Biomedical subjects

Masazumi Tsuneyoshi

Publications and source records attributed to Masazumi Tsuneyoshi.

At least 19 recordsLinked to original sources

PubMed2007

Hedgehog signaling pathway is a possible therapeutic target for gastric cancer.

BACKGROUND AND OBJECTIVES: It has been shown that the hedgehog (Hh) signaling pathway is activated in gastric cancer. To investigate the viability of the Hh pathway as a therapeutic target, we analyzed activation of the Hh pathway in gastric cancer. METHODS: Surgically resected gastric carcinoma specimens and lymph nodes were analyzed immunohistochemically. We used the percentage of cancer cells with nuclear translocation of Gli1 as a marker of Hh pathway activation. RESULTS: Nuclear localization of Gli1 was higher in 28 undifferentiated-type tumors than in 30 differentiated-type tumors. Eighteen of the fifty-eight cancer specimens consisted of a mixture of a histologically predominant part and a small area with different histology. In these 18 tumors, the percentage of cells showing nuclear staining of Gli1 was higher in the undifferentiated-type part than in the differentiated-type part. Nuclear staining of Gli1 in primary tumors was positively correlated with lymph node metastasis. The Gli1 nuclear staining percentage of metastatic lymph nodes correlated closely with that of each primary carcinoma. Cyclopamine, a Hh pathway inhibitor, suppressed the growth of gastric cancer cells in vitro. CONCLUSIONS: The Hh pathway may be a useful therapeutic target for such as undifferentiated-type gastric cancer with lymph node metastasis.

Adenocarcinoma↗

PubMed2007

Dysadherin expression as a significant prognostic factor and as a determinant of histologic features in synovial sarcoma: special reference to its inverse relationship with E-cadherin expression.

Dysadherin is a cancer-associated cell membrane glycoprotein, which down-regulates E-cadherin and promotes metastasis. Synovial sarcoma is a very rare mesenchymal tumor that exhibits an epithelial profile. To confirm the diagnosis of synovial sarcoma, we evaluated several immunohistochemical markers, or detected SYT-SSX fusion gene transcript. We studied the clinicopathologic features in 92 synovial sarcoma patients and also assessed the immunohistochemical expression of dysadherin and E-cadherin to examine their possible association with histologic subtype and biologic behavior. Moreover, among 30 patients, for whom frozen materials were available, dysadherin mRNA expression was examined by reverse transcription-polymerase chain reaction and real-time quantitative reverse transcription-polymerase chain reaction analysis. Dysadherin-positive expression was significantly correlated with E-cadherin-reduced expression (P=0.0004). Dysadherin-positive immunostaining was diffusely observed in the membranes of tumor cells in 30/68 (44%) patients with monophasic fibrous type and in 1/2 (50%) patients with poorly differentiated type. However, in biphasic tumors, dysadherin expression in the fibrous component was not diffusely observed, but often sporadically or focally observed [20/22 (91%) patients]. In addition, dysadherin mRNA expression in monophasic fibrous type was significantly higher than in biphasic type (P=0.0079). Synovial sarcoma patients with dysadherin expression survived for a significantly shorter time than those without dysadherin expression (P=0.0006). Patients with combined dysadherin-positive expression and E-cadherin-reduced expression had a significantly worse prognosis than those with other combinations of dysadherin and E-cadherin expression (P=0.0007). SYT-SSX fusion gene transcript was detected in 39 patients. In our series, SYT-SSX fusion type was found to have no correlation with histologic subtype, prognosis, or dysadherin expression. In multivariate analysis, dysadherin immunopositivity (P=0.0411) was an independent adverse prognostic factor, in addition to a high MIB-1 labeling index (> or =10%). We conclude that E-cadherin dysfunction by dysadherin is associated with reduced E-cadherin expression and morphologic change from epithelioid to spindle phenotype. Dysadherin expression is considered to be one of the determinants of histologic subtype in synovial sarcoma. Moreover, dysadherin expression is an excellent and independent prognostic indicator.

Adult↗

PubMed2006

Adventitial cystic disease of the popliteal vein: report of a case.

Adventitial cystic disease (ACD), also known as cystic mucoid or myxomatous degeneration, is a rare vascular disease seen mainly in arteries. It is very unusual for these cystic masses to develop in a vein. We report the case of a 56-year-old woman with leg swelling caused by ACD arising in the popliteal vein. The swelling appeared after a long period of standing. Magnetic resonance imaging (MRI) showed a popliteal cystic mass and venography showed disrupted venous flow. We resected the cyst wall without venous reconstruction, after which venous blood flow normalized and her symptoms subsided. To our knowledge, this is only the third documented case of ACD arising in the popliteal vein. A misdiagnosis could easily have been made, since the mass was not obvious on physical examination and the only symptom was intermittent swelling. Thus, it is important to be aware of ACD as a possible diagnosis when examining patients with a swelling in the leg.

Adult↗

PubMed2006

Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphoma: a clinicopathologic and molecular study with reference to antibiotic treatment.

BACKGROUND: The majority of gastric mucosa-associated lymphoid tissue (MALT) lymphoma develops in Helicobacter pylori-associated chronic gastritis. Little is still known regarding the clinicopathologic features of gastric MALT lymphoma not associated with H. pylori infection. METHODS: One hundred thirty-seven patients with gastric MALT lymphoma, in whom H. pylori status was evaluated using at least both serology and histology, were enrolled. Clinical, histopathologic, and molecular findings were compared between H. pylori-negative group (n = 12; 9%) and H. pylori-positive group (n = 125; 91%). t(11;18)(q21;q21) was investigated by reverse-transcription polymerase chain reaction and interphase fluorescence in situ hybridization. RESULTS: In cases without diffuse large B-cell lymphoma (DLBCL) component, H. pylori-negative lymphomas located more frequently in the proximal stomach (70%), less frequently appeared as superficial type (40%), and frequently invaded the submucosa or beyond (70%). Histologically, lymphoepithelial lesions (57%), lymphoid follicles (43%), and background mucosal atrophy (50%) in the H. pylori-negative group were less frequent than in the H. pylori-positive group (91%, 93%, and 100%, respectively). The frequencies of t(11;18)(q21;q21) (100%) and BCL10 nuclear expression (100%) in the H. pylori-negative group were significantly higher than in the H. pylori-positive group (2% and 27%, respectively). Response to antibiotic treatment was observed not only in the H. pylori-positive group (75%), but also in the H. pylori-negative group (2 of 7 patients, 29%). In cases with a DLBCL component, such differences were not observed between the 2 groups. CONCLUSIONS: H. pylori-negative gastric MALT lymphoma is characterized by frequent t(11;18)(q21;q21). Antibiotic treatment should be considered also for this disease, although cases with t(11;18)(q21;q21) may need additional strategies.

Adolescent↗

PubMed2006

Intramucosal gastric adenocarcinoma of poorly differentiated type in the young is characterized by Helicobacter pylori infection and antral lymphoid hyperplasia.

The aim of this investigation was to clarify the histological characteristics of gastric cancer in the young. Twenty-three surgically resected specimens of young patients (under 30 years of age; young group) with intramucosal cancer of poorly differentiated type and 42 surgically resected specimens of elderly patients (more than 40 years of age; elderly group) with tumors of the identical depth and histological type were examined. The degree of gastritis and Helicobacter pylori (H. pylori) infection was evaluated according to the updated Sydney system. The incidence of H. pylori infection was significantly higher in the young group than in the elderly group (96 vs 36%, P<0.05). Within the background mucosa, antral chronic inflammatory infiltrates with lymphoid-follicle hyperplasia were more severe, and intestinal metaplasia was less frequent in the young group than in the elderly group. Glandular atrophy was not different between the two groups. Intramucosal gastric adenocarcinomas of poorly differentiated type in the young may be associated with H. pylori infection with antral chronic inflammation with lymphoid-follicle hyperplasia, regardless of the existence of intestinal metaplasia within the background gastric mucosa.

Adenocarcinoma↗

PubMed2006

S100A11, a putative tumor suppressor gene, is overexpressed in pancreatic carcinogenesis.

PURPOSE: Recent microarray analyses revealed that expression of S100A11 is up-regulated in pancreatic cancer. The aim of the present study was to evaluate the association of S100A11 with pancreatic carcinogenesis. EXPERIMENTAL DESIGN: We measured S100A11 mRNA expression in various clinical samples related to pancreatic cancer and its precursor lesions, intraductal papillary mucinous neoplasm (IPMN) and pancreatic intraepithelial neoplasia, by quantitative reverse transcription-PCR. RESULTS: Levels of S100A11 were significantly higher in pancreatic cancer (n=22) and IPMN (n=18) bulk tissues than in nonneoplastic bulk tissues (n=22; P<0.0001 for both). Levels of S100A11 did not differ between pancreatic cancer and IPMN bulk tissues. In microdissection analyses, however, IPMN cells (n=21) expressed significantly higher levels of S100A11 than did cancer cells (n=23; P=0.003). The median level of S100A11 expression was higher in pancreatic intraepithelial neoplasia cells (n=6) than in cancer cells. In pancreatic juice analyses, cancer-related (n=24; P=0.004) and IPMN-related (n=18; P=0.001) juice expressed significantly higher levels of S100A11 than did chronic pancreatitis-related juice (n=23). CONCLUSIONS: The present data suggest that expression of S100A11, a putative tumor suppressor gene, is increased in the early stage of pancreatic carcinogenesis and decreased during subsequent progression to cancer. Analysis of the S100A11 level in pancreatic juice may be an effective tool for screening of patients with high-risk lesions that could progress to pancreatic cancer or detecting early-stage pancreatic cancer.

Carcinoma↗

PubMed2006

S100P is an early developmental marker of pancreatic carcinogenesis.

PURPOSE: Our goal was to clarify the involvement and clinical significance of S100P in pancreatic carcinogenesis. EXPERIMENTAL DESIGN: We examined S100P expression in 45 bulk pancreatic tissues; in microdissected cells, including invasive ductal carcinoma (IDC) cells (20 sections), pancreatic intraepithelial neoplasia (PanIN) cells (12 sections), intraductal papillary mucinous neoplasm (IPMN) cells (19 sections), and normal epithelial cells (11 sections); and in pancreatic juice samples from 99 patients with pancreatic diseases (32 cancer, 35 IPMN, and 32 chronic pancreatitis samples). We used quantitative real-time reverse transcription-PCR with gene-specific priming to measure S100P in these various types of samples. RESULTS: In bulk tissue analyses, pancreatic cancer and IPMN expressed significantly higher levels of S100P than did nonneoplastic pancreas (P<0.017 and P=0.0013, respectively). Microdissection analyses revealed that IPMN expressed significantly higher levels of S100P than did IDC (P<0.0001) and PanIN (P=0.0031), although S100P expression did not differ between IDC and PanIN (P=0.077). In pancreatic juice analyses, cancer and IPMN juice expressed significantly higher levels of S100P than did pancreatitis juice (both P<0.0001). Receiver operating characteristic curve analyses revealed that measurement of S100P in pancreatic juice was useful for discriminating neoplastic disease from chronic pancreatitis (area under the curve=0.837; 95% confidence interval, 0.749-0.903). CONCLUSION: S100P may be an early developmental marker of pancreatic carcinogenesis, and measurement of S100P in pancreatic juice may be useful for early detection of pancreatic cancer or screening of early pancreatic carcinogenesis.

Adenocarcinoma, Mucinous↗

PubMed2006

High expression of insulin-like growth factor binding protein-3 is correlated with lower portal invasion and better prognosis in human hepatocellular carcinoma.

Insulin-like growth factor binding protein-3 (IGFBP-3) modulates cell proliferation of various cancer cell types. However, it remains unclear how IGF-IGFBP-3-signaling is involved in growth and progression of hepatocellular carcinoma (HCC). The aim of the present study was to evaluate the role of IGFBP-3 in HCC. Type 1 receptor for IGF (IGF-1R) was expressed at various levels in the seven lines examined, but IGF-2R was not expressed. Of the seven lines, the growth of HAK-1B, KIM-1, KYN-2 and HepG2 cells was stimulated in a dose-dependent manner by the exogenous addition of IGF-I or IGF-II, but the HAK-1A, KYN-1 and KYN-3 cell lines showed no growth. Exogenous addition of IGFBP-3 markedly blocked IGF-I and IGF-II-stimulated cell growth of KYN-2 and HepG2 cells, and moderately stimulated that of KIM-1 and HAK-1B cells, but no growth of the KYN-1, KYN-3 and HAK-1A cell lines was observed. IGF-I enhanced the phosphorylation of IGF-1R, Akt and Erk1/2 in KYN-2 cells, and coadministration of IGFBP-3 blocked all types of activation by IGF-I investigated here. In contrast, no such activation by IGF-I was detected in KYN-3 cells. IGFBP-3 also suppressed IGF-I-induced cell invasion by KYN-2 cells. Moreover, we were able to observe the apparent expression of IGFBP-3 in KYN-3 cells, but not in the other six cell lines. Furthermore reduced expression of IGFBP-3, but not that of IGF-1R, was significantly correlated with tumor size, histological differentiation, capsular invasion and portal venous invasion. Low expression of IGFBP-3 was independently associated with poor survival. IGFBP-3 could be a molecular target of intrinsic importance for further development of novel therapeutic strategy against HCC.

Aged↗

PubMed2006

Characteristic differences according to the cirrhotic pattern of advanced primary biliary cirrhosis: Macronodular cirrhosis indicates slow progression.

It is important to evaluate advanced primary biliary cirrhosis (PBC) clinicopathologically to clarify its progressive mechanism. According to the cirrhotic pattern, 26 cases of explanted PBC were classified into non-cirrhotic (n=4), macronodular (n=4), mixed nodular (n=6), and micronodular cirrhosis (n=12), to compare their clinical and morphological features. In addition, the degree of preserved intrahepatic bile ducts and other histologic features were analyzed. Patients at living donor liver transplantation (LDLT) in the macronodular cirrhosis were significantly older than those in the micronodular cirrhosis. The mean duration between clinical presentation and LDLT in the macronodular cirrhosis was significantly longer than in the micronodular cirrhosis. The non-cirrhotic group showed a short duration between clinical presentation and LDLT. The ratio of explanted liver volume to standard liver volume (ELV/SLV) indicates that macronodular cirrhosis revealed more atrophic change than that in the other three types. The density of remnant intrahepatic bile ducts of less than 50mum per group in cases of macronodular cirrhosis was significantly higher than that in cases of micronodular cirrhosis. Therefore, different cirrhotic patterns of advanced PBC were correlated with the disease progression and the degree of bile duct disappearance. The macronodular cirrhotic patients were older, had a longer disease course, yet had less bile duct loss. We suggest that macronodular cirrhosis and micronodular cirrhosis of PBC are different type of PBC.

Journal Article↗

PubMed2006

Intramuscular diffuse-type giant cell tumor within the hamstring muscle.

Diffuse-type giant cell tumor (D-TGCT) is known as a synonym for pigmented villonodular synovitis (PVS), a condition usually found in the large joints. We report an extremely rare case of D-TGCT which was located within the hamstring muscle. The lesion was an incidental finding in a 62-year-old man who underwent positron emission tomography (PET) as part of a staging evaluation for gastric cancer. The lesion was resected. There has been neither metastasis nor recurrence during the 6-month period since resection. This case demonstrates that PVS/D-TGCT may have a high SUV on PET imaging, and for this reason PET may be useful for detecting both the tumor and any recurrence.

Buttocks↗

PubMed2006

Nuclear factor-kappaB contributes to hedgehog signaling pathway activation through sonic hedgehog induction in pancreatic cancer.

The hedgehog (Hh) signaling pathway, which functions as an organizer in embryonic development, is implicated in the development of various tumors. In pancreatic cancer, pathway activation is reported to result from aberrant expression of the ligand, sonic Hh (Shh). However, the details of the mechanisms regulating Shh expression are not yet known. We hypothesized that nuclear factor-kappaB (NF-kappaB), a hallmark transcription factor in inflammatory responses, contributes to the overexpression of Shh in pancreatic cancer. In the present study, we found a close positive correlation between NF-kappaB p65 and Shh expression in surgically resected pancreas specimens, including specimens of chronic pancreatitis and pancreatic adenocarcinoma. We showed that blockade of NF-kappaB suppressed constitutive expression of Shh mRNA in pancreatic cancer cells. Further activation of NF-kappaB by inflammatory stimuli, including interleukin-1beta, tumor necrosis factor-alpha, and lipopolysaccharide, induced overexpression of Shh, resulting in activation of the Hh pathway. Overexpression of Shh induced by these stimuli was also suppressed by blockade of NF-kappaB. NF-kappaB-induced Shh expression actually activated the Hh pathway in a ligand-dependent manner and enhanced cell proliferation in pancreatic cancer cells. In addition, inhibition of the Hh pathway as well as NF-kappaB suppressed the enhanced cell proliferation. Our data suggest that NF-kappaB activation is one of the mechanisms underlying Shh overexpression in pancreatic cancer and that proliferation of pancreatic cancer cells is accelerated by NF-kappaB activation in part through Shh overexpression.

Animals↗

PubMed2006

Dedifferentiated chondrosarcoma with leukocytosis and elevation of serum G-CSF. A case report.

BACKGROUND: G-CSF is known to function as a hematopoietic growth factor and it is known to be responsible for leukocytosis. G-CSF-producing tumors associated with leukocytosis include various types of malignancies. CASE PRESENTATION: We report the case of a 72-year-old man with dedifferentiated chondrosarcoma characterized by dedifferentiated components of malignant fibrous histiocytoma- or osteosarcoma-like features in addition to conventional chondrosarcoma, arising from his pelvic bone. After hemipelvectomy, when local recurrence and metastasis were identified, leukocytosis appeared and an elevated level of serum granulocyte-colony-stimulating factor (G-CSF) was also recognized. The patient died of multiple organ failure 2 months after surgery. Autopsy specimens showed that the histological specimens of the recurrence and metastasis were dedifferentiated components, without any conventional chondrosarcoma components. G-CSF was expressed only in the dedifferentiated components, not in the chondrosarcoma components, immunohistochemically. CONCLUSION: This is the first report of chondrosarcoma, or any other primary bone tumor, with leukocytosis, probably stimulated by tumor-produced G-CSF from the dedifferentiated components.

Journal Article↗

PubMed2006

Extremely well-differentiated adenocarcinoma of the stomach: clinicopathological and immunohistochemical features.

AIM: Minimal deviation carcinoma of the uterine cervix, otherwise known as extremely well-differentiated adenocarcinoma (EWDA), is characterized by its benign microscopic appearance in contrast to its aggressive behavior. In order to elucidate the clinicopathological features and biological behavior of the gastric counterpart of EWDA, we, using immunohistochemistry, analyzed nine lesions for the phenotypic expression, proliferative activity, and the expression of oncogene-associated products. METHODS: Clinicopathological features, including pre-operative biopsy diagnosis, were reviewed. Using immunohistochemistry, Ki-67 labeling index and expression of p53 and c-erbB-2 protein in the gastric lesions were detected. RESULT: Locations in the middle or upper third of the stomach and polypoid macroscopic features are characteristic of EWDA of the stomach. Although 4 of the 9 lesions showed only focal lymphatic or venous invasion, lymph node metastasis was not present and none of the patients died of the lesions (mean follow-up period, 56 mo). All 9 cases of EWDA could be classified into gastric phenotype (5 lesions) and intestinal phenotype (4 lesions). The former resembled gastric foveolar epithelium, mucous neck cells or pyloric glands, but their papillary structures were frequently elongated and the tumor cells and their nuclei were slightly larger and more hyperchromatic compared to normal epithelium. The latter resembled intestinal metaplasia with minimal nuclear atypia and irregular glands; two of these lesions demonstrated complete intestinal phenotype, while two demonstrated incomplete intestinal phenotype. Ki-67 labeling index was low and none of the cases revealed over-expression of p53 and c-erbB-2 protein. CONCLUSION: Unlike minimal deviation carcinoma of the cervix, these findings suggest that EWDA of the stomach is a lesion of low-grade malignancy. This favorable biological behavior is supported by the data of a low Ki-67 labeling index and a lack of p53 or c-erbB-2 protein over-expression. Because of its resemblance to normal gastric mucosa or mucosa with intestinal metaplasia, EWDA is often misdiagnosed. To prevent the misdiagnosis of such lesions, the clinical and pathologic characteristics should be taken into consideration.

Adenocarcinoma↗

PubMed2006

Quantitative analysis of human telomerase reverse transcriptase in pancreatic cancer.

Although telomerase activity is a promising diagnostic marker, clinical introduction of this marker for cancer diagnosis is still problematic due to the lack of means of evaluating sample quality. Human telomerase reverse transcriptase (hTERT), one of the subunits of telomerase, is also a promising diagnostic marker. In the present study, we did large-scale analysis of 88 pancreatic juice samples to determine the feasibility of quantitative analysis of hTERT mRNA for diagnosis of pancreatic cancer. We found significant differences in hTERT expression among carcinoma-derived, intraductal papillary mucinous neoplasm (IPMN)-derived, and chronic pancreatitis-derived juice samples. Results showed that quantitative analyses of hTERT mRNAs are more useful in discriminating carcinoma from IPMN than from chronic pancreatitis. When the specificity was set at 100%, the sensitivity for differentiation between carcinoma and IPMN was 43.5%, whereas the sensitivity of cytologic examination was 22.0%. There were significant differences in hTERT expression among carcinoma cells, IPMN cells, and normal ductal cells isolated from pancreatic tissues by microdissection. Lymphocytes and hyperplastic epithelial cells isolated from tissues with the histologic appearance of pancreatitis showed various expression levels of hTERT. Our results suggest that quantitative analysis of hTERT mRNA in pancreatic juice is advantageous over cytologic analysis for differentiation between carcinoma and IPMN but probably not for differentiation between carcinoma and chronic pancreatitis.

DNA-Binding Proteins↗

PubMed2006

Adult case of an omphalomesenteric cyst resected by laparoscopic-assisted surgery.

This report describes an extremely rare adult case of an omphalomesenteric cyst resected by laparoscopic-assisted surgery. A 29-years-old Japanese man was referred and admitted to Kyushu University Hospital because of an abdominal mass and an elevated serum CEA (carcinoembryonic antigen) level (21.3 ng/mL) in August 2001. Abdominal CT and US demonstrated a cystic mass with septum and calcification. Laparoscopy showed a large mass to be attached to his abdominal wall, measuring 110 mm x 70 mm x 50 mm and filled with mucus. The mass was resected by laparoscopic-assisted surgery. The histological findings of its wall showed fibromuscular tissue, adipose tissue, calcification, and an intestinal structure. It was finally diagnosed to be an omphalomesenteric cyst.

Adult↗

PubMed2006

Quantitative analysis of MUC1 and MUC5AC mRNA in pancreatic juice for preoperative diagnosis of pancreatic cancer.

Pancreatic juice is a promising type of diagnostic sample for pancreatic cancer, and members of the mucin (MUC) family are diagnostic candidates. To evaluate the utility of MUC family members as diagnostic markers, we measured MUC mRNA expression in pancreatic tissues and pancreatic juice obtained from patients with different pancreatic diseases as well as in pancreatic cancer cell lines by real-time PCR. Furthermore, to support the possibility of early diagnosis by quantification of MUC1 and MUC5AC, immunohistochemistry and microdissection-based quantitative analysis of mRNA were carried out. There was no significant correlation between MUC1 and MUC5AC expression in cell lines. When beta-actin was used as a reference gene, median MUC1 and MUC5AC mRNA expression levels were remarkably greater in tumoral tissues than in non-tumoral tissues, but median MUC4 and MUC6 mRNA expression levels were not. Receiver operating characteristic curve analysis showed that quantitative analysis of MUC1 and MUC5AC mRNA in pancreatic juice is better diagnostic modality than that of MUC4 and MUC6 mRNA. Immunohistochemistry showed that MUC1 and MUC5AC were highly expressed in invasive ductal carcinomas (IDC) and moderately expressed in high-grade pancreatic intraepithelial neoplasia (PanIN); no staining was observed in normal ducts. Analysis of cells isolated by microdissection showed stepwise upregulation of MUC1 and MUC5AC in the development of high-grade PanIN to IDC. Our results suggest that MUC1 and MUC5AC are upregulated stepwise in pancreatic carcinogenesis and that quantitative assessment of MUC1 and MUC5AC mRNA in pancreatic juice has high potential for preoperative diagnosis of pancreatic cancer.

Biomarkers, Tumor↗

PubMed2006

The possible role of EWS-Fli1 in evasion of senescence in Ewing family tumors.

The chromosomal translocation t(11;22) yields the EWS-Fli1 fusion gene and is associated with oncogenesis of Ewing family tumors (EFT). In this study, using the RNA interference method, we show that EWS-Fli1-targeting small interfering RNAs (siRNA) depleted EWS-Fli1 protein and caused growth inhibition in EFT cells with the accumulation of p27 protein and the down-regulation of Skp2 protein in dose-dependent, time-dependent, and sequence-specific manners. Depletion of EWS-Fli1 subacutely elicited a senescence-like phenotype, but not apoptosis, in EFT cells. Furthermore, not only the knockdown of p27, but also the forced expression of Skp2, reduced the expression levels of p27 protein and partially rescued senescence-like phenotype caused by EWS-Fli1-targeting siRNAs. The accumulation of p27 protein in EWS-Fli1-depleted cells inhibited cdk2 kinase activity and was related to the stability of p27 protein, which resulted from a decrease in Skp2 protein. Immunohistochemical analysis of p27 and Skp2 proteins in EFT samples revealed that there was an inverse relationship between the expression profiles of p27 and Skp2 proteins. These findings indicate an important role of EWS-Fli1 in the prevention of senescence, leading to the unlimited growth and oncogenesis of EFT cells through a decrease in the stability of p27 protein due to increased action of Skp2-mediated 26S proteasome degradation.

Apoptosis↗

PubMed2006

Involvement of P-glycoprotein and MRP1 in resistance to cyclic tetrapeptide subfamily of histone deacetylase inhibitors in the drug-resistant osteosarcoma and Ewing's sarcoma cells.

Despite recent improvements in multimodal therapies for osteosarcoma (OS) and Ewing's family of tumors (EFTs), the prognosis of relapsed cases remains very poor because of the resistance to chemotherapy. Histone deacetylase inhibitors (HDACIs), including members of the cyclic tetrapeptide family such as FK228 and apicidin, are novel antitumor agents that can induce cell cycle arrest and apoptosis in various cancer cells. HDACIs also exhibit potent antitumor effects on OS and EFTs. However, to date there have been no studies to our knowledge reporting the effects of HDACIs on drug-resistant OS and EFTs. Here, we demonstrated that FK228 and apicidin exhibited strong resistance in doxorubicin-resistant clones of OS and EFTs expressing P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) and that P-gp and MRP1 might play a crucial role in the resistance mechanism to FK228 and apicidin. A P-gp inhibitor (verapamil) and an MRP1 inhibitor (MK571) could independently reverse the resistance to FK228 and apicidin in the drug-resistant clones. Moreover, the combination of verapamil and MK571 could enhance HDACI-induced cell number reduction in drug-resistant clones to a similar extent as that in their parental clones. Although these findings suggest the difficulty in treating drug-resistant tumors expressing P-gp and/or MRP1 with these HDACIs, the combination of P-gp and MRP1 inhibitors might reverse the resistance to the HDACIs in the treatment of those tumors. Because HDACIs are potent and promising antitumor drugs and seem to be close to clinical use, it is necessary to pay attention to the resistance mechanisms against HDACIs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗