Novel Self-assemble nanoparticles to inhibit cancer growth -effects on ER stress, autophagy, and multidrug resistance by a small molecule

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Author:
Chen, Xiangyun
Graduate Program:
Molecular, Cellular and Integrative Biosciences
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
October 07, 2015
Committee Members:
  • Yanming Wang, Dissertation Advisor
  • Douglas Cavener, Committee Chair
  • Zhi Chun Lai, Committee Member
  • Lu Bai, Committee Member
  • Gavin Peter Robertson, Special Member
Keywords:
  • Nanomedicine
  • Multi-drug resistance
  • cancer
Abstract:
Drug resistance remains challenging for modern cancer therapy methods including surgery, radiation, and small molecule chemotherapy. Nanotechnology has emerged as promising strategy to overcome impasses in several science branches. Liposome, polymer sphere, carbon nanosphere, and metallic particles have been used for nanomedicine development. Doxil, pegylated liposomal doxorubicin, is the first FDA approved nanodrug to treat cancers in 1995. Doxorubicin is believed to confer cytotoxicity to cancer cells by 1) intercalation in DNA to disrupt topoisomerase II-mediated DNA repair and 2) generating free radicals to damage cell membrane, DNA, and proteins. Compared to free doxorubicin, Doxil greatly improves the pharmacokinetics of doxorubicin, reduces cardiotoxicity, and increases efficacy by passive targeting. However, Doxil is constantly on FDA’s shortage list. Due to manufacture complexity, even the FDA approved generic “Doxil” is costly to make. Therefore, I want to invent a high efficient and low toxicity nanomedicine that is simple to prepare and easy to scale up. In this dissertation, I present a novel strategy for preparing nanoparticles that are effective for drug resistant cancers. Among a series of β-carboline derived small molecules, Nano-6E kills cancer cells in micromolar range while is safe for normal human fibroblast (NHF) cells. Nano-6E accumulates more and/or metabolizes slower in cancerous U2OS cells compare to NHF cells. In addition, Nano-6E spontaneously assembles into nanoparticles. Nano-6E induces severe ER stress, disrupts cytoskeleton, and inhibits autophagy in U2OS cells. Interestingly, Nano-6E disturbs cytosolic calcium and affects autophagosome lysosome fusion. To achieve effective inhibition of multidrug resistant tumors, I combined Nano-6E with many clinical used anticancer drugs. Nano-6E and doxorubicin showed synergistic cytotoxicity to multi-drug resistant uterine sarcoma MES-SA/Dx5 cells. Dox-6E activates p53 and leads to apoptosis in MES-SA/Dx5 cells. Further investigation of Nano-6E and doxorubicin reveals that doxorubicin and Nano-6E forms dual-drug nano-particles range from 3.4 nm to 60.1 nm in diameters. The optimized size range enable Dox-6E particles to demonstrate enhanced permeation and retention effects, leading to 1) extend blood circulation time of doxorubicin; 2) accumulate more in tumor tissue and less in heart and kidney; and 3) significantly inhibit tumor growth in xenograft model of MES-SA/Dx5. In summary, I have designed a novel way to prepare nanoparticles adding another layer to current big molecular based nanotechnology. The self-assembled Dox-6E particles are high efficacy, low toxicity, and easy to prepare.