRCA) has not been fully elucidated.

METHODS

A series of bioinformatic analyses and machine learning strategies were performed to construct APM-related gene signatures to guide personalized treatment for BRCA patients. A single-sample gene set enrichment analysis (ssGSEA) algorithm and weighted gene co-expression network analysis (WGCNA) were combined to screen for BRCA-specific APM-related genes. The non-negative matrix factorization (NMF) algorithm was used to divide the cohort into different clusters and the fgsea algorithm was applied to investigate the altered signaling pathways. Random survival forest (RSF) and the least absolute shrinkage and selection operator (Lasso) Cox regression analysis were combined to construct an APM-related risk score (APMrs) signature to predict overall survival. Furthermore, a nomogram and decision tree were generated to improve predictive accuracy and risk stratification for individual patients. Based on Tumor Immune Dysfunction and Exclusion (TIDE) method, random forest (RF) and Lasso logistic regression model were combined to establish an APM-related immunotherapeutic response score (APMis). Finally, immune infiltration, immunomodulators, mutational patterns, and potentially applicable drugs were comprehensively analyzed in different APM-related risk groups. IHC staining was used to assess the expression of APM-related genes in clinical samples.

RESULTS

In this study, APMrs and APMis showed favorable performances in risk stratification and therapeutic prediction for BRCA patients. APMrs exhibited more powerful prognostic capacity and accurate survival prediction compared to conventional clinicopathological features. APMrs was closely associated with distinct mutational patterns, immune cell infiltration and immunomodulators expression. Furthermore, the two APM-related gene signatures were independently validated in external cohorts with prognosis or immunotherapeutic responses. Potential applicable drugs and targets were mined in the APMrs-high group. APM-related genes were further validated in our in-house samples.

CONCLUSION

The APM-related gene signatures established in our study could improve the personalized assessment of survival risk and guide ICB decision-making for BRCA patients.

Calreticulin Expression in Human Carcinomas: A Systematic Review and Meta-Analysis

OBJECTIVE

The present study performed a systematic review and meta-analysis of observational studies on whether calreticulin levels could represent a prognostic factor in carcinoma patients. Calreticulin (CRT) is a multifunctional protein in the endoplasmic reticulum that can play distinct roles in different cancers.

METHODS

The search was performed in PubMed, Scopus, the Cochrane Library, Web of Science, Lilacs, Science Direct, Embase, Bireme, and SciELO databases. After a full-text evaluation, only 14 articles remained. The RoBANS tool assessed the risk of bias. The meta-analysis was performed with R software, and the odds ratio (OR) was the effect measure. The random effects model was chosen, and the quality of evidence was evaluated according to GRADE.

RESULT

The most frequent carcinomas were in the breasts and the colon. CRT expression varied according to carcinoma origin and type, but these diseases had a prevalence of high CRT levels, indicating tumor progression. The high CRT levels were associated with lymph node metastasis (OR = 3.06 [1.71; 5.48]/p = 0.0002/I2 = 0%). All included articles had a blinding bias.

CONCLUSION

High CRT levels may represent a prognostic factor for metastatic lymph nodes in carcinoma patients.

Prognostic and Clinical Significance of Human Leukocyte Antigen Class I Expression in Breast Cancer: A Meta-Analysis

BACKGROUND

The value of human leukocyte antigen (HLA; also known as major histocompatibility complex) class I expression for the prediction of breast cancer survival outcomes remains unclear. We conducted a meta-analysis to explore the prognostic significance of this expression.

MATERIALS AND METHODS

We searched electronic databases to identify reports on associations of HLA class I protein or mRNA expression with survival outcomes and clinicopathological factors in the breast cancer context. Pooled hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were used to conduct a quantitative meta-analysis.

RESULTS

The sample comprised eight studies involving 3590 patients. Only the classical HLA class Ia (HLA-ABC) molecules studies were included in this meta-analysis. Elevated HLA class I protein expression was found to be significantly related to better disease-free survival (DFS) (HR 0.58, 95% CI 0.35-0.95, P = 0.03), particularly among patients with triple-negative breast cancer (TNBC) (HR 0.31, 95% CI 0.18-0.52, P < 0.001), but not to overall survival. It was also associated with estrogen receptor (ER) negativity (OR 1.71, 95% CI 1.24-2.35, P = 0.001), progesterone receptor (PR) negativity (OR 1.49, 95% CI 1.22-1.81, P < 0.001), human epidermal growth factor receptor 2 (HER2) positivity (OR 1.51, 95% CI 1.18-1.94, P = 0.001), TNBC (OR 1.68, 95% CI 1.15-2.45, P < 0.01), high Ki-67 indices (OR 2.06, 95% CI 1.62-2.61, P < 0.001), and high nuclear grades (OR 2.67, 95% CI 2.17-3.29, P < 0.001).

CONCLUSION

This meta-analysis demonstrated that enhanced HLA class I protein expression is significantly associated with the better DFS of patients with breast cancer, especially TNBC, as well as with ER and PR negativity, HER2 positivity, TNBC, and high Ki-67 indices and nuclear grades. The immune target HLA class I may serve as a prognostic indicator for breast cancer.

Human Leukocyte Antigen Class I Antigen-Processing Machinery Upregulation by Anticancer Therapies in the Era of Checkpoint Inhibitors: A Review

IMPORTANCE

Although typically impressive, objective responses to immune checkpoint inhibitors (ICIs) occur in only 12.5% of patients with advanced cancer. The majority of patients do not respond due to cell-intrinsic resistance mechanisms, including human leukocyte antigen (HLA) class I antigen-processing machinery (APM) defects. The APM defects, which have a negative effect on neoantigen presentation to cytotoxic T lymphocytes (CTLs), are present in the majority of malignant tumors. These defects are caused by gene variations in less than 25% of cases and by dysregulated signaling and/or epigenetic changes in most of the remaining cases, making them frequently correctable. This narrative review summarizes the growing clinical evidence that chemotherapy, targeted therapies, and, to a lesser extent, radiotherapy can correct HLA class I APM defects in cancer cells and improve responses to ICIs.

OBSERVATIONS

Most chemotherapeutics enhance HLA class I APM component expression and function in cancer cells, tumor CTL infiltration, and responses to ICIs in preclinical and clinical models. Despite preclinical evidence, radiotherapy does not appear to upregulate HLA class I expression in patients and does not enhance the efficacy of ICIs in clinical settings. The latter findings underscore the need to optimize the dose and schedule of radiation and timing of ICI administration to maximize their immunogenic synergy. By increasing DNA and chromatin accessibility, epigenetic agents (histone deacetylase inhibitors, DNA methyltransferase inhibitors, and EZH2 inhibitors) enhance HLA class I APM component expression and function in many cancer types, a crucial contributor to their synergy with ICIs in patients. Furthermore, epidermal growth factor receptor (EGFR) inhibitors and BRAF/mitogen-activated protein kinase kinase inhibitors are effective at upregulating HLA class I expression in EGFR- and BRAF-variant tumors, respectively; these changes may contribute to the clinical responses induced by these inhibitors in combination with ICIs.

CONCLUSIONS AND RELEVANCE

This narrative review summarizes evidence indicating that chemotherapy and targeted therapies are effective at enhancing HLA class I APM component expression and function in cancer cells. The resulting increased immunogenicity and recognition and elimination of cancer cells by cognate CTLs contributes to the antitumor activity of these therapies as well as to their synergy with ICIs.

Overexpression of immunoproteasome low-molecular-mass polypeptide 7 and inhibiting role of next-generation proteasome inhibitor ONX 0912 on cell growth in glioma

OBJECTIVES

The aim of this study was to determine the expression level of immunoproteasome and its clinical significance in glioma preliminarily. Furthermore, we studied the function and molecular mechanism of proteasome inhibitor ONX 0912 on glioma cell.

MATERIALS AND METHODS

The expression of immunoproteasome in glioma and tumor-adjacent brain tissues was detected by western blot. Immunohistochemical technique was used to detect the expression of low-molecular-mass polypeptide 7 in 55 cases of glioma tissues and 6 cases of tumor-adjacent brain tissues. Chi-square test was used to analyze the relationship between the expression level of low-molecular-mass polypeptide 7 and clinical characteristics. Kaplan-Meier method and Cox regression analysis were applied to analyze the correlation between low-molecular-mass polypeptide 7 expression and prognosis of patients. 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2Htetrazolium) (MTS) proliferation assay was introduced to detect the impact of ONX 0912 on proliferation of glioma cells. Western blot was used to detect the apoptosis- and autophagy-related protein in glioma cell treated with ONX 0912.

RESULTS

Our results showed that only low-molecular-mass polypeptide 7 expression was notably upregulated in gliomas in comparison with tumor-adjacent brain tissues and further increased in malignant gliomas compared with benign gliomas (P < 0.01). In the multivariate Cox proportional regression analyses, it was evident that low-molecular-mass polypeptide 7 was an independent unfavorable prognostic factor (P < 0.05). The results of MTS assay showed that ONX 0912 could inhibit the proliferation of glioma cell. Besides, we found that ONX 0912 could prompt apoptosis and autophagosome accumulation, which may be responsible for inhibiting glioma cell proliferation.

CONCLUSION

In conclusion, our results indicated that low-molecular-mass polypeptide 7 might be a candidate prognostic biomarker, and proteasome inhibitor ONX 0912 might act as a potential treatment agent for glioma.

Polymorphisms of Antigen-Presenting Machinery Genes in Non-Small Cell Lung Cancer: Different Impact on Disease Risk and Clinical Parameters in Smokers and Never-Smokers

Lung cancer is strongly associated with cigarette smoking; nevertheless some never-smokers develop cancer. Immune eradication of cancer cells is dependent on polymorphisms of HLA class I molecules and antigen-processing machinery (APM) components. We have already published highly significant associations of single nucleotide polymorphisms (SNPs) of the ERAP1 gene with non-small cell lung cancer (NSCLC) in Chinese, but not in Polish populations. However, the smoking status of participants was not known in the previous study. Here, we compared the distribution of APM polymorphic variants in larger cohorts of Polish patients with NSCLC and controls, stratified according to their smoking status. We found significant but opposite associations in never-smokers and in smokers of all tested SNPs (rs26653, rs2287987, rs30187, and rs27044) but one (rs26618) in ERAP1. No significant associations were seen in other genes. Haplotype analysis indicated that the distribution of many ERAP1/2 haplotypes is opposite, depending on smoking status. Additionally, haplotypic combination of low activity ERAP1 and the lack of an active form of ERAP2 seems to favor the disease in never-smokers. We also revealed interesting associations of some APM polymorphisms with: age at diagnosis (ERAP1 rs26653), disease stage (ERAP1 rs27044, PSMB9 rs17587), overall survival (ERAP1 rs30187), and response to chemotherapy (ERAP1 rs27044). The results presented here may suggest the important role for ERAP1 in the anti-cancer response, which is different in smokers versus never-smokers, depending to some extent on the presence of ERAP2, and affecting NSCLC clinical course.

Playing hide and seek: Tumor cells in control of MHC class I antigen presentation

MHC class I (MHC-I) molecules present a blueprint of the intracellular proteome to T cells allowing them to control infection or malignant transformation. As a response, pathogens and tumor cells often downmodulate MHC-I mediated antigen presentation to escape from immune surveillance. Although the fundamental rules of antigen presentation are known in detail, the players in this system are not saturated and new modules of regulation have recently been uncovered. Here, we update the understanding of antigen presentation by MHC-I molecules and how this can be exploited by tumors to prevent exposure of the intracellular proteome. This knowledge can provide new ways to improve immune responses against tumors and pathogens.

The Tumor Microenvironment and Immunotherapy in Prostate and Bladder Cancer

Bladder cancer has been successfully treated with immunotherapy, whereas prostate cancer is a cold tumor with inadequate immune-related treatment response. A greater understanding of the tumor microenvironment and methods for harnessing the immune system to address tumor growth will be needed to improve immunotherapies for both prostate and bladder cancer. Here, we provide an overview of prostate and bladder cancer, including fundamental aspects of the disease and treatment, the elaborate cellular makeup of the tumor microenvironment, and methods for exploiting relevant pathways to develop more effective treatments.

The Role of Antigen Processing and Presentation in Cancer and the Efficacy of Immune Checkpoint Inhibitor Immunotherapy

Recent clinical successes of cancer immunotherapy using immune checkpoint inhibitors (ICIs) are rapidly changing the landscape of cancer treatment. Regardless of initial impressive clinical results though, the therapeutic benefit of ICIs appears to be limited to a subset of patients and tumor types. Recent analyses have revealed that the potency of ICI therapies depends on the efficient presentation of tumor-specific antigens by cancer cells and professional antigen presenting cells. Here, we review current knowledge on the role of antigen presentation in cancer. We focus on intracellular antigen processing and presentation by Major Histocompatibility class I (MHCI) molecules and how it can affect cancer immune evasion. Finally, we discuss the pharmacological tractability of manipulating intracellular antigen processing as a complementary approach to enhance tumor immunogenicity and the effectiveness of ICI immunotherapy.

Recurrent bladder cancer in aging societies: Importance of major histocompatibility complex class I antigen presentation

Aging is associated with an insufficient immune response that may lead to the initiation and progression of various malignancies. Bladder cancer (BC), prevalent in elderly patients, predominantly presents as recurrent nonmuscle invasive BC that requires further treatment. There is much interest in the activation of patients' immune cells with the focus on CD8+ T cells. Successful therapy should also ensure the efficient presentation of BC antigens by major histocompatibility complex (MHC) class I molecules. The purpose of this systematic review is to present the existing literature on the role of MHC class I in BC research and therapy. The bibliographic databases PubMed and Web of Science were searched for articles published between January 2009 and September 2020 that addressed MHC class I relationship to BC. We searched for available relevant publications on MHC class I and its role and regulation in BC, aging and MHC class I importance in BC immunotherapy. Based on the provided evidence, we propose that the loss of MHC class I expression in BC may lead to its recurrence after the transurethral resection and unresponsiveness to Bacillus Calmette-Guerin immunotherapy. We discuss different ways to enhance MHC class I antigen presentation to CD8+ T cells in BC treatment. The immune status characterized by MHC class I expression patterns and cancer-infiltrating immune cells may provide valuable prognostic information about which patients may benefit from transurethral resection of BC and additional immunotherapy.

CD8+ T Cell Co-Expressed Genes Correlate With Clinical Phenotype and Microenvironments of Urothelial Cancer

Purpose

To identify immune-related co-expressed genes that promote CD8⁺ T cell infiltration in bladder cancer, and to explore the interactions among relevant genes in the tumor microenvironment.

Method

We obtained bladder cancer gene matrix and clinical information data from TCGA, GSE32894 and GSE48075. The “estimate” package was used to calculate tumor purity and immune score. The CIBERSORT algorithm was used to assess CD8⁺ T cell proportions. Weighted gene co-expression network analysis was used to identify the co-expression modules with CD8⁺ T cell proportions and bladder tumor purity. Subsequently, we performed correlation analysis among angiogenesis factors, angiogenesis inhibitors, immune inflammatory responses, and CD8⁺ T cell related genes in tumor microenvironment.

Results

A CD8⁺ T cell related co-expression network was identified. Eight co-expressed genes (PSMB8, PSMB9, PSMB10, PSME2, TAP1, IRF1, FBOX6, ETV7) were identified as CD8⁺ T cell-related genes that promoted infiltration of CD8⁺ T cells, and were enriched in the MHC class I tumor antigen presentation process. The proteins level encoded by these genes (PSMB10, PSMB9, PSMB8, TAP1, IRF1, and FBXO6) were lower in the high clinical grade patients, which suggested the clinical phenotype correlation both in mRNA and protein levels. These factors negatively correlated with angiogenesis factors and positively correlated with angiogenesis inhibitors. PD-1 and PD-L1 positively correlated with these genes which suggested PD-1 expression level positively correlated with the biological process composed by these co-expression genes. In the high expression group of these genes, inflammation and immune response were more intense, and the tumor purity was lower, suggesting that these genes were immune protective factors that improved the prognosis in patients with bladder cancer.

Conclusion

These co-expressed genes promote high levels of infiltration of CD8⁺ T cells in an immunoproteasome process involved in MHC class I molecules. The mechanism might provide new pathways for treatment of patients who are insensitive to PD-1 immunotherapy due to low degrees of CD8⁺ T cell infiltration.

Gene signature of antigen processing and presentation machinery predicts response to checkpoint blockade in non-small cell lung cancer (NSCLC) and melanoma

Background

Limited data exist on the role of alterations in HLA Class I antigen processing and presentation machinery in mediating response to immune checkpoint blockade (ICB).

Methods

This retrospective cohort study analyzed transcriptional profiles from pre-treatment tumor samples of 51 chemotherapy-refractory advanced non-small cell lung cancer (NSCLC) patients and two independent melanoma cohorts treated with ICB. An antigen processing machinery (APM) score was generated utilizing eight genes associated with APM (B2M, CALR, NLRC5, PSMB9, PSME1, PSME3, RFX5, and HSP90AB1). Associations were made for therapeutic response, progression-free survival (PFS) and overall survival (OS).

Results

In NSCLC, the APM score was significantly higher in responders compared with non-responders (p=0.0001). An APM score above the median value for the cohort was associated with improved PFS (HR 0.34 (0.18 to 0.64), p=0.001) and OS (HR 0.44 (0.23 to 0.83), p=0.006). The APM score was correlated with an inflammation score based on the established T-cell-inflamed resistance gene expression profile (Pearson’s r=0.58, p<0.0001). However, the APM score better predicted response to ICB relative to the inflammation score with area under a receiving operating characteristics curve of 0.84 and 0.70 for PFS and OS, respectively. In a cohort of 14 high-risk resectable stage III/IV melanoma patients treated with neoadjuvant anti-PD1 ICB, a higher APM score was associated with improved disease-free survival (HR: 0.08 (0.01 to 0.50), p=0.0065). In an additional independent melanoma cohort of 27 metastatic patients treated with ICB, a higher APM score was associated with improved OS (HR 0.29 (0.09 to 0.89), p=0.044).

Conclusion

Our data demonstrate that defects in antigen presentation may be an important feature in predicting outcomes to ICB in both lung cancer and melanoma.

Role of Human Leukocyte Antigen System as A Predictive Biomarker for Checkpoint-Based Immunotherapy in Cancer Patients

Recent advances in cancer immunotherapy have clearly shown that checkpoint-based immunotherapy is effective in a small subgroup of cancer patients. However, no effective predictive biomarker has been identified so far. The major histocompatibility complex, better known in humans as human leukocyte antigen (HLA), is a very polymorphic gene complex consisting of more than 200 genes. It has a crucial role in activating an appropriate host immune response against pathogens and tumor cells by discriminating self and non-self peptides. Several lines of evidence have shown that down-regulation of expression of HLA class I antigen derived peptide complexes by cancer cells is a mechanism of tumor immune escape and is often associated to poor prognosis in cancer patients. In addition, it has also been shown that HLA class I and II antigen expression, as well as defects in the antigen processing machinery complex, may predict tumor responses in cancer immunotherapy. Nevertheless, the role of HLA in predicting tumor responses to checkpoint-based immunotherapy is still debated. In this review, firstly, we will describe the structure and function of the HLA system. Secondly, we will summarize the HLA defects and their clinical significance in cancer patients. Thirdly, we will review the potential role of the HLA as a predictive biomarker for checkpoint-based immunotherapy in cancer patients. Lastly, we will discuss the potential strategies that may restore HLA function to implement novel therapeutic strategies in cancer patients.

Calreticulin and cancer

Calreticulin (CALR) is an endoplasmic reticulum (ER)-resident protein involved in a spectrum of cellular processes. In healthy cells, CALR operates as a chaperone and Ca²⁺ buffer to assist correct protein folding within the ER. Besides favoring the maintenance of cellular proteostasis, these cell-intrinsic CALR functions support Ca²⁺-dependent processes, such as adhesion and integrin signaling, and ensure normal antigen presentation on MHC Class I molecules. Moreover, cancer cells succumbing to immunogenic cell death (ICD) expose CALR on their surface, which promotes the uptake of cell corpses by professional phagocytes and ultimately supports the initiation of anticancer immunity. Thus, loss-of-function CALR mutations promote oncogenesis not only as they impair cellular homeostasis in healthy cells, but also as they compromise natural and therapy-driven immunosurveillance. However, the prognostic impact of total or membrane-exposed CALR levels appears to vary considerably with cancer type. For instance, while genetic CALR defects promote pre-neoplastic myeloproliferation, patients with myeloproliferative neoplasms bearing CALR mutations often experience improved overall survival as compared to patients bearing wild-type CALR. Here, we discuss the context-dependent impact of CALR on malignant transformation, tumor progression and response to cancer therapy.

Tumor microenvironment-related dendritic cell deficiency: a target to enhance tumor immunotherapy

Dendritic cells (DCs), as specialized antigen-presenting cells, are essential for the initiation of specific T cell responses in innate antitumor immunity and, in certain cases, support humoral responses to inhibit tumor development. Mounting evidence suggests that the DC system displays a broad spectrum of dysfunctional status in the tumor microenvironment (TME), which ultimately affects antitumor immune responses. DC-based therapy can restore the function of DCs in the TME, thus showing a promising potential in tumor therapy. In this review, we provide an overview of the DC deficiency caused by various factors in the TME and discuss proposed strategies to reverse DC deficiency and the applications of novel combinatorial DC-based therapy for immune normalization of the tumor.

Immune Responses in Bladder Cancer-Role of Immune Cell Populations, Prognostic Factors and Therapeutic Implications

Immunosurveillance, which describes the immunologically mediated elimination of transformed cells, has been widely accepted in the context of bladder cancer for many decades with the successful use of Bacillus-Calmette Guerin for superficial bladder cancer since the 1970s. With the emergence of checkpoint inhibitor blockade in the treatment of urothelial cancers, there has been a resurgent interest in the immunology of bladder cancer. The theory of cancer immunoediting proposes that the immune system has both pro-tumorigenic and anti-tumor effects, the balance between the two determining the progression of an individual tumor. However, whilst there is evidence for the action of various immune cell populations in bladder cancer, a cohesive picture of the immune response to bladder cancer and its driving forces are still lacking. Additionally, little is still known about the normal immune landscape of the bladder. Future progress in bladder cancer therapeutic approaches will require a strong foundation in understanding the immunology of this disease. This review considers the evidence for the role of the main immune cell populations, both innate and adaptive, in the immune response to bladder cancer. Recent research and overarching themes in the immune response to bladder cancer are explored. The minimal evidence regarding the normal immune landscape of the human bladder is also summarized to contextualize downstream immune responses. Of specific interest are the innate and myeloid populations, some of which are resident in the human bladder and which have significant effects on downstream adaptive tumor immunity. We discuss factors which restrain the efficacy of populations known to have anti-tumor activity such as cytotoxic T cells, including the constraints on checkpoint blockade. Additionally, the effects on the immune response of tumor intrinsic factors such as the genomic subtype of bladder cancer and the effect of common therapies such as chemotherapy and intravesical Bacillus Calmette-Guerin are considered. A significant theme is the polarization of immune responses within the tumor by a heavily immunosuppressive tumor microenvironment which affects the phenotype of multiple innate and adaptive populations. Throughout, clinical implications are discussed with suggestions for future research directions and therapeutic targeting.

Understanding dynamic interactions in the prostate tumor microenvironment

Complex and dynamic are 2 words that best explain the prostate tumor microenvironment (TME). These words also exemplify the challenges inherent in developing and translating the latest therapeutic advances into clinical benefit for patients with localized and advanced prostate cancer. This issue explores the various cell types and interactions in the prostate TME and how new research findings are being leveraged into therapeutic concepts for our patients.

Targeting immune cells for cancer therapy

Recent years have seen a renaissance in the research linking inflammation and cancer with immune cells playing a central role in smouldering inflammation in the tumor microenvironment. Diverse immune cell types infiltrate the tumor microenvironment, and the dynamic tumor-immune cell interplay gives rise to a rich milieu of cytokines and growth factors. Fundamentally, this intricate cross-talk creates the conducive condition for tumor cell proliferation, survival and metastasis. Interestingly, the prominent impact of immune cells is expounded in their contrary pro-tumoral role, as well as their potential anti-cancer cellular weaponry. The latter is known as immunotherapy, a concept born out of evidence that tumors are susceptible to immune defence and that by manipulating the immune system, tumor growth can be successfully restrained. Naturally, a deeper understanding of the multifaceted roles of various immune cell types thus contributes toward developing innovative anti-cancer strategies. Therefore, in this review we first outline the roles played by the major immune cell types, such as macrophages, neutrophils, natural killer cells, T cells and B cells. We then explain the recently-explored strategies of immunomodulation and discuss some important approaches via an immunology perspective.

Tumor-associated calreticulin variants functionally compromise the peptide loading complex and impair its recruitment of MHC-I

Major histocompatibility complex-I-β₂m dimers (MHC-I) bind peptides derived from intracellular proteins, enabling the immune system to distinguish between normal cells and those expressing pathogen-derived or mutant proteins. The peptides bind to MHC-I in the endoplasmic reticulum (ER), and this binding is facilitated by the peptide loading complex (PLC), which contains calreticulin (CRT). CRT associates with MHC-I via a conserved glycan present on MHC-I and recruits it to the PLC for peptide binding. Somatic frameshift mutations in CRT (CRT-FS) drive the proliferation of a subset of myeloproliferative neoplasms, which are chronic blood tumors. All CRT-FS proteins have a C-terminal sequence lacking the normal ER-retention signal and possessing a net negative charge rather than the normal positive charge. We characterized the effect of CRT-FS on antigen presentation by MHC-I in human cells. Our results indicate that CRT-FS cannot mediate CRT's peptide loading function in the PLC. Cells lacking CRT exhibited reduced surface MHC-I levels, consistent with reduced binding of high-affinity peptides, and this was not reversed by CRT-FS expression. CRT-FS was secreted and not detectably associated with the PLC, leading to poor MHC-I recruitment, although CRT-FS could still associate with MHC-I in a glycan-dependent manner. The addition of an ER-retention sequence to CRT-FS restored its association with the PLC but did not rescue MHC-I recruitment or its surface expression, indicating that the CRT-FS mutants functionally compromise the PLC. MHC-I down-regulation permits tumor cells to evade immune surveillance, and these findings may therefore be relevant for designing effective immunotherapies for managing myeloproliferative neoplasms.

Exploiting natural killer group 2D receptors for CAR T-cell therapy

Chimeric antigen receptors (CARs) are genetically engineered proteins that combine an extracellular antigen-specific recognition domain with one or several intracellular T-cell signaling domains. When expressed in T cells, these CARs specifically trigger T-cell activation upon antigen recognition. While the clinical proof of principle of CAR T-cell therapy has been established in hematological cancers, CAR T cells are only at the early stages of being explored to tackle solid cancers. This special report discusses the concept of exploiting natural killer cell receptors as an approach that could broaden the specificity of CAR T cells and potentially enhance the efficacy of this therapy against solid tumors. New data demonstrating feasibility of this approach in humans and supporting the ongoing clinical trial are also presented.

The Pathophysiological Impact of HLA Class Ia and HLA-G Expression and Regulatory T Cells in Malignant Melanoma: A Review

Malignant melanoma, a very common type of cancer, is a rapidly growing cancer of the skin with an increase in incidence among the Caucasian population. The disease is seen through all age groups and is very common in the younger age groups. Several studies have examined the risk factors and pathophysiological mechanisms of malignant melanoma, which have enlightened our understanding of the development of the disease, but we have still to fully understand the complex immunological interactions. The examination of the interaction between the human leucocyte antigen (HLA) system and prognostic outcome has shown interesting results, and a correlation between the down- or upregulation of these antigens and prognosis has been seen through many different types of cancer. In malignant melanoma, HLA class Ia has been seen to influence the effects of pharmaceutical drug treatment as well as the overall prognosis, and the HLA class Ib and regulatory T cells have been correlated with tumor progression. Although there is still no standardized immunological treatment worldwide, the interaction between the human leucocyte antigen (HLA) system and tumor progression seems to be a promising focus in the way of optimizing the treatment of malignant melanoma.

Immunological and clinical significance of HLA class I antigen processing machinery component defects in malignant cells

Experimental as well as clinical studies demonstrate that the immune system plays a major role in controlling generation and progression of tumors. The cancer immunoediting theory supports the notion that tumor cell immunogenicity is dynamically shaped by the immune system, as it eliminates immunogenic tumor cells in the early stage of the disease and then edits their antigenicity. The end result is the generation of a tumor cell population able to escape from immune recognition and elimination by tumor infiltrating lymphocytes. Two major mechanisms, which affect the target cells and the effector phase of the immune response, play a crucial role in the editing process. One is represented by the downregulation of tumor antigen (TA) processing and presentation because of abnormalities in the HLA class I antigen processing machinery (APM). The other one is represented by the anergy of effector immune infiltrates in the tumor microenvironment caused by aberrant inhibitory signals triggered by immune checkpoint receptor (ICR) ligands, such as programmed death ligand-1 (PD-L1). In this review, we will focus on tumor immune escape mechanisms caused by defects in HLA class I APM component expression and/or function in different types of cancer, with emphasis on head and neck cancer (HNC). We will also discuss the immunological implications and clinical relevance of these HLA class I APM abnormalities. Finally, we will describe strategies to counteract defective TA presentation with the expectation that they will enhance tumor recognition and elimination by tumor infiltrating effector T cells.

Ly49 receptors: evolution, genetic diversity, and impact on immunity

Natural killer (NK) cells express cell surface receptors that recognize class I major histocompatibility complex (MHC-I) molecules to distinguish between healthy and unhealthy cells. The multigenic and polymorphic nature of the MHC-I genes has influenced the convergent evolution of similarly polymorphic and diversified NK cell receptor families: the C-type lectin-like Ly49 receptors in mice, and the killer cell immunoglobulin-like receptors (KIRs) in humans. Although structurally distinct, both receptor families have similar functions in terms of MHC-I recognition and downstream signal transduction, and they regulate multiple aspects of NK cell biology during development and after maturation as fully differentiated and functionally competent cells. The Ly49 gene locus has undergone rapid, lineage-specific expansions and contractions resulting in multiple distinct haplotypes of variable gene number, allelic diversity, and MHC-I ligand specificity. This in turn has influenced the type and degree of Ly49 receptor expression on NK cells, and their contribution to immunity in different mouse strains. In this review, we have attempted to describe the evolutionary processes that have shaped strain-specific Ly49 receptor repertoires, and their impact on NK cell functions during health and disease.

Licensed and Unlicensed NK Cells: Differential Roles in Cancer and Viral Control

Natural killer (NK) cells are known for their well characterized ability to control viral infections and eliminate tumor cells. Through their repertoire of activating and inhibitory receptors, NK cells are able to survey different potential target cells for various surface markers, such as MHC-I – which signals to the NK cell that the target is healthy – as well as stress ligands or viral proteins, which alert the NK cell to the aberrant state of the target and initiate a response. According to the “licensing” hypothesis, interactions between self-specific MHC-I receptors – Ly49 in mice and KIR in humans – and self-MHC-I molecules during NK cell development is crucial for NK cell functionality. However, there also exists a large proportion of NK cells in mice and humans, which lack self-specific MHC-I receptors and are consequentially “unlicensed.” While the licensed NK cell subset plays a major role in the control of MHC-I-deficient tumors, this review will go on to highlight the important role of the unlicensed NK cell subset in the control of MHC-I-expressing tumors, as well as in viral control. Unlike the licensed NK cells, unlicensed NK cells seem to benefit from the lack of self-specific inhibitory receptors, which could otherwise be exploited by some aberrant cells for immunoevasion by upregulating the expression of ligands or mimic ligands for these receptors.

Epigenetic changes within the promoter regions of antigen processing machinery family genes in Kazakh primary esophageal squamous cell carcinoma

The esophageal squamous cell carcinoma (ESCC) is thought to develop through a multi-stage process. Epigenetic gene silencing constitutes an alternative or complementary mechanism to mutational events in tumorigenesis. Posttranscriptional regulation of human leukocyte antigen class I (HLA-I) and antigen processing machinery (APM) proteins expression may be associated with novel epigenetic modifications in cancer development. In the present study, we determined the expression levels of HLA-I antigen and APM components by immunohistochemistry. Then by a bisulfite-sequencing PCR (BSP) approach, we identified target CpG islands methylated at the gene promoter region of APM family genes in a ESCC cell line (ECa109), and further quantitative analysis of CpG site specific methylation of these genes in cases of Kazakh primary ESCCs with corresponding non-cancerous esophageal tissues using the Sequenom MassARRAY platform. Here we showed that the development of ESCCs was accompanied by partial or total loss of protein expression of HLA-B, TAP2, LMP7, tapasin and ERp57. The results demonstrated that although no statistical significance was found of global target CpG fragment methylation level sof HLA-B, TAP2, tapasin and ERp57 genes between ESCC and corresponding non-cancerous esophageal tissues, there was significant differences in the methylation level of several single sites between the two groups. Of thesse only the global methylation level of LMP7 gene target fragments was statistically higher (0.0517±0.0357) in Kazakh esophageal cancer than in neighboring normal tissues (0.0380±0.0214, p<0.05). Our results suggest that multiple CpG sites, but not methylation of every site leads to down regulation or deletion of gene expression. Only some of them result in genetic transcription, and silencing of HLA-B, ERp57, and LMP7 expression through hypermethylation of the promoters or other mechanisms may contribute to mechanisms of tumor escape from immune surveillance in Kazakh esophageal carcinogenesis.

HLA class I is most tightly linked to levels of tapasin compared with other antigen-processing proteins in glioblastoma

Background:

Tumour cells can evade the immune system by dysregulation of human leukocyte antigens (HLA-I). Low quantity and/or altered quality of HLA-I cell surface expression is the result of either HLA-I alterations or dysregulations of proteins of the antigen-processing machinery (APM). Tapasin is an APM protein dedicated to the maturation of HLA-I and dysregulation of tapasin has been linked to higher malignancy in several different tumours.

Methods:

We studied the expression of APM components and HLA-I, as well as HLA-I tapasin-dependency profiles in glioblastoma tissues and corresponding cell lines.

Results:

Tapasin displayed the strongest correlation to HLA-I heavy chain but also clustered with β₂-microglobulin, transporter associated with antigen processing (TAP) and LMP. Moreover, tapasin also correlated to survival of glioblastoma patients. Some APM components, for example, TAP1/TAP2 and LMP2/LMP7, showed variable but coordinated expression, whereas ERAP1/ERAP2 displayed an imbalanced expression pattern. Furthermore, analysis of HLA-I profiles revealed variable tapasin dependence of HLA-I allomorphs in glioblastoma patients.

Conclusions:

Expression of APM proteins is highly variable between glioblastomas. Tapasin stands out as the APM component strongest correlated to HLA-I expression and we proved that HLA-I profiles in glioblastoma patients include tapasin-dependent allomorphs. The level of tapasin was also correlated with patient survival time. Our results support the need for individualisation of immunotherapy protocols.

Reduced Expression of the Antigen Processing Machinery Components TAP2, LMP2, and LMP7 in Tonsillar and Base of Tongue Cancer and Implications for Clinical Outcome

OBJECTIVES: Patients with human papillomavirus (HPV)–positive tonsillar squamous cell carcinoma (TSCC) and base of tongue squamous cell carcinoma (BOTSCC) have a better clinical outcome than those with corresponding HPV-negative tumors. Moreover, there is a strong positive correlation between absent/low as opposed to strong HLA class I expression and favorable clinical outcome for HPV-positive tumors, while the reverse applies to HPV-negative tumors. The expression of the antigen processing machinery (APM) components TAP1, TAP2, LMP2, and LMP7 in these tumors in relation to HPV status, HLA class I expression, each other, and clinical outcome was therefore investigated. MATERIAL AND METHODS: Formalin-fixed paraffin-embedded TSCC and BOTSCC, derived from 151 patients and previously analyzed for HPV DNA, HLA class I, and LMP10 expression were stained by immunohistochemistry for TAP1, TAP2, LMP2, and LMP7. RESULTS: Absent/low TAP2, LMP2, and LMP7 expression, similar to HLA class I and LMP10, was common in TSCC and BOTSCC, irrespective of HPV status. Expression of TAP1 and TAP2 was correlated, as was LMP2 to LMP7. LMP2 and LMP7 expression was also associated to HLA class I expression. Moreover, absence of LMP7 was linked to increased disease-free survival in both HPV-positive and HPV-negative cases. CONCLUSION: Reduced expression of TAP2, LMP2, and LMP7 was frequent in TSCC and BOTSCC and their expression as well as that of TAP1 was often interrelated. Furthermore, low LMP7 expression correlated to better clinical outcome and may, together with HPV status, potentially be used for prediction of treatment response.

Augmenting antitumor immune responses with epigenetic modifying agents

Epigenetic silencing of immune-related genes is a striking feature of the cancer genome that occurs in the process of tumorigenesis. This phenomena impacts antigen processing and antigen presentation by tumor cells and facilitates evasion of immunosurveillance. Further modulation of the tumor microenvironment by altered expression of immunosuppressive cytokines impairs antigen-presenting cells and cytolytic T-cell function. The potential reversal of immunosuppression by epigenetic modulation is therefore a promising and versatile therapeutic approach to reinstate endogenous immune recognition and tumor lysis. Pre-clinical studies have identified multiple elements of the immune system that can be modulated by epigenetic mechanisms and result in improved antigen presentation, effector T-cell function, and breakdown of suppressor mechanisms. Recent clinical studies are utilizing epigenetic therapies prior to, or in combination with, immune therapies to improve clinical outcomes.

Endoplasmic reticulum chaperones and oxidoreductases: critical regulators of tumor cell survival and immunorecognition

Endoplasmic reticulum (ER) chaperones and oxidoreductases are abundant enzymes that mediate the production of fully folded secretory and transmembrane proteins. Resisting the Golgi and plasma membrane-directed “bulk flow,” ER chaperones and oxidoreductases enter retrograde trafficking whenever they are pulled outside of the ER by their substrates. Solid tumors are characterized by the increased production of reactive oxygen species (ROS), combined with reduced blood flow that leads to low oxygen supply and ER stress. Under these conditions, hypoxia and the unfolded protein response upregulate their target genes. When this occurs, ER oxidoreductases and chaperones become important regulators of tumor growth. However, under these conditions, these proteins not only promote the folding of proteins, but also alter the properties of the plasma membrane and hence modulate tumor immune recognition. For instance, high levels of calreticulin serve as an “eat-me” signal on the surface of tumor cells. Conversely, both intracellular and surface BiP/GRP78 promotes tumor growth. Other ER folding assistants able to modulate the properties of tumor tissue include protein disulfide isomerase (PDI), Ero1α and GRP94. Understanding the roles and mechanisms of ER chaperones in regulating tumor cell functions and immunorecognition will lead to important insight for the development of novel cancer therapies.

Targeting epigenetic mechanisms for clinical translation: enhancing the efficacy of tumor immunotherapies

The ability to evade host immune surveillance is critical for the survival of tumor cells and is correlated with poor clinical outcomes. Many tumor types have been found to downregulate expression of genes involved in antigen production, processing and presentation to evade immune detection. Recent findings suggest that the mechanisms underlying these immune evasion phenomena extend beyond alterations in DNA sequence to include epigenetic modifications of DNA and associated proteins, including hypermethylation of DNA and altered histone acetylation patterns. This review will summarize alterations in antigen presentation machinery identified in malignant cells, epigenetic mechanisms that can be employed in the downregulation of genes relevant for antigen presentation and translational strategies to target these processes to enhance the efficacy of antitumor immunotherapies.

Ly49 family receptors are required for cancer immunosurveillance mediated by natural killer cells

According to the missing-self hypothesis, natural killer (NK) cells survey for target cells that lack MHC-I molecules. The Ly49 receptor family recognizes loss of MHC-I and is critical for educating NK cells, conferring the ability to eliminate transformed or infected cells. In this study, we evaluated their requirement in innate immune surveillance of cancer cells using genetically manipulated mice with attenuated expression of Ly49 receptors (NKC(KD)) in several models of carcinoma and metastasis. We found that NKC(KD) mice exhibited uncontrolled tumor growth and metastases. Expression of two MHC-I alleles, H-2K(b) and H-2D(b), was decreased in tumors from NKC(KD) mice in support of the likelihood of NK-mediated tumor immunoediting. These tumor cells exhibited directed alterations to their cell surface expression in response to the genetically altered immune environment to evade host recognition. Immunoediting in NKC(KD) mice was restricted to MHC-I molecules, which are ligands for Ly49 receptors, while expression of Rae-1 and Mult1, ligands for another NK cell receptor, NKG2D, were unaffected. Restoring NK cell education in NKC(KD) mice with a transgene for the inhibitory self-MHC-I receptor Ly49I restored suppression of cancer onset and growth. Interestingly, immune surveillance mediated by activating Ly49 receptors remained intact in NKC(KD) mice, as demonstrated by the ability to stimulate the NKG2D receptor with tumor cells or splenocytes expressing Rae-1. Together, our results genetically establish the integral role of Ly49 in NK cell-mediated control of carcinogenesis through MHC-I-dependent missing-self recognition.

Correlation of LMP10 expression and clinical outcome in Human Papillomavirus (HPV) positive and HPV-Negative tonsillar and base of tongue cancer

AIM

To examine LMP10 expression and its possible impact on clinical outcome in human papillomavirus (HPV) positive and HPV-negative tonsillar and base of tongue squamous cell carcinoma (TSCC and BOTSCC).

BACKGROUND

Outcome is better in HPV-positive TSCC and BOTSCC compared to matching HPV-negative tumours, with roughly 80% vs. 40% 5-year disease free survival (DFS) with less aggressive treatment than today's chemoradiotherapy. Since current treatment often results in harmful side effects, less intensive therapy, with sustained patient survival would be an attractive alternative. However, other markers together with HPV status are necessary to select patients and for this purpose LMP10 expression is investigated here in parallel to HPV status and clinical outcome.

MATERIALS AND METHODS

From 385 patients diagnosed between 2000 and 2007 at the Karolinska University Hospital, 278 formalin fixed paraffin embedded TSCC and BOTSCC biopsies, with known HPV DNA status, were tested for LMP10 nuclear and cytoplasmic expression (fraction of positive cells and staining intensity). The data was then correlated to clinical outcome.

RESULTS

An absent/low compared to a moderate/high LMP10 nuclear fraction of positive cells was correlated to a better 3-year DFS in the HPV-positive group of patients (log-rank p = 0.005), but not in the HPV-negative group. In the HPV-negative group of patients, in contrast to the HPV-positive group, moderate/high LMP10 cytoplasmic fraction and weak/moderate/high LMP10 cytoplasmic intensity correlated to a better 3-year DFS (p = 0.003 and p = 0.001) and 3-year overall survival (p = 0.001 and 0.009).

CONCLUSION

LMP10 nuclear expression in the HPV-positive group and LMP10 cytoplasmic expression in the HPV-negative group of patients correlated to better clinical outcome.

Involvement of HLA class I molecules in the immune escape of urologic tumors

CONTEXT AND OBJECTIVE

To analyze the influence of different alterations in human leukocyte antigen class I molecules (HLA I) in renal cell carcinoma, as well as in bladder and prostate cancer. We also study the correlation between HLA I expression and the progression of the disease and the response after immunotherapy protocols.

EVIDENCES ACQUISITION

It has been shown, experimentally, that the immune system can recognize and kill neoplastic cells. By analyzing the expression of HLA I molecules on the surface of cancer cells, we were able to study the tumor escape mechanisms against the immune system.

EVIDENCES SYNTHESIS

Alteration or irreversible damage in HLA I molecules is used by the neoplastic cells to escape the immune system. The function of these molecules is to recognize endogenous peptides and present them to T cells of the immune system. There is a clear relationship between HLA I reversible alterations and success of therapy. Irreversible lesions also imply a lack of response to treatment. The immune system activation can reverse HLA I molecules expression in tumors with reversible lesions, whereas tumors with irreversible ones do not respond to such activation. Determine the type of altered HLA I molecules in tumors is of paramount importance when choosing the type of treatment to keep looking for therapeutic success. Those tumors with reversible lesions can be treated with traditional immunotherapy; however, tumour with irreversible alterations should follow alternative protocols, such as the use of viral vectors carrying the HLA genes to achieve damaged re-expression of the protein.

CONCLUSION

From studies in urologic tumors, we can conclude that the HLA I molecules play a key role in these tumors escape to the immune system.

The prognostic impact of human leukocyte antigen (HLA) class I antigen abnormalities in salivary gland cancer. A clinicopathological study of 288 cases

AIMS

To study abnormalities of proteins of the major histocompatibility complex class I in a series of 288 salivary gland carcinomas, and to correlate findings with patients' overall survival (OS).

METHODS AND RESULTS

Protein expression of human leukocyte antigen (HLA)-A, heavy chain (HC)-10, β2 -microglobulin, low molecular weight polypeptides (LMP) 2 and 7, transporters associated with antigen processing (TAP) 1 and 2, calnexin, calreticulin, endoplasmic reticulum (ER) p57 and tapasin was evaluated by immunohistochemistry and semiquantitatively analyzed. As compared with normal salivary gland tissue, HLA-A, LMP7, TAP2 and HLA class I were significantly down-regulated in salivary gland carcinomas, whereas β2 -microglobulin, calnexin, LMP2, and TAP1 were upregulated. Expression of calreticulin, ERp57 and tapasin was unaltered. In univariate Kaplan-Meier analyses, low expression of LMP7 (P = 0.005) and high expression of β2 -microglobulin (P = 0.028), HLA-A (P < 0.001), TAP1 (P = 0.01), and tapasin (P < 0.001) were significantly associated with shorter OS. In multivariate analysis incorporating tumour stage, nodal/distant metastasis, and grade, HLA-A (P = 0.014), LMP7 (P = 0.033), and tapasin (P = 0.024), as well as distant metastasis (P = 0.012) and high tumour grade (P < 0.001), remained statistically significant.

CONCLUSION

The prognostic influence of up-regulated HLA-A and tapasin and down-regulated LMP7 may provide a rationale for targeting these specific components of the antigen processing and presentation pathway in salivary gland carcinomas.

MHC class I antigen processing and presenting machinery: organization, function, and defects in tumor cells

The surface presentation of peptides by major histocompatibility complex (MHC) class I molecules is critical to all CD8(+) T-cell adaptive immune responses, including those against tumors. The generation of peptides and their loading on MHC class I molecules is a multistep process involving multiple molecular species that constitute the so-called antigen processing and presenting machinery (APM). The majority of class I peptides begin as proteasome degradation products of cytosolic proteins. Once transported into the endoplasmic reticulum by TAP (transporter associated with antigen processing), peptides are not bound randomly by class I molecules but are chosen by length and sequence, with peptidases editing the raw peptide pool. Aberrations in APM genes and proteins have frequently been observed in human tumors and found to correlate with relevant clinical variables, including tumor grade, tumor stage, disease recurrence, and survival. These findings support the idea that APM defects are immune escape mechanisms that disrupt the tumor cells' ability to be recognized and killed by tumor antigen-specific cytotoxic CD8(+) T cells. Detailed knowledge of APM is crucial for the optimization of T cell-based immunotherapy protocols.

NKG2D ligands as therapeutic targets

The Natural Killer Group 2D (NKG2D) receptor plays an important role in protecting the host from infections and cancer. By recognizing ligands induced on infected or tumor cells, NKG2D modulates lymphocyte activation and promotes immunity to eliminate ligand-expressing cells. Because these ligands are not widely expressed on healthy adult tissue, NKG2D ligands may present a useful target for immunotherapeutic approaches in cancer. Novel therapies targeting NKG2D ligands for the treatment of cancer have shown preclinical success and are poised to enter into clinical trials. In this review, the NKG2D receptor and its ligands are discussed in the context of cancer, infection, and autoimmunity. In addition, therapies targeting NKG2D ligands in cancer are also reviewed.

Association of down-regulated expression of HLA-Ⅰ antigen and endoplasmic reticulum molecular chaperones with clinicopathological features of esophageal squamous cell carcinoma in Xinjiang Kazakh patients

AIM: To investigate the expression of human leukocyte antigen class-Ⅰ(HLA-Ⅰ) and endoplasmic reticulum molecular chaperones and to analyze their relationship with clinicopathological features of esophageal squamous cell carcinoma (ESCC) in Kazakh patients.

METHODS: The expression of HLA-Ⅰand endoplasmic reticulum molecular chaperones was assessed by immunohistochemistry in 50 paraffin-embedded ESCC specimens and tumor-adjacent normal mucosal specimens. The associations of expression of HLA-Ⅰand endoplasmic reticulum molecular chaperones with clinicopathological features of ESCC were analyzed.

RESULTS: The rates of down-regulation or loss of expression of HLA-Ⅰprotein and endoplasmic reticulum molecular chaperones (CNX, Tapasin, and Erp57) were 24%/68%, 20%/48%, 20%/52% and 16%/32% in ESCC, and %/0%,10%/2%,8%/2% and 16%/2% in tumor adjacent normal mucosal specimens. The positive rates of HLA-Ⅰand endoplasmic reticulum molecular chaperones significantly decreased in ESCC compared with control tissue (P < 0.05). HLA-Ⅰexpression was significantly correlated with pathological grade, lymph node metastasis and depth of invasion. Erp57 expression was significantly correlated with vascular invasion, lymph node metastasis and depth of invasion. Tapasin expression was significantly correlated with lymph node metastasis and depth of invasion. Calnexin expression was significantly correlated with all above clinicopathological parameters (all P < 0.05).

CONCLUSION: Expression of HLA-Ⅰand endoplasmic reticulum molecular chaperones was significantly down-regulated in ESCC in Xinjiang Kazakh patients. The abnormal expression of HLA-I and endoplasmic reticulum molecular chaperones is closely related with the occurrence and clinicopathological features of ESCC.

Innovative therapeutic strategies in the treatment of brain metastases

Brain metastases (BM) are the most common intracranial tumors and their incidence is increasing. Untreated brain metastases are associated with a poor prognosis and a poor performance status. Metastasis development involves the migration of a cancer cell from the bulk tumor into the surrounding tissue, extravasation from the blood into tissue elsewhere in the body, and formation of a secondary tumor. In the recent past, important results have been obtained in the management of patients affected by BM, using surgery, radiation therapy, or both. Conventional chemotherapies have generally produced disappointing results, possibly due to their limited ability to penetrate the blood-brain barrier. The advent of new technologies has led to the discovery of novel molecules and pathways that have better depicted the metastatic process. Targeted therapies such as bevacizumab, erlotinib, gefitinib, sunitinib and sorafenib, are all licensed and have demonstrated improved survival in patients with metastatic disease. In this review, we will report current data on targeted therapies. A brief review about brain metastatic process will be also presented.

LMP gene promoter hypermethylation is a mechanism for its down regulation in Kazak's esophageal squamous cell carcinomas

Abnormal hypermethylation of CpG islands not only associated with tumor suppressor genes can lead to repression of gene expression, but also contribute to escape of the tumor from immune surveillance and contribute significantly to tumorigenesis. In the present study, we studied the hypermethylation of low molecular-weight protein (LMP) gene and its regulation on protein expression in biopsies from resected tissues from Kazak's esophageal squamous cell carcinoma (ESCC) patients and their neighboring normal tissues. LMP2 and LMP7 genes promoter region methylation sequences were maped in esophageal cancer cell line Eca109 by bisulfite-sequencing PCR and quantitative detection of methylated DNA from 30 pairs of Kazak's ESCC and adjacent normal tissues by MassARRAY (Sequenom, San Diego, CA, USA) and LMP2 and LMP7 protein expression were analyzed with immunohistochemistry. In Eca109, we identified 6 CG sites methylated from all of 22 CpG sites of LMP7 gene. However, no methylation was found for LMP2. The analysis of the data resulted from the quantitative analysis of single CpG site methylation by Sequenom MassARRAY platform, has shown that the methylation level between two groups CpG sites (CpG_5, CpG_9, CpG_20, CpG_21 and CpG_20) from CpG_1, CpG_2, CpG_3, CpG_4, CpG_5, CpG_6, CpG_7, CpG_8, CpG_9, CpG_10.11, CpG_12.13.14, CpG_15.16.17.18, CpG_19, CpG_20, CpG_21 and CpG_22 significant differences between ESCC and neighboring normal tissues. The analysis of methylation level of whole target CpG fragment indicated that the methylation level of LMP7 was significant higher in ESCC (0.0517 ± 0.0357) than in neighboring normal tissues (0.0380 ± 0.0214, P < 0.05). there was a tendency of decreasing the LMP7 proteins expression as the increasing the methylation level of LMP7 gene promoter regions (F = 7.69, P = 0.041). The LMP7 gene promoter methylation and protein downregulation were correlated at high extent in Kazakh's ESCC patients, and may explain the epigenetic regulation on gene expression.

Post-transcriptional and epigenetic regulation of antigen processing machinery (APM) components and HLA-I in cervical cancers from Uighur women

Normal function of human leukocyte antigen class I (HLA-I) and antigen processing machinery (APM) proteins is required for T cell-mediated anti-tumor or antiviral immunity, whereas the tumor survival indicates a failure of the host in immune surveillance associated with the dysfunction in antigen presentation, mainly due to the deregulation in HLA-I and APM expression or function. The posttranscriptional regulation of HLA-I and APM expression may associate with epigenetic modifications in cancer development which was not described so far. Here we showed that the development of cervical intraepithelial neoplasia (CIN) and cervical squamous cell carcinoma (CSCC) in Uighur women was accompanied with the partial or total loss of protein expression of HLA-I, ß2-m and APM components, including the transporter associated with antigen processing (TAP1/2), low molecular mass protein (LMP2, LMP7), endoplasmic reticulum aminopeptidase 1(ERAP1), chaperone molecules include calreticulin (CLR), calnexin (CNX) and ERp57, and this was proved again by analysis of transcription of the same genes in addition to three genes HLA-A, B and C coding for HLA-I. By bisulfite sequencing approach, we identified target CpG islands methylated at the gene promoter region of TAP1, TAP2, LMP7, tapasin and ERp57 in cervical carcinoma cells. Further analysis of CpG site specific methylation of these genes in cases of CSCC and CIN demonstrated an inverse correlation of altered CpG island methylation of TAP1, LMP7, and ERp57 with changes in protein expression. Moreover, promoter methylation of these genes was significantly higher in cases positive for human papillomavirus 16 (HPV 16) than negative ones. Our results suggested that epigenetic modifications are responsible for the aberrant expression of certain HLA-I and APM genes, and may help to understand unrevealed mechanisms of tumor escape from immune surveillance in cervical carcinogenesis.

The role of classical and non-classical HLA class I antigens in human tumors

In human tumors alterations in the surface expression and/or function of the major histocompatibility complex (MHC) class I antigens are frequently found and equip neoplastic cells with mechanisms to escape immune control. The aberrant expression of HLA class I molecules can be caused by structural alterations or dysregulations of genes encoding the classical HLA class I antigens and/or components of the HLA class I antigen processing machinery (APM). The dysregulation of APM components could occur at the epigenetic, transcriptional or post-transcriptional level. In some malignancies these abnormalities are significantly associated with a higher tumor staging, grading, disease progression and a reduced survival of patients as well as a failure to CD8(+) T cell-based immunotherapies. In addition to HLA class I abnormalities, expression of the non-classical HLA-G antigen is often induced in tumors, which could be mediated by various microenvironmental factors. Interestingly, soluble HLA-G serum and plasma levels have been useful markers for the prediction of some malignancies. The biological consequence of HLA-G expression or sHLA-G is an escape from T and NK cell-mediated recognition. Thus, alterations of non-classical and classical HLA class I antigens and components of the antigen processing pathway provide tumor cells with different mechanisms to inactivate immune responses resulting in tumor growth and evasion from host immune surveillance.