Diverse Alkyl-Silyl Cross-Coupling via Homolysis of Unactivated C(sp3)-O Bonds with the Cooperation of Gold Nanoparticles and Amphoteric Zirconium Oxides.

Since C(sp3)-O bonds are a ubiquitous chemical motif in both natural and artificial organic molecules, the universal transformation of C(sp3)-O bonds will be a key technology for achieving carbon neutrality. We report herein that gold nanoparticles supported on amphoteric metal oxides, namely, ZrO2, efficiently generated alkyl radicals via homolysis of unactivated C(sp3)-O bonds, which consequently promoted C(sp3)-Si bond formation to give diverse organosilicon compounds. A wide array of esters and ethers, which are either commercially available or easily synthesized from alcohols participated in the heterogeneous gold-catalyzed silylation by disilanes to give diverse alkyl-, allyl-, benzyl-, and allenyl silanes in high yields. In addition, this novel reaction technology for C(sp3)-O bond transformation could be applied to the upcycling of polyesters, i.e., the degradation of polyesters and the synthesis of organosilanes were realized concurrently by the unique catalysis of supported gold nanoparticles. Mechanistic studies corroborated the notion that the generation of alkyl radicals is involved in C(sp3)-Si coupling and the cooperation of gold and an acid-base pair on ZrO2 is responsible for the homolysis of stable C(sp3)-O bonds. The high reusability and air tolerance of the heterogeneous gold catalysts as well as a simple, scalable, and green reaction system enabled the practical synthesis of diverse organosilicon compounds.

Concurrent minimal change disease and retroperitoneal liposarcoma successfully treated by tumor resection and steroid therapy.

A 54-year-old Japanese woman developed simultaneous abdominal distension and bilateral leg edema. Her medical history and results of periodic medical check-up were unremarkable. Blood tests revealed severe hypoproteinemia and acute kidney injury, and urinalysis revealed 4+ proteinuria and 2+ hematuria. Abdominal computed tomography revealed a large intra-abdominal mass with fat tissue density. She underwent emergency tumor excision, splenectomy, and distal pancreatectomy. However, hypoproteinemia and acute kidney injury worsened. Therefore, she was transferred to the nephrology division for confirmation of diagnosis and for treatment of acute kidney injury and nephrotic syndrome. We conducted percutaneous kidney biopsy and diagnosed minimal change disease (MCD). Intravenous prednisolone was started, and heavy proteinuria and systemic edema were gradually alleviated. She achieved complete remission 2 months later, and oral prednisolone was tapered. Histopathological diagnosis of abdominal tumor was dedifferentiated liposarcoma of retroperitoneal origin. Immunohistochemical staining revealed strong expression of vascular endothelial growth factor in the tumor cells in the dedifferentiated component. Currently, her clinical course is stable without recurrence of liposarcoma and nephrotic syndrome. MCD develops in patients with Hodgkin's lymphoma, solid organ cancers, hematological malignancies, and thymoma, whereas concurrent MCD and liposarcoma are rare. Remission of nephrotic syndrome and normalized kidney function induced by steroid therapy are important for better management of patients with malignancy.

MicroRNA-203 regulates melanosome transport and tyrosinase expression in melanoma cells by targeting kinesin superfamily protein 5b.

MicroRNA (miR)-203 is known to be downregulated and to act as an anti-oncomir in melanoma cells. At present, we found that exogenous miR-203 increased pigmentation and protein expression levels of the melanoma antigen recognized by T cells (Melan-As/MART1s) and/or tyrosinase (TYR) in the human melanoma cells tested. Inversely, treatment with an inhibitor of miR-203 downregulated the expression level of TYR. The target gene of miR-203 involved in the mechanism was kinesin superfamily protein 5b (kif5b), which was revealed by gene silencing using short interfering RNA and luciferase activity assay. Furthermore, immunocytochemistry showed obvious accumulation of melanosomes around nuclei of human melanoma Mewo cells transfected with miR-203 or siR-kif5b. Importantly, treatment with the miR-203 inhibitor, but not miR-203, exhibited effects on human epidermal melanocytes isolated from lightly pigmented adult skin similar to those on melanoma cells. In addition, the data indicated that exogenous miR-203 also negatively regulated the cAMP response element-binding protein 1 (CREB1)/microphthalmia-associated transcription factor (MITF)/Rab27a pathway, which is one of the main pathways active in melanoma cells. In conclusion, our data indicated that anti-oncogenic miR-203 had a pivotal role in melanoma through reducing melanosome transport and promoting melanogenesis by targeting kif5b and through negative regulation of the CREB1/MITF/Rab27a pathway.

Anti-cancer effects of naturally occurring compounds through modulation of signal transduction and miRNA expression in human colon cancer cells.

Much evidence indicates that various naturally occurring compounds have an anti-cancer effect, but the detailed mechanisms are not well understood. In this study, we selected anti-cancer phytochemicals such as epigallocatechin-3-gallate (EGCG), resveratrol (RES) and α-mangostin (α-M), all of which are well-characterized chemopreventive agents. We sought to elucidate the mechanism of their anti-cancer effects and the synergistic effects obtained by combined treatment with the anti-cancer drug 5-fluorouracil (5-FU) in three human colon cancer cell lines. The numbers of viable cells were consistently decreased by the treatment with EGCG, RES or α-M at more than 10 µM in all three cell lines tested. All compounds mainly induced apoptosis and suppressed the PI3K/Akt signaling pathway. Additionally, α-M, which had the greatest PI3K/Akt-suppressing activity, also suppressed MAP kinase (MAPK)/Erk1/2 signaling. Importantly, the combination treatment with RES and 5-FU induced a remarkably synergistic enhancement of growth inhibition and apoptosis through the additional suppression of the MAPK/Erk1/2 signaling pathway in colon cancer DLD-1 cells. Interestingly, RES increased the intracellular expression level of miR-34a, which down-regulated the target gene E2F3 and its downstream Sirt1, resulting in growth inhibition. These findings indicate that these compounds functioned as chemosensitizers when combined with anti-cancer drugs through the modulation of apoptotic and growth-related signaling pathways. Also, RES exerted its anti-cancer activity in part through a newly defined mechanism, i.e., the miR-34a/E2F3/Sirt1 cascade.

Replacement treatment with microRNA-143 and -145 induces synergistic inhibition of the growth of human bladder cancer cells by regulating PI3K/Akt and MAPK signaling pathways.

We recently reported that both microRNA (miR)-143 and -145 are downregulated in human bladder cancer T24 cells and that miR-143 targets ERK5. In this study, we assessed the anti-tumor effects of combination treatment with miR-143 and -145 on bladder cancer cell lines T24, SNK57, and NKB1, in which the expression levels of miR-143 and -145 are downregulated. The ectopic expression of both miR-143 and -145 led to a significantly synergistic growth inhibition of T24 and NKB1 cells, but not that of SNK57 cells with the levels of miR-143 and -145 higher than those in T24 and NKB1 cells. The MAPK signaling pathway in NKB1 cells and both PI3K/Akt and MAPK signaling pathways in T24 cells were synergistically repressed by the co-treatment with miR-143 and -145. We newly elucidated that miR-143 targeted akt and that miR-145 targeted integrin-linked kinase (ilk) in T24 cells based on the results of a luciferase activity assay. Silencing of ilk significantly inhibited the growth of all the bladder cancer cells tested. Also, the level of phosphorylated ERK1/2 in T24 cells and that of phosphorylated Akt in SNK57 and NKB1 cells were decreased by ilk silencing. This study has provided novel important evidence with regard to the functions of anti-oncogenic miR-143 and -145 and also suggests the possible use of miR-143 and -145 for combination replacement therapy in cancers in which both miRNAs are downregulated.

Anti-oncogenic microRNA-203 induces senescence by targeting E2F3 protein in human melanoma cells.

MicroRNAs regulate gene expression by repressing translation or directing sequence-specific degradation of their complementary mRNA. We recently reported that miR-203 is down-regulated, and its exogenous expression inhibits cell growth in canine oral malignant melanoma tissue specimens as well as in canine and human malignant melanoma cells. A microRNA target database predicted E2F3 and ZBP-89 as putative targets of microRNA-203 (miR-203). The expression levels of E2F3a, E2F3b, and ZBP-89 were markedly up-regulated in human malignant melanoma Mewo cells compared with those in human epidermal melanocytes. miR-203 significantly suppressed the luciferase activity of reporter plasmids containing the 3'-UTR sequence of either E2F3 or ZBP-89 complementary to miR-203. The ectopic expression of miR-203 in melanoma cells reduced the levels of E2F3a, E2F3b, and ZBP-89 protein expression. At the same time, miR-203 induced cell cycle arrest and senescence phenotypes, such as elevated expression of hypophosphorylated retinoblastoma and other markers for senescence. Silencing of E2F3, but not of ZBP-89, inhibited cell growth and induced cell cycle arrest and senescence. These results demonstrate a novel role for miR-203 as a tumor suppressor acting by inducing senescence in melanoma cells.