MHY2251, a New SIRT1 Inhibitor, Induces Apoptosis via JNK/p53 Pathway in HCT116 Human Colorectal Cancer Cells

Sirtuins (SIRTs) belong to the nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase family. They are key regulators of cellular and physiological processes, such as cell survival, senescence, differentiation, DNA damage and stress response, cellular metabolism, and aging. SIRTs also influence carcinogenesis, making them potential targets for anticancer therapeutic strategies. In this study, we investigated the anticancer properties and underlying molecular mechanisms of a novel SIRT1 inhibitor, MHY2251, in human colorectal cancer (CRC) cells. MHY2251 reduced the viability of various human CRC cell lines, especially those with wild-type TP53. MHY2251 inhibited SIRT1 activity and SIRT1/2 protein expression, while promoting p53 acetylation, which is a target of SIRT1 in HCT116 cells. MHY2251 treatment triggered apoptosis in HCT116 cells. It increased the percentage of late apoptotic cells and the sub-G1 fraction (as detected by flow cytometric analysis) and induced DNA fragmentation. In addition, MHY2251 upregulated the expression of FasL and Fas, altered the ratio of Bax/Bcl-2, downregulated the levels of pro-caspase-8, -9, and -3 proteins, and induced subsequent poly(ADP-ribose) polymerase cleavage. The induction of apoptosis by MHY2251 was related to the activation of the caspase cascade, which was significantly attenuated by pre-treatment with ZVAD-FMK, a pan-caspase inhibitor. Furthermore, MHY2251 stimulated the phosphorylation of c-Jun N-terminal kinase (JNK), and MHY2251-triggered apoptosis was blocked by pre-treatment with SP600125, a JNK inhibitor. This finding indicated the specific involvement of JNK in MHY2251-induced apoptosis. MHY2251 shows considerable potential as a therapeutic agent for targeting human CRC via the inhibition of SIRT1 and activation of JNK/p53 pathway.

SH2 domain–containing adaptor protein B expressed in dendritic cells is involved in T-cell homeostasis by regulating dendritic cell–mediated Th2 immunity

PURPOSE: The Src homology 2 domain–containing adaptor protein B (SHB) is widely expressed in immune cells and acts as an important regulator for hematopoietic cell function. SHB silencing induces Th2 immunity in mice. SHB is also involved in T-cell homeostasis in vivo. However, SHB has not yet been studied and addressed in association with dendritic cells (DCs). MATERIALS AND METHODS: The effects of SHB expression on the immunogenicity of DCs were assessed by Shb gene silencing in mouse bone marrow–derived DCs (BMDCs). After silencing, surface phenotype, cytokine expression profile, and T-cell stimulation capacity of BMDCs were examined. We investigated the signaling pathways involved in SHB expression during BMDC development. We also examined the immunogenicity of SHB-knockdown (SHB(KD)) BMDCs in a mouse atopic dermatitis model. RESULTS: SHB was steadily expressed in mouse splenic DCs and in in vitro–generated BMDCs in both immature and mature stages. SHB expression was contingent on activation of the mitogen- activated protein kinase/Foxa2 signaling pathway during DC development. SHB(KD) increased the expression of MHC class II and costimulatory molecules without affecting the cytokine expression of BMDCs. When co-cultured with T cells, SHB(KD) in BMDCs significantly induced CD4+ T-cell proliferation and the expression of Th2 cytokines, while the regulatory T cell (Treg) population was downregulated. In mouse atopic dermatitis model, mice inoculated with SHB(KD) DCs developed more severe symptoms of atopic dermatitis compared with mice injected with control DCs. CONCLUSION: SHB expression in DCs plays an important role in T-cell homeostasis in vivo by regulating DC-mediated Th2 polarization.

Experience of Bloodless Medicine and Surgery in Soonchunhyang University / 대한진단검사의학회지

BACKGROUND: We established a bloodless center at Soonchunhyang University Hospital (SCH) in 1996 and have provided medical and surgical care for Jehovah's Witness patients. In this study, we evaluated their outcomes to provide the basis of bloodless medicine and surgery in Korea. METHODS: A retropective review of the medical records of 757 Jehovah's Witness patients admitted in the SCH Bloodless Center from December 1996 to July 2003 was performed. RESULTS: Among 757 patients, 19 (2.5%) expired during treatment and 4 of them died of cardiopul-monary dysfunction secondary to anemia. As alternatives to blood transfusion, 85 (11.2%) patients were treated with iron, 81 (10.7%) with erythropoietin, 49 (6.5%) with aprotinin, 31 (4.1%) with hemodilution and 28 (3.7%) with cell saver. Four hundreds fifteen (54.8%) of 757 patients underwent surgery. The most frequently involved cinical department was Obstetric/Gynecology (23.8%). The ratio of female and the percentage of cases treated with alternatives to blood transfusion were higher in surgery group than non-surgery group patients.(Chi-square test, P<0.01) CONCLUSIONS: Most Jehovah's Witness patients were treated successfully in our bloodless center with various alternatives to blood transfusion, such as erythropoietin, intraoperative autotransfusion, acute normovolemic hemodilution etc. Collaboration and good communication among surgeons, anesthesiologists, hematologists and blood bank physicians are very important to provide qualified medical or surgical treatment to the patients who have a religious objection to receiving blood or blood-related products.