Pleiotropic Anticancer Properties of Scorpion Venom Peptides: Rhopalurus princeps Venom as an Anticancer Agent.

To date, the success of conventional chemotherapy, radiotherapy, and targeted biological therapies in cancer treatment is not satisfactory. The main reasons for such outcomes rely on low target selectivity, primarily in chemo- and radiotherapy, ineffectiveness to metastatic disease, drug resistance, and severe side effects. Although immune checkpoint inhibitors may offer better clinical promise, success is still limited. Since cancer is a complex systemic disease, the need for new therapeutic modalities that can target or block several steps of cancer cell characteristics, modulate or repolarize immune cells, and are less toxic to healthy tissues is essential. Of these promising therapeutic modalities are pleiotropic natural products in which scorpion venom (SV) is an excellent example. SV consists of complex bioactive peptides that are disulfide-rich of different peptides' length, potent, stable, and exerts various multi-pharmacological actions. SV peptides also contain ion channel inhibitors. These ion channels are dysregulated and overexpressed in cancer cells, and play essential roles in cancer development and invasion, as well as depolarizing immune cells. Furthermore, SV has been found to induce cancer cell apoptosis, and inhibit cancer cells proliferation, invasion, metastasis, and angiogenesis. In the current review, we are presenting data that show the pleiotropic effect of SV against different types of human cancer as well as revealing one potential anticancer agent, Rhopalurus princeps venom. Furthermore, we are addressing what is needed to be done to translate these potential cancer therapeutics to the clinic.

3-Bromopyruvate as a potent anticancer therapy in honor and memory of the late Professor André Goffeau.

3-Bromopyruvate (3BP) is a small, highly reactive molecule formed by bromination of pyruvate. In the year 2000, the antitumor properties of 3BP were discovered. Studies using animal models proved its high efficacy for anticancer therapy with no apparent side effects. This was also found to be the case in a limited number of cancer patients treated with 3BP. Due to the "Warburg effect," most tumor cells exhibit metabolic changes, for example, increased glucose consumption and lactic acid production resulting from mitochondrial-bound overexpressed hexokinase 2. Such alterations promote cell migration, immortality via inhibition of apoptosis, and less dependence on the availability of oxygen. Significantly, these attributes also make cancer cells more sensitive to agents, such as 3BP that inhibits energy production pathways without harming normal cells. This selectivity of 3BP is mainly due to overexpressed monocarboxylate transporters in cancer cells. Furthermore, 3BP is not a substrate for any pumps belonging to the ATP-binding cassette superfamily, which confers resistance to a variety of drugs. Also, 3BP has the capacity to induce multiple forms of cell death, by, for example, ATP depletion resulting from inactivation of both glycolytic and mitochondrial energy production pathways. In addition to its anticancer property, 3BP also exhibits antimicrobial activity. Various species of microorganisms are characterized by different susceptibility to 3BP inhibition. Among tested strains, the most sensitive was found to be the pathogenic yeast-like fungus Cryptococcus neoformans. Significantly, studies carried out in our laboratories have shown that 3BP exhibits a remarkable capacity to eradicate cancer cells, fungi, and algae.

The HK2 Dependent "Warburg Effect" and Mitochondrial Oxidative Phosphorylation in Cancer: Targets for Effective Therapy with 3-Bromopyruvate.

This review summarizes the current state of knowledge about the metabolism of cancer cells, especially with respect to the "Warburg" and "Crabtree" effects. This work also summarizes two key discoveries, one of which relates to hexokinase-2 (HK2), a major player in both the "Warburg effect" and cancer cell immortalization. The second discovery relates to the finding that cancer cells, unlike normal cells, derive as much as 60% of their ATP from glycolysis via the "Warburg effect", and the remaining 40% is derived from mitochondrial oxidative phosphorylation. Also described are selected anticancer agents which generally act as strong energy blockers inside cancer cells. Among them, much attention has focused on 3-bromopyruvate (3BP). This small alkylating compound targets both the "Warburg effect", i.e., elevated glycolysis even in the presence oxygen, as well as mitochondrial oxidative phosphorylation in cancer cells. Normal cells remain unharmed. 3BP rapidly kills cancer cells growing in tissue culture, eradicates tumors in animals, and prevents metastasis. In addition, properly formulated 3BP shows promise also as an effective anti-liver cancer agent in humans and is effective also toward cancers known as "multiple myeloma". Finally, 3BP has been shown to significantly extend the life of a human patient for which no other options were available. Thus, it can be stated that 3BP is a very promising new anti-cancer agent in the process of undergoing clinical development.

Glutathione may have implications in the design of 3-bromopyruvate treatment protocols for both fungal and algal infections as well as multiple myeloma.

In different fungal and algal species, the intracellular concentration of reduced glutathione (GSH) correlates closely with their susceptibility to killing by the small molecule alkylating agent 3-bromopyruvate (3BP). Additionally, in the case of Cryptococcus neoformans cells 3BP exhibits a synergistic effect with buthionine sulfoximine (BSO), a known GSH depletion agent. This effect was observed when 3BP and BSO were used together at concentrations respectively of 4-5 and almost 8 times lower than their Minimal Inhibitory Concentration (MIC). Finally, at different concentrations of 3BP (equal to the half-MIC, MIC and double-MIC in a case of fungi, 1 mM and 2.5 mM for microalgae and 25, 50, 100 µM for human multiple myeloma (MM) cells), a significant decrease in GSH concentration is observed inside microorganisms as well as tumor cells. In contrast to the GSH concentration decrease, the presence of 3BP at concentrations corresponding to sub-MIC values or half maximal inhibitory concentration (IC50) clearly results in increasing the expression of genes encoding enzymes involved in the synthesis of GSH in Cryptococcus neoformans and MM cells. Moreover, as shown for the first time in the MM cell model, the drastic decrease in the ATP level and GSH concentration and the increase in the amount of ROS caused by 3BP ultimately results in cell death.

Screening the yeast genome for energetic metabolism pathways involved in a phenotypic response to the anti-cancer agent 3-bromopyruvate.

In this study the detailed characteristic of the anti-cancer agent 3-bromopyruvate (3-BP) activity in the yeast Saccharomyces cerevisiae model is described, with the emphasis on its influence on energetic metabolism of the cell. It shows that 3-BP toxicity in yeast is strain-dependent and influenced by the glucose-repression system. Its toxic effect is mainly due to the rapid depletion of intracellular ATP. Moreover, lack of the Whi2p phosphatase results in strongly increased sensitivity of yeast cells to 3-BP, possibly due to the non-functional system of mitophagy of damaged mitochondria through the Ras-cAMP-PKA pathway. Single deletions of genes encoding glycolytic enzymes, the TCA cycle enzymes and mitochondrial carriers result in multiple effects after 3-BP treatment. However, it can be concluded that activity of the pentose phosphate pathway is necessary to prevent the toxicity of 3-BP, probably due to the fact that large amounts of NADPH are produced by this pathway, ensuring the reducing force needed for glutathione reduction, crucial to cope with the oxidative stress. Moreover, single deletions of genes encoding the TCA cycle enzymes and mitochondrial carriers generally cause sensitivity to 3-BP, while totally inactive mitochondrial respiration in the rho0 mutant resulted in increased resistance to 3-BP.

Dysregulated metabolism contributes to oncogenesis.

Cancer is a disease characterized by unrestrained cellular proliferation. In order to sustain growth, cancer cells undergo a complex metabolic rearrangement characterized by changes in metabolic pathways involved in energy production and biosynthetic processes. The relevance of the metabolic transformation of cancer cells has been recently included in the updated version of the review "Hallmarks of Cancer", where dysregulation of cellular metabolism was included as an emerging hallmark. While several lines of evidence suggest that metabolic rewiring is orchestrated by the concerted action of oncogenes and tumor suppressor genes, in some circumstances altered metabolism can play a primary role in oncogenesis. Recently, mutations of cytosolic and mitochondrial enzymes involved in key metabolic pathways have been associated with hereditary and sporadic forms of cancer. Together, these results demonstrate that aberrant metabolism, once seen just as an epiphenomenon of oncogenic reprogramming, plays a key role in oncogenesis with the power to control both genetic and epigenetic events in cells. In this review, we discuss the relationship between metabolism and cancer, as part of a larger effort to identify a broad-spectrum of therapeutic approaches. We focus on major alterations in nutrient metabolism and the emerging link between metabolism and epigenetics. Finally, we discuss potential strategies to manipulate metabolism in cancer and tradeoffs that should be considered. More research on the suite of metabolic alterations in cancer holds the potential to discover novel approaches to treat it.

The cytotoxicity of 3-bromopyruvate in breast cancer cells depends on extracellular pH.

Although the anti-cancer properties of 3BP (3-bromopyruvate) have been described previously, its selectivity for cancer cells still needs to be explained [Ko et al. (2001) Cancer Lett. 173, 83-91]. In the present study, we characterized the kinetic parameters of radiolabelled [14C] 3BP uptake in three breast cancer cell lines that display different levels of resistance to 3BP: ZR-75-1 < MCF-7 < SK-BR-3. At pH 6.0, the affinity of cancer cells for 3BP transport correlates with their sensitivity, a pattern that does not occur at pH 7.4. In the three cell lines, the uptake of 3BP is dependent on the protonmotive force and is decreased by MCTs (monocarboxylate transporters) inhibitors. In the SK-BR-3 cell line, a sodium-dependent transport also occurs. Butyrate promotes the localization of MCT-1 at the plasma membrane and increases the level of MCT-4 expression, leading to a higher sensitivity for 3BP. In the present study, we demonstrate that this phenotype is accompanied by an increase in affinity for 3BP uptake. Our results confirm the role of MCTs, especially MCT-1, in 3BP uptake and the importance of cluster of differentiation (CD) 147 glycosylation in this process. We find that the affinity for 3BP transport is higher when the extracellular milieu is acidic. This is a typical phenotype of tumour microenvironment and explains the lack of secondary effects of 3BP already described in in vivo studies [Ko et al. (2004) Biochem. Biophys. Res. Commun. 324, 269-275].

Killing multiple myeloma cells with the small molecule 3-bromopyruvate: implications for therapy.

The small molecule 3-bromopyruvate (3-BP), which has emerged recently as the first member of a new class of potent anticancer agents, was tested for its capacity to kill multiple myeloma (MM) cancer cells. Human MM cells (RPMI 8226) begin to lose viability significantly within 8 h of incubation in the presence of 3-BP. The Km (0.3 mmol/l) for intracellular accumulation of 3-BP in MM cells is 24 times lower than that in control cells (7.2 mmol/l). Therefore, the uptake of 3-BP by MM cells is significantly higher than that by peripheral blood mononuclear cells. Further, the IC50 values for human MM cells and control peripheral blood mononuclear cells are 24 and 58 µmol/l, respectively. Therefore, specificity and selectivity of 3-BP toward MM cancer cells are evident on the basis of the above. In MM cells the transcription levels of the gene encoding the monocarboxylate transporter MCT1 is significantly amplified compared with control cells. The level of intracellular ATP in MM cells decreases by over 90% within 1 h after addition of 100 µmol/l 3-BP. The cytotoxicity of 3-BP, exemplified by a marked decrease in viability of MM cells, is potentiated by the inhibitor of glutathione synthesis buthionine sulfoximine. In addition, the lack of mutagenicity and its superior capacity relative to Glivec to kill MM cancer cells are presented in this study.

3-Bromopyruvate: a novel antifungal agent against the human pathogen Cryptococcus neoformans.

We have investigated the antifungal activity of the pyruvic acid analogue: 3-bromopyruvate (3-BP). Growth inhibition by 3-BP of 110 strains of yeast-like and filamentous fungi was tested by standard spot tests or microdilution method. The human pathogen Cryptococcus neoformans exhibited a low Minimal Inhibitory Concentration (MIC) of 0.12-0.15 mM 3-BP. The high toxicity of 3-BP toward C. neoformans correlated with high intracellular accumulation of 3-BP and also with low levels of intracellular ATP and glutathione. Weak cytotoxicity towards mammalian cells and lack of resistance conferred by the PDR (Pleiotropic Drug Resistance) network in the yeast Saccharomyces cerevisiae, are other properties of 3-BP that makes it a novel promising anticryptococcal drug.

Mitochondria in relation to cancer metastasis: introduction to a mini-review series.

This introductory article and those that follow focus on the roles that mitochondria may have in cancer metastasis (spreading) that all too frequently leads to death of cancer patients. The history of cancer dates back in time to several thousand years BC and continues to this day. Although billions of dollars have been invested, numerous cancer researchers/scientists and oncologist located at universities, hospitals, cancer centers, commercial entities (companies), and government agencies have been unable to discover "magic bullets" to quickly silence most cancers. That is, agents that are effective not only in eradicating the primary tumor at its site of origin, but eradicating also distant tumors that have arisen therefrom via metastatic cells. Fortunately, in recent years some researchers have obtained evidence that the mitochondria of cancer cells are involved not only in providing in part the necessary energy (ATP) to fuel their growth, but hold the secrets to their immortality, and propensity to metastasize (spread) from their original site of origin to other body locations. This introductory article, as well as those that follow, focus on the possible roles of mitochondria in cancer metastasis as well as strategies to arrest cancer metastasis based on this knowledge. Ideally, for a patient to become "cancer free" the anticancer agent/agents used must 1) eradicate the primary tumor at its site of origin, 2) eradicate any tumors at other body locations that have arisen via metastasis, and 3) eradicate any tumor cells that remain in the blood, i.e., circulating tumor cells. One such agent that holds promise for doing all three is the small molecule 3-bromopyruvate (3BP) discovered in the author's laboratory by Dr. Young H. Ko near the turn of the century to be a potent anti-cancer agent [Ko et al.(2001) Can Lett 173:83-91].

3-Bromopyruvate (3BP) a fast acting, promising, powerful, specific, and effective "small molecule" anti-cancer agent taken from labside to bedside: introduction to a special issue.

Although the "Warburg effect", i.e., elevated glucose metabolism to lactic acid (glycolysis) even in the presence of oxygen, has been recognized as the most common biochemical phenotype of cancer for over 80 years, its biochemical and genetic basis remained unknown for over 50 years. Work focused on elucidating the underlying mechanism(s) of the "Warburg effect" commenced in the author's laboratory in 1969. By 1985 among the novel findings made two related most directly to the basis of the "Warburg effect", the first that the mitochondrial content of tumors exhibiting this phenotype is markedly decreased relative to the tissue of origin, and the second that such mitochondria have markedly elevated amounts of the enzyme hexokinase-2 (HK2) bound to their outer membrane. HK2 is the first of a number of enzymes in cancer cells involved in metabolizing the sugar glucose to lactic acid. At its mitochondrial location HK2 binds at/near the protein VDAC (voltage dependent anion channel), escapes inhibition by its product glucose-6-phosphate, and gains access to mitochondrial produced ATP. As shown by others, it also helps immortalize cancer cells, i.e., prevents cell death. Based on these studies, the author's laboratory commenced experiments to elucidate the gene basis for the overexpression of HK2 in cancer. These studies led to both the discovery of a unique HK2 promoter region markedly activated by both hypoxic conditions and moderately activated by several metabolites (e.g., glucose), Also discovered was the promoter's regulation by epigenetic events (i.e., methylation, demethylation). Finally, the author's laboratory turned to the most important objective. Could they selectively and completely destroy cancerous tumors in animals? This led to the discovery in an experiment conceived, designed, and conducted by Young Ko that the small molecule 3-bromopyruvate (3BP), the subject of this mini-review series, is an incredibly powerful and swift acting anticancer agent. Significantly, in subsequent experiments with rodents (19 animals with advanced cancer) Ko led a project in which 3BP was shown in a short treatment period to eradicate all (100%). Ko's and co-author's findings once published attracted global attention leading world-wide to many other studies and publications related to 3BP and its potent anti-cancer effect. This Issue of the Journal of Bioenergetics and Biomembranes (JOBB 44-1) captures only a sampling of research conducted to date on 3BP as an anticancer agent, and includes also a Case Report on the first human patient known to the author to be treated with specially formulated 3BP. Suffice it to say in this bottom line, "3BP, a small molecule, results in a remarkable therapeutic effect when it comes to treating cancers exhibiting a "Warburg effect". This includes most cancer types.

Transport and cytotoxicity of the anticancer drug 3-bromopyruvate in the yeast Saccharomyces cerevisiae.

We have investigated the cytotoxicity in Saccharomyces cerevisiae of the novel antitumor agent 3-bromopyruvate (3-BP). 3-BP enters the yeast cells through the lactate/pyruvate H(+) symporter Jen1p and inhibits cell growth at minimal inhibitory concentration of 1.8 mM when grown on non-glucose conditions. It is not submitted to the efflux pumps conferring Pleiotropic Drug Resistance in yeast. Yeast growth is more sensitive to 3-BP than Gleevec (Imatinib methanesulfonate) which in contrast to 3-BP is submitted to the PDR network of efflux pumps. The sensitivity of yeast to 3-BP is increased considerably by mutations or chemical treatment by buthionine sulfoximine that decrease the intracellular concentration of glutathione.

Butyrate activates the monocarboxylate transporter MCT4 expression in breast cancer cells and enhances the antitumor activity of 3-bromopyruvate.

Most malignant tumors exhibit the Warburg effect, which consists in increased glycolysis rates with production of lactate, even in the presence of oxygen. Monocarboxylate transporters (MCTs), maintain these glycolytic rates, by mediating the influx and/or efflux of lactate and are overexpressed in several cancer cell types. The lactate and pyruvate analogue 3-bromopyruvate (3-BP) is an inhibitor of the energy metabolism, which has been proposed as a specific antitumor agent. In the present study, we aimed at determining the effect of 3-BP in breast cancer cells and evaluated the putative role of MCTs on this effect. Our results showed that the three breast cancer cell lines used presented different sensitivities to 3-BP: ZR-75-1 ER (+)>MCF-7 ER (+)>SK-BR-3 ER (-). We also demonstrated that 3-BP reduced lactate production, induced cell morphological alterations and increased apoptosis. The effect of 3-BP appears to be cytotoxic rather than cytostatic, as a continued decrease in cell viability was observed after removal of 3-BP. We showed that pre-incubation with butyrate enhanced significantly 3-BP cytotoxicity, especially in the most resistant breast cancer cell line, SK-BR-3. We observed that butyrate treatment induced localization of MCT1 in the plasma membrane as well as overexpression of MCT4 and its chaperone CD147. Our results thus indicate that butyrate pre-treatment potentiates the effect of 3-BP, most probably by increasing the rates of 3-BP transport through MCT1/4. This study supports the potential use of butyrate as adjuvant of 3-BP in the treatment of breast cancer resistant cells, namely ER (-).

Mitochondrial ATP synthase catalytic mechanism: a novel visual comparative structural approach emphasizes pivotal roles for Mg²âº and P-loop residues in making ATP.

The mitochondrial ATP synthase (F(o)F(1)) is one of the most abundant, important, and complex enzymes found in animals and humans. In earlier studies, we used the photosensitive phosphate analogue vanadate (V(i)) to study the enzyme's mechanism in the transition state. Significantly, these studies showed that Mg(2+) plays an important role in transition state formation during ATP synthesis. Additionally, in both MgADP·V(i)-F(1) and MgV(i)-F(1) complexes, photoactivation of orthovanadate (V(i)) induced cleavage at the third residue within the P-loop (GGAGVGKT), i.e., ßA158, suggesting its proximity to the γ-phosphate during transition state formation. However, despite our recent release of the F(1)-ATPase structure containing V(i), the structural details regarding the role of Mg(2+) have remained elusive. Therefore, in this study, we sought to improve our understanding of the essential role of Mg(2+) during transition state formation. We utilized Protein Data Bank structural data representing different conformational intermediates of key steps in ATP synthesis to assemble a database of positional relationships between landmark residues of the catalytic site and the bound ligand. Applying novel bioinformatics methods, we combined the resulting interatomic spatial data with an animated model of the catalytic site to visualize the exact nature of the changes in these positional relationships during ATP synthesis. The results of these studies reported here show that the absence of Mg(2+) results in migration of inorganic phosphate (P(i)) from ßA158 to a more medial position in the P-loop binding pocket, thereby disrupting essential placement and orientation of the P(i) needed to form the transition state structure and therefore MgATP.

Human Hepatocellular Carcinoma Metabolism: Imaging by Hyperpolarized 13C Magnetic Resonance Spectroscopy.

PURPOSE: Most cancers exhibit high levels of aerobic glycolytic metabolism with diminished levels of mitochondrial oxidative phosphorylation even in the presence of normal or near-normal levels of oxygen ("Warburg effect"). However, technical challenges have limited the development of non-invasive in vivo imaging techniques for monitoring glycolytic metabolism of hepatocellular carcinoma (HCC) and quantitatively evaluating the impact of this effect on the growth and therapy of this disease. Thus, there is a critical need to develop non-invasive techniques for longitudinal assessment of the metabolism and treatment response of patients with unresectable HCCs. PROCEDURES: This article discusses a novel method, "Hyperpolarized 13C MRS imaging", for achieving this objective and thus improving the prognosis of HCC patients. The primary objective has been to characterize in vivo metabolic biomarkers as determinants of HCC metabolism and treatment response of unresectable HCC tumors or viable HCC cells. RESULTS: This innovative technique capitalizes on a new technology that increases the sensitivity of MRS detection of crucial metabolites in cancer cells. CONCLUSION: It is anticipated that this innovative approach will lead to improved methods, both for the diagnosis and staging of HCCs and for the facilitation of the development of enzyme targeted therapies and other therapeutic interventions.

Bcl-xL regulates mitochondrial energetics by stabilizing the inner membrane potential.

Mammalian Bcl-x(L) protein localizes to the outer mitochondrial membrane, where it inhibits apoptosis by binding Bax and inhibiting Bax-induced outer membrane permeabilization. Contrary to expectation, we found by electron microscopy and biochemical approaches that endogenous Bcl-x(L) also localized to inner mitochondrial cristae. Two-photon microscopy of cultured neurons revealed large fluctuations in inner mitochondrial membrane potential when Bcl-x(L) was genetically deleted or pharmacologically inhibited, indicating increased total ion flux into and out of mitochondria. Computational, biochemical, and genetic evidence indicated that Bcl-x(L) reduces futile ion flux across the inner mitochondrial membrane to prevent a wasteful drain on cellular resources, thereby preventing an energetic crisis during stress. Given that F(1)F(O)-ATP synthase directly affects mitochondrial membrane potential and having identified the mitochondrial ATP synthase ß subunit in a screen for Bcl-x(L)-binding partners, we tested and found that Bcl-x(L) failed to protect ß subunit-deficient yeast. Thus, by bolstering mitochondrial energetic capacity, Bcl-x(L) may contribute importantly to cell survival independently of other Bcl-2 family proteins.

The pivotal roles of mitochondria in cancer: Warburg and beyond and encouraging prospects for effective therapies.

Tumors usurp established metabolic steps used by normal tissues for glucose utilization and ATP production that rely heavily on mitochondria and employ a route that, although involving mitochondria, includes a much greater dependency on glycolysis. First described by Otto Warburg almost nine decades ago [1], this aberrant phenotype becomes more pronounced with increased tumor malignancy [2]. Thus, while maintaining their capacity for respiration, tumors "turn more parasitic" by enhancing their ability to scavenge glucose from their surroundings. With excess glucose at hand, tumors shunt their metabolic flux more toward glycolysis than do their normal cells of origin, a strategy that allows for their survival when oxygen is limiting while providing them a mechanism to poison their extra-cellular environment with acid, thus paving the way for invasion and metastasis. Significantly, tumors harness a crucial enzyme to regulate and support this destructive path--to entrap and channel glucose toward glycolysis. This enzyme is an isoform of hexokinase, referred to as hexokinase type II, and also in abbreviated form as HK-2 or HK II. Due to many-faceted molecular features at genetic, epigenetic, transcriptional, and enzymatic levels, including sub-cellular localization to mitochondria, HK-2 facilitates and promotes the high glycolytic tumor phenotype [3]. Thus, HK-2 represents a pivotal model gene or enzyme that tumors "select for" during tumorigenesis in order to facilitate their destructive path. In this review, we examine the roles played by mitochondrial bound HK-2 within the context of the highly choreographed metabolic roulette of malignant tumors. Recent studies that outline how the aberrant glycolytic flux can be subverted toward a more "normal" metabolic phenotype, and how the glycolytic flux affects the tumor microenvironment to facilitate tumor dissemination are also described, including how these very features can be harnessed in new metabolic targeting strategies to selectively debilitate tumors.

Mitochondrial matters of the brain: amyloid formation and Alzheimer's disease introduction.

In recent years mitochondria, as the most abundant organelles in animal and human cells, have come to the forefront of biomedical research as they are now recognized not only as the major producers of ATP needed to drive cellular functions critical for life, but they are also the instruments of cell death. Not surprisingly, therefore, mitochondria are now known to be involved in many different diseases ranging from those that affect millions worldwide to those that affect only a few, i.e., rare diseases. These diseases include in addition to cardio-myopathies and cancer also diseases that affect many other organs/tissues including the brain/nervous system, the latter diseases now commonly referred to as "neurodegenerative diseases". Specifically, the subject of this mini-review series focuses on the role of mitochondria in Alzheimer's disease, a major age related neurodegenerative disease that results in loss or decline of memory and other cognitive abilities. This devastating disease affects millions of Americans, and globally multi-millions with very grim predictions for the future. Although the molecular and gene-related details that underlie Alzheimer's disease remain to be clearly elucidated, mitochondria appear to be very intimately involved. The purpose of this mini-review series is to summarize how various investigators working on this subject envision the role(s) of mitochondria in Alzheimer's disease. The development of future therapies for this disease is likely to rely heavily on the new knowledge gained.

Mitochondrial matters of the heart: a plethora of regulatory modes to maintain function for a long lifetime.

The human/animal heart, comprised of cells called "myocytes" is an incredible organ that to remain beating must be fueled constantly via the hydrolysis of adenosine tri-phosphate (ATP). Deriving most of its ATP from mitochondrial oxidative phosphorylation (ox phos), and a smaller amount from "glycolysis", i.e., glucose conversion to pyruvate or lactate, the heart helps in the delivery of oxygen (via hemoglobin) to every organ/tissue in our body. Then, the empty (deoxy) hemoglobin returns to load more oxygen and the journey to tissues is repeated 24 h a day, year after year, until "death do us part". To support this essential "pumping" process the heart must work constantly, i.e., 70-80 years (life expectancy in the U.S.). This is a remarkable feat when compared with one of our most costly people-made technologies, i.e., automobiles (cars). In the past century, it was rare to see the family car survive more than 10-15 years unless it had been subjected to motor replacement surgery. Most were laid to rest at a much earlier age. Now, in this new millennium should a brilliant car manufacturer succeed in constructing a car engine as efficient as the human heart, each family member requiring a car would need only one per life time. With this in mind, one of the major future "matters of the heart" is to keep it pumping, not only for the current 70-80 year life span but much longer. To do this depends on, among other matters, the two processes noted above, i.e., oxidative phosphorylation and glycolysis. The former is strictly a mitochondrial process that works only in the presence of oxygen whereas glycolysis, dependent on mitochondrial bound hexokinase 2 (MB-HK-2), works either in the presence or absence of oxygen. In addition, the MB-HK 2 is anti-apoptotic and helps with other factors to retard cell death. Current estimates reveal that the human heart of an individual living 70-80 years will have undergone 2.5-3.0 billion beats, a feat that is energetically feasible only due to the heart cells' (cardiomyocytes) large population of mitochondria with bound HK-2.