Abstract 5033: Targeted delivery of miR-122 into hepatocytes regresses liver metastasis

Abstract

Abstract Background: Metastatic tumors in the liver are 20 times more common than primary tumors and considered as a leading cause of mortality in several types of cancer. Therefore, making the liver (soil) inhospitable for tumor cells (seeds) to grow will have tremendous effects on outcome of multiple types of cancer. RNAi delivery -including miRNA delivery-shows promise for the development of novel molecular therapeutics that interfere with genes causing metastasis. Mir-122, which accounts for 70% of total miRNA population within the liver, is also known as a tumor suppressor miRNA within liver. We hypothesized that miR-122 delivery into hepatocytes can prevent development of metastatic colorectal cancer within mice liver. For testing this hypothesis, we used hepatic injection of ex-vivo engineered liver metastasis from human colorectal cancer cells to induce hepatic metastasis in nude mice and employed lipid calcium phosphate (LCP) nanoparticles for delivery of miR-122. Methods: LCP-miR122 and LCP-miRNC (negative control miRNA) were prepared mixing an emulsion of calcium which contained miRNA with a phosphate emulsion, followed by addition of DOPA to make the inner core of LCP. The outer leaflet of LCP contained DOTAP, Cholesterol and DSPE-PEG as. Galactose was conjugated at LCP surface for its targeted delivery to hepatocytes. For induction of hepatic metastasis, HT29-Luc cells were grown on liver biomatrix (BMX) for 7-10 days to acquire metastatic features and then harvested and injected into portal veins of nu/nu mice. Hepatic metastases formation was monitored weekly in vivo using bioluminescent imaging. LCP-miR122 or LCP-miRNC was systematically injected three times a week for 3 weeks starting 24 hours after tumor inoculations. Results: LCP particles were found to be 25-50 nm via dynamic light scattering analysis. When injected in vivo, LCP containing miR-122 was majorly distributed into liver (80%) and was detected in hepatocytes through confocal microscopy and target gene expression analysis. LCP-miR122 did not show any sign of hepatotoxicity or renal toxicity or any other pathological damage to other major organs. The injected conditioned HT29 cells formed metastatic foci within liver 1-3 weeks after portal vein injection as detected by bioluminescent imaging. Interestingly, we found that 67% of (6 out of 9) mice treated with LCP-miR122 did not show any sign of liver metastasis after 3 weeks compared with only 20% (2 out of 10) of mice treated with LCP containing negative control miRNA [OR=0.12, 95% CI:0.015-0.99; p=0.05]. Monitoring liver metastasis expansion on weekly basis, mice treated with LCP-miR122 showed a slight decrease in number of liver metastatic foci compared with control mice which showed a significant increase in number of liver metastatic foci during treatment [0.7 vs 3.8-fold; p=0.05]. Conclusion: These results suggest that targeted delivery of miR-122 into hepatocytes of patients prone to liver metastasis or harboring liver metastasis can prevent or regress hepatic metastasis. Citation Format: Hossein Sendi, Nikhila Sultanpuram, Jie Wang, Amanda Graboski, Liantao Li, Mengying Hu, Leaf Huang, Andrew Z. Wang. Targeted delivery of miR-122 into hepatocytes regresses liver metastasis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5033.