Down-Regulation of HLA Class I Antigen Processing Molecules: An Immune Escape Mechanism of Renal Cell Carcinoma?

Associations between KIR/KIR-ligand genotypes and clinical outcome for patients with advanced solid tumors receiving BEMPEG plus nivolumab combination therapy in the PIVOT-02 trial

Bempegaldesleukin (BEMPEG), a CD122-preferential IL2 pathway agonist, has been shown to induce proliferation and activation of NK cells. NK activation is dependent on the balance of inhibitory and excitatory signals transmitted by NK receptors, including Fc-gamma receptors (FCγRs) and killer immunoglobulin-like receptors (KIRs) along with their KIR-ligands. The repertoire of KIRs/KIR-ligands an individual inherits and the single-nucleotide polymorphisms (SNPs) of FCγRs can influence NK function and affect responses to immunotherapies. In this retrospective analysis of the single-arm PIVOT-02 trial, 200 patients with advanced solid tumors were genotyped for KIR/KIR-ligand gene status and FCγR SNP status and evaluated for associations with clinical outcome. Patients with inhibitory KIR2DL2 and its ligand (HLA-C1) observed significantly greater tumor shrinkage (TS, median change -13.0 vs. 0%) and increased PFS (5.5 vs. 3.3 months) and a trend toward improved OR (31.2 vs. 19.5%) compared to patients with the complementary genotype. Furthermore, patients with KIR2DL2 and its ligand together with inhibitory KIR3DL1 and its ligand (HLA-Bw4) had improved OR (36.5 vs. 19.6%), greater TS (median change -16.1 vs. 0%), and a trend toward prolonged PFS (8.4 vs. 3.6 months) as compared to patients with the complementary genotype. FCγR polymorphisms did not influence OR/PFS/TS.These data show that clinical response to BEMPEG plus nivolumab treatment in the PIVOT-02 trial may be associated with the repertoire of KIR/KIR-ligands an individual inherits. Further investigation and validation of these results may enable KIR/KIR-ligand genotyping to be utilized prospectively for identifying patients likely to benefit from certain cancer immunotherapy regimens.

Inflammatory Networks in Renal Cell Carcinoma

Cancer-associated inflammation has been established as a hallmark feature of almost all solid cancers. Tumor-extrinsic and intrinsic signaling pathways regulate the process of cancer-associated inflammation. Tumor-extrinsic inflammation is triggered by many factors, including infection, obesity, autoimmune disorders, and exposure to toxic and radioactive substances. Intrinsic inflammation can be induced by genomic mutation, genome instability and epigenetic remodeling in cancer cells that promote immunosuppressive traits, inducing the recruitment and activation of inflammatory immune cells. In RCC, many cancer cell-intrinsic alterations are assembled, upregulating inflammatory pathways, which enhance chemokine release and neoantigen expression. Furthermore, immune cells activate the endothelium and induce metabolic shifts, thereby amplifying both the paracrine and autocrine inflammatory loops to promote RCC tumor growth and progression. Together with tumor-extrinsic inflammatory factors, tumor-intrinsic signaling pathways trigger a Janus-faced tumor microenvironment, thereby simultaneously promoting or inhibiting tumor growth. For therapeutic success, it is important to understand the pathomechanisms of cancer-associated inflammation, which promote cancer progression. In this review, we describe the molecular mechanisms of cancer-associated inflammation that influence cancer and immune cell functions, thereby increasing tumor malignancy and anti-cancer resistance. We also discuss the potential of anti-inflammatory treatments, which may provide clinical benefits in RCCs and possible avenues for therapy and future research.

Clinical potential of PD-1/PD-L1 blockade therapy for renal cell carcinoma (RCC): a rapidly evolving strategy

Programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) blockade therapy has become a game-changing therapeutic approach revolutionizing the treatment setting of human malignancies, such as renal cell carcinoma (RCC). Despite the remarkable clinical activity of anti-PD-1 or anti-PD-L1 monoclonal antibodies, only a small portion of patients exhibit a positive response to PD-1/PD-L1 blockade therapy, and the primary or acquired resistance might ultimately favor cancer development in patients with clinical responses. In light of this, recent reports have signified that the addition of other therapeutic modalities to PD-1/PD-L1 blockade therapy might improve clinical responses in advanced RCC patients. Until, combination therapy with PD-1/PD-L1 blockade therapy plus cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitor (ipilimumab) or various vascular endothelial growth factor receptors (VEGFRs) inhibitors axitinib, such as axitinib and cabozantinib, has been approved by the United States Food and Drug Administration (FDA) as first-line treatment for metastatic RCC. In the present review, we have focused on the therapeutic benefits of the PD-1/PD-L1 blockade therapy as a single agent or in combination with other conventional or innovative targeted therapies in RCC patients. We also offer a glimpse into the well-determined prognostic factor associated with the clinical response of RCC patients to PD-1/PD-L1 blockade therapy.

Correlation between low expression of protein disulfide isomerase A3 and lymph node metastasis in papillary thyroid carcinoma and poor prognosis: a clinicopathological study of 1,139 cases with long-term follow-up

The incidence of papillary thyroid carcinoma (PTC) is increasing worldwide. The biomarkers to identify aggressive types of PTC are limited, illustrating the need to establish reliable novel biomarkers. Protein disulfide isomerase A3 (PDIA3) is a chaperone protein that modulates the folding of newly synthesized glycoproteins and stress-responsive proteins in the endoplasmic reticulum. Although the role of PDIA3 in various cancers such as breast, uterine cervix, head and neck, and gastrointestinal tract has been examined, its expression in thyroid cancer has not been reported. We retrospectively reviewed accumulated data with long-term follow-up of 1,139 PTC patients, and investigated the correlation between immunohistochemical expression of PDIA3 in PTC patients and clinicopathological features and prognosis. PDIA3 expression was significantly lower in PTCs compared to normal thyroid tissues (NTT; n = 80, p = 0.002). In PTCs, correlation between low PDIA3 expression and lymph node metastasis (p = 0.018) and the number of positive nodes (p = 0.004) was observed. Patients with low PDIA3 expression exhibited worse cause-specific survival compared to those with high PDIA3 expression (p = 0.013). Our findings indicate that low PDIA3 expression is related to poor clinical outcome in PTC patients, and that PDIA3 may potentially be a novel ancillary biomarker. Further clarification of the biological role of PDIA3 in PTC is warranted for the future clinical application.

Updates on Immunotherapy and Immune Landscape in Renal Clear Cell Carcinoma

Several clinicopathological features of clear cell renal cell carcinomas (ccRCC) contribute to make an "atypical" cancer, including resistance to chemotherapy, sensitivity to anti-angiogenesis therapy and ICIs despite a low mutational burden, and CD8+ T cell infiltration being the predictor for poor prognosis-normally CD8+ T cell infiltration is a good prognostic factor in cancer patients. These "atypical" features have brought researchers to investigate the molecular and immunological mechanisms that lead to the increased T cell infiltrates despite relatively low molecular burdens, as well as to decipher the immune landscape that leads to better response to ICIs. In the present study, we summarize the past and ongoing pivotal clinical trials of immunotherapies for ccRCC, emphasizing the potential molecular and cellular mechanisms that lead to the success or failure of ICI therapy. Single-cell analysis of ccRCC has provided a more thorough and detailed understanding of the tumor immune microenvironment and has facilitated the discovery of molecular biomarkers from the tumor-infiltrating immune cells. We herein will focus on the discussion of some major immune cells, including T cells and tumor-associated macrophages (TAM) in ccRCC. We will further provide some perspectives of using molecular and cellular biomarkers derived from these immune cell types to potentially improve the response rate to ICIs in ccRCC patients.

Clinical Significance of TAP1 and DLL4 Expression in Patients With Locally Advanced Gastric Cancer

BACKGROUND/AIM

Cancer stem cells (CSCs) are reported to associated with cancer metastasis, relapse, and chemoresistance. This study examined the clinical significance of the expression of two CSC markers, the transporter associated with antigen processing 1 (TAP1) and the Delta-like 4 (DLL4) protein, in patients with locally advanced GC.

PATIENTS AND METHODS

This study was performed using samples obtained from 413 pathological stage II/III GC patients after curative gastrectomy. We examined TAP1 and DLL4 expression using immunohistochemical analysis with tissue microarray and examined the association between TAP1 or DLL4 expression, clinicopathological factors and survival.

RESULTS

High TAP1 expression was associated with better overall survival compared to low TAP1 expression (p=0.004). Furthermore, in multivariate analysis, high TAP1 expression was defined as a predictive factor for good survival. There was no significant difference between DLL4 expression and clinicopathological features and overall survival.

CONCLUSION

TAP1 expression may be a useful prognostic marker in patients with locally advanced GC.

Cancer Immune Evasion Through Loss of MHC Class I Antigen Presentation

Major histocompatibility class I (MHC I) molecules bind peptides derived from a cell's expressed genes and then transport and display this antigenic information on the cell surface. This allows CD8 T cells to identify pathological cells that are synthesizing abnormal proteins, such as cancers that are expressing mutated proteins. In order for many cancers to arise and progress, they need to evolve mechanisms to avoid elimination by CD8 T cells. MHC I molecules are not essential for cell survival and therefore one mechanism by which cancers can evade immune control is by losing MHC I antigen presentation machinery (APM). Not only will this impair the ability of natural immune responses to control cancers, but also frustrate immunotherapies that work by re-invigorating anti-tumor CD8 T cells, such as checkpoint blockade. Here we review the evidence that loss of MHC I antigen presentation is a frequent occurrence in many cancers. We discuss new insights into some common underlying mechanisms through which some cancers inactivate the MHC I pathway and consider some possible strategies to overcome this limitation in ways that could restore immune control of tumors and improve immunotherapy.

Comparative Assessment of the WNT/β-Catenin Pathway, CacyBP/SIP, and the Immunoproteasome Subunit LMP7 in Various Histological Types of Renal Cell Carcinoma

Objective

The Wnt/ß-catenin pathway plays an important role in pathogenesis of variety cancers. Most studies on changes in WNT/β-catenin pathway in renal cell carcinoma (RCC) apply only to clear cell RCC, while there are no comparative assessments of this signaling pathway in various histological types of renal tumors in the available literature. Additionally, considering the close relationship between WNT/β-catenin signaling, CacyBP/SIP and proteasomal activity, it seemed worth comparing WNT/β-catenin pathway, CacyBP/SIP and LMP7 immunoproteasome subunit in human samples of clear cell, papillary, and chromophobe RCC.

Methods

Tests were performed on sections of three types of kidney tumors together with surrounding unchanged tissue fragments collected from 50 patients. Samples were divided into three groups depending on the histological type of cancer: clear cell, papillary and chromophobe RCC. Immunohistochemistry and PCR methods were used to identify WNT10A, Fzd5, β-catenin, GSK-3ß, CacyBP/SIP, LMP7, and gene expression.

Results

Immunoreactivity and expression of WNT10A, Fzd5, β-catenin, GSK-3ß, CacyBP/SIP, LMP7 in clear cell RCC was markedly increased compared to non-cancerous kidney tissue. In papillary RCC, immunoreactivity and expression of WNT/β-catenin pathway, CacyBP/SIP, LMP7 was also increased compared to non-malignant kidneys, but it was less pronounced than in clear cell RCC. The least substantial increase in immunoreactivity and expression of WNT/β-catenin pathway, CacyBP/SIP, LMP7 was found in chromophobe RCC, compared to other RCC histological subtypes studied.

Conclusions

Study results suggest an important role of WNT/β-catenin pathway, CacyBP/SIP and LMP7 in RCC carcinogenesis, and may indicate new aspects of pathomechanisms leading to differences in the biology of clear cell, papillary and chromophobe RCC.

The immunology of renal cell carcinoma

Renal cell carcinoma (RCC) is the most common type of kidney cancer and comprises several subtypes with unique characteristics. The most common subtype (~70% of cases) is clear-cell RCC. RCC is considered to be an immunogenic tumour but is known to mediate immune dysfunction in large part by eliciting the infiltration of immune-inhibitory cells, such as regulatory T cells and myeloid-derived suppressor cells, into the tumour microenvironment. Several possible mechanisms have been proposed to explain how these multiple tumour-infiltrating cell types block the development of an effective anti-tumour immune response, including inhibition of the activity of effector T cells and of antigen presenting cells via upregulation of suppressive factors such as checkpoint molecules. Targeting immune suppression using checkpoint inhibition has resulted in clinical responses in some patients with RCC and combinatorial approaches involving checkpoint blockade are now standard of care in patients with advanced RCC. However, a substantial proportion of patients do not benefit from checkpoint blockade. The identification of reliable biomarkers of response to checkpoint blockade is crucial to facilitate improvements in the clinical efficacy of these therapies. In addition, there is a need for the development of other immune-based strategies that address the shortcomings of checkpoint blockade, such as adoptive cell therapies.

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.

SMAR1 favors immunosurveillance of cancer cells by modulating calnexin and MHC I expression

Down-regulation or loss of MHC class I expression is a major mechanism used by cancer cells to evade immunosurveillance and increase their oncogenic potential. MHC I mediated antigen presentation is a complex regulatory process, controlled by antigen processing machinery (APM) dictating immune response. Transcriptional regulation of the APM that can modulate gene expression profile and their correlation to MHC I mediated antigen presentation in cancer cells remain enigmatic. Here, we reveal that Scaffold/Matrix-Associated Region 1- binding protein (SMAR1), positively regulates MHC I surface expression by down-regulating calnexin, an important component of antigen processing machinery (APM) in cancer cells. SMAR1, a bonafide MAR binding protein acts as a transcriptional repressor of several oncogenes. It is down-regulated in higher grades of cancers either through proteasomal degradation or through loss of heterozygosity (LOH) at the Chr.16q24.3 locus where the human homolog of SMAR1 (BANP) has been mapped. It binds to a short MAR region of the calnexin promoter forming a repressor complex in association with GATA2 and HDAC1. A reverse correlation between SMAR1 and calnexin was thus observed in SMAR1-LOH cells and also in tissues from breast cancer patients. To further extrapolate our findings, influenza A (H1N1) virus infection assay was performed. Upon viral infection, the levels of SMAR1 significantly increased resulting in reduced calnexin expression and increased MHC I presentation. Taken together, our observations establish that increased expression of SMAR1 in cancers can positively regulate MHC I surface expression thereby leading to higher chances of tumor regression and elimination of cancer cells.

TGF-β inducible epithelial-to-mesenchymal transition in renal cell carcinoma

Epithelial-to-mesenchymal transition (EMT) is a crucial step in cancer progression and the number one reason for poor prognosis and worse overall survival of patients. Although this essential process has been widely studied in many solid tumors as e.g. melanoma and breast cancer, more detailed research in renal cell carcinoma (RCC) is required, especially for the major EMT-inducer transforming growth factor beta (TGF-β). Here, we provide a study of six different RCC cell lines of two different RCC subtypes and their response to recombinant TGF-β1 treatment. We established a model system shifting the cells to a mesenchymal cell type without losing their mesenchymal character even in the absence of the external stimulus. This model system forms a solid basis for future studies of the EMT process in RCCs to better understand the molecular basis of this process responsible for cancer progression.

Total HLA Class I Antigen Loss with the Downregulation of Antigen-Processing Machinery Components in Two Newly Established Sarcomatoid Hepatocellular Carcinoma Cell Lines

Limited information is currently available concerning HLA class I antigen abnormalities in sarcomatoid hepatocellular carcinoma (sHCC). Here, we have analyzed the growth characteristics and HLA class I antigen status of four sHCC cell lines (sHCC29, sHCC63, sHCC74, and SAR-HCV); the first three were newly established in this study. Among the four, sHCC29 showed the highest growth rate in vitro and tumorigenicity in NOD-SCID mice. Unlike sHCC74 and SAR-HCV, both sHCC29 and sHCC63 had no detectable surface HLA class I antigen expression, alongside undetected intracellular β₂-microglobulin (β₂m) and marked HLA class I heavy chain and selective antigen-processing machinery (APM) component downregulation. The loss of β₂m in sHCC29 and sHCC63 was caused by a >49 kb deletion across the B2M locus, while their downregulation of APM components was transcriptional, reversible by IFN-γ only in several components. β₂m was also undetected in the primary HCC lesions of the patients involved, indicating its in vivo relevance. We report for the first time HLA class I antigen loss with underlying B2M gene deficiency and APM defects in 50% (2 of 4) of the sHCC cell lines tested. These findings may have implications for a proper design of T cell immunotherapy for the treatment of sHCC patients.

Next Generation Cancer Vaccines-Make It Personal!

Dramatic success in cancer immunotherapy has been achieved over the last decade with the introduction of checkpoint inhibitors, leading to response rates higher than with chemotherapy in certain cancer types. These responses are often restricted to cancers that have a high mutational burden and show pre-existing T-cell infiltrates. Despite extensive efforts, therapeutic vaccines have been mostly unsuccessful in the clinic. With the introduction of next generation sequencing, the identification of individual mutations is possible, enabling the production of personalized cancer vaccines. Combining immune check point inhibitors to overcome the immunosuppressive microenvironment and personalized cancer vaccines for directing the host immune system against the chosen antigens might be a promising treatment strategy.

Targeting the tumor microenvironment to improve natural killer cell-based immunotherapies: On being in the right place at the right time, with resilience

Natural killer (NK) cell immunotherapies that target solid tumors require NK cells in the proper place, at the right time, with optimal function and a susceptible target cell. Basic research and clinical correlative studies have provided evidence, for certain malignancies, that intratumoral NK cells delay tumor progression. Whether NK cells exert anti-tumor effects for solid tumors is determined by a number of factors including homing and activating receptor expression by NK cells themselves and the sensitivity of tumor cells to be targets of NK cell cytolysis, which depends on the chemokine and NK cell-inhibitory and activating receptor ligand expression by tumor cells. Chemotherapeutic agents that increase NK cell-activating receptor ligands on tumor cells have been clinically promising as well as ectopic gene expression in NK cells with factors that overcome the suppressive mechanisms of the tumor microenvironment (TME). Identifying agents that decrease myeloid-derived suppressor cells (MDSC) or T regulatory (Treg) cell frequencies or function would be important to co-administer with adoptively transferred NK cells to ameliorate immunosuppressive TMEs. Thus, studies indicate that critical factors for NK cell immunotherapies targeting the TMEs are: being in the right place at the right time, with resilience.

IFNA-AS1 regulates CD4+ T cell activation in myasthenia gravis though HLA-DRB1

Abnormal CD4⁺T cell activation is known to play roles in the pathogenesis of myasthenia gravis (MG). However, little is known about the mechanisms underlying the roles of lncRNAs in regulating CD4⁺ T cell. In this study, we discovered that the lncRNA IFNG-AS1 is abnormally expressed in MG patients associated with quantitative myasthenia gravis (QMG) and the positive anti-AchR Ab levels patients. IFNG-AS1 influenced Th1/Treg cell proliferation and regulated the expression levels of their transcription factors in an experimental autoimmune myasthenia gravis (EAMG)model. IFNG-AS1 could reduce the expression of HLA-DRB and HLA-DOB and they had a negative correlation in MG. Furthermore IFNG-AS1 influenced the expression levels of CD40L and CD4⁺ T cells activation in MG patient partly depend on effecting the HLA-DRB1 expression. It suggests that IFNG-AS1 may be involved in CD4⁺T cell-mediated immune responses in MG.

Antigen processing and immune regulation in the response to tumours

The MHC class I and II antigen processing and presentation pathways display peptides to circulating CD8⁺ cytotoxic and CD4⁺ helper T cells respectively to enable pathogens and transformed cells to be identified. Once detected, T cells become activated and either directly kill the infected / transformed cells (CD8⁺ cytotoxic T lymphocytes) or orchestrate the activation of the adaptive immune response (CD4⁺ T cells). The immune surveillance of transformed/tumour cells drives alteration of the antigen processing and presentation pathways to evade detection and hence the immune response. Evasion of the immune response is a significant event tumour development and considered one of the hallmarks of cancer. To avoid immune recognition, tumours employ a multitude of strategies with most resulting in a down-regulation of the MHC class I expression at the cell surface, significantly impairing the ability of CD8⁺ cytotoxic T lymphocytes to recognize the tumour. Alteration of the expression of key players in antigen processing not only affects MHC class I expression but also significantly alters the repertoire of peptides being presented. These modified peptide repertoires may serve to further reduce the presentation of tumour-specific/associated antigenic epitopes to aid immune evasion and tumour progression. Here we review the modifications to the antigen processing and presentation pathway in tumours and how it affects the anti-tumour immune response, considering the role of tumour-infiltrating cell populations and highlighting possible future therapeutic targets.

HLA-E expression and its clinical relevance in human renal cell carcinoma

The non-classical human leukocyte antigen E (HLA-E) expression is frequently overexpressed in tumor diseases, transplants and virus-infected cells and represents an immunomodulatory molecule by binding to the receptors CD94/NKG2A, -B and -C on NK and T cells. Due to its immune suppressive features HLA-E expression might represent an important mechanism of tumors to escape immune surveillance.While an aberrant expression of the non-classical HLA-G antigen in human renal cell carcinoma (RCC) has been demonstrated to be associated with a worse outcome of patients and reduced sensitivity to immune effector cell-mediated cytotoxicity, the expression and function of HLA-E has not yet been analyzed in this tumor entity.Higher levels of HLA-E transcripts were detected in all RCC cell lines and tumor lesions, which were tested in comparison to normal kidney epithelium. Immunohistochemical staining of a tissue microarray (TMA) using the HLA-E-specific monoclonal antibody TFL-033 recognizing the cytoplasmic HLA-E α-chain as monomer revealed a heterogeneous HLA-E expression in RCC lesions with the highest frequency in chromophobe RCC when compared to other RCC subtypes. HLA-E expression did not correlate with the frequency of CD3+, CD4+, CD8+ and FoxP3+ immune cell infiltrations, but showed an inverse correlation with infiltrating CD56+ cells. In contrast to HLA-G, HLA-E expression in RCCs was not statistically significant associated with a decreased disease specific survival. These data suggest that HLA-E overexpression frequently occurs in RCC and correlates with reduced immunogenicity.

Major histocompatibility complex I upregulation in clear cell renal cell carcinoma is associated with increased survival

Objective

To examine the prognostic value of tumor major histocompatibility complex I (MHCI) expression on survival and recurrence in patients with clear cell renal cell carcinoma (RCC).

Methods

Fifty-three patients that underwent nephrectomy at our institution for clear cell RCC (T1-T3) with ≥4 years of follow-up were queried from our nephrectomy database. Immunohistochemical staining for MHCI was performed on tumor specimens and MHCI expression was quantified with an automated image analysis technique. Patients were divided into high and low MHCI expression groups in order to study the relationship between MHCI expression and prognosis using the Kaplan-Meier method and log-rank test.

Results

Overall survival and recurrence free survival were increased in the high MHCI expression group compared to the low MHCI expression group (log-rank, p = 0.036 and p = 0.028, respectively). Patients alive at the end of the study had higher MHCI expression (mean positivity score 0.82) than those that died of disease (mean positivity score 0.76, t test, p = 0.030). Patients that did not develop recurrence during the study period had higher MHCI expression (mean positivity score 0.83) than those that did develop recurrence (mean positivity score 0.78), but this difference was not significant (t test, p = 0.079).

Conclusion

Our data demonstrate that high MHCI expression confers improved overall and recurrence free survival in patients with clear cell RCC and could serve as an important prognostic tool in identifying high-risk patients.

Overcoming tumor-mediated immunosuppression

Mechanisms of tumor-mediated immunosuppression have been described for several solid and hematological tumors. Tumors inhibit immune responses by attraction of immunosuppressive lymphocytic populations, secretion of immunosuppressive cytokines or expression of surface molecules, which inhibit immune responses by induction of anergy or apoptosis in tumor-infiltrating lymphocytes. This tumor-mediated immunosuppression represents a major obstacle to many immunotherapeutic or conventional therapeutic approaches. In this review we discuss how tumor-mediated immunosuppression interferes with different immunotherapeutic approaches and then give an overview of strategies to overcome it. Particular emphasis is placed on agents or approaches already transferred into clinical settings. Finally the success of immune checkpoint inhibitors targeting CTLA-4 or the PD-1 pathway highlights the enormous therapeutic potential of an effective overcoming of tumor-mediated immunosuppression.

NLRC5 expression in tumors and its role as a negative prognostic indicator in stage III non-small-cell lung cancer patients

Major histocompatibility complex (MHC) class I molecules have a crucial role in tumor immune evasion; however, the association of MHC class I molecules with outcomes in cancer patients remains controversial. Nucleotide-binding oligomerization-like receptor family caspase recruitment domain-containing 5 (NLRC5) has been reported to be a MHC class I transactivator. However, the expression and function of NLRC5 in cancer remains to be elucidated. The present study aimed to retrospectively examine NLRC5 expression in human tumor tissues and its association with clinical outcomes of non-small-cell lung cancer (NSCLC) stage III patients. The expression of MHC class I and NLRC5 in NSCLC were detected using immunohistochemistry (IHC). The association between their expression levels was assessed using the Pearson's χ² test and their association with survival was assessed using Kaplan-Meier analysis and the log-rank test. In addition, the expression of NLRC5 and MHC class I were examined in 323 cases of seven other types of tumors and their correlations were studied. The results revealed that the expression of NLRC5 was correlated with that of MHC class I in NSCLC patients (P=0.008). MHC class I-positive and nuclear NLRC5-positive NSCLC patients were found to have shorter overall survival (OS) rates (log-rank, P=0.032 and P=0.039, respectively). In addition, in the seven different tumor types, there was a significant correlation between MHC class I and NLRC5 nuclear expression (P<0.001) as well as MHC class I and NLRC5 cytoplasmic expression (P=0.003). In conclusion, NLRC5 was demonstrated to be widely expressed in eight tumor tissues and its expression was correlated with that of MHC class I. Of note, nuclear NLRC5-negative and MHC class I-negative stage III NSCLC patients had improved OS rates compared to those with positive expression. Therefore, NLRC5 and MHC class I may be negative prognostic indicators in NSCLC stage III patients.

A catalog of HLA type, HLA expression, and neo-epitope candidates in human cancer cell lines

Cancer cell lines are a tremendous resource for cancer biology and therapy development. These multipurpose tools are commonly used to examine the genetic origin of cancers, to identify potential novel tumor targets, such as tumor antigens for vaccine devel-opment, and utilized to screen potential therapies in preclinical studies. Mutations, gene expression, and drug sensitivity have been determined for many cell lines using next-generation sequencing (NGS). However, the human leukocyte antigen (HLA) type and HLA expression of tumor cell lines, characterizations necessary for the development of cancer vaccines, have remained largely incomplete and, such information, when available, has been distributed in many publications. Here, we determine the 4-digit HLA type and HLA expression of 167 cancer and 10 non-cancer cell lines from publically available RNA-Seq data. We use standard NGS RNA-Seq short reads from "whole transcriptome" sequencing, map reads to known HLA types, and statistically determine HLA type, heterozygosity, and expression. First, we present previously unreported HLA Class I and II genotypes. Second, we determine HLA expression levels in each cancer cell line, providing insights into HLA downregulation and loss in cancer. Third, using these results, we provide a fundamental cell line "barcode" to track samples and prevent sample annotation swaps and contamination. Fourth, we integrate the cancer cell-line specific HLA types and HLA expression with available cell-line specific mutation information and existing HLA binding prediction algorithms to make a catalog of predicted antigenic mutations in each cell line. The compilation of our results are a fundamental resource for all researchers selecting specific cancer cell lines based on the HLA type and HLA expression, as well as for the development of immunotherapeutic tools for novel cancer treatment modalities.

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.

Downregulation of ERp57 expression is associated with poor prognosis in early-stage cervical cancer

OBJECTIVE

We investigated the clinical significance of ERp57 in the progression of cervical cancer.

METHODS

mRNA and protein expression of ERp57 in cervical neoplasias were examined.

RESULTS

ERp57 mRNA expression was significantly decreased in cervical cancers. Immunohistochemistry revealed that ERp57 expression in 123 cervical cancers was down-regulated compared to cervical intraepithelial neoplasias or normal tissues (p < 0.001). Low ERp57 expression was significantly associated with worse overall survival (HR = 12.19, p = 0.018).

CONCLUSIONS

Low ERp57 expression independently predicts a poor outcome for patients with cervical cancer, supporting the notion that ERp57 may be a promising novel cancer target.

Dendritic cell-based immunotherapy in prevention and treatment of renal cell carcinoma: efficacy, safety, and activity of Ad-GM·CAIX in immunocompetent mouse models

The dendritic cell vaccine DC-Ad-GM·CAIX is an active, specific immunotherapy with the potential of providing a safe and effective therapy against renal cell carcinoma (RCC). Using immunocompetent Balb/c mouse models we tested the efficacy and mechanism of the vaccine to prevent and treat the growth of a syngeneic RCC (RENCA) engineered to overexpress the human TAA carbonic anhydrase IX (NPR-IX). In a prevention model, NPR-IX tumor development was specifically and significantly delayed by 13 days in DC-Ad-GM·CAIX-treated mice (P < 0.001), tumor volumes were 79% smaller (day 24, P < 0.007), and body weight was maintained at study termination compared with the controls. Six of these mice remained tumor-free for > 1 year. In a treatment model, NPR-IX tumors remained smaller in DC-Ad-GM·CAIX-treated mice for 8 days (P < 0.002), achieving a 60% growth inhibition at termination. No vaccine-related organ toxicity was observed in either model. The critical mechanistic parameter separating responsive from nonresponsive tumors was hCAIX protein expression, demonstrated by aggressive growth of tumors that did not express hCAIX protein and in sham-treated mice (DC-Ad-Null). No murine serum anti-hCAIX antibodies were detected. Moreover, altered mechanisms of immunoediting as a means for immune evasion were suggested by differential gene expression (Ccl1, Hmgb1, Fgl2, Cd209a, and Klra2) and therapy evasion miRNAs (miR-1186, miR-98, miR-5097, miR-1942, and miR-708) in tumors that evaded DC-Ad-GM·CAIX immunotherapy. This is the first study in immunocompetent mice that provides a proof of concept for the specificity, efficacy, safety, and activity of the DC-Ad-GM·CAIX immunotherapy, forming the basis for a first-in-human phase I trial in RCC patients.

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.

TIPE2 mRNA overexpression correlates with TNM staging in renal cell carcinoma tissues

Tumor necrosis factor α-induced protein-8 like-2 (TIPE2) is a gene that maintains immune homeostasis. The aim of the present study was to determine whether TIPE2 is associated with renal cell carcinoma (RCC) progression. The mRNA expression levels of TIPE2 and myxoma resistance protein 1 (MX1; a type I interferon-inducible gene) were investigated in renal cancer tissues. A total of 46 patients who fulfilled the RCC criteria of the World Health Organization (WHO; revised in 2004) and 39 control patients with renal contusions requiring surgical extraction were enrolled. Tumor and normal renal tissues were sampled from all subjects through surgery. Total RNA was extracted and the expression of the TIPE2 and MX1 genes was evaluated by quantitative polymerase chain reaction (qPCR) analysis. TIPE2 mRNA expression was significantly upregulated in the RCC patients compared with the controls (P=0.001), while MX1 mRNA expression was decreased in the RCC patients compared with the controls (P=0.0001). Furthermore, the TIPE2 mRNA expression levels were positively correlated with TNM staging (r=0.803, P=0.001) and showed a negative correlation with the MX1 mRNA expression levels (r=−0.763, P=0.001) in the RCC patients. These results indicate that the increased expression of the TIPE2 gene is markedly associated with RCC and suggests an important role for the TIPE2 gene in the pathogenesis of RCC.

Down-regulation of human leukocyte antigen class I (HLA-I) is associated with poor prognosis in patients with clear cell renal cell carcinoma

Human leukocyte antigen class I (HLA-I) molecules are transmembrane glycoproteins that have been reported to be down-regulated in multiple types of human malignancies, including clear cell renal cell carcinoma (CCRCC). However, only one study has investigated its prognostic value in CCRCC. In the present study, HLA-I protein expression was analyzed in 120 archived, paraffin-embedded CCRCC samples and 10 adjacent normal tissues using immunohistochemistry. The correlation between HLA-I expression and clinicopathological factors was evaluated by the χ(2) test. Patients' overall survival was analyzed by the Kaplan-Meier method. HLA-I down-regulation was observed in 38.3% (46/120) of renal tumor samples, but only in 10% (1/10) of adjacent normal tissues. Statistical analysis showed a significant correlation of HLA-I expression with TNM stage, lymph node metastasis, and Fuhrman grade. Patients with tumors displaying down-regulation of HLA-I showed significantly shorter overall survival (P=0.021, log-rank test). More importantly, multivariate analysis indicated that down-regulation of HLA-I was an independent prognostic factor for CCRCC patients (P=0.033). Overall, our data suggest that HLA-I down-regulation is associated with tumor progression and a poor prognosis in CCRCC patients, and emphasize the importance of HLA-I in natural and therapeutic immune surveillance of patients with CCRCC.

Correlation of HLA-A02* genotype and HLA class I antigen down-regulation with the prognosis of epithelial ovarian cancer

BACKGROUND

In recent years, evidence is accumulating that cancer cells develop strategies to escape immune recognition. HLA class I HC down-regulation is one of the most investigated. In addition, different HLA haplotypes are known to correlate to both risk of acquiring diseases and also prognosis in survival of disease or cancer. We have previously shown that patients with serous adenocarcinoma of the ovary in advanced surgical stage disease have a particularly poor prognosis if they carry the HLA-A02* genotype. We aimed to study the relationship between HLA-A02* genotype in these patients and the subsequent HLA class I HC protein product defects in the tumour tissue.

MATERIALS AND METHODS

One hundred and sixty-two paraffin-embedded tumour lesions obtained from Swedish women with epithelial ovarian cancer were stained with HLA class I heavy chain (HC) and β(2)-microglobulin (β(2)-m)-specific monoclonal antibodies (mAb). Healthy ovary and tonsil tissue served as a control. The HLA genotype of these patients was determined by PCR/sequence-specific primer method. The probability of survival was calculated using the Kaplan-Meier method, and the hazard ratio (HR) was estimated using proportional hazard regression.

RESULTS

Immunohistochemical staining of ovarian cancer lesions with mAb showed a significantly higher frequency of HLA class I HC and β(2)-m down-regulation in patients with worse prognosis (WP) than in those with better prognosis. In univariate analysis, both HLA class I HC down-regulation in ovarian cancer lesions and WP were associated with poor survival. In multivariate Cox-analysis, the WP group (all with an HLA-A02* genotype) had a significant higher HR to HLA class I HC down-regulation.

CONCLUSIONS

HLA-A02* is a valuable prognostic biomarker in epithelial ovarian cancer. HLA class I HC loss and/or down-regulation was significantly more frequent in tumour tissues from HLA-A02* positive patients with serous adenocarcinoma surgical stage III-IV. In multivariate analysis, we show that the prognostic impact is reasonably correlated to the HLA genetic rather than to the expression of its protein products.

MHC class I-related antigen-processing machinery component defects in feline mammary carcinoma

Defects in HLA class I antigen-processing machinery (APM) component expression and/or function are frequent in human tumors. These defects may provide tumor cells with a mechanism to escape from recognition and destruction by HLA class I antigen-restricted, tumor antigen-specific cytotoxic T cells. However, expression and functional properties of MHC class I antigens and APM components in malignant cells in other animal species have been investigated to a limited extent. However, this information can contribute to our understanding of the mechanisms underlying the association of MHC class I antigen and APM component defects with malignant transformation of cells and to identify animal models to validate targeted therapies to correct these defects. To overcome this limitation in the present study, we have investigated the expression of the catalytic subunits of proteasome (Y, X, and Z) and of immunoproteasome (LMP2, LMP7, and LMP10) as well as of MHC class I heavy chain (HC) in 25 primary feline mammary carcinomas (FMCs) and in 23 matched healthy mammary tissues. We found a reduced expression of MHC class I HC and of LMP2 and LMP7 in tumors compared with normal tissues. Concordantly, proteasomal cleavage specificities in extracts from FMCs were different from those in healthy tissues. In addition, correlation analysis showed that LMP2 and LMP7 were concordantly expressed in FMCs, and their expression was significantly correlated with that of MHC class I HC. The abnormalities we have found in the APM in FMCs may cause a defective processing of some tumor antigens.

Vaccines targeting tumor blood vessel antigens promote CD8(+) T cell-dependent tumor eradication or dormancy in HLA-A2 transgenic mice

We have recently shown that effective cytokine gene therapy of solid tumors in HLA-A2 transgenic (HHD) mice lacking murine MHC class I molecule expression results in the generation of HLA-A2-restricted CD8(+) T effector cells selectively recognizing tumor blood vessel-associated pericytes and/or vascular endothelial cells. Using an HHD model in which HLA-A2(neg) tumor (MC38 colon carcinoma or B16 melanoma) cells are not recognized by the CD8(+) T cell repertoire, we now show that vaccines on the basis of tumor-associated blood vessel Ags (TBVA) elicit protective Tc1-dependent immunity capable of mediating tumor regression or extending overall survival. Vaccine efficacy was not observed if (HLA-A2(neg)) wild-type C57BL/6 mice were instead used as recipient animals. In the HHD model, effective vaccination resulted in profound infiltration of tumor lesions by CD8(+) (but not CD4(+)) T cells, in a coordinate reduction of CD31(+) blood vessels in the tumor microenvironment, and in the "spreading" of CD8(+) T cell responses to alternate TBVA that were not intrinsic to the vaccine. Protective Tc1-mediated immunity was durable and directly recognized pericytes and/or vascular endothelial cells flow-sorted from tumor tissue but not from tumor-uninvolved normal kidneys harvested from these same animals. Strikingly, the depletion of CD8(+), but not CD4(+), T cells at late time points after effective therapy frequently resulted in the recurrence of disease at the site of the regressed primary lesion. This suggests that the vaccine-induced anti-TBVA T cell repertoire can mediate the clinically preferred outcomes of either effectively eradicating tumors or policing a state of (occult) tumor dormancy.

Down-regulation of Human Leukocyte Antigen class I heavy chain in tumors is associated with a poor prognosis in advanced esophageal cancer patients

The HLA class I antigen processing machinery (APM) plays a crucial role in the anticancer immune response. The aim of this study was to assess the clinical significance of APM components in esophageal cancer. A total of 11 esophageal cancer cell lines were evaluated by Western blot analysis for 13 HLA class I APM components. There was a different expression pattern among cancer cell lines for HLA class I heavy chain (HLA-HC), β2 microglobulin, Tapasin, TAP-1, TAP-2, LMP-7 and LMP-10. Immunohistochemical staining utilizing a tissue microarray method for HLA class I APM expression showing different expression patterns among cell lines was performed for 95 surgical specimens from patients with esophageal cancer. Prognostic factors were the down-regulation of HLA-HC, and the up-regulation of β2 microglobulin and TAP-1 in the cancer tissues. Multivariate analysis using a Cox regression model indicated that the down-regulation of HLA-HC, and up-regulation of TAP-1 in cancer tissues are independent, unfavorable prognostic factors (hazard ratio, 2.361 and 2.297; P=0.0141 and 0.0145, respectively). Although there was no significant difference in survival for selected p-stage I and II patients (n=54) in all APM components, only down-regulation of HLA-HC was an unfavorable prognostic factor by a Cox regression model for selected p-stage III and IV patients (n=41). In conclusion, the current results suggest that the down-regulation of HLA-HC in tumors is especially associated with a poor prognosis among advanced esophageal cancer patients.

Mutations of the von Hippel-Lindau gene confer increased susceptibility to natural killer cells of clear-cell renal cell carcinoma

The tumor suppressor gene von Hippel-Lindau (VHL) is involved in the development of sporadic clear-cell renal cell carcinoma (RCC). VHL interferes with angiogenesis and also controls cell adhesion and invasion. Therapies that target VHL-controlled genes are currently being evaluated in RCC patients. RCC is a immunogenic tumor and treatment with interleukin-2 (IL2) or interferon (IFN)-α results in regression in some patients. We used two renal tumor cell lines (RCC6 and RCC4) carrying VHL loss-of-function mutations to investigate the role of mutant VHL in susceptibility to natural killer (NK) cell-mediated lysis. The RCC6 and RCC4 cell lines were transfected with the wild-type gene to restore the function of VHL. The presence of the gene in RCC cells downregulated hypoxia-inducible factor (HIF)-1α and subsequently decreased vascular endothelial growth factor (VEGF) production. Relative to control transfectants and parental cells, pVHL-transfected cell lines activated resting and IL2-activated NK cells less strongly, as assessed by IFNγ secretion, NK degranulation and cell lysis. NKG2A, a human leukocyte antigen (HLA)-I-specific inhibitory NK receptor, controls the lysis of tumor targets. We show that HLA-I expression in RCC-pVHL cells is stronger than that in parental and controls cells, although the expression of activating receptor NK ligands remains unchanged. Blocking NKG2A/HLA-I interactions substantially increased lysis of RCC-pVHL, but had little effect on the lysis of VHL-mutated RCC cell lines. In addition, in response to IFNα, the exponential growth of RCC-pVHL was inhibited more than that of RCC-pE cells, indicating that VHL mutations may be involved in IFNα resistance. These results indicate that a decreased expression of HLA-I molecules in mutated VHL renal tumor cells sensitizes them to NK-mediated lysis. These results suggest that combined immunotherapy with anti-angiogenic drugs may be beneficial for patients with mutated VHL.

Quantification of HLA class I molecules on renal cell carcinoma using Edman degradation

BACKGROUND

Unimpaired HLA class I antigen presentation is a prerequisite for the recognition of tumor cells by cytotoxic T lymphocytes and thus essential for the success of anticancer immunotherapeutic concepts. Several approaches have been taken in the immunotherapy of metastatic renal cell carcinoma (RCC), however of limited success. HLA loss or down-regulation have often been reported and might interfere with immunotherapeutic approaches aimed at the recognition of HLA-presented peptides.

METHODS

We employed a quantitative method of molecular analysis for the comparison of HLA amounts on primary tumor, normal kidney and metastases of RCC, using Edman degradation. We analyzed a series of 47 RCC samples including corresponding renal parenchyma, local lymph node metastases and distant metastases.

RESULTS

Results of quantitative Edman degradation revealed significantly higher HLA yields on primary tumor and metastases compared to normal kidney tissue. This effect was shown not to result from infiltrating immune cells, since tumor-infiltrating lymphocytes had no influence on the overall HLA recovery from tumor tissue. Unexpectedly, we found a higher amount of HLA class I molecules on distant metastases compared to local lymph node metastases.

CONCLUSION

Edman degradation allows the direct quantitative comparison of HLA class I protein expression by tumor or normal tissue and metastases of RCC patients. Our results raise hopes for improving the success and effectiveness of future immunotherapeutic concepts for metastatic RCC.

Biology of HLA-G in cancer: a candidate molecule for therapeutic intervention?

Although the expression of the non-classical HLA class I molecule HLA-G was first reported to be restricted to the fetal-maternal interface on the extravillous cytotrophoblasts, the distribution of HLA-G in normal tissues appears broader than originally described. HLA-G expression was found in embryonic tissues, in adult immune privileged organs, and in cells of the hematopoietic lineage. More interestingly, under pathophysiological conditions HLA-G antigens may be expressed on various types of malignant cells suggesting that HLA-G antigen expression is one strategy used by tumor cells to escape immune surveillance. In this article, we will focus on HLA-G expression in cancers of distinct histology and its association with the clinical course of diseases, on the underlying molecular mechanisms of impaired HLA-G expression, on the immune tolerant function of HLA-G in tumors, and on the use of membrane-bound and soluble HLA-G as a diagnostic or prognostic biomarker to identify tumors and to monitor disease stage, as well as on the use of HLA-G as a novel therapeutic target in cancer.

Distinct molecular mechanisms leading to deficient expression of ER-resident aminopeptidases in melanoma

Immune surveillance of tumour cells by CD8(+) cytotoxic T cells plays a key role in the establishment and control of an anti-tumour response. This process requires the generation of antigenic peptides, which are largely produced by the proteasome in combination with other proteases located in either the cytoplasm and/or the endoplasmic reticulum (ER). The ER-resident aminopeptidases ERAP1 and ERAP2 trim or even destroy HLA class I-binding peptides thereby shaping the peptide repertoire presented for T cell recognition. So far there exists limited information about the expression pattern of ERAP1 and/or ERAP2 in human tumours of distinct histotypes. Therefore, the expression profiles and modes of regulation of both aminopeptidases were determined in a large series of melanoma cell lines. A heterogeneous expression ranging from high to reduced or even total loss of ERAP1 and/or ERAP2 mRNA and/or protein expression was detected, which often could be induced/upregulated by interferon-gamma treatment. The observed altered ERAP1 and/or ERAP2 expression and activity levels were either mediated by sequence alterations affecting the promoter or enzymatic activities, leading to either transcriptional and/or post-transcriptional downregulation mechanisms or limited or excessive processing activities, which both might have an impact on the antigenic peptide repertoire presented on HLA class I molecules.

Down-regulation of HLA class I antigen-processing machinery components in esophageal squamous cell carcinomas: association with disease progression

OBJECTIVE

Lack of human leukocyte antigen (HLA) presentation has been proposed to contribute to the immune evasion of cancer cells in some cancers including esophageal cancer. The aim of this study was to examine the expression of HLA class I antigen and the antigen-processing machinery (APM) components in esophageal squamous cell carcinoma (ESCC) lesions and to assess their association with histopathological characteristics.

MATERIAL AND METHODS

A total of 143 formalin-fixed, paraffin-embedded ESCC lesions collected in two hospitals in Shandong Province of China were studied. The expression levels were determined by immunohistochemistry.

RESULTS

TAP1, TAP2, LMP2, LMP7, beta2m, and HLA class I antigen were lost or down-regulated in 30.8%, 35.0%, 45.0%, 48.0%, 56.0%, and 60.8% of the ESCC lesions tested, respectively. The loss of or down-regulated expressions of HLA class I, beta2m, TAP1, LMP2, and LMP7 in tumor lesions were all significantly correlated to tumor grade and lymph node status. Expression of HLA class I antigens was strongly correlated to the expression levels of beta2m, TAP1, TAP2, LMP2, and LMP7, suggesting APM component defects as a mechanism underlying HLA class I antigen down-regulation in ESCC lesions. Expression of APM components and HLA class I antigens was significantly associated with the extent of intratumoral T-cell infiltration.

CONCLUSIONS

Our results indicate that lack or reduction of HLA class I antigens and expression of APM components in ESCC may render some tumor cells to escape the immunosurveillance mediated by CD8(+) T cells and contribute to the clinical course of ESCC.

Association of HLA class I antigen abnormalities with disease progression and early recurrence in prostate cancer

Defects in HLA class I antigen processing machinery (APM) component expression often have a negative impact on the clinical course of tumors and on the response to T cell-based immunotherapy. Since only scant information is available about the frequency and clinical significance of HLA class I APM component abnormalities in prostate cancer, the APM component expression pattern was analyzed in 59 primary prostate carcinoma, adjacent normal tissues, as well as in prostate carcinoma cell lines. The IFN-gamma inducible proteasome subunits LMP2 and LMP7, TAP1, TAP2, calnexin, calreticulin, ERp57, and tapasin are strongly expressed in the cytoplasm of normal prostate cells, whereas HLA class I heavy chain (HC) and beta(2)-microglobulin are expressed on the cell surface. Most of the APM components were downregulated in a substantial number of prostate cancers. With the exception of HLA class I HC, TAP2 and ERp57 not detectable in about 0.5% of tumor lesions, all other APM components were not detected in at least 21% of lesions analyzed. These APM component defects were associated with a higher Gleason grade of tumors and an early disease recurrence. Prostate carcinoma cell lines also exhibit a heterogeneous, but reduced constitutive APM component expression pattern associated with lack or reduced HLA class I surface antigens, which could be upregulated by IFN-gamma. Our results suggest that HLA class I APM component abnormalities are mainly due to regulatory mechanisms, play a role in the clinical course of prostate cancer and on the outcome of T cell-based immunotherapies.

Systematic comparative protein expression profiling of clear cell renal cell carcinoma: a pilot study based on the separation of tissue specimens by two-dimensional gel electrophoresis

Proteome-based technologies represent powerful tools for the analysis of protein expression profiles, including the identification of potential cancer candidate biomarkers. Thus, here we provide a comprehensive protein expression map for clear cell renal cell carcinoma established by systematic comparative two-dimensional gel electrophoresis-based protein expression profiling of 16 paired tissue systems comprising clear cell renal cell carcinoma lesions and corresponding tumor-adjacent renal epithelium using overlapping narrow pH gradients. This approach led to the mapping of 348 distinct spots corresponding to 248 different protein identities. By implementing restriction criteria concerning their detection frequency and overall regulation mode, 28 up- and 56 down-regulated single target spots were considered as potential candidate biomarkers. Based on their gene ontology information, these differentially expressed proteins were classified into distinct functional groups and according to their cellular distribution. Moreover, three representative members of this group, namely calbindin, gelsolin, and heart fatty acid-binding protein, were selected, and their expression pattern was analyzed by immunohistochemistry using tissue microarrays. Thus, this pilot study provides a significant update of the current renal cell carcinoma map and defines a number of differentially expressed proteins, but both their potential as candidate biomarkers and clinical relevance has to be further explored in tissues and for body fluids like serum and urine.

Different regulation of MHC class I antigen processing components in human tumors

In recent years, progress has been made in understanding how peptides presented by MHC Class I molecules were generated, in particular which proteases are involved in this process and how intracellular pathways influence antigen presentation in professional antigen-presenting cells and various types of tumor cells. This review will give an overview of MHC Class I abnormalities in malignancies and their underlying molecular mechanisms. Dependent on the tumor types structural alterations in particular of the MHC Class I heavy chain, beta(2)-m and the TAP1 subunit have been found at a low frequency, whereas dysregulation of MHC Class I antigen processing components appears to be the major mechanism of MHC Class I down-regulation in tumors of distinct origin. This could occur at the epigenetic, transcriptional and/or post-transcriptional level. The lack or suppression of MHC Class I surface expression due to antigen-processing deficiencies are accompanied by reduced recognition and lysis by antigen-specific cytotoxic T-lymphocytes, which is further often associated with disease progression.

Combined analysis of transcriptome and proteome data as a tool for the identification of candidate biomarkers in renal cell carcinoma

Results obtained from expression profilings of renal cell carcinoma using different "ome"-based approaches and comprehensive data analysis demonstrated that proteome-based technologies and cDNA microarray analyses complement each other during the discovery phase for disease-related candidate biomarkers. The integration of the respective data revealed the uniqueness and complementarities of the different technologies. While comparative cDNA microarray analyses though restricted to up-regulated targets largely revealed genes involved in controlling gene/protein expression (19%) and signal transduction processes (13%), proteomics/PROTEOMEX-defined candidate biomarkers include enzymes of the cellular metabolism (36%), transport proteins (12%), and cell motility/structural molecules (10%). Candidate biomarkers defined by proteomics and PROTEOMEX are frequently shared, whereas the sharing rate between cDNA microarray and proteome-based profilings is limited. Putative candidate biomarkers provide insights into their cellular (dys)function and their diagnostic/prognostic value but still warrant further validation in larger patient numbers. Based on the fact that merely three candidate biomarkers were shared by all applied technologies, namely annexin A4, tubulin alpha-1A chain, and ubiquitin carboxyl-terminal hydrolase L1, the analysis at a single hierarchical level of biological regulation seems to provide only limited results thus emphasizing the importance and benefit of performing rather combinatorial screenings which can complement the standard clinical predictors.

Down-regulation of proteasomal subunit MB1 is an independent predictor of improved survival in ovarian cancer

OBJECTIVE

To investigate the expression and to determine the prognostic impact of components of the antigen processing and presentation pathway (APPP) in ovarian cancer.

METHODS

Expression of MB1, LMP7, TAP1, TAP2, ERp57, ERAP1, beta(2)-microglobulin and the alpha-chains, HLA-B/C and HLA-A, of the MHC class I molecules was evaluated on tissue microarrays containing primary tumor samples from 232 FIGO stages I-IV ovarian cancer patients. Expression levels were correlated to clinicopathological data and disease specific (DSS) survival.

RESULTS

Patients with expression of all components of the MHC class I complex, i.e. HLA-A(+)-beta(2)-m(+) and HLA-B/C(+)-beta(2)-m(+) patients, more often had expression of LMP7, a component of the immunoproteasome than patients with other phenotypes (p<0.001). These patients were also more prone to loss of MB1, part of the constitutive multicatalytic proteasome (p<0.05). Nuclear MB1 expression was an independent predictor of worse DSS (HR 1.94, 95% CI 1.16-3.26, p=0.012). The HLA-B/C(+)-beta(2)-m(+) phenotype was an independent predictor of a better prognosis (HR 0.63, 95% CI 0.40-0.99, p=0.047). Median DSS was longer for patients with normal nuclear expression of LMP7 (57.4 vs. 31.0 months, p=0.029).

CONCLUSIONS

The prognostic influence of the proteasomal subunit MB1 and the MHC class I complex in ovarian cancer provides a rationale for targeting these specific APPP components in ovarian cancer.