大鼠部分肝切除之肝臟再生的探討 (一) 水通道蛋白於肝臟再生的表現 (二) Thalidomide對肝再生的影響

Abstract

The remarkable ability of liver to regenerate after insults has been harnessed by surgeons when designing techniques for liver resection or transplantation. However, the underlying mechanisms of liver regeneration are not fully clarified. There are two parts in this study of liver regeneration. Part I is the investigation for the expression of aquaporins (AQPs) in liver regeneration. The investigation for the influence of thalidomide on the liver regeneariton is in Part II. Aquaporins (AQPs) are small transmembrane proteins with unexpected physiological roles in addition to water transport. For example, they play pivotal roles in cell migration, angiogenesis, and cell proliferation, events that are also occurred during liver regeneration. We thus examined the possible involvement of AQPs in this regenerative process. 70% partial hepatectomy (PH) rat model was employed. The temporal expression of various AQPs in the liver following PH was determined by semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and western blotting. The localization of AQPs was evaluated by immunohistochemistry. Results. As anticipated, AQP0, 8, 9, and 11 were detected mainly in hepatocytes; unexpectedly, Kupffer cells were observed to express AQP8 during a specific period of time in the regenerative process. AQP9 protein was shown to be expressed in a progressively enhanced pattern at early time points after PH. A transient expression of AQP11 in the nucleus of hepatocytes was observed. These findings suggest the possibility that AQP might be involved in the PH-induced liver regeneration. The treatment for hepatocellular carcinoma (HCC) still presents a major challenge in high recurrent rate. HCC is a hypervascular malignancy. Antiangiogenic therapy may be a potential adjuvant treatment for HCC. Thalidomide, a antiangiogenic agent, may inhibit VEGF induced angiogenesis and it was used for patients with advanced HCC. The present study was undertaken to investigate the effect of thalidomide on liver regeneration after hepatectomy. In this study, all rats subjected to 70% PH were divided to two groups, one treated with oral thalidomide (100mg/kg), the other not. Serial changes in hepatic microcirculation were evaluated by Laser Doppler flowmetry. The VEGF expression in liver tissue was assessed by immunohistochemical study and western blot analysis. Following PH, the liver regeneration rate increased markedly and reached a peak at 96 h in the two groups. Thalidomide did not affect the overall restoration of liver mass, although a delay in cell proliferation was observed. Prior to PH, the liver microcirculation in rats treated with thalidomide for 2 days was comparatively less than that in their corresponding controls; however, no significant difference between the two groups was detected at any time-point following PH. Western blotting showed that the expression of IL-6 and VEGF was upregulated by PH and the expression levels in the two groups were equal at all studied time-points. TNF-α increased in the regenerative liver of thalidomide treated rats; however, there was no significant difference of TNF-α between the two groups. The immunohistochemical staining revealed a waved pattern of VEGF expression which advanced from the periportal to pericentral area in both groups, but a slower advancement was detected in thalidomide-treated rats. In conclusion, thalidomide exerted no significant effects on the expression of TNF-α, IL-6 and VEGF and did not impair the overall restoration of liver mass in a rat model of 70% PH-induced liver regeneration, providing supportive evidence for its use as a adjuvant treatment modality for liver cancers after tumors resection.