Dyer, Roy B.

Abstract BACKGROUND Improved tests are needed for detection and management of prostate cancer. We hypothesized that differential gene expression in prostate tissue could help identify candidate blood biomarkers for prostate cancer and that blood from men with advanced prostate disease could be used to verify the biomarkers presence in circulation. METHODS We identified candidate markers using mRNA expression patterns from laser-capture microdissected prostate tissue and confirmed tissue expression using immunohistochemistry (IHC) for the subset of candidates having commercial antisera. We analyzed tissue extracts with tandem mass spectrometry (MS/MS) and measured blood concentrations using immunoassays and MS/MS of trypsin-digested, immunoextracted peptides. RESULTS We selected 35 novel candidate prostate adenocarcinoma biomarkers. For all 13 markers having commercial antisera for IHC, tissue expression was confirmed; 6 showed statistical discrimination between nondiseased and malignant tissue, and only 5 were detected in tissue extracts by MS/MS. Sixteen of the 35 candidate markers were successfully assayed in blood. Four of 8 biomarkers measured by ELISA and 3 of 10 measured by targeted MS showed statistically significant increases in blood concentrations of advanced prostate cancer cases, compared with controls. CONCLUSIONS Seven novel biomarkers identified by gene expression profiles in prostate tissue were shown to have statistically significant increased concentrations in blood from men with advanced prostate adenocarcinoma compared with controls: apolipoprotein C1, asporin, cartilage oligomeric matrix protein, chemokine (C-X-C motif) ligand 11 (CXCL11), CXCL9, coagulation factor V, and proprotein convertase subtilisin/kexin 6.

Allosteric regulation of heteromultimeric ATP-sensitive potassium (KATP) channels is unique among protein systems as it implies transmission of ligand-induced structural adaptation at the regulatory SUR subunit, a member of ATP-binding cassette ABCC family, to the distinct pore-forming K+ (Kir6.x) channel module. Cooperative interaction between nucleotide binding domains (NBDs) of SUR is a prerequisite for KATP channel gating, yet pathways of allosteric intersubunit communication remain uncertain. Here, we analyzed the role of the ED domain, a stretch of 15 negatively charged aspartate/glutamate amino acid residues (948–962) of the SUR2A isoform, in the regulation of cardiac KATP channels. Disruption of the ED domain impeded cooperative NBDs interaction and interrupted the regulation of KATP channel complexes by MgADP, potassium channel openers, and sulfonylurea drugs. Thus, the ED domain is a structural component of the allosteric pathway within the KATP channel complex integrating transduction of diverse nucleotide-dependent states in the regulatory SUR subunit to the open/closed states of the K+-conducting channel pore.

There has been a longstanding debate regarding the role of proteolysis in Huntington's disease. The toxic peptide theory posits that N-terminal cleavage fragments of mutant Huntington's disease protein [mutant huntingtin (mhtt)] enter the nucleus to cause transcriptional dysfunction. However, recent data suggest a second model in which proteolysis of full-length mhtt is inhibited. Importantly, the two competing theories differ with respect to subcellular distribution of mhtt at initiation of toxicity: nuclear if cleaved and cytoplasmic in the absence of cleavage. Using quantitative single-cell analysis and time-lapse imaging, we show here that transcriptional dysfunction is “downstream” of cytoplasmic dysfunction. Primary and reversible toxic events involve destabilization of microtubules mediated by full-length mhtt before cleavage. Restoration of microtubule structure by taxol inhibits nuclear entry and increases cell survival.