Formation of Immunoliposomes used for the Targeted Delivery of Mutant KRAS siRNA for the treatment of Pancreatic Cancer

Abstract:

Pancreatic cancer is one of the dangerous and deadliest forms of cancer diagnosed in cancer patients worldwide. Pancreatic ductal adenocarcinoma (PDAC) being the most common among different This increase in the mortality rate is mainly because of the lack of early symptoms and early detection of the disease. Gemcitabine along with cetuximab has been the standard form of therapy for the cancer patients but it is still far from the optimal and novel therapy which is required for this disease. Hence, there is a need for the development of a novel drug treatment. Mutations in the Kras gene has been found in about 90% of the pancreatic cancer case and is the major source for the malignancy. Thus, the goal of this study is to investigate the silencing of this gene which will eventually inhibit the pancreatic tumor growth. In order to this, I combined the k-ras small interfering RNA (siRNA) with the lipid molecule to increase the stability of siRNA, which in turn is associated with an anti-EGFR antibody. The pancreatic cells overexpress many protein receptors like the epidermal growth factor receptor (EGFR) so the anti-EGFR antibody will target the siRNA/liposome complex to the target the tumor cells. The liposomes are PEGylated so as to increase the circulation time and effective delivery of the drug target system. This cargo will be tested both in-vitro and in-vivo to evaluate the silencing of the desired gene.

Objective: Development of liposomal-based targeted siRNA delivery for the treatment of pancreatic cancer.

A. Specific aims

This project aims to design an effective drug delivery system for pancreatic cancer combining multiple strategies. Pancreatic cancer arises because of the genetic and accumulated alternations (1, 2). It is well known that the most common type of genetic mutation abnormality in pancreatic adenocarcinomas is the kras mutation (3). In 70-90% of the cases point mutation occur in k-ras gene, the majority occurring at codon 12 of oncogene (4,5). Therefore, efforts have been made to define the function of Ras in normal and diseased cells and to target ras for cancer therapy.

KRAS being a GTPase is activated by GTP and deactivated by GDP. The activated Kras binds and thus activates the RAF family kinases, BRAF, ARAF and RAF1(6). Activated RAFs is responsible for phosphorylating and activating ERK1 and ERK2 kinases. Later ERK phosphorylates nuclear and cytoplasmic transcription factors like ELK1 and c-JUN which leads to cell proliferation. Therefore, the mutation which causes the activation of K-ras leads to uncontrolled cell growth which eventually leads to cancer development and spreading (7). SiRNA will be used as a therapeutic drug to suppress KRAS expression. This siRNA mediated reduction in the expression of mutated KRAS in the pancreatic cells can reduce cell proliferation thus reducing the tumor growth (8, 9). Thus, to make sure that siRNA will preferentially target the cancer tissues rather than the normal tissues, cancer-specific antibody can be used for targeting purpose. One of the trait seen in cancer is that there is an overexpression of certain protein receptors on the cell surface. Pancreatic cancer cells have high expression of Epidermal Growth Factor Receptor (EGFR), which can be used as a drug delivery target against pancreatic cancer cell lines. Hence, the targeting moiety (anti-EGFR antibody) will be attached on the surface of liposomes to target specific cancer cell delivery.