Biology subjects

Yamaguchi, A.

Publications and source records attributed to Yamaguchi, A..

22 records · Page 2Linked to original sources

bioRxiv2021

Role of miR-181c in Diet-Induced Obesity Through Regulation of Lipid Synthesis in Liver

We recently identified a nuclear-encoded miRNA (miR-181c) in cardiomyocytes that can translocate into mitochondria to regulate mitochondrial gene (mt-COX1), and influence obesity-induced cardiac dysfunction through mitochondrial pathway. Liver plays a pivotal role during obesity. Therefore, we hypothesized that miR-181c plays an important role in pathophysiological complications associated with obesity. We used miR-181c/d-/- mice to study the miR-181c role in lipogenesis in hepatocytes during diet-induced obesity (DIO). Indirect calorimetric measurements were made during the 26 weeks high fat diet (HFD) exposure. qPCR was performed to examine the gene expression involved in lipid synthesis. Here, we show that miR-181c/d-/- mice are not protected against all metabolic consequences of HFD exposure. After 26 weeks of the HFD, miR-181c/d-/- mice had a significantly higher body fat (%) compared to WT. Glucose tolerance tests showed hyperinsulinemia and hyperglycemia, indicative of insulin insensitivity in the miR-181c/d-/- mice. HFD-fed miR-181c/d-/- mice had higher serum and liver triglyceride levels compared to HFD-fed WT mice. qPCR data demonstrated that several genes which are regulated by isocitrate dehydrogenase 1 (IDH1) were upregulated in miR-181c/d-/- liver compared to WT liver. Furthermore, an AAV-8 was used to deliver miR-181c, in vivo, to validate the potential role of miR-181c in the liver. miR-181c delivery attenuate the lipogenesis by downregulating the same lipid synthesis genes in the liver. In hepatocytes, miR-181c regulates lipid biosynthesis by targeting IDH1. Taken together, the data indicate that overexpression of miR-181c can be beneficial for various lipid metabolism disorders.

cell biology↗

bioRxiv2020

Antibody-drug conjugates with dual payloads for combating breast tumor heterogeneity and drug resistance

Breast tumors generally consist of a diverse population of cells with varying gene expression profiles. Breast tumor heterogeneity is a major factor contributing to drug resistance, recurrence, and metastasis after chemotherapy. Antibody-drug conjugates (ADCs) are emerging chemotherapeutic agents with striking clinical success, including T-DM1 for HER2-positive breast cancer. However, these ADCs often suffer from issues associated with intratumor heterogeneity. Here, we show that homogeneous ADCs containing two distinct payloads are a promising drug class for addressing this clinical challenge. Our conjugates show HER2-specific cell killing potency, desirable pharmacokinetic profiles, minimal immunogenicity, and marginal toxicity at therapeutic doses. Notably, a dual-drug ADC exerts greater treatment effect and survival benefit than does co-administration of two single-drug variants in a xenograft mouse model representing intratumor HER2 heterogeneity and elevated drug resistance. Our findings highlight the therapeutic potential of the dual-drug ADC format for treating refractory breast cancer and perhaps other cancers.

bioengineering↗

bioRxiv2019

AIRE is induced in oral squamous cell carcinoma and promotes cancer gene expression.

Autoimmune regulator (AIRE) is a transcriptional regulator that is primarily expressed in medullary epithelial cells, where it induces tissue-specific antigen expression. Under pathological conditions, AIRE expression is induced in epidermal cells and promotes skin tumor development in association with stress-responsive keratin KRT17. This study aimed to clarify the role of AIRE in the pathogenesis of oral squamous cell carcinoma (OSCC). AIRE expression was evaluated in seven OSCC cell lines and in OSCC tissue specimens. Transient or constitutive expression of AIRE in 293A cells induced KRT17 expression. cDNA microarray analysis of 293A cells stably expressing AIRE revealed that STAT1 and ICAM1 were significantly upregulated by AIRE. Expression of KRT17, STAT1, ICAM1, MMP9, CXCL10, and CXCL11 was elevated in 293A cells stably expressing AIRE, and conversely, was decreased in AIRE-knockout HSC3 OSCC cells when compared to the respective controls. Upregulation of KRT17, STAT1, and ICAM in OSCC cells was confirmed in tissue specimens by immunohistochemistry. We provide evidence that AIRE exerts transcriptional control in cooperation with ETS1. Expression of STAT1, ICAM1, CXCL10, and MMP9 was increased in 293A cells upon Ets1 transfection, and coexpression of AIRE resulted in enhanced expression of STAT1. AIRE coprecipitated with ETS1 in a modified immunoprecipitation assay using formaldehyde crosslinking. Chromatin immunoprecipitation and quantitative PCR analysis revealed that promoter fragments of STAT1, ICAM1, CXCL10, and MMP9 were enriched in the AIRE precipitates. In oral cancer cells, ETS1 was diffusely located in the nucleus and partially overlapped with dot-like AIRE accumulation sites. Nuclear translocation of AIRE was promoted by cotransfection with Ets1. These results indicate that AIRE is induced in OSCC and supports cancer-related gene expression in cooperation with ETS1. This is a novel function of AIRE in extrathymic tissues under the pathological condition.

cancer biology↗

bioRxiv2018

Proximity proteomics identifies cancer cell membrane cis-molecular complex as a potential cancer target

Cancer-specific antigens expressed in the cell membrane have been used as targets for several molecular targeted strategies in recent years with remarkable success. To develop more effective cancer treatments, novel targets and strategies for targeted therapies are needed. Here, we examined the cancer cell membrane-resident \"cis-bimolecular complex\" as a possible cancer target (cis-bimolecular cancer target: BiCAT) using proximity proteomics, a technique that has attracted attention in recent years. BiCATs were detected using a previously developed method, termed the enzyme-mediated activation of radical source (EMARS), to label the components proximal to a given cell membrane molecule. EMARS analysis identified some BiCATs, such as close homolog of L1 (CHL1), fibroblast growth factor 3 (FGFR3) and 2 integrin, which are commonly expressed in mouse primary lung cancer cells and human lung squamous cell carcinoma cells. Analysis of cancer specimens from 55 lung cancer patients revealed that approximately half of patients were positive for these BiCATs. In vitro simulation of effective drug combinations used for multiple drug treatment strategy was performed using reagents targeted to BiCAT molecules. The combination treatment based on BiCAT information moderately suppressed cancer cell proliferation compared with single administration, suggesting that the information about BiCATs in cancer cells is profitable for the appropriate selection of the combination among molecular targeted reagents. Thus, BiCAT has the possibility to make a contribution to several molecular targeted strategies in future.

biochemistry↗