Selective linkage of mitochondrial enzymes to intracellular calcium stores differs between human-induced pluripotent stem cells, neural stem cells, and neurons.

Mitochondria and releasable endoplasmic reticulum (ER) calcium modulate neuronal calcium signaling, and both change in Alzheimer's disease (AD). The releasable calcium stores in the ER are exaggerated in fibroblasts from AD patients and in multiple models of AD. The activity of the alpha-ketoglutarate dehydrogenase complex (KGDHC), a key mitochondrial enzyme complex, is diminished in brains from AD patients, and can be plausibly linked to plaques and tangles. Our previous studies in cell lines and mouse neurons demonstrate that reductions in KGDHC increase the ER releasable calcium stores. The goal of these studies was to test whether the relationship was true in human iPSC-derived neurons. Inhibition of KGDHC for one or 24 hr increased the ER releasable calcium store in human neurons by 69% and 144%, respectively. The effect was mitochondrial enzyme specific because inhibiting the pyruvate dehydrogenase complex, another key mitochondrial enzyme complex, diminished the ER releasable calcium stores. The link of KGDHC to ER releasable calcium stores was cell type specific as the interaction was not present in iPSC or neural stem cells. Thus, these studies in human neurons verify a link between KGDHC and releasable ER calcium stores, and support the use of human neurons to examine mechanisms and potential therapies for AD.

Mitochondria/metabolic reprogramming in the formation of neurons from peripheral cells: Cause or consequence and the implications to their utility.

The induction of pluripotent stem cells (iPSC) from differentiated cells such as fibroblasts and their subsequent conversion to neural progenitor cells (NPC) and finally to neurons is intriguing scientifically, and its potential to medicine is nearly infinite, but unrealized. A better understanding of the changes at each step of the transformation will enable investigators to better model neurological disease. Each step of conversion from a differentiated cell to an iPSC to a NPC to neurons requires large changes in glycolysis including aerobic glycolysis, the pentose shunt, the tricarboxylic acid cycle, the electron transport chain and in the production of reactive oxygen species (ROS). These mitochondrial/metabolic changes are required and their manipulation modifies conversions. These same mitochondrial/metabolic processes are altered in common neurological diseases so that factors related to the disease may alter the cellular transformation at each step including the final phenotype. A lack of understanding of these interactions could compromise the validity of the disease comparisons in iPSC derived neurons. Both the complexity and potential of iPSC derived cells for understanding and treating disease remain great.

Interactions of Mitochondria/Metabolism and Calcium Regulation in Alzheimer's Disease: A Calcinist Point of View.

Decades of research suggest that alterations in calcium are central to the pathophysiology of Alzheimer's Disease (AD). Highly reproducible changes in calcium dynamics occur in cells from patients with both genetic and non-genetic forms of AD relative to controls. The most robust change is an exaggerated release of calcium from internal stores. Detailed analysis of these changes in animal and cell models of the AD-causing presenilin mutations reveal robust changes in ryanodine receptors, inositol tris-phosphate receptors, calcium leak channels and store activated calcium entry. Similar anomalies in calcium result when AD-like changes in mitochondrial enzymes or oxidative stress are induced experimentally. The calcium abnormalities can be directly linked to the altered tau phosphorylation, amyloid precursor protein processing and synaptic dysfunction that are defining features of AD. A better understanding of these changes is required before using calcium abnormalities as therapeutic targets.

Heat shock factor 1 induces cancer stem cell phenotype in breast cancer cell lines.

Heat shock factor 1 (HSF1) has long been recognized as the master transcription factor that regulates heat shock proteins (HSPs).  More recently HSF1 has been associated with a broader role in regulating response to a variety of cellular stresses beyond heat-shock.  We previously found that high HSF1 expression is associated with poor outcome in lung, breast and colon cancers. Importantly, however, the HSF1 signature correlated with poor outcome in these studies was not related to the heat shock response, which suggested that tumor outcome associated with high HSF expression may be due to processes other than stress response. Hence, we explored the question whether high HSF1 expression might be associated with the cancer stem cell (CSC) phenotype. To do so, we examined the association of HSF1 with CSC phenotype by FACS and immunofluorescence. In addition, we evaluated the effects of HSF1 over-expression and knock-down on sphere formation and CSC marker expression in breast cancer cell lines. Here, we report results demonstrating that high HSF1 not only correlates with CSC marker expression, but inducible HSF1 over-expression augments and HSF1 knock-down inhibits CSC phenotype. Furthermore, HSF1 expression confers resistance to chemotherapeutic drugs and increases CSC frequency. In conclusion, our study indicates that one of the potential HSP-independent HSF1 driven mechanisms that may contribute to poor outcome in human tumors involves regulation of the CSC phenotype. Hence, therapeutic inhibition of HSF1 may be one route to target CSCs in human tumors.

Cost-effectiveness analysis of nebivolol and metoprolol in essential hypertension: a pharmacoeconomic comparison of antihypertensive efficacy of beta blockers.

OBJECTIVE: To estimate and compare the cost-effectiveness and safety of nebivolol with sustained-release metoprolol in reducing blood pressure by 1 mm of Hg per day in hypertensive patients. MATERIALS AND METHODS: This was a prospective, randomized, open label, observational analysis of cost-effectiveness, in a questionnaire-based fashion to compare the cost of nebivolol (2.5 mg, 5 mg, 10 mg) and sustained released metoprolol succinate (25 mg, 50 mg, 100 mg) in hypertensive patients using either of the two drugs. A total of 60 newly detected drug naïve hypertensive patients were considered for the comparison, of which 30 patients were prescribed nebivolol and the other 30 were prescribed metoprolol succinate as per the recommended dosage. Based on the data, statistical analysis was carried out using GraphPad Prism 5 and MS Excel Spreadsheet 2007. RESULT: The cost of reducing 1 mm of Hg blood pressure per day with nebivolol was 0.60, 0.70, and 1.06 INR, whereas that of metoprolol succinate was 0.93, 1.18, and 1.25 INR at their respective equivalent doses, hence significantly lower with the nebivolol group as compared to the metoprolol group (P < 0.05). CONCLUSION: This pharmacoeconomic analysis shows that nebivolol is more cost-effective as compared to metoprolol when the cost per reduction in blood pressure per day is considered. This may affect the patients economically during their long-term use of these molecules for the treatment of hypertension.

Taxonomy of breast cancer based on normal cell phenotype predicts outcome.

Accurate classification is essential for understanding the pathophysiology of a disease and can inform therapeutic choices. For hematopoietic malignancies, a classification scheme based on the phenotypic similarity between tumor cells and normal cells has been successfully used to define tumor subtypes; however, use of normal cell types as a reference by which to classify solid tumors has not been widely emulated, in part due to more limited understanding of epithelial cell differentiation compared with hematopoiesis. To provide a better definition of the subtypes of epithelial cells comprising the breast epithelium, we performed a systematic analysis of a large set of breast epithelial markers in more than 15,000 normal breast cells, which identified 11 differentiation states for normal luminal cells. We then applied information from this analysis to classify human breast tumors based on normal cell types into 4 major subtypes, HR0-HR3, which were differentiated by vitamin D, androgen, and estrogen hormone receptor (HR) expression. Examination of 3,157 human breast tumors revealed that these HR subtypes were distinct from the current classification scheme, which is based on estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Patient outcomes were best when tumors expressed all 3 hormone receptors (subtype HR3) and worst when they expressed none of the receptors (subtype HR0). Together, these data provide an ontological classification scheme associated with patient survival differences and provides actionable insights for treating breast tumors.