Progesterone-cationic lipid conjugate-based nanoaggregates for cancer cell-selective delivery of drug and metal organic frameworks

Cancer is a deadly disease that leads to millions of deaths each year. While there are several modern treatment methods in use such as chemotherapy and gene therapy, they are held back due to severe side-effects and inefficient uptake into the cancer cells. Therefore, cancer-targeted vehicles for drug and nucleic acid delivery are needed. Towards this, several cationic lipid derivatives of known small molecules have been synthesized that show cancer-specific toxicity. In the same line, a progesterone-cationic lipid conjugate named PR10 was developed that also showed significant cancer-selective toxicity. However, it also showed a nanoaggregate formation property and an ability of the nanoaggregates so formed to be selectively taken up into cancer cells. The aim of this thesis is to further characterize the cancer-selective uptake of the PR10 nanoaggregates, followed by testing its ability to entrap and deliver either a drug (etoposide) or a plasmid-containing metal-organic framework (ZIF-8) selectively to cancer cells. For further development of this material, information regarding the mechanism of cancer-selective uptake is essential. Hence, in this thesis, it was attempted to identify the endocytic pathway involved in the uptake of PR10 nanoaggregates into cancer cells. Chapter 1 provides a summary of cancer where their types, causes and current therapeutic interventions are discussed. In this chapter the different cell death pathways present in the cells are also discussed. A basic overview of therapeutics based on nanotechnology is provided along with some of the FDA-approved nanotherapeutics. Then an overview of cationic lipids and their modifications towards therapeutic use are presented. In this works presented in this thesis, the progesterone-cationic lipid conjugate PR10 will be used. This molecule has been shown to have cancer-selective toxicity by earlier work done in our lab. Therefore, a summary of the work done will be provided in this chapter. Finally, the summaries of the present objectives are given. Overall, this chapter defines clear cut details of cancer and therapeutic interventions with a focus on chemotherapy, especially targeted chemotherapy. In Chapter 2, the endocytic pathway used in the cancer cell-selective uptake of PR10 nanoaggregates was evaluated. The most common endocytic pathways were chemically inhibited and the uptake of PR10 nanoaggregates was tested. The studies presented in this chapter clearly showed that the uptake of PR10 occurs predominantly through the macropinocytosis pathway, that is itself known to be overactive in cancer cells owing to their high nutrient demands. In Chapter 3, the possibility of using PR10 nanoaggregates as a hydrophobic drug delivery agent to deliver the drug etoposide and increase toxicity in etoposide-resistant cells was explored. The etoposide-entrapped PR10:etoposide (P:E) nanoaggregates indeed showed enhanced toxicity in etoposide-resistant colorectal cancer (CT26) and prostate cancer (PC-3) cells. It was also seen that P:E has the ability to downregulate the drug efflux protein ABCB1, possibly leading to the enhanced toxicity in CT26 cells. In Chapter 4, the complexation between PR10 nanoaggregates and ZIF-8 metal organic frameworks (MOF) was investigated. The ZIF-8 contains DNA, and the PR10 can act as a cancer targeting agent for the ZIF8 particles. It was seen that the PR10 complexation protects ZIF8 from a degrading environment that would otherwise prematurely damage the ZIF8 particles. Following this, an increased cancer-selectivity in the uptake of the PR10-ZIF8 complexes was observed. In Chapter 5, the work presented in Chapter 2-4 is summarized. Following this, the limitations of the work done and possible future directions are discussed. Taken together, the work presented in this thesis shows the possibility of using cationic lipid conjugates of small molecules such as progesterone in delivery of drugs to drug-resistant cells while enhancing toxicity, and in delivery of MOFs which can be used for the purpose of nucleic acid delivery.