Suguru Hayase

Thyroid Regeneration: Characterization of Clear Cells After Partial Thyroidectomy

Although having the capacity to grow in response to a stimulus that perturbs the pituitary-thyroid axis, the thyroid gland is considered not a regenerative organ. In this study, partial thyroidectomy (PTx) was used to produce a condition for thyroid regeneration. In the intact thyroid gland, the central areas of both lobes served as the proliferative centers where microfollicles, and bromodeoxyuridine (BrdU)-positive and/or C cells, were localized. Two weeks after PTx, the number of BrdU-positive cells and cells with clear or faintly eosinophilic cytoplasm were markedly increased in the central area and continuous to the cut edge. Clear cells were scant in the cytoplasm, as determined by electron microscopy; some retained the characteristics of calcitonin-producing C cells by having neuroendocrine granules, whereas others retained follicular cell-specific features, such as the juxtaposition to a lumen with microvilli. Some cells were BrdU-positive and expressed Foxa2, the definitive endoderm lineage marker. Serum TSH levels drastically changed due to the thyroidectomy-induced acute reduction in T(4)-generating tissue, resulting in a goitrogenesis setting. Microarray followed by pathway analysis revealed that the expression of genes involved in embryonic development and cancer was affected by PTx. The results suggest that both C cells and follicular cells may be altered by PTx to become immature cells or immature cells that might be derived from stem/progenitor cells on their way to differentiation into C cells or follicular cells. These immature clear cells may participate in the repair and/or regeneration of the thyroid gland.

Stem Cell Antigen 1-Positive Mesenchymal Cells Are the Origin of Follicular Cells during Thyroid Regeneration

Many tissues are thought to contain adult stem/progenitor cells that are responsible for repair of the tissue where they reside upon damage and/or carcinogenesis, conditions when cellular homeostasis becomes uncontrolled. While the presence of stem/progenitor cells of the thyroid has been suggested, how these cells contribute to thyroid regeneration remains unclear. Here we show the origin of thyroid follicular cells and the process of their maturation to become follicular cells during regeneration. By using β-galactosidase (β-gal) reporter mice in conjunction with partial thyroidectomy as a model for thyroid regeneration, and bromodeoxyuridine (BrdU) long label-retaining cell analysis, we demonstrated that stem cell antigen 1 (Sca1) and BrdU-positive, but β-gal and NKX2-1 negative cells were found in the non-follicular mesenchymal area 7 days after partial thyroidectomy. They temporarily co-expressed cytokeratin 14, and were observed in part of follicles by day 35 post-partial thyroidectomy. Sca1, BrdU, β-gal, and NKX2-1-positive cells were found 120 days post-partial thyroidectomy. These results suggested that Sca1 and BrdU positive cells may participate in the formation of new thyroid follicles after partial thyroidectomy. The process of thyroid follicular cell regeneration was recapitulated in ex vivo thyroid slice collagen gel culture studies. These studies will facilitate research on thyroid stem/progenitor cells and their roles in thyroid diseases, particularly thyroid carcinomas.

Ectopic expression of MECA‐79 as a novel prognostic indicator in gastric cancer

The aim of this study was to clarify the clinical implications of a unique carbohydrate determinant, MECA‐79, in gastric cancer specimens and cells. Immunohistochemical analysis showed that 62 of 225 (27.6%) cases were defined as positive for MECA‐79. MECA‐79 expression was correlated with depth of invasion, venous invasion, TNM stage, and distant metastasis. In survival analyses, patients with MECA‐79 expression had worse prognosis by the log–rank test. Multivariate analysis of the Cox proportional hazard model showed that MECA‐79 expression was an independent factor of a worse cancer‐specific survival. Among 11 gastric cancer cells, MECA‐79 was observed in only MKN7 cells, which also expressed GlcNAc6ST‐2 transcript. A knockdown of GlcNAc6ST‐2 in MKN7 cells showed a markedly reduced expression of MECA‐79, suggesting that GlcNAc‐sulfation of MECA‐79 is mainly synthesized by GlcNAc6ST‐2. Furthermore, real‐time RT‐PCR analysis revealed that GlcNAc6ST‐2 was significantly increased in cancer tissues compared with paired normal mucosa. In conclusion, the expression of MECA‐79 could be a useful marker for the prognosis of gastric cancer. Our results might also provide novel perspectives on the biology of MECA‐79 and GlcNAc6ST‐2 in cancer progression and metastasis. (Cancer Sci 2011; 102: 1088–1094)

Stromal VCAN expression as a potential prognostic biomarker for disease recurrence in stage II-III colon cancer.

To develop prognostic biomarkers that can discriminate stage II-III colorectal cancer patients with high risk of postoperative recurrence, we conducted a genome-wide screening of relapse-related genes utilizing multiple microarray cohorts. Among differentially expressed genes between tumor and nontumor, we identified eight candidate genes associated with relapse in two datasets of stage II-III patients (n = 94 and 145, respectively, P < 0.05). Using datasets of laser-microdissected samples and FACS-purified cell populations, the localization of candidate genes, including COL4A2, COL4A1, VCAN and SERPINE1, were found predominantly in cancer stroma rather than epithelial components. Among those relapse-related stromal genes, VCAN mRNA, specifically expressed in cancer-associated fibroblasts, was further validated to be a prognostic factor in two additional independent datasets, consisting of 453 (P = 0.0334) and 89 (P = 0.0041) stage II-III patients. Furthermore, in our large set of formalin-fixed paraffin-embedded cohort (n = 338), VCAN protein was detected exclusively in cancer stroma by immunohistochemistry, demonstrating a stepwise increase of stromal VCAN from normal tissues through stage 0 to stage IV tumors. Stromal VCAN protein was associated with shorter relapse-free survival (RFS) in stage II-III colon cancer, independent of other clinical factors by multivariate analysis (P = 0.004). Stratified analyses revealed that stromal VCAN was a strong prognostic indicator particularly in stage II colon cancer (P = 0.0029). In all five analyzed cohorts, the expression of VCAN, in transcript or protein levels, was associated with poor RFS in stage II-III patients. We conclude that VCAN is a promising biomarker to identify stage II-III patients at high risk of relapse who may benefit from intensive postoperative management.

Expression of Stanniocalcin 1 in Thyroid Side Population Cells and Thyroid Cancer Cells

BACKGROUND Mouse thyroid side population (SP) cells consist of a minor population of mouse thyroid cells that may have multipotent thyroid stem cell characteristics. However the nature of thyroid SP cells remains elusive, particularly in relation to thyroid cancer. Stanniocalcin (STC) 1 and 2 are secreted glycoproteins known to regulate serum calcium and phosphate homeostasis. In recent years, the relationship of STC1/2 expression to cancer has been described in various tissues. METHOD Microarray analysis was carried out to determine genes up- and down-regulated in thyroid SP cells as compared with non-SP cells. Among genes up-regulated, stanniocalcin 1 (STC1) was chosen for study because of its expression in various thyroid cells by Western blotting and immunohistochemistry. RESULTS Gene expression analysis revealed that genes known to be highly expressed in cancer cells and/or involved in cancer invasion/metastasis were markedly up-regulated in SP cells from both intact as well as partial thyroidectomized thyroids. Among these genes, expression of STC1 was found in five human thyroid carcinoma-derived cell lines as revealed by analysis of mRNA and protein, and its expression was inversely correlated with the differentiation status of the cells. Immunohistochemical analysis demonstrated higher expression of STC1 in the thyroid tumor cell line and thyroid tumor tissues from humans and mice. CONCLUSION These results suggest that SP cells contain a population of cells that express genes also highly expressed in cancer cells including Stc1, which warrants further study on the role of SP cells and/or STC1 expression in thyroid cancer.

An Adult Mouse Thyroid Side Population Cell Line that Exhibits Enriched Epithelial–Mesenchymal Transition

BACKGROUND Studies of thyroid stem/progenitor cells have been hampered due to the small organ size and lack of tissue, which limits the yield of these cells. A continuous source that allows the study and characterization of thyroid stem/progenitor cells is desired to push the field forward. METHOD A cell line was established from Hoechst-resistant side population cells derived from mouse thyroid that were previously shown to contain stem/progenitor-like cells. Characterization of these cells were carried out by using in vitro two- and three-dimensional cultures and in vivo reconstitution of mice after orthotopic or intravenous injection, in conjunction with quantitative reverse transcription polymerase chain reaction, Western blotting, immunohisto(cyto)chemistry/immunofluorescence, and RNA seq analysis. RESULTS These cells were named SPTL (side population cell-derived thyroid cell line). Under low serum culturing conditions, SPTL cells expressed the thyroid differentiation marker NKX2-1, a transcription factor critical for thyroid differentiation and function, while no expression of other thyroid differentiation marker genes were observed. SPTL cells formed follicle-like structures in Matrigel® cultures, which did not express thyroid differentiation marker genes. In mouse models of orthotopic and intravenous injection, the latter following partial thyroidectomy, a few SPTL cells were found in part of the follicles, most of which expressed NKX2-1. SPTL cells highly express genes involved in epithelial-mesenchymal transition, as demonstrated by RNA seq analysis, and exhibit a gene-expression pattern similar to anaplastic thyroid carcinoma. CONCLUSION These results demonstrate that SPTL cells have the capacity to differentiate into thyroid to a limited degree. SPTL cells may provide an excellent tool to study stem cells, including cancer stem cells of the thyroid.

Enhanced expression of KIF4A in colorectal cancer is associated with lymph node metastasis

Kinesin family member 4A (KIF4A) is a member of the kinesin 4 subfamily of kinesin-related proteins and serves an important role in cell division. The expression levels of KIF4A have been investigated in numerous types of cancer, including cervical, lung, oral, and breast cancer, and are established to be associated with poor patient prognosis. However, the role of KIF4A, as well as its expression in colorectal cancer (CRC), remains to be elucidated. Therefore, the current study investigated KIF4A expression levels in patients with CRC and demonstrated that its levels were increased in tumor tissues compared with non-tumor tissues. To investigate the functional role of KIF4A, KIF4A was knocked down in CRC cells and cell viability was evaluated. CRC cells with KIF4A knockdown exhibited lower cell proliferation compared with control cells. In addition, KIF4A expression levels, as determined by immunohistochemistry, were compared with the expression of Ki-67, but no significant associations were observed in the patients with CRC. Therefore, KIF4A was found to be upregulated in patients with CRC and downregulation of KIF4A reduced cell proliferation in CRC cells. These results suggest that KIF4A may be a potential therapeutic target, which may improve the outcomes of patients with CRC.

Upregulated solute carrier family 37 member 1 in colorectal cancer is associated with poor patient outcome and metastasis

Solute carrier (SLC) drug transporters exchange various molecules without energy from adenosine triphosphate hydrolysis, indicating an association with anticancer drug resistance. However, the expression and role of SLC transporters in malignant tumors has not yet been fully elucidated. Therefore, in the current study, the expression of SLC37A family genes was evaluated in patients with colorectal cancer (CRC), and it was revealed that SLC family 37 member 1 (SLC37A1) expression was significantly increased in tumorous tissues compared with that in non-tumorous tissues. The cases with upregulated expression of SLC37A1 by immunohistochemical staining were significantly associated with positive venous invasion and liver metastasis. Furthermore, upregulated SLC37A1 expression was associated with poor overall survival time in the present cohort. These results indicated that SLC37A1 is involved in the hematogenous metastasis of CRC. To investigate whether SLC37A1 is associated with hematogenous metastasis and glycolipid metabolism, SLC37A1 was knocked down in colon cancer cells, and the expression of sialyl Lewis A and sialyl Lewis X was observed to be decreased. In summary, upregulation of SLC37A1 was observed in patients with CRC, and was associated with poor patient outcomes and survival. To the best of our knowledge, the present study is the first to propose a key role of SLC37A1 in CRC, and additional studies are warranted to reveal the functional role of SLC37A1 in CRC development.

Immunotherapy for esophageal squamous cell carcinoma: a review

Cancer vaccines and immune checkpoint inhibitors (ICI) have recently been employed as immunotherapies for esophageal squamous cell carcinoma (ESCC). Cancer vaccines for ESCC have yielded several promising results from investigator-initiated phase I and II clinical trials. Furthermore, a Randomized Controlled Trial as an adjuvant setting after curative surgery is in progress in Japan. On the other hand, ICI, anti-CTLA-4 mAb and anti-PD-1 mAb, have demonstrated tumor shrinkage and improved overall survival in patients with multiple cancer types. For ESCC, several clinical trials using anti-PD-1/anti-PD-L1 mAb are underway with several recent promising results. In this review, cancer vaccines and ICI are discussed as novel therapeutic strategies for ESCC.

Prognostic impact of preoperative lymphocyte-to-monocyte ratio in patients with colorectal cancer with special reference to myeloid-derived suppressor cells

AIMS We aimed to investigate the relationship of colorectal cancer prognosis and inflammatory parameters, including neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-to-monocyte ratio (LMR), with reference to circulating myeloid-derived suppressor cells (MDSCs) in the current study. PATIENTS AND METHODS Thirty-five patients who underwent curative-intent surgery were enrolled.　A receiver-operating characteristic curve (ROC) was used to assess the usefulness of candidates for prognostic factors. Recurrence-free survival (RFS) was calculated using the Kaplan-Meier method, and the candidates for prognostic factors were assessed by a Cox proportional hazard model. RESULTS ROC curve analyses determined cutoff values for NLR and LMR as 2.9 and 2.4, respectively. The percentage of MDSCs in patients with LMR ≤ 2.4 was statistically higher than in those with LMR > 2.4 (p = 0.012). The patients with LMR ≤ 2.4 exhibited a statistically lower RFS than those with LMR > 2.4 (p = 0.008). These results were also observed in patients with stage II + III disease. LMR was an independent prognostic factor of RFS in colorectal cancer patients (hazard ratio: 7.757, 95% confidence interval: 1.462-41.152, p = 0.016). CONCLUSION Lower LMR was associated with poor prognosis in colorectal cancer patients; whereas, higher circulating MDSCs were observed in patients with lower LMR.