Koichi Sakakura

Immunosuppressive activity of CD14+ HLA-DR- cells in squamous cell carcinoma of the head and neck.

Myeloid‐derived suppressor cells (MDSC) represent a heterogeneous population and have the potential to suppress immune responses via diverse mechanisms. In recent studies, a new subset of MDSC was identified by the markers CD14+ and HLA‐DR− in the peripheral blood from cancer patients. In this study, we investigated the proportions and characteristics of CD14+ HLA‐DR− cells in patients with squamous cell carcinoma of the head and neck (SCCHN). As expected, the percentage of CD14+ HLA‐DR− cells was significantly elevated in patients relative to healthy donors and the sorted CD14+ HLA‐DR− cells were able to suppress effectively both the proliferation and IFN‐γ production of anti‐CD3/anti‐CD28 stimulated T cells, suggesting that CD14+ HLA‐DR− cells in patients with SCCHN contribute to the immune suppressive status. Furthermore, CD14+ HLA‐DR− cells revealed a higher level of CD86 and PD‐L1 expression and transforming growth factor (TGF)‐β production than CD14+ HLA‐DR+ cells. Addition of anti‐CD86 mAb, anti‐PD‐L1 mAb and anti‐TGF‐β mAb partially restored T‐cell proliferation and IFN‐γ production, respectively, indicating that the suppressive effects of CD14+ HLA‐DR− cells appear to be mediated by various molecules, including coinhibitory molecules and cytokines. Our data suggest that CD14+ HLA‐DR− cells act as potent immunosuppressive cells and particularly contribute to tumor escape from the host immune system in patients with SCCHN. (Cancer Sci 2012; 103: 976–983)

Maturation of circulating dendritic cells and imbalance of T-cell subsets in patients with squamous cell carcinoma of the head and neck

Interactions between dendritic cells (DCs) and T cells play a pivotal role in the regulation and maintenance of immune responses. In cancer patients, various immunological abnormalities have been observed in these immune cells. Here, we investigated proportions and the phenotype of DCs and the cytokine profile of T-cell subsets in the peripheral blood of patients with squamous cell carcinoma of the head and neck (SCCHN), using multicolor flow cytometry. The percentage of myeloid (CD11c+), but not plasmacytoid (CD123+) DCs, was significantly lower (P<0.05) and expression of HLA-DR was significantly decreased in total and myeloid DCs of cancer patients compared to healthy donors. Simultaneous analyses of T-cell subsets in the patients’ circulation showed significantly increased proportions of CD4+ T cells expressing Th1 and Th2 cytokines after ex vivo stimulation without any skewing in the Th1/Th2 ratio. The relative level of HLA-DR expression on myeloid or total DCs positively correlated with the Th1/Th2 ratio (P<0.01), and the proportion of total circulating DCs was inversely correlated with that of regulatory CD4+CD25+ T cells (P<0.01). These results suggest that the decreased proportion of circulating DCs and decreased HLA-DR expression in DCs may have a major impact on systemic immune responses in patients with SCCHN.

Resistance to apoptosis-inducing stimuli in CD44+ head and neck squamous cell carcinoma cells.

CD44 was identified previously as a surface marker in cancer stem cells (CSCs) of head and neck squamous cell carcinoma (HNSCC). Most cancer treatments have been linked to the activation of the apoptosis‐signaling pathway; however, the resistance mechanisms to apoptosis in CSCs have not yet been fully elucidated.

Functional Characterization of an scFv-Fc Antibody that Immunotherapeutically Targets the Common Cancer Cell Surface Proteoglycan CSPG4

Cell surface chondroitin sulfate proteoglycan 4 (CSPG4) is an attractive target for antibody-based cancer immunotherapy because of its role in tumor cell biology, its high expression on malignant cells including cancer-initiating cells, and its restricted distribution in normal tissues. The clinical use of CSPG4 has been hampered by the lack of a CSPG4-specific chimeric, humanized, or fully human monoclonal antibody. To overcome this limitation, we generated a CSPG4-specific fully human single-chain antibody termed scFv-FcC21 and characterized its specificity and antitumor activity. Viable CSPG4(+) melanoma cells were used in a screen of a human scFv phage display library that included CDR3 engineered to optimize antibody binding sites. The scFv antibody isolated was then recombinantly engineered with a human immunoglobulin G1 Fc region to construct the fully human antibody scFv-FcC21, which recognized tumors of neuroectodermal origin, various types of carcinomas, mesotheliomas, and sarcomas as well as myeloid leukemias. scFv-FcC21 inhibited in vitro growth and migration of tumor cells and in vivo growth of human tumor xenografts. These effects were mediated by inhibition of the activation of extracellular signal-regulated kinase and focal adhesion kinase signaling pathways that are critical for tumor cell growth and migration, respectively. Our findings define the CSPG4-specific fully human scFv-FcC21 antibody as a candidate therapeutic agent to target the many types of tumors that express CSPG4.

Prognostic significance of amino-acid transporter expression (LAT1, ASCT2, and xCT) in surgically resected tongue cancer.

Background:Amino-acid transporters are necessary for the tumour cell growth and survival, and have a crucial role in the development and invasiveness of cancer cells. But, it remains unclear about the prognostic significance of L-type amino-acid transporter 1 (LAT1), system ASC amino-acid transporter-2 (ASCT2), and xCT expression in patients with tongue cancer. We conducted the clinicopathological study to investigate the protein expression of these amino-acid transporters in tongue cancer.Methods:Eighty-five patients with surgically resected tongue cancer were evaluated. Tumour sections were stained by immunohistochemistry for LAT1, ASCT2, xCT, 4F2hc/CD98hc (4F2hc), Ki-67, and microvessel density (MVD) determined by CD34, and p53.Results:L-type amino-acid transporter 1 and 4F2hc were highly expressed in 61% (52 out of 85) and 45% (38 out of 47), respectively. ASC amino-acid transporter-2 and xCT were positively expressed in 59% (50 out of 85) and 21% (18 out of 85), respectively. The expression of both LAT1 and ASCT2 was significantly associated with disease staging, lymph-node metastasis, lymphatic permeation, 4F2hc expression and cell proliferation (Ki-67). xCT expression indicated a significant association with advanced stage and tumour factor. By univariate analysis, disease staging, lymphatic permeation, vascular invasion, LAT1, ASCT2, 4F2hc, and Ki-67 had a significant relationship with overall survival. Multivariate analysis confirmed that LAT1 was an independent prognostic factor for predicting poor prognosis.Conclusions:L-type amino-acid transporter 1 and ASCT2 can serve as a significant prognostic factor for predicting worse outcome after surgical treatment and may have an important role in the development and aggressiveness of tongue cancer.

Primary tumor induces sentinel lymph node lymphangiogenesis in oral squamous cell carcinoma

The main factor that affects the prognosis of patients with oral squamous cell carcinoma (OSCC) is regional lymph node metastases, which usually spreads first to the sentinel lymph nodes (SLNs). Recent studies have demonstrated that tumor cells in several malignancies can induce lymphangiogenesis in SLNs before metastasizing. To elucidate the mechanisms of tumor dissemination of OSCC, we investigated whether primary tumors induce lymphangiogenesis within SLNs in patients with OSCC. The mRNA expression of lymphatic-specific markers, including VEGFR-3, Prox-1, and LYVE-1 in 23 metastasis-negative SLNs obtained from 10 patients with OSCC, was investigated using a quantitative real-time RT-PCR assay, and compared with control lymph nodes from patients with non-cancerous diseases. In addition, VEGF-C and VEGF-D expressions of the primary tumor were examined by immunohistochemistry. In SLNs, there were highly significant correlations between the three lymphatic markers examined. Interestingly, the level of LYVE-1 expression in SLNs, despite the absence of metastasis, was significantly higher than in control lymph nodes. Moreover, SLNs from patients with VEGF-C-positive tumor showed a significantly higher expression of VEGFR-3 than those from patients with VEGF-C-negative tumor. Our findings suggest that in OSCC, the primary tumor actively induces lymphangiogenesis in SLNs prior to the onset of metastases, and where tumor-derived VEGF-C plays an important role.

Alteration of cancer stem cell‐like phenotype by histone deacetylase inhibitors in squamous cell carcinoma of the head and neck

Recent progression in the understanding of stem cell biology has greatly facilitated the identification and characterization of cancer stem cells (CSCs). Moreover, evidence has accumulated indicating that conventional cancer treatments are potentially ineffective against CSCs. Histone deacetylase inhibitors (HDACi) have multiple biologic effects consequent to alterations in the patterns of acetylation of histones and are a promising new group of anticancer agents. In this study, we investigated the effects of two HDACi, suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA), on two CD44+ cancer stem‐like cell lines from squamous cell carcinoma of the head and neck (SCCHN) cultured in serum‐free medium containing epidermal growth factor and basic fibroblast growth factor. Histone deacetylase inhibitors inhibited the growth of SCCHN cell lines in a dose‐dependent manner as measured by MTS assays. Moreover, HDACi induced cell cycle arrest and apoptosis in these SCCHN cell lines. Interestingly, the expression of cancer stem cell markers, CD44 and ABCG2, on SCCHN cell lines was decreased by HDACi treatment. In addition, HDACi decreased mRNA expression levels of stemness‐related genes and suppressed the epithelial‐mesencymal transition phenotype of CSCs. As expected, the combination of HDACi and chemotherapeutic agents, including cisplatin and docetaxel, had a synergistic effect on SCCHN cell lines. Taken together, our data indicate that HDACi not only inhibit the growth of SCCHN cell lines by inducing apoptosis and cell cycle arrest, but also alter the cancer stem cell phenotype in SCCHN, raising the possibility that HDACi may have therapeutic potential for cancer stem cells of SCCHN.

Immunological significance of the accumulation of autophagy components in oral squamous cell carcinoma

The immunological significance of autophagy in the tumor microenvironment remains unclear. To explore the relationship between autophagy and anti‐tumor immune responses, we investigated the expression of autophagy‐related proteins and infiltration of immune cells using immunohistochemistry (IHC). The expression of three representative autophagy components, LC3, Beclin‐1 and p62/SQSTM1, as well as the number of dendritic cells (DC), T cells and NK cells were examined by IHC in 74 patients with oral squamous cell carcinoma (OSCC). The relationship between the expression of autophagy‐associated molecules and various clinicopathological parameters was also evaluated. The expression of both LC3 and p62/SQSTM1 in the peripheral site significantly correlated with an increase in the infiltration of T cells. Furthermore, the expression of p62/SQSTM1 and Beclin‐1 correlated with that of HLA class I and class II in tumor cells, respectively. In addition, several unfavorable clinicopathological parameters correlated with an increase in the expression of LC3 in the peripheral site. The correlation observed between LC3 or p62/SQSTM1 and the infiltration of T cells suggests that autophagy may actively mobilize immune cells toward the cancer bed. Meanwhile, the three autophagy‐associated proteins examined were linked to malignant potential and an unfavorable prognosis.

Novel Method for Recording Vestibular Evoked Myogenic Potential: Minimally Invasive Recording on Neck Extensor Muscles†

Objectives: Vestibular evoked myogenic potential (VEMP) has been used to test vestibulocollic reflex. However, VEMP is not stable on elderly patients because of their weak muscular strength. In this study, we tried to record VEMP on median neck extensor muscles with weak muscular contraction

Cancer-associated fibroblasts promote an immunosuppressive microenvironment through the induction and accumulation of protumoral macrophages

Stromal cells in the tumor microenvironment (TME) closely interact with tumor cells and affect tumor cell behavior in diverse manners. We herein investigated the mechanisms by which cancer-associated fibroblasts (CAFs) affect the functional polarization of tumor-associated macrophages (TAMs) in oral squamous cell carcinoma (OSCC) in vitro and in human cancer samples. The expression of CD68, CD14, CD163, CD200R, CD206, HLA-G, CD80, and CD86 was higher in CD14-positive cells co-cultured with the culture supernatants of CAFs established from OSCC specimens (CAF-educated cells) than in control cells. The gene expression level of ARG1, IL10, and TGFB1 was increased in CAF-educated cells. CAF-educated cells suppressed T cell proliferation more strongly than control cells, and the neutralization of TGF-β IL-10, or arginase I significantly restored T cell proliferation. We then investigated the relationship between the infiltration of CAFs and TAMs using tissue samples obtained from patients with OSCC. The infiltration of CAFs was associated with the numbers of CD68-positive and CD163-positive macrophages. It also correlated with lymphatic invasion, vascular invasion, lymph node involvement, and the TNM stage. The infiltration of CAFs was identified as an independent prognostic factor in OSCC. Our results indicate that CAFs play important roles in shaping the tumor immunosuppressive microenvironment in OSCC by inducing the protumoral phenotype of TAMs. Therapeutic strategies to reverse CAF-mediated immunosuppression need to be considered.