Assessment of cancer cell-expressed HLA class I molecules and their immunopathological implications

Immunotherapy using immune checkpoint inhibitors (ICIs) has shown superior efficacy compared with conventional chemotherapy in certain cancer types, establishing immunotherapy as the fourth standard treatment alongside surgical intervention, chemotherapy, and radiotherapy. In cancer immunotherapy employing ICIs, CD8-positive cytotoxic T lymphocytes are recognized as the primary effector cells. For effective clinical outcomes, it is essential that the targeted cancer cells express HLA class I molecules to present antigenic peptides derived from the tumor. However, cancer cells utilize various mechanisms to downregulate or lose HLA class I molecules from their surface, resulting in evasion from immune surveillance. Correlations between prognosis and the integrity of HLA class I molecules expressed by cancer cells have been consistently found across different types of cancer. This paper provides an overview of the regulatory mechanisms of HLA class I molecules and their role in cancer immunotherapy, with a particular emphasis on the significance of utilizing pathological tissues to evaluate HLA class I molecules expressed in cancer cells.

The prognostic value of TCF1+CD8+T in primary small cell carcinoma of the esophagus

TCF1+CD8+T cells are reported to exhibit stem-like properties with the ability to self-renew and differentiate into terminal effector T cells (TCF1-CD8+T cells) to enhance antitumor response. Previous studies indicated that TCF1+CD8+ tumor-infiltrating lymphocytes (TILs) are related to response to immunotherapy. However, their role in predicting prognosis for patients with primary small cell carcinoma of the esophagus (PSCCE) remains unclear. In this study, the expression of TCF1+CD8+T was analyzed by multiplex fluorescence immunohistochemistry in tumor tissues of 79 patients with PSCCE. High infiltration of TCF1+CD8+T cells had longer overall survival (OS) than low infiltration (P = .009, hazard ratio [HR] = 0.506). High TCF1+CD8/CD8 ratio (>21%) showed superior OS compared with low ratio (≤21%) (P < .001, HR = 0.394). In the validation set (n = 20), the prognostic value of TCF1+CD8+T cells on OS was also verified. TCF1+CD8+T cells are strong prognostic predictors.

B4GALNT2 Gene Promotes Proliferation, and Invasiveness and Migration Abilities of Model Triple Negative Breast Cancer (TNBC) Cells by Interacting With HLA-B Protein

B4GALNT2 gene encodes the enzyme β1,4-N-acetylgalactosaminyltransferase 2 that biosynthesizes the histo-blood group antigen Sda, which is expressed on the surface of erythrocytes and in body secretions. Analysis of The Cancer Genome Atlas (TCGA) database revealed that this gene was highly expressed in breast cancer tissues in comparison with adjacent healthy ones. In-vitro lentivirus-assisted B4GALNT2 gene knockdown experiments in model triple negative breast cancer (TNBC) cell lines (HCC1937 and MDA-MB-231) showed inhibition in cell proliferation, decrease in cell viability, promotion of cell apoptosis and inhibitions in cell migration and invasiveness abilities in comparison with empty lentivirus transfectant controls. Also, in cell cycle tests, the number of cells in the G1 phase increased, in the S phase decreased and did not change in the G2/M phase (indicative of the presence of a block in the G1 phase). In-vivo tumor formation experiments in mice revealed that knockdown of the B4GALNT2 gene in MDA-MB-231 cells inhibited their proliferation. Using co-immunoprecipitation (Co-IP) mass spectroscopy-assisted analysis, it was found that HLA-B protein [a product of the human leukocyte antigen (HLA) class I gene] interacts with B4GALNT2 protein. In-vitro overexpression of HLA-B in B4GALNT2-knocked down MDA-MB-231 cell lines significantly recovered the cell proliferation, viability and migration ability of B4GALNT2 gene. These indicate that HLA-B is one of the interaction proteins in the downstream pathway of the B4GALNT2 gene.

Human leukocyte antigen class II-based immune risk model for recurrence evaluation in stage I-III small cell lung cancer

Background

Immunotherapy has revolutionized therapeutic patterns of small cell lung cancer (SCLC). Human leukocyte antigen class II (HLA class II) is related to antitumor immunity. However, the implications of HLA class II in SCLC remain incompletely understood.

Materials and methods

We investigated the expression patterns of HLA class II on tumor cells and tumor-infiltrating lymphocytes (TILs) by immunohistochemistry staining and its association with clinical parameters, immune markers, and recurrence-free survival (RFS) in 102 patients with stage I–III SCLC with radical surgery. Additionally, an HLA class II-based immune risk model was established by least absolute shrinkage and selection operator regression. With bioinformatics methods, we investigated HLA class II-related enrichment pathways and immune infiltration landscape in SCLC.

Results

HLA class II on tumor cells and TILs was positively expressed in 9 (8.8%) and 45 (44.1%) patients with SCLC, respectively. HLA class II on TILs was negatively associated with lymph node metastasis and positively correlated with programmed death-ligand 1 (PD-L1) on TILs (p<0.001) and multiple immune markers (CD3, CD4, CD8, FOXP3; p<0.001). Lymph node metastasis (OR 0.314, 95% CI 0.118 to 0.838, p=0.021) and PD-L1 on TILs (OR 3.233, 95% CI 1.051 to 9.95, p=0.041) were independent predictive factors of HLA class II on TILs. HLA class II positivity on TILs prompted a longer RFS (40.2 months, 95% CI 31.7 to 48.7 vs 28.8 months, 95% CI 21.4 to 36.3, p=0.014). HLA class II on TILs, PD-L1 on TILs, CD4, and FOXP3 were enrolled in the immune risk model, which categorized patients into high-risk and low-risk groups and had better power for predicting the recurrence than tumor stage. Pathway enrichment analyses showed that patients with high HLA class II expression demonstrated signatures of transmembrane transportation, channel activity, and neuroactive ligand–receptor interaction. High-risk SCLC patients had a higher proportion of T follicular helper cells (p=0.034) and a lower proportion of activated memory CD4-positive T cells (p=0.040) and resting dendritic cells (p=0.045) versus low-risk patients.

Conclusions

HLA class II plays a crucial role in tumor immune microenvironment and recurrence prediction. This work demonstrates the prognostic and clinical values of HLA class II in patients with SCLC.

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.

Expression of human leukocyte antigen class I and β2-microglobulin in colorectal cancer and its prognostic impact

Downregulation of human leukocyte antigen (HLA) class I has been postulated to be a mechanism of adaptive immune escape in various tumors, especially microsatellite instability-high (MSI-H) colorectal cancer (CRC). In this study, we aimed to investigate HLA class I and β2-microglobulin (β2M) expression in MSI-H and microsatellite-stable (MSS) CRCs and determine its prognostic impact. The representative areas from the tumor center (TC) and tumor periphery (TP) from 300 CRCs, including 161 MSI-H and 139 MSS cases, were selected to construct a tissue microarray. Immunohistochemistry (IHC) for HLA A/B/C, β2M, CD3, and CD8 was performed. Reduced HLA A/B/C expression was detected in 113 (70.2%) MSI-H and 54 (38.8%) MSS cases, while reduced β2M expression was observed in 69 (42.9%) MSI-H and 17 (12.2%) MSS cases. Although reduced β2M expression was associated with higher pathological tumor (pT) stage in MSI-H CRC with borderline significance, no association was found between HLA A/B/C and β2M expression and survival. Interestingly, reduced HLA A/B/C expression in MSS was associated with higher stage, and reduced HLA A/B/C and β2M expression was an independent prognostic factor in multivariate analysis. In conclusion, reduced HLA A/B/C and β2M expression was frequently observed in immunotherapy-naive MSI-H CRC, suggesting the possibility of primary resistance to immune checkpoint inhibitor. Interestingly, downregulation of HLA A/B/C and β2M was associated with poor prognosis in MSS cancers. Overall, IHC for HLA A/B/C and β2M might be a feasible predictive or prognostic tool in CRC.

HLA-B influences integrin beta-1 expression and pancreatic cancer cell migration

Human leukocyte antigen (HLA) class I molecules present antigenic peptides to cytotoxic T cells, causing lysis of malignant cells. Transplantation biology studies have implicated HLA class I molecules in cell migration, but there has been little evidence presented that they influence cancer cell migration, a contributing factor in metastasis. In this study, we examined the effect of HLA-B on pancreatic cancer cell migration. HLA-B siRNA transfection increased the migration of the S2-013 pancreatic cancer cells but, in contrast, reduced migration of the PANC-1 and MIA PaCa-2 pancreatic cancer cell lines. Integrin molecules have previously been implicated in the upregulation of pancreatic cancer cell migration, and knockdown of HLA-B in S2-013 cells heightened the expression of integrin beta 1 (ITGB1), but in the PANC-1 and MIA PaCa-2 cells HLA-B knockdown diminished ITGB1 expression. A transmembrane sequence in an S2-013 HLA-B heavy chain matches a corresponding sequence in HLA-B in the BxPC-3 pancreatic cancer cell line, and knockdown of BxPC-3 HLA-B mimics the effect of S2-013 HLA-B knockdown on migration. In total, our findings indicate that HLA-B influences the expression of ITGB1 in pancreatic cancer cells, with concurrent distinctions in transmembrane sequences and effects on the migration of the cells.

Clinicopathologic significance of human leukocyte antigen class I expression in patients with stage II and III gastric cancer

Human leukocyte antigen class I (HLA I) molecules composed of alpha (heavy) chain, including HLA-A, -B, or -C encoded by HLA genes, and beta-2-microglobulin (β2M) are membrane proteins on all nucleated cells that display peptide antigens for recognition by CD8-positive cytotoxic T cells. Here, we examined the clinicopathologic signification of HLA I expression in patients with gastric cancer (GC). Immunohistochemistry was performed to detect HLA A/B/C, β2M, CD8, p53, and programmed death-ligand 1 (PD-L1) in the center and invasive margin of the tumor in 395 stage II and III GCs using tissue array method. Additionally, Epstein-Barr virus (EBV) infection and microsatellite instability (MSI) status were investigated. Negative expression of HLA A/B/C and β2M was observed in 258 (65.3%) and 235 (59.5%) of 395 stage II and III GCs, respectively. Negative HLA I expression was significantly associated with aggressive clinicopathologic features. Furthermore, negative expression of HLA A/B/C and β2M was inversely correlated with CD8-positive cytotoxic T cell infiltration, EBV-positivity, and PD-L1 expression (all p < 0.001). Patients with HLA A/B/C-negative GC had worse overall survival (OS) (p = 0.019) and combined analysis with both HLA A/B/C and β2M expression status significantly predicted OS in univariate (p = 0.004) and multivariate survival analysis (p = 0.016). Negative expression of HLA A/B/C and β2M was frequently observed in stage II and III GCs, particularly with the aggressive clinicopathologic features, and correlated with an unfavorable prognosis and host immune response status. These findings contribute to further development of immunotherapy.

Human Leukocyte Antigen Class I and Programmed Death-Ligand 1 Coexpression Is an Independent Poor Prognostic Factor in Adenocarcinoma of the Lung

Background

Both human leukocyte antigen (HLA) class I and programmed death-ligand 1 (PD-L1) molecules are known to play important roles in cancer immunity. In this study, we evaluated HLA class I expression in resected adenocarcinoma of the lung, and investigated its prognostic impact in correlation with PD-L1 expression.

Methods

HLA class I and PD-L1 expression was evaluated by immunohistochemistry in a total of 403 resected lung adenocarcinomas using tissue microarray. Correlations between the expression of HLA class I/PD-L1 and clinicopathologic features and prognostic significance were analyzed.

Results

HLA class I expression was reduced in 91.6% of adenocarcinoma, and more frequently reduced in patients with younger age, absence of vascular invasion, and low pathologic stage (p = .033, p = .007, and p = .012, respectively). Positive PD-L1 expression in tumor cells was 16.1% (1% cut-off), and associated with poor differentiation, presence of vascular invasion and nodal metastasis (p < .001, p = .002, and p = .032, respectively). On survival analysis, HLA class I or PD-L1 expression alone did not show any statistical significance. On the integrated analysis, HLA class I (+)/PD-L1 (+) subgroup showed a significantly shorter overall survival than other groups (p = .001). Multivariate analysis revealed that coexpression of HLA class I and PD-L1 was an independent poor prognostic factor of lung adenocarcinoma. (p < .001; hazard ratio, 6.106; 95% confidence interval, 2.260 to 16.501).

Conclusions

Lung adenocarcinoma with coexpression of HLA class I and PD-L1 was associated with poor prognosis. This subgroup may evade immune attack by expressing PD-L1 protein despite HLA expression.

Expression of PD-L1 and HLA Class I in Esophageal Squamous Cell Carcinoma: Prognostic Factors for Patient Outcome

BACKGROUND

Programmed cell death 1 ligand 1 (PD-L1) and human leukocyte antigen (HLA) class I molecules on malignant cell surfaces are pivotal for tumor immunity. The clinical significance of their expression in patients with esophageal squamous cell carcinoma (ESCC) remains to be determined.

METHODS

PD-L1 and HLA class I protein expression was investigated by immunohistochemical staining of resected specimens from 90 ESCC patients who underwent radical surgery without preoperative therapy. The relationships between the expression of PD-L1 and HLA class I and clinicopathologic factors and patient prognosis were assessed.

RESULTS

High expression of PD-L1 and HLA class I were observed in 17 (18.9 %) and 35 (38.9 %) of 90 cases, respectively. High PD-L1 expression was correlated with the depth of tumor invasion (P = 0.0379), lymph node metastasis (P = 0.0031), recurrence (P = 0.0085), and poor overall survival (OS) (5-year survival rate; low/high: 60.9/28.4 %, P = 0.0110). Among those patients with high expression of HLA class I, high PD-L1 expression was correlated with significantly poorer recurrence-free survival (median survival time, low/high: 102.5/3.1 months, P = 0.0016) and poorer OS (median survival time, low/high: 102.5/13.1 months, P = 0.0027). Multivariate analysis showed that combined high PD-L1/high HLA class I expression was an independent prognostic factor for recurrence-free survival (hazard ratio 2.88, 95 % confidence interval 1.02-7.04, P = 0.0455) and OS (hazard ratio 2.95, 95 % confidence interval 1.03-7.50, P = 0.0447).

CONCLUSIONS

High PD-L1 expression was a significant independent prognostic factor in ESCC patients with high HLA class I expression.

Clinical implications of human leukocyte antigen class I expression in endometrial cancer

Decreased expression of human leukocyte antigen (HLA) class I molecules, which is found in several types of cancer, is associated with worse clinical prognosis in cancer patients. The present study was undertaken to investigate the association of immunohistochemical HLA class I expression patterns with clinicopathological factors and prognosis in 96 endometrial cancer patients. HLA class I is composed of a heavy chain (HC-10) and a β2-microglobulin (β2-m) light chain. The HLA class I expression patterns were classified as positive when both HC-10 and β2-m were strongly stained and negative in all other cases. The negative staining pattern was associated with advanced International Federation of Gynecology and Obstetrics stage (P<0.001), lymphovascular space involvement (LVSI) (P=0.003) and lymph node metastasis (P=0.005). Moreover, these cases exhibited worse progression-free survival (PFS) and overall survival (OS) rates compared with positive cases (P=0.005 and P=0.014, respectively). However, the multivariate analysis did not identify HLA class I expression as an independent predictive factor for PFS and OS. In conclusion, HLA class I expression may be useful for predicting postoperative outcome in endometrial cancer, as well as well-known predictive prognostic factors, such as lymph node metastasis and LVSI.

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.

Lesion HLA-F expression is irrelevant to prognosis for patients with gastric cancer

Alteration of human leukocyte antigen (HLA) antigen expression has been supposed to play critical roles in progression of malignancies. However, clinical significance of the non-classical HLA class I antigen HLA-F remains largely unknown. In this study, HLA-F expression in 277 primary gastric cancer (GC) lesions was analyzed by immunohistochemistry. Data revealed that HLA-F expression was observed in 71.1% (197/277) of the GC lesions. Lesion HLA-F expression was unrelated to the clinicoparameters such as gender, age, depth of tumor invasion and disease stage. Survival analysis revealed that HLA-F expression in GC lesion was unrelated to patient prognosis (p=0.190). The mean overall survival time (MOS) for lesion HLA-F negative and positive patients was 11.3 months (95% CI: 9.3-13.3) and 13.9 months (95% CI: 10.5-17.3), respectively. In conclusion, our study provided the evidence that HLA-F expression was unrelated to prognosis for patients with gastric cancer.

HLA class I: an unexpected role in integrin β4 signaling in endothelial cells

The production of anti-donor antibodies to HLA class I and class II antigens following transplantation is associated with development of transplant vasculopathy and graft loss. Antibodies against HLA class I (HLA-I) molecules are thought to contribute to transplant vasculopathy by triggering signals that elicit the activation and proliferation of endothelial cells. The proximal molecular events that regulate HLA-I dependent signal transduction are not well understood. We demonstrated a mutual dependency between HLA-I and integrin β4 to stimulate signal transduction and cell proliferation. Similarly, we found that integrin β4-mediated cell migration was dependent upon its interactions with HLA-I molecules. Since integrin β4 has been implicated in angiogenesis and tumor formation, associations between integrin β4 and HLA-I may play an important role in cancer. Further characterization of interactions between HLA-I and integrin β4 may lead to the development of therapeutic strategies for the treatment and prevention of chronic allograft rejection and cancer.

The bodies fight against cancer: is human leucocyte antigen (HLA) class 1 the key?

INTRODUCTION

Loss of human leucocyte antigen (HLA) class I expression has been implicated in tumour progression and metastasis; however, studies reporting its relationship with long-term survival are few in number with conflicting reports. The aim of this review was to assess the prognostic value of HLA class I expression in gastrointestinal cancer.

METHODS

Major electronic databases, including Medline, Embase, Cochrane Library and Pubmed were searched for original studies. Two independent reviewers assessed each study against inclusion and exclusion criteria. All data were specific to gastrointestinal cancer surgery.

RESULTS

Fourteen original studies were included in this present review. In oesophageal cancer, reduced expression of HLA-A, HLA-B, HLA-C and HLA-G were associated with poorer survival. However, in gastric and colorectal cancer, the prognostic value of HLA-A, HLA-B, HLA-C and HLA-G remains conflicting. Antibody use and reporting methodology was different between all 14 studies examined.

CONCLUSION

Variability in antibody use makes it difficult to validate HLA class I expression as an independent prognostic marker in GI cancer. Consensus guidelines, incorporating heavy and light chain antibodies, are required with further studies on HLA class I expression being performed to validate its prognostic value.

Prognostic significance of HLA class I expressing in gastric carcinoma defined by monoclonal anti-pan HLA class I antibody, EMR8-5

INTRODUCTION

Downregulation or loss of HLA class I molecules has been demonstrated in human cancers. The aim of this study was to assess the clinical significance of HLA class I expression in gastric cancer.

METHODS

Gastric cancer tissues from 189 patients were examined for expression of HLA class I heavy chain antigens by immunohistochemical staining with EMR8-5. The expression level of HLA class I of tumor cells is categorized by combining an estimate the percentage of immunoreactive cell with an estimate of the staining intensity. The relationship between HLA class I expression and clinicopathologic parameters, patient survival, and tumor recurrence were analyzed.

RESULTS

HLA class I was downregulated in 85 (45.0%) of the gastric carcinomas. Staining revealed 104 (55.0%) tumors with strongly positive expression of HLA class I antigens, 76 (40.2%) tumors with weakly positive expression, and 9 (4.8%) tumors with negative expression. The expression of HLA class I antigen did not correlate with any other clinicopathologic parameters. Moreover, HLA class I expression was neither a risk factor for tumor recurrence nor survival.

CONCLUSION

The downregulation of HLA class I expression is not associated with patient prognosis.

HLA class I molecules partner with integrin β4 to stimulate endothelial cell proliferation and migration

Among transplant recipients, those who produce antibodies against the donor's human leukocyte antigens (HLAs) are at higher risk for antibody-mediated rejection and transplant vasculopathy, which is a progressive, vasculo-occlusive disease that results in ischemic injury and deterioration of organ function. Antibodies against HLA class I (HLA-I) molecules are thought to contribute to transplant vasculopathy by triggering signals that elicit the activation and proliferation of endothelial cells. Here, we demonstrate a molecular association between HLA-I and the integrin β(4) subunit after the stimulation of endothelial cells with HLA-I-specific antibodies. Knockdown of integrin β(4) in these cells abrogated the ability of HLA-I to stimulate the phosphorylation of the kinases Akt, extracellular signal-regulated kinase (ERK), and Src, as well as cellular proliferation. Similarly, reducing the abundance of HLA-I suppressed integrin β(4)-mediated phosphorylation of ERK and the migration of endothelial cells on laminin-5, a component of the extracellular matrix. These results indicate a mutual dependency between HLA-I and the integrin β(4) subunit to stimulate the proliferation and migration of endothelial cells, which may be important in promoting transplant vasculopathy and tumor angiogenesis.

Hypermethylation of HLA class I gene is associated with HLA class I down-regulation in human gastric cancer

Down-regulated expression of human leukocyte antigen (HLA) class I molecules in many human cancers facilitate tumor cells to escape from immune attack. Promoter hypermethylation, one of the major epigenetic changes responsible for gene inactivation, plays an important role in gastric carcinogenesis. This study evaluated the expression and alteration of HLA class I molecules in a panel of 47 pairs of gastric cancer specimens with their noncancerous parts from Chinese patients by using immunohistochemistry (IHC), reverse transcription polymerase chain reaction (RT-PCR) and methylation-specific PCR (MSP) analysis. The expression of HLA-A, HLA-B/C and HLA class I complex was lost or down-regulated in human gastric cancer. The percentage of promoter methylation was 59.57% for HLA-A gene, 55.32% for HLA-B gene and 48.94% for HLA-C gene in gastric cancer, while it was decreased to 19.15%, 12.77% and 6.38% in the adjacent nontumor tissues, respectively. Seven of 10 (70%), 4 of 6 (66.7%) and 3 of 4 (75%) gastric cancer specimens with promoter hypermethylation at HLA-A, -B and -C loci showed transcriptional inactivation of HLA-A,-B and -C genes, suggesting an association between promoter hypermethylation and down-regulated expression of HLA class I molecules. Human gastric cancer cell line BGC-823 showed HLA-A down-regulation with promoter methylation of HLA-A locus. Treatment with DNA methyltransferase inhibitor restored the expression of HLA-A mRNA and surface HLA-A complex. Thus, our results showed that promoter hypermethylation might be one of the mechanisms that lead to HLA class I antigen down-regulation in gastric cancer.

Downregulation of HLA Class I molecules in the tumour is associated with a poor prognosis in patients with oesophageal squamous cell carcinoma

As antigenic peptides in the context of human leukocyte antigen (HLA) class I molecules are recognised by cytotoxic T lymphocytes (CTL), the downregulation of HLA class I molecules is one of the reasons why tumour cells can evade CTL-mediated anti-tumour immunity. In this study, we investigated HLA class I expression in oesophageal squamous cell carcinoma (ESCC) (n=70) and in their metastatic lesions (lymph nodes (n=40) and liver (n=3)), by immunohistochemistry with anti-HLA class I monoclonal antibody (EMR8-5). As a result, the downregulation of HLA class I expression in primary lesions of ESCC was observed in 43%, and that in metastatic lymph nodes was noted in 90%. Furthermore, patients with preserved HLA class I expression in primary tumours showed a better survival in comparison to those with downregulated HLA class I molecules (P<0.01). Furthermore, multivariate analysis using Cox's proportional hazards model revealed that the downregulated expression of HLA class I in primary lesions was an independent, unfavourable prognostic factor (P<0.01). In conclusion, the downregulation of HLA class I expression frequently occurred in primary tumour and, to a greater extent, in metastatic lesions of patients with ESCC and was associated with patient survival.