Triamcinolone acetonide modulates TGF­ß2­induced angiogenic and tissue­remodeling effects in cultured human retinal pigment epithelial cells.

Transforming growth factor­ß2 (TGF­ß2) has been implicated in the pathogenesis of proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR), due to its ability to stimulate the overproduction of pro­angiogenic factors, such as vascular endothelial growth factor (VEGF), and remodeling of the extracellular matrix (ECM). Although intravitreal triamcinolone acetonide (TA) is clinically useful in the treatment of PVR and PDR, its molecular mechanism has yet to be fully elucidated. The present study investigated whether TA treatment altered TGF­ß2­driven biological effects on the behavior of cultured human retinal pigment epithelial (RPE) cells, in order to determine which signaling pathway may be essential for the pharmacological action of TA. The R­50 human RPE cell line was treated with TA in the presence of TGF­ß2, followed by analyses of cell viability and contraction using cell viability and collagen gel contraction assays. VEGF mRNA expression and protein production were measured using reverse transcription­quantitative PCR and ELISA, respectively. The phosphorylation status of signaling mediators and the protein expression of type I collagen (COL1A1), α­smooth muscle actin (α­SMA), and ECM­remodeling enzymes, including MMP­2 and MMP­9, were analyzed using western blotting. The gelatinolytic activity of MMPs was detected using gelatin zymography. TA treatment exhibited no prominent cytotoxicity but markedly antagonized TGF­ß2­induced cytostatic effects on RPE cell viability and TGF­ß2­enhanced contractility in collagen gels. In the context of TGF­ß2­related signaling, TA significantly attenuated TGF­ß2­elicited Smad2, extracellular­regulated kinase (ERK)1/2 and p38 mitogen­activated protein kinase (MAPK) phosphorylation. Moreover, TA markedly mitigated TGF­ß2­induced VEGF upregulation through ablation of p38 signaling activity. TA also partially attenuated TGF­ß2­elicted expression of COL1A1, α­SMA, MMP­2, and MMP­9, but only suppressed TGF­ß2­induced MMP­9 gelatinolytic activity. Mechanistically, the MEK/ERK signaling pathway may have a critical role in the TGF­ß2­induced upregulation of COL1A1, α­SMA and MMP­9. In conclusion, TA may be considered a useful therapeutic agent for treating TGF­ß2­associated intraocular angiogenesis and tissue remodeling, the underlying mechanism of which may involve the ERK and p38 MAPK signaling pathways.

High mobility group B1 up-regulates angiogenic and fibrogenic factors in human retinal pigment epithelial ARPE-19 cells.

Hypoxia-induced retinal neovascularization plays a central role in the pathogenesis of diabetic retinopathy. This study aimed to investigate whether hypoxia leads to the release of nuclear high mobility group box 1 (HMGB1) peptides from cultured retinal pigment epithelial ARPE-19 cells, to determine the effect of HMGB1 on angiogenic cytokine production and elucidate the involved signaling pathways. A chemical hypoxia mimetic agent, cobalt chloride, induced SIRT1 downregulation, HMGB1 nucleocytoplasmic relocation and extracellular release from ARPE-19 cells, implicating its autocrine function. Resveratrol treatment significantly reduced secretion of HMGB1 from ARPE-19 cells exposed to hypoxia. Cell proliferation and cell cycle analyses demonstrated that exogenous HMGB1 caused significant growth suppression and G1 cell cycle arrest in ARPE-19 cells. Morphological observations showed that HMGB1 enhanced adhesion, but suppressed migration of ARPE-19 cells. More intriguingly, HMGB1 up-regulated expression of angiofibrogenic factors in ARPE-19 cells, including VEGF, bFGF, TGF-ß2, and CTGF. Signal profiling characterization indicated that HMGB1 triggered hyperphosphorylation of Akt, p38 MAPK, and NF-κB, but not that of ERK, JNK, and Smad2, whereas inhibition of PI3K, MAPK, or NF-κB significantly attenuated the HMGB1-driven cytokine overproduction in ARPE-19 cells. Functional neutralization with anti-TLR4 and -RAGE antibodies confirmed that both receptors were involved in the cytokine overproduction. In conclusion, chemically-mimicked hypoxia induced nucleocytoplasmic relocation and release of HMGB1 peptides, which in turn up-regulated the production of angiofibrogenic factors in RPE cells, thereby contributing to the pathogenesis of hypoxia-associated diabetic retinopathies. Conversely, blockades of intraocular HMGB1 bioavailability or signal activation may prevent angiofibrogenesis in development of diabetic retinopathy.

All-trans retinoic acid suppresses the adhering ability of ARPE-19 cells via mitogen-activated protein kinase and focal adhesion kinase.

This study investigated the signaling mechanism underlying the anti-adhesive effect of all-trans retinoic acid (ATRA) on retinal pigment epithelial ARPE-19 cells. Adhesion kinetics with or without ATRA treatment were profiled by adhesion assay. Surface coating with type IV collagen, fibronectin, laminin, but not type I collagen, significantly enhanced adhesion and spreading of ARPE-19 cells, while ATRA at subtoxic doses (ranging from 10-7 to 10-6 M) profoundly suppressed the extracellular matrix-enhanced adhesion ability. Cell attachment on FN activated PI3K/Akt and MAPK cascades, whereas ATRA pretreatment blunted the early phosphorylation of Akt and MAPK signaling mediators including p38 MAPK, JNK1/2, and ERK1/2. Mechanistically, signaling blockade with selective kinase inhibitors demonstrated that all MAPK pathways were involved in the anti-adhesive effect of ATRA, whereas the PI3K inhibitor treatment significantly potentiated the ATRA-suppressed RPE cell adhesion. Moreover, ATRA treatment did not affect intracellular F-actin distribution, but remarkably reduced focal adhesion kinase (FAK) expression and its nuclear localization during ARPE-19 cell attachment. In conclusion, ATRA suppresses the adhering ability of ARPE-19 cells at least in part through MAPK and FAK pathways. Signaling blockade with PI3K inhibitor could be regarded as an alternative modality for treating proliferative vitreoretinopathy.

Propofol-enhanced autophagy increases motility and angiogenic capacity of cultured human umbilical vascular endothelial cells.

AIMS: Propofol (PPF), an intravenous anesthetic agent, is previously reported to attenuate oxidative stress- and inflammation-induced endothelial cell dysfunction. This study investigated its effect on endothelial cell biology. MAIN METHODS: Cultured human umbilical vein endothelial cells (HUVECs) were treated with PPF and subject to measurements for nitric oxide (NO) production, autophagy flux, signal transduction, migration, and in vitro angiogenesis. KEY FINDINGS: Non-cytotoxic PPF treatment was found to significantly upregulate inducible nitric oxide synthase (NOS2) but downregulate constitutive NOS3 expression. It also potentiated LPS-induced ICAM-1 overexpression and NO overproduction. Mechanistically, the PPF-activated signal transduction in PI3K/Akt, ERK1/2, p38 MAPK, and JNK pathways were involved in the PPF-driven NO overproduction. PPF exhibited a stimulatory effect on autophagy flux by increasing expression of autophagy markers including mTOR, Beclin-1, Atg5, and LC3I/II, as well as a late endosomal indicator, Rab7. However, PPF appeared to antagonize the Rab7 upregulation by LPS. Functionally, PPF enhanced in vitro migratory and angiogenic capacities of HUVECs, but this enhancement was drastically abrogated by the presence of autophagy inhibitors, indicating a pro-angiogenic contribution of PPF-enhanced autophagy in cultured HUVECs. SIGNIFICANCE: Our findings support the notion that PPF enhances motility and angiogenic capacity of cultured HUVECs through an autophagy-involved regulatory mechanism.

Toll-like receptor-4 is a target for suppression of proliferation and chemoresistance in HepG2 hepatoblastoma cells.

Toll-like receptor-4 (TLR4) is known to influence growth and migration of hepatocellular tumors; however, its role in hepatoblastoma remains poorly understood. This study investigated the regulatory role of TLR4 in proliferation and chemoresistance of HepG2 hepatoblastoma cells. Treatment with lipopolysaccharide (LPS), a TLR4 agonist, was found to significantly upregulate TLR4 expression in HepG2 cells, but not in malignant Huh-7 and Sk-Hep1 hepatocellular carcinoma cells. Additionally, IL-6 enhanced LPS-induced TLR4 upregulation. LPS-stimulated TLR4 activation increased proliferation, nitric oxide synthase (NOS) expression, and NO production in HepG2 cells. Chemotherapeutic agents, cisplatin and doxorubicin, effectively inhibited TLR4 expression in HepG2 cells. Characterization of LPS-induced signaling activation and blockade with kinase inhibitors revealed the involvement of Akt and MAPK pathways in LPS-enhanced NO release from, and proliferation of HepG2 cells. Mechanistically, gene modifications as a result of TLR4 transfection and siRNA-mediated knockdown further demonstrated a crucial role for TLR4 in the regulation of NOS expression, cell proliferation, and chemoresistance in HepG2 cells. These findings suggest that targeting TLR4 expression and its cognate signaling may modulate proliferation and chemosensitivity in hepatoblastoma cells and serve as a potential therapeutic target.

Methylglyoxal, a reactive glucose metabolite, enhances autophagy flux and suppresses proliferation of human retinal pigment epithelial ARPE-19 cells.

Methylglyoxal (MGO), a glycolytic metabolite, induces oxidative injury and apoptotic cell death that play a pathogenetic role in age-related macular degeneration (AMD). This study examined the impact of MGO on cell proliferation and autophagy flux in retinal pigment epithelium (RPE) ARPE-19 cells and elucidated the underlying mechanism. Short-term MGO exposure suppressed cell proliferation without induction of apoptotic cell death, increased production of reactive oxygen species, and potentiated H2O2-exhibited cytotoxicity in ARPE-19 cells. Conversely, pretreatment with N-acetylcysteine, a ROS scavenger, and aminoguanidine, an MGO blocker, prevented MGO-induced growth retardation. MGO significantly enhanced autophagy flux and increased intracellular accumulation of autophagosomes, which was functionally confirmed by addition of autophagy enhancer or inhibitors. Signaling kinetic observation indicated that MGO remarkably triggered phosphorylation of Akt, ERK1/2, p38 MAPK, and JNK1/2. Blockade of kinase activity demonstrated that the hyperphosphorylation of Akt, ERK1/2, JNK, and p38 MAPK were all involved in the MGO-enhanced autophagy and growth-arresting effect in ARPE-19 cells. Moreover, pretreatment with autophagic flux inhibitors including 3-methyladenine, bafilomycin A, and chloroquine effectively ameliorated MGO- but not H2O2-mediated ARPE-19 cytotoxicity. In conclusion, modulation of autophagy flux activity by using autophagic or kinase inhibitors may be an applicable modality to treat AMD.

[A pilot study of the professional autonomy, job satisfaction, and related factors of nurses at a regional hospital].

BACKGROUND: Professional autonomy often causes confusion in nursing staffs that limit their ability to perform to the best of their professional capabilities. Moreover, heavy and busy workloads reduce the energy available for work resulting in lower working efficiency and lower job satisfaction. PURPOSE: This study explores the status and factors related to professional autonomy and job satisfaction in nurses. METHODS: A cross-sectional design was used to target the nurses employed at a regional hospital in southern Taiwan. Data on locus of control, professional autonomy, and job satisfaction were collected for analysis. RESULTS: Data were collected from 207 nurses, with 196 valid responses (response rate: 94.69%). One hundred and forty-six subjects (74.5%) were found to have an internal locus of control personality type. Scores for both professional autonomy and job satisfaction were above the "moderate" level (averages: 3.37 and 3.32, respectively, on a maximum scale of 5). Social demographic differences contributed to the variance in professional autonomy and job satisfaction among participants. Professional autonomy was found to be positively associated with job satisfaction. CONCLUSIONS: The findings of this study indicate that nurses with an internal locus of control personality exhibit higher professional autonomy and job satisfaction and that higher professional autonomy is associated with higher job satisfaction.

Pharmacological implications from the adhesion-induced signaling profiles in cultured human retinal pigment epithelial cells.

Extracellular matrix (ECM) plays an active and complex role in regulating cellular behaviors, including proliferation and adhesion. This study aimed at delineating the adhesion-induced signaling profiles in cultured human retinal pigment epithelium (RPE) cells and investigating the antiadhesion effect of antiproliferative drugs in this context. RPE R-50 cells grown on various ECM molecules, such as type I and IV collagens, fibronectin, and laminin, were used for adhesion assay and for examining the phosphorylation profiles of signaling mediators including Akt, extracellular signal-regulated kinase (ERK) 1/2, and integrin-linked kinase (ILK) using Western blotting. The cells receiving antiproliferative drug treatment at subtoxic doses were used to evaluate their antiadhesive and suppressive effects on kinase activities. ECM coating enhanced adhesion and spreading of RPE cells significantly. The cellular attachment onto ECM-coated surfaces differentially induced Akt, ERK1/2, and ILK phosphorylation, and concomitantly increased p53 phosphorylation and cyclin D1 expression, but decreased Bcl-2/Bax ratios. Treatment with antiproliferative agents, including 5-fluorouracil, mitomycin C, and daunomycin, at subtoxic doses suppressed the ability of RPE cells to adhere to ECM substratum significantly. This suppression was in part mediated through reduction of integrin ß1 and ß3 expressions and interfering Akt-ILK signaling activity. Mechanistically, blockade of PI3K/Akt signaling resulted in the suppressed adhesion of RPE cells to ECM. These findings support the hypothesis that, in addition to their antimitogenic effect, antiproliferative agents also exhibit suppressive effect on the adhesiveness of cultured RPE cells. Moreover, inhibitors of the PI3K/Akt signaling mediator can potentially be used as therapeutic agents for proliferative vitreoretinopathy.

Simvastatin attenuates the additive effects of TNF-α and IL-18 on the connexin 43 up-regulation and over-proliferation of cultured aortic smooth muscle cells.

Statin therapy is known to down-regulate inflammatory activities in atheromatous tissues of animals. The aims of this study were to examine the regulatory role of interleukin-18 (IL-18) in the connexin 43 (Cx43) and the proliferation of cultured aortic smooth muscle cells (SMCs) as well as to elucidate the underlying therapeutic mechanism of simvastatin. Vytorin therapy significantly alleviated high-cholesterol diet-induced hypercholesterolemia, suppressed neointimal hyperplasia, macrophage infiltration, and Cx43 and IL-18 expression in rabbit aortic walls. In vitro study using an aortic SMC line showed that IL-18 up-regulated constitutive Cx43 expression and potentiated tumor necrosis factor-α (TNF-α)-triggered Akt and MAPK signaling pathways. Simvastatin treatment alone reduced constitutive Cx43 levels and prevented the TNF-α-induced IL-18 up-regulation. Mechanistic investigation using kinase-specific inhibitors showed that simvastatin pretreatment attenuated TNF-α-elicited Akt and ERK1/2 phosphorylation, whereas PI3K and all MAPK activities were also implied in the additive effect of TNF-α and IL-18 on Cx43 up-regulation. Proliferation assay indicated that IL-18 stimulated SMC proliferation and synergized the TNF-α-stimulated cell proliferation. Likewise, simvastatin treatment suppressed the SMC over-proliferation induced not only by TNF-α alone, but also by simultaneous treatment with TNF-α and IL-18. The suppression of simvastatin in SMC proliferation was not mediated through mitochondrial related pro-apoptogenesis under both scenarios. In conclusion, simvastatin attenuates the additive effects of TNF-α and IL-18 on Cx43 up-regulation and over-proliferation of aortic SMCs, mainly through the blockade of Akt signaling pathway. These findings may fortify the rationale underlying the atheroprotective mechanism of statin therapy.

Pleiotropic role of atorvastatin in regulation of human retinal pigment epithelial cell behaviors in vitro.

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, possess pleiotropic effects that have been extended to modulation of various cellular behaviors. This study aimed at examining whether atorvastatin (AVN) modulates cell growth, adhesion, migration, and contraction of cultured human retinal pigment epithelium (RPE) cells. The in vitro effects of AVN on human RPE cells was analyzed in terms of cell proliferation, cell cycle, cell adhesion, migration, and contraction assays. The modulatory effect of AVN on TGF-ß2-triggered signaling was determined by Western blotting detection. AVN at submicromolar dose exhibited no prominent morphological alteration and cytotoxicity, whereas it elicited cytostatic effect at concentrations higher than 1 µM. Cell cycle analysis showed that AVN induced growth arrest in both G1 and G2/M phases. AVN at 1 µM or higher concentrations significantly suppressed RPE cell adhesion. Cell migration and 3D collagen contraction assays showed that AVN significantly suppressed RPE cell migration and contractility, respectively. Mechanistically, AVN treatment transiently up-regulated phosphorylation of Akt, ERK1/2, and p38 MAPK, whereas down-regulated that of JNK1. Intriguingly, AVN pretreatment prominently attenuated the TGF-ß(2)-mediated non-Smad signaling, including Akt, ERK1/2, p38 MAPK, and JNK1 phosphorylation. Besides, it directly reduced constitutive level of myosin regulatory light chain peptide MYL9 and mitigated the TGF-ß(2)-induced phosphorylation of myosin phosphatase-targeting subunit 1, MYPT1. These in vitro findings strongly suggest that AVN possesses pleiotropic function on RPE cells, including anti-proliferation, anti-adhesion, anti-migration as well as anti-contraction. In conclusion, AVN treatment may be considered a useful therapy for proliferative vitreoretinal diseases.

A DC-81-indole conjugate agent suppresses melanoma A375 cell migration partially via interrupting VEGF production and stromal cell-derived factor-1α-mediated signaling.

Pyrrolo[2,1-c][1,4]benzodiazepine (PBD) chemicals are antitumor antibiotics inhibiting nucleic acid synthesis. An indole carboxylate-PBD hybrid with six-carbon spacer structure (IN6CPBD) has been previously demonstrated to induce melanoma cell apoptosis and reduce metastasis in mouse lungs. This study aimed at investigating the efficacy of the other hybrid compound with four-carbon spacer (IN4CPBD) and elucidating its anti-metastatic mechanism. Human melanoma A375 cells with IN4CPBD treatment underwent cytotoxicity and apoptosis-associated assays. Transwell migration assay, Western blotting, and ELISA were used for mechanistic study. IN4CPBD exhibited potent melanoma cytotoxicity through interrupting G1/S cell cycle progression, increasing DNA fragmentation and hypodipoidic DNA contents, and reducing mitochondrial membrane potential. Caspase activity elevation suggested that both intrinsic and extrinsic pathways were involved in IN4CPBD-induced melanoma apoptosis. IN4CPBD up-regulated p53 and p21, thereby concomitantly derailing the equilibrium between Bcl-2 and Bax levels. Transwell migration assay demonstrated that stromal cell-derived factor-1α (SDF-1α) stimulated A375 cell motility, while kinase inhibitors treatment confirmed that Rho/ROCK, Akt, ERK1/2, and p38 MAPK pathways were involved in SDF-1α-enhanced melanoma migration. IN4CPBD not only abolished the SDF-1α-enhanced chemotactic motility but also suppressed constitutive MMP-9 and VEGF expression. Mechanistically, IN4CPBD down-regulated Akt, ERK1/2, and p38 MAPK total proteins and MYPT1 phosphorylation. In conclusion, beyond the fact that IN4CPBD induces melanoma cell apoptosis at cytotoxic dose, the interruption in the VEGF expression and the SDF-1α-related signaling at cytostatic dose may partially constitute the rationale for its in vivo anti-metastatic potency.

Geldanamycin and its analog induce cytotoxicity in cultured human retinal pigment epithelial cells.

Geldanamycin (GA), a benzoquinone ansamycin, was originally isolated as a natural product with anti-fungal activity. GA and its analogs, including 17-allylamino-demethoxy geldanamycin (17-AAG), are also known to block the function of a molecular chaperone, heat shock protein 90 (Hsp90). In light of their anti-tumor properties through direct cytotoxicity and anti-angiogenicity, GA has been previously demonstrated to suppress hypoxia-induced VEGF production in retinal pigment epithelium (RPE) cells, implicating its applicability in treating intraocular neovascularization. This study aimed at investigating the effectiveness of Hsp90 inhibitor treatment in suppressing proliferation of cultured human RPE cells and elucidating its underlying mechanism. Cultured RPE cells were treated with GA or 17-AAG and subjected for cell proliferation assay and cell cycle analysis. Expression of apoptotic regulators and survival signaling activity were monitored by Western blotting. The results showed that both GA and 17-AAG significantly inhibited RPE cell proliferation at micromolar levels. Treatment with GA and 17-AAG led to growth arrests in G1 and S phases, increased sub-G1 hypodipoid cell population, induced apoptotic cell death, and upregulated P53 and P21 expression, although the drug-induced Bcl-2 upregulation cannot prevent cell death. Additionally, GA and 17-AAG significantly suppressed constitutive contents of phosphorylated ERK1/2 and total Akt proteins, and completely abrogated wortmannin-sensitized Akt phosphorylation. In conclusion, GA and 17-AAG inhibit RPE cell proliferation and induce cytotoxicity, possibly through downregulating Akt- and ERK1/2-mediated signaling activities. They might potentially constitute a therapeutic agent for ocular disorders with RPE over proliferation, such as proliferative vitreoretinopathy.

Anti-endothelial cell IgG from patients with chronic arsenic poisoning induces endothelial proliferation and VEGF-dependent angiogenesis.

An endemic peripheral vascular disorder due to chronic arsenic poisoning, named Blackfoot disease (BFD), occurs in Taiwan. BFD causes destruction of vascular endothelial cells, and an anti-endothelial cell IgG antibody was found in the sera of BFD patients. We studied the role of this IgG antibody (BFD-IgG) in modulating proliferation and angiogenesis of human umbilical vein endothelial cells (HUVECs) and found that a low concentration of BFD-IgG (200 microg/mL) stimulated endothelial cell growth and increased expressions of vascular cell adhesion molecule-1 (VCAM-1), nerve growth factor (NGF), and vascular endothelial growth factor (VEGF). The apoptosis events appeared not altered by addition of BFD-IgG. An in vitro neoangiogenesis assay demonstrated that BFD-IgG promoted the formation of tube-like structures, which was completely abrogated by anti-VEGF neutralizing antibody and partially by NOS inhibitor, L-NAME. We conclude that BFD-IgG at 200 microg/mL results in cell proliferation and enhanced VEGF-dependent angiogenesis in vitro. Those results suggested that a low concentration of BFD-IgG plays a protective role in the pathogenesis or the progression of BFD.

Design, synthesis, and biological evaluation of pyrrolo[2,1-c][1,4]benzodiazepine and indole conjugates as anticancer agents.

A series of novel pyrrolo[2,1-c][1,4]benzodiazepine (PBD) hybrids linked with indole carboxylates is described. These compounds were prepared by linking C-8 of 3 (DC-81) with an indole 2-carbonyl moiety (9) through carbon chain linkers to afford PBD hybrid agents 17-21 in good yields. Preliminary in vivo tests show that these hybrid agents have potent antitumor activity. The cytotoxic studies of the hybrid agents on human melanoma A2058 cells indicate most of the hybrids induced higher cytotoxicity, better DNA-binding ability, an increase in the apoptotic sub-G1 population, and a significant reduction in deltapsi(mt) relative to compound 3. In addition, DNA flow cytometric analysis shows that hybrids actively induce a marked loss of cells from the G2/M phase of the cell cycle, which progresses to early apoptosis as detected by flow cytometry after double-staining with annexin V and propidium iodide (PI). Thus, we suggest that the hybrid agents are potent inducers of cell apoptosis in A2058 cells.

Cytotoxicities, cell cycle and caspase evaluations of 1,6-diaryl-3(Z)-hexen-1,5-diynes, 2-(6-aryl-3(Z)-hexen-1,5-diynyl)anilines and their derivatives.

Compounds 3, 6-7, 9-10, 15-17, and 20-21 showed growth inhibition effects on a full panel of 60 human cancer cell lines, and most of the average IC50 values of the indicated analogues were from < 0.01 to 96.6 microM, in which analogues 16 and 17 revealed the highest cytotoxic activity with the cancer cell lines at 10(-7) M concentration range. During the cell cycle analysis, a moderate to high apoptotic progress induction was shown by 3, 9, 16-17, and 20 compared with the control, which 2-(6-(2-thienyl)-3(Z)-hexen-1,5-diynyl)aniline 16 showed the highest apoptotic effect. Structures 16-17 displayed a significant G2/M phase arrest in the cell growth cycle compared with other derivatives, which the proportions of the G2/M phase cells were accumulated to 71.5% and 82.6%, respectively. Moreover, the colorimetric assay of 16-17 also provided advanced evidence to the relationship between the compounds and the caspase-3 enzyme, which was one of the major promoters of apoptotic effect.

Effects of arsenic and UVB on normal human cultured keratinocytes: impact on apoptosis and implication on photocarcinogenesis.

Inorganic arsenic is an environmental toxin and a human carcinogen. Being a co-mutagen, arsenic enhances carcinogenesis of ultraviolet irradiation on the mouse skin. Apoptosis, a well-regulated cell death process, is essential for cell development and tissue homeostasis. Dysregulation of apoptosis will lead to various kinds of pathological conditions, such as cancers. The purpose of this study is to investigate the apoptotic effect induced by the interactions of arsenic and UVB on cultured human keratinocytes. Cultured keratinocytes were treated with sodium arsenite (1 microM) and/or UVB 50 mJ/cm2 irradiation in different combinations, including arsenic alone (As group), UVB alone (UVB group), arsenic followed by UVB (As/UVB group), and UVB followed by As (UVB/As group) treatments. Our results revealed that a low concentration of sodium arsenite did not induce keratinocytes apoptosis. The UVB group showed obvious elevation of caspase-8, -9, and -3 activities in addition to strong induction of apoptosis as determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling (TUNEL) assay. Similar pro-apoptotic effects were observed in the UVB/As group. In contrast, only subtle changes of cell morphology and survival rate were noticed in the As/UVB group. In addition, the results of Western blot and activity assay of caspase-8, -9, and -3 revealed that neither the receptor nor the mitochondrial apoptotic signaling pathway was activated in the As/UVB group. Therefore, we conclude that the pretreatment of keratinocytes with sodium arsenite decreased the pro-apoptotic effects induced by UVB. This finding corroborated with the animal model studying the effects of arsenic and UVB on carcinogenesis. The molecular mechanisms by which arsenic decreased UVB-induced apoptosis remain to be elucidated.

Remarkable G2/M phase arrest and apoptotic effect performed by 2-(6-aryl-3-hexen-1,5-diynyl) benzonitrile antitumor agents.

2-(6-aryl-3-hexen-1,5-diynyl)benzonitriles 3a-j showed growth inhibition effects on a full panel of 60 human cancer cell lines in low micro-concentrations, in which compounds 3c,d displayed a significant G2/M arrest in the cell growth cycle compared with other derivatives and an apoptotic progress induction were also shown by 3a-d.