Low-dose metronomic paclitaxel chemotherapy suppresses breast tumors and metastases in mice

This study investigated the use of low-dose metronomic (LDM) chemotherapy with paclitaxel in a highly metastatic mouse model of 4T1 breast cancers, and compared it with the maximum tolerable dose (MTD) therapy. LDM therapy displayed a stronger anti-tumor activity in suppressing primary and metastatic breast tumors with less degree of side effects, and stronger anti-angiogenic and anti-lymphangiogenic activities than MTD therapy. But MTD therapy showed stronger pro-apoptotic and anti-proliferative activities in situ. Paclitaxel therapy downregulated expression of vascular endothelial growth factor receptor-2 (VEGFR2) and up-regulated expression of thrombospondin-1. The results support the application of paclitaxel LDM therapy to treat advanced breast cancer.

Glycyrrhizin attenuates endotoxin- induced acute liver injury after partial hepatectomy in rats

Massive hepatectomy associated with infection induces liver dysfunction, or even multiple organ failure and death. Glycyrrhizin has been shown to exhibit anti-oxidant and anti-inflammatory activities. The aim of the present study was to investigate whether glycyrrhizin could attenuate endotoxin-induced acute liver injury after partial hepatectomy. Male Wistar rats (6 to 8 weeks old, weighing 200-250 g) were randomly assigned to three groups of 24 rats each: sham, saline and glycyrrhizin. Rats were injected intravenously with lipopolysaccharide (LPS) 24 h after 70% hepatectomy. Glycyrrhizin, pre-administered three times with 24 h intervals 48 h before hepatectomy, prolonged the survival of rats submitted to partial hepatectomy and LPS injection, compared with saline controls. Glycyrrhizin was shown to attenuate histological hepatic changes and significantly reduced serum levels of aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase, at all the indicated times (6 rats from each were sacrificed 1, 3, 6, and 9 h after LPS injection), compared with saline controls. Glycyrrhizin also significantly inhibited hepatocyte apoptosis by down-regulating the expression of caspase-3 and inhibiting the release of cytochrome C from mitochondria into the cytoplasm. The anti-inflammatory activity of glycyrrhizin may rely on the inhibition of release of tumor necrosis factor-a, myeloperoxidase activity, and translocation of nuclear factor-kappa B into the nuclei. Glycyrrhizin also up-regulated the expression of proliferating cell nuclear antigen, implying that it might be able to promote regeneration of livers harmed by LPS. In summary, glycyrrhizin may represent a potent drug protecting the liver against endotoxin-induced injury, especially after massive hepatectomy.

Oxymatrine attenuates intestinal ischemia/reperfusion injury in rats

PURPOSE

Intestinal ischemia/reperfusion (I/R) is a common and serious clinical condition. The anti-inflammatory and anti-apoptotic properties of oxymatrine, the extract from a traditional Chinese herb, Sophora flavescens Ait, have been shown to protect the liver from I/R injury and attenuate colitis. The objective of this study was to investigate if oxymatrine could attenuate intestinal I/R injury induced in rats.

METHODS

The experimental design consisted of three groups of 24 Wistar rats each: a sham-operation group (control group), a group subjected to intestinal I/R and then given saline (saline group), and a group subjected to intestinal I/R and then given oxymatrine (oxymatrine group). Intestinal I/R was induced by occluding the superior mesenteric artery for 45 min. Six rats from each group were killed at selected time points, and blood and intestinal samples were collected.

RESULTS

Morphological alteration, reduction of gamma-glutamyl transpeptidase (gamma-GGT) activity, and increased cell apoptosis confirmed intestinal I/R injury. The oxymatrine group had a significantly lower histological score and apoptosis index than the saline group, demonstrating that the preadministration of oxymatrine attenuated gut damage. Moreover, oxymatrine inhibited the production of lipid peroxides (LPO), decreased the serum levels of tumor necrosis factor (TNF)-alpha, and downregulated expression of phosphorylated p38 mitogen-activated protein kinase, Fas, and FasL, which had been elevated by I/R.

CONCLUSIONS

These results provide further evidence of the anti-inflammatory and anti-apoptotic activities of oxymatrine, which may become a potent drug for protecting the intestines against I/R injury.

Taurine attenuates multiple organ injury induced by intestinal ischemia reperfusion in rats

BACKGROUND

Intestinal ischemia reperfusion (II/R) is a serious clinical condition associated with simultaneous multiple organ dysfunction. The purpose of this study was to investigate whether taurine, an anti-oxidative, anti-inflammatory, and anti-apoptotic agent, could attenuate multiple organ injury induced by II/R.

MATERIALS AND METHODS

Taurine was intravenously injected to Wistar rats 30 min before II/R; physiological saline and sham operation served as controls. II/R was produced by occlusion of superior mesenteric artery for 60 min. Rats were randomly sacrificed 1.5, 3, 12, and 36 h after II/R; blood samples were collected for assessing alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), creatinine (Cr), and tumor necrosis factor-alpha (TNF-alpha), and intestines, livers, kidneys, and lungs were removed for histological examination of scoring injury severity and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling analysis. The amount of lipid peroxides (LPO) was measured in intestinal tissues, and expression of caspase-3 was detected in all of the tissues with Western blot analysis.

RESULTS

II/R resulted in injury to intestines as well as livers, kidneys, and lungs, evidenced by morphological alteration, increased cell apoptosis, and elevated serum levels of ALT, AST, BUN, and Cr. The damage reached peak 3 h after II/R. The intestinal LPO and serum levels of TNF-alpha were increased after II/R. Pre-administration of taurine significantly attenuated multiple organ injury as the histological score, apoptosis index, LPO, and levels of ALT, AST, BUN, Cr, and TNF-alpha were significantly lower compared with saline controls.

CONCLUSIONS

Taurine attenuates multiple organ injury induced by II/R. Although the mechanism needs further investigation, taurine inhibits production of intestinal LPO, release of TNF-alpha, cell apoptosis, and expression of caspase-3.

Arsenic trioxide induces different gene expression profiles of genes related to growth and apoptosis in glioma cells dependent on the p53 status

We have previously reported that As(2)O(3) affected cell cycle progression and cyclins D1 and B1 expression in two glioma cell lines differing in p53 status (U87MG-wt; T98G-mutated). In the present study, we further demonstrated that As(2)O(3) affected proliferation, viability and apoptosis of the two cell lines in a dose- and time-dependent manner, and T98G cells were more sensitive than U87MG cells to As(2)O(3) -induced apoptosis and inhibition of proliferation and viability. We further investigated the expression profiles of genes related with apoptosis and cell cycle in the two cell lines with a human cDNA-microarray (SuperArray) spotted with 267 genes of apoptosis and cell cycle. Thirty five genes were upregulated and 15 genes downregulated at least 2-fold by As(2)O(3) in U87-MG cells; whereas, 38 genes were upregulated and 21 genes downregulated at least 2-fold in T98G cells by As(2)O(3). After As(2)O(3) treatment, p53 expression was upregulated 56.5-fold in T98G cells, but only 6.0-fold in U87MG cells. The results indicate that As(2)O(3) suppresses the growth of U87MG cells mainly by regulating expression of genes of cell cycle arrest, stress and toxicity; whereas As(2)O(3) affects T98G cells mainly by regulating expression of genes belonging to Bcl-2, tumor necrotic factor receptor and ligand families. The data may be helpful for optimizing As(2)O(3) as an anti-cancer drug in the treatment of gliomas.

Specific COX-2 inhibitor, meloxicam, suppresses proliferation and induces apoptosis in human HepG2 hepatocellular carcinoma cells

BACKGROUND AND AIMS

Cyclooxygenase-2 (COX-2) is associated with carcinogenesis. The aim of this study was to investigate the expression of COX-2 in four hepatocellular carcinoma (HCC) cell lines, and evaluate the effect of a selective COX-2 inhibitor, meloxicam, in HepG2, a high COX-2 expressing cell line.

METHODS

Expression of COX-2 was detected using RT-PCR, Western blotting and immunohistochemical analysis. Cell proliferation was measured using MTT assay. Cell cycle distribution was determined by flow cytometry. Apoptosis was detected with TUNEL method. Expression of proliferating cell nuclear antigen (PCNA), cell cycle regulatory proteins including cyclins A, B1, D1 and E, and apoptosis-related proteins including Fas, Fas ligand and Bcl-2 were examined using Western blotting.

RESULTS

Cyclooxygenase-2 was intensely expressed in HepG2, HLE and BEL7402 cells, but weakly expressed in SMMC-7402 cells. Meloxicam suppressed proliferation of HepG2 cells in a dose- and time-dependent manner, resulting in cell cycle arrest in S phase and cell accumulation in G0/G1 phase. Expression of PCNA, cyclin A but not cyclin B1, cyclin D1 or cyclin E was down-regulated by meloxicam. Meloxicam also induced apoptosis of HepG2 cells, with increased expression of Fas ligand, but the expression of Fas and Bcl-2 was not affected by meloxicam treatment.

CONCLUSIONS

The present study demonstrates that the specific COX-2 inhibitor meloxicam suppresses proliferation and induces apoptosis in HCC cells that express COX-2, suggesting that COX-2 inhibition may offer a novel chemopreventive and therapeutic approach for HCC.

"Iron-saturated" bovine lactoferrin improves the chemotherapeutic effects of tamoxifen in the treatment of basal-like breast cancer in mice

BACKGROUND

Tamoxifen is used in hormone therapy for estrogen-receptor (ER)-positive breast cancer, but also has chemopreventative effects against ER-negative breast cancers. This study sought to investigate whether oral iron-saturated bovine lactoferrin (Fe-Lf), a natural product which enhances chemotherapy, could improve the chemotherapeutic effects of tamoxifen in the treatment of ER-negative breast cancers.

METHODS

In a model of breast cancer prevention, female Balb/c mice treated with tamoxifen (5 mg/Kg) were fed an Fe-Lf supplemented diet (5 g/Kg diet) or the base diet. At week 2, 4T1 mammary carcinoma cells were injected into an inguinal mammary fat pad. In a model of breast cancer treatment, tamoxifen treatment was not started until two weeks following tumor cell injection. Tumor growth, metastasis, body weight, and levels of interleukin 18 (IL-18) and interferon γ (IFN-γ) were analyzed.

RESULTS

Tamoxifen weakly (IC(50) ~ 8 μM) inhibited the proliferation of 4T1 cells at pharmacological concentrations in vitro. In the tumor prevention study, a Fe-Lf diet in combination with tamoxifen caused a 4 day delay in tumor formation, and significantly inhibited tumor growth and metastasis to the liver and lung by 48, 58, and 66% (all P < 0.001), respectively, compared to untreated controls. The combination therapy was significantly (all P < 0.05) more effective than the respective monotherapies. Oral Fe-Lf attenuated the loss of body weight caused by tamoxifen and cancer cachexia. It prevented tamoxifen-induced reductions in serum levels of IL-18 and IFN-γ, and intestinal cells expressing IL-18 and IFN-γ. It increased the levels of Lf in leukocytes residing in gut-associated lymphoid tissues. B, T and Natural killer (NK) cells containing high levels of Lf were identified in 4T1 tumors, suggesting they had migrated from the intestine. Similar effects of Fe-Lf and tamoxifen on tumor cell viability were seen in the treatment of established tumors.

CONCLUSIONS

The results indicate that Fe-Lf is a potent natural adjuvant capable of augmenting the chemotherapeutic activity of tamoxifen. It could have application in delaying relapse in tamoxifen-treated breast cancer patients who are at risk of developing ER-negative tumors.

Modulating the interaction of CXCR4 and CXCL12 by low-molecular-weight heparin inhibits hepatic metastasis of colon cancer

Liver metastasis is the major obstacle for prolonging the survival of colon cancer patients. Low-molecular-weight heparin (LMWH), a common drug for venous thromboembolism, has displayed beneficial effects in improving the survival of cancer patients, though the mechanism remains unclear. This study aimed to investigate the effects of LMWH on hepatic metastasis of colon cancer and its underlying molecular mechanism by targeting the interaction of the chemokine receptor CXCR4 and its ligand CXCL12 (formerly known as stromal cell-derived factor 1α, SDF-1α), as the CXCR4-CXCL12 axis has been shown to regulate the interaction of cancer cells and stroma. Experimental results revealed that LMWH (Enoxaparin, 3500-5500 Da) inhibited the CXCL12-stimulated proliferation, adhesion and colony formation of human colon cancer HCT-116 cells that highly expressed CXCR4. Interestingly, LMWH or an anti-CXCR4 blocking antibody diminished the migrating and invading abilities of HCT116 cells stimulated by the recombinant CXCL12 protein or liver homogenates which contained endogenous CXCL12 protein. Although LMWH did not significantly inhibit the growth of subcutaneous colon tumors, it significantly suppressed the formation of hepatic metastasis established by intrasplenic injection of colon cancer cells in nude Balb/c mice and also downregulated the expression of CXCL12 in hepatic sinusoidal endothelial cells. The results suggest that LMWH inhibits the formation of hepatic metastasis of colon cancer by disrupting the interaction of CXCR4 and CXCL12, supporting that perioperative administration of LMWH may help to prevent the seeding and subsequent growth of hepatic metastases of colon cancer cells.

LncRNA TTN-AS1 promotes the progression of cholangiocarcinoma via the miR-320a/neuropilin-1 axis

Neuropilin-1 regulated by miR-320a participates in the progression of cholangiocarcinoma by serving as a co-receptor that activates multiple signaling pathways. The present study sought to investigate upstream lncRNAs that control the expression of miR-320a/neuropilin-1 axis and dissect some of the underlying mechanisms. Here we report lncRNA TTN-AS1 (titin-antisense RNA1) acts as a sponging ceRNA to downregulate miR-320a and is highly expressed in human cholangiocarcinoma tissues and cells. The expression of the above three molecules is correlated with the clinicopathologic parameters of cholangiocarcinoma patients. In this study, multiple bioinformatics tools and databases were employed to seek potential lncRNAs that have binding sites with miR-320a and TTN-AS1 was identified because it exhibited the largest folds of alteration between cholangiocarcinoma and normal bile duct epithelial cells. The regulatory role of TTN-AS1 on miR-320a was further evaluated by luciferase reporter and RNA pulldown assays, coupled with in situ hybridization and RNA immunoprecipitation analyses, which showed that TTN-AS1 bound to miR-320a through an argonaute2-dependent RNA interference pathway in the cytoplasm of cholangiocarcinoma cells. Knockdown and overexpression assays showed that the regulatory effect between TTN-AS1 and miR-320 was in a one-way manner. TTN-AS1 promoted the proliferation and migration of cholangiocarcinoma cells via the miR-320a/ neuropilin-1 axis. The function of TTN-AS1 on tumor growth and its interaction with miR-320a were confirmed in animal models. Further mechanistic studies revealed that TTA-AS1, through downregulating miR-320a, promoted cell cycle progression, epithelial-mesenchymal transition, and tumor angiogenesis by upregulating neuropilin-1, which co-interacted with the hepatocyte growth factor/c-Met and transforming growth factor (TGF)-β/TGF-β receptor I pathways. In conclusion, the present results demonstrate that lncRNA TTA-AS1 is a sponging ceRNA for miR-320a, which in turn downregulates neuropilin-1 in cholangiocarcinoma cells, indicating these three molecules represent potential biomarkers and therapeutic targets in the management of cholangiocarcinoma.

Arsenic trioxide potentiates the anti-cancer activities of sorafenib against hepatocellular carcinoma by inhibiting Akt activation

Sorafenib is the standard first-line systemic drug for advanced hepatocellular carcinoma (HCC), but it also induces the activation of Akt, which contributes to the mechanisms for the resistance to sorafenib. Arsenic trioxide (ATO) is a currently clinically used anticancer drug and displays its anticancer activities by inhibiting Akt activation. Therefore, we hypothesized that ATO may potentiate the anti-cancer activities of sorafenib against HCC. The results have demonstrated that ATO synergized with sorafenib to inhibit the proliferation and promote the apoptosis of HCC cells by diminishing the increased activation of Akt by sorafenib. ATO was shown to inhibit the expression or activation of Akt downstream factors, including glycogen synthase kinase (GSK)-3β, mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (S6K), and eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1), which regulate cell apoptosis and were upregulated or activated by sorafenib. Both sorafenib and ATO downregulated the expression of cyclin D1, resulting in HCC cells arrested at G0/G1 phase. ATO downregulated the expression of Bcl-2 and Bcl-xL and upregulated the expression of Bax, indicating that ATO could induce the apoptosis of HCC cells through the intrinsic pathways; but sorafenib showed little effects on these proteins of Bcl-2 family. ATO synergized with sorafenib to suppress the growth of HCC tumors established in mice by inhibiting the proliferation and inducing the apoptosis of HCC cells in situ. These results indicate that ATO may be a potential agent that given in combination with sorafenib acts synergistically for treating HCC.

Bilirubin protects grafts against nonspecific inflammation-induced injury in syngeneic intraportal islet transplantation

Nonspecific inflammatory response is the major cause for failure of islet grafts at the early phase of intraportal islet transplantation (IPIT). Bilirubin, a natural product of heme catabolism, has displayed anti-oxidative and anti-inflammatory activities. The present study has demonstrated that bilirubin protected islet grafts by inhibiting nonspecific inflammatory response in a syngeneic rat model of IPIT. The inflammation-induced cell injury was mimicked by exposing cultured rat insulinoma INS-1 cells to cytokines (IL-1β, TNF-α and IFN-γ) in in vitro assays. At appropriate lower concentrations, bilirubin significantly attenuated the reduced cell viability and enhanced cell apoptosis induced by cytokines, and protected the insulin secretory function of INS-1 cells. Diabetic inbred male Lewis rats induced by streptozotocin underwent IPIT at different islet equivalents (IEQs) (optimal dose of 1000, and suboptimal doses of 750 or 500), and bilirubin was administered to the recipients every 12 h, starting from one day before transplantation until 5 days after transplantation. Administration of bilirubin improved glucose control and enhanced glucose tolerance in diabetic recipients, and reduced the serum levels of inflammatory mediators including IL-1β, TNF-α, soluble intercellular adhesion molecule 1, monocyte chemoattractant protein-1 and NO, and inhibited the infiltration of Kupffer cells into the islet grafts, and restored insulin-producing ability of transplanted islets.

The miR-141/neuropilin-1 axis is associated with the clinicopathology and contributes to the growth and metastasis of pancreatic cancer

BACKGROUND

Neuropilin-1 (NRP-1) is a non-tyrosine kinase receptor interacting with multiple signaling pathways that underpin the biological behavior and fate of cancer cells. However, in pancreatic cancer, the mechanisms underlying the function of NRP-1 in cell proliferation and metastasis and the involvement of regulatory upstream miRNAs remain unclear.

METHODS

Potential miRNAs were mined by using multiple bioinformatics prediction tools and validated by luciferase assays. The expression of NRP-1 and miRNA-141 (miR-141) in pancreatic tissues and cells was examined by immunohistochemistry, immunoblotting and/or real-time RT-PCR. Stable transfected cells depleted of NRP-1 were generated, and regulatory effects of miR-141 were investigated by transfecting cells with miR-141 mimics and anti-miR-141. Assays of cell viability, proliferation, cell cycle distribution, transwell migration and cell scratch were employed. Xenograft tumor models were established to assess the effects of NRP-1 depletion on tumorigenesis and liver metastasis, and therapeutic effects of miR-141 on tumor growth. The role of miR-141/NRP-1 axis in regulating epithelial-mesenchymal transition (EMT) by co-interacting the TGF-β pathway was examined.

RESULTS

In this study, of 12 candidate miRNAs identified, miR-141 showed the strongest ability to regulate NRP-1. In pancreatic cancer tissues and cells, the expression level of NRP-1 was negatively correlated with that of miR-141. NRP-1 was highly expressed in pancreatic cancer tissues compared with normal pancreatic tissues, and its expression levels were positively correlated with tumor grade, lymph metastasis and AJCC staging. NRP-1 depletion inhibited cell proliferation by inducing cell cycle arrest at the G0/G1 phase through upregulating p27 and downregulating cyclin E and cyclin-dependent kinase 2, and reduced cell migration by inhibiting EMT through upregulating E-cadherin and downregulating Snail and N-cadherin. Through downregulating NRP-1, miR-141 mimics showed a similar effect as NRP-1 depletion on cell proliferation and migration. NRP-1 depletion suppressed tumor growth and liver metastasis and miR-141 mimics inhibited the growth of established tumors in mice. NRP-1 depletion and/or miR-141 mimics inhibited the activation of the TGF-β pathway stimulated by TGF-β ligand.

CONCLUSIONS

The present results indicate that NRP-1 is negatively regulated by miR-141 and the miR-141/NRP-1 axis may serve as potentially valuable biomarkers and therapeutic targets for pancreatic cancer.

Recombinant adeno-associated virus-mediated TRAIL gene therapy suppresses liver metastatic tumors

To evaluate the tumoricidal activity of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) on disseminated liver metastatic tumors, we constructed a recombinant adeno-associated virus (rAAV) expressing the extracellular domain (95-281aa) of human TRAIL (TRAIL(95-281), and the recombinant virus was designated as rAAV-TRAIL) using the 3-plasmid, helper-virus-free, packaging system. Transduction of mouse lymphoma EL-4 cells and Jurkat T cells lead to the expression of TRAIL(95-281) protein in both virus-transduced cells and the culture media, along with apoptosis of these cells in vitro. The therapeutic potential of rAAV-TRAIL was then evaluated in an orthotopic transplanted mouse model mimicking liver cancer metastasis, which was established by injection of EL-4 cells into the liver of C57BL/6 mice via the hepatic portal veins. Subsequent intraportal vein injection of rAAV-TRAIL, not the control virus, into the liver of these mice resulted in significant suppression of tumor growth and prolonged survival, while normal hepatocyte toxicity is undetectable. Histological and biochemical analysis in tumor tissue and serum confirmed that TRAIL(95-281) was stably expressed in relatively high level in hepatocytes and was secreted into the serum in active trimeric form. Futhermore, the mechanism for rAAV-TRAIL to inhibit tumor growth was by inducing apoptosis of the tumor cells metastasizing to the livers. These results strongly suggest that the rAAV-TRAIL-mediated gene delivery could be a promising approach for the treatment of liver metastasis cancer.

Meloxicam executes its antitumor effects against hepatocellular carcinoma in COX-2- dependent and -independent pathways

BACKGROUND

Cyclooxygenase (COX)-2 is overexpressed in many types of cancers including hepatocellular carcinoma (HCC). Meloxicam, a selective COX-2 inhibitor, has shown potential therapeutic effects against HCC, but the mechanisms accounting for its anti-cancer activities remain unclear.

METHODS AND FINDINGS

Meloxicam inhibited the ability of human HCC cells expressing higher levels of COX-2 to migrate, invade, adhere and form colonies through upregulating the expression of E-cadherin and downregulating the expression of matrix metalloproteinase (MMP) -2. Meloxicam induced cell apoptosis by upregulating pro-apoptotic proteins including Bax and Fas-L, and downregulating anti-apoptotic proteins including survivin and myeloid cell leukemia-1 (Mcl-1), through inhibiting phosphorylation of AKT. Addition of prostaglandin E2 (PGE2), the major product of COX-2, could abrogate the effects of meloxicam on the expression of survivin and myeloid cell leukemia-1 (Mcl-1), but not Bax and Fas-L, indicating that meloxicam induces cell apoptosis via both COX-2-dependent and -independent pathways. Meloxicam also induced cell autophagy by upregulating Beclin 1 and light chain 3-II. Specific inhibition of autophagy by 3-methyladenine and chloroquine had little effect on cell apoptosis but could enhance the pro-apoptotic effects of meloxicam by further upregulating the expression of Bax.

CONCLUSIONS

Meloxicam executes its antitumor effects by targeting the COX-2/MMP-2/E-cadherin, AKT, apoptotic and autophagic pathways in COX-2-dependent and -independent pathways, and inhibition of cell autophagy could help to overcome the resistance to meloxicam-induced apoptosis in HCC.

The IL-6/STAT3 pathway regulates adhesion molecules and cytoskeleton of endothelial cells in thromboangiitis obliterans

Thromboangiitis obliterans (TAO) (also known as Buerger's disease) is an inflammatory vascular disease that predominantly affects small- and medium-sized blood vessels of extremities. Endothelial cells play critical roles in the initiation and progression of this disease, but the underlying mechanisms remain unclear. In the present study, we demonstrate that patients with TAO had significantly higher levels of interleukin-6 (IL-6), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) in their plasmas, and the involved arterial tissues expressed higher levels of phosphorylated signal transducer and activator of transcription 3 (p-STAT3), ICAM-1 and VCAM-1. In exploring the molecular mechanisms with human aortic endothelial cells (HAECs), we found that recombinant IL-6 activated the STAT3 pathway, leading to the upregulation and overproduction of ICAM-1 and VCAM-1. RhoA (Ras homolog family member A), eNOS (endothelial nitric oxide synthase) and MMP-9 (matrix metalloproteinase-9) participated in this cellular signaling, and their interaction regulated the expression of ICAM-1 and VCAM-1. The activated STAT3 pathway by IL-6 also modulated the cytoskeleton of HAECs by regulating phosphorylation of focal adhesion kinase (FAK) and acetylation of α-tubulin through interplaying with RhoA. In summary, the present results indicate that activation of the IL-6/STAT3 pathway contributes to the pathogenesis of TAO by regulating cellular adhesion molecules and cytoskeleton of vascular endothelial cells, suggesting that targeting this pathway may provide a potential approach for the management of TAO.

Hydrogen sulfide ameliorates acute lung injury induced by infrarenal aortic cross-clamping by inhibiting inflammation and angiopoietin 2 release

OBJECTIVE

Infrarenal aortic cross-clamping (IAC) is a common procedure during infrarenal vascular operations. It often causes ischemia-reperfusion injury to lower limbs, resulting in systemic inflammation response and damage to remote organs (particularly lungs). Hydrogen sulfide (H2S) is a gaseous mediator that has been shown to have a protective effect against lung injury.

METHODS

Wistar rats underwent IAC for 2 hours, followed by 4 hours of reperfusion. GYY4137 (a slow-releasing H2S donor) and dl-propargylglycine (PAG, an inhibitor of cystathionine γ-lyase) were preadministered to rats 1 hour before IAC, and their effects on severity of lung injury and related mechanisms were investigated.

RESULTS

IAC induced a significant increase in plasma levels of H2S, H2S-synthesizing activity, and cystathionine γ-lyase expression in lung tissues compared with sham operation. Administration of GYY4137 significantly increased the levels of H2S but had little effect on H2S-synthesizing activity, whereas PAG reduced H2S levels and H2S-synthesizing activity. Preadministration of GYY4137 significantly attenuated acute lung injury induced by IAC, evidenced by reduced histologic scores and wet lung contents; improved blood gas parameters; reduced cell counts and protein amounts in bronchoalveolar lavage fluids; and reduced myeloperoxidase activity in lung tissues and plasma levels of tumor necrosis factor α, interleukin 6, and interleukin 1β. However, PAG further aggravated the severity of lung injury and displayed opposite effects to GYY4137. In exploration of the mechanisms, we found that IAC increased the release of angiopoietin 2 (Ang2) and its expression in lung tissues. GYY4137 attenuated the increase of Ang2 release and expression and increased the phosphorylation of Akt and the activation of its downstream factors, glycogen synthase kinase 3β and ribosomal protein S6 kinase; PAG showed opposite effects.

CONCLUSIONS

The study indicates that H2S may play a protective role in IAC-induced acute lung injury in rats by inhibiting inflammation and Ang2 release.

Cyclic glycine-proline regulates IGF-1 homeostasis by altering the binding of IGFBP-3 to IGF-1

The homeostasis of insulin-like growth factor-1 (IGF-1) is essential for metabolism, development and survival. Insufficient IGF-1 is associated with poor recovery from wounds whereas excessive IGF-1 contributes to growth of tumours. We have shown that cyclic glycine-proline (cGP), a metabolite of IGF-1, can normalise IGF-1 function by showing its efficacy in improving the recovery from ischemic brain injury in rats and inhibiting the growth of lymphomic tumours in mice. Further investigation in cell culture suggested that cGP promoted the activity of IGF-1 when it was insufficient, but inhibited the activity of IGF-1 when it was excessive. Mathematical modelling revealed that the efficacy of cGP was a modulated IGF-1 effect via changing the binding of IGF-1 to its binding proteins, which dynamically regulates the balance between bioavailable and non-bioavailable IGF-1. Our data reveal a novel mechanism of auto-regulation of IGF-1, which has physiological and pathophysiological consequences and potential pharmacological utility.

Repositioning drugs for inflammatory disease - fishing for new anti-inflammatory agents

Inflammation is an important and appropriate host response to infection or injury. However, dysregulation of this response, with resulting persistent or inappropriate inflammation, underlies a broad range of pathological processes, from inflammatory dermatoses to type 2 diabetes and cancer. As such, identifying new drugs to suppress inflammation is an area of intense interest. Despite notable successes, there still exists an unmet need for new effective therapeutic approaches to treat inflammation. Traditional drug discovery, including structure-based drug design, have largely fallen short of satisfying this unmet need. With faster development times and reduced safety and pharmacokinetic uncertainty, drug repositioning - the process of finding new uses for existing drugs - is emerging as an alternative strategy to traditional drug design that promises an improved risk-reward trade-off. Using a zebrafish in vivo neutrophil migration assay, we undertook a drug repositioning screen to identify unknown anti-inflammatory activities for known drugs. By interrogating a library of 1280 approved drugs for their ability to suppress the recruitment of neutrophils to tail fin injury, we identified a number of drugs with significant anti-inflammatory activity that have not previously been characterized as general anti-inflammatories. Importantly, we reveal that the ten most potent repositioned drugs from our zebrafish screen displayed conserved anti-inflammatory activity in a mouse model of skin inflammation (atopic dermatitis). This study provides compelling evidence that exploiting the zebrafish as an in vivo drug repositioning platform holds promise as a strategy to reveal new anti-inflammatory activities for existing drugs.

Hydrogen sulfide protects cardiomyocytes from myocardial ischemia-reperfusion injury by enhancing phosphorylation of apoptosis repressor with caspase recruitment domain

Hydrogen sulfide (H(2)S) displays an anti-apoptotic activity against myocardial ischemia reperfusion (MIR). Apoptosis repressor with caspase recruitment domain (ARC) is constitutively expressed in the heart and inhibits cell apoptosis when it is phosphorylated. Here, we investigated whether H(2)S could inhibit apoptosis by affecting ARC phosphorylation using cultured rat cardiomyocytes and a rat model of MIR. Primary cardiomyocytes were prepared from hearts of newborn rats and were pre-incubated with NaHS, a donor of H(2)S, for 60 min. Cardiomyocytes were subjected to hypoxia for 4 h, followed by reoxygenation for 2 h. The hypoxia and subsequent reoxygenation (H/R) significantly induced cell apoptosis, increased expression levels of Fas and FasL proteins, enhanced release of cytochrome c from mitochondria, and elevated caspase-3 activity, while H/R reduced ARC phosphorylation and increased the activity of calcineurin that dephosphorylates ARC. Pre-incubation with NaHS significantly attenuated the above effects through promoting ARC phosphorylation by reducing calcineurin activity and by increasing the activity of protein kinase casein kinase II (CK2) that phosphorylates ARC. In fact, TBB, a specific inhibitor of CK2, abolished the effects of NaHS. In rats undergoing MIR, NaHS significantly reduced the myocardial infarct size, cell apoptosis, calcineurin activity, and the expression levels of Fas, FasL and cleaved caspase-3 proteins, while NaHS increased ARC phosphorylation. In contrast, DL-propargylglycine, an inhibitor of cystathionine γ-lyase, the main enzyme for H(2)S production in hearts, showed opposite effects to NaHS. The results indicate that H(2)S inhibits apoptosis of cardiomyocytes induced by MIR through enhancing ARC phosphorylation.

Overexpression of von Hippel-Lindau tumor suppressor protein and antisense HIF-1alpha eradicates gliomas

The von Hippel-Lindau tumor suppressor protein (pVHL) suppresses tumor formation by binding the alpha subunits of hypoxia-inducible-factors responsible for stimulating tumor angiogenesis and glycolysis, and targeting them for ubiquitination and proteasomal destruction. Loss of pVHL leads to tumorigenesis and development of sporadic renal cell carcinomas and central nervous system hemangioblastomas. In the present study, we investigated whether engineered overexpression of pVHL in C6 glioma cells, which already express endogenous pVHL, would suppress the tumorigenicity of this particular tumor cell type. C6 cells overexpressing VHL displayed a reduced growth rate (70% inhibition) compared to the parental cell line when subcutaneously implanted in athymic (nu/nu) mice. Growth inhibition was associated with a 50% reduction in the number of tumor vessels and a 60% increase in tumor cell apoptosis, due in part to downregulation of HIF-1, VEGF, and the antiapoptotic factor Bcl-2, respectively. Gene transfer of VHL suppressed the growth of established C6 gliomas, and synergized with antisense HIF-1 to completely eradicate tumors. The data suggest that VHL gene therapy and/or agents that increase VHL expression could have utility in the treatment of gliomas, particularly when combined with agents that inhibit the expression or function of HIF-1.

Antisense integrin alphaV and beta3 gene therapy suppresses subcutaneously implanted hepatocellular carcinomas

BACKGROUND

Integrin alphaVbeta3 plays a critical role in tumour angiogenesis and metastasis formation, and is recognized as a key therapeutic target in the treatment of cancer.

AIM

To investigate whether antisense alphaV and beta3 gene therapy has utility in the treatment of hepatocellular carcinomas.

METHODS

Antisense expression plasmids targeting integrin alphaV or beta3 were constructed, and examined by immunohistochemistry and Western blot analyses for their ability to inhibit alphaV and beta3 expression. The antisense alphaV and beta3 expression vectors, either alone or in combination, were injected into HepG2 hepatomas established subcutaneously in nude mice and tumour growth, angiogenesis and apoptosis were monitored.

RESULTS

Antisense alphaV and beta3 downregulated the alphaV and beta3 subunits expressed by human umbilical vein endothelial cells, and the alphaV subunit expressed by HepG2 cells. Gene transfer of antisense alphaV and beta3 expression vectors downregulated alphaV and beta3 in HepG2 tumours established in nude mice, inhibited tumour vascularization and growth, and enhanced tumour cell apoptosis. Antisense alphaV suppressed tumour growth more strongly than antisense beta3; however antisense therapy that simultaneously targeted both integrin subunits was more effective than the respective monotherapies. Antisense alphaV and beta3 inhibited tumour angiogenesis to similar extents, by a process that is independent of vascular endothelial growth factor.

CONCLUSIONS

Antisense gene therapy targeting alphaV integrins warrants consideration as an approach to treat hepatocellular carcinomas.

Enhanced induction of heme oxygenase-1 suppresses thrombus formation and affects the protein C system in sepsis

Heme oxygenase-1 (HO-1) displays anti-inflammatory and cytoprotective activities in sepsis. Here, we investigated the effects of HO-1 on thrombus formation and the protein C system in a septic C57BL/6 mouse model induced by cecal ligation and perforation (CLP). Septic mice were either preinjected with the vehicle, pretreated with hemin (an HO-1 inducer) or zinc protoporphyrin IX (ZnPP, an HO-1 inhibitor), or given a combination of hemin + ZnPP. CLP increased significantly the hepatic expression of HO-1; increased thrombosis in livers, kidneys, and lungs; shortened the prothrombin time (PT) and activated partial thromboplastin time (APTT); elevated the levels of tumor necrosis factor-1α (TNF-1α), interleukin-6 (IL-6), and thrombomodulin (TM); reduced the levels of protein C (PC) and activated protein C (aPC); and downregulated hepatic expression of PC and TM. The preadministration of hemin to septic mice increased the expression and activity of HO-1; inhibited thrombosis in the preceding 3 organs; prolonged PT and APTT; inhibited the production of TNF-α and IL-6; upregulated the expression of PC and TM in livers; elevated the plasma levels of PC and aPC; and reduced the plasma levels of TM. In contrast, ZnPP showed opposite effects to hemin and reversed the effects of hemin by inhibiting the activity of HO-1. The administration of tricarbonyl dichloro ruthenium (II) dimer (CORM-2), which is a CO-releasing molecule, had a similar effect to hemin on thrombosis and the protein C system. The data indicate that the enhanced induction of HO-1 inhibits thrombus formation and affects the protein C system in sepsis.

Antisense hypoxia-inducible factor 1alpha gene therapy enhances the therapeutic efficacy of doxorubicin to combat hepatocellular carcinoma

Hepatocellular carcinoma (HCC), one of the most common cancers worldwide, is resistant to anticancer drugs. Hypoxia is a major cause of tumor resistance to chemotherapy, and hypoxia-inducible factor (HIF)-1 is a key transcription factor in hypoxic responses. We have previously demonstrated that gene transfer of an antisense HIF-1alpha expression vector downregulates expression of HIF-1alpha and vascular endothelial growth factor (VEGF), and synergizes with immunotherapy to eradicate lymphomas. The aim of the present study was to determine whether gene transfer of antisense HIF-1alpha could enhance the therapeutic efficacy of doxorubicin to combat HCC. Both antisense HIF-1alpha therapy and doxorubicin suppressed the growth of subcutaneous human HepG2 tumors established in BALB/c nude mice, tumor angiogenesis, and cell proliferation, and induced tumor cell apoptosis. The combination therapy with antisense HIF-1alpha and doxorubicin was more effective in suppressing tumor growth, angiogenesis, and cell proliferation, and inducing cell apoptosis than the respective monotherapies. Gene transfer of antisense HIF-1alpha downregulated the expression of both HIF-1alpha and VEGF, whereas doxorubicin only downregulated VEGF expression. Antisense HIF-1alpha and doxorubicin synergized to downregulate VEGF expression. Both antisense HIF-1alpha and doxorubicin inhibited expression of proliferating cell nuclear antigen, and combined to exert even stronger inhibition of proliferating cell nuclear antigen expression. Antisense HIF-1alpha therapy warrants investigation as a therapeutic strategy to enhance the efficacy of doxorubicin for treating HCC.

Low-dose metronomic chemotherapy of paclitaxel synergizes with cetuximab to suppress human colon cancer xenografts

Low-dose metronomic (LDM) chemotherapy represents a new strategy to treat solid tumors by stronger antiangiogenic activity and lower side effects, especially in combination with other antiangiogenic agents. This study aims to investigate whether LDM chemotherapy of paclitaxel could synergize with cetuximab, an antiangiogenic agent to suppress HT-29 human colon tumors in BALB/c nude mice. To explore its possible mechanism, the tumor vascular status was detected by staining with anti-CD31 Ab and the tumoral expression of thrombospondin-1 was examined by immunohistochemistry, western blot analysis, and real-time PCR. Our results showed that empirical metronomic paclitaxel regimens in combination with cetuximab induces significant and durable antitumor responses without overt toxicity. Paclitaxel LDM chemotherapy displayed stronger antiangiogenic activity than maximum tolerable dose (MTD) chemotherapy, whereas MTD chemotherapy induced more apoptotic cells. The combinational therapy with LDM and cetuximab showed the strongest antiangiogenic activity among all the groups. Paclitaxel LDM chemotherapy also dramatically upregulated the expression of thrombospondin-1, but MTD chemotherapy did not. These results suggest that the combination of paclitaxel LDM chemotherapy and cetuximab represents a potent strategy to combat colon cancers.