Publications by authors named "Takamitsu Sasaki"

The demand for alternatives to animal testing has increased, but there has been no significant progress in developing alternatives for repeated-dose toxicity tests despite their importance in chemical risk assessment. A comprehensive analysis of existing toxicity studies is the first step toward understanding toxicity and developing alternatives. However, such an analysis has yet to be performed for industrial chemicals.

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The prediction of cytochrome P450 inhibition by a computational (quantitative) structure-activity relationship approach using chemical structure information and machine learning would be useful for toxicity research as a simple and rapid tool. However, there are few models focusing on the species differences between rat and human in the P450s inhibition. This study aimed to establish models to classify chemical substances as inhibitors or non-inhibitors of various rat and human P450s, using only molecular descriptors.

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Nutritional interventions are one focus of sarcopenia treatment. As medium-chain fatty acids (MCFAs) are oxidized in the mitochondria and produce energy through oxidative phosphorylation (OXPHOS), they are key parts of nutritional interventions. We investigated the in vitro effects of three types of MCFA, caprylic acid (C8), capric acid (C10), and lauric acid (C12), in skeletal muscle cells.

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β-Casomorphin-7 (BCM), a breakdown product of milk β-casein, exhibits opioid activity. Opioids are known to affect the immune system, but the effects of BCM on ulcerative colitis (UC) are not clear. We examined the effects of BCM on mucosal immunity using a mouse dextran sulfate sodium-induced colitis model and an in vitro CD8+ T cell activation model.

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Article Synopsis
  • This study investigated the link between aging and cancer sarcopenia, revealing that both conditions show similar aging marker changes in skeletal muscles.
  • The research found significant oxidative stress, fibrosis, and mitochondrial DNA damage in mouse models, including deletions affecting the electron transport chain.
  • Neutralizing inflammatory cytokines (HMGB1 and TNFα) in the mouse cachexia model reduced oxidative stress and mitochondrial damage, suggesting these inflammatory factors accelerate aging-related muscle deterioration in cancer.
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Abnormalities in mucosal immunity are involved in the onset and progression of ulcerative colitis (UC), resulting in a high incidence of colorectal cancer (CRC). While high-mobility group box-1 (HMGB1) is overexpressed during colorectal carcinogenesis, its role in UC-related carcinogenesis remains unclear. In the present study, we investigated the role of HMGB1 in UC-related carcinogenesis and sporadic CRC.

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  • Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with a 5-year survival rate below 10%, and drug resistance complicates treatment efforts.
  • The study developed MIA-GEM cells, a gemcitabine-resistant PDAC cell line, and found increased expression of AKT3 and dysregulated AKT signaling, which contributed to the cells' resistance.
  • Elevated nuclear expression of AKT3 in GEM-resistant PDAC cases is linked to poorer patient prognosis, indicating its potential as a therapeutic target and a marker for drug resistance in PDAC.
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Patients with cancer die from cardiac dysfunction second only to the disease itself. Cardiotoxicity caused by anticancer drugs has been emphasized as a possible cause; however, the details remain unclear. To investigate this mechanism, we treated rat cardiomyoblast H9c2 cells with sunitinib, lapatinib, 5-fluorouracil, and cisplatin to examine their effects.

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Our study was designed to examine the correlation between single nucleotide polymorphism (SNP) in the endoplasmic reticulum aminopeptidase 1 (ERAP1) gene, specifically focusing on rs27434, and plural tissue weight. We conducted this investigation using autopsy samples from the Japanese population. Blood samples were collected from 178 Japanese subjects who had undergone autopsies in Shimane Prefecture.

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Drug-induced liver injury (DILI) is a major cause of drug development discontinuation and drug withdrawal from the market, but there are no golden standard methods for DILI risk evaluation. Since we had found the association between DILI and CYP1A1 or CYP1B1 inhibition, we further evaluated the utility of cytochrome P450 (P450) inhibition assay data for DILI risk evaluation using decision tree analysis.The inhibitory activity of drugs with DILI concern (DILI drugs) and no DILI concern (no-DILI drugs) against 10 human P450s was assessed using recombinant enzymes and luminescent substrates.

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Constitutive androstane receptor (CAR), a nuclear receptor predominantly expressed in the liver, is activated by diverse chemicals and induces hepatocyte proliferation and hepatocarcinogenesis in rodents. However, the underlying mechanism responsible for CAR-dependent hepatocyte proliferation remains unclear. Importantly, this phenomenon has not been observed in the human liver.

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N-methyl-glycine (sarcosine) is known to promote metastatic potential in some cancers; however, its effects on bladder cancer are unclear. T24 cells derived from invasive cancer highly expressed GNMT, and S-adenosyl methionine (SAM) treatment increased sarcosine production, promoting proliferation, invasion, anti-apoptotic survival, sphere formation, and drug resistance. In contrast, RT4 cells derived from non-invasive cancers expressed low GNMT, and SAM treatment did not produce sarcosine and did not promote malignant phenotypes.

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The creatine shuttle translocates the energy generated by oxidative phosphorylation to the cytoplasm via mitochondrial creatine kinase (MTCK) and creatine kinase B (CKB) in the cytoplasm. It is not apparent how the creatine shuttle is related to cancer. Here, we analyzed the expression and function of CKB and MTCK in colorectal cancer (CRC) and investigated the role of the creatine shuttle in CRC.

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Although gemcitabine (GEM) is widely used in chemotherapy for pancreatic ductal adenocarcinoma (PDA), drug resistance restricts its clinical effectiveness. To examine the mechanism of GEM resistance, we established two GEM-resistant cell lines from human PDA cells by continuous treatment with GEM and CoCl-induced chemical hypoxia. One resistant cell line possessed reduced energy production and decreased mitochondrial reactive oxygen species levels, while the other resistant cell line possessed increased stemness.

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Gastric cancers are strongly associated with infection, with intestinal metaplasia characterizing the background mucosa in most cases. However, only a subset of intestinal metaplasia cases proceed to carcinogenesis, and the characteristics of high-risk intestinal metaplasia that link it with gastric cancer are still unclear. We examined telomere reduction in five gastrectomy specimens using fluorescence in situ hybridization, and identified areas with localized telomere loss (outside of cancerous lesions), which were designated as short telomere lesions (STLs).

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Article Synopsis
  • The study investigates the roles of the constitutive androstane receptor (CAR) in drug metabolism and liver tumor development, focusing on identifying both direct and indirect activators of rat CAR (rCAR).
  • A mutant form of rCAR called rCAR-3A-G354Q was found to have low background activity but high responsiveness to ligands, allowing researchers to test various compounds for their effect on CAR activation.
  • The research also highlighted six compounds that did not activate the rCAR mutant directly but showed potential as indirect activators, indicating a method for evaluating rCAR activation through measuring target gene expression in rat and human liver cells.
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Pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis because it is often detected at an advanced stage, and drug resistance interferes with treatment. However, the mechanism underlying drug resistance in PDAC remains unclear. Here, we investigated metabolic changes between a parental PDAC cell line and a gemcitabine (GEM)-resistant PDAC cell line.

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Retinoic acid, an active form of vitamin A, plays very important roles in mammalian embryogenesis. The concentration of retinoic acid is extremely low and strictly regulated by enzymes of cytochrome P450 (CYP) family, CYP26s (CYP26A1, CYP26B1 and CYP26C1) in the cells. Therefore, it is thought that changes in CYP26s activities due to exposure to a wide variety of drugs and chemicals exhibit teratogenicity.

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High mobility group box-1 (HMGB1) is known to be a chemotactic factor for mesenchymal stem/stromal cells (MSCs), but the effect of post-translational modification on its function is not clear. In this study, we hypothesized that differences in the oxidation state of HMGB1 would lead to differences in the function of MSCs in cancer. In human colorectal cancer, MSCs infiltrating into the stroma were correlated with liver metastasis and serum HMGB1.

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The use of molecular-targeted drugs in the treatment of gastric cancer is increasing. However, the variety of molecular-targeted drugs in gastric cancer is still limited, and the development of new molecular-targeted therapies is required. The effect of combining sunitinib (SUN) with pterostilbene (PTE) on the human gastric cancer cell lines TMK1 and MKN74 was examined in in vitro and in vivo.

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Linoleic acid (LA) has been shown to cause inflammation and promote development of colorectal cancer (CRC). Moreover, many literatures show that LA is associated with cancer metastasis. Metastatic cancer cells have high stemness, suggesting that LA might affect the stemness of cancer cells.

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Article Synopsis
  • Cancer dormancy is when cancer cells are inactive but can re-emerge after a period, posing challenges for treatment.
  • Long-term treatment with linoleic acid (LA) causes certain cancer cells, like the colorectal cancer line CT26, to enter a quiescent state, which is linked to lower energy production and is regulated by microRNA (miR-494).
  • Research indicates that LA induces miR-494 expression, which may help explain how LA promotes cancer dormancy, especially in relation to tumor growth in mice and varying levels of miR-494 in human colorectal cancer cases.
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Background: PXR is a xenobiotic-responsive nuclear receptor that controls the expression of drug-metabolizing enzymes. Drug-induced activation of PXR sometimes causes drug-drug interactions due to the induced metabolism of co-administered drugs. Our group recently reported a possible drug-drug interaction mechanism via an interaction between the nuclear receptors CAR and PPARα.

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Gastric hyperplastic polyps (GHP) are frequently found to be benign polyps and have been considered to have a low carcinogenic potential. The characteristics of the hyperplastic polyp-associated gastric cancer (HPAGC) remain unclear. Therefore, we analyzed samples from 102 GHP patients and identified 20 low-grade atypical GHPs (19.

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β-Casomorphin-7 (BCM) is a degradation product of β-casein, a milk component, and has been suggested to affect the immune system. However, its effect on mucosal immunity, especially anti-tumor immunity, in cancer-bearing individuals is not clear. We investigated the effects of BCM on lymphocytes using an in vitro system comprising mouse splenocytes, a mouse colorectal carcinogenesis model, and a mouse orthotopic colorectal cancer model.

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