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Osteosarcoma (OS) is a highly malignant bone tumor and the prognosis for non‐responders to chemotherapy remains poor. Previous studies have shown that human sarcomas contain sarcoma‐initiating cells (SIC), which have the characteristics of high tumorigenesis and resistance to chemotherapy. In the present study, we characterized SIC of a novel OS cell line, screened for SIC‐related genes, and tried to regulate the proliferation of OS by metabolic interference. Initially, we established a new human OS cell line (OS13) and isolated clones showing higher tumorigenesis as SIC (OSHIGH) and counterpart clones. OSHIGH cells showed chemoresistance and their metabolism highly depended on aerobic glycolysis and suppressed oxidative phosphorylation. Using RNA‐sequencing, we identified LIN28B as a SIC‐related gene highly expressed in OSHIGH cells. mRNA of LIN28B was expressed in sarcoma cell lines including OS13, but its expression was not detectable in normal organs other than the testis and placenta. LIN28B protein was also detected in various sarcoma tissues. Knockdown of LIN28B in OS13 cells reduced tumorigenesis, decreased chemoresistance, and reversed oxidative phosphorylation function. Combination therapy consisting of a glycolysis inhibitor and low‐dose chemotherapy had antitumor effects. In conclusion, manipulation of glycolysis combined with chemotherapy might be a good adjuvant treatment for OS. Development of immunotherapy targeting LIN28B, a so‐called cancer/testis antigen, might be a good approach. Osteosarcoma‐initiating cell antigen LIN28B was expressed in sarcoma tissues. ES, epithelioid sarcoma; MFS, myxofibrosarcoma; OS, osteosarcoma; SS, synovial sarcoma.

Photodynamic diagnosis/therapy (PDD/PDT) are novel modalities for the diagnosis and treatment of cancer. The photosensitizer protoporphyrin IX is metabolized from 5-aminolevulinic acid (5-ALA) intracellularly, and PDD/PDT using 5-ALA have been approved in dermatologic malignancies and gliomas. However, the molecular mechanism that defines the efficacy of PDD/PDT is unknown. In this study, we analyzed the functions of ATP-binding cassette (ABC) transporters in PDD using 5-ALA. Most of the human gastrointestinal cancer line cells examined showed a homogenous staining pattern with 5-ALA, except for the pancreatic cancer line PANC-1, which showed heterogeneous staining. To analyze this heterogeneous staining pattern, single cell clones were established from PANC-1 cells and the expression of ABC transporters was assessed. Among the ABC transporter genes examined, ABCG2 showed an inverse correlation with the rate of 5-ALA-positive staining. PANC-1 clone #2 cells showed the highest level of ABCG2 expression and the lowest level of 5-ALA staining, with only a 0.6% positive rate. Knockdown of the ABCG2 gene by small interfering RNAs increased the positive rate of 5-ALA staining in PANC-1 wild-type and clone cells. Interestingly, PANC-1 clone #2 cells showed the high sphere-forming ability and tumor-formation ability, indicating that the cells contained high numbers of cancer stem cells (CSCs). Knockdown or inhibition of ABCG2 increased the rate of 5-ALA staining, but did not decrease sphere-forming ability. These results indicate that gastrointestinal cancer cell lines expressing high levels of ABCG2 are enriched with CSCs and show low rates of 5-ALA staining, but 5-ALA staining rates can be improved by inhibition of ABCG2.

Pathological histology examination involves handling a variety of specimens that are cut according to regulations and placed in cassettes. Tissue fragments in the cassettes are then diagnosed after processing, embedding, thin sectioning, staining and other procedures using a processing machine. Maintaining tissue fragment order and orientation during these processes is important for accurate diagnosis. In this study, we present a method of maintaining tissue fragment order and orientation using a thin film of ultra-high-strength agar and evaluate its usefulness during tissue sectioning.Cassettes were prepared, each containing three pieces of porcine liver, and compared embedding time with and without agar thin films (ATFs). Embedding was performed by three medical laboratory scientists with different levels of experience.To enable one-step tissue sample embedding, ATFs were integrated with samples in the cassettes. This resulted in an average reduction of 6.22 s of embedding time per cassette compared with traditional embedding methods.Through the use of ATFs, tissue fragment order and orientation is maintained, and embedding process time shortened. Additionally, ATFs are easily prepared and stored in 10% neutral buffered formalin over extended periods, allowing for immediate use during sectioning. This method is ideal to implement in busy pathology laboratories.

The prognosis of advanced pancreatic adenocarcinoma is still extremely poor. This study sought to determine the efficacy of, and immunological response to, peptide vaccination therapy in patients with this disease. In this multicenter randomized phase II study, patients with advanced pancreatic adenocarcinoma after gemcitabine and/or tegafur/gimeracil/oteracil were randomly assigned to 3 groups that each received a 2‐step treatment course. In Step 1, the groups received treatments of: (i) survivin 2B peptide (SVN‐2B) plus interferon‐β (IFNβ); (ii) SVN‐2B only; or (iii) placebo until the patients show progression. In Step 2, all patients who consented to participate received 4 treatments with SVN‐2B plus IFNβ. The primary endpoint was progression‐free survival (PFS) after initiation of Step 1 treatment. Secondary endpoints included immunological effects assessed by analysis of PBMCs after Step 1. Eighty‐three patients were randomly assigned to receive SVN‐2B plus IFNβ (n = 30), SVN‐2B (n = 34), or placebo (n = 19). No significant improvement in PFS was observed. Survivin 2B‐specific CTLs were found to be increased in the SVN‐2B plus IFNβ group by tetramer assay. Among patients who participated in Step 2, those who had received SVN‐2B plus IFNβ in Step 1 showed better overall survival compared with those who had received placebo in Step 1. Patients vaccinated with SVN‐2B plus IFNβ did not have improved PFS, but showed significant immunological reaction after vaccination. Subgroup analysis suggested that a longer SVN‐2B plus IFNβ vaccination protocol might confer survival benefit. (Clinical trial registration number: UMIN 000012146). Randomized phase II trial of survivin 2B peptide vaccination for patients with HLA‐A24‐positive pancreatic adenocarcinoma is reported. Although peptide vaccination did not improved progression‐free survival, subgroup analysis revealed that longer peptide vaccination might confer survival benefit.

Glypican‐3 (GPC3) is an onco‐fetal antigen that is overexpressed in human hepatocellular carcinoma (HCC), and is only expressed in the placenta and embryonic liver among normal tissues. Previously, we identified an HLA‐A2‐restricted GPC3144–152 (FVGEFFTDV) peptide that can induce GPC3‐reactive CTLs without inducing autoimmunity in HLA‐A2 transgenic mice. In this study, we carried out a phase I clinical trial of HLA‐A2‐restricted GPC3144–152 peptide vaccine in 14 patients with advanced HCC. Immunological responses were analyzed by ex vivoγ‐interferon enzyme‐linked immunospot assay. The frequency of GPC3144–152 peptide‐specific CTLs after vaccination (mean, 96; range, 5–441) was significantly larger than that before vaccination (mean, 6.5; range, 0–43) (P < 0.01). An increase in the GPC3144–152 peptide‐specific CTL frequency was observed in 12 (86%) of 14 patients after vaccination. Additionally, there was a significant correlation between the maximum value of GPC3144–152 peptide‐specific CTLs after vaccination and the dose of the peptide injected (P = 0.0166, r = 0.665). Moreover, we established several GPC3144–152 peptide‐specific CTL clones from PBMCs of patients vaccinated with GPC3144–152 peptide by single cell sorting using Dextramer and CD107a antibody. These CTL clones had high avidity (the recognition efficiency showing 50% cytotoxicity was 10−10 or 10−11 M) and could recognize HCC cell lines expressing GPC3 in an HLA‐class I‐restricted manner. These results suggest that GPC3144–152 peptide vaccine can induce high avidity CTLs capable of killing HCC cells expressing GPC3. This trial was registered with University Hospital Medical Information Network number 000001395. (Cancer Sci 2011; 102: 918–925)

Eribulin inhibits microtubule polymerization and improves the overall survival of patients with recurrent metastatic breast cancer. A subgroup analysis revealed a low neutrophil to lymphocyte ratio (NLR) (<3) to be a prognostic factor of eribulin treatment. We thus hypothesized that eribulin might be related to the immune response for breast cancer cells and we analyzed the effects of eribulin on the immune system. Immunohistochemical staining revealed that human leukocyte antigen (HLA) class I expression was increased in clinical samples after eribulin treatment. In vitro assays revealed that eribulin treatment increased HLA class I expression in breast cancer line cells. RNA‐sequencing demonstrated that eribulin treatment increased the expression of the NOD‐like family CARD domain‐containing 5 (NLRC5), a master regulator of HLA class I expression. Eribulin treatment increased the NY‐ESO‐1‐specific T‐cell receptor (TCR) transduced T (TCR‐T) cell response for New York oesophageal squamous cell carcinoma 1 (NY‐ESO‐1) overexpressed breast cancer cells. The eribulin and TCR‐T combined therapy model revealed that eribulin and immunotherapy using TCR‐T cells has a synergistic effect. In summary, eribulin increases the expression of HLA class 1 via HLA class 1 transactivatior NLRC5 and eribulin combination with immunotherapy can be effective for the treatment of breast cancer. Eribulin inhibits microtubule polymerization and has been approved for recurrent metastatic breast cancer. Eribulin enhanced recognition by Cytotoxic T lymphocytes (CTLs) by increasing the expression of human leukocyte antigen (HLA) class 1 via the HLA class 1 transactivator neutrophil to lymphocyte ratio family CARD domain‐containing 5, thus eribulin can be used as an immunopotentiator.

We previously identified papillomavirus binding factor (PBF) as an osteosarcoma antigen recognized by an autologous cytotoxic T lymphocyte clone. Vaccination with PBF‐derived peptide presented by HLA‐A24 (PBF peptide) elicited strong immune responses. In the present study, we generated T cell receptor‐engineered T cells (TCR‐T cells) directed against the PBF peptide (PBF TCR‐T cells). PBF TCR was successfully transduced into T cells and detected using HLA‐A*24:02/PBF peptide tetramer. PBF TCR‐T cells generated from a healthy donor were highly expanded and recognized T2‐A24 cells pulsed with PBF peptide, HLA‐A24+ 293T cells transfected with PBF cDNA, and sarcoma cell lines. To establish an adoptive cell therapy model, we modified the PBF TCR by replacing both α and β constant regions with those of mice (hybrid PBF TCR). Hybrid PBF TCR‐T cells also showed reactivity against T2‐A24 cells pulsed with PBF peptide and to HLA‐A24+ 293T cells transfected with various lengths of PBF cDNA including the PBF peptide sequence. Subsequently, we generated target cell lines highly expressing PBF (MFH03‐PBF [short] epitope [+]) containing PBF peptide with in vivo tumorigenicity. Hybrid PBF TCR‐T cells exhibited antitumor effects compared with mock T cells in NSG mice xenografted with MFH03‐PBF (short) epitope (+) cells. CD45+ T cells significantly infiltrated xenografted tumors only in the hybrid PBF TCR T cell group and most of these cells were CD8‐positive. CD8+ T cells also showed Ki‐67 expression and surrounded the CD8‐negative tumor cells expressing Ki‐67. These findings suggest that PBF TCR‐T cell therapy might be a candidate immunotherapy for sarcoma highly expressing PBF. We developed TCR‐T cells targeting sarcoma‐associated antigen PBF (PBF TCR‐T cells). PBF TCR‐T cells showed anti‐tumor effects against sarcoma cell lines in vitro and in vivo. PBF TCR‐T cell therapy might be a candidate immunotherapy for sarcoma highly expressing PBF.

In a previous study, we found that DNAJB8, a heat shock protein (HSP) 40 family member is expressed in kidney cancer stem‐like cells (CSC)/cancer‐initiating cells (CIC) and that it has a role in the maintenance of kidney CSC/CIC. Heat shock factor (HSF) 1 is a key transcription factor for responses to stress including heat shock, and it induces HSP family expression through activation by phosphorylation. In the present study, we therefore examined whether heat shock (HS) induces CSC/CIC. We treated the human kidney cancer cell line ACHN with HS, and found that HS increased side population (SP) cells. Western blot analysis and qRT‐PCR showed that HS increased the expression of DNAJB8 and SOX2. Gene knockdown experiments using siRNAs showed that the increase in SOX2 expression and SP cell ratio depends on DNAJB8 and that the increase in DNAJB8 and SOX2 depend on HSF1. Furthermore, treatment with a mammalian target of rapamycin (mTOR) inhibitor, temsirolimus, decreased the expression of DNAJB8 and SOX2 and the ratio of SP cells. Taken together, the results indicate that heat shock induces DNAJB8 by activation of HSF1 and induces cancer stem‐like cells. Cancer stem cells are induced by cellular stress. Cellular stress activates HSF1 and induces DNAJB8, a cancer stem cell‐specific heat shock protein. HSF1/DNAJB8 is a novel pathway of cancer stem cells.

Peptide–major histocompatibility complex (pMHC) multimers enable the detection of antigen-specific T cells in studies ranging from vaccine efficacy to cancer immunotherapy. However, this technology is unreliable when applied to pMHC class II for the detection of CD4 + T cells. Here, using a combination of molecular biological and immunological techniques, we cloned sequences encoding human leukocyte antigen (HLA)-DP, HLA-DQ and HLA-DR molecules with enhanced CD4 binding affinity (with a K d of 8.9 ± 1.1 µM between CD4 and affinity-matured HLA-DP4) and produced affinity-matured class II dimers that stain antigen-specific T cells better than conventional multimers in both in vitro and ex vivo analyses. Using a comprehensive library of dimers for HLA-DP4, which is the most frequent HLA allele in many ancestry groups, we mapped 103 HLA-DP4-restricted epitopes derived from diverse tumor-associated antigens and cloned the cognate T-cell antigen receptor (TCR) genes from in vitro-stimulated CD4 + T cells. The availability of affinity-matured class II dimers across HLA-DP, HLA-DQ and HLA-DR alleles will aid in the investigation of human CD4 + T-cell responses. CD4 + T cells are readily detected with class II MHC dimers.

Recently, the SOX2 gene has been reported to be amplified in human lung squamous cell carcinomas. However, its roles in human lung adenocarcinomas are still elusive. In this study, we analyzed the functions of SOX2 in cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) derived from human lung adenocarcinoma. Human lung CSCs/CICs were isolated as higher tumorigenic side population (SP) cells using Hoechst 33342 dye from several lung cancer cell lines. Four of nine lung cancer cell lines were positive for SP cells (LHK2, 1-87, A549, Lc817). The ratios of SP cells ranged from 0.4% for Lc817 to 2.8% for LHK2. To analyze the molecular aspects of SP cells, we performed microarray screening and RT-PCR analysis, and isolated SOX2 as one of a SP cell-specific gene. SOX2 was expressed predominantly in LHK2 and 1-87 SP cells, and was also expressed in several other cancer cell lines. The expression of SOX2 protein in primary human lung cancer tissues were also confirmed by immunohistochemical staining, and SOX2 was detected in more than 80% of primary lung cancer tissues. To address SOX2 molecular functions, we established a SOX2-overexpressed LHK2 and A549 cell line (LHK2-SOX2 and A549-SOX2). LHK2-SOX2 cells showed higher rates of SP cells and higher expression of POU5F1 compared with control cells. LHK2-SOX2 and A549-SOX2 cells showed relatively higher tumorigenicity than control cells. On the other hand, SOX2 mRNA knockdown of LHK2 SP cells by gene-specific siRNA completely abrogated tumorigenicity in vivo. These observations indicate that SOX2 has a role in maintenance of stemness and tumorigenicity of human lung adenocarcinoma CSCs/CICs and is a potential target for treatment.