CiteULike: jyuh Firestein

The SIRT1 deacetylase suppresses intestinal tumorigenesis and colon cancer growth.

R Firestein — 2008-04-18T13:47:19-00:00

PLoS ONE, Vol. 3, No. 4. (2008)

Numerous longevity genes have been discovered in model organisms and altering their function results in prolonged lifespan. In mammals, some have speculated that any health benefits derived from manipulating these same pathways might be offset by increased cancer risk on account of their propensity to boost cell survival. The Sir2/SIRT1 family of NAD(+)-dependent deacetylases is proposed to underlie the health benefits of calorie restriction (CR), a diet that broadly suppresses cancer in mammals. Here we show that CR induces a two-fold increase SIRT1 expression in the intestine of rodents and that ectopic induction of SIRT1 in a beta-catenin-driven mouse model of colon cancer significantly reduces tumor formation, proliferation, and animal morbidity in the absence of CR. We show that SIRT1 deacetylates beta-catenin and suppresses its ability to activate transcription and drive cell proliferation. Moreover, SIRT1 promotes cytoplasmic localization of the otherwise nuclear-localized oncogenic form of beta-catenin. Consistent with this, a significant inverse correlation was found between the presence of nuclear SIRT1 and the oncogenic form of beta-catenin in 81 human colon tumor specimens analyzed. Taken together, these observations show that SIRT1 suppresses intestinal tumor formation in vivo and raise the prospect that therapies targeting SIRT1 may be of clinical use in beta-catenin-driven malignancies.

Altered uric acid levels and disease states.

MK Kutzing — 2008-05-08T03:57:51-00:00

The Journal of pharmacology and experimental therapeutics, Vol. 324, No. 1. (January 2008), pp. 1-7.

Altered serum uric acid concentrations, both above and below normal levels, have been linked to a number of disease states. An abnormally high uric acid level has been correlated with gout, hypertension, cardiovascular disease, and renal disease, whereas a reduced uric acid concentration has been linked to multiple sclerosis, Parkinson's disease, Alzheimer's disease, and optic neuritis. Historically, uric acid has been considered a marker of these disease states. Recent studies, however, have provided evidence that uric acid may actually play a role in the development or progression of such diseases. As a result, the manipulation of uric acid concentrations is now either included in, or being investigated for, the treatment of a variety of disease states.

Integrative genomic approaches identify IKBKE as a breast cancer oncogene.

JS Boehm — 2007-09-03T15:15:38-00:00

Cell, Vol. 129, No. 6. (15 June 2007), pp. 1065-1079.

Addgene: The karyotypic chaos exhibited by human epithelial cancers complicates efforts to identify mutations critical for malignant transformation. Here we integrate complementary genomic approaches to identify human oncogenes. We show that activation of the ERK and phosphatidylinositol 3-kinase (PI3K) signaling pathways cooperate to transform human cells. Using a library of activated kinases, we identify several kinases that replace PI3K signaling and render cells tumorigenic. Whole genome structural analyses reveal that one of these kinases, IKBKE (IKKepsilon), is amplified and overexpressed in breast cancer cell lines and patient-derived tumors. Suppression of IKKepsilon expression in breast cancer cell lines that harbor IKBKE amplifications induces cell death. IKKepsilon activates the nuclear factor-kappaB (NF-kappaB) pathway in both cell lines and breast cancers. These observations suggest a mechanism for NF-kappaB activation in breast cancer, implicate the NF-kappaB pathway as a downstream mediator of PI3K, and provide a framework for integrated genomic approaches in oncogene discovery.