👤 Mitsuo Itakura

The prognosis of patients with high-grade or advanced-stage endometrial cancer remains poor. As cancer stem-like cells (CSCs) are thought to be associated with endometrial cancers, it is essential to investigate the molecular mechanisms that regulate endometrial CSCs. Dual-specificity phosphatase 6 (DUSP6) functions as a negative-feedback regulator of MAPK-ERK1/2 signaling, but its role in endometrial cancer remains unknown. We investigated whether DUSP6 is involved in cancer cell stemness using endometrial cancer cell lines and specimens from endometrial cancer patients. DUSP6 induced the expression of CSC-related genes including ALDH1, Nanog, SOX2 and Oct4A, increased the population of cells in the G0/G1 phase, and promoted sphere formation ability. DUSP6 knockdown resulted in reduced cell invasion and metastasis, whereas DUSP6 overexpression inhibited apoptosis under serum-free conditions. Moreover, DUSP6 decreased phosphorylated ERK1/2 and increased phosphorylated Akt levels, which potentially induces CSC features. In patients with endometrial cancers, DUSP6 expression was determined using immunohistochemistry, and based on the results, the patients were dichotomized into high- and low-DUSP6-expression groups. Progression-free survival and overall survival were significantly shorter in the high-DUSP6-expression group. These results suggest that DUSP6 has potential value as a biomarker of CSCs and as a target of therapies designed to eliminate CSCs in endometrial cancer. Show less

Epithelial-mesenchymal transition (EMT) is associated with cancer malignancies such as invasion, metastasis, and drug resistance. In this study, HCT116 human colorectal cancer cells were transduced with SLUG or SNAIL retroviruses, and EMT cells with mesenchymal morphology were established. The EMT cells showed a high invasive activity and resistance to several anticancer agents such as methotrexate, SN-38, and cisplatin. Furthermore, they contained about 1-10% side population (SP) cells that were not stained by Hoechst 33342. This SP phenotype was not stable; the isolated SP cells generated both SP and non-SP cells, suggesting a potential for differentiation. Gene expression analysis of SP cells suggested the alteration of genes that are involved in epigenetic changes. Therefore, we examined the effect of 74 epigenetic inhibitors, and found that two inhibitors, namely I-BET151 and bromosporine, targeting the bromodomain and extra-terminal motif (BET) proteins, decreased the ratio of SP cells to <50% compared with the control, without affecting the immediate efflux of Hoechst 33342 by transporters. In addition, compared with the parental cells, the EMT cells showed a higher sensitivity to I-BET151 and bromosporine. This study suggests that EMT development and SP phenotype can be independent events but both are regulated by BET inhibitors in SLUG- or SNAIL-transducted HCT116 cells. Show less

We recently reported distinct nature of high-density lipoproteins (HDL) subgroup particles with apolipoprotein (apo) A-I but not apoA-II (LpAI) and HDL having both (LpAI:AII) based on the data from 314 Japanese. While plasma HDL level almost exclusively depends on concentration of LpAI having 3 to 4 apoA-I molecules, LpAI:AII appeared with almost constant concentration regardless of plasma HDL levels having stable structure with two apoA-I and one disulfide-dimeric apoA-II molecules (Sci. Rep. 6; 31,532, 2016). The aim of this study is further characterization of LpAI:AII with respect to its role in atherogenesis. Association of LpAI, LpAI:AII and other HDL parameters with apoB-lipoprotein parameters was analyzed among the cohort data above. ApoA-I in LpAI negatively correlated with the apoB-lipoprotein parameters such as apoB, triglyceride, nonHDL-cholesterol, and nonHDL-cholesterol + triglyceride, which are apparently reflected in the relations of the total HDL parameters to apoB-lipoproteins. In contrast, apoA-I in LpAI:AII and apoA-II positively correlated to the apoB-lipoprotein parameters even within their small range of variation. These relationships are independent of sex, but may slightly be influenced by the activity-related CETP mutations. The study suggested that LpAI:AII is an atherogenic indicator rather than antiatherogenic. These sub-fractions of HDL are to be evaluated separately for estimating atherogenic risk of the patients. Show less

In an attempt to rectify the hyperglycemic state in obese insulin resistant db/db mice, a transgenic line was generated (db/db-CDK4(R24C)) that expresses a constitutively active form of cyclin-dependent kinase 4 (CDK4/R24C) under the control of the insulin promoter. Compared with non-transgenic db/db littermates, adult db/db-CDK4(R24C) mice show near-complete glycemic normalization and improved plasma lipid concentrations, but are also more susceptible to weight gain and have significantly lower plasma adiponection levels. They have striking islet hypertrophy and beta-cell hyperplasia, and retain an insulin secretory response during the glucose tolerance test. We examined the expression of several key regulatory transcription factor genes involved in lipid and glucose metabolism in insulin target tissues of db/db-CDK4(R24C) as well as db/db mice, and found that the expression levels of members of the peroxisome proliferator-activated receptor (PPAR) family are highly associated with metabolic alterations in a gene- and tissue-specific manner. We show for the first time that the Ppar-delta in skeletal muscle and white adipose tissues is transcriptionally down-regulated in db/db mice. The db/db-CDK4(R24C) mice present a novel model of leptin-resistant obesity with compensatory hyperinsulinemia and normalized blood glucose levels, and thus may be useful for future studies that aim to dissect relationships between insulin and leptin signaling. Show less

We studied the association of six common polymorphisms of four genes related to lipid metabolism with serum lipid levels. We selected single-nucleotide polymorphisms (SNPs) in the genes for cholesteryl ester transfer protein (CETP), lipoprotein lipase (LPL), hepatic lipase (LIPC), and apolipoprotein CIII (APOC3), and studied 2267 individuals randomly selected from the participants of Serum Lipid Survey 2000. There was a significant association of CETP polymorphism (D442G, Int14 +1 G --> A, and TaqIB), LPL polymorphism (S447X), and LIPC polymorphism (-514 --> CT) with HDL-cholesterol levels. We also found a significant association of LPL polymorphism (S447X) and APOC3 polymorphism (SstI) with triglyceride levels. This is the largest database showing the association of common genetic variants in lipid metabolism with serum lipid levels in the general Japanese population. Further study is necessary to elucidate the role of these gene polymorphisms in cardiovascular events. Show less

We report a Japanese boy who died at Day 28 of life because of severe carbamoyl phosphate synthetase I (CPS1) deficiency that was proven by enzyme assay. By analysis of cDNA and genomic DNA, he was shown to be a compound heterozygote with two point mutations of the CPS1 gene, 840G>C leading to an aberrant splicing and 1123C>T (predicting Q375X). The 840G>C was a mutation described in another Japanese family. Since his parents carried each mutation heterozygously, we performed prenatal diagnosis at 16 weeks of his mother's next gestation by multiplex PCR and melting curve analysis in a single capillary containing two-color fluorescent (LC-Red 640 and LC-Red 705) probes on LightCycler. We analyzed genomic DNA extracted from amniotic cells and found that the fetus was homozygous for the wild-type alleles. At term a healthy girl was born without hyperammonemia. Show less