A SNP in the HTT promoter alters NF-κB binding and is a bidirectional genetic modifier of Huntington disease.

Cis-regulatory variants that alter gene expression can modify disease expressivity, but none have previously been identified in Huntington disease (HD). Here we provide in vivo evidence in HD patients that cis-regulatory variants in the HTT promoter are bidirectional modifiers of HD age of onset. HTT promoter analysis identified a NF-κB binding site that regulates HTT promoter transcriptional activity. A non-coding SNP, rs13102260:G > A, in this binding site impaired NF-κB binding and reduced HTT transcriptional activity and HTT protein expression. The presence of the rs13102260 minor (A) variant on the HD disease allele was associated with delayed age of onset in familial cases, whereas the presence of the rs13102260 (A) variant on the wild-type HTT allele was associated with earlier age of onset in HD patients in an extreme case-based cohort. Our findings suggest a previously unknown mechanism linking allele-specific effects of rs13102260 on HTT expression to HD age of onset and have implications for HTT silencing treatments that are currently in development.

BAG-1 expression correlates with Bcl-2, p53, differentiation, estrogen and progesterone receptors in invasive breast carcinoma.

BAG-1, a recently identified anti-apoptotic protein, is overexpressed in the majority of invasive breast carcinomas. Overexpression of BAG-1 is important for both multi-step oncogenesis and resistance of cancer cells to apoptosis induced by DNA-damaging alkylating agents. BAG-1 protein species are localized differentially; nuclear expression may be associated with a shorter disease-free and overall survival in early stage breast cancer, while cytoplasmic expression has been associated with longer survival in non-small cell lung cancer. Growing evidence suggests that Bcl-2 and p53 are also involved in the oncogenesis of breast cancer. Since BAG-1 interacts with Bcl-2 and is upregulated by mutant p53 in vitro, it would be interesting to determine if their expressions are correlated with each other and with other clinical prognostic factors in invasive breast cancer. To address this question we conducted a large scale retrospective study of BAG-1, Bcl-2 and p53 in 185 breast cancer patients. Our study again showed that BAG-1 is overexpressed in the majority of breast cancer patients. In addition, it demonstrated that the expression of BAG-1 correlates with that of Bcl-2, p53, differentiation, estrogen and progesterone receptors. Our clinical study supports the preclinical finding of the interaction between BAG-1 and Bcl-2, p53 and estrogen and progesterone receptors. Further experiments to explore the prognostic and therapeutic role of BAG-1 in breast cancer are warranted.

Antisense BAG-1 sensitizes HeLa cells to apoptosis by multiple pathways.

To study the mechanism of action of BAG-1 in drug-induced apoptosis, we constructed an antisense BAG-1 vector and established a stably transfected cell line from BAG-1-over-expressing HeLa cells. Reduced BAG-1 protein was confirmed by Western blot. Treatment of the antisense BAG-1-transfected cells with the anti-cancer drugs staurosporine, paclitaxel, all-trans retinoic acid (ATRA), and N-(4-hydroxyphenyl) retinamide (4-HPR) resulted in significantly enhanced apoptosis and reduced cell viability relative to vector-transfected cells. While the expression of p53 was increased, the level of Bcl-2 and Bax was decreased. Cells underexpressing BAG-1 had reduced cytosolic cytochrome c level. Treatment with staurosporine and paclitaxel resulted in increased cytochrome c release from mitochondria, whereas there was no change induced by treatment with ATRA and 4-HPR. Our experiments suggest that BAG-1 inhibits anti-cancer drug-induced apoptosis through apoptosis regulation pathways that may involve the mitochondrial Bcl-2/Bax ratio, p53, and differential anti-cancer drug-mediated cytochrome c release.