published_or_final_version / Pathology / Doctoral / Doctor of Philosophy

With the recent advances in the knowledge of hepato-carcinogenesis, there has been encouraging development in the molecular targeted therapy for patients with advanced hepatocellular carcinoma (HCC). Sorafenib, an anti-angiogenic multi-targeted receptor tyrosine kinase inhibitor, has become the standard of treatment in HCC patients with Child-Pugh A cirrhosis. Nevertheless, the benefits and safety profile of sorafenib in the majority of the unselected advanced HCC patients and other patient subgroups are still unclear. More importantly, the survival benefit associated with sorafenib use is generally modest in Asian population. Therefore, an unmet medical need remains for more effective therapeutic agents. This thesis studied the impact of molecular targeted therapy in the treatment of advanced HCC patients and it contains 10 original studies divided into six sections. The first section provides a concise overview of the epidemiology, risk factors, and current treatment options for HCC patients. Also, the molecular biology and opportunity for the use of targeted therapy in advanced HCC were discussed. The second section is about a new prognostic score system that we developed — Advanced Liver Cancer Prognostic System (ALCPS). Our study results showed that ALCPS was able to objectively estimate the 3-month survival probability of advanced HCC patients and thus could enhance patient selection for targeted therapy or clinical trials. The third section is about the use of sorafenib in the treatment of advanced HCC patients. The results of our single centre phase II study showed that sorafenib had good efficacy and acceptable tolerability in treating advanced HCC patients in hepatitis B endemic area. Furthermore, our retrospective study results confirmed that the overall survival benefits and overall treatment-related adverse events of sorafenib were comparable in elderly and young advanced HCC patients. More importantly, our other retrospective analysis showed that Child-Pugh (CP) A and CP B patients tolerated sorafenib similarly and derived similar clinical and progression-free survival benefit. Among CP B patients, most benefits were observed in patients with score 7. Nevertheless, CP B patients were more susceptible to developing cirrhotic complications. Last but not least, our study also demonstrated that drop in serum alpha-fetoprotein level > 20% in the first 6 weeks of sorafenib treatment was a useful early surrogate endpoint for evaluating antitumor response and survival benefits. All these results are instrumental in guiding future rational use of sorafenib in advanced HCC population. The fourth section is about the role of targeted therapies in treating sorafenib-refractory advanced HCC patients. In a single arm phase II study, we showed that bevacizumab and erlotinib combination was not effective in treating advanced HCC patients who had failed prior sorafenib treatment. The fifth section of the thesis comprises results of four early phase novel clinical trials that may potentially improve the therapeutic outcomes in advanced HCC patients. First, our phase I/II study demonstrated that another anti-angiogenic agent — PTK787 had encouraging and possible synergistic activity when combined with intravenous doxorubicin in treating advanced HCC patients. Second, our multi-center phase II study results demonstrated promising activity with good tolerability of a novel combination — sorafenib together with capecitabine and oxaliplatin (SECOX) in the treatment of advanced HCC patients. Third, in a phase I study, we showed that pazopanib, a novel anti-angiogenic agent, had a manageable safety profile and preliminary activity in advanced HCC patients. Moreover, pazopanib reduced tumor vessel leakage, as shown by contrast-enhanced magnetic resonance imaging indicating a direct effect on HCC vasculature that might be associated with its antitumor activity. Lastly, in another phase I study, we evaluated safety, pharmacological parameters, and potential antitumor activity of pegylated recombinant human arginase 1 (peg-rhArg1) in advanced HCC patients. Our results illustrated that arginine depletion in humans can be achieved safely with peg-rhAgr1 in a dose-response manner and peg-rhArg1 had manageable safety profile and preliminary evidence of activity in advanced HCC patients. In the last section, the future perspectives about the use of molecular targeted therapy in the treatment of advanced HCC patients were discussed. / published_or_final_version / Medicine / Master / Doctor of Medicine

Hepatocellular carcinoma (HCC) is the major type of primary liver cancer which is well-known for its high heterogenicity and metastatic potential. Despite of the current advancement in surgical resection and the availability of targeted therapy, HCC remains a barely curable and fatal disease. We previously demonstrated that deregulation of epigenetic regulators is a common event in human HCC. Herein, we identified the frequent up-regulation of the prototype of H3K9 tri-methyltransferase SUV39H1 in clinical HCCs. SUV39H1 over-expression was also significantly associated with increased Ki67 expression and the presence of venous invasion. By using both SUV39H1 over-expression and knockdown model, we consistently demonstrated that SUV39H1 contributed to HCC tumor growth and migration. Most importantly, SUV39H1 knockdown drastically suppressed in vivo tumorigenicity and extra-hepatic metastasis of HCC cells in nude mice model. These findings evidently demonstrated the oncogenic role of SUV39H1 in HCC and implied potential therapeutic targeting of SUV39H1 for HCC treatment. Molecularly, SUV39H1 knockdown HCC cell underwent morphological changes and accompanied with increased lysosomal β-galactosidase activity and elevated p21 protein and γH2AX level. This data suggested senescence induction in SUV39H1 knockdown HCC cells. SUV39H1 has been implicated in telomere regulation and transcriptional control. However, neither telomere length nor expression of tumor suppressor genes was altered in SUV39H1 knockdown HCC cells. Interestingly, we demonstrated a novel observation that SUV39H1 may potentially methylate non-histone substrates that are yet to be identified, which may contribute to the pro-tumorigenic function of SUV39H1 in HCC. We also investigated the upstream regulation of SUV39H1 and identified miR-125b as the negative post-transcriptional regulator of SUV39H1. Ectopic expression of miR-125b abolished SUV39H1 3’UTR-coupled luciferase activity and suppressed endogenous SUV39H1 at both mRNA and protein level. Clinically, miR-125b level was found inversely correlated with SUV39H1 expression. We have previously reported the frequent under-expression of miR-125b in HCC. Collectively, our data suggested that SUV39H1 up-regulation in HCC may be the sequential outcome of miR-125b down-regulation. In conclusion, we demonstrated for the first time that SUV39H1 up-regulation contributed to HCC development and metastasis, potentially via senescence evasion. SUV39H1 elevation in HCC was attributed to the loss of its negative regulator, the tumor suppressive miR-125b. / published_or_final_version / Pathology / Doctoral / Doctor of Philosophy

Background and Aim Hepatocellular Carcinoma (HCC) is the fifth most frequent malignancy worldwide with high mortality and recurrence rate. Chronic inflammation is a dominant risk factor for the malignancy and the roles of tumor associated immunological infiltrates during the disease development and progression remain unclear. The significance of alternative activated macrophages (M2) with pro-tumor phenotypes has been demonstrated in many cancers except HCC. M2 macrophages are associated with tumor angiogenesis, invasion and growth which represent a potential target to be investigated. In this study, we intend to investigate the role of M2 macrophage on HCC. Materials and Methods M2 macrophages in 100 clinical specimens collected from HCC patients were detected by immunohistochemical (IHC) staining and quantitative PCR using common macrophage markers CD14 and CD68, and M2 specific markers CD163, Scavenger receptor class A (SA) and Mannose receptor (MR). The protein and transcript expression levels were further correlated with clinical pathological parameters. Phenotypic and functional characteristics of M1 and M2 macrophages derived from THP-1 cell line were validated and their roles in promoting HCC growth and invasion were studied in vitro co-culture system and in vivo orthotopic mice model. Secretory profiles of M2 macrophages after cocultivated with HCC cells were analyzed by cytokines antibody array screening. C-C motif chemokine 22 (CCL22) was identified to be upregulated in M2 macrophages in response to HCC cells. The functional roles of the chemokine in HCC was further studied by chemotaxis and migration assay. Underlying molecular mechanisms induced by CCL22 in HCC cells were determined. Results In clinical analysis, we first discovered that macrophages were widely expressed in liver tumor comprising 10-30% of total cell population. Noteworthy, the density of a M2 macrophage marker CD163 was found to had a significant prognostic impact as an independent factor associated disease free survival (HR: 3.79; 95% CI 1.3-10.4; p<0.01). Strong expression of the CD163+ population was also correlated with poor relapse free survival, multiple tumor nodules and increased venous infiltration. In vivo studies revealed that the tumor volume injected with M2 macrophages increased 3.26-fold (1.27cm3±0.36) compared to the control group (0.39cm3±0.05) (P=0.032). In contrast, mice injected with M1 macrophages had a significant reduction of tumor volume by 2.79-fold (0.14cm3±0.02) (P=0.044). Increasing rate of lung metastases (57%) was also observed in M2 treated group compared to the control (25%) (P<0.05). In vitro, M2 macrophages increased the number of HCC cells (MHCC97L) and migration events by 1.3-fold and 3.2-fold after cocultivation compared to negative control (P<0.05). In cytokine antibody array study, M2 macrophages derived CCL22 was discovered to be strongly induced by MHCC97L. Chemotaxis analysis confirmed that CCL22 increased MHCC97L migration capacities and excess level led to increased venous infiltration in HCC patients (p<0.05). Upon addition of CCL22, the epithelial mesenchymal transition through SNAIL activation in MHCC97L was observed. Conclusion Clinical analysis and both the in vitro and in vivo studies presented here collectively illustrated the significances of M2 macrophages in promoting tumor growth and migration through CCL22-CCR4 mechanism in HCC. Targeting these M2 macrophages and associated products in situ represents a novel approach for treating the disease. / published_or_final_version / Surgery / Doctoral / Doctor of Philosophy

Hepatocellular carcinoma (HCC)is one of the commonly diagnosed cancers in the world. Most patients have poor prognosis due to late detection of disease. Ankyrin repeat and suppressor of cytokine signaling box protein 4(ASB4), as a member of the ASB family, possesses two domains, ankyrin repeat (AR) and suppressor of cytokine signaling (SOCS)box, which are responsible for recruiting the target proteins for proteasomal degradation. Previous study has demonstrated high expression level of ASB4 in metastatic HCC cells, implicating the properties of ASB4 in cancer invasiveness. With this hypothesis, various experiments were performed in this research project to elucidate the functional roles of ASB4 in HCC cells. The aim of this study is to characterize the roles of ASB4 in HCC by manipulating its expression level in HCC cell lines through gene knockdown and over-expression. Altering the level of ASB4 in HCC cells resulted in no significant effects on the cell proliferation rates. However, ASB4 was demonstrated to promote migration and invasion properties of HCC cells, as suppression of its level led to slower migration and made cells less invasive. Opposite effects on cell migration and invasion were observed when ASB4 was ectopically expressed. Regarding the regulatory mechanism of ASB4, miR-200a was demonstrated to be a negative regulator for ASB4. In summary, ASB4 is probably involved in the migration and invasion properties of HCC cells, and also, being regulated by miR-200a. / published_or_final_version / Surgery / Master / Master of Philosophy

Hepatocellular Carcinoma (HCC) the fifth most common cancer and the third leading cause of death among cancer worldwide. Curative treatments such as liver resection and liver transplantation are generally used in treating early-stage HCC patients. However, only 10% to 30% of HCC patients are eligible for the surgery, which is due to the asymptomatic characteristic of HCC, most HCC patients are diagnosed at late stage. Palliative treatment such as TAE, TACE and Sorafenib provide them options to maintain their quality of life and extend their survival. Nevertheless, current treatments provides limited benefits to them as efficacy remains unsatisfactory. Therefore, there is a great need to develop new palliative treatments and explore new agents for the treatment of HCC. The aim of this study is to investigate the efficacy of a new therapeutic agent, Ombrabulin, in the treatment of HCC. Angiogenesis in HCC has been well-studied for many years as many studies proved that angiogeneisis plays an important role in the progression and development of HCC. Angiogenesis can also affect the prognosis and efficacy of treatments in HCC. As a result, antiangiogenesis and vascular disrupting agents have become new target in the therapaies of HCC. Ombrabulin is a synthetic vascular disrupting agent, which can inhibit tubulin polymerization in endothelial cells, causing cytoskeleton disorganization in endothelial cells. Endothelial cells will then detach from the basement membrane and eventually lead to vascular shutdown. This study demonstrated for the first time that Ombrabulin could selectively inhibit human umbilical vein endothelial cell (HUVEC) growth in vitro; particularly the early-form of HUVEC, which represent immature endothelial cell in neovasculature. Furthermore, this study also demonstrated the antiangiogenic effect of Ombrabulin on endothelial cells. By F-actin staining, it was shown that Ombrabulin caused changes in HUVECs morphology, which supported that Ombrabulin could lead to distortion in cytoskeleton. In vivo study demonstrated the early effect and long term effect of Ombrabulin. For the first part of the in vivo study, Nude mice were treated with single-dose of Ombrabulin for one week. Hoechst 33342, anti-CD34 staining and PCNA staining were carried out to study the functional effect of Ombrabulin and the combination effect with Sorafenib in vivo. Mice treated with Ombrabulin resulted in decreased blood perfusion, microvessel density and tumor cell proliferation, and tumor necrosis was also observed. In the combination with Sorafenib, it did not show synergistic effect in both tumor cell proliferation and microvessel density. For the second part of the in vivo study, nod scid mice were treated with multiple doses of Ombrabulin for three weeks to study the long term effect of Ombrabulin. Mice treated with Ombrabulin resulted in significantly smaller tumor size, demonstrating its antitumor efficacy in HCC. Furthermore, combination treatment of Sorafenib and Ombrabulin in vivo could enhance the efficacy of the treatment of HCC. In conclusion, Ombrabulin has vascular disrupting and antitumor effects, which could efficiently suppress HCC tumor growth in vivo. These results suggest that Ombrabulin could be a promising vascular disrupting agent in treating HCC. Combination with sorafenib should be further explored in clinical studies to demonstrate the synergistic antitumor effects in HCC patients. / published_or_final_version / Surgery / Master / Master of Philosophy

abstract / Anatomy / Doctoral / Doctor of Philosophy

published_or_final_version / Medicine / Master / Doctor of Medicine

published_or_final_version / Medicine / Master / Doctor of Medicine

published_or_final_version / Surgery / Doctoral / Doctor of Philosophy