William Wei-Guo Jia
Relevant Degree Programs
Graduate Student Supervision
Doctoral Student Supervision (Jan 2008 - Mar 2019)
Despite excellent safety data, antitumor efficacy of the oncolytic herpes simplex virus type 1 (oHSV-1) in glioblastoma (GBM) patients is not satisfactory. A major enhancement of the oncolytic activity of the oHSV-1 is necessary to eradicate the GBM in clinics. To enhance the efficacy and tumour specificity, we first developed a GBM specific triple regulated oHSV-1 amplicon system (SU4-124 HSV-1). Translational regulation was achieved by incorporating five copies of microRNA 124 target sequences into the 3’UTR of the ICP4 gene. Additionally, a 5'UTR of rat fibroblast growth factor -2 was added in front of the viral ICP4 gene open reading frame. The SU4-124 HSV-1 demonstrated enhanced tumour specificity and stronger anti-tumour efficacy compared to the tumour non specific CMV- ICP4 HSV-1 in both in-vitro and in-vivo GBM models. We then examined the effect of a potent STAT inhibitor, which is the key regulator of interferon (IFN) response, nifuroxazide (NF), a prescription anti-diarrheal drug, on the oHSV-1 efficacy. This was done with the aim of reinforcing the anti-tumour efficacy of oHSV-1 and developing an effective combination therapy. Here, we found that NF synergistically augments the anti-tumour efficacy of oHSV-1 by regulating the anti-apoptotic properties of HSV-1 in various tumour cells. Moreover, our data demonstrated that STAT1/3 activation mediated the underlying cellular mechanism of this novel combination. To further improve the efficacy of oHSV-1, possible barriers in the microenvironment of GBM need to be identified. Since previous clinical GBM have documented an abundance of microglia /macrophages, we first investigated the interaction of oHSV-1 and microglia/macrophages in in-vitro and in-vivo GBM models. We found evidence that microglia/macrophages suppress oHSV-1 in glioma mass by generating a physical barrier to the dissemination of oHSV-1. We also observed that the deficiencies in viral replication in microglial cells are associated with the STAT1/3-mediated silence of particular viral genes. We found that an oxindole/imidazole derivative, C16, can aid the viral replication in microglia/macrophages and dramatically increase the therapeutic efficacy of oHSV-1 in GBM animal model. In conclusion, this project outlines possible ways to overcome the barriers involved in oHSV-1 therapy to successfully eradicate clinical GBM.
Prostate cancer is the most common non-skin cancer, and the second leading cause of cancer-death in men. Current treatments, including androgen withdrawal therapy, are not curative for advanced metastatic disease and new treatment strategies are urgently required. In this regard, oncolytic virotherapy offers a promising new approach. This project aims to provide a proof-of-principle that an oncolytic herpes simplex virus type-1 (HSV-1) virus can be engineered to replicate in a tissue- and tumor-specific fashion through both transcriptional and translational regulation of an essential viral gene. Using the amplicon/helper system, we first generated a prostate-specific amplicon virus by inserting the ARR2PB promoter in front of the ICP4 gene, and two tumor-specific amplicon viruses by incorporating multiple copies of miR-143 or miR-145 complementary target sequences in the 3’ untranslated region (3’UTR) of ICP4. Finally, we generated two prostate tumor-specific recombinant viruses using the bacterial artificial chromosome and the recombineering method. Our results showed that an amplicon system containing a prostate-specific promoter upstream of an essential viral gene can complement a helper virus for lytic replication specifically within prostate tumor cells. We also showed both in vitro and in vivo that viral replication and cell killing occurred only in tumor cells with abundant eIF4E protein or low levels of miR-143/miR-145 when viral gene expression was controlled by a modified 5’UTR or 3’UTR, respectively. Nude mice bearing LNCaP tumors treated with local or systemic injections of these tumor-specific viruses had a >85% reduction in tumor size at day 28 post-viral injection and without extensive toxicity to normal tissues. Quantitative real-time PCR analysis also showed that the majority of the virus was detected in the tumor mass and not within normal tissues. In conclusion, the incorporation of a tissue-specific promoter or a tumor-specific element in an oncolytic HSV-1 virus is a viable strategy to restrict viral replication and oncolysis selectively to tumor cells while sparing normal tissues. This work provides a basis for the development of novel oncolytic HSV-1 viruses for local and systemic treatment of locally advanced and metastatic prostate cancer.
Master's Student Supervision (2010-2017)
TDP-43 (TAR DNA binding protein 43) is a heterogeneous nuclear ribonucleoprotein(hnRNP) that has been found to be mainly responsible for neurodegenerative diseasesrecently. Its involvement in nuclear factor-kappaB pathways has been reported in neuron andmicroglial cells that are linked to amyotrophic lateral sclerosis (ALS). Nuclear factor-kappaB(NF-κB) is a family that consists of five members that exist and function as dimers. NF-κBpathway targets more than hundreds of genes that are involved in inflammation, immunityand cancer. It also has functions in the nervous system. p50/p65 (p50/RelA) heterodimers, asthe major Rel complex in the NF-κB family, are induced by diverse external physiologicalstimuli and modulate transcriptional activity in almost all cell types. Both p65 and TDP-43translocation are through the classic nuclear transportation system. In this study, we reportthat TDP-43 overexpression could block TNF-α induced p65 nuclear translocation dosedependently that further inhibits p65 transactivation activity. Furthermore, the inhibition byTDP-43 is not through preventing IκB degradation but probably by competing the nucleartransporter-importin α3 (KPNA4) and this competition is dependent on the presence of NLSin TDP-43. Silencing TDP-43 by a specific siRNA also increased p65 nuclear localizationupon TNF-α stimulation, suggesting that endogenous TDP-43 may be a default suppressor ofNF-κB pathway. The above results indicate that TDP-43 may play an important role inregulating the levels of NF-κB activity by control the nuclear translocation of p65.
20(S)-protopanaxadiol (aPPD) is a ginseng sapogenin and is claimed to be a promising anti-cancer drug candidate. Although bacterial biotransformation of ginsenosides in the gut has been thoroughly studied, few have reported on the metabolism of aPPD. As an orally taken xenobiotic, aPPD must first be absorbed and metabolized in the intestine before it reaches the liver for further metabolism. This thesis compares the metabolite profile and enzyme kinetic profile of aPPD in the human intestinal microsomes (HIM) and liver microsomes (HLM), respectively, and examines the interaction between aPPD and cytochrome P450 (CYP), an essential Phase I xenobiotic metabolizing enzyme. aPPD was incubated with HIM or HLM and NADPH regenerating system. Although we did not perform any detailed NMR structural analysis, three major mono-hydroxylated metabolites and five di-hydroxylated metabolites were identified in HIM and HLM using liquid chromatography mass spectrometry in positive ionization mode. A multiple reaction monitoring method, with m/z 477>459 and 459>441 transitions for mono-hydroxylated metabolites M1-M3, m/z 493>457 and 493>475 transitions for di-hydroxylated metabolites M4-M8, and m/z 443>425 and 425>123 transitions for aPPD, was established for subsequent kinetic study and reaction phenotyping study. aPPD metabolites formation in HIM have a much lower Km value than in HLM. Reaction phenotyping was performed with a panel of specific CYP chemical inhibitors and human recombinant CYP enzymes. CYP3A inhibitors, ketoconazole and troleandomycin, inhibits aPPD monohydroxyl metabolite formation in both HIM and HLM in a concentration dependent manner. Among the human recombinant CYP enzymes assayed, CYP3A4 showed the highest activity in aPPD monohydroxyl metabolite formation followed by CYP3A5. In summary, this study suggests that CYP3A isoforms are the predominant enzymes responsible for aPPD mono-hydroxylation in HLM and HIM.