Research Of Multifunctional Nanoparticle In Liver Cancer Theranostics

Liver cancer is one of the most common malignancies with a rising incidenceand mortality in our country. Over the past decade, advances in combinationof hepatectomy, adjuvant chemotherapy and percutaneous ablation have resulted inconsiderable improvements in therapy of liver cancer. However, most of these fail toincreased long-term survivals of patients. Undetected onset, long incubation period,high malignant degree and rapid development of most primary liver cancer patientsare major limitations for early diagnosis, while multidrug resistance, frequentrecurrence and a high incidence of metastasis after treatment have made the overallprognosis unsatisfactory and ultimately leads to death. Therefore, early accuratediagnosis, targeted drug delivery and reduction of systemic side effects of treatmentbecome current and challenges of diagnosis and treatment of liver cancer. In recentyears, the rise of nanotechnology will facilitate cracking this hard nut, whilethe fusion of nanotechnology and medicine has led to the emergence of nanomedicine,which become one of the most clinically translated interdiscipline. There has been anunprecedented expansion in the field of nanomedicine with the development of newnanoparticles, inorgannic nanoparticles have unique nano characteristics andbiological properties, which enable them to have high stability,high yield and low cost, thereby making them highly attractive in many aspects ofcancer diagnosis and therapy. Amajor goal in nanomedicine is the coherentimplementation of multifunctional nanoplatforms within targeted nanodelivery systemthat would simultaneously perform theranostics, the integration of diagnostics andtherapies. For inorganic multifunctional nanoplatforms to be effective in cancertheranostics, they must fulfill certain criteria:(1) The nanoplatform must package avariety of molecular imaging modalities to achieve early accurate diagnosis of cancer.(2) The nanoplatform must combine a variety of synthetic strategies to improving therapeutic efficacy, as well as reducing systemic side effects.(3) The nanoplatformmust achieve real-time tracing targeted drug delivery, release and efficacy, along withthe individualized adjustment of drug selection and dosage. Taken together,sophisticated nanoplatform will offer the promise for tailor-made clinical toolsrequired for “personalized cancer medicine.” Based on this, my thesis aimed atimproving the effect of diagnosis and therapy of liver cancer, we focused on threeclinical challenges including difficulty in early diagnosis, severe side effects alongwith low chemotherapy efficacy, and poor targeting of gene therapy. With thedevelopment of intelligent molecular design, nano-characteristic control and targetedsurface modification, we employed inorganic nanoparticles including quantum dotsand magetic mesoporous silica to fabricated effective and safe nanoplatform, whichload drugs and contrast agents for liver cancer theranostics. Furthermore, with suchsophisticated nanodrug for targeted gene therapy and chemotherapy are conceivable,making it possible to real-time monitor targeted drug delivery and release, as well asevaluate therapeutic efficacy and systemic side effects. The main results weresummarized below:(1) Exploring intracellular behavior of suicide gene is significant for improving theeffcacy and safety of herpes simplex virus thymidine kinase gene/ganciclovir(HSV-TK/GCV) system in cancer therapy. In this part, we have reported aquantum-dot-based technique for revealing the procedure of HSV-TK/GCV suicidegene therapy by constructing covalent linkage between fluorescent quantum dots(QDs) and TK gene. This stable QD labeling did not influence either the QDsfluorescence or the biological activity of TK gene. It is demonstrated that TK genewas shuttled to the nucleus after a-24h treatment; at that time the single dose of GCVadministration exerts the gradually increasing lethal effect until to72h. Real-timetracing the formation of liver cancer treated with HSV-TK/GCV suicide gene systemin vivo by QD-based NIR fluorescence imaging provides useful insight towardQD-based theranostics in future liver cancer therapy.(2) Developing traceable and safe therapeutic strategy may shed light on targeted genedelivery and personalized liver cancer therapy. In this part, we have combined an HSV-TK/GCV suicide gene system and near-infrared quantum dots, employing thatthe former is quite effective in liver cancer treatment and the latter facilitates tumorimaging. A folate-modified theranostic liposome (FL/QD-TK) was developed that iscomposed of an HSV-TK suicide gene covalently coupling with near-infraredfluorescent CdSeTe/ZnS core/shell quantum dots. The liver cancer-targeting andbiosafety of FL/QD-TK were studied in vitro and in vivo. FL/QDs-TK exhibited highspecific tumor imaging and strong inhibition on folate receptor-overexpressedBel-7402mouse xenografts without systematic toxicity, indicating that FL/QDs-TKhas potential advantages to overcome the problems of conventional suicide genetherapy and might be applied as a theranostic tool for real-time gene delivery andtherapy in liver cancer.(3) Controling the intrinsic toxicity of nanomaterials for anticancer therapy is anemerging concept. In this part, we have discovered that CdTe/CdS quantum dots,when coated with lipids (QD-LC) instead of popular lipids demonstratedextraordinarily high specificity for cancer cells, which was due to the difference in themacropinocytosis uptake pathways of QD-LC between the cancer cells and thenormal cells. QD-LC-induced HepG2cell apoptosis was concomitant with theactivation of the ROS-mediated JNK/caspase-3signaling pathway. Moreover, QD-LCtreatment resulted in a delay in the latent period for microtumor formation of mousehepatocarcinoma H22cells and inhibited tumor growth without systematic toxicity inmajor organs after intratumoral administrations to tumor-bearing mice. Our resultsprovide a proof-of-concept for the intrinsic toxicity of QD-based cancer therapystrategy, and demonstrated that QD-LC could be a very promising theranostic agentagainst liver cancer.(4) Employing multifuntional magnetic nanoparticles as nanocarrier to simultaneouslyload chemotherapy drugs and imaging agents have made theranostics a promisingstrategy for liver cancer treatment. In this part, we have engineered multifunctionalJanus nanocomposites integrated a magnetic Fe3O4head with mesoporous SiO2asnanocarrier (M-MSNs), which possess a uniform size with designable aspect-ratio andwell defined pore structures, as well as superior magnetic properties. The antitumor agent doxorubicin (DOX) was preload to the mesoporous silica via a pH-sensitivehydrazone bond to facilitate a selective cancer cell release, M-MSNs surface modifiedwith polyethylene glycol(PEG) acquired good bioavailability and biocompatibility,meanwhile, Fe3O4head was strongly responsive to the external magnetic field (MF).The novel nano-carrier(M-MSN-PEG) exhibited extraordinary endocytosis capacityin a dose-and time-manner, as well as MF response in several liver cancer cell linescomparing to normal liver cells. The nano-bullet M-MSN-PEG@DOX selectivelyinhibited cancer cell growth especially in MF environment, but has negligible killingeffect on human normal cells. This cancer targeting is mainly depended on thepH-sensitive DOX release and strong MF-induced endocytosis in cancer cells. In vivotransplanted tumor model and liver carcinoma in situ model in nude micedemonstrated that the Janus nano-bullets significantly reduced systematic toxicity andgreatly inhibited tumor growth. Taken together, this study illustrated the newtheranostic strategy in liver cancer treatment based on a novel Janus nano-bullets,aiming at optimizing therapeutic planning to achieve the most efficient and safe livercancer therapy.In summary, this thesis carried out an in-depth and system research in real-timemontoring liver cancer targeted suicide gene therapy, controlling the intrinsic toxicityof quantum dots for liver cancer selective therapy, as well as achieving the efficientand safe liver cancer therapy thanks to serveral multifuctionally inorganicnanoplatforms. All of our study sheds light on liver cancer theranostics in futurestudies to improve its effcacy and safety for clinical application and support futurepersonalized medicine.