T-cell receptor gene expression in tumour-infiltrating lymphocytes and peripheral blood lymphocytes of patients with nasopharyngeal carcinoma

Nasopharyngeal Carcinoma and Its Microenvironment: Past, Current, and Future Perspectives

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy that raises public health concerns in endemic countries. Despite breakthroughs in therapeutic strategies, late diagnosis and drug resistance often lead to unsatisfactory clinical outcomes in NPC patients. The tumor microenvironment (TME) is a complex niche consisting of tumor-associated cells, such as fibroblasts, endothelial cells, leukocytes, that influences tumor initiation, progression, invasion, and metastasis. Cells in the TME communicate through various mechanisms, of note, exosomes, ligand-receptor interactions, cytokines and chemokines are active players in the construction of TME, characterized by an abundance of immune infiltrates with suppressed immune activities. The NPC microenvironment serves as a target-rich niche for the discovery of potential promising predictive or diagnostic biomarkers and the development of therapeutic strategies. Thus, huge efforts have been made to exploit the role of the NPC microenvironment. The whole picture of the NPC microenvironment remains to be portrayed to understand the mechanisms underlying tumor biology and implement research into clinical practice. The current review discusses the recent insights into the role of TME in the development and progression of NPC which results in different clinical outcomes of patients. Clinical interventions with the use of TME components as potential biomarkers or therapeutic targets, their challenges, and future perspectives will be introduced. This review anticipates to provide insights to the researchers for future preclinical, translational and clinical research on the NPC microenvironment.

TCR repertoire profiling of tumors, adjacent normal tissues, and peripheral blood predicts survival in nasopharyngeal carcinoma

The T-cell immune responses in nasopharyngeal carcinoma patients have been extensively investigated recently for designing adoptive immunotherapy or immune checkpoint blockade therapy. However, the distribution characteristics of T cells associated with NPC pathogenesis are largely unknown. We performed deep sequencing for TCR repertoire profiling on matched tumor/adjacent normal tissue from 15 NPC patients and peripheral blood from 39 NPC patients, 39 patients with other nasopharyngeal diseases, and 33 healthy controls. We found that a lower diversity of TCR repertoire in tumors than paired tissues or a low similarity between the paired tissues was associated with a poor prognosis in NPC. A more diverse TCR repertoire was identified in the peripheral blood of NPC patients relative to the controls; this was related to a significant decrease in the proportion of high-frequency TCR clones in NPC. Higher diversity in peripheral blood of NPC patients was associated with a worse prognosis. Due to the peculiarity of the Vβ gene usage patterns in the peripheral blood of NPC patients, 15 Vβ genes were selected to distinguish NPC patients from controls by the least absolute shrinkage and selection operator analysis. We identified 11 clonotypes shared by tumors and peripheral blood samples from different NPC patients, defined as "NPC-associated" that might have value in adoptive immunotherapy. In conclusion, we here report the systematic and overall characteristics of the TCR repertoire in tumors, adjacent normal tissues, and peripheral blood of NPC patients. The data obtained may be relevant to future clinical studies in the setting of immunotherapy for NPC patients.

Detection of monoclonal T populations in patients with KIR-restricted chronic lymphoproliferative disorder of NK cells

The etiology of chronic large granular lymphocyte proliferations is largely unknown. Although these disorders are characterized by the expansion of different cell types (T and natural killer) with specific genetic features and abnormalities, several lines of evidence suggest a common pathogenetic mechanism. According to this interpretation, we speculated that in patients with natural killer-type chronic lymphoproliferative disorder, together with natural killer cells, also T lymphocytes undergo a persistent antigenic pressure, possibly resulting in an ultimate clonal T-cell selection. To strengthen this hypothesis, we evaluated whether clonal T-cell populations were detectable in 48 patients with killer immunoglobulin-like receptor-restricted natural killer-type chronic lymphoproliferative disorder. At diagnosis, in half of the patients studied, we found a clearly defined clonal T-cell population, despite the fact that all cases presented with a well-characterized natural killer disorder. Follow-up analysis confirmed that the TCR gamma rearrangements were stable over the time period evaluated; furthermore, in 7 patients we demonstrated the appearance of a clonal T subset that progressively matures, leading to a switch between killer immunoglobulin-like receptor-restricted natural killer-type disorder to a monoclonal T-cell large granular lymphocytic leukemia. Our results support the hypothesis that a common mechanism is involved in the pathogenesis of these disorders.

HLA associations with nasopharyngeal carcinoma

Several associations have been described between the frequency of human leukocyte antigen (HLA) class I genes in certain populations and the risk of developing nasopharyngeal carcinoma (NPC). Associations between ethnic background and geographic distribution, and relative disease incidence have been reported. Populations in geographical areas at higher risk of developing NPC display HLA distribution patterns different and sometimes opposite from areas of low incidence, whereas populations in areas with intermediate incidence display a totally independent pattern. Two main reasons may explain this association between HLA phenotype distribution and the risk of developing NPC in various populations. First, given the fact that expression of Epstein-Barr Virus (EBV) proteins by cancer cells is tightly linked with NPC development, HLA may influence the development of NPC by modulating the expression of EBV proteins. This explanation is, however, based primarily on theoretical assumptions given that no clear definition of HLA binding pattern of EBV epitopes has been directly shown to significantly alter the recognition of EBV proteins and the risk of developing the disease. Alternatively, HLA may represent a genetic marker flagging the presence of a NPC predisposition locus in close linkage disequilibrium with the HLA class I region. A critical review of known HLA associations in various geographical areas and their interpretation will be presented in this review.

Peripheral gamma delta T-cell deficit in nasopharyngeal carcinoma

Previous studies identified CD56(+) and CD56(-) subsets of peripheral gamma delta T cells from healthy donors. Both subsets responded to stimulation by a myeloma cell line, XG-7 and undergo vigorous ex vivo expansion in the presence of exogenous IL-2. They are cytotoxic for different tumor targets including nasopharyngeal carcinoma, but they differ from one another in that the CD56(-) subset has an additional growth requirement for IL-7 and exhibited greater cytotoxicity against nasopharyngeal carcinoma (NPC) targets. These immune cells were further shown to retard tumor growth in a nude mice NPC model. To assess if these immune cells might contribute to host defense against NPC, we compared gamma delta T-cell status of NPC patients with healthy donors and survivors who had been in clinical remission of the cancer. It was found that peripheral gamma delta T cells of patients were impaired in their response to the stimulatory effects of XG-7 and exhibited weak or essentially no cytotoxicity for the NPC targets. The deficits were present in early and advanced stages of the cancer but were restored among survivors after successful treatment of the cancer. These findings support a role for peripheral gamma delta T cells in host defense against NPC. It was noted that these immune cells comprise less than 5% of peripheral blood monocytic cells and hence it was not surprising that this component of host defense was breached early in the development of the cancer.

Lymphoid cell infiltration into Epstein-Barr virus-positive nasopharyngeal carcinomas

OBJECTIVES

A pilot study was designed to analyze lymphoid cell infiltration in Epstein-Barr virus-positive (EBV+) nasopharyngeal carcinomas (NPCs) and to determine whether this pattern of infiltration is consistent with non-EBV+ head and neck carcinomas or with solid EBV+ tumors in other locations.

STUDY DESIGN

We performed a retrospective analysis of archived NPCs and oral cavity carcinomas.

METHODS

Immunohistochemical staining of the archive material for various markers (CD3, CD8, UCHL-1, S-100, and intercellular adhesion molecule) was performed. Polymerase chain reaction techniques to establish the presence of the EBV genome were used. Cells in different locations were counted under a light microscope by 2 of the authors.

RESULTS

The infiltration pattern of NPCs was different from that of oral cavity carcinomas. Stromal infiltration was significantly denser in oral cavity carcinomas. Tumor nest infiltration was more pronounced in NPCs. The pattern of infiltration was comparable with what has been described for other solid EBV+ tumors.

CONCLUSIONS

The immune response to NPCs is likely to be strongly influenced by the presence of the EBV genome. The pattern of infiltration is similar to that of other non-head and neck EBV+ solid tumors and different from that of EBV- head and neck carcinomas.

Diagnostic usefulness of telomerase activity in nasopharyngeal carcinoma

Telomeres are specialized structures at the ends of eukaryotic chromosomes which are composed of simple repetitive G-rich hexameric sequences. Activation of telomerase, a ribonucleoprotein that synthesizes telomeric DNA, is found in most malignant tumors. However, little data is available concerning the correlation between telomerase activity and NPC (nasopharyngeal carcinoma). In this study, telomerase activation was determined using the TRAP (telomerase repeat amplification protocol) assay in 62 nasopharyngeal biopsies (25 NPC, 25 non-malignant nasopharyngeal lymphoid tissues, 12 post-irradiated nasopharyngeal tissues). The results showed that strong telomerase activity was present in both NPC and non-malignant nasopharyngeal biopsies. Post-irradiated nasopharyngeal samples had a significantly lower telomerase activity than NPC and non-malignant nasopharyngeal lymphoid tissues. It is well known that nasopharyngeal tissue is infiltrated by numerous lymphocytes, which might retain telomerase activity. Therefore, the finding that the telomerase activation was lowest in post-irradiated nasopharyngeal tissues is reasonable because of the destruction of activated lymphocytes and NPC by radiation. NPC biopsies with positive lymph node involvement exhibited higher levels of telomerase compared to those without lymph node involvement. Our data indicate a positive association between telomerase activity and tumor potential for lymphatic spreading in limited local tumors. In addition, telomerase activity may be useful as a diagnostic marker in the detection of tumor cells in recurrent NPC, but not in primary NPC.