Inhibition of Mitochondrial Translation As a Therapeutic Strategy for Acute Myeloid Leukemia (AML)

• Published in: Blood 2011-11, Vol.118 (21), p.233-233
• Main Authors: Skrtic, Marko, Sriskanthadevan, Shrivani, Livak, Bozhena, Gebbia, Marinella, Wang, Xiaoming, Wang, Zezhou, Hurren, Rose, Jitkova, Yulia, Gronda, Marcela, Maclean, Neil, Lai, Courteney, Eberhard, Yanina, Bartoszko, Justyna, Spagnuolo, Paul A., Rutledge, Angela, Datti, Alessandro, Ketela, Troy, Moffat, Jason, Robinson, Brian H, Cameron, Jessie M, Wrana, Jeff L., Eaves, Connie J., Minden, Mark D., Wang, Jean C.Y., Dick, John E., Humphries, R. Keith, Nislow, Corey, Giaever, Guri, Schimmer, Aaron D
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V118.21.233.233

Abstract 233 To identify novel therapeutic strategies that can eliminate AML and AML stem cells, we screened a library of on and off-patent drugs for candidates that could reduce the viability of engineered human AML cell lines that display the stem cell properties of differentiation, self-renewal, and marrow repopulation. This screen identified the anti-microbial agent tigecycline (TIG) as a top candidate with an LD50 of 3 to 8 uM, on 5 human AML cell lines. A lethal action was also demonstrated on 13 of 20 1°AML samples with similar potency (LD50 10 uM). We also found that 5 mM TIG reduced the clonogenic growth of 1°AML samples by 93±4% and was effective in reducing the ability of AML cells to regenerate disease in transplanted immunodeficient mice. In contrast, 5 uM TIG had no effect on the clonogenic growth or repopulating potential of normal human hematopoietic cells. To determine the mechanism of action of TIG, we used Haplo-Insufficiency Profiling, a functional chemical genomic screen, in S. cerevisiae. The Gene Ontology component that was the most enriched for TIG was the mitochondrial ribosome. We subsequently demonstrated that TIG inhibited mitochondrial but not cytoplasmic translation in AML cell lines and in 1°AML samples. Consistent with the inhibition of mitochondrial translation, TIG decreased the enzyme activity of Complex I and IV, which contain mitochondrially-translated subunits, but not complex II (nuclear-encoded subunits only). TIG also decreased oxygen consumption and decreased mitochondrial-membrane potential in AML cell lines and 1°AML samples, but not normal hematopoietic cells. Interestingly, unlike many mitochondrial inhibitors, TIG did not increase ROS production in AML cells. Additional experiments demonstrated that inhibition of mitochondrial translation was functionally important for the anti-leukemia activity of TIG. Next, we asked whether genetic strategies in leukemia cells would produce similar anti-leukemic effects as obtained with TIG. Knockdown of the mitochondrial-elongation factor EF-Tu mimicked the ability of TIG to inhibit mitochondrial translation, decrease mitochondrial membrane potential, decrease complex I and IV activity and induce cell death in AML cells. Also, EF-Tu knockdown did not increase ROS production. To investigate the basis of the hypersensitivity of AML cells to mitochondrial translation inhibit