Hepatocellular carcinoma (HCC) is one of the most prevalent cancers in the world and Taiwan. The major factors involved in the molecular pathogenesis for the development of HCC had been explored in recent years. An extensive array of growth factors and their receptors had been identified and may act as positive and negative modulators in different stages of hepatocarcinogenesis. Current therapeutic approaches for HCC include surgical resection (include liver transplantation), trans-arterial embolization (TAE), alcohol injection, etc. However, the effect is limited due to most of the HCC patients present with advanced stages of the disease. Therefore, this underscores the need for the development of novel therapeutic strategies. It is pivotal to set up an orthotopic hepatoma model for the development of novel intervention strategies for HCC. Under the guidance of ultrasound, we are able to create hepatoma in the liver lobe of Sprague-Dawley (SD) rats by injection of Novikoff (N1-S1) hepatoma cells. In addition, sonographic technique was employed for the monitoring of tumor growth in this animal model in the following subprojects. The continuous, non-invasive measurement of orthotopic hepatoma development will be a valuable tool for the evaluation of effects of drugs for treatment of HCC. In Chapter 1, the study employed a relatively non-invasive approach to establish an orthotopic HCC model in immune-competent rats. This was done by ultrasound-guided implantation of cancer cells and the model was used to evaluate the therapeutic efficacy of short-term and low-dose epirubicin chemotherapy. Ultrasound-guided implantation of Novikoff hepatoma cells led to the formation of orthotopic HCC in 60.4% of the SD rats. Moreover, tumor sizes measured by ultrasound significantly correlated with those measured by calipers after sacrificing the animals (P < 0.00001). The rate of tumor induction by ultrasound-guided implantation was comparable to that of laparotomy (55/91, 60.4% vs. 39/52, 75%) and no significant difference in sizes of tumor was noted between the two groups. Moreover, there was a significant correlation in tumor size measurement by ultrasound and computerized tomography. In tumor-bearing rats, short-term and low-dose epirubicin chemotherapy caused a significant reduction in tumor growth, and was found to be associated with enhanced apoptosis and attenuated proliferation as well as a decrease in microvessel density in tumors. In chapter 2, we investigated the chemopreventive effects of celecoxib in the growth of orthotopic rat HCC and the possible signal pathways involved. The status of COX-2 expression in rat Novikoff HCC was consistent with that in human HCC. Both Western blot and PCR tests had proved that N1-S1 was a HCC model presenting with low COX-2 enzymes in tumor cells. Then, low doses of celecoxib was shown to effectively inhibited the proliferation and increased the apoptosis of N1-S1 cells in vitro, which were also safe to the normal hepatocytes. Moreover, chemoprevention by celecoxib inhibiting the HCC tumor growth was shown in rat orthotropic HCC model. Tumor incidence was not affected by the celecoxib prevention, but, tumor weight was found significantly suppressed by the drug. Possible mechanisms of chemoprevention by celecoxib seen in the animal model were thought to be related to the anti-angiogenic, anti-proliferative and anti-hCSC characters of the drug. In chapter 3, we tried to test the combined inhibitory effects of low doses of celecoxib and epirubicin on the growth of HCC. Combined low doses of epirubicin and celecoxib was effective in inhibiting the hepatic cancer stem cells, tumor angiogenesis, tumor cell proliferation, as well as promoting cancer apoptosis. These are compatible with the effects of the individual drugs on HCC growth shown in the previous two chapters. In general, combination therapy expressed more effectiveness in tumor suppression and less bone marrow suppression than the individual drugs used alone. Taken together, ultrasound-guided implantation of Novikoff hepatoma cells is an effective means of establishing orthotopic HCC in SD rats, which is suitable and convenient for therapeutic trial of anti-HCC treatment. In the current study, we had proved the efficacies of low doses of two drugs, epirubicin and celecoxib, acting individually, as well as the combined effects of them in treating HCC in this model.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-1221110-155720 |
| Date | 21 December 2010 |
| Creators | Chan, Hoi-hung |
| Contributors | Ming-hong Tai, Xi-Zhang Lin, Ching-mei Hsu, Tsung-hui Hu, Jiin-tsuey Cheng |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-1221110-155720 |
| Rights | unrestricted, Copyright information available at source archive |
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