New microRNA biotechnology as an in vivo therapeutic molecule to inhibit cancer

Brad A. Amendt; Steven Eliason; Adil Akkouch; Huojun Cao; Liu Hong

doi:10.1096/fasebj.2018.32.1_supplement.807.13

MicroRNAs (miRs) are biomarkers of cancer development and progression, they regulate cell fate, stemness and embryonic development. It is well‐known that miRs play a role in cancer and are associated with numerous types of cancer as either oncogenes or tumor‐suppressor genes. We developed the Plasmid‐based microRNA Inhibitor System (PMIS), and it is the only miR inhibitor that can be used to generate transgenic mice to study the role of miRs during embryonic development and as disease models. The PMIS is very stable, efficient, has high specificity and affinity for specific miRs and is not toxic to cells or animals. We focused on miR‐210 as it is increased in human colon cancer. The PMIS‐miR‐210 lentivirus construct and plasmid both express GFP. We made PMIS‐miR‐210 and PMIS‐vector only stably transduced human SW620 colon cancer cell lines to determine the effect of inhibiting miR‐210 on cell growth and phenotypes. The cells were transduced with the lentivirus and GFP expressing cells were FACS sorted and analyzed for growth. The PMIS‐miR‐210 cells proliferated very slowly (25% of the rate of PMIS‐vector only cells). RNA‐sequencing experiments and bioinformatics analyses revealed several new genes targeted by miR‐210 and new pathways in colon tumor progression. We have identified a miR regulatory loop controlling the expression of other miRs. Nude mice were injected with PMIS‐miR‐210 or PMIS‐vector stably expressing human colon cancer cells and 5 out of 8 mice with colon cancer cells expressing PMIS‐miR‐210 did not form tumors compared to the controls (PMIS‐vector, 8 of 8 had tumors). To demonstrate the effectiveness of PMIS‐miR‐210 as a therapeutic, nude mice were injected with colon cancer cells and tumors were allowed to form (3 weeks), mice were then injected with naked plasmid DNA PMIS‐miR‐210 or vector control into and surrounding the solid tumor mass at several concentrations. No tumors were observed in 6 of the 10 mice injected with PMIS‐miR‐210 and the other 4 mice had small tumors compared to controls after 2 weeks of further growth (PMIS‐vector, 10 of 10 had no effect on tumor growth). This is the first time that direct injection of a naked plasmid DNA expressing the PMIS microRNA inhibitor reduced or completely inhibited tumor growth, without using toxic delivery systems. The PMIS has great potential as a new therapeutic biological drug for cancer treatments. Support or Funding Information This work was supported by National Institutes of Health grant DE026433. PMIS‐miR‐210 inhibits colon cancer tumor growth A) Transduced colon cancer cells with either PMIS empty vector or PMIS‐miR‐210 were injected into nude mice and after 4 weeks the tumors were analyzed. B,C) Untreated colon cancer cells were put into nude mice and after 3 weeks, tumors were injected with PMIS empty vector or PMIS‐miR‐210, 2 weeks later the tumors were harvested and analyzed. This is from the Experimental Biology 2018 Meeting. There is no full text article associated with this published in The FASEB Journal.

New microRNA biotechnology as an in vivo therapeutic molecule to inhibit cancer

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