Protein expression analysis of chronic lymphocytic leukemia defines the effect of genetic aberrations and uncovers a correlation of CDK4, P27 and P53 with hierarchical risk.

BACKGROUND: Chronic lymphocytic leukemia has a variable clinical course. Genomic aberrations identify prognostic subgroups, pointing towards distinct underlying biological mechanisms that are poorly understood. In particular it remains unclear whether the prognostic subgroups of chronic lymphocytic leukemia are characterized by different levels of leukemogenic proteins. DESIGN AND METHODS: Expression of 23 proteins involved in apoptosis, proliferation, DNA damage, and signaling or whose genes map to chromosomal regions known to be critical in chronic lymphocytic leukemia was quantified in 185 cytogenetically well characterized cases of chronic lymphocytic leukemia using immunoblotting. Cases were categorized hierarchically into deletion(17p), deletion(11q), trisomy 12, deletion(13q) as sole abnormality or normal karyotype. Statistical analysis was performed for expression differences between these subgroups. In addition, the expression levels of CDK4, P27 and P53 were quantified over the clinical course and compared to levels in immunopurified B cells from healthy individuals. RESULTS: In subgroups with a good prognosis, differential expression was mainly seen for proteins that regulate apoptosis. In contrast, in cytogenetic subgroups with a worse prognosis, differential expression was mostly detected for proteins that control DNA damage and proliferation. Expression levels of CDK4, P27 and P53 were higher compared to those in B cells from healthy individuals and significantly correlated with increasing hierarchical risk. In addition, no significant longitudinal changes of expression levels of CDK4, P27 and P53 could be detected in chronic lymphocytic leukemia patients. CONCLUSIONS: Differences in expression levels of apoptosis- and proliferation-controlling proteins define distinct prognostic subgroups of chronic lymphocytic leukemia and uncover a correlation of levels of CDK4, P27 and P53 proteins with higher hierarchical risk.

Structures of storage-induced transformation products of the beer's bitter principles, revealed by sophisticated NMR spectroscopic and LC-MS techniques.

Besides undesirable changes in the attractive aroma, a significant decrease in the intensity of the bitterness as well as a change of the taste into a lingering, harsh bitterness has long been known as a shelf-life limiting factor of beer. Multiple studies have demonstrated that the aging of beer induces a decrease of the total amount of cis- and trans-iso-alpha-acids, the well-known bitter principles of beer. Although the trans-iso-alpha-acids exclusively, not the cis-iso-alpha-acids, were found to be degraded upon storage of beer, the key transformation products formed exclusively from the trans isomers in beer are not known. In the present study, suitable model experiments followed by LC-MS/MS and sophisticated NMR spectroscopic experiments, including the measurement of residual dipolar couplings (RDCs) in gel-based alignment media as well as a novel broadband and B(1)-field-compensated incredible natural abundance double-quantum transfer experiment (INADEQUATE) pulse sequence, enabled the identification of a series of previously unknown trans-specific iso-alpha-acid transformation products, namely, tricyclocohumol, tricyclocohumene, isotricyclocohumene, tetracyclocohumol, and epitetracyclocohumol, respectively. HPLC-MS/MS analysis of these compounds, which exhibit the aforementioned harsh lingering bitter taste and have threshold concentrations ranging from 5 to 70 micromol L(-1), confirmed their generation during aging of beer and, for the first time, explained the storage-induced changes of the beer's bitter taste on a molecular level.