Jun-ichi Kobayashi

Comparative study on the immunogenicity between an HLA-A24-restricted cytotoxic T-cell epitope derived from survivin and that from its splice variant survivin-2B in oral cancer patients.

BackgroundWe previously reported an HLA-A24-restricted cytotoxic T-cell epitope, Survivin-2B80-88, derived from a splice variant of survivin, survivin-2B. In this report, we show a novel HLA-A24-restricted T-cell epitope, Survivin-C58, derived from a wild type survivin, and compared their immunogenicity in oral cancer patients.MethodsBy stimulating peripheral blood lymphocytes of HLA-A24-positive cancer patients with Survivin-C58 peptide in vitro, the peptide-specific CTLs were induced. In order to compare the immunogenic potential between C58 peptide and 2B80-88 peptide, peripheral blood T-cells from thirteen HLA-A24-positive oral cancer patients were stimulated with either or both of these two peptides.ResultsSurvivin-2B80-88 peptide-specific CTLs were induced from four patients, and C58 peptide-specific CTLs were induced from three out of eight patients with over stage II progression. The CTLs exerted cytotoxicity against HLA-A24-positive tumor cells. In contrast, CTL induction failed from a healthy volunteer and all four patients with cancer stage I.ConclusionIt was indicated that a splicing variant-derived peptide and wild type survivin-derived peptide might have a comparable potency of CTL induction, and survivin targeting immunotherapy using survivin-2B80-88 and C58 peptide cocktail should be suitable for HLA-A24+ oral cancer patients.

Phase I clinical trial of survivin‐derived peptide vaccine therapy for patients with advanced or recurrent oral cancer

Survivin, a member of the inhibitor of apoptosis protein (IAP) family, is abundantly expressed in most malignancies, but is hardly detectable in normal adult tissues. Previously we have identified a human leukocyte antigen (HLA)‐A24‐restricted antigenic peptide, survivin‐2B80‐88 (AYACNTSTL), recognized by CD8+ cytotoxic T lymphocytes (CTL). Survivin‐2B80‐88‐specific CTL were induced efficiently from peripheral blood mononuclear cells (PBMC) of oral cancer patients after stimulation with the peptide in vitro. We conducted a phase I clinical study to evaluate the safety and the efficacy of survivin‐2B80‐88 peptide vaccination in HLA‐A24‐positive patients with advanced or recurrent oral cancer. The vaccines were given subcutaneously or intratumorally six times at 14‐day intervals. Eleven patients were enrolled and 10 patients completed the vaccination protocol. No adverse events were observed in any patients. In two patients, the levels of serum squamous cell carcinoma (SCC) antigen decreased transiently during the period of vaccination. Tumor regression that was compatible with a partial response (PR) was noted in one patient. The remaining nine patients experienced progressive disease (PD). Immunologically, an increase of the peptide‐specific CTL frequency was detected in six of the eight patients evaluated by HLA‐A24/peptide tetramer analysis. The present clinical trial revealed that survivin‐2B peptide vaccination was safe and had therapeutic potential for oral cancer patients. However, subsequent clinical trials in combination with various adjuvant drugs will be required to improve the immunological and therapeutic efficacy. This trial was registered with University Hospital Medical Information Network (UMIN) number UMIN000000976. (Cancer Sci 2011; 102: 324–329)

High expression of ALDH1 and SOX2 diffuse staining pattern of oral squamous cell carcinomas correlates to lymph node metastasis.

One of the major factors involved in the prognosis of oral squamous cell carcinoma (OSCC) patients is metastasis. Recent progress in cancer stem‐like cell/cancer‐initiating cell (CSC/CIC) research indicates that CSCs are related to metastasis. Aldehyde dehydrogenase 1 – (ALDH1) and SRY‐related HMG‐box gene 2 (SOX2) have recently been shown to be putative CSC markers for several human malignancies. The aim of this study was to determine the association of ALDH1 and SOX2 expression in oral squamous cell carcinoma (OSCC) with lymph node metastasis. Immunohistochemical staining of ALDH1, SOX2 and Ki67 was performed in 80 OSCC tissues. High expression rates of ALDH1 (2%–40%) were found to be related to lymph node metastasis (P = 0.0017). Interestingly, we found that SOX2 staining could be classified into two patterns: (i) peripheral staining pattern; and (ii) diffuse staining pattern. The diffuse staining pattern showed a significant correlation with lymph node metastasis (P < 0.001). No correlation was found between Ki67 staining and lymph node metastasis (P = 0.4724). The ALDH1 positive staining rates in metastatic lymph nodes were higher than that in corresponding primary OSCC tissues. These results indicate that high expression rates of ALDH1 and SOX2 diffuse staining patterns might be novel prediction markers for OSCC lymph node metastasis.

Small proline-rich protein-1B is overexpressed in human oral squamous cell cancer stem-like cells and is related to their growth through activation of MAP kinase signal.

Cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are considered to be essential for tumor maintenance, recurrence and metastasis. Therefore, eradication of CSCs/CICs is essential to cure cancers. However, the molecular mechanisms of CSCs/CICs are still elusive. In this study, we investigated the molecular mechanism of the cell growth of oral CSCs/CICs. Oral CSCs/CICs were isolated as aldehyde dehydrogenase 1 bright (ALDH1(br)) cells by the ALDEFLUOR assay. Small proline-rich protein-1B (SPRR1B) gene was shown to be overexpressed in ALDH1(br) cells by a cDNA microarray and RT-PCR. SPRR1B was shown to have a role in cell growth and maintenance of ALDH1(br) cells by SPRR1B overexpression and knockdown experiments. To elucidate the molecular mechanism by which SPRR1B regulates cell growth, further cDNA microarray analysis was performed using SPRR1B-overexpressed cells and cells with SPRR1B knocked down by siRNA. Expression of the tumor suppressor gene Ras association domain family member 4 (RASSF4) was found to be suppressed in SPRR1B-overexpressed cells. On the other hand, the expression of RASSF4 was enhanced in cells in which SPRR1B expression was knocked down by SPRR1B-specific siRNA. RASSF4 has an RA (Ras association) domain, and we thus hypothesized that RASSF4 modulates the MAP kinase signal downstream of the Ras signal. MAP kinase signal was activated in SPRR1B-overexpressed cells, whereas the signal was suppressed in SPRR1B knocked down cells. Taken together, the results indicate that the expression of SPRR1B is upregulated in oral CSCs/CICs and that SPRR1B has a role in cell growth by suppression of RASSF4.

Hypoxia-induced epithelial-mesenchymal transition is regulated by phosphorylation of GSK3-β via PI3 K/Akt signaling in oral squamous cell carcinoma

OBJECTIVE Epithelial-mesenchymal transition (EMT) plays an important role in cancer invasion and metastasis induced by hypoxia. Here, we examined whether phosphorylation of GSK3-β via phosphoinositide 3-kinase (PI3 K)/Akt signaling is involved in enhancing the hypoxia-induced EMT in oral squamous cell carcinoma (OSCC). STUDY DESIGN Experiments were performed in OSCC cell lines (HSC-2, HSC-3, HSC-4, SAS, and HO-1-U-1) under normoxic or hypoxic conditions. The EMT was assessed by Matrigel invasion assays and wound healing assays. OSCC cell lines (HSC-2 and HSC-4) overexpressing hypoxia-inducible factor (HIF)-1α were established to examine the effects of HIF-1α on EMT-related factors. Immunohistochemical staining was performed to examine phosphorylation of GSK3-β in 33 cases of tongue squamous cell carcinoma. RESULTS Under hypoxic conditions, OSCC cell lines exhibited HIF-1α expression and showed evidence of the EMT. In cells overexpressing HIF-1α, the levels of phospho-Akt and phospho-GSK3-β were increased, resulting in induction of the EMT. Inhibition of GSK3-β phosphorylation suppressed these effects. Moreover, the intensity of pGSK3-β staining was significantly increased with cN stage and cTNM stage in patients with tongue squamous cell carcinoma. CONCLUSIONS Our data showed that the hypoxia-induced EMT in OSCC was enhanced by GSK3-β phosphorylation, suggesting that GSK3-β may be important in the invasion and metastasis of OSCC.

Six-transmembrane epithelial antigen of the prostate-1 plays a role for in vivo tumor growth via intercellular communication

Six-transmembrane epithelial antigen of the prostate-1 (STEAP-1) is a novel cell surface protein overexpressed only in the prostate among normal tissues and various types of cancer including prostate, bladder, lung, and ovarian cancer. Although its function in prostate and tumor cells has been remained unclear, due to its unique and restricted expression, STEAP-1 is expected to be an attractive target for cancer therapy. Here, we show that knockdown of STEAP-1 in human cancer cells caused the retardation of tumor growth compared with wild type in vivo. In contrast, STEAP-1 introduced tumor cells augmented the tumor growth compared with STEAP-1-negative wild type cells. Using dye transfer assay, we demonstrate that the STEAP-1 is involved in intercellular communication between tumor cells and adjacent tumor stromal cells and therefore may play a key role for the tumor growth in vivo. These data indicate the inhibition of the STEAP-1 function or expression can be a new strategy for cancer therapy.

Granulocyte colony-stimulating factor-producing squamous cell carcinoma of the lower gingiva: a case report

The present study summarizes our experience in treating a patient with a suspected granulocyte colony-stimulating factor (G-CSF)-producing squamous cell carcinoma (SCC) of the lower gingiva, which is a rather rare entity.A 56-year-old woman underwent surgical excision of palate leukoplakia in 1996. In 2009, however, a leukoplakic superficial tumor was detected in the lower left gingiva, for which the patient underwent gingivectomy. This was subsequently diagnosed as SCC. The patient also underwent superselective arterial injection chemotherapy combined with radiotherapy, after local recurrence was observed. The patient was subsequently found to have bone metastasis. After chemotherapy combined with radiotherapy, the patient underwent segmental resection of the lower left jaw, left supraomohyoid neck dissection, and lower jaw reconstruction using titanium plates. Resection of the left femoral tumor and left total knee replacement were also performed. Computed tomography scan performed 1 month after the surgeries revealed multiple lung, liver, spine, and subcutaneous metastases. The patient also exhibited a sudden increase in her white blood cell (WBC) count and a fever that could not be alleviated, despite treatment with antibacterial drugs. A G-CSF-producing tumor was therefore suspected. Serum G-CSF level was high at 250 pg/ml.The patients WBC count increased to 32 × 103/ml and her general condition suddenly deteriorated, and she died as a result of multiple organ failure. A final diagnosis of G-CSF-producing SCC of the lower gingiva was made based on the patients clinical course.

Clonal diversity of cytotoxic T lymphocytes that recognize autologous oral squamous cell carcinoma

Cytotoxic T lymphocytes (CTLs) play an essential role in immunologic responses for tumor rejection. In the past decade, various melanoma tumor-associated antigens (TAAs) have been identified, and several clinical trials of vaccination immunotherapy and adoptive immunotherapy using such antigens with or without adjuvants have had fascinating results. However, this has not been the case with oral squamous cell carcinoma (OSCC) because of the difficulty of establishing oral cancer cell lines and CTLs against autologous oral cancer cells. Therefore, few oral cancer antigens have been identified with such CTLs. We herein present the successful establishment of an oral squamous cell carcinoma cell line, POT-1, and an HLA-A24-restricted CTL line (TcPOT-1) from a patients autologous peripheral blood lymphocytes. TcPOT-1 recognized autologous POT-1 cells in an HLA-A24-restricted manner, and also allogeneic HLA-A24 (+) OSCC cell lines OSC-70 and HSC-2. We also succeeded in isolating two distinct CTL clones from TcPOT-1, HLA-A24-restricted CTL clone 4F11 and HLA-A33-restricted clone 4A11. Both of these clones recognized autologous POT-1 but not allogeneic OSSC cell lines. These data imply that the TcPOT-1 CTL line may include several CTL subpopulations with distinct antigen specificities, such as an HLA-A24-restricted POT-1-specific clone, HLA-A33-restricted POT-1-specific clone, and HLA-A24-restricted allogeneic OSCC-recognizing clone. Therefore, precise analysis of TcPOT-1-recognizing antigens may provide us with important information on as-yet-unknown tumor rejection antigens in OSCC.

Tumor budding is an independent prognostic marker in early stage oral squamous cell carcinoma: With special reference to the mode of invasion and worst pattern of invasion

Pathologically proven regional lymph node metastasis affects the prognosis in early stage oral cancer. Therefore we investigated invasive tumor patterns predicting nodal involvement and survival in patients with clinically node-negative T1 and T2 oral squamous cell carcinoma (cT1,2N0M0 OSCC). Ninety-one cases of cT1,2N0M0 OSCC treated with transoral resection of the primary tumor were assessed based on 3 types of invasive tumor patterns on histopathologic and pancytokeratin-stained immunohistological sections: the mode of invasion, worst pattern of invasion (WPOI), and tumor budding. The correlations among invasive tumor patterns, regional metastasis, and disease-free survival were analyzed. Of the 91 cases, 22 (24%) had pathologically proven regional metastasis. The mode of invasion (p<0.01) and tumor budding (p<0.01) were associated with regional metastasis as well as lymphovascular invasion (p = 0.04) in univariate analysis. In logistic regression analysis, however, tumor budding was the only independent predictor of regional metastasis (hazard ratio (HR) = 3.05, 95% confidence interval (CI) = 0.29–5.30, p<0.01). All three invasive patterns, the mode of invasion, WPOI, and tumor budding, were found to be significant predictors of 5-year disease-free survival (p<0.01, p = 0.03, and p<0.01, respectively) as well as lymphovascular invasion (p = 0.02) and perineural invasion (p = 0.02). A final model for Cox multivariate analysis identified the prognostic advantage of the intensity of tumor budding (HR = 2.19, 95% CI = 1.51–3.18, p<0.01) compared with the mode of invasion and WPOI in disease-free survival. Our results indicate that the intensity of tumor budding may be a novel diagnostic biomarker, as well as a therapeutic tool, for regional metastasis in patients with cT1,2N0M0 OSCC. If the pancytokeratin-based immunohistochemical features of more than five buds, and a grade 4C or 4D mode of invasion are identified, careful wait-and-see follow-up in a short period with the use of imaging modalities is desirable. If there are more than ten buds, a grade 4D mode of invasion, or WPOI-5 in the same section, wide resection of the primary tumor with elective neck dissection should be recommended.

Screening for long noncoding RNAs associated with oral squamous cell carcinoma reveals the potentially oncogenic actions of DLEU1

Recent studies have shown that long noncoding RNAs (lncRNAs) have pivotal roles in human malignancies, although their significance in oral squamous cell carcinoma (OSCC) is not fully understood. In the present study, we identified lncRNAs functionally associated with OSCC. By analyzing RNA-seq datasets obtained from primary head and neck squamous cell carcinoma (HNSCC), we identified 15 lncRNAs aberrantly expressed in cancer tissues. We then validated their expression in 18 OSCC cell lines using qRT-PCR and identified 6 lncRNAs frequently overexpressed in OSCC. Among those, we found that knocking down DLEU1 (deleted in lymphocytic leukemia 1) strongly suppressed OSCC cell proliferation. DLEU1 knockdown also suppressed migration, invasion, and xenograft formation by OSCC cells, which is suggestive of its oncogenic functionality. Microarray analysis revealed that DLEU1 knockdown significantly affects expression of a number of cancer-related genes in OSCC cells, including HAS3, CD44, and TP63, suggesting that DLEU1 regulates HA-CD44 signaling. Expression of DLEU1 was elevated in 71% of primary OSCC tissues, and high DLEU1 expression was associated with shorter overall survival of HNSCC patients. These data suggest that elevated DLEU1 expression contributes to OSCC development, and that DLEU1 may be a useful therapeutic target in OSCC.