Tamotsu Takeuchi

Expression of T-cadherin (CDH13, H-cadherin) in human brain and its characteristics as a negative growth regulator of epidermal growth factor in neuroblastoma cells

Abstract: In the present study, we first examined the expression of T‐cadherin in human CNS by northern blot analysis, immunohistochemical staining, and in situ hybridization. Northern blot analysis demonstrated expression of T‐cadherin in human adult cerebral cortex, medulla, thalamus, and midbrain. Immunohistochemical staining with a newly generated monoclonal antibody, designated MA‐511, revealed strong expression of T‐cadherin in neural cell surface membrane and neurites in adult cerebral cortex, medulla oblongata, and nucleus olivaris. Little or no expression of T‐cadherin was found in spinal cord. We further examined T‐cadherin expression in various developing nervous systems, and found that T‐cadherin expression was lower in developing brain than in adult brain. In situ hybridization revealed that neural cells in medulla oblongata and nucleus olivaris, but not in spinal cord, possessed T‐cadherin molecules. We transfected T‐cadherin‐negative TGW and NH‐12 neuroblastoma cells with a T‐cadherin cDNA‐containing expression vector. T‐cadherin‐expressing neuroblastoma cells lost mitogenic proliferative response to epidermal growth factor. Epidermal growth factor is known to be required for proliferation of neural stem cells. This finding, together with those of the present study, suggests that T‐cadherin functions as a negative regulator of neural cell growth.

Adiponectin receptors, with special focus on the role of the third receptor, T-cadherin, in vascular disease

There is increasing acknowledgment of the public health burden of metabolic syndrome. The metabolic syndrome is defined as emerging cardiovascular risk factors, or atherosclerosis, that are related to underlying insulin resistance. One of the adipokines, adiponectin, has antiatherogenic effects and augments the metabolic effects of insulin. To reduce mortality from cardiovascular disease, it is important to understand the pathophysiological properties of adiponectin and receptors in atherosclerotic regions. Recently, T-cadherin, which has been recognized as a unique cadherin molecule, has been characterized as a novel adiponectin receptor on vascular endothelial cells and smooth muscle. Notably, T-cadherin (also known as CDH13, cadherin 13, and H-cadherin) is abundantly expressed in injured vascular endothelial and smooth muscle cells in atherosclerotic regions. In the present review, we describe recent progress in research on adiponectin receptors, with emphasis on the unique vascular adiponectin receptor, T-cadherin, and its role in vascular disease.

HIV-1 Protease Inhibitor, Ritonavir: A Potent Inhibitor of CYP3A4, Enhanced the Anticancer Effects of Docetaxel in Androgen-Independent Prostate Cancer Cells In vitro and In vivo

We previously showed that HIV-1 protease inhibitors (PIs) slowed the proliferation of human myeloid leukemia cells and enhanced their differentiation in the presence of all–trans-retinoic acid. In this study, we found that PIs, including ritonavir, saquinavir, and indinavir, inhibited the growth of DU145 and PC-3 androgen-independent prostate cancer cells as measured by a clonal proliferation assay. Recent studies showed that ritonavir inhibited cytochrome P450 3A4 enzyme (CYP3A4) in liver microsomes. The CYP3A4 is involved in drug metabolism and acquisition of drug resistance. To clarify the drug interaction between ritonavir and other anticancer drugs, we cultured DU145 cells with docetaxel either alone or in combination with ritonavir. Ritonavir enhanced the antiproliferative and proapoptotic effects of docetaxel in the hormonally independent DU145 prostate cancer cells in vitro as measured by the clonogenic soft agar assay and detection of the activated form of caspase-3 and cleavage of poly(ADP-ribose) polymerase using Western blot analysis. Real-time PCR showed that docetaxel induced the expression of CYP3A4 at the transcriptional level, and ritonavir (10−5 mol/L) completely blocked this induction. An ELISA-based assay also showed that ritonavir inhibited DNA binding activity of nuclear factor κB (NFκB) in DU145 cells, which is a contributor to drug resistance in cancer cells. Furthermore, combination treatment of docetaxel and ritonavir dramatically inhibited the growth of DU145 cells present as tumor xenografts in BNX nude mice compared with either drug alone. Importantly, docetaxel induced expression of CYP3A4 in DU145 xenografts, and ritonavir completely blocked this induction. Ritonavir also inhibited NFκB DNA binding activity in DU145 xenografts. Extensive histologic analyses of the liver, spleen, kidneys, bone marrow, skin, and subcutaneous fat pads from these mice showed no abnormalities. In summary, combination therapy of ritonavir and anticancer drugs holds promise for the treatment of individuals with advanced, drug resistant cancers.

HIV‐1 protease inhibitor induces growth arrest and apoptosis of human prostate cancer LNCaP cells in vitro and in vivo in conjunction with blockade of androgen receptor STAT3 and AKT signaling

This study found that the HIV‐1 protease inhibitor nelfinavir (NFV) induced growth arrest and apoptosis of human prostate cancer cells (LNCaP, DU145 and PC‐3 cells), as measured by MTT and terminal deoxyribonucleotide transferase‐mediated dUTP nick end labeling (TUNEL) assays, respectively, on the third day of culture. In addition, NFV blocked androgen receptor (AR) signaling in association with downregulation of nuclear levels of AR in LNCaP cells as measured by reporter assay and western blot analysis. As expected, NFV downregulated the level of the AR target molecule prostate specific antigen in these cells. Moreover, NFV disrupted STAT3 signaling; protease inhibitors blocked interleukin‐6‐induced phosphorylation of STAT3 and inhibited STAT3 DNA binding activity in LNCaP and DU145 cells, as measured by western blot analysis and enzyme‐linked immunosorbent assay (ELISA), respectively. Furthermore, NFV blocked AKT signaling in prostate cancer cells as measured by kinase assay with glycogen synthase kinase‐3α/β as a substrate. Importantly, NFV inhibited the proliferation of LNCaP cells presented as tumor xenografts in BALB/c nude mice without side‐effects. Taken together, NFV inhibited the proliferation of prostate cancer cells in conjunction with blockade of signaling by AR, STAT3, and AKT, suggesting that this family of compounds might be useful for the treatment of individuals with prostate cancer. (Cancer Sci 2005; 96: 425 – 433)

Loss of T-cadherin (CDH13, H-cadherin) expression in cutaneous squamous cell carcinoma.

We previously reported that T-cadherin (CDH13, H-cadherin), a unique cadherin molecule, was expressed on the basal cell layer in normal murine and human epidermis. In the present study, T-cadherin expression in archival human skin specimens comprising a spectrum of human squamous cell neoplasia was investigated. T-cadherin expression was observed in both normal epidermal basal cells and adnexal epithelial cells of formalin-fixed and paraffin-embedded tissue sections. Western immunoblotting also revealed that mature T-cadherin protein was expressed in cultured human skin tissue equivalent. Atypical keratinocytes in 27 of 53 specimens of actinic keratosis and 23 of 30 specimens of Bowen’s disease expressed T-cadherin. In contrast, T-cadherin was focally expressed in 6 of 56 invasive cutaneous squamous cell carcinomas. To explore the molecular mechanism of down-regulation of T-cadherin expression in invasive squamous cell carcinoma, loss of heterozygosity, genetic alternations, and methylation status in the 5′ region of the T-cadherin gene were investigated. Loss of heterozygosity at intron 1 of the T-cadherin gene was observed in 8 of 28 informative cases of invasive squamous cell carcinoma. Although no structural genomic alternations were found by sequence analysis, aberrant promoter methylation of the T-cadherin gene was found in 12 of 28 invasive squamous cell carcinomas. T-cadherin expression was restored in cultured A431 cells, in which aberrant methylation was found by treatment with the demethylating agent 5′-aza-2-deoxycytidine. These findings suggest that a combination of deletion and aberrant methylation of the T-cadherin gene may play a role in loss of gene expression in a considerable number of invasive cutaneous squamous cell carcinomas.

Sun-exposure- and aging-dependent p53 protein accumulation results in growth advantage for tumour cells in carcinogenesis of nonmelanocytic skin cancer

Abstract Three hundred and sixteen patients with nonmelanocytic skin cancer, including 46 cases of Bowen’s disease (BOD), 134 cases of squamous cell carcinoma (SCC), and 136 cases of basal cell carcinoma (BCC), were examined immunohistochemically using monoclonal antibody DO-7 to assess p53 protein accumulation related to sun exposure and ageing, and growth and differentiation of skin cancer and its precursors. The rates of p53 immunostaining of BOD, SCC and BCC were 80.4%, 76.1% and 70.6%, respectively. p53-positive cells were present not only in cancer nests, but also in dysplastic and even morphologically normal epidermis adjoining cancers. Sun exposure was statistically correlated with the p53 immunostaining scores in morphologically normal epidermis of the three skin cancers and in cancer nests of SCC and BCC. The positivity and score of p53 protein often differed significantly among the three types of cancer, especially in regions of dysplasia. Interestingly, differentiation of SCC was correlated with individual p53 scores for dysplasia and cancer nests, especially for dysplasia. BOD, as the precursor of SCC, demonstrated the strongest p53 expression. Furthermore, 12.3% cases with p53 negative cancer nests showed p53-positive reaction in dysplasia and in morphologically normal epidermis. It seems that the accumulation of p53 protein plays a part in precancerous lesions and in the genesis of more highly differentiated types of skin cancer and affects mainly the growth of tumour cells rather than their differentiation. For BCC, however, age was significantly related to p53 expression. Our findings suggest that overexpression of p53 in normal skin and cancer nests of SCC and BCC is significantly related to sun exposure, that the expression of p53 in BCC is an age-dependent process, and that the early accumulation of p53 protein may be a useful predictor for the detection of nonmelanocytic skin cancer.

Developmental expression of carbonic anhydrase-related proteins VIII, X, and XI in the human brain

Three cDNA homologues of carbonic anhydrase with unknown biological functions have been reported: carbonic anhydrase-related proteins (CA-RP) VIII, X, and XI. In the present study, we produced monoclonal antibodies to these CA-RPs and studied their regional and cellular distributions in the human adult and fetal brains by immunohistochemical analysis. In the adult brain, CA-RP VIII was expressed in the neural cell body spreading to most parts of the brain. CA-RP X was expressed in the myelin sheath and its expression was shown in the cytoplasm of cultured tumor cells by immunocytochemical analysis. CA-RP XI was expressed in the neural cell body, neurites, and astrocytes in relatively limited regions of the brain. In the fetal brain, CA-RP VIII and XI were expressed in the neuroprogenitor cells in the subventricular zone as early as the 84th day of gestation and subsequently detected in the neural cells migrating to the cortex. CA-RP X first appeared in the neural cells in the cortex at the 141st day. In the choroid plexus, the epithelial cells gave CA-RP VIII and XI expressions in both adult and fetal brains. From the findings in the present study on the distribution and the developmental expression of CA-RP VIII, X, and XI in the human brain we suggest that these CA-RPs play roles in various biological process of the CNS.

Skeletrophin, a novel ubiquitin ligase to the intracellular region of Jagged-2, is aberrantly expressed in multiple myeloma.

Recent research has indicated that ligand-dependent activation of the Notch receptor in stromal cells plays a crucial role in the tumorigenesis of multiple myeloma. Ubiquitination of intracellular regions of Notch receptor and its ligands is important for Notch signal transduction. In vitro autoubiquitination analysis using recombinant proteins identified skeletrophin as a novel RING finger-dependent ubiquitin ligase. Skeletrophin bound the intracellular regions of the Notch ligand Jagged-2, but not to those of Delta-1, -3, -4, or Jagged-1. Skeletrophin, but not its RING-mutated form, ubiquitinized the intracellular region of Jagged-2. In malignant plasma cells from 23 of 40 multiple myeloma specimens, strong skeletrophin expression was observed, especially from patients with osteolytic bone lesions. Cytoplasmic localization, which may indicate Jagged-2 internalization, was found in many skeletrophin-positive myeloma cells. In contrast, skeletrophin was only weakly expressed in a few nonneoplasmic plasma cells in chronically inflamed tissues. Interestingly, exogenous expression of skeletrophin, but not the RING-mutated form, in Jagged-2-positive P3U1 myeloma cells induced Hes-1 (Hairy and Enhancer of Split homolog-1) gene expression in Notch receptor-positive bone marrow stromal cells through direct cell-cell contact. Thus, skeletrophin is a novel ubiquitin ligase that targets the intracellular region of Jagged-2 and is aberrantly overexpressed in multiple myeloma cells, possibly activating Hes-1 on stromal cells through ligand-dependent Notch signaling.

An adiponectin receptor, T-cadherin, was selectively expressed in intratumoral capillary endothelial cells in hepatocellular carcinoma: possible cross talk between T-cadherin and FGF-2 pathways

T-cadherin is a unique receptor of adiponectin, which plays a critical role in various angiogenesis. In the present study, T-cadherin expression in tumor vessels of hepatocellular carcinoma (HCC) and, subsequently, the molecular mechanism, which induced T-cadherin expression in sinusoidal endothelial cells were investigated. Sinusoidal endothelium in nontumorous liver, chronic hepatitis, or liver cirrhosis expressed little or no T-cadherin. By contrast, T-cadherin was found in intratumoral capillary endothelial cells of 34 out of 63 HCC specimens. In positive cases, focal T-cadherin expression was found in well-differentiated HCC, whereas diffuse and intense T-cadherin expression was observed in poorly differentiated HCC specimens. T-cadherin was much expressed in intratumoral capillary endothelial cells in a less differentiated HCC region than that in a well-differentiated region in five specimens, in which various differentiated HCC components were coexistent. In a double-cell chamber assay, fibroblast growth factor-2 appeared to have a critical role to induce T-cadherin in cultured liver sinusoidal endothelial cells. The present finding indicated that T-cadherin was selectively expressed in intratumoral capillary endothelial cells of many HCCs, increasingly expressed as tumor progression, and T-cadherin may have a positive role in angiogenesis of HCC. In addition, cross talk between the signal pathways mediated by fibroblast growth factor-2 and adiponectin was suggested.

Downregulation of expression of a novel cadherin molecule, T-cadherin, in basal cell carcinoma of the skin

T‐cadherin appears to act as a tumor‐suppressor factor in various cancers. Downregulation of T‐cadherin is caused by a combination of allelic loss and hypermethylation of the T‐cadherin promoter region and is related to cancer invasion. To elucidate the molecular mechanism of invasiveness of basal cell carcinoma of the skin, T‐cadherin expression was investigated in archival pathological tissue sections made up of normal counterparts of skin and various types of basal cell carcinoma. Immunohistochemical staining showed that T‐cadherin was not expressed in 38 of 51 (75%) basal cell carcinoma specimens, whereas normal counterparts of the skin appeared to express abundant T‐cadherin. Loss of heterozygosity in intron 1 of the T‐cadherin gene was found in four of 20 informative cases that did not express T‐cadherin. Aberrant methylation of the T‐cadherin promoter region also was found in six of 25 basal cell carcinomas by methylation‐specific polymerase chain reaction. In contrast, no structural alternations were found in two loss of heterozygosity–positive basal cell carcinomas on sequence analysis. These findings indicated that T‐cadherin expression was downregulated by a combination of allelic loss and aberrant methylation in basal cell carcinoma of the skin. Loss of T‐cadherin expression might be related to the biological behavior of basal cell carcinoma. In addition, results of the present study suggested that downregulation of T‐cadherin in various cancers might be related to tumor invasiveness rather than metastasis, because basal cell carcinoma of the skin principally lacks metastatic activity.