A novel regimen to target both pancreatic cancer K-ras and antiapoptotic proteins

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Abstract The goal of this R03 pilot project is to demonstrate a proof of concept for an innovative combination treatment regimen designed to target pancreatic cancer with K-ras mutations and aberrant expression of one or more antiapoptotic proteins. K-ras oncogenic mutations and aberrant expression of major antiapoptotic proteins (e.g. survivin, Mcl-1, XIAP, cIAP2) in pancreatic cancer heavily contribute to pancreatic cancer development and aggressiveness (treatment resistance, metastasis, and relapse). Gain-of-K-ras-function mutations is observed in >90% of pancreatic cancer patients. Genetic silencing of mutated K-ras induces apoptosis and inhibits pancreatic cancer cell growth, invasiveness, malignant tumor formation, and xenograft tumor growth. However, there are no effective targeted therapies available for pancreatic cancer K-ras mutations. Using a novel screening approach with K-ras mutant cells versus normal cells, fifteen chemical constituents from the medicinal plant Amoora rohituka were identified, and over 50 derivatives were generated using semi-synthetic approaches from the 15 hits. These compounds were then rescreened using K-ras mutant cells versus normal cells. AMR-Me and AMR-MeOAc were identified as the most potent compounds selectively against the K-ras mutant cells. Our previous studies indicated that AMR-Me targets the K-ras pathway, and that 3 mg/kg daily for 28-day treatment of mice shows no clear toxicity, while it extends leukemia mouse survival. We plan to combine AMR-MeOAc (best selectivity) with our novel compound, FL118, which selectively inhibits survivin, Mcl-1, XIAP, and cIAP2, for testing this novel combinational-targeted treatment regimen. It has previously been shown that combination of K-ras silencing with gemcitabine dramatically reduces tumor volumes in mice compared with either single agent alone. Therefore, we hypothesize that inhibition of both mutated K-ras and the major antiapoptotic proteins with the novel agents AMR-MeOAc and FL118 would lead to a strikingly enhanced induction of apoptosis and inhibition of pancreatic cancer cell and tumor growth than the inhibition from either agent alone. The following three specific aims are proposed in this project. Aim 1: Determine the efficacy of AMR-MeOAc in the presence or absence of low dose FL118 on pancreatic cancer cell growth, apoptosis, and modulation of proteins in the relevant signaling pathways. Aim 2: Determine the efficacy of AMR-MeOAc in the presence or absence of low dose FL118 using human pancreatic cancer cell line-derived xenograft models. Aim 3: Determine the efficacy of AMR-MeOAc in the presence or absence of low dose FL118 against xenografts directly derived from patient pancreatic cancer tissues. Pancreatic cancer with K-ras gain-of-function mutations and aberrant expression of one or more antiapoptotic proteins (survivin, Mcl-1, XIAP, cIAP2) is hard to treat. This project may develop a novel and targeted combination strategy to effectively control this challenging and difficult-to-treat cancer.