Adeno-associated virus-mediated expression of kallistatin suppresses local and remote hepatocellular carcinomas

BACKGROUND

The current treatments for hepatocellular carcinoma (HCC) are poor, particularly for metastatic HCC. Intraportal transfusion of adeno-associated virus (AAV) leads to long-term and persistent transgenic expression in livers. Kallistatin, a novel angiogenesis inhibitor, exhibits anti-tumor activity. The aim of the study was to investigate whether intraportal injection of AAV-kallistatin could suppress local and metastatic HCC in mice.

METHODS

An AAV vector encoding kallistatin was constructed, and its transduction efficiency by intraportal transfusion in livers was examined by RT-PCR, immunohistochemical and Western blotting analysis. The anti-tumor activity was tested in three HCC models including hepatic and subcutaneous human Hep3B HCC tumors in BALB/c athymic (nu/nu) mice, and subcutaneous mouse BNL HCC tumors in BALB/c mice. Tumor cell proliferation in situ was examined by anti-Ki-67 staining, and apoptosis by TUNEL.

RESULTS

Gene transfection by rAAV-kallistatin inhibited proliferation of human umbilical vein endothelial cells and HCC cells in vitro. Intraportal injection of rAAV-kallistatin resulted in persistent and specific expression of kallistatin in livers detected by RT-PCR and immunohistochemical analysis, and kallistatin protein in circulation detected by Western blotting analysis. Intraportal injection of rAAV-kallistatin significantly suppressed angiogenesis and growth of hepatic Hep3B tumors. The kallistatin released by hepatocytes into the circulation suppressed remote Hep3B and BNL tumors established subcutaneously. The rAAV-kallistatin gene therapy significantly inhibited tumor cell proliferation and induced apoptosis.

CONCLUSIONS

Intraportal injection of rAAV-kallistatin suppressed hepatic and subcutaneous HCC tumors, relying on its anti-angiogenic and anti-proliferative activities.

Genistein synergizes with arsenic trioxide to suppress human hepatocellular carcinoma

Arsenic trioxide (ATO) is of limited therapeutic benefit for the treatment of solid tumors. Genistein exhibits anticancer and pro-oxidant activities, making it a potential candidate to enhance the efficacy of ATO whose cytotoxicity is oxidation-sensitive. This study sought to determine whether genistein synergizes with ATO to combat hepatocellular carcinoma (HCC). Three human HCC cell lines, namely HepG2, Hep3B, and SK-Hep-1, were incubated with ATO, genistein, or ATO + genistein. The cells were also pretreated with antioxidant agents N-acetyl-L-cysteine (NAC) or butylated hydroxyanisole (BHA). Cell viability, apoptosis, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (DeltaPsim), expression of Bcl-2, Bax, caspase-9, and -3, and release of cytochrome c into the cytosol were examined. The synergistic effect of ATO and genistein was also assessed using HepG2 xenografts subcutaneously established in BALB/c nude mice. The results show that genistein synergized with ATO to reduce viability, induce apoptosis, and diminish the DeltaPsim of cells. The combination therapy down-regulated Bcl-2 expression, up-regulated Bax expression, enhanced the activation of caspase-9 and -3, and increased the release of cytochrome c. The synergistic effect of ATO and genistein was diminished by pretreatment with NAC or BHA. Genistein increased the production of intracellular ROS, while ATO had little effect. Genistein synergized with a low dose of ATO (2.5 mg/kg) to significantly inhibit the growth of HepG2 tumors, and suppress cell proliferation and induce apoptosis in situ. There were no obvious side effects, as seen with a high dose of ATO (5 mg/kg). Combining genistein with ATO warrants investigation as a therapeutic strategy to combat HCC.

Antisense hypoxia-inducible factor-1alpha augments transcatheter arterial embolization in the treatment of hepatocellular carcinomas in rats

Transcatheter arterial embolization (TAE) is a standard treatment for unresectable hepatic malignancies. It blocks the arterial blood supply to the tumor, but blockade of the blood supply can be short-lived as collateral blood vessels develop, leading to the failure of TAE. Here we report that intraportal delivery of adeno-associated viral (AAV) vectors expressing antisense hypoxia-inducible factor-1alpha (HIF-1alpha) (AAV-ASHIF) augments TAE to combat hepatocellular carcinoma (HCC). Intraportal delivery of AAV-ASHIF led to long-term localized expression of transgenic ASHIF in rat liver, and suppressed the growth of CBRH7919 HCC tumors established in rat liver by inhibiting the formation of neovessels and tumor cell proliferation. TAE therapy caused the necrosis and shrinkage of liver tumors; however, neovessels quickly formed and the residual tumors underwent rapid expansion. TAE enhanced tumor and liver hypoxia, which in turn upregulated expression of HIF-1alpha, vascular endothelial growth factor, glucose transporter-1, lactate dehydrogenase A, and proliferating cell nuclear antigen. Intraportal injection of AAV-ASHIF augmented the therapeutic effects of TAE and diminished its undesirable effects, resulting in extensive tumor cell death and suppression of the growth of liver tumors. In conclusion, this study has revealed that HIF-1 impedes the response of liver tumors to TAE. Antisense HIF-1alpha therapy is warranted as an approach for enhancing the efficacy of TAE to treat unresectable liver cancers.

MicroRNA-21-Regulated Activation of the Akt Pathway Participates in the Protective Effects of H2S against Liver Ischemia-Reperfusion Injury

Maintaining a certain level of hydrogen sulfide (H2S) in ischemia-reperfusion (I/R) is essential for limiting injury to the liver. Exogenous H2S exerts protective effects against this injury, but the mechanisms remain unclear. Liver injury was induced in Wistar rats undergoing hepatic I/R for 30 min, followed by a 3-h reperfusion. Administration of GYY4137 (a slow-releasing H2S donor) significantly attenuated the severity of liver injury and was reflected by reduced inflammatory cytokine production and cell apoptosis, the levels of which were elevated by I/R, while DL-propargylglycine (PAG, an inhibitor of cystathionine γ-lyase [CSE]) aggravated liver injury. Delivery of GYY4137 significantly elevated the plasma levels of H2S and upregulated the expression of microRNA-21 (miR-21), leading to the activation of the Akt pathway, in rat livers subjected to I/R. To further investigate the protective mechanisms of H2S during liver I/R injury, we established a cell model of hypoxia/reoxygenation (H/R) by incubating Buffalo rat liver (BRL) cells under hypoxia for 4 h followed by normoxia for 10 h. The regulatory effect of miR-21 on the Akt pathway by downregulating phosphatase and tensin homolog (PTEN) was validated by luciferase assays. Incubation of sodium hydrosulfide (NaHS), an H2S donor, increased the expression of miR-21, attenuated the reduced cell viability and the increased apoptosis by H/R, in BRL cells. Anti-miR-21 abolished the protective effects of NaHS by inactivating the Akt pathway. In conclusion, the present results indicate the activation of the Akt pathway regulated by miR-21 participates in the protective effects of H2S against I/R-induced liver injury.

Role of ornithine decarboxylase in breast cancer

Ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis that decarboxylates ornithine to putrescine, has become a promising target for cancer research. The aim of this study is to investigate the role of ODC in breast cancer. We detected expression of ODC in breast cancer tissues and four breast cancer cell lines, and transfected breast cancer cells with an adenoviral vector carrying antisense ODC (rAd-ODC/Ex3as) and examined their growth and migration. ODC was overexpressed in breast cancer tissues and cell lines compared with non-tumor tissues and normal breast epithelial cells, and there was a positive correlation between the level of ODC mRNA and the staging of tumors. The expression of ODC correlated with cyclin D1, a cell cycle protein, in synchronized breast cancer MDA-MB-231 cells. Gene transfection of rAd-ODC/Ex3as markedly down-regulated expression of ODC and cyclin D1, resulting in suppression of proliferation and cell cycle arrest at G0-G1 phase, and the inhibition of colony formation, an anchorage-independent growth pattern, and the migratory ability of MDA-MB-231 cells. rAd-ODC/Ex3as also markedly reduced the concentration of putrescine, but not spermidine or spermine, in MDA-MB-231 cells. The results suggested that the ODC gene might act as a prognostic factor for breast cancer and it could be a promising therapeutic target.

Akirin2 is modulated by miR-490-3p and facilitates angiogenesis in cholangiocarcinoma through the IL-6/STAT3/VEGFA signaling pathway

Akirin2 is a key regulator of embryonic development and the innate immunity response. However, this regulator's role in tumorigenesis especially in cholangiocarcinoma (CCA) development has not been thoroughly elucidated to date. In the current work, we used RT-qPCR, western blot analysis, and immunohistochemistry (IHC) to explore the expression level of Akirin2, and the relationship between Akirin2 levels and clinicopathological characteristics was evaluated. The biological functions of Akirin2 were examined in vitro and in vivo by using a lentiviral vector system. Luciferase reporter assays were applied to detect the direct binding relationship between the 3'-UTR of Akirin2 mRNA and miR-490-3p. The results showed that Akirin2 was overexpressed in CCA and this upregulation was associated with a shorter overall survival. Silencing or overexpressing Akirin2 by lentiviral approaches significantly influenced CCA cell proliferation, migration, invasion, and angiogenesis. An in vivo tumor model further validated the oncogenic effect of Akirin2 on CCA cell growth, metastasis, and angiogenesis. Mechanistic studies demonstrated that Akirin2 induced angiogenesis by increasing the expression of VEGFA by activating the IL-6/STAT3 signaling pathway. Akirin2 promoted cell migratory and invasive potential by affecting the epithelial-mesenchymal transition (EMT) process. In addition, Akirin2 expression was negatively controlled by miR-490-3p in CCA cells, and miR-490-3p attenuated cell migration and angiogenesis in CCA cells by silencing Akirin2. Taken together, the data indicated that Akirin2 could be regulated by miR-490-3p at the posttranscriptional level and facilitate CCA cell progression via the IL-6/STAT3/VEGFA signaling pathway. The present study may expedite the development of novel therapeutic strategies for CCA.

Carvacrol alleviates ischemia reperfusion injury by regulating the PI3K-Akt pathway in rats

BACKGROUND

Liver ischemia reperfusion (I/R) injury is a common pathophysiological process in many clinical settings. Carvacrol, a food additive commonly used in essential oils, has displayed antimicrobials, antitumor and antidepressant-like activities. In the present study, we investigated the protective effects of carvacrol on I/R injury in the Wistar rat livers and an in vitro hypoxia/restoration (H/R) model.

METHODS

The hepatoportal vein, hepatic arterial and hepatic duct of Wistar rats were isolated and clamped for 30 min, followed by a 2 h reperfusion. Buffalo rat liver (BRL) cells were incubated under hypoxia for 4 h, followed normoxic conditions for 10 h to establish the H/R model in vitro. Liver injury was evaluated by measuring serum levels of alanine aminotransferase (ALT) and aspatate aminotransferase (AST), and hepatic levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondiadehyde (MDA), and hepatic histology and TUNEL staining. MTT assay, flow cytometric analysis and Hoechst 33258 staining were used to evaluate the proliferation and apoptosis of BRL cells in vitro. Protein expression was examined by Western Blot analysis.

RESULTS

Carvacrol protected against I/R-induced liver damage, evidenced by significantly reducing the serum levels of ALT and AST, histological alterations and apoptosis of liver cells in I/R rats. Carvacrol exhibited anti-oxidative activity in the I/R rats, reflected by significantly reducing the activity of SOD and the content of MDA, and restoring the activity of CAT and the content of GSH, in I/R rats. In the in vitro assays, carvacrol restored the viability and inhibited the apoptosis of BRL cells, which were subjected to a mimic I/R injury induced by hypoxia. In the investigation on molecular mechanisms, carvacrol downregulated the expression of Bax and upregulated the expression of Bcl-2, thus inhibited the activation of caspase-3. Carvacrol was also shown to enhance the phosphorylation of Akt.

CONCLUSION

The results suggest that carvacrol could alleviate I/R-induced liver injury by its anti-oxidative and anti-apoptotic activities, and warrant a further investigation for using carvacrol to protect I/R injury in clinic.

Angiostatin enhances B7.1-mediated cancer immunotherapy independently of effects on vascular endothelial growth factor expression

Tumors must develop an adequate vascular network to meet their increasing demands for nutrition and oxygen. Angiostatin, a multiple kringle (1-4)-containing fragment of plasminogen, is an effective natural inhibitor of tumor angiogenesis. Here we show that gene transfer of angiostatin into small (0.1 cm in diameter) solid EL-4 lymphomas established in syngeneic C57BL/6 mice led to reduced tumor angiogenesis and weak inhibition of tumor growth. In contrast, when angiostatin gene therapy was preceded by in situ gene transfer of the T-cell costimulator B7.1, large (0.4 cm in diameter) tumors were rapidly and completely eradicated, whereas B7.1 and angiostatin monotherapies were ineffective. Combined gene transfer of B7.1 and angiostatin generated potent systemic antitumor immunity that was effective in eradicating a systemic challenge of 10(7) EL-4 cells. Gene transfer of angiostatin expression plasmids led to overexpression of angiostatin in tumors, increased apoptosis of tumor cells, and decreased density of tumor blood vessels, which may allow the immune system to overcome tumor immune resistance. The latter effects were not the result of a decrease in vascular endothelial growth factor expression, as tumoral vascular endothelial growth factor expression increased slightly after angiostatin gene transfer, presumably in response to increasing hypoxia. These results suggest that combining immunogene therapy with a vascular attack by angiostatin is a particularly effective approach for eliciting antitumor immunity.

Matrine inhibits proliferation and induces apoptosis of human colon cancer LoVo cells by inactivating Akt pathway

The present study has investigated the anti-tumor activity and the underlying mechanisms of matrine on human colon cancer LoVo cells. Matrine inhibited the proliferation of the cells in dose- and time-dependent manners. The concentration required for 50 % inhibition (IC50) was 1.15, 0.738, and 0.414 mg/ml, when cell were incubated with matrine for 24, 48, and 72 h, respectively. Matrine induced cell cycle arrest at G1 phase by downregulating cyclin D1 and upregulating p27 and p21. Matrine induced cell apoptosis by reducing the ratio of Bcl-2/Bax and increasing the activation of caspase-9 in a dose-dependent manner. Matrine displayed its anti-tumor activity by inactivating Akt, the upstream factor of the above proteins. Matrine significantly reduced the protein levels of pAkt, and increased the protein levels of other downstream factors, pBad and pGSK-3β. Specific inhibition of pAkt induced cell apoptosis, and synergized with matrine to inhibit the proliferation of LoVo cells; whereas activation of Akt neutralized the inhibitory effect of matrine on cell proliferation. The present study has demonstrated that matrine inhibits proliferation and induces apoptosis of human colon cancer LoVo cells by inactivating Akt pathway, indicating matrine may be a potential anti-cancer agent for colon cancer.

Role of the spleen in cyclophosphamide-induced hematosuppression and extramedullary hematopoiesis in mice

BACKGROUND AND AIMS

Extramedullary hematopoiesis (EMH) is induced in spleens due to various diseases. The aim of this study is to investigate the role of spleen in cyclophosphamide (CTX)-induced hematosuppression and EMH in mice.

METHODS

Balb/c mice were IP injected with 300 mg/kg CTX 2 weeks after splenectomy or sham operation and randomly sacrificed 1, 3, 7, 14, and 21 days after injection. Blood samples were collected, and spleens were weighed, histologically analyzed, and then used for flow cytometry.

RESULTS

There were significant differences in white blood count, red blood count, platelet numbers and hemoglobin concentration between the splenectomized and sham-operated mice after CTX injection. The cellularity of the spleen was reduced 3 days following CTX treatment but then rose 7 days after CTX treatment. The numbers of colony-forming units in the spleen reached a peak 7 days after CTX injection, then declined. Flow cytometry demonstrated the percentage of CD34(+) and CD117(+) cells in the spleen increased 7 days after CTX injection, indicating the hematopoietic stem and progenitor cells in the spleen.

CONCLUSIONS

The study indicates that EMH occurs as a compensatory reaction to CTX-induced hematosuppression in the murine spleen, implying that conservation of the spleen may promote the recovery of cancer patients from chemotherapy-induced hematosuppression.

Meloxicam suppresses hepatocellular carcinoma cell proliferation and migration by targeting COX-2/PGE2-regulated activation of the β-catenin signaling pathway

Recurrence and metastasis are the two leading causes of poor prognosis of hepatocellular carcinoma (HCC) patients. Cyclooxygenase (COX)-2 is overexpressed in many types of cancers including HCC and promotes its metastasis. Meloxicam is a selective COX-2 inhibitor that has been reported to exert an anti-proliferation and invasion/migration response in various tumors. In this study, we examined the role of meloxicam on HCC cell proliferation and migration and explored the molecular mechanisms underlying this effect. We found that meloxicam inhibited HCC cell proliferation and had a cell cycle arrest effect in human HCC cells. Furthermore, meloxicam suppressed the ability of HCC cells expressing higher levels of COX-2 and prostaglandin E2 (PGE2) to migration via potentiating expression of E-cadherin and alleviating expression of matrix metalloproteinase (MMP)-2 and -9. COX-2/PGE2 has been considered to activate the β-catenin signaling pathway which promotes cancer cell migration. We found that treatment with PGE2 significantly enhanced nuclear accumulation of β-catenin and the activation of GSK3β which could be reversed by meloxicam in HCC cells. We also observed that HCC cell migration and upregulation of the level of MMP-2/9 and downregulation of E-cadherin induced by PGE2 were suppressed by FH535, an inhibitor of β-catenin. Taken together, these findings provide a new treatment strategy against HCC proliferation and migration.

Gene transfer of endostatin enhances the efficacy of doxorubicin to suppress human hepatocellular carcinomas in mice

Hepatocellular carcinoma (HCC) is one of the most common cancer-related causes of death, and is chemoresistant to anticancer drugs. Anti-angiogenic therapy has been shown to enhance the efficacy of chemotherapy to treat solid tumors. The aim of the present study was to determine whether endostatin, a potent antiangiogenic agent, could enhance the efficacy of doxorubicin to combat HCC. An endostatin expression plasmid was constructed and its expression in vitro and in vivo was detected after gene transfer. Recombinant endostatin inhibited angiogenesis in the chorioallantoic membrane assay, and showed synergistic effects with doxorubicin in inhibiting the in vitro proliferation of endothelial cells, but not that of tumor cells. Both endostatin gene therapy and doxorubicin suppressed the growth of subcutaneous human HepG2 tumors established in BALB/c nude mice, and tumor angiogenesis. Combination therapy with endostatin gene therapy and doxorubicin showed a stronger effect in suppressing tumor growth, and tumor angiogenesis, than the respective monotherapies. Gene transfer of endostatin down-regulated the expression of both hypoxia-inducible factor-1alpha and vascular endothelial growth factor (VEGF), whereas doxorubicin only down-regulated VEGF expression. Endostatin and doxorubicin synergized to down-regulate VEGF expression. Endostatin and doxorubicin combination therapy warrants investigation as a therapeutic strategy to combat HCC.

Intramuscular delivery of antiangiogenic genes suppresses secondary metastases after removal of primary tumors

The success of surgery to remove primary tumors can be compromised by the subsequent outgrowth of metastases. It is recognized that primary tumors secrete antiangiogenic factors that suppress the outgrowth of their daughter metastases. In accord we show here that surgical removal of primary EL-4 lymphomas led to a marked decrease in the levels of circulating angiostatin and endostatin, and promoted the growth of distant nodular tumors. Expression vectors encoding angiostatin and endostatin, formulated with poly-N-vinyl pyrrolidone (PVP), were injected into the tibialis and gastrocnemia muscles, leading to expression of angiostatin and endostatin in muscle fibers. High levels of biologically active exogenous proteins were secreted into the circulation. Intramuscular gene therapy with angiostatin and endostatin plasmids significantly inhibited tumor vascularity and induced tumor cell apoptosis, and thereby suppressed the growth of secondary subcutaneous and disseminated metastatic tumors in the lung and liver. Simultaneous intramuscular delivery of both angiostatin and endostatin plasmids significantly prolonged the survival of mice after removal of primary tumors. These results suggest that intramuscular gene transfer of angiostatin and endostatin might serve as a prophylactic cancer-prevention strategy to combat the recurrence of cancer after surgical resection of primary tumors.

Vascular endothelial growth factor gene delivery by magnetic DNA nanospheres ameliorates limb ischemia in rabbits

BACKGROUND

Critical limb ischemia often leads to disability and limb loss. Vascular endothelial growth factor (VEGF), delivered either as recombinant protein or as gene therapy, has been shown to promote arteriogenesis and angiogenesis in animal models of limb ischemia. However, most of the studies used a nonspecific targeting system.

MATERIALS AND METHODS

Magnetic DNA nanospheres containing expression plasmids encoding VEGF were synthesized, and their morphology, magnetropism, and stability were analyzed. The magnetic DNA nanospheres were administrated via an artery into a rabbit limb ischemia model. The expression of VEGF and vascularization were examined by immunohistochemistry. The angiography was taken to evaluate arteriogenesis.

RESULTS

Magnetic DNA nanospheres were very stable and showed a high magnetropism. Gene delivery of such nanospheres via artery under a magnetic field led to the overexpression of VEGF in situ. The capillary density and capillary to muscle fiber ratio were doubled compared with those of the control animals. The arteriogenesis also was promoted in VEGF gene therapy group compared with controls but at later interval than capillary angiogenesis.

CONCLUSIONS

Our results suggest that intra-arterial VEGF gene delivery by magnetic DNA nanosphere promotes angiogenesis and arteriogenesis and presents a potent therapeutic strategy for critical limb ischemia.

Regression of solid tumors by engineered overexpression of von Hippel-Lindau tumor suppressor protein and antisense hypoxia-inducible factor-1alpha

The von Hippel-Lindau tumor suppressor protein (pVHL) suppresses tumor formation by binding the alpha subunits of hypoxia-inducible factors (HIFs) responsible for stimulating tumor angiogenesis and glycolysis, targeting them for ubiquitination and proteasomal destruction. Loss of pVHL leads to the development of sporadic renal cell carcinomas (RCCs). In the present study, we sought to determine whether engineered overexpression of pVHL in tumors other than RCC can inhibit tumor growth, either as a monotherapy, or in combination with antisense HIF-1alpha therapy. Intratumoral injection of subcutaneous EL-4 thymic lymphomas with an expression plasmid encoding pVHL resulted in the downregulation of HIF-1alpha and vascular endothelial growth factor (VEGF). There was a concomitant reduction in tumor angiogenesis and increased tumor cell apoptosis due in part to downregulation of Bcl-2 expression. VHL therapy resulted in the complete regression of small (0.1 cm diameter) tumors whereas, in contrast, large (0.4 cm diameter) EL-4 tumors were only slowed in their growth. Nevertheless, large tumors completely regressed in response to intratumoral injection of a combination of antisense HIF-1alpha and VHL plasmids. Combination therapy resulted in increased losses of HIF-1alpha, VEGF, and tumor blood vessels, and increased tumor cell apoptosis. These novel results suggest that synergistic therapies that simultaneously block the expression or function of HIF-1alpha, and enhance the expression or function of VHL may be beneficial in the treatment of cancer.

Antisense HIF-1alpha prevents acquired tumor resistance to angiostatin gene therapy

Angiostatin is a naturally occurring inhibitor of angiogenesis that is being developed as a drug to fight cancer. In this study we reveal that EL-4 tumors established in mice rapidly develop resistance to angiostatin gene therapy by upregulating hypoxia-inducible pathways. Angiostatin initially delayed tumor growth for 6 days by reducing blood vessel density. However, tumors quickly responded by upregulating the production of hypoxia-inducible factor-1alpha (HIF-1alpha) and its effector vascular endothelial growth factor (VEGF) in response to increasing tumor hypoxia, leading to restored angiogenesis and rapid tumor growth. Theoretically, blockade of HIF-1 should prevent resistance to anti-angiogenic therapy by preventing a tumor from responding to induced hypoxia. Antisense HIF-1alpha inhibited the expression of HIF-1alpha and of the HIF-1 effectors VEGF, glucose transporter-1 and lactate dehydrogenase. As a monotherapy, it was effective in eradicating small 0.1 cm diameter tumors, but only delayed the growth of large 0.4 cm diameter tumors. In contrast, timed injection of a combination of angiostatin and antisense HIF-1alpha plasmids completely eradicated large EL-4 tumors within 2 weeks, and prevented upregulation of hypoxia-inducible pathways induced by angiostatin. The data indicate that blocking hypoxia-inducible pathways by antisense HIF-1alpha can circumvent hypoxia-induced drug resistance and thereby augment the efficacy of anti-angiogenic therapies.

Matrine attenuates endotoxin-induced acute liver injury after hepatic ischemia/reperfusion in rats

PURPOSE

Hepatic ischemia/reperfusion (HIR) injury is an unavoidable consequence of major liver surgery, during which endotoxemia often takes place. This study aimed to investigate whether matrine has a protective effect against HIR-induced liver injury aggravated by endotoxin.

METHODS

Wistar rats were subjected to 30 min of HIR followed by lipopolysaccharide (LPS) (0.5 mg/kg) administration. At the indicated time points, six rats from each group (24 rats) were randomly euthanized to collect blood samples and livers.

RESULTS

Preadministration of matrine protected livers from injury induced by HIR+LPS as the histological score, myeloperoxidase activity and malondialdehyde contents, expression of macrophage-inflammatory protein-2, DNA-binding activity of nuclear factor κB, and serum levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, tumor necrosis factor-α, soluble intercellular adhesion molecule-1, and nitric oxide were significantly reduced, and serum levels of interleukin-6 were further increased. HIR+LPS markedly induced cell apoptosis and necrosis, and upregulated the expression of cleaved caspase-3, Fas, and FasL. Matrine significantly reduced cell necrosis, but had a nonsignificant inhibitory effect on cell apoptosis and expression of cleaved caspase-3 and FasL.

CONCLUSIONS

Matrine attenuates endotoxin-induced acute liver injury after HIR mainly by its anti-inflammatory and antioxidative activities, and has little inhibitory effect on cell apoptosis.

Downregulation of developmentally regulated endothelial cell locus-1 inhibits the growth of colon cancer

Developmentally regulated endothelial cell locus-1 (Del1) is an embryonic angiogenic factor expressed in early embryonic endothelial cells, but recently has been found to be expressed in some forms of cancers including colon and breast cancers, and melanoma, and human cancer cell lines. Overexpression of Del1 accelerates tumor growth by enhancing vascular formation, implying Del1 may be a potential target for anti-angiogenic cancer therapy. The study aims to investigate whether downregulation of Del1 could inhibit the growth of tumors established in nude Balb/c mice by subcutaneous implantation of human LS-174T colon cancer cells. The shRNA expression vectors targeting human Del1, and vascular endothelial growth factor (VEGF) were constructed. Gene transfection of Del1-shRNA downregulated expression of Del1 in LS-174T cells in vivo and in vitro, but did not alter the proliferative or survival properties of cells in vitro. Gene transfection of VEGF-shRNA downregulated expression of both VEGF and Del1 in LS-174T cells in vivo and in vitro. Both Del1-shRNA and VEGF-shRNA gene therapies exhibited anti-tumor activities and they also showed a synergistic effect in suppressing growth of colon tumors by anti-angiogenesis and anti-proliferation. Although further investigation to clarify the mechanisms explaining the role of Del1 in tumor growth, and the interaction between VEGF and Del1, is required, the results indicate that downregulation of Del1 presents a potent therapeutic strategy to combat colon cancer.

Combining kallistatin gene therapy and meloxicam to treat hepatocellular carcinoma in mice

Hepatocellular carcinoma (HCC) is one of the most common cancer-related causes of death, and conventional treatments offer unsatisfactory response. We have previously reported that kallistatin gene therapy suppressed the growth of HCC tumors by its anti-angiogenic activity, and meloxicam, a selective COX-2 inhibitor, inhibited proliferation and induced apoptosis of human HCC cells in vitro. The aim of this study was to determine whether combining kallistatin gene therapy and meloxicam could offer a better therapeutic effect to combat HCC in mice. A kallistatin expression plasmid was constructed and its expression was detected after intratumoral gene transfer. Both kallistatin gene therapy and meloxicam suppressed the growth of subcutaneous human HepG2 tumors established in BALB/c nude mice, and the combinational therapy showed a stronger effect in suppressing tumor growth, tumor angiogenesis and cell proliferation, and increasing cell apoptosis, than the respective monotherapies. Gene transfer of kallistatin inhibited tumor angiogenesis, and slightly inhibited cell proliferation and increased cell apoptosis in situ, but had no effect on expression of vascular endothelial growth factor, basic fibroblast growth factor, proliferating cell nuclear antigen, Bcl-2, Bax, or activation of caspase-3. Meloxicam therapy inhibited cell proliferation, induced cell apoptosis, reduced expression of proliferating cell nuclear antigen, increased activation of caspase-3, and upregulated Bax. Meloxicam also slightly inhibited tumor angiogenesis with no effect on the expression of vascular endothelial growth factor or basic fibroblast growth factor. Combining two novel anticancer agents, kallistatin targeting tumoral vascularization and meloxicam targeting cell proliferation and apoptosis, warrants investigation as a therapeutic strategy to combat HCC.

Reductive metabolism of the dinitrobenzamide mustard anticancer prodrug PR-104 in mice

PURPOSE

PR-104, a bioreductive prodrug in clinical trial, is a phosphate ester which is rapidly metabolized to the corresponding alcohol PR-104A. This dinitrobenzamide mustard is activated by reduction to hydroxylamine (PR-104H) and amine (PR-104M) metabolites selectively in hypoxic cells, and also independently of hypoxia by aldo-keto reductase (AKR) 1C3 in some tumors. Here, we evaluate reductive metabolism of PR-104A in mice and its significance for host toxicity.

METHODS

The pharmacokinetics of PR-104, PR-104A and its reduced metabolites were investigated in plasma and tissues of mice (with and without SiHa or H460 tumor xenografts) and effects of potential oxidoreductase inhibitors were evaluated.

RESULTS

Pharmacokinetic studies identified extensive non-tumor reduction of PR-104A to the 5-amine PR-104H (identity of which was confirmed by chemical synthesis), especially in liver. However, high concentrations of PR-104H in tumors that suggested intra-tumor activation is also significant. The tissue distribution of PR-104M/H was broadly consistent with the target organ toxicities of PR-104 (bone marrow, intestines and liver). Surprisingly, hepatic nitroreduction was not enhanced when the liver was made more hypoxic by hepatic artery ligation or breathing of 10% oxygen. A screen of non-steroidal anti-inflammatory drugs identified naproxen as an effective AKR1C3 inhibitor in human tumor cell cultures and xenografts, suggesting its potential use to ameliorate PR-104 toxicity in patients. However, neither naproxen nor the pan-CYP inhibitor 1-aminobenzotriazole inhibited normal tissue reduction of PR-104A in mice.

CONCLUSIONS

PR-104 is extensively reduced in mouse tissues, apparently via oxygen-independent two-electron reduction, with a tissue distribution that broadly reflects toxicity.

Hepatic overexpression of heme oxygenase-1 improves liver allograft survival by expanding T regulatory cells

BACKGROUND

Heme oxygenase (HO)-1 protects transplanted organs from ischemia reperfusion injury and immune rejection. This study sought to investigate whether persistent overexpression of HO-1 in donor livers could improve the survival by expanding T regulatory cells in a rat model of orthotopic liver transplantation.

METHODS

Livers of Dark Agouti rats were intraportally perfused with an AAV expression vector encoding rat HO-1 (AAV-HO-1), and then transplanted into Lewis rats. The survival, HO-1 activity, Banff rejection activity index, serum levels of IL-2 and TNF-α, infiltration of CD4(+), CD8(+), and T(reg) (CD4(+)CD25(+)Foxp3(+)) cells into donor livers, and expression of Foxp3, TGF-β, and IL-10 were examined. A mixed lymphocyte reaction (MLR) was performed.

RESULTS

Intraportal delivery of AAV-HO-1 resulted in persistent expression of HO-1 and increased activity of HO-1 in transplanted livers, leading to prolonged survival of recipients. Overexpression of HO-1 reduced the Banff rejection activity index, and production of IL-2 and TNF-α, inhibited infiltration of CD4(+) and CD8(+) cells, and increased infiltration of T(reg) cells, into donor livers. The spleens of recipients expressed higher levels of Foxp3, TGF-β, and IL-10 than those of control rats, and the transplanted livers expressed higher levels of Foxp3 and TGF-β. Splenocytes from the tolerant recipients had higher percentages of T(reg) cells, and responded poorly to the allogeneic donor splenocytes.

CONCLUSIONS

Persistent expression of HO-1 in donor livers by intraportal delivery of AAV-HO-1 improves the survival by expanding T(reg) cells. HO-1-based therapies, as described herein, promise new strategies to prevent the rejection of liver transplants.

Intravenous administration of arsenic trioxide encapsulated in liposomes inhibits the growth of C6 gliomas in rat brains

Arsenic trioxide (ATO) is a potent anti-tumor agent used to treat acute promyelocytic leukemia (APL), and more recently solid tumors including gliomas. However, the dose of ATO required to suppress gliomas is markedly higher than that used to treat APL, which leads to toxicity and undesirable side-effects, even though the local concentration of ATO in brains is relatively low after systemic administration. In an attempt to minimize the toxicity, enhance the penetrating activity across the blood-brain barrier, and reduce enzyme degradation, we prepared ATO encapsulated in liposomes, and investigated its therapeutic effect on C6 gliomas established in rat brains. The prepared ATO liposomes were stable at room temperature for 3 days and the latency rate was over 90% within 72 h. Intravenous injection of ATO liposomes led to a much higher concentration of ATO (5- fold, compared with ATO solution) in rat brains, resulting in inhibition of C6 gliomas in brains and prolonging the survival of rats bearing brain gliomas. ATO-liposome therapy resulted in fewer side effects, compared with free ATO solution. ATO-liposome therapy inhibited tumor angiogenesis by downregulating the expression of vascular endothelial growth factor (VEGF), and inducing cell apoptosis. The results warrant future investigation of the use of ATO encapsulated in liposomes to treat gliomas.

Depletion of histone deacetylase 1 inhibits metastatic abilities of gastric cancer cells by regulating the miR-34a/CD44 pathway

Overexpression of histone deacetylases (HDACs) is associated with higher metastatic rates and a poor prognosis in gastric cancer. However, the underlying mechanisms involved remain unclear. The present study aimed to investigate the molecular pathways that are involved in HDAC1-mediated metastatic activities in gastric cancer cells. First we used a microRNA (miRNA or miR) microarray to screen potential miRNAs whose expression can be altered by HDAC1 depletion. Of these miRNAs, miR-34a is important as it is often inactivated in cancer cells and acts as a tumor suppressor for various types of cancer. The reverse transcription-quantitative polymerase chain reaction (RT‑qPCR) results confirmed that miR-34a was upregulated by HDAC1 knockdown. Cells depleted of HDAC1 had lower abilities to migrate, invade and adhere, which were restored by a miR-34a antagomiR. Depletion of HDAC1 also resulted in impaired microfilaments and microtubules, while co-transfection of the miR-34a antagomiR attenuated these changes in the cellular cytoskeleton. The HDAC1/miR-34a axis regulated the expression and activation of CD44 and its downstream factors including Bcl-2, Ras homolog family member A (RhoA), LIM domain kinase 1 (LIMK-1) and matrix metalloproteinase (MMP)-2. The latter three proteins were responsible for the organization of tubulin and actin cytoskeleton and the formation of cellular pseudopodia. In conclusion, results of the present study indicated that HDAC1 depletion inhibits the metastatic abilities of gastric cancer cells by regulating the miRNA-34a/CD44 pathway, which may be a potential target for the treatment of gastric cancer.

Oral administration of lactoferrin attenuates intestinal ischemia-reperfusion injury in rats

BACKGROUND

Intestinal ischemia-reperfusion (I/R) is a common and serious clinical condition. Lactoferrin (Lf) has displayed antioxidative and anti-inflammatory activities in protecting the intestinal mucosa. The objective of this study was to investigate whether oral administration of Lf could attenuate I/R-induced intestinal injury.

METHODS

The experimental design consisted of three groups of Wistar rats (24 per group): sham operation, control (I/R, saline), Lf (I/R, Lf). Intestinal I/R was produced by occlusion of the superior mesenteric artery for 45 min. Eight rats from each group were randomly sacrificed 3, 12 or 36 h after reperfusion, and blood and intestinal samples were collected.

RESULTS

Intestinal I/R resulted in gut damage evidenced by morphological alteration, reduction of γ-glutamyl transpeptidase (γ-GGT) activity and increased cell apoptosis. Daily administration of Lf (200 mg/kg) for 14 days before surgery significantly attenuated gut damage by reducing the histologic score and apoptosis index, and restoring intestinal γ-GGT activity. Lf reduced intestinal malondialdehyde and myeloperoxidase, restored glutathione and decreased serum levels of tumor necrosis factor-α, interleukin (IL)-1β and IL-6 compared with saline control in I/R rats. In addition, oral administration of Lf did not produce any significant effects in healthy rats; Lf at doses of 50 or 100 mg/kg also attenuated I/R-induced gut damage, but administration of Lf for 7 days did not exert a significant protective effect against I/R-induced gut damage.

CONCLUSIONS

These results indicate that Lf may serve as a potent supplement in protecting the gut from intestinal I/R-induced injury by its antioxidative, anti-inflammatory and antiapoptotic activities.

T7 peptide inhibits angiogenesis via downregulation of angiopoietin-2 and autophagy

Angiogenesis is required for the invasion, metastasis and chemoresistance of tumor cells. In addition to vascular endothelial cell growth factor (VEGF), angiopoietin-2 (Ang2) is considered to be a promising target for anti-angiogenic therapy. The T7 peptide, an active fragment of full-length tumstatin [the noncollagenous 1 domain of the type IV collagen α3 chain, α3(IV)NC1], has equivalent anti-angiogenic activity to that of full-length tumstatin. This study aimed to explore the mechanisms of the T7 peptide in the regulation of Ang2 expression in endothelial cells (ECs) as well as inhibition of angiogenesis and invasion of hepatocellular carcinoma cells. We also examined the role of autophagy in angiogenesis. Human umbilical vein endothelial cells (HUVECs) were incubated with endothelial cell medium (ECM)-2 in a hypoxia chamber to mimic hypoxic conditions. The recombinant T7 peptide inhibited the cell viability, tube formation and induced apoptosis of the HUVECs. The T7 peptide downregulated the protein expression of Ang2 by inhibiting phosphorylation of AKT under hypoxic conditions. The migration of HUVECs and invasion of HepG2 cells were inhibited by the T7 peptide via inhibition of Ang2 expression. EC autophagy was induced by the T7 peptide. Inhibition of autophagy enhanced the anti‑angiogenic activity of the T7 peptide by increasing EC apoptosis. In vivo, immunohistochemistry of VE-cadherin and CD31 showed that angiogenesis was decreased significantly by the T7 peptide in a nude mouse xenogeneic tumor model. In conclusion, the T7 peptide inhibited angiogenesis and exerted its antitumor effects by inhibition of Ang2, phosphorylation of AKT and matrix metalloproteinase-2 (MMP-2) regulated by Ang2. Furthermore, inhibition of autophagy may significantly enhance the anti-angiogenic activity of the T7 peptide.