Antiangiogenic therapy enhances the efficacy of transcatheter arterial embolization for hepatocellular carcinomas

Establishment of a CBRH7919 cell line expressing rat IL-2 and B7-1

AIM: To establish a CBRH7919 cell line CBRH7919 expressing rat IL-2 and B7-1 genes and to examine their ability to express the IL-2 and B7-1 genes in vitro.

METHODS: The IL-2 and B7-1 genes were amplified by RT-PCR and subcloned into retroviral vectors pBaBe-puro and pMSCV-neo, respectively, to obtain the recombinant retroviral vectors pBaBe-puro-IL-2 and pMSCV-neo-B7-1. The recombinant plasmids were then transfected into the 293FT packaging cells. The obtained infectious viruses were used to infect the CBRH7919 cell line, and puro/G418-resistant clones were acquired after puro/G418 selection. The expression of IL-2 and B7-1 was detected using Q-PCR, Western blot and ELISA.

RESULTS: The rat IL-2 and B7-1 genes were successfully amplified by RT-PCR, and the recombinant plasmids pBaBe-puro-IL-2 and pMSCV-neo-B7-1 were successfully constructed and verified by direct sequencing. A CBRH7919 cell line (CBRH7919/IL-2/B7-1) expressing rat IL-2 and B7-1 was established. Q-PCR analysis showed that the expression levels of IL-2 and B7-1 mRNAs in CBRH-7919/IL-2/B7-1 cells were 4.15 and 17.04 times higher than those in CBRH-7919-pmscv-neo cells. Western blot analysis showed that the expression level of B7-1 protein in CBRH-7919/IL-2/B7-1 cells was 3 times more than that in unmodified cells, while ELISA showed that expression level of IL-2 was 190 times more than that in unmodified cells.

CONCLUSION: A CBRH7919 cell line stably and effectively expressing rat IL-2 and B7-1 genes was obtained and provides a good basis for further research of immuno-gene therapy of liver cancer.

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.

Experimental evaluation of inhibitory effect of 10-hydroxycamptothecin on hypoxia-inducible factor-1α expression and angiogenesis in liver tumors after transcatheter arterial embolization

PURPOSE

To evaluate the effect of transcatheter administration of 10-hydroxycamptothecin (HCPT), a hypoxia-inducible factor-1α (HIF-1α) inhibitor, on HIF-1α expression and angiogenesis in liver tumors after transcatheter arterial embolization in an animal model.

MATERIALS AND METHODS

VX2 tumors were implanted in the livers of 30 rabbits. The animals were divided randomly into three groups of 10 animals each. Group 1 animals received hepatic intraarterial infusion of distilled water. Group 2 animals received iodized oil infusion followed by embolization with 150-250 μm of polyvinyl alcohol particles. Group 3 animals received infusion of a mixture of HCPT (1 mg/kg body weight) with iodized oil followed by the particle embolization. Six hours or 3 days after transcatheter treatment, the animals were sacrificed, and the tumor samples were harvested. Immunohistochemical staining was performed to evaluate the levels of HIF-1α and vascular endothelial growth factor (VEGF) protein as well as microvessel density.

RESULTS

The levels of HIF-1α and VEGF and microvessel density in tumors of group 2 were significantly higher than those of group 1 or 3 (P < .05). However, no significant differences were noted in tumors between group 1 and 3 (P > .05). HIF-1α levels were significantly correlated with VEGF levels (r = .587, P = .001) and microvessel density (r = .527, P = .003).

CONCLUSIONS

Transcatheter infusion of HCPT has an inhibitory effect on HIF-1α expression and angiogenesis in liver tumors after transcatheter arterial embolization.

Combined approach to hepatocellular carcinoma: a new treatment concept for nonresectable disease

Depending on tumor burden, hepatic function and patients' performance status, hepatocellular carcinoma is treated by surgery, local procedures, systemic therapy or palliation. The majority of patients are diagnosed at a stage where local therapy is the treatment of choice. Recently, the multikinase inhibitor sorafenib was found to improve the survival of patients with advanced hepatocellular carcinoma and conserved liver function. In this manuscript, we summarize the experimental evidence supporting the combination of a systemic targeted therapy with a local therapy. We also discuss the pros and cons of different schedules of combining such treatments. We conclude that there is enough of a theoretical argument to design clinical trials testing this strategy.

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.

TACE versus TAE as therapy for hepatocellular carcinoma

Transarterial chemoembolization (TACE) improves survival in cirrhotic patients with hepatocellular carcinoma (HCC). The optimal schedule, best anticancer agent and best technique are still unclear. TACE may not be better than transarterial embolization (TAE). HCC is very chemoresistant, thus embolization may be more important than chemotherapy. Lipiodol cannot be considered as an embolic agent and there are no data to show that it can release chemotherapeutic agents slowly. It can mask residual vascularity on CT imaging and its use is not recommended. Both TACE and TAE result in hypoxia, which stimulates angiogenesis, promoting tumor growth; thus combination of TACE with antiangiogenic agents may improve current results. To date, there is no evidence that TACE pre-liver transplantation or resection helps to expand current selection criteria for patients with HCC, nor results in less recurrence after surgery. Combination with other techniques, such as radiofrequency ablation and drugs, may enhance the effect of TACE. New trials are being conducted to clarify these issues.