Single-cell transcriptomics unveil profiles and interplay of immune subsets in rare autoimmune childhood Sjögren's disease

Childhood Sjögren's disease represents critically unmet medical needs due to a complete lack of immunological and molecular characterizations. This study presents key immune cell subsets and their interactions in the periphery in childhood Sjögren's disease. Here we show that single-cell RNA sequencing identifies the subsets of IFN gene-enriched monocytes, CD4+ T effector memory, and XCL1+ NK cells as potential key players in childhood Sjögren's disease, and especially in those with recurrent parotitis, which is the chief symptom prompting clinical visits from young children. A unique cluster of monocytes with type I and II IFN-related genes is identified in childhood Sjögren's disease, compared to the age-matched control. In vitro regulatory T cell functional assay demonstrates intact functionality in childhood Sjögren's disease in contrast to reduced suppression in adult Sjögren's disease. Mapping this transcriptomic landscape and interplay of immune cell subsets will expedite the understanding of childhood Sjögren's disease pathogenesis and set the foundation for precision medicine.

PROTAC-mediated NR4A1 degradation as a novel strategy for cancer immunotherapy

An effective cancer therapy requires killing cancer cells and targeting the tumor microenvironment (TME). Searching for molecules critical for multiple cell types in the TME, we identified NR4A1 as one such molecule that can maintain the immune suppressive TME. Here, we establish NR4A1 as a valid target for cancer immunotherapy and describe a first-of-its-kind proteolysis-targeting chimera (PROTAC, named NR-V04) against NR4A1. NR-V04 degrades NR4A1 within hours in vitro and exhibits long-lasting NR4A1 degradation in tumors with an excellent safety profile. NR-V04 inhibits and frequently eradicates established tumors. At the mechanistic level, NR-V04 induces the tumor-infiltrating (TI) B cells and effector memory CD8+ T (Tem) cells and reduces monocytic myeloid-derived suppressor cells (m-MDSC), all of which are known to be clinically relevant immune cell populations in human melanomas. Overall, NR-V04-mediated NR4A1 degradation holds promise for enhancing anticancer immune responses and offers a new avenue for treating various types of cancers such as melanoma.

KDM6A Regulates Immune Response Genes in Multiple Myeloma

The histone H3K27 demethylase KDM6A is a tumor suppressor in multiple cancers, including multiple myeloma (MM). We created isogenic MM cells disrupted for KDM6A and tagged the endogenous protein to facilitate genome wide studies. KDM6A binds genes associated with immune recognition and cytokine signaling. Most importantly, KDM6A binds and activates NLRC5 and CIITA encoding regulators of Major Histocompatibility Complex (MHC) genes. Patient data indicate that NLRC5 and CIITA, are downregulated in MM with low KDM6A expression. Chromatin analysis shows that KDM6A binds poised and active enhancers and KDM6A loss led to decreased H3K27ac at enhancers, increased H3K27me3 levels in body of genes bound by KDM6A and decreased gene expression. Reestablishing histone acetylation with an HDAC3 inhibitor leads to upregulation of MHC expression, offering a strategy to restore immunogenicity of KDM6A deficient tumors. Loss of Kdm6a in murine RAS-transformed fibroblasts led to increased growth in vivo associated with decreased T cell infiltration.

Statement of significance

We show that KDM6A participates in immune recognition of myeloma tumor cells by directly regulating the expression of the master regulators of MHC-I and II, NLRC5 and CIITA. The expression of these regulators can by rescued by the HDAC3 inhibitors in KDM6A-null cell lines.

Abstract 571: Angiopoietin-like 4 as a potential therapeutic target for clear cell renal carcinoma

Renal cell carcinoma (RCC) is the 7th most common type of cancer, with over 400,000 new cases each year and 170,000 deaths worldwide. RCCs are grouped into several histological subtypes, with clear cell renal cell carcinoma (ccRCC) being the most common and most aggressive type. The first line of therapy for ccRCC is tyrosine kinase inhibitors (TKIs) which target multiple kinases including the VEGF receptor. The treatment can be used alone or in combination with immune checkpoint inhibitors. However, most patients develop resistance to the TKIs within six months of treatment. Therefore, our aim is to develop novel single or combinatorial therapies and discover ways to overcome the resistance to TKIs. By analyzing TCGA and published datasets from GEO, we found that angiopoietin-like 4 (ANGPTL4) is significantly elevated in both the WT and TKI-resistant ccRCC tumors. ANGPTL4 has been shown to participate in angiogenesis in several other tumor models, and blocking ANGPTL4 with an antibody in vitro, reduces the angiogenic potential of 786-O and RCC4 human ccRCC cell lines, suggesting a pro-angiogenic effect of ANGPTL4 in ccRCC. Knockout of ANGPTL4 in Caki-1 xenograft tumor model significantly reduced tumor angiogenesis and increased vessel normalization, as evidenced by increased expression of VEGFR2 and adhesion molecules on endothelial cells. The increased normalization of blood vessels is an indication of the therapeutic potential of combing anti-ANGPTL4 therapy with immune checkpoint inhibitors. Furthermore, both knockout of ANGPTL4 in 786-O cells and treatment of 786-O tumor-bearing mice with an ANGPTL4 blocking antibody significantly reduced tumor growth. To illustrate the mechanism of ANGPTL4-induced angiogenesis, we performed live cell receptor capturing to find cANGPTL4 binding partners on the cell membrane of human endothelial cells. After the mass spectrometry analysis, several novel receptors were found, and the top candidate is endothelial cell surface chemotaxis receptor (ECSCR), which is highly expressed on endothelial and adipocytes. Previous studies have shown that ECSCR can potentiate angiogenic signaling, which is similar to our data showing that ANGPTL4 can synergistically increase FGF2-induced angiogenesis. Thus, ANGPTL4 may promote angiogenesis in ccRCC by potentiating other angiogenic signaling via interaction with ECSCR. To summarize, we demonstrated the pro-angiogenic potential of ANGPTL4 in ccRCC and its critical role in tumor development. Knockout or antibody-mediated inhibition of ANGPTL4 reduced tumor angiogenesis and growth and increased vessel normalization. This data supports the therapeutic potential of ANGPTL4 targeted treatment in ccRCC.

Citation Format: Zeng Jin, Umasankar De, Lei Wang, Jeremy Kleberg, Weizhou Zhang, Ryan Kolb. Angiopoietin-like 4 as a potential therapeutic target for clear cell renal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 571.

Co-targeting BCL-XL and MCL-1 with DT2216 and AZD8055 synergistically inhibit small-cell lung cancer growth without causing on-target toxicities in mice

Small-cell lung cancer (SCLC) is an aggressive malignancy with limited therapeutic options. The dismal prognosis in SCLC is in part associated with an upregulation of BCL-2 family anti-apoptotic proteins, including BCL-X_L and MCL-1. Unfortunately, the currently available inhibitors of BCL-2 family anti-apoptotic proteins, except BCL-2 inhibitors, are not clinically relevant because of various on-target toxicities. We, therefore, aimed to develop an effective and safe strategy targeting these anti-apoptotic proteins with DT2216 (our platelet-sparing BCL-X_L degrader) and AZD8055 (an mTOR inhibitor) to avoid associated on-target toxicities while synergistically optimizing tumor response. Through BH3 mimetic screening, we identified a subset of SCLC cell lines that is co-dependent on BCL-X_L and MCL-1. After screening inhibitors of selected tumorigenic pathways, we found that AZD8055 selectively downregulates MCL-1 in SCLC cells and its combination with DT2216 synergistically killed BCL-X_L/MCL-1 co-dependent SCLC cells, but not normal cells. Mechanistically, the combination caused BCL-X_L degradation and suppression of MCL-1 expression, and thus disrupted MCL-1 interaction with BIM leading to an enhanced apoptotic induction. In vivo, the DT2216 + AZD8055 combination significantly inhibited the growth of cell line-derived and patient-derived xenografts and reduced tumor burden accompanied by increased survival in a genetically engineered mouse model of SCLC without causing appreciable thrombocytopenia or other normal tissue injuries. Thus, these preclinical findings lay a strong foundation for future clinical studies to test DT2216 + mTOR inhibitor combinations in a subset of SCLC patients whose tumors are co-driven by BCL-X_L and MCL-1.

CD177 modulates the function and homeostasis of tumor-infiltrating regulatory T cells

Regulatory T (Treg) cells are one of the major immunosuppressive cell types in cancer and a potential target for immunotherapy, but targeting tumor-infiltrating (TI) Treg cells has been challenging. Here, using single-cell RNA sequencing of immune cells from renal clear cell carcinoma (ccRCC) patients, we identify two distinct transcriptional fates for TI Treg cells, Fate-1 and Fate-2. The Fate-1 signature is associated with a poorer prognosis in ccRCC and several other solid cancers. CD177, a cell surface protein normally expressed on neutrophil, is specifically expressed on Fate-1 TI Treg cells in several solid cancer types, but not on other TI or peripheral Treg cells. Mechanistically, blocking CD177 reduces the suppressive activity of Treg cells in vitro, while Treg-specific deletion of Cd177 leads to decreased tumor growth and reduced TI Treg frequency in mice. Our results thus uncover a functional CD177+ TI Treg population that may serve as a target for TI Treg-specific immunotherapy.

Proteolysis-targeting chimera against BCL-XL destroys tumor-infiltrating regulatory T cells

Regulatory T cells (Tregs) play an important role in maintaining immune homeostasis and, within tumors, their upregulation is common and promotes an immunosuppressive microenvironment. Therapeutic strategies that can eliminate Tregs in the tumor (i.e., therapies that do not run the risk of affecting normal tissues), are urgently needed for the development of cancer immunotherapies. Here we report our discovery of B-cell lymphoma extra-large (BCL-X_L) as a potential molecular target of tumor-infiltrating (TI) Tregs. We show that pharmacological degradation of BCL-X_L using a newly developed platelet-sparing BCL-X_L Proteolysis-targeting chimera (PROTAC) induces the apoptosis of TI-Tregs and the activation of TI-CD8⁺ T cells. Moreover, these activities result in an effective suppression of syngeneic tumor growth in immunocompetent, but not in immunodeficient or CD8⁺ T cell-depleted mice. Notably, treatment with BCL-X_L PROTAC does not cause detectable damage within several normal tissues or thrombocytopenia. These findings identify BCL-X_L as a target in the elimination of TI-Tregs as a component of cancer immunotherapies, and that the BCL-X_L-specific PROTAC has the potential to be developed as a therapeutic for cancer immunotherapy.

Targeting regulatory T cells (Treg) represents a therapeutic option to abrogate tumor-associated immune suppression. Here the authors show that pharmacological degradation of BCL-X_L preferentially induces apoptosis of tumor-infiltrating Treg, promoting CD8 T cell activation and anti-tumor immune responses in preclinical cancer models.

Plumbagin from a tropical pitcher plant (Nepenthes alata Blanco) induces apoptotic cell death via a p53-dependent pathway in MCF-7 human breast cancer cells

Plumbagin (5-hydroxy-2-methyl-1,4-naphthaquinone) has displayed antitumor activity in vitro and in animal models; however, the underlying molecular mechanisms have not been fully explored. The aim of this study was to investigate the anticancer effects of plumbagin isolated from Nepenthes alata against MCF-7 breast cancer cells. We examined the cytotoxicity, cell cycle regulation, apoptotic cell death, and generation of intracellular reactive oxygen species (ROS) in MCF-7 cells. Plumbagin exhibited potent cytotoxicity in MCF-7 cells (wild-type p53) compared to that in SK-OV-3 (null-type) human epithelial ovarian cancer cells. Specifically, plumbagin upregulated the expression of p21^CIP1/WAF1 in MCF-7 cells, causing cell cycle arrest in the G2/M phase through inhibition of cyclin B1 levels. Plumbagin also significantly increased the ratio of Bax/Bcl-2 and release of cytochrome c, resulting in apoptotic cell death in MCF-7 cells. Furthermore, plumbagin dramatically increased the intracellular ROS level, whereas pretreatment with the ROS scavenger N-acetyl cysteine protected against plumbagin-induced cytotoxicity, suggesting that ROS formation plays a pivotal role in antitumor activity in MCF-7 cells. In mice bearing MCF-7 cell xenografts, plumbagin significantly reduced tumor growth and weight without apparent side effects. We therefore concluded that plumbagin exerts anticancer activity against MCF-7 cells through the generation of intracellular ROS, resulting in the induction of apoptosis via a p53-dependent pathway. This study thus identifies a new anticancer mechanism of plumbagin against p53-dependent breast cancer cells and suggests a novel strategy for overcoming of breast cancer therapy.

Novel therapeutic roles of MC-4 in combination with everolimus against advanced renal cell carcinoma by dual targeting of Akt/pyruvate kinase muscle isozyme M2 and mechanistic target of rapamycin complex 1 pathways

Current clinical trials of new anticancer therapies against metastatic renal cell carcinoma (RCC), including molecular-targeted therapies, have not shown promise. The purpose of this study was to preclinically assess the antitumor effects of MC-4, a partially purified material of Artemisia annua L., as a monotherapy or in combination with the known mechanistic target of rapamycin complex 1 (mTORC1) inhibitor, everolimus, against Caki-1 (Von Hippel-Lindau (VHL)+/+) and 786-O (VHL-/-) human RCC cells. MC-4 monotherapy significantly increased tumor growth inhibition and autophagic cell death in RCC cells in vitro and in vivo. Everolimus led to compensatory Akt activation by inhibiting only mTORC1 signaling pathway. In contrast to everolimus, MC-4 enhanced phosphatase and tensin homolog expression and reduced its downstream effector, Akt/pyruvate kinase muscle isozyme M2 (PKM2), leading to decreased expression of glucose transporter 1, which is associated with cancer cell metabolism. The synergistic antitumor and anti-metastatic effects induced by co-administration of MC-4 and everolimus involve cell growth inhibition and autophagic cell death via dual targeting of phosphatidylinositol 3-kinase (PI3K)/Akt/PKM2 and mTORC1. These findings suggest that MC-4 is a novel Akt/PKM2 inhibitor that can overcome the limitation of existing mTOR inhibitors and can be considered a novel strategy to treat patients with rapidly progressing advanced RCC.

A New Synthetic Histone Deacetylase Inhibitor, MHY2256, Induces Apoptosis and Autophagy Cell Death in Endometrial Cancer Cells via p53 Acetylation

We previously discovered a novel sirtuin (SIRT) inhibitor, MHY2256, that exerts anticancer activity through p53 acetylation in MCF-7 human breast cancer cells. We investigated the anticancer activity of MHY2256 against hormone-related cancer, an endometrial cancer with a poor prognosis. The IC₅₀ values of MHY2256 were shown to be much lower than those of salermide, a well-known SIRT inhibitor. Furthermore, MHY2256 significantly reduced the protein expression and activities of SIRT1, 2, and 3, with similar effects to salermide. Particularly, MHY2256 markedly inhibited tumor growth in a tumor xenograft mouse model of Ishikawa cancer cells. During the experimental period, there was no significant change in the body weight of mice treated with MHY2256. A detailed analysis of the sensitization mechanisms of Ishikawa cells revealed that late apoptosis was largely increased by MHY2256. Additionally, MHY2256 increased G1 arrest and reduced the number of cell cyclic-related proteins, suggesting that apoptosis by MHY2256 was achieved by cellular arrest. Particularly, p21 was greatly increased by MHY225656, suggesting that cell cycle arrest by p21 is a major factor in MHY2256 sensitization in Ishikawa cells. We also detected a significant increase in acetylated p53, a target protein of SIRT1, in Ishikawa cells after MHY2256 treatment. In a mouse xenograft model, MHY2256 significantly reduced tumor growth and weight without apparent side effects. These results suggest that MHY2256 exerts its anticancer activity through p53 acetylation in endometrial cancer and can be used for targeting hormone-related cancers.

Alkyl chain-modified cyclometalated iridium complexes as tunable anticancer and imaging agents

Imidazole-based cyclometalated iridium complexes [1]⁺–[5]⁺ have been developed displaying alkyl chain length dependent anticancer activity and imaging property.

Rhodium-Catalyzed [3 + 2] Annulation of Cyclic N-Acyl Ketimines with Activated Olefins: Anticancer Activity of Spiroisoindolinones

The rhodium(III)-catalyzed redox-neutral coupling reaction of N-acyl ketimines generated in situ from 3-hydroxyisoindolinones with various activated olefins is described. This approach leads to the synthesis of bioactive spiroisoindolinone derivatives in moderate to high yields. In the case of internal olefins such as maleimides, maleates, fumarates, and cinnamates, spiroindanes were obtained by the [3 + 2] annulations reaction. In sharp contrast, acrylates and quinones displayed the β-H elimination followed by Prins-type cyclization furnishing spiroindenes. The synthetic compounds were evaluated for in vitro anticancer activity against androgen-sensitive human prostate adenocarcinoma cells (LNCaP), human prostate adenocarcinoma cells (DU145), human endometrial adenocarcinoma cells (Ishikawa), human breast cancer cell (MCF-7), and triple negative human breast cancer cells (MDA-MB-231). Notably, quinone-containing spiroindenes displayed potent anticancer activity about 2- to 3-fold stronger than that of anticancer agent doxorubicin.

Anticancer Effects of a New SIRT Inhibitor, MHY2256, against Human Breast Cancer MCF-7 Cells via Regulation of MDM2-p53 Binding

The sirtuins (SIRTs), a family of NAD⁺-dependent class III histone deacetylase, are involved in various biological processes including cell survival, division, senescence, and metabolism via activation of the stress-response pathway. Recently, inhibition of SIRTs has been considered a promising anticancer strategy, but their precise mechanisms of action are not well understood. In particular, the relevance of p53 to SIRT-induced effects has not been fully elucidated. We investigated the anticancer effects of a novel SIRT inhibitor, MHY2256, and its efficacy was compared to that of salermide in MCF-7 (wild-type p53) and SKOV-3 (null-type p53) cells. Cell viability, SIRT1 enzyme activity, cell cycle regulation, apoptosis, and autophagic cell death were measured. We compared sensitivity to cytotoxicity in MCF-7 and SKOV-3 cells. MHY2256 significantly decreased the viability of MCF-7 (IC₅₀, 4.8 μM) and SKOV-3 (IC₅₀, 5.6 μM) cells after a 48 h treatment period. MHY2256 showed potent inhibition (IC₅₀, 0.27 mM) against SIRT1 enzyme activity compared with nicotinamide (IC_50, >1 mM). Moreover, expression of SIRT (1, 2, or 3) protein levels was significantly reduced by MHY2256 treatment in both MCF-7 and SKOV-3 cells. Flow cytometry analysis revealed that MHY2256 significantly induced cell cycle arrest in the G1 phase, leading to an effective increase in apoptotic cell death in MCF-7 and SKOV-3 cells. A significant increase in acetylated p53, a target protein of SIRT, was observed in MCF-7 cells after MHY2256 treatment. MHY2256 up-regulated LC3-II and induced autophagic cell death in MCF-7 cells. Furthermore, MHY2256 markedly inhibited tumor growth in a tumor xenograft model of MCF-7 cells. These results suggest that a new SIRT inhibitor, MHY2256, has anticancer activity through p53 acetylation in MCF-7 human breast cancer cells.

Synthesis of Succinimide-Containing Chromones, Naphthoquinones, and Xanthones under Rh(III) Catalysis: Evaluation of Anticancer Activity

The weakly coordinating ketone group directed C-H functionalizations of chromones, 1,4-naphthoquinones, and xanthones with various maleimides under rhodium(III) catalysis are described. These protocols efficiently provide a range of succinimide-containing chromones, naphthoquinones, and xanthones with excellent site selectivity and functional group compatibility. All synthetic compounds were screened for in vitro anticancer activity against human breast adenocarcinoma cell lines (MCF-7). In particular, compounds 7aa and 7ca with a naphthoquinone scaffold were found to be highly cytotoxic, with an activity competitive with anticancer agent doxorubicin.

Abstract 2984: Plumbagin induces p53-dependent apoptosis via generation of reactive oxygen species in human cancer cells

Plumbagin [5-hydroxy-2-methyl-1,4-naphthaquinone], a major constituent derived from Drosera and Plumbago, displays antitumor activity both in vitro and animal models, but the molecular mechanisms of p53-mediated antitumor effects have not been clearly explored. The aim of this study is to determine the anticancer effects of plumbagin on MCF-7 (wild type p53) or Ishikawa (p53-mutant type) cells. We compared the cytotoxicity, cell cycle regulation, apoptotic cell death, and generation of intracellular reactive oxygen species (ROS) in these cancer cells. Plumbagin inhibits the growth of Ishikawa (endometrial cancer cells) and SKOV-3 cells, particularly MCF-7 cells. Plumbagin significantly increased the expression of p53 and reduced Murine Double Minute 2 (MDM2) in the MCF-7 cells. Plumbagin up-regulated the expression of p21(CIP1/WAF1) causing cell cycle arrest in the G2/M-phase by down-regulating cyclin B1 and Cdc2 in MCF-7 as well as Ishikawa cells. Plumbagin altered the ratio of Bax/Bcl-2 and cytochrome c released resulting apoptotic cell death in MCF-7 cells. Furthermore, plumbagin dramatically increased the intracellular ROS level, and pretreatment with the ROS scavenger, N-acetyl cysteine (NAC), protected against growth inhibition by plumbagin, suggesting that ROS play a pivotal role in the antitumor activity in MCF-7 cells. In mice bearing the MCF-7 cell xenografts, plumbagin significantly reduced the tumor growth and weight, without apparent side effects. In conclusion, plumbagin exerted anticancer activity in MCF-7 by generation of intracellular ROS that causes induction of apoptosis via Bcl-2/Bax pathways as well as cell cycle arrest.

KEYWORDS: Plumbagin; breast cancer; apoptosis; p53, reactive oxygen species

Citation Format: Umasankar De, Amit Kundu, Eunbin Kim, Jonghwan Kwack, Hyungsik Kim. Plumbagin induces p53-dependent apoptosis via generation of reactive oxygen species in human cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2984.

Cyclometallated iridium complexes inducing paraptotic cell death like natural products: synthesis, structure and mechanistic aspects

Mononuclear cyclometallated iridium complexes of polypyridyl-phenazine based ligands have been synthesized and characterized which display excellent anticancer activity through paraptosis.

A New Histone Deacetylase Inhibitor, MHY219, Inhibits the Migration of Human Prostate Cancer Cells via HDAC1

Histone deacetylase (HDAC) inhibitors are considered novel agents for cancer chemotherapy. We previously investigated MHY219, a new HDAC inhibitor, and its potent anticancer activity in human prostate cancer cells. In the present study, we evaluated MHY219 molecular mechanisms involved in the regulation of prostate cancer cell migration. Similar to suberanilohydroxamic acid (SAHA), MHY219 inhibited HDAC1 enzyme activity in a dose-dependent manner. MHY219 cytotoxicity was higher in LNCaP (IC₅₀=0.67 μM) than in DU145 cells (IC₅₀=1.10 μM) and PC3 cells (IC₅₀=5.60 μM) after 48 h of treatment. MHY219 significantly inhibited the HDAC1 protein levels in LNCaP and DU145 cells at high concentrations. However, inhibitory effects of MHY219 on HDAC proteins levels varied based on the cell type. MHY219 significantly inhibited LNCaP and DU145 cells migration by down-regulation of matrix metalloprotease-1 (MMP-1) and MMP-2 and induction of tissue inhibitor of metalloproteinases-1 (TIMP-1). These results suggest that MHY219 may potentially be used as an anticancer agent to block cancer cell migration through the repression of MMP-1 and MMP-2, which is related to the reduction of HDAC1.

Dinuclear [{(p-cym)RuCl}2(μ-phpy)](PF6)2 and heterodinuclear [(ppy)2Ir(μ-phpy)Ru(p-cym)Cl](PF6)2 complexes: synthesis, structure and anticancer activity

Heterodinuclear Ir–Ru (2) with polypyridyl based phpy ligand shows autophagy induced cell death, whereas homodinuclear Ru–Ru (1) is inactive.

A novel anthracene derivative, MHY412, induces apoptosis in doxorubicin-resistant MCF-7/Adr human breast cancer cells through cell cycle arrest and downregulation of P-glycoprotein expression

New potential chemotherapeutic strategies are required to overcome multidrug resistance (MDR) in cancer. This study investigated the anticancer effect of a novel anthracene derivative MHY412 on doxorubicin-resistant human breast cancer (MCF-7/Adr) cells. We measured cell viability and the expression of apoptosis-related genes; in addition, the antitumor activity of MHY412 was confirmed using an in vivo tumor xenograft model. MHY412 significantly inhibited the proliferation of MCF-7/Adr and MCF-7 cells in a concentration-dependent manner. Notably, the half-maximal inhibitory concentration (IC50) values of MHY412 in MCF-7/Adr (0.15 µM) and MCF-7 (0.26 µM) cells were lower than those of doxorubicin (MCF-7/Adr, 13.6 µM and MCF-7, 1.26 µM) after treatment for 48 h. MHY412 at low concentrations induced S phase arrest, but at high concentrations, the number of MCF-7/Adr cells in the sub-G1 phase significantly increased. MHY412-induced sub-G1 phase arrest was associated with inhibition of cyclin, cyclin-dependent kinase 2 (CDK2) and p21 expression in MCF-7/Adr cells. MHY412 markedly reduced P-glycoprotein (P-gp) expression and increased apoptotic cell death in MCF-7/Adr cells. Cleavage of poly-ADP ribose polymerase, reduced Bcl-2 expression, and increased in cytochrome c release in MCF-7/Adr cells confirmed the above results. In addition, MHY412 markedly inhibited tumor growth in a tumor xenograft model of MCF-7/Adr cells. Our data suggest that MHY412 exerts antitumor effects by selectively modulating the genes related to cell cycle arrest and apoptosis. In particular, MHY412 is a new candidate agent for the treatment of Bcl-2 overexpressed doxorubicin-resistant human breast cancer.

A novel histone deacetylase (HDAC) inhibitor MHY219 induces apoptosis via up-regulation of androgen receptor expression in human prostate cancer cells

Histone deacetylase (HDAC) inhibitors are a new class of anticancer agents that act by inhibiting cancer cell proliferation and inducing apoptosis in various cancer cell lines. To investigate the anticancer effect of a novel histone deacetylase (HDAC) inhibitor MHY219, its efficacy was compared to that of suberoylanilide hydroxamic acid (SAHA) in human prostate cancer cells. The anticancer effects of MHY219 on cell viability, HDAC enzyme activity, cell cycle regulation, apoptosis and other biological assays were performed. MHY219 was shown to enhance the cytotoxicity on DU145 cells (IC₅₀, 0.36 μM) when compared with LNCaP (IC₅₀, 0.97 μM) and PC3 cells (IC₅₀, 5.12 μM). MHY219 showed a potent inhibition of total HDAC activity when compared with SAHA. MHY219 increased histone H3 hyperacetylation and reduced the expression of class I HDACs (1, 2 and 3) in prostate cancer cells. MHY219 effectively increased the sub-G1 fraction of cells through p21 and p27 dependent pathways in DU145 cells. MHY219 significantly induced a G2/M phase arrest in DU145 and PC3 cells and arrested the cell cycle at G0/G1 phase in LNCaP cells. Furthermore, MHY219 effectively increased apoptosis in DU145 and LNCaP cells, but not PC3 cells, according to Annexin V/PI staining and Western blot analysis. These results indicate that MHY219 is a potent HDAC inhibitor that targets regulating multiple aspects of cancer cell death and might have preclinical value in human prostate cancer chemotherapy, warranting further investigation.

Type VI choledochal cyst revisited

Choledochal cysts are rare cystic dilatations of the bile ducts, which are commonly found in children. Choledochal cysts in adults are uncommon, and cystic dilatation of the cystic duct (type VI choledochal cyst) is a unique occurrence. To date, specific pathogenic and diagnostic criteria for describing type VI cysts have been lacking. This report attempts to lay down the specific diagnostic and management criteria of this uncommon entity, with reviews of all available cases reported in the literature.

Volvulus of the sigmoid colon

AIMS

The current status of sigmoid volvulus (SV) was reviewed to assess trends in management and to assess the literature.

METHOD

The literature on SV was retrieved using PubMed, Embase, Scopus, Pakmedinet, African Journals online (AJOL), Indmed and Google scholar. These databases were searched for text words including 'sigmoid', 'colon' and 'volvulus'. Relevant nonindexed surgical journals published from endemic countries were also manually searched. We focused on original articles published within the last 10 years; but classical references prior to this period were also included. Seminal papers published in non-English languages were also included.

RESULTS

Sigmoid volvulus is a leading cause of acute colonic obstruction in South America, Africa, Eastern Europe and Asia. It is rare in developed countries such as USA, UK, Japan and Australia. Characteristic geographic variations in the incidence, clinical features, prognosis and comorbidity of SV justify recognition of endemic and sporadic subtypes. Controversy on aetiologic agents can be minimized by classifying them into 'predisposing' and 'precipitating' factors. Modern imaging systems, although more effective than plain radiographs, are yet to gain popularity. Emergency endoscopic reduction is the treatment of choice in uncomplicated patients. But it is only a temporizing procedure, and it should be followed in most cases by elective definitive surgery. Resection of the redundant sigmoid colon is the gold standard operation. The role of newer nonresective alternatives is yet to be ascertained. Although emergency resection with primary anastomosis (ERPA) has been controversial in the past, it is now increasingly accepted as a safe option with superior results. Management in elderly debilitated patients is extremely difficult. Paediatric SV significantly differs from that in adults. SV is frequently associated with neuropsychiatric diseases, diabetes mellitus and Chagas disease. The overall mortality in recent studies is < 5%.

CONCLUSION

There are almost no randomised controlled studies. According to the grading system of Oxford Center for Evidence Based Medicine (CEVM), available published evidence is at level 4. The recommendations resulting form this review are of 'C' grade.

Recurrent pyogenic cholangitis

A 26-year-old male presented with jaundice and recurrent cholangitis. Ultrasonography revealed dilated intra- and extrahepatic biliary tree packed with multiple calculi. Endoscopic retrograde cholangiopancreatography and computerised tomography scan confirmed the findings and a diagnosis of recurrent pyogenic cholangitis was made. Cholecystectomy, choledocholithotomy with removal of stones and Roux-en-Y choledochojejunostomy were performed.