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Tokushima-shi, Japan

Matsuo T.,Tokushima University | Komatsu M.,Tokushima University | Yoshimaru T.,Tokushima University | Kiyotani K.,Tokushima University | And 3 more authors.
International Journal of Oncology | Year: 2014

A number of glycosyltransferases have been identified and biologically characterized in cancer cells, yet their exact pathophysiological functions are largely unknown. Here, we report the critical role of β1,3-N- acetylgalactosaminyltransferase II (B3GALNT2), which transfers N-acetylgalactosamine (GalNAc) in a β1,3 linkage to N-acetylglucosamine, in the growth of breast cancer cells. Comprehensive transcriptomics, quantitative PCR and northern blot analyses indicated this molecule to be exclusively upregulated in the majority of breast cancers. Knockdown of B3GALNT2 expression by small interfering RNA attenuated cell growth and induced apoptosis in breast cancer cells. Overexpression of B3GALNT2 in HEK293T cells prompted secretion of the gene product into the culture medium, suggesting that B3GALNT2 is potentially a secreted protein. Furthermore, we demonstrated that B3GALNT2 is N-glycosylated on both Asn-116 and Asn-174 and that this modification is necessary for its secretion in breast cancer cells. Our findings suggest that this molecule represents a promising candidate for the development of a novel therapeutic targeting drug and a potential diagnostic tumor marker for patients with breast cancer, especially TNBC. Source

Yoshimaru T.,Tokushima University | Komatsu M.,Tokushima University | Tashiro E.,Keio University | Imoto M.,Keio University | And 5 more authors.
Scientific Reports | Year: 2014

Xanthohumol (XN) is a natural anticancer compound that inhibits the proliferation of oestrogen receptor-α (ERα)-positive breast cancer cells. However, the precise mechanism of the antitumour effects of XN on oestrogen (E2)-dependent cell growth, and especially its direct target molecule(s), remain(s) largely unknown. Here, we focus on whether XN directly binds to the tumour suppressor protein prohibitin 2 (PHB2), forming a novel natural antitumour compound targeting the BIG3-PHB2 complex and acting as a pivotal modulator of E2/ERα signalling in breast cancer cells. XN treatment effectively prevented the BIG3-PHB2 interaction, thereby releasing PHB2 to directly bind to both nuclear- and cytoplasmic ERα. This event led to the complete suppression of the E2-signalling pathways and ERα-positive breast cancer cell growth both in vitro and in vivo, but did not suppress the growth of normal mammary epithelial cells. Our findings suggest that XN may be a promising natural compound to suppress the growth of luminal-type breast cancer. © 2014, Nature Publishing Group. All rights reserved. Source

Komatsu M.,Tokushima University | Yoshimaru T.,Tokushima University | Matsuo T.,Tokushima University | Kiyotani K.,Tokushima University | And 11 more authors.
International Journal of Oncology | Year: 2013

Triple negative breast cancer (TNBC) has a poor outcome due to the lack of beneficial therapeutic targets. To clarify the molecular mechanisms involved in the carcinogenesis of TNBC and to identify target molecules for novel anticancer drugs, we analyzed the gene expression profiles of 30 TNBCs as well as 13 normal epithelial ductal cells that were purified by laser-microbeam microdissection. We identified 301 and 321 transcripts that were significantly upregulated and downregulated in TNBC, respectively. In particular, gene expression profile analyses of normal human vital organs allowed us to identify 104 cancer-specific genes, including those involved in breast carcinogenesis such as NEK2, PBK and MELK. Moreover, gene annotation enrichment analysis revealed prominent gene subsets involved in the cell cycle, especially mitosis. Therefore, we focused on cell cycle regulators, asp (abnormal spindle) homolog, microcephaly-associated (Drosophila) (ASPM) and centromere protein K (CENPK) as novel therapeutic targets for TNBC. Small-interfering RNA-mediated knockdown of their expression significantly attenuated TNBC cell viability due to G1 and G2/M cell cycle arrest. Our data will provide a better understanding of the carcinogenesis of TNBC and could contribute to the development of molecular targets as a treatment for TNBC patients. Source

Srinivasan Y.,Tokyo Medical University | Sasa M.,Tokushima Breast Care Clinic | Honda J.,National Higashi Tokushima Hospital | Takahashi A.,RIKEN | And 5 more authors.
Pharmacogenetics and Genomics | Year: 2011

Objectives: Despite long-term clinical experience with epirubicin, unpredictable severe adverse reactions remain an important determinant to limit the drug use. To identify a genetic factor(s) affecting the risk of epirubicin-induced leukopenia/neutropenia, we performed a genome-wide association study. Methods: We studied 270 patients consisting of 67 patients with grade 3 or 4 leukopenia/neutropenia, and 203 patients showing no toxicity (patients with grade 1 or 2 were excluded from the study) for genome-wide association study. We further examined the single nucleotide polymorphisms (SNPs) showing P values of less than 0.0001 using an additional set of 48 patients with grade 3/4 leukopenia/neutropenia. Results: The combined analysis indicated that rs2916733 in microcephalin 1 [combined PFisher min=2.27×10 -9, odds ratio (OR)=2.74 with 95% confidence interval (CI)=1.96-3.83; the nonrisk genotype as reference] was significantly associated with epirubicin-induced leukopenia/neutropenia. A subgroup analysis of patients with only breast cancer showed a similar trend of association for the marker SNP rs2916733 (combined PFisher min=6.76×10 -7, OR=2.80 with 95% CI=1.86-4.21). We subsequently performed haplotype analysis and found that a haplotype constructed from rs2916733 and rs1031309, which was in linkage disequilibrium with rs2916733 (r 2=0.64), showed stronger association (P=2.20×10 -10, OR=2.88 with 95% CI=2.05-4.03) than a single landmark SNP (rs2916733; P=2.27×10 -9, OR=2.74 with 95% CI=1.96-3.83), suggesting that causative variant(s) that could influence the susceptibility of epirubicin-induced adverse drug reactions (ADRs) might exist in this haplotype. Conclusion: Our findings show that genetic variants in the microcephalin 1 locus are suggestively associated with the risk of epirubicin-induced ADRs and might be applicable in development of diagnostic system for predicting the risk of the ADRs, leading to better prognosis and quality of life for patients with cancer. However, these results should be considered preliminary until replicated in adequately larger powered and controlled samples. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source

Yoshimaru T.,Tokushima University | Komatsu M.,Tokushima University | Miyoshi Y.,Hyogo College of Medicine | Honda J.,National Hospital Organization Higashitokushima Medical Center | And 2 more authors.
Cancer Science | Year: 2015

Our previous studies demonstrated that specific inhibition of the BIG3-PHB2 complex, which is a critical modulator in estrogen (E2) signaling, using ERAP, a dominant negative peptide inhibitor, leads to suppression of E2-dependent estrogen receptor (ER) alpha activation through the reactivation of the tumor suppressive activity of PHB2. Here, we report that ERAP has significant suppressive effects against synergistic activation caused by the crosstalk between E2 and growth factors associated with intrinsic or acquired resistance to anti-estrogen tamoxifen in breast cancer cells. Intrinsic PHB2 released from BIG3 by ERAP effectively disrupted each interaction of membrane-associated ERα and insulin-like growth factor 1 receptor beta (IGF-1Rβ), EGFR, PI3K or human epidermal growth factor 2 (HER2) in the presence of E2 and the growth factors IGF or EGF, followed by inhibited the activation of IGF-1Rβ, EGFR or HER2, and reduced Akt, MAPK and ERα phosphorylation levels, resulting in significant suppression of proliferation of ERα-positive breast cancer cells in vitro and in vivo. More importantly, combined treatment with ERAP and tamoxifen led to a synergistic suppression of signaling that was activated by crosstalk between E2 and growth factors or HER2 amplification. Taken together, our findings suggest that the specific inhibition of BIG3-PHB2 is a novel potential therapeutic approach for the treatment of tamoxifen-resistant breast cancers activated by the crosstalk between E2 and growth factor signaling, especially in premenopausal women. © 2015 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association. Source

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