Development of a rat model for orthotopic liver transplantation for hepatocellular carcinoma

Systematic revelation of the protective effect and mechanism of Cordycep sinensis on diethylnitrosamine-induced rat hepatocellular carcinoma with proteomics

Cordyceps sinensis (C. sinensis) has been reported to treat liver diseases. Here, we investigated the inhibitory effect of C. sinensis on hepatocarcinoma in a diethylnitrosamine (DEN)-induced rat model with functional proteome tools.In the DEN-exposed group, levels of serum alanine aminotransferase and aspartate aminotransferase were increased while C. sinensis application remarkably inhibited the activities of these enzymes. Histopathological analysis also indicated that C. sinensis could substantially restore hypertrophic hepatocytes caused by DEN, suggesting that C. sinensis is effective in preventing DEN-induced hepatocarcinogenesis.We therefore comprehensively delineated the global protein alterations using a proteome platform. The most meaningful changes were found among proteins involved in oxidative stress and detoxification. Meanwhile, C. sinensis application could attenuate the carbonylation level of several enzymes as well as chaperone proteins. Network analysis implied that C. sinensis could obviously alleviate hepatocarcinoma via modulating redox imbalance, protein ubiquitination and tumor growth-associated transcription factors.Our findings provide new insight into the potential effects of C. sinensis in preventing carcinogenesis and might help in developing novel therapeutic strategies against chemical-induced hepatocarcinoma.

Rho-associated kinase inhibitor reduces tumor recurrence after liver transplantation in a rat hepatoma model

Tumor recurrence after liver transplantation still remains a significant problem in patients with hepatocellular carcinoma. The small GTPase Rho/Rho-associated kinase (ROCK) pathway is involved in the motility and invasiveness of cancer cells. We investigated whether tacrolimus activated the Rho/ROCK signal pathway to promote the invasiveness of rat hepatocellular carcinoma cells. We also investigated whether the ROCK inhibitor Y-27632 suppressed tumor recurrence after experimental liver transplantation in a rat hepatocellular carcinoma model. Orthotopic liver transplantation was performed in hepatocellular carcinoma cell line McA-RH7777-bearing rats. Tacrolimus was administered to liver transplant rats and these rats were divided into two groups: the Y-27632-treated (10 mg/kg, for 28 days) group and the Y-27632-untreated group. Tacrolimus enhanced the cancer cell migration and stimulated phosphorylation of the myosin light chain (MLC), a downstream effector of Rho/ROCK signaling. Y-27632 suppressed the cancer cell migration and tacrolimus-induced MLC phosphorylation. Suppression of tumor recurrence after liver transplantation and significant prolongation of survival were observed in the Y-27632-treated rats in comparison with theY-27632-untreated rats. Tacrolimus stimulates the Rho/ROCK signal pathway to enhance the invasiveness of hepatocellular carcinoma, and the ROCK inhibitor Y-27632 can be used as a new antimetastatic agent for the prevention of tumor recurrence after liver transplantation.

Major hepatic resection may suppress the growth of tumours remaining in the residual liver

Little is known as to how hepatectomy is associated with the growth of hepatic tumours, which may reside in the remaining liver after curative resection for hepatocellular carcinoma. Using an intra-hepatic tumour implantation model in rats, the effects of hepatectomy on tumour growth in the remaining liver were investigated. On post-operative day 7, the tumour weight in the remaining liver following 30% hepatectomy was 0.321+/-0.058 g (mean +/- SD) which was significantly greater than that (0.245+/-0.040 g) in sham operations (P<0.05). However, the tumour weight (0.156+/-0.067 g) in the remaining liver following 60% hepatectomy was significantly lower than that in sham animals (P< 0.005). The number of TdT-mediated dUTP nick-end labelling (TUNEL) positive tumour cells was significantly increased in 60% hepatectomy as compared with the sham and 30% hepatectomy group. The mRNA expression of TGF-beta1, TNF-alpha and Fas in the tumour portion of 60% hepatectomy, was higher than that in 30% hepatectomy group. Plasma levels of TGF-beta1 were inversely correlated with intra-hepatic tumour weights. These results suggest that major hepatic resection may lead to an increased induction of apoptosis for the remaining hepatic tumour.

Effect of systemic cyclosporine on tumor recurrence after liver transplantation in a model of hepatocellular carcinoma

BACKGROUND

Long-term results after liver transplantation for hepatocellular carcinoma have been disappointing, largely because of the high recurrence rate. It is controversial whether the immunosuppressed state of the recipient contributes to this recurrence rate. We have developed a model in the rat system to examine the effect of immunosuppression on tumor recurrence after transplantation, as well as to evaluate other treatment strategies to decrease the recurrence rate.

METHODS

A 2-mm3 nodule of Morris hepatoma 3924a was implanted intrahepatically at day 0. At postimplant day 16, the animals underwent syngeneic orthotopic liver transplantation. Two treatment groups were established. Group I received saline injections subcutaneously for 2 weeks, while group II received subcutaneous cyclosporine injections at 3 mg/kg/day for 14 days. Animal survival, tumor recurrence rate, and sites of recurrence and number of pulmonary nodules were recorded.

RESULTS

Overall survival rate was reduced in animals receiving cyclosporine. The mean survival time was 74.4 days (SEM 6.39 days) in saline-treated animals and 50.4 days (SEM 7.63 days) in the cyclosporine-treated animals. The proportion surviving in group 1 was 47% and in group 2 was 18%. This difference in survival was statistically significant (P=0.025). The incidence of pulmonary nodules was increased in the cyclosporine-treated animals, and tumor recurrence in extrapulmonary sites was seen only in the cyclosporine-treated animals.

CONCLUSION

Results from this study suggest that cyclosporine has an adverse effect on tumor recurrence after transplantation. This model will be useful to further examine treatment strategies to improve the outcome of transplantation for hepatocellular carcinoma.

The outcome of liver transplantation at various times (70, 120, and 134 days) after the initiation of carcinogenesis in rats

The therapeutic results of liver transplantation for primary liver cancer have not been satisfactory. The high rate of recurrence appears to be due to the inadequate care taken in selecting the most appropriate candidates for orthotopic liver transplantation (OLT), the presence of circulating hepatocellular carcinoma (HCC) cells and micrometastases at the time of liver transplantation, and the tumor growth-promoting effects of immunosuppressive agents. We believe that HCC patients must be carefully staged in order to identify those most suitable for OLT. We therefore induced HCC in pure-strain rats by the oral administration of diethylnitrosamine (DEN) and studied the outcomes of liver transplantation at various time points (70, 120, and 134 days) after the initiation of carcinogenesis. The mean survival time (MST +/- SD) of the non-OLT control group (N = 14) was 18.2 +/- 5 days after Day 120. The survival time of the four rats in the OLT Day 120 group was 81.3 +/- 20.6 days after transplantation. One rat showing full weight recovery soon after transplantation survived for 97 days after transplantation and then succumbed to recurrence. The survival time of the four rats in the OLT Day 134 group was 7.3 +/- 5.0 days after transplantation. The survival time of the three rats in the OLT Day 70 group was 145.3 +/- 70.0 days after transplantation, with a maximum survival of 221 days until death. Significantly prolonged survival, as compared with that in the non-OLT group, was observed in the OLT Day 70 and OLT Day 120 groups (p < 0.01), while there was no significant prolongation in the OLT Day 134 group (NS). The timing of liver transplantation is a very important factor. Preoperative assessment of factors potentially affecting recurrence in HCC patients is imperative for selecting the most appropriate candidates for OLT. Careful selection of candidates for OLT should always be considered the key to successful liver transplantation (i.e., long-term survival) for patients with liver cancer.