Keiichi Hiramoto’s research while affiliated with Suzuka University of Medical Science and other places

Melanomas, which develop on malignant transformations of melanocytes, are highly malignant and prone to metastasis; therefore, effective drugs are required. The Momordica charantia (MC) extract has been shown to suppress cancer cell proliferation and invasion; however, the effect of the MC extract on melanoma in living organisms remains unclear. In this study, we investigated the mechanism underlying the amelioration of melanoma cell extravasation into mouse lungs by the MC extract. Male C57BL/6j mice (aged 8 weeks) were injected with B16 melanoma cells (1 × 105 cells/mouse). Subsequently, they were orally administered the MC extract daily for 2 weeks; mouse lung samples were obtained on the final day and analyzed. The MC extract ameliorated melanoma proliferation and infiltration into the lungs caused by melanoma cell treatment. It also increased phosphatase and tensin homolog deletion from chromosome 10 and suppressed paired box gene 3 (PAX3) and the phosphatidylinositol trisphosphate/RAC-alpha serine/threonine-protein kinase/mammalian target of rapamycin complex 1 signaling. Furthermore, it decreased microphthalmia-associated transcription factors and induced the suppression of cyclin-dependent kinase 2, hepatocyte growth factor receptor, B-cell/CLL lymphoma 2, and Ras-related proteins. Our findings suggest that the MC extract suppresses tumor survival genes by regulating PAX3, thereby ameliorating melanoma proliferation and invasion.

Diabetes mellitus includes type 1 and type 2 diabetes. Type 1 diabetes is an autoimmune disease affecting young people. Although several factors that worsen type 1 diabetes are known, information on the effects of blue light remains obscure. In this study, we investigated the effects of blue light irradiation on diabetes using mice with streptozotocin (STZ)-induced type 1 diabetes. Furthermore, we investigated the potential of selected compounds in rescuing the blue light-induced aggravation of diabetes. Blue light irradiation exacerbated type 1 diabetes. It activated insulin-like growth factor-1 and reactive oxygen species/caspase 3/apoptosis/endothelial-monocyte activating polypeptide II/neutrophil/neutrophil extracellular trap-associated cell death (NETosis) system signaling and increased the expression of angiopoietin-like protein 2 (Agptl2). These results indicate that blue light worsens type 1 diabetes by increasing NETosis production and the expression of Agptl2. Administration of pantethine or tranexamic acid prevented the blue light-induced worsening of type 1 diabetes by suppressing neutrophil production and Agptl2 expression. Our results provide insights into the effects of blue light on type 1 diabetes and highlight the potential of compounds that can be used in ameliorating such effects.

We live in a society where extending one’s healthy lifespan is becoming increasingly important. Momordica charantia (MC) extract contains many bioactive substances, such as vitamin D, phytosterols, glycosides, saponins, alkaloids, and triterpenes, and has various health-promoting effects, but its effect on extending a healthy lifespan is unknown. This study investigated the effects of MC extract on a healthy lifespan, focusing on bitter taste receptors and the mammalian target of rapamycin (mTOR). Male and female mice from the Institute of Cancer Research (ICR) were divided into control and MC-extract-treated groups, with the latter receiving oral doses of MC extract three times a week for two years. In aged male mice, MC extract increased the muscle mass and grip strength and prolonged the time to exhaustion. MC extract also enhanced the signaling from taste receptor type 2 member 1 (T2R1) to mTOR in muscle in both sexes, elevating the ribosomal protein S6 kinase beta-1 and ribosomal protein S6 levels. This T2R1/mTOR pathway works in protein synthesis and is important for increasing muscle mass. Conversely, the levels of eukaryotic translation initiation factor 4E-binding protein 1 and microtubule-associated protein light chain 3 decreased in both aged male and female mice after MC extract administration. These findings suggest that the administration of MC extract may extend the healthy lifespan of male mice, with bitter taste receptors and mTOR signaling playing key roles in this process.

Research on sex differences has increased across various fields, including cancer and its treatment domains. Reports have indicated sex differences in cancer incidence, survival rates, and the efficacy of anticancer drugs. However, such reports are limited, and in-depth assessments of the underlying mechanisms are still in progress. Although various chemotherapeutic regimens are applicable for breast cancer treatment, reports have surfaced regarding weight gain in female patients undergoing fluorouracil, epirubicin, cyclophosphamide (FEC) or cyclophosphamide, methotrexate, fluorouracil (CMF) therapy. We hypothesized the potential of 5-fluorouracil (5-FU) in weight gain and sex-related differences. To address this, we conducted experiments in mice to confirm weight gain and sex differences following 5-FU administration, and elucidate the underlying mechanisms. Our findings revealed weight gain and increased food intake in female mice following 5-FU administration. Additionally, female mice receiving 5-FU exhibited increased norepinephrine and α1- and α2-adrenergic receptor expression, reduced estradiol levels, and increased ghrelin levels. These results indicate 5-FU administration-induced sex differences in weight gain and implicate increased food intake because of increased norepinephrine and α1- and α2-adrenergic receptor expression, reduced estradiol levels, and a subsequent increase in ghrelin levels, which contribute to weight gain in female patients undergoing CMF therapy. Fullsize Image

We previously demonstrated that glycyrrhizin (GL) suppressed inflammation and carcinogenesis in an azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced murine model of colorectal cancer (CC). In this study, we found an accumulation of regulatory T cells (Tregs) in the spleen and suppression by GL in model mice. ICR mice were divided into four groups: Control, GL, CC, and GL-treated CC (CC+GL), and were sacrificed 20 weeks after AOM/DSS treatment. We measured spleen weight, areas of white and red pulp, and CD8⁺ T cells (cytotoxic T lymphocytes, CTL), and CD11c-positive cells (dendritic cells) in splenic tissues and forkhead box protein 3 (FoxP3)-positive cells (Tregs) in colorectal and splenic tissues. In all cases, the CC group showed a significant increase compared with those in Control group, and GL administration significantly attenuated this increase. These results indicate that Tregs accumulated in the spleen may participate in inflammation-related carcinogenesis by suppressing CTL. We also suggest that GL which binds to high-mobility group box 1 (HMGB1), suppresses carcinogenesis with decreasing Tregs in the spleen. Furthermore, there was an expression of FoxP3 in cancer cells, indicating that it may be involved in the malignant transformation of cancer cells.

Humans are persistently exposed to massive amounts of blue light via sunlight, computers, smartphones, and similar devices. Although the positive and negative effects of blue light on living organisms have been reported, its impact on learning and memory remains unknown. Herein, we examined the effects of widespread blue light exposure on the learning and memory abilities of blue light-exposed mice. Ten-week-old male ICR mice were divided into five groups (five mice/group) and irradiated with blue light from a light-emitting diode daily for 6 months. After 6 months of blue light irradiation, mice exhibited a decline in memory and learning abilities, assessed using the Morris water maze and step-through passive avoidance paradigms. Blue light-irradiated mice exhibited a decreased expression of the clock gene brain and muscle arnt-like 1 (Bmal1). The number of microglia and levels of M1 macrophage CC-chemokine receptor 7 and inducible nitric oxide synthase were increased, accompanied by a decrease in M2 macrophage arginase-1 levels. Levels of angiopoietin-like protein 2 and inflammatory cytokines interleukin-6, tumor necrosis factor-α, and interleukin-1β were elevated. Our findings suggest that long-term blue light exposure could reduce Bmal1 expression, activate the M1 macrophage/Angptl2/inflammatory cytokine pathway, induce neurodegeneration, and lead to a decline in memory.

The number of patients with type 2 diabetes is increasing worldwide. The mechanisms leading to type 2 diabetes and its complications is being researched; however, the pathological mechanisms of diabetes in the small intestine remain unclear. Therefore, we examined these pathological mechanisms in the small intestine using a mouse model of type 2 diabetes (KK-Ay/TaJcl) aged 10 and 50 weeks. The results showed that diabetes worsened with age in the mice with type 2 diabetes. In these mice, advanced glycation end products (AGEs) in the small intestine and mast cell expression increased, whereas diamine oxidase (DAO) decreased; increased tumor necrosis factor (TNF)-α and histamine levels in the plasma and small intestine were also detected. Additionally, the expression of zonula occludens (ZO)-1 and Claudin1 and cell adhesion molecules in the small intestine reduced. These results exacerbated with age. These findings indicate that type 2 diabetes causes AGE/mast cell/histamine and TNF-α signal transmission in the small intestine and decreases small intestinal wall cell adhesion molecules cause TNF-α and histamine to flow into the body, worsening the diabetic condition. In addition, this sequence of events is suggested to be strengthened in aged mice with type 2 diabetes, thus exacerbating the disease. These findings of this study may facilitate the elucidation of the pathological mechanisms of type 2 diabetes and its associated complications. Fullsize Image

Humans are exposed to large amounts of blue light from computers and smartphones. To date, no treatment has been developed for ameliorating nonmelanoma skin cancer induced by exposure to blue light. Here, we investigated the effects of tranexamic acid, carbazochrome, diisopropylamine dichloroacetate, and pantethine on blue light-induced skin cancer. The dorsal skin of male hairless mice was exposed to 40 kJ/m ² blue light thrice a week for 15 weeks after the application of 7,12-dimethylbenz[a]anthracene (DMBA). During the experimental period, mice were administered four types of test samples thrice a week. Skin cancer was induced in DMBA/blue light-treated mice, which improved upon administration of tranexamic acid or carbazochrome. In the mice treated with tranexamic acid or carbazochrome, the decrease in brain and muscle arnt-like 1 (Bmal1) level was suppressed, and the levels of neutrophils, beta 2 adrenergic receptor (β2-AR), intercellular adhesion molecule 1 (ICAM1), C-C motif chemokine ligand 2 (CCL2), and noradrenaline were affected by Bmal1. Furthermore, the administration of tranexamic acid and carbazochrome suppressed neutrophil extracellular trap-associated cell death (NETosis) caused by blue light irradiation. Hence, skin cancer induced by DMBA and blue light irradiation in mice can be improved by tranexamic acid or carbazochrome because tranexamic acid or carbazochrome modulates the noradrenaline/AR-β2/CCL2/ICAM1/neutrophil/NETosis signal transduction system regulated by the clock gene Bmal1.

UV-B radiation induces sunburn, and neutrophils are pivotal in this inflammation. In this study, we examined the potential involvement of neutrophil extracellular traps (NETs) in ultraviolet B (UVB)-induced skin inflammation, correlating the skin inflammation-mitigating effects of Hochu-ekki-to on UV-B irradiation and NETs. To elucidate NET distribution in the dorsal skin, male ICR mice, exposed to UVB irradiation, were immunohistologically analyzed to detect citrullinated histone H3 (citH3) and peptidylarginine deiminase 4 (PAD4). Reactive oxygen species (ROS) production in the bloodstream was analyzed. To establish the involvement of NET-released DNA in this inflammatory response, mice were UV-B irradiated following the intraperitoneal administration of DNase I. In vitro experiments were performed to scrutinize the impact of Hochu-ekki-to on A23187-induced NETs in neutrophil-like HL-60 cells. UV-B irradiation induced dorsal skin inflammation, coinciding with a significant increase in citH3 and PAD4 expression. Administration of DNase I attenuated UV-B-induced skin inflammation, whereas Hochu-ekki-to administration considerably suppressed the inflammation, correlating with diminished levels of citH3 and PAD4 in the dorsal skin. UV-B irradiation conspicuously augmented ROS and hydrogen peroxide (H2O2) production in the blood. Hochu-ekki-to significantly inhibited ROS and H2O2 generation. In vitro experiments demonstrated that Hochu-ekki-to notably inhibited A23187-induced NETs in differentiated neutrophil-like cells. Hence, NETs have been implicated in UV-B-induced skin inflammation, and their inhibition reduces cutaneous inflammation. Additionally, Hochu-ekki-to mitigated skin inflammation by impeding neutrophil infiltration and NETs in the dorsal skin of mice.