tetrathiomolybdate and Colorectal-Neoplasms

Tetrathiomolybdate (TM) is an oral copper chelator under development as an anti-angiogenic agent. We evaluated TM in combination with irinotecan, 5-fluorouracil, and leucovorin (IFL). Serum vascular endothelial growth factor (VEGF), basic fibroblast growth factor, interleukin 6 (IL-6), and IL-8 were measured to evaluate the anti-angiogenic effect. Twenty-four patients with metastatic colorectal cancer were treated. The combination with IFL was well tolerated and dose intensity of IFL was maintained during combination therapy with TM. By intention to treat analysis, the overall response rate (RR) was 25% (95% CI 9.8-46.7) and the median time to progression (TTP) was 5.6 months (95% CI 2.7-7.7). VEGF levels were correlated with TTP, as were changes in VEGF, IL-8, and IL-6. TM can be safely added to IFL without compromising dose intensity or diminishing the expected RR. Changes in serum VEGF, IL-8, and IL-6 after treatment may directly reflect changes in CRC tissue angiogenesis.

Topics: Adenocarcinoma; Adult; Aged; Angiogenesis Inhibitors; Antineoplastic Combined Chemotherapy Protocols; Camptothecin; Chelating Agents; Colorectal Neoplasms; Copper; Cytokines; Disease-Free Survival; Female; Fluorouracil; Humans; Leucovorin; Male; Middle Aged; Molybdenum; Neoplasm Metastasis; Pilot Projects

Cancer is a major cause of death throughout the world, and there is a large need for better and more personalized approaches to combat the disease. Over the past decade, synthetic lethal approaches have been developed that are designed to exploit the aberrant molecular origins (i.e. defective genes) that underlie tumorigenesis. BLM and CHEK2 are two evolutionarily conserved genes that are somatically altered in a number of tumor types. Both proteins normally function in preserving genome stability through facilitating the accurate repair of DNA double strand breaks. Thus, uncovering synthetic lethal interactors of BLM and CHEK2 will identify novel candidate drug targets and lead chemical compounds. Here we identify an evolutionarily conserved synthetic lethal interaction between SOD1 and both BLM and CHEK2 in two distinct cell models. Using quantitative imaging microscopy, real-time cellular analyses, colony formation and tumor spheroid models we show that SOD1 silencing and inhibition (ATTM and LCS-1 treatments), or the induction of reactive oxygen species (2ME2 treatment) induces selective killing within BLM- and CHEK2-deficient cells relative to controls. We further show that increases in reactive oxygen species follow SOD1 silencing and inhibition that are associated with the persistence of DNA double strand breaks, and increases in apoptosis. Collectively, these data identify SOD1 as a novel candidate drug target in BLM and CHEK2 cancer contexts, and further suggest that 2ME2, ATTM and LCS-1 are lead therapeutic compounds warranting further pre-clinical study.

Topics: 2-Methoxyestradiol; Antineoplastic Agents; Apoptosis; Blotting, Western; Cell Line, Tumor; Checkpoint Kinase 2; Colorectal Neoplasms; DNA Breaks, Double-Stranded; Estradiol; Gene Knockdown Techniques; HCT116 Cells; Humans; Molybdenum; RecQ Helicases; RNA, Small Interfering; Superoxide Dismutase; Superoxide Dismutase-1; Transfection

Synthetic lethality is a rational approach to identify candidate drug targets for selective killing of cancer cells harboring somatic mutations that cause chromosome instability (CIN). To identify a set of the most highly connected synthetic lethal partner genes in yeast for subsequent testing in mammalian cells, we used the entire set of 692 yeast CIN genes to query the genome-wide synthetic lethal datasets. Hierarchical clustering revealed a highly connected set of synthetic lethal partners of yeast genes whose human orthologs are somatically mutated in colorectal cancer. Testing of a small matrix of synthetic lethal gene pairs in mammalian cells suggested that members of a pathway that remove reactive oxygen species that cause DNA damage would be excellent candidates for further testing. We show that the synthetic lethal interaction between budding yeast rad54 and sod1 is conserved within a human colorectal cancer context. Specifically, we demonstrate RAD54B-deficient cells are selectively killed relative to controls via siRNA-based silencing and chemical inhibition and further demonstrate that this interaction is conserved in an unrelated cell type. We further show that the DNA double strand breaks, resulting from increased reactive oxygen species following SOD1 inhibition, persist within the RAD54B-deficient cells and result in apoptosis. Collectively, these data identify SOD1 as a novel candidate cancer drug target and suggest that SOD1 inhibition may have broad-spectrum applicability in a variety of tumor types exhibiting RAD54B deficiencies.

Topics: 2-Methoxyestradiol; Apoptosis; Chromosomal Instability; Colorectal Neoplasms; DNA Breaks, Double-Stranded; DNA Helicases; Estradiol; Genes, Fungal; Genes, Lethal; HCT116 Cells; Humans; Molybdenum; Mutation; Nuclear Proteins; Reactive Oxygen Species; RNA, Small Interfering; Saccharomyces cerevisiae; Superoxide Dismutase; Superoxide Dismutase-1