Papers - TAZAKI Akira

Erythropoietin regulates tumour growth of human malignancies Reviewed

Y Yasuda, Y Fujita, T Matsuo, S Koinuma, S Hara, A Tazaki, M Onozaki, M Hashimoto, T Musha, K Ogawa, H Fujita, Y Nakamura, H Shiozaki, H Utsumi

CARCINOGENESIS   Vol. 24 ( 6 ) page： 1021 - 9   2003.6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

In addition to the chief function of erythropoietin (Epo) in promoting erythropoiesis, some other roles have been found in the brain and uterus. We have reported that signalling pathways of Epo and Epo receptor (EpoR) are involved in the tumourigenesis of ovarian and uterine cancers. To determine whether Epo plays a similar role in other malignancies, we studied the expression of Epo in several malignant human cell lines. We found that 24 malignant human cell lines examined express Epo and EpoR regardless of their origins, types, genetic characteristics and biological properties and secrete a very small amount of Epo individually and that most of them respond to hypoxic stimuli by enhanced secretion of Epo. To determine whether the Epo-EpoR pathway operates in tumours of these cell lines, we transplanted several cell lines into nude mice and confirmed the presence of Epo-responsive sites in xenografts in which the phosphorylation of the STAT5 (signal transducer and activator of transcription) is detectable. Furthermore, in nude mice we blocked the Epo signalling in xenografts of two representative cell lines, stomach choriocarcinoma and melanoma, by i.p. injections of EpoR antagonist and found inhibition of angiogenesis and survival of tumour cells leading to destruction of tumour masses and disturbances of phosphorylation of STAT5. In contrast, Epo mimetic peptide promotes angiogenesis and tumour cell survival. These findings suggest that Epo is indispensable for the growth and viability of malignant tumour and also that the deprivation of Epo signalling may be a promising therapy for human malignancy.

DOI： 10.1093/carcin/bgg060

Web of Science

PubMed

The body margin of the planarian Dugesia japonica: characterization by the expression of an intermediate filament gene Reviewed

A Tazaki, K Kato, H Orii, K Agata, K Watanabe

DEVELOPMENT GENES AND EVOLUTION   Vol. 212 ( 8 ) page： 365 - 73   2002.9

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER-VERLAG  

We have cloned and sequenced a cDNA encoding an intermediate filament protein (IF) from the planarian Dugesia japonica named DjIFb. The deduced amino acid sequence of DjIFb has similarity to those of protostomic IFs and lamins, supporting a previous hypothesis that the protostomic IFs, including DjIFb, are evolutionarily closer to lamins than to vertebrate cytoplasmic IFs. In addition, analysis of the exon/intron organization revealed that 8 out of 10 introns of DjIFb were coincident in their position, even in the codon phase, with those of the non-neuronal IF of the snail Helix aspersa. This suggests that the Platyhelminthes are not the most primitive Bilateria but instead are evolutionarily close to the Mollusca. The DjIFb gene was expressed in particular cells, probably a kind of adhesive gland cell, which were present in the marginal region encircling the planarian body. The localization of DjIFb protein suggests that it plays an important role in the secretion of an adhesive substance. The specific expression pattern of the DjIFb gene enabled us to monitor how the body margin forms during planarian regeneration.

DOI： 10.1007/s00427-002-0253-0

Web of Science

PubMed

Neural network in planarian revealed by an antibody against planarian synaptotagmin homologue

A Tazaki, S Gaudieri, K Ikeo, T Gojobori, K Watanabe, K Agata

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS   Vol. 260 ( 2 ) page： 426 - 432   1999.7

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC  

In order to investigate the neural connection. of planarian, it is imperative to produce an antibody that specifically stains axons. To identify axon-specific genes, we constructed a cDNA library from a single eye by using a single cell PCR method, in which visual neurons are major components, and sequenced one thousand independent clones. We succeeded in the identification of a planarian homologue of synaptotagmin, Djsyt, whose specific expression in neurons was confirmed by in situ hybridization. The antibody against DjSYT specifically stained axons although its mRNA is distributed in the cell bodies. By using anti-DjSYT, we succeeded in the visualization of neural connections in planarians by whole mount staining. The anti-DjSYT antibody will become a powerful tool to analyze the molecular mechanisms underlying neural network formation in planarian. (C) 1999 Academic Press.

DOI： 10.1006/bbrc.1999.0933

Web of Science

Scopus

PubMed