The acquisition of endocrine resistance is a common obstacle in endocrine therapy of patients with oestrogen receptor-α (ERα)-positive breast tumours. We previously demonstrated that the BIG3–PHB2 complex has a crucial role in the modulation of oestrogen/ERα signalling in breast cancer cells. Here we report a cell-permeable peptide inhibitor, called ERAP, that regulates multiple ERα-signalling pathways associated with tamoxifen resistance in breast cancer cells by inhibiting the interaction between BIG3 and PHB2. Intrinsic PHB2 released from BIG3 by ERAP directly binds to both nuclear- and membrane-associated ERα, which leads to the inhibition of multiple ERα-signalling pathways, including genomic and non-genomic ERα activation and ERα phosphorylation, and the growth of ERα-positive breast cancer cells both in vitro and in vivo. More importantly, ERAP treatment suppresses tamoxifen resistance and enhances tamoxifen responsiveness in ERα-positive breast cancer cells. These findings suggest inhibiting the interaction between BIG3 and PHB2 may be a new therapeutic strategy for the treatment of luminal-type breast cancer.

ObjectiveMetabolomics is a promising approach to the identification of biomarkers in plasma. Here, we performed a population-based, cross-sectional study to identify potential biomarkers of alcohol intake and alcohol-induced liver injury by metabolomic profiling using capillary electrophoresis-mass spectrometry (CE-MS).MethodsFasting plasma samples were collected from 896 Japanese men who participated in the baseline survey of the Tsuruoka Metabolomics Cohort Study, and 115 polar metabolites were identified and absolutely quantified by CE-MS. Information on daily ethanol intake was collected through a standardized, self-administered questionnaire. The associations between ethanol intake and plasma concentration of metabolites were examined. Relationships between metabolite concentrations or their ratios and serum liver enzyme levels in the highest ethanol intake group (>46.0 g/day) were then examined by linear regression analysis. Replication analysis was conducted in 193 samples collected from independent population of this cohort.ResultsNineteen metabolites were identified to have an association with daily alcohol consumption both in the original and replication population. Three of these metabolites (threonine, glutamine, and guanidinosuccinate) were found to associate well with elevated levels of serum liver enzymes in the highest ethanol intake group, but not in the non-drinker group. We also found that the glutamate/glutamine ratio had a much stronger relation to serum γ-glutamyltransferase, aspartate transaminase, and alanine transaminase than glutamate or glutamine alone (standardized beta = 0.678, 0.558, 0.498, respectively).ConclusionsWe found 19 metabolites associated with alcohol intake, and three biomarker candidates (threonine, guanidinosuccinate and glutamine) of alcohol-induced liver injury. Glutamate/glutamine ratio might also be good biomarker.Electronic supplementary materialThe online version of this article (doi:10.1007/s12199-015-0494-y) contains supplementary material, which is available to authorized users.

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Breast cancer is the most common cancer among women worldwide; the breast cancer incidence and death rates for Japanese were 102.8 and 17.1 per 100 000 population, respectively, in the year 2006.(1,2) Incidence of breast cancer is increasing in most countries including the USA and Japan, and the increasing rate is much higher in countries where its incidence was previously low.(1,2) It has been known that breast cancer is a hormonedependent disease, and estrogens through an interaction with estrogen receptor (ER) drastically enhance the proliferative and metastatic activity in breast tumor cells.(3,4) However, despite the clinical benefit of interruption of the ER function with synthetic anti-estrogen drugs such as tamoxifen, the precise mechanism of an estrogen/ER signaling pathway in breast cancer progression is not well understood. Therefore, further characterization of the pathophysiologic roles of this pathway and development of novel drugs targeting this pathway should be eagerly expected to provide better management for breast cancer patients.Gene-expression profile analysis can generate a considerable amount of information for characterizing the nature of individual cancers; such information should be applied for extraction of potential molecular targets for improving clinical strategies to treat neoplastic diseases.(5,6) Through the genome-wide expression analysis of a large number of microdissected clinical cancer materials, we have identified dozens of genes that function as oncogenes in the process of development and/or progression of breast cancer, (7)(8)(9)(10)(11) bladder cancer, (12,13) synovial sarcomas, (14,15) testicular seminoma, (19,20) and identified dozens of molecules that were overexpressed in a great majority of breast cancers and were low or undetectably expressed in normal human organs.Among many over-expressed genes in breast cancers, we report in this study identification and characterization of a novel gene, brefeldin A-inhibited guanine nucleotide-exchange protein 3 (BIG3), a novel member of the BIG1/Sec7p subfamily of ADP ribosylation factor-GTP exchange factors (ARF-GEFs), to be a key molecule regulating an estrogen/estrogen receptor (ER) signaling pathway in breast cancer. We also demonstrate an interaction of BIG3 with prohibitin 2/repressor of estrogen receptor activity (PHB2/REA) protein, and that their interaction can enhance the ERα transcriptional activity. Our findings imply BIG3 to be a promising target for development of novel anti-cancer drugs for breast cancer. Materials and MethodsCell lines and clinical samples. Human breast cancer cell lines HCC1937, MCF-7, MDA-MB-231, SK-BR-3, T47D, BT-549, HCC1395, MDA-MB-157, BT-20, MDA-MB-453, ZR-75-1, BT-483, BT-474, HCC1143, HCC1500, HCC1599, and OCUB-F, as well as African green monkey SV40-transfected kidney fibroblast cell line, COS-7, were purchased from American Type Culture Collection (ATCC, Rockville, MD, USA), and cultured under their respective depositors' recommendations. All cells were cultured according to previ...