Yoshihiro Komai

Identification of stem cells that maintain and regenerate lingual keratinized epithelial cells

Lingual keratinized epithelial cells, which constitute the filiform papillae of the tongue, have one of the most rapid tissue turnover rates in the mammalian body and are thought to be the source of squamous cell carcinoma of the tongue. However, the mechanism of tissue maintenance and regeneration is largely unknown for these cells. Here, we show that stem cells positive for Bmi1, keratin 14 and keratin 5 are present in the base but not at the very bottom of the interpapillary pit (observed most frequently in the second or third layer (position +2 or +3) from the basal cells). Using a multicolour lineage tracing method, we demonstrated that one stem cell per interpapillary pit survives long-term. The cells were shown to be unipotent stem cells for keratinized epithelial cells but not for taste bud cells, and were found to usually be in a slow-growing or resting state; however, on irradiation-induced injury, the cells rapidly entered the cell cycle and regenerated tongue epithelium. The elimination of Bmi1-positive stem cells significantly suppressed the regeneration. Taken together, these results suggest that the stem cells identified in this study are important for tissue maintenance and regeneration of the lingual epithelium.

Establishment of a Novel Lingual Organoid Culture System: Generation of Organoids Having Mature Keratinized Epithelium from Adult Epithelial Stem Cells

Despite the strong need for the establishment of a lingual epithelial cell culture system, a simple and convenient culture method has not yet been established. Here, we report the establishment of a novel lingual epithelium organoid culture system using a three-dimensional matrix and growth factors. Histological analyses showed that the generated organoids had both a stratified squamous epithelial cell layer and a stratum corneum. Very recently, we showed via a multicolor lineage tracing method that Bmi1-positive stem cells exist at the base of the epithelial basal layer in the interpapillary pit. Using our new culture system, we found that organoids could be generated by single Bmi1-positive stem cells and that in the established organoids, multiple Bmi1-positive stem cells were generated at the outermost layer. Moreover, we observed that organoids harvested at an early point in culture could be engrafted and maturate in the tongue of recipient mice and that the organoids generated from carcinogen-treated mice had an abnormal morphology. Thus, this culture system presents valuable settings for studying not only the regulatory mechanisms of lingual epithelium but also lingual regeneration and carcinogenesis.

Bmi1 expression in long-term germ stem cells

Asingle cells in undifferentiated spermatogonia are considered to be the most primitive forms of germ stem cells (GSCs). Although GFRα1 is thought to be a marker of Asingle cells, we found that Bmi1High is more specific than GFRα1 for Asingle cells. Bmi1High expression in Asingle cells is correlated with seminiferous stages, and its expression was followed by the proliferative stage of Asingle GSCs. In contrast, GFRα1 expression was seminiferous stage-independent. Fate analyses of EdU-positive Bmi1High-positive cell-derived Asingle cells revealed that these cells self-renewed or generated transient amplifying Apaired cells. Bmi1High-positive cells were resistant to irradiation-induced injury, after which they regenerated. Elimination of Bmi1High-positive cells from seminiferous tubules resulted in the appearance of tubules with seminiferous stage mismatches. Thus, in this study, we found that Bmi1High is a seminiferous stage-dependent marker for long-term GSCs and that Bmi1High-positive cells play important roles in maintaining GSCs and in regenerating spermatogenic progenitors after injury.

Two cases of gastrointestinal perforation after radiotherapy in patients receiving tyrosine kinase inhibitor for advanced renal cell carcinoma

We report two cases of gastrointestinal perforation (GIP) after radiotherapy in patients receiving tyrosine kinase inhibitor (TKI) for advanced renal cell carcinoma (RCC). Case 1 was a 61-year-old woman with lung metastases after a radical nephrectomy for a right RCC (cT3aN0M0) treated with interferon-alpha (OIF, 5 MIU, three times per week). She developed lytic metastases of the left femur and the left acetabulum. She was treated with palliative radiotherapy to the metastatic portion (3 Gy × 10 fractions), and 400 mg sorafenib twice per day plus continuing interferon alpha. She experienced sudden left lower abdominal pain after four weeks of treatment, and was diagnosed with a perforation of the sigmoid colon with fecal peritonitis. Case 2 was a 48-year-old man with lung, lymph node, and bone metastases after a radical nephrectomy for a right RCC (cT2N0M0), and was treated with 400 mg sorafenib twice per day. He developed lytic bone metastases of the lumbar vertebrae, which was treated with palliative radiotherapy to L2-4 (3 Gy × 10 fractions). He experienced sudden abdominal pain after two months of radiation treatment, and was diagnosed with a perforation of the sigmoid colon with fecal peritonitis. These cases underwent radiotherapy, and therefore this may be related to the radiosensitivity of TKI.

A renal epithelioid angiomyolipoma/perivascular epithelioid cell tumor with TFE3 gene break visualized by FISH

We present a case of renal epithelioid angiomyolipoma (eAML)/perivascular epithelioid cell tumor (PEComa) with a TFE3 gene break visible by fluorescence in situ hybridization (FISH). Histologically, the tumor was composed of mainly epithelioid cells forming solid arrangements with small foci of spindle cells. In a small portion of the tumor, neoplastic cells displayed nuclear pleomorphism, such as polygonal and enlarged vesicular nuclei with prominent nucleoli. Marked vascularity was noticeable in the background, and perivascular hyaline sclerosis was also seen. Immunohistochemically, neoplastic cells were diffusely positive for α-smooth muscle actin and melanosome in the cytoplasm. Nuclei of many neoplastic cells were positive for TFE3. FISH analysis of the TFE3 gene break using the Poseidon TFE3 (Xp11) Break probe revealed positive results. Reverse transcriptase-polymerase chain reactions (RT-PCR) for ASPL/TFE3, PRCC/TFE3, CLTC/TFE3, PSF/TFE3, and NonO/TFE3 gene fusions all revealed negative results. This is the first reported case of renal eAML/PEComa with a TFE3 gene break, and it has unique histological findings as compared to previously reported TFE3 gene fusion-positive PEComas. Pathologists should recognize that PEComa with TFE3 gene fusion can arise even in the kidney.

Laparoendoscopic single-site surgery for urachal remnants.

Urachal remnants are relatively rare but may potentially cause various symptoms and an increased risk for developing adenocarcinoma. Open or laparoscopic surgery is usually used for their resection. Laparoendoscopic single‐site surgery has been recently applied in several surgical procedures. This report describes two cases of vesicourachal diverticulum treated by resection using laparoendoscopic single‐site surgery.

Intestinal cancer stem cells marked by Bmi1 or Lgr5 expression contribute to tumor propagation via clonal expansion

Although the existence of cancer stem cells in intestine tumors has been suggested, direct evidence has not been yet provided. Here, we showed, using the multicolor lineage-tracing method and mouse models of intestinal adenocarcinoma and adenoma that Bmi1- or Lgr5- positive tumorigenic cells clonally expanded in proliferating tumors. At tumor initiation and during tumor propagation in the colon, the descendants of Lgr5-positive cells clonally proliferated to form clusters. Clonal analysis using ubiquitous multicolor lineage tracing revealed that colon tumors derived from Lgr5-positive cells were monoclonal in origin but eventually merged with neighboring tumors, producing polyclonal tumors at the later stage. In contrast, the origin of small intestine tumors was likely polyclonal, and during cancer progression some clones were eliminated, resulting in the formation of monoclonal tumors, which could merge similar to colon tumors. These results suggest that in proliferating intestinal neoplasms, Bmi1- or Lgr5-positive cells represent a population of cancer stem cells, whereas Lgr5-positive cells also function as cells-of-origin for intestinal tumors.

A novel risk stratification model, involving preoperative lymphocyte–monocyte ratio and standard pathological factors, for overall survival in patients with bladder cancer undergoing radical cystectomy

OBJECTIVE To evaluate the ability of preoperative lymphocyte-monocyte ratio to predict prognosis and determine post-operative risk stratification in patients with bladder cancer undergoing radical cystectomy. METHODS A retrospective review of the 210 patients who had undergone radical cystectomy for bladder cancer from 2006 to 2013 identified 181 patients with sufficient data to evaluate the prognostic significance of the lymphocyte-monocyte ratio. Overall survival was assessed by the Kaplan-Meier method. The association of clinicopathological findings with overall survival was evaluated by a multivariate Cox proportional model, and a novel risk stratification model to predict prognosis was established. RESULTS Median follow-up after radical cystectomy was 6.0 years. The 5-year overall survival rate was significantly lower for patients with low than high lymphocyte-monocyte ratio (27.6 vs 80.7%, P < 0.001). Multivariable analyses showed that pT ≥2, pN ≥1, positive margins and low lymphocyte-monocyte ratio were independent predictors of overall survival. A post-operative risk stratification model using these factors showed significant differences among the three subgroups (low, intermediate and high risk) with a concordance index of 0.84. The 5-year overall survival rates in patients at low, intermediate and high risk were 85.4, 45.5 and 0%, respectively (P < 0.001). CONCLUSIONS Preoperative lymphocyte-monocyte ratio, pathological tumor and lymph node stage and positive margins are significantly associated with overall survival in patients who have undergone radical cystectomy for bladder cancer.

Uninterrupted suturing of renal parenchyma in laparoscopic partial nephrectomy decreases renal ischemic time and intraoperative blood loss

We examined factors affecting renal ischemic time and intraoperative blood loss in laparoscopic partial nephrectomy and attempted to determine which method of suture for parenchymal closure is effective in this operation. Fifty‐seven patients who underwent laparoscopic partial nephrectomy were studied. Some variables and methods of suture for parenchymal closure were tested for independent effects on ischemic time and bleeding volume. Mean renal ischemic time and estimated blood loss were 38 min and 175 mL, respectively. Method of suture for parenchymal closure was the only factor independently associated with intraoperative blood loss less than 100 mL. Furthermore, uninterrupted suture for parenchymal closure was a significant factor associated with renal ischemic time less than 30 min. Renal ischemic time or intraoperative blood loss can be decreased by using uninterrupted suture for parenchymal defect.

Colonic adenocarcinoma and stones in an Indiana pouch

Abstract  We report on a 63‐year‐old woman with adenocarcinoma and stones in an Indiana pouch. Adenocarcinoma of an Indiana pouch is extremely rare. To our knowledge, only four cases with adenocarcinoma in an Indiana pouch have been reported.