Targeting tumor and its microenvironment using nanotherapeutics for pancreatic cancer

摘要

ABSTRACT Pancreatic cancer (PC) is lethal with a five-year survival rate of less than 9.2 % and a median survival of 5-6 months. The limited efficacy of mono-therapies has led to the exploration of combination therapies with limited success because of challenges associated with dose-limiting side effects, drug-associated toxicities, drug resistance, and poor pharmacokinetics. Importantly, these past approaches have not attempted the concurrent targeting of the pancreatic tumor and its stroma and PC stem cells. Our proposed work addresses these challenges by determining functional and clinic-pathological significance of miR-345 as well as developing a dual delivery nanoscale device (DDND) for combined delivery of miR-345 and GEM for the treatment of PC. Our preliminary studies have shown that miR-345 targets several important genes, including sonic hedgehog (Shh), Kras, MUC4 mucin and its downstream targets, genes-associated with cancer stem cells (ALDH1, ESA, Hif1α, and Oct/3/4), and causes up regulation of cleaved caspase-3, -7, and PARP. The Kras, Shh and MUC4-signaling play critical roles in tumor growth and metastasis by promoting epithelial to mesenchymal transition (EMT), PC stem cells, angiogenesis, desmoplasia, which limit the delivery and efficacy of chemotherapy. MiR-345 targeting Kras, Shh and MUC4, which makes miR-345 is an excellent candidate for diagnostic/prognostic and therapeutic targets in PC. We hypothesize that downregulation of miR-345 contributes to PC pathogenesis by upregulation of Kras, SHH, and MUC4; Its restoration, combination with GEM through the DDND, enhances GEM sensitivity in PC through modulation of SHH/Kras/MUC4 pathways, resulting in inhibition of desmoplasia, pancreatic stellate cells, and PC stem cells leading to an improved therapeutic outcome of GEM in PC through improving its tumor perfusion. The DDND is based on temperature and pH responsive pentablock copolymers electrostatically complexed with miR-345 and subsequently self-assembled with GEM encapsulated layers. The DDND design allows effective co-incorporation of miRNA/GEM combination; facilitates cellular entry; enhances stability compared to liposomal carriers; provides miRNA protection; allows targeting by selectively facilitating endosomal escape in cancer cells as opposed to normal cells by exploiting intracellular pH differences; and allows dose- sparing of the cytotoxic drugs. Aim 1 will focus to determine functional role and clinico-pathological significance of miR-345/Shh/Kras/MUC4 axis in highly aggressive and metastatic PC. Aim 2 will focus on the development of DDND loaded miR-345/GEM as a novel therapeutic agent against lethal PC by evaluating their therapeutic efficacy in vitro. In the final Aim 3, we will evaluate therapeutic efficacy of DDND loaded miR-345/GEM alone or in combination in mouse models. Altogether, the proposed work decipher the clinic-pathological significance of miR-345 and expected to significantly advance the goal of combining GEM and miR-345 delivery for treatment of PC patients, enhance understanding of the synergistic mechanisms involved, and will provide a novel DDND design for delivery of other therapeutics as well in the future.