Ken-ichi Katsube

The Nephroblastoma Overexpressed Gene (NOV/ccn3) Protein Associates with Notch1 Extracellular Domain and Inhibits Myoblast Differentiation via Notch Signaling Pathway

We demonstrate a novel interaction of the nephroblastoma overexpressed gene (NOV), a member of the CCN gene family, with the Notch signaling pathway. NOV associates with the epidermal growth factor-like repeats of Notch1 by the CT (C-terminal cysteine knot) domain. The promoters of HES1and HES5, which are the downstream transducers of Notch signaling, were activated by NOV. Expressions of NOV andNotch1 were concomitant in the presomitic mesoderm and later in the myocytes and chondrocytes, suggesting their synergistic effects in mesenchymal cell differentiation. In C2/4 myogenic cells, elevated expression of NOV led to down-regulation of MyoDand myogenin, resulting in inhibition of myotube formation. These results indicate that NOV-Notch1 association exerts a positive effect on Notch signaling and consequently suppresses myogenesis.

Loss of Syndecan‐1 and Increased Expression of Heparanase in Invasive Esophageal Carcinomas

Heparan sulfate proteoglycans play important biological roles in cell‐cell and cell‐matrix adhesion, and are closely associated with growth factor actions. Loss of syndecan‐1, a cell surface‐bound heparan sulfate proteoglycan, has been reported for advanced head and neck carcinomas, and expression of endoglycosidic heparanase, which cleaves heparan sulfate glycosaminoglycans (HS‐GAGs), is associated with invasion and metastatic potential of malignant tumors. Paraffin sections of 103 primary esophageal squamous cell carcinomas were immunohistochemically examined for the expression of syndecan‐1 core protein, HS‐GAGs and heparanase protein, and the results were compared with various clinicopathological parameters, such as invasion depth. For 16 cases, fresh tumor samples were quantitatively analyzed for heparanase and syndecan‐1 mRNA expression by real‐time RT‐PCR in addition to the immunohistochemical studies. Syndecan‐1 core protein and HS‐GAGs expression was significantly decreased in pT2 and pT3 cases compared with their pTis and pTl counterparts. Decreased expression of core protein and HS‐GAGs was correlated with the incidence of lymphatic invasion, and venous involvement. Furthermore, decreased expression of HS‐GAGs was correlated positively with the incidence of nodal metastasis and distant organ metastasis, and negatively with the grade of tumor cell differentiation. The percentage of cytoplas‐mic heparanase protein‐positive cases increased significantly in pT2 and pT3 cases compared to that in pTis and pTl cases, and this was associated with lymphatic invasion, and venous and lymph nodal involvement. The level of heparanase mRNA was inversely correlated with the degree of HS‐GAGs expression rather than core protein. In conclusion, loss of syndecan‐1 and heparanase overexpression in esophageal squamous cell carcinomas are closely associated with malignant potential. Regarding the mechanism of loss of HS‐GAGs, heparanase upregulation appears to play an important role.

Role of CCN, a vertebrate specific gene family, in development

The CCN family of genes constitutes six members of small secreted cysteine rich proteins, which exists only in vertebrates. The major members of CCN are CCN1 (Cyr61), CCN2 (CTGF), and CCN3 (Nov). CCN4, CCN5, and CCN6 were formerly reported to be in the Wisp family, but they are now integrated into CCN due to the resemblance of their four principal modules: insulin like growth factor binding protein, von Willebrand factor type C, thrombospondin type 1, and carboxy‐terminal domain. CCNs show a wide and highly variable expression pattern in adult and in embryonic tissues, but most studies have focused on their principal role in osteo/chondrogenesis and vasculo/angiogenesis from the aspect of migration, growth, and differentiation of mesenchymal cells. CCN proteins simultaneously integrate and modulate the signals of integrins, bone morphogenetic protein, vascular endothelial growth factor, Wnt, and Notch by direct binding. However, the priority in the use of the signals is different depending on the cell status. Even the equivalent counterparts show a difference in signal usage among species. It may be that the evolution of the CCN family continues to keep pace with vertebrate evolution itself.

Increased RANKL expression is related to tumour migration and metastasis of renal cell carcinomas

Receptor activator of NF‐κB ligand (RANKL) and its receptor, receptor activator of NF‐κB (RANK), play a key role in osteoclastogenesis, and osteoprotegerin (OPG) acts as a decoy receptor for RANKL. We investigated the role of the RANKL–RANK–OPG system in renal cell carcinomas (RCCs), which frequently metastasize to bones. Real‐time quantitative PCR revealed that RANKL mRNA expression was higher in clear cell RCCs than in papillary and chromophobe RCCs. Similarly, RANKL protein expression level in clear cell RCCs was higher than that in papillary and chromophobe RCCs, showing positive correlations with the primary tumour stage and distant metastasis. There was no significant association between the expression level of RANK, OPG and histological subtypes of RCC. RANKL and RANK expression was observed in metastatic RCCs in the bone and other organs, suggesting that they play a role in metastasis to the bone and other organs. Recombinant RANKL protein stimulated migration of a clear cell RCC cell line, Caki‐1, in vitro, and this enhanced migration was inhibited by the administration of recombinant OPG protein. Furthermore, multivariate Cox analysis revealed that elevated RANKL and RANK expression with low‐OPG expression was a significant and independent predictor of recurrence, bone metastasis and a poor prognosis. These data suggest that the RANKL–RANK–OPG system is involved not only in the bone metastasis of RCCs but also in metastasis to other organs through the stimulation of cancer cell migration. Copyright

Expression of Snail and Slug in renal cell carcinoma: E-cadherin repressor Snail is associated with cancer invasion and prognosis

The Snail family transcription factors have been proposed as important mediators of epithelial–mesenchymal transition because of their role in down-regulation of E-cadherin and up-regulation of matrix metalloproteinases (MMPs). The present study was undertaken to investigate the expression of Snail, Slug and their associations with cancer invasion and prognosis in renal cell carcinomas (RCCs). Ninety-seven primary RCCs were analyzed for the protein expression of Snail, Slug, MMP2 and MMP9 by immunohistochemistry. Snail protein expression level was positively correlated with pathological tumor stage, histological grade and the presence of sarcomatoid carcinoma. On the contrary, Slug protein expression level was negatively correlated with pathological tumor stage, suggesting that Slug was down-regulated in advanced RCCs. Because Snail was positively associated with malignant potential of RCCs, involvement of Snail in the invasiveness of an RCC cell line 786-O was examined in the Matrigel invasion assay by down-regulating the gene expression with small interfering RNA (siRNA). Targeting the Snail, not Slug, expression in 786-O cells with siRNA caused down-regulation of the gene expression of Snail, vimentin, MMP2 and MMP9, but up-regulated the E-cadherin. Invasion of the cells through Matrigel in vitro was inhibited under this condition. Furthermore, expression levels of MMP2 and MMP9 were positively correlated with pathological tumor stage and the presence of sarcomatoid carcinoma. Statistical analysis indicated that elevated Snail, MMP2 and MMP9 protein expression are significantly worse predictors of disease-free and disease-specific survival of the patients with RCC. In conclusion, these data suggest that Snail has an important role in invasion and metastasis, and that silencing the gene may be a potential therapeutic target in RCCs.

Down-regulation of keratin 4 and keratin 13 expression in oral squamous cell carcinoma and epithelial dysplasia: a clue for histopathogenesis

Sakamoto K, Aragaki T, Morita K‐i, Kawachi H, Kayamori K, Nakanishi S, Omura K, Miki Y, Okada N, Katsube K‐i, Takizawa T & Yamaguchi A
(2011) Histopathology58, 531–542
Down‐regulation of keratin 4 and keratin 13 expression in oral squamous cell carcinoma and epithelial dysplasia: a clue for histopathogenesis

Reduction of NOTCH1 expression pertains to maturation abnormalities of keratinocytes in squamous neoplasms

Notch is a transmembrane receptor functioning in the determination of cell fate. Abnormal Notch signaling promotes tumor development, showing either oncogenic or tumor suppressive activity. The uncertainty about the exact role of Notch signaling, partially, stems from inconsistencies in descriptions of Notch expression in human cancers. Here, we clarified basal-cell dominant expression of NOTCH1 in squamous epithelium. NOTCH1 was downregulated in squamous neoplasms of oral mucosa, esophagus and uterine cervix, compared with the normal basal cells, although the expression tended to be retained in cervical lesions. NOTCH1 downregulation was observed even in precancers, and there was little difference between cancers and high-grade precancerous lesions, suggesting its minor contribution to cancer-specific events such as invasion. In culture experiments, reduction of NOTCH1 expression resulted in downregulation of keratin 13 and keratin 15, and upregulation of keratin 17, and NOTCH1 knockdown cells formed a dysplastic stratified epithelium mimicking a precancerous lesion. The NOTCH1 downregulation and the concomitant alterations of those keratin expressions were confirmed in the squamous neoplasms both by immunohistochemical and cDNA microarray analyses. Our data indicate that reduction of NOTCH1 expression directs the basal cells to cease terminal differentiation and to form an immature epithelium, thereby playing a major role in the histopathogenesis of epithelial dysplasia. Furthermore, downregulation of NOTCH1 expression seems to be an inherent mechanism for switching the epithelium from a normal and mature state to an activated and immature state, suggesting its essential role in maintaining the epithelial integrity.

Inhibitory effect of CT domain of CCN3/NOV on proliferation and differentiation of osteogenic mesenchymal stem cells, Kusa-A1

CCN3/NOV activates the Notch signal through the carboxyl terminal cysteine-rich (CT) domain. CCN3 transfection to Kusa-A1 inhibited osteogenic differentiation and cell proliferation, which is accompanied by upregulation of Hes/Hey, Notch downstream targets, and p21, a CDK inhibitor. Upregulation of Hes/Hey and p21 was abrogated by the deletion of CT domain. Anti-proliferative activity of CCN3 was also abrogated by CT domain deletion whereas anti-osteogenic activity was not completely abrogated. We found that CT domain-deleted CCN3 still possesses antagonistic effect on BMP-2. These results suggest that CCN3 employs Notch and BMP pathways in anti-osteogenic activity while it inhibits cell proliferation uniquely by Notch/p21 pathway.

Ectopic expression of lunatic Fringe leads to downregulation of Serrate‐1 in the developing chick neural tube; analysis using in ovo electroporation transfection technique

Lunatic Fringe (l‐Fng) is one of the vertebrate homologues of Drosophila Fringe, which interacts with the Notch signal pathway and regulates activation of the Notch ligands, Delta and Serrate. To elucidate the roles of l‐Fng in vertebrate neurogenesis, we transfected chick l‐Fng (C‐l‐Fng) to chick neural tube using the in ovo electroporation technique and examined the subsequent changes in expression of Notch‐related genes. We observed downregulation of C‐Serrate‐1 by ectopic C‐l‐Fng expression which implied that C‐l‐Fng acts on the vertebrate Notch pathway to regulate the expression of its ligand.

Periostin Associates with Notch1 Precursor to Maintain Notch1 Expression under a Stress Condition in Mouse Cells

Background Matricellular proteins, including periostin, modulate cell-matrix interactions and cell functions by acting outside of cells. Methods and Findings In this study, however, we reported that periostin physically associates with the Notch1 precursor at its EGF repeats in the inside of cells. Moreover, by using the periodontal ligament of molar from periostin-deficient adult mice (Pn−/− molar PDL), which is a constitutively mechanically stressed tissue, we found that periostin maintained the site-1 cleaved 120-kDa transmembrane domain of Notch1 (N1™) level without regulating Notch1 mRNA expression. N1™ maintenance in vitro was also observed under such a stress condition as heat and H2O2 treatment in periostin overexpressed cells. Furthermore, we found that the expression of a downstream effector of Notch signaling, Bcl-xL was decreased in the Pn−/− molar PDL, and in the molar movement, cell death was enhanced in the pressure side of Pn−/− molar PDL. Conclusion These results suggest the possibility that periostin inhibits cell death through up-regulation of Bcl-xL expression by maintaining the Notch1 protein level under the stress condition, which is caused by its physical association with the Notch1 precursor.