[A Case of Locally Advanced Rectal Cancer with Invasion to Other Organs in Which Pathological Complete Response Was Obtained with Neoadjuvant Chemotherapy].

A 67-year-old man was admitted with melena. A colonoscopy detected advanced rectal cancer, and a CT scan revealed invasion of the seminal vesicle and prostate. Given the wild-type RAS status of the tumor, we administered 6 courses of XELOX plus cetuximab as neoadjuvant chemotherapy. After treatment, the tumor had shrunk, and the rectum had narrowed. Later, following a diagnosis of coronary artery disease, colostomy was performed. The patient was treated for the coronary artery disease for 2 months. Following treatment, tumor progression was detected, and hence, the patient was treated with the same chemotherapy regimen for 4 more courses. We performed a laparoscopic assisted abdominoperineal resection of the rectum with combined resection of the seminal vesicle and prostate. Pathological examination revealed a complete response to treatment. Six months after the operation, no recurrence was observed without further adjuvant chemotherapy.

IgG4-related disease manifesting the gastric wall thickening.

IgG4-related disease (IgG4-RD) is a recently designated disease entity and its full picture has not yet been elucidated. Here, we report an unusual case of a patient with gastric wall thickening secondary to IgG4-RD. A 68-year-old male visited our hospital with itchy skin lesions and an episode of organizing pneumonia. On the suspicion of malignancy-associated skin lesions, computed tomography (CT) was performed. The CT revealed prominent thickening of the gastric wall. Due to the possibility of malignancy, the patient underwent distal gastrectomy. Histopathological examination showed fibrosis of the submucosa and prominent thickening of the muscularis propria. Most of infiltrating cells were IgG4-positive plasma cells. Post-operative blood test revealed significantly high serum levels of total IgG and IgG4. Based on these histological features, the patient was given a definitive diagnosis of IgG4-RD. Further accumulation of cases like the present case that develop IgG4-RD with rare manifestations would lead to the elucidation of pathogenesis.

Atypical extraventricular neurocytoma in a 3-year-old girl: case report with radiological-pathological correlation.

BACKGROUND: Extraventricular neurocytoma (EVN) is a rare neuronal tumor histologically similar to central neurocytoma but arising in the brain parenchyma outside the ventricles. The minority of EVNs show atypical features including increased proliferative index, microvascular proliferation, or necrosis, and are called atypical EVN. Most of atypical EVNs occur in adults, and the tumors in children are extremely rare. A radiological-pathological correlation and radiological clue to atypical EVNs have not been clarified. CASE REPORT: We report a case of atypical EVN in a 3-year-old girl. Magnetic resonance imaging (MRI) revealed an extraventricular intraparenchymal tumor in the left frontal lobe, which was composed of homogeneous well-demarcated cystic component and peripheral ill-delineated solid component with enhancement. Angiography demonstrated vascular proliferation and arteriovenous shunting in the tumor. Histologically, the resected tumor was diagnosed as atypical EVN. Types of the tumor borders (well-circumscribed or infiltrative) and MRI findings correlated closely. Morphology of the tumor vasculature was remarkable for microvascular proliferation and dilated, thickened veins, which corresponded to the angiographic features. CONCLUSION: Although rare, atypical EVN should be included in the differential diagnosis of a cystic mass in the cerebral hemispheres in children. Radiological evaluation of tumor borders and angiographic characteristics might be useful for predicting atypicality of the tumor.

Galectin-7 and actin are components of amyloid deposit of localized cutaneous amyloidosis.

The precursor protein of localized cutaneous amyloidosis (LCA) is believed to be cytokeratins on the basis of previous immunohistochemical studies. To identify the candidate amyloid protein biochemically, amyloid proteins were extracted with distilled water from lesional skin of LCA associated with Bowen's disease. The proteins were resolved on one- or two-dimensional polyacrylamide gel electrophoresis followed by characterization with immunoblot analysis. The proteins with multiple molecular weights of 50-67 kDa and two proteins with 25 and 35 kDa were identified as keratins, serum amyloid P component and apolipoprotein E, respectively. The unknown 14-kDa (pI = 7.0) and 42-kDa (pI = 5.4) proteins reacted with the antibody against galectin-7 and actin, respectively. The protein with the molecular weight of 14 kDa was identified as galectin-7 by MALDI-TOF mass spectrometer. Their electrophoretic mobilities were identical with normal counterparts extracted from cultured normal human keratinocytes. Galectin-7 and actin were detected by immunoblot assay in the water-soluble fractions prepared from the lesional skins of two patients with primary LCA. Immunohistochemical studies of tumor-associated (n = 9) and primary (n = 10) LCA revealed various degrees of positive immunoreactivities with the antibodies for galectin-7 and F-actin. Galectin-7 and actin, which contain considerable amount of ß-sheet structure, may be candidate amyloidogenic proteins of primary and secondary LCA.

Non-sebaceous lymphadenoma of the salivary gland with serous acinic cell differentiation, a first case report in the literature.

We report an atypical case of non-sebaceous lymphadenoma (NSL) of the parotid gland showing serous acinic cell differentiation. NSL is a rare benign salivary gland tumor with intermingled lymphoid and epithelial tissues without sebaceous differentiation. Since the first description of a case designated by Auclair et al. as 'non-sebaceous lymphadenoma' in 1991, to our best knowledge, only 37 cases have been reported, and no differentiation of tumor cells into serous acinic cell lineage has been described so far. In this paper, we present a case of NSL with serous acinic cell differentiation. The patient was a 78-year-old female with the complaint of a painless mass in the left parotid gland. The surgically resected tumor was encapsulated and measured 13 × 9 × 9 mm. Histologically, the tumor had the features of NSL, and an unusual finding of this case was the presence of epithelial cells with serous acinic cell differentiation. Dense cytoplasm packed with basophilic granules in those cells was positive in periodic acid Schiff reaction after diastase digestion (D-PAS), which was compatible with the feature of serous acinic cell differentiation. Possible differentiation of the epithelial component into serous acinic cell in this rare entity is warranted to avoid confusion in the diagnosis.

[Case of primary lymphoplasmacytic lymphoma limited to the paratracheal mediastinum].

A 54 year old Japanese man was introduced to Saiseikai General hospital for an evaluation of an abnormal chest X-ray film. Abnormal soft tissue area was observed in the mediastinum surrounding anterior area of the trachea on chest CT. Because the mediastinal tumor showed slow enlargement after temporal decrease and surgical resection of the tumor was performed 3 years after the first visit. Pathologically, diffuse proliferation of oval-shaped plasmacytic or small lymphocytic cells with eccentrically-located nuclei with rough chromatin were observed in the tumor. Immunohistochemically, these cells were positive for CD20, weakly positive for IgM, negative for CD3, CD5, CD10, suggesting lymphoplasmacytic lymphoma (LPL). The patient was treated with rituximab after the surgical treatment, and showed no exacerbation for 3.5 years after surgery. LPL localized to the paratracheal mediastinum is rare, and a surgical approach is important for prompt and proper diagnosis.

[A case of rectal carcinoid tumor with lymph node and liver metastasis 5 years after curative resection].

A 65-year-old man was diagnosed with a rectal carcinoid tumor (10 mm in diameter) in July 2007. We performed low anterior resection with lymph node dissection. Histological depth of penetration of the rectal wall by the primary tumor was up to the submucosa, and lymph node metastasis was observed at station 251 (Japanese Classification of Colorectal Carcinoma, seventh Edition). Five years later, abdominal enhanced computed tomography (CT) revealed multiple liver tumors and swelling of the right obturator lymph nodes. During surgery, ultrasonography revealed 10 hypoechoic masses in both hepatic lobes. We performed right pelvic lymph node dissection, partial hepatectomy (S5/6, S7, and S8), and microwave coagulation therapy. After surgery, the patient was treated with octreotide long-acting repeatable( LAR). The patient remained disease-free for 10 months after surgery. Our findings suggest that careful monitoring is necessary for metachronous lymph node and liver metastasis during follow-up treatment for rectal carcinoid tumors.

Combined evaluation of CK5/6, ER, p63, and MUC3 for distinguishing breast intraductal papilloma from ductal carcinoma in situ.

The differentiation of intraductal papilloma (IDP) in the breast from ductal carcinoma in situ (DCIS) is sometimes difficult. Fifty papillary lesions (25 DCIS and 25 IDP) were immunohistochemically examined using a panel of antibodies, including CK5/6, ER, p63, Ki-67, chromogranin A, synaptophysin, neuron specific enolase, CD56, MUC1, MUC3, CD44, p21, p27, and p53. The immunohistochemical staining pattern of each antibody was evaluated using the Allred scoring system. Then, the area under curve (AUC) for each antibody was computed by receiver operating characteristic (ROC) analysis. DCIS typically showed high scores for ER and MUC3 reactivity compared with IDP, and the AUC for ER and MUC3 were 0.941 and 0.908, respectively. In contrast, IDP showed high scores for CK5/6 and p63 reactivity compared with DCIS, and the AUC for CK5/6 and p63 were 1.00 and 0.954, respectively. We devised a 'Differential Index' (DI) using the following formula: [S(ER) + S(MUC3)]/[S(CK5/6) + S(p63) + 1]. The distributions of the DI for IDP and DCIS did not overlap when the cutoff value was placed arbitrarily at DI = 1.0. From these results, it is concluded that a panel of four CK5/6, ER, p63, and MUC3 antibodies provide valuable information for differentiating IDP from DCIS.

Surgical resection of intraorbital metastasis of a gastrointestinal stromal tumor resistant to chemotherapy.

PURPOSE: We present a case of a gastrointestinal stromal tumor (GIST) metastasis of the rectal primary resisting chemotherapy to the right orbit 15 years after excision of the primary lesion. OBSERVATIONS: A 79-year-old man was diagnosed with rectal GIST at the age of 65 years and underwent rectal amputation. He underwent hepatectomy for GIST liver metastases at the age of 69 years and pericardiectomy for GIST pericardial metastases at 72 years of age. At the age of 79 years, positron emission tomography-computed tomography revealed the possibility of liver metastasis and metastasis to the right orbit of 10 mm in size. Magnetic resonance imaging revealed a well-circumscribed mass of 10 mm × 12 mm in the deep medial rectus muscle of the right orbit, which was referred to our department for ophthalmic examination. The latter revealed only mild abduction disorder in the right eye. Although chemotherapy was initiated, the tumor gradually increased, causing exophthalmos in the right eye, visual field impairment due to optic nerve exclusion, and decreased visual acuity. Due to repeated multiple metastases, the patient underwent right orbital exenteration and free flap reconstruction at the age of 83 years for radical cure. Pathological examination revealed c-Kit positive, CD34 positive, S100 protein minority positive, MIB-1 positive rate of 10% or more, and α-SMA negative, and the diagnosis was intraorbital metastasis of GIST. CONCLUSIONS AND IMPORTANCE: Orbital metastases in GISTs are extremely rare, and there is no established standard treatment. Therefore, a comprehensive decision must be made based on the final treatment goal and the patient's background when selecting treatment.

A glycyrrhizin-containing preparation reduces hepatic steatosis induced by hepatitis C virus protein and iron in mice.

BACKGROUND/AIM: A European randomized trial showed biochemical effects of 6-month treatment with Stronger Neo-Minophagen C (SNMC), a glycyrrhizin-containing preparation, in patients with chronic hepatitis C, but its underlying mechanisms remain elusive. We reported previously that SNMC exhibits an anti-oxidative effect in hepatitis C virus (HCV) transgenic mice that develop marked hepatic steatosis with mitochondrial injury under iron overloading. Hepatic steatosis and iron overload are oxidative stress-associated pathophysiological features in chronic hepatitis C. The aim of this study was to investigate whether long-term treatment with SNMC could prevent the development of hepatic steatosis in iron-overloaded HCV transgenic mice. METHODS: C57BL/6 transgenic mice expressing the HCV polyprotein were fed an excess iron diet concomitantly with intraperitoneal injection of saline, SNMC, or seven-fold-concentrated SNMC thrice weekly for 6 months. RESULTS: Stronger Neo-Minophagen C inhibited the development of hepatic steatosis in a dose-dependent manner without affecting hepatic iron content, attenuated ultrastructural alterations of mitochondria of the liver, activated mitochondrial ß-oxidation with increased expression of carnitine palmitoyl transferase I and decreased the production of reactive oxygen species in the liver in iron-overloaded transgenic mice. However, SNMC hardly affected the unfolded protein response, which post-transcriptionally activates sterol regulatory element-binding protein 1, a transcription factor involved in lipid synthesis, even though we reported previously the activation of the unfolded protein response in the same iron-overloaded transgenic mice. CONCLUSIONS: These results suggest that SNMC prevents hepatic steatosis possibly by protecting mitochondria against oxidative stress induced by HCV proteins and iron overload.

Siglec-7 is a predictive biomarker for the efficacy of cancer vaccination against metastatic colorectal cancer.

Cancer immunotherapy, including vaccination, is considered a major scientific and medical breakthrough. However, cancer immunotherapy does not result in durable objective responses against colorectal cancer (CRC). To improve the efficacy of immunotherapy, the present study investigated several biomarkers for selecting patients who were expected to respond well to immunotherapy. Firstly, a comprehensive proteomic analysis was performed using tumor tissue lysates from patients enrolled in a phase II study, in which five human leukocyte antigen (HLA)-A*24:02-restricted peptides were administered. Sialic acid-binding immunoglobulin type lectin (Siglec)-7 was identified as a potential predictive biomarker. Subsequently, this biomarker was validated using western blot analysis, and immunofluorescence using tissue samples from the patients enrolled in the phase II study. The expression levels of Siglec-7 detected by immunofluorescence were quantified and their association with overall survival (OS) in patients treated with the peptide vaccine was examined. Furthermore, considering the important role of tumor-infiltrating lymphocytes (TILs) for CRC prognosis, the densities of CD3+, CD4+, CD8+ and forkhead box P3 (FOXP3)+ T cells in CRC tissues were examined and compared with Siglec-7 expression. The mean expression levels of Siglec-7 were significantly higher in patients with poor prognosis, with an OS of ≤2 years, as shown in comprehensive proteomic analysis (P=0.016) and western blot analysis (P=0.025). Immunofluorescence analysis demonstrated that Siglec-7 was expressed in intratumoral macrophages. The OS in patients with high Siglec-7 expression was significantly shorter than in that in patients with low Siglec-7 expression (P=0.017) in the HLA-A*24:02-matched patients. However, this difference was not observed in the HLA-unmatched patients. There was no significant difference in OS between patients according to the numbers of TILs, nor significant correlation between TILs and Siglec-7 expression. In conclusion, Siglec-7 expression in macrophages in tumor tissue may be a novel predictive biomarker for the efficacy of immunotherapy against metastatic CRC.

Proteomic analysis of proteins expressing in regions of rat brain by a combination of SDS-PAGE with nano-liquid chromatography-quadrupole-time of flight tandem mass spectrometry.

BACKGROUND: Most biological functions controlled by the brain and their related disorders are closely associated with activation in specific regions of the brain. Neuroproteomics has been applied to the analysis of whole brain, and the general pattern of protein expression in all regions has been elucidated. However, the comprehensive proteome of each brain region remains unclear. RESULTS: In this study, we carried out comparative proteomics of six regions of the adult rat brain: thalamus, hippocampus, frontal cortex, parietal cortex, occipital cortex, and amygdala using semi-quantitative analysis by Mascot Score of the identified proteins. In order to identify efficiently the proteins that are present in the brain, the proteins were separated by a combination of SDS-PAGE on a C18 column-equipped nano-liquid chromatograph, and analyzed by quadrupole-time of flight-tandem-mass spectrometry. The proteomic data show 2,909 peptides in the rat brain, with more than 200 identified as region-abundant proteins by semi-quantitative analysis. The regions containing the identified proteins are membrane (20.0%), cytoplasm (19.5%), mitochondrion (17.1%), cytoskeleton (8.2%), nucleus (4.7%), extracellular region (3.3%), and other (18.0%). Of the identified proteins, the expressions of glial fibrillary acidic protein, GABA transporter 3, Septin 5, heat shock protein 90, synaptotagmin, heat shock protein 70, and pyruvate kinase were confirmed by immunoblotting. We examined the distributions in rat brain of GABA transporter 3, glial fibrillary acidic protein, and heat shock protein 70 by immunohistochemistry, and found that the proteins are localized around the regions observed by proteomic analysis and immunoblotting. IPA analysis indicates that pathways closely related to the biological functions of each region may be activated in rat brain. CONCLUSIONS: These observations indicate that proteomics in each region of adult rat brain may provide a novel way to elucidate biological actions associated with the activation of regions of the brain.

Induced expression of GINS complex is an essential step for reactivation of quiescent stem-like tumor cells within the peri-necrotic niche in human glioblastoma.

PURPOSE: Glioblastoma is still intractable despite the progress in therapies, and the intractability is attributable to a minor population of stem-like tumor cells. As a niche harboring quiescent stem-like tumor cells with potentially high tumorigenicity, we have specified an area around large ischemic necrosis, termed 'peri-necrotic niche', in glioblastoma. In this study, the behavior of tumor cells inside and outside the peri-necrotic niche was analyzed to find out molecules responsible for reactivation of quiescent stem-like tumor cells to proliferate outside the niche. METHODS: Expression of Ki-67 and GINS complex composed of SLD5, PSF1, PSF2 and PSF3 was analyzed by immunohistochemistry in human glioblastoma tissue samples. Proliferation assays, immunoblotting and siRNA experiments were performed using a glioblastoma cell line. RESULTS: Immunohistochemical analysis revealed quiescent and proliferative phenotypes of tumor cells inside and outside the niche, respectively, and the proliferation was spatially correlated with the expression of GINS components in tumor cells. To mimic the tissue microenvironment inside versus outside the niche, glioblastoma cells were cultured under hypoxic versus normoxic conditions, or without versus with serum. Quiescence and proliferation of tumor cells were reversibly determined by the microenvironment inside and outside the niche, respectively, and proliferative activities paralleled the expression levels of GINS components. Furthermore, the reactivation of proliferation after reoxygenation or serum replenishment was suppressed in quiescent tumor cells with PSF1 knockdown. CONCLUSIONS: These findings indicate the essential role of GINS complex in the switch between quiescence and proliferation of tumor cells inside and outside the peri-necrotic niche.

Gastrointestinal manifestation of immunoglobulin G4-related disease: clarification through a multicenter survey.

BACKGROUND: Several reports on immunoglobulin (Ig)G4-related disease (IgG4-RD) with gastrointestinal involvement (IgG4-related gastrointestinal disease; IgG4-GID) have been published, although this entity has not been fully established clinicopathologically. Thus, we carried out a multicenter survey. METHODS: Patients with possible IgG4-GID who underwent resection were collected. Histologic slides were reevaluated, and eight cases with diffuse lymphoplasmacytic infiltration but without numerous neutrophils, granulations or epithelioid granulomas were further analyzed. RESULTS: Overall, the IgG4 counts (87-345/high-power field) and IgG4/IgG-positive ratio were high (44-115%). The demographic findings included advanced age among the patients (55-80 years) and male preponderance (six cases). Six lesions (five gastric, one esophageal), consisting of lymphoplasmacytic infiltration with neural involvement in the muscularis propria and/or bottom-heavy plasmacytosis in the gastric mucosa, were histologically regarded as highly suggestive of IgG4-RD. Storiform fibrosis and obliterative phlebitis were found in two cases, and the former gave rise to a 7-cm-sized inflammatory pseudotumor (IPT) in one case. Ulceration and carcinoma co-existed in three and two lesions, respectively. All the patients had other organ involvement (OOI), and serum IgG4 levels were markedly elevated (four of five patients). The remaining two cases with gastric IPTs featuring reactive nodular fibrous pseudotumor or nodular lymphoid hyperplasia were regarded as possible cases of IgG4-RD because of the histologic findings and lack of OOI. CONCLUSIONS: IgG4-GID is found in the setting of IgG4-RD, often with ulceration or cancer. Characteristic histologic findings are observed in the muscularis propria and gastric mucosa. Cases with IPT may be heterogeneous, and there may be mimickers of IgG4-GID.

Experimental AA amyloidosis in mice is inhibited by treatment with triptolide, a purified traditional Chinese medicine.

The effect of triptolide, which is isolated from Tripterygium Wilfordii, on induction and development of murine AA amyloidosis was studied. In the first experiment, we examined the ability of triptolide to inhibit initiation of amyloidosis. Oral or intraperitoneal administration of 480 microg/kg/day triptolide inhibited splenic amyloid deposition in both rapid and chronic induction models of mouse AA amyloidosis. Moreover, serum amyloid A (SAA) and interleukin (IL)-6 levels were also suppressed remarkably. Triptolide also immediately decreased SAA levels and reduced the incidence of amyloidosis even under conditions of high SAA levels. In the second experiment, we evaluated the influence of triptolide on development and resorption of amyloid deposition. Amyloid deposition was induced in mice by 28 daily injections of casein. After splenic and hepatic biopsies to confirm the presence of amyloid deposits, the mice immediately started to receive daily injections of 480 microg/kg/day triptolide with or without casein. Treatment with triptolide for 35 days and 105 days prevented deposition of amyloid and promoted resorption of splenic amyloid deposits. In conclusion, we show for the first time that triptolide inhibits induction and development of experimental murine amyloidosis. These results suggest that through suppression of IL-6, triptolide can reduce production of SAA. Amyloid deposition is prevented when levels of the amyloid-forming precursor protein SAA are decreased significantly.

Autopsy case of the C12orf65 mutation in a patient with signs of mitochondrial dysfunction.

OBJECTIVE: To describe the autopsy case of a patient with a homozygous 2-base deletion, c171_172delGA (p.N58fs), in the C12orf65 gene. METHODS: We described the clinical history, neuroimaging data, neuropathology, and genetic analysis of the patients with C12orf65 mutations. RESULTS: The patient was a Japanese woman with a history of delayed psychomotor development, primary amenorrhea, and gait disturbance in her 20s. She was hospitalized because of respiratory failure at the age of 60. Pectus excavatum, long fingers and toes, and pes cavus were revealed by physical examination. Her IQ score was 44. Neurologic examination revealed ophthalmoplegia, optic atrophy, dysphagia, distal dominant muscle weakness and atrophy, hyperreflexia at patellar tendon reflex, hyporeflexia at Achilles tendon reflex, and extensor plantar reflexes. At age 60, she died of pneumonia. Lactate levels were elevated in the patient's serum and CSF. T2-weighted brain MRI showed symmetrical hyperintense brainstem lesions. At autopsy, axial sections exposed symmetrical cyst formation with brownish lesions in the upper spinal cord, ventral medulla, pons, dorsal midbrain, and medial hypothalamus. Microscopic analysis of these areas demonstrated mild gliosis with rarefaction. Cell bodies in the choroid plexuses were eosinophilic and swollen. Electron microscopic examination revealed that these cells contained numerous abnormal mitochondria. Whole-exome sequencing revealed the 2-base deletion in C12orf65. CONCLUSIONS: We report an autopsy case of the C12orf65 mutation, and findings suggest that mitochondrial dysfunction may underlie the unique clinical presentations.

Stroma-poor Warthin's tumor with significant oncocytic hyperplasia: case presentation and considerations regarding its histogenesis.

Although Warthin's tumor is one of the common tumors of the salivary glands, Warthin's tumors with a prominent component of nodular oncocytic hyperplasia reminiscent of oncocytoma are rare. Here we report such a tumor, measuring 3 cm in diameter, found in the parotid gland of an 81-year-old man. Histologically, approximately 70% of the mass was a component of nodular oncocytic proliferation, and the remaining portion was a component of conventional Warthin's tumor. We performed immunohistochemical analysis to explore what factors determined the morphogenesis of the two components in the single mass. Cytokeratin (CK) 5÷6-positive tumor cells, which represent basal cells, were aligned in a layer in the conventional Warthin's tumor component, whereas they were localized around blood vessels in the nodular oncocytic hyperplasia component. Immunostaining for CD34 showed that capillaries were sparsely present beneath the bilayered epithelia in the former component, while blood vessels resembling sinusoids separated the trabeculae of the tumor cells in the latter component. Ki-67 labeling index was slightly higher in the latter component. Double immunostaining for CK5÷6 and Ki-67 revealed that most of Ki-67-positive proliferating tumor cells were CK5÷6-positive, suggesting that CK5÷6-positive population contained proliferative progenitor cells of the tumor. These findings imply that the regional difference in the distribution pattern and proliferative activity of CK5÷6-positive putative progenitor cells along with the difference in the pattern of vascular network occurred during the tumorigenic process of the tumor and determined one region to become conventional Warthin's tumor morphology and the other to become nodular oncocytic hyperplasia.

Histological Characterization of the Tumorigenic "Peri-Necrotic Niche" Harboring Quiescent Stem-Like Tumor Cells in Glioblastoma.

BACKGROUND: Characterization of the niches for stem-like tumor cells is important to understand and control the behavior of glioblastomas. Cell-cycle quiescence might be a common mechanism underlying the long-term maintenance of stem-cell function in normal and neoplastic stem cells, and our previous study demonstrated that quiescence induced by hypoxia-inducible factor (HIF)-1α is associated with a high long-term repopulation capacity of hematopoietic stem cells. Based on this, we examined human astrocytoma tissues for HIF-1α-regulated quiescent stem-like tumor cells as a candidate for long-term tumorigenic cells and characterized their niche histologically. METHODS: Multi-color immunohistochemistry was used to visualize HIF-1α-expressing (HIF-1α+) quiescent stem-like tumor cells and their niche in astrocytoma (WHO grade II-IV) tissues. This niche was modeled using spheroids of cultured glioblastoma cells and its contribution to tumorigenicity was evaluated by sphere formation assay. RESULTS: A small subpopulation of HIF-1α+ quiescent stem-like tumor cells was found in glioblastomas but not in lower-grade astrocytomas. These cells were concentrated in the zone between large ischemic necroses and blood vessels and were closer to the necrotic tissues than to the blood vessels, which suggested that a moderately hypoxic microenvironment is their niche. We successfully modeled this niche containing cells of HIF-1α+ quiescent stem-like phenotype by incubating glioblastoma cell spheroids under an appropriately hypoxic condition, and the emergence of HIF-1α+ quiescent stem-like cells was shown to be associated with an enhanced sphere-forming activity. CONCLUSIONS: These data suggest that the "peri-necrotic niche" harboring HIF-1α+ quiescent stem-like cells confers a higher tumorigenic potential on glioblastoma cells and therefore may be a therapeutic target to control the behavior of glioblastomas.

Epithelioid/rhabdoid glioblastoma: a highly aggressive subtype of glioblastoma.

Epithelioid glioblastoma (GBM) and rhabdoid GBM are rare variants that are morphologically similar, but there is no consensus on the characteristics of each disease. These tumors have aggressive features of early recurrence and leptomeningeal dissemination and tend to develop in younger patients compared to typical GBM. The prognosis is normally worse than typical GBM, even with intensive chemoradiotherapy after surgical resection. Thus, accurate diagnosis and effective therapy for epithelioid/rhabdoid GBM are required. Four consecutive patients aged 16-48 years were diagnosed with epithelioid/rhabdoid GBM by pathological and immunohistochemical analysis at Yamaguchi University Hospital from 2006 to 2012. Two of these patients had relatively long-term survival (19 and 23 months after diagnosis). Two cases had a BRAF V600E mutation, whereas no ATRX mutation was present in any cases. All patients suffered leptomeningeal and/or spinal dissemination that worsened their prognosis. These results illustrate the need for a new therapeutic approach, such as molecular targeted drug therapy like BRAF inhibition, in addition to standard chemoradiotherapy for typical GBM.