When fighting cancer, knowledge on metabolism has always been important. Today, it matters more than ever. The restricted cataloging of cancer genomes is quite unlikely to achieve the task of curing ...cancer, unless it is integrated into metabolic networks that respond to and influence the constantly evolving cancer stem cell (CSC) cellular states. Once the genomic era of carcinogenesis had pushed the 1920s Otto Warburg's metabolic cancer hypothesis into obscurity for decades, the most recent studies begin to support a new developing paradigm, in which the molecular logic behind the conversion of non-CSCs into CSCs can be better understood in terms of the "metabolic facilitators" and "metabolic impediments" that operate as proximate openings and roadblocks, respectively, for the transcriptional events and signal transduction programs that ultimately orchestrate the intrinsic and/or microenvironmental paths to CSC cellular states. Here we propose that a profound understanding of how human carcinomas install a proper "Warburg effect version 2.0" allowing them to "run" the CSCs' "software" programs should guide a new era of metabolo-genomic-personalized cancer medicine. By viewing metabolic reprogramming of CSCs as an essential characteristic that allows dynamic, multidimensional and evolving cancer populations to compete successfully for their expansion on the organism, we now argue that CSCs bioenergetics might be another cancer hallmark. A definitive understanding of metabolic reprogramming in CSCs may complement or to some extent replace, the 30-y-old paradigm of targeting oncogenes to treat human carcinomas, because it can be possible to metabolically create non-permissive or "hostile" metabotypes to prevent the occurrence of CSC cellular states with tumor- and metastasis-initiating capacity.
Transforming Growth Factor-b (TGFb) is a major driving force of the Epithelial-to-Mesenchymal (EMT) genetic program, which becomes overactive in the pathophysiology of many age-related human ...diseases. TGFb-driven EMT is sufficient to generate migrating cancer stem cells by directly linking the acquisition of cellular motility with the maintenance of tumor-initiating (stemness) capacity. Chronic diseases exhibiting excessive fibrosis can be caused by repeated and sustained infliction of TGFb-driven EMT, which increases collagen and extracellular matrix synthesis. Pharmacological prevention and/or reversal of TGFb-induced EMT may therefore have important clinical applications in the management of cancer metastasis as well as in the prevention and/or treatment of end-state organ failures. Earlier studies from our group have revealed that clinically-relevant concentrations of the biguanide derivative metformin, the most widely used oral agent to lower blood glucose concentration in patients with type 2 diabetes and metabolic syndrome, notably decreased both the self-renewal and the proliferation of trastuzumab-refractory breast cancer stem cell populations. Given that: a.) tumor-initiating cancer stem cells display a significant enrichment in the expression of basal/mesenchymal or myoepithelial markers, including an increased secretion of TGFb; b.) metformin treatment impedes the ontogeny of generating the stem cell phenotype by transcriptionally repressing key drivers of the EMT genetic program (e.g. ZEB1, TWIST1, SNAIL2 Slug, TGFbs), we recently hypothesized that prevention of TGFb-induced EMT might represent a common molecular mechanism underlying the anti-cancer stem cells and anti-fibrotic actions of metformin. Remarkably, metformin exposure not only impedes TGFb-promoted loss of the epithelial marker E-cadherin in MCF-7 breast cancer cells but it prevents further TGF-induced cell scattering and accumulation of the mesenchymal marker vimentin in Madin-Darby canine kidney (MDCK) cells. We now propose that metformin, by weakening the ability of TGFb signaling to fully induce mesenchymal cell states in a variety of pathological processes including fibrosis (e.g. chronic renal disease, non-alcoholic steatohepatitis, heart failure or sclerosis) and malignant progression (and likely by reducing TGFb-regulated inflammation and immune responses -inflamm-aging-), molecularly behaves as a bona fide anti-aging modality.
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal dominant genetic disorder of the small arteries that causes ischemic vascular ...events, subcortical dementia, behavioral changes, and migraine-like headaches. It is caused by a mutation in the NOTCH3 gene; this disease was first described in 1955 by van Bogaert. We present a 29-year-old woman who presented to the neurology department. She has no history of chronic degenerative diseases. She has been complaining of migraine-like headaches for the past six months. She has cognitive impairment with arithmetic and executive function deficits on neurological examination. Blood biometry and blood chemistry are within normal parameters in her laboratory studies. A viral panel and immunological profile were also performed and were not reactive. A lumbar puncture was performed, and the composition of the cerebrospinal fluid was within normal limits. An MRI was performed, which showed bilateral and symmetric white matter hyperintensities consistent with CADASIL syndrome. There is no specific treatment. Management of these patients is based on symptom control. Neurological sequelae have an important impact on the quality of life and mortality of these patients. For this reason, pharmacological preventive therapies have been sought with controversial evidence.
Glucose deprivation is a distinctive feature of the tumor microecosystem caused by the imbalance between poor supply and an extraordinarily high consumption rate. The metabolic reprogramming from ...mitochondrial respiration to aerobic glycolysis in cancer cells (the "Warburg effect") is linked to oncogenic transformation in a manner that frequently implies the inactivation of metabolic checkpoints such as the energy rheostat AMP-activated protein kinase (AMPK). Because the concept of synthetic lethality in oncology can be applied not only to genetic and epigenetic intrinsic differences between normal and cancer cells but also to extrinsic ones such as altered microenvironment, we recently hypothesized that stress-energy mimickers such as the AMPK agonist metformin should produce metabolic synthetic lethality in a glucose-starved cell culture milieu imitating the adverse tumor growth conditions in vivo. Under standard high-glucose conditions, metformin supplementation mostly caused cell cycle arrest without signs of apoptotic cell death. Under glucose withdrawal stress, metformin supplementation circumvented the ability of oncogenes (e.g., HER2) to protect breast cancer cells from glucose-deprivation apoptosis. Significantly, representative cell models of breast cancer heterogeneity underwent massive apoptosis (by > 90% in some cases) when glucose-starved cell cultures were supplemented with metformin. Our current findings may uncover crucial issues regarding the cell-autonomous metformin's anti-cancer actions: (1) The offently claimed clinically irrelevant, non-physiological concentrations needed to observe the metformin's anti-cancer effects in vitro merely underlie the artifactual interference of erroneous glucose-rich experimental conditions that poorly reflect glucose-starved in vivo conditions; (2) the preferential killing of cancer stem cells (CSC) by metformin may simply expose the best-case scenario for its synthetically lethal activity because an increased dependency on Warburg-like aerobic glycolysis (hyperglycolytic phenotype) is critical to sustain CSC stemness and immortality; (3) the microenvironment-mediated contextual synthetic lethality of metformin should be expected to enormously potentiate the anti-cancer effect of anti-angiogenesis agents that promote severe oxygen and glucose deprivation in certain areas of the tumor tissues.
Molecular controllers of the number and function of tissue stem cells may share common regulatory pathways for the nuclear reprogramming of somatic cells to become induced Pluripotent Stem Cells ...(iPSCs). If this hypothesis is true, testing the ability of longevity-promoting chemicals to improve reprogramming efficiency may provide a proof-of-concept validation tool for pivotal housekeeping pathways that limit the numerical and/or functional decline of adult stem cells. Reprogramming is a slow, stochastic process due to the complex and apparently unrelated cellular processes that are involved. First, forced expression of the Yamanaka cocktail of stemness factors, OSKM, is a stressful process that activates apoptosis and cellular senescence, which are the two primary barriers to cancer development and somatic reprogramming. Second, the a priori energetic infrastructure of somatic cells appears to be a crucial stochastic feature for optimal successful routing to pluripotency. If longevity-promoting compounds can ablate the drivers and effectors of cellular senescence while concurrently enhancing a bioenergetic shift from somatic oxidative mitochondria toward an alternative ATP-generating glycolytic metabotype, they could maximize the efficiency of somatic reprogramming to pluripotency. Support for this hypothesis is evidenced by recent findings that well-characterized mTOR inhibitors and autophagy activators (e.g., PP242, rapamycin and resveratrol) notably improve the speed and efficiency of iPSC generation. This article reviews the existing research evidence that the most established mTOR inhibitors can notably decelerate the cellular senescence that is imposed by DNA damage-like responses, which are somewhat equivalent to the responses caused by reprogramming factors. These data suggest that fine-tuning mTOR signaling can impact mitochondrial dynamics to segregate mitochondria that are destined for clearance through autophagy, which results in the loss of mitochondrial function and in the accelerated onset of the glycolytic metabolism that is required to fuel reprogramming. By critically exploring how mTOR-regulated senescence, bioenergetic infrastructure and autophagy can actively drive the reprogramming of somatic cells to pluripotency, we define a metabolic roadmap that may be helpful for designing pharmacological and behavioral interventions to prevent or retard the dysfunction/exhaustion of aging stem cell populations.
Coenzyme Q10 (CoQ10) is a redox molecule critical for the proper function of energy metabolism and antioxidant defenses. Despite its essential role in cellular metabolism, the regulation of CoQ10 ...biosynthesis in humans remains mostly unknown. Herein, we determined that PPTC7 is a regulatory protein of CoQ10 biosynthesis required for human cell survival. We demonstrated by in vitro approaches that PPTC7 is a bona fide protein phosphatase that dephosphorylates the human COQ7. Expression modulation experiments determined that human PPTC7 dictates cellular CoQ10 content. Using two different approaches (PPTC7 over-expression and caloric restriction), we demonstrated that PPTC7 facilitates and improves the human cell adaptation to respiratory conditions. Moreover, we determined that the physiological role of PPTC7 takes place in the adaptation to starvation and pro-oxidant conditions, facilitating the induction of mitochondrial metabolism while preventing the accumulation of ROS. Here we unveil the first post-translational mechanism regulating CoQ10 biosynthesis in humans and propose targeting the induction of PPTC7 activity/expression for the treatment of CoQ10-related mitochondrial diseases.
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•The human gene PPTC7 encodes for a mitochondrial phosphatase of the PPM family.•COQ7, a protein involved in CoQ10 biosynthesis, is target in vitro of PPTC7.•PPTC7 regulates CoQ10 biosynthesis in human cells.•Decreased levels of glucose increase PPTC7 expression in HeLa cells.•PPTC7 overexpression improves mitochondrial metabolism.
A low incidence of breast cancer in the Mediterranean basin suggests that a high consumption of Extra Virgin Olive Oil (EVOO) might confer this benefit. While the anti-HER2 oncogene effects of the ...main omega-9 fatty acid present in EVOO triacylglycerols (i.e., oleic acid) have been recently described, the anti-breast cancer activities of EVOO non-glyceridic constituents--which consist of at least 30 phenolic compounds--remained to be evaluated.
Semi-preparative HPLC was used to isolate EVOO polyphenols (i.e., tyrosol, hydroxytyrosol, oleuropein). Both the anti-proliferative and the pro-apoptotic effects of EVOO phenolics were evaluated by using MTT-based quantification of metabolically viable cells and ELISA-based detection of histone-associated DNA fragments, respectively. The nature of the interaction between oleuropein aglycone and the anti-HER2 monoclonal antibody trastuzumab (Herceptin) was mathematically evaluated by the dose-oriented isobologram technique. HER2-specific ELISAs were employed to quantitatively assess both the basal cleavage of the HER2 extracellular domain (ECD) and the expression level of total HER2. The activation status of HER2 was evaluated by immunoblotting procedures using a monoclonal antibody specifically recognizing the tyrosine phosphorylated (Phosphor-Tyr1248) form of HER2.
Among EVOO polyphenols tested, oleuropein aglycone was the most potent EVOO phenolic in decreasing breast cancer cell viability. HER2 gene-amplified SKBR3 cells were ~5-times more sensitive to oleuropein aglycone than HER2-negative MCF-7 cells. Retroviral infection of the HER2 oncogene in MCF-7 cells resulted in a "SKBR3-assimilated" phenotype of hypersensitivity to oleuropein aglycone. An up to 50-fold increase in the efficacy of trastuzumab occurred in the presence of oleuropein aglycone. A preclinical model of acquired autoresistance to trastuzumab (SKBR3/Tzb100 cells) completely recovered trastuzumab sensitivity (> 1,000-fold sensitization) when co-cultured in the presence of oleuropein aglycone. Indeed, the nature of the interaction between oleuropein aglycone and trastuzumab was found to be strongly synergistic in Tzb-resistant SKBR3/Tzb100 cells. Mechanistically, oleuropein aglycone treatment significantly reduced HER2 ECD cleavage and subsequent HER2 auto-phosphorylation, while it dramatically enhanced Tzb-induced down-regulation of HER2 expression.
Olive oil's bitter principle (i.e., oleuropein aglycone) is among the first examples of how selected nutrients from an EVOO-rich "Mediterranean diet" directly regulate HER2-driven breast cancer disease.
The characterization and quantification of extra-virgin olive oil (EVOO) phenolic compounds by a rapid resolution liquid chromatography (RRLC) method coupled to diode-array and time of flight mass ...spectrometry (TOF) detection systems was developed. The RRLC method transferred from a conventional HPLC one achieved better performance with shorter analysis times. The phenolic compounds were separated with a C18 column (150 mm
×
4.6
mm, 1.8
μm) using water with 0.5% acetic acid and acetonitrile as mobile phases. Good peak resolution was obtained and 19 different phenols were identified in less than 20
min providing a new level of information about the samples in shorter time. The applicability of this analytical approach was confirmed by the successful analysis of three different EVOO varieties (Picual, Hojiblanca, and Arbequina) obtained from different trademarks. Besides identification of the most important phenolic compounds and their quantification in three different ways (RRLC-UV, RRLC-MS and a new approach using the total polyphenol content obtained with Folin Ciocalteau, the relative areas and the response factors), we also described the occurrence of correlations between the phenolic composition of EVOO-derived crude phenolic extracts and their anti-proliferative abilities toward human breast cancer-derived cell lines. When compared with lignans-rich EVOO varieties, secoiridoids-rich EVOO had a significantly strong ability to alter cell viability in four different types of human breast carcinoma cells.
Energy metabolism plasticity enables stemness programs during the reprogramming of somatic cells to an induced pluripotent stem cell (iPSC) state. This relationship may introduce a new era in the ...understanding of Warburg's theory on the metabolic origin of cancer at the level of cancer stem cells (CSCs). Here, we used Yamanaka's stem cell technology in an attempt to create stable CSC research lines in which to dissect the transcriptional control of mTOR-the master switch of cellular catabolism and anabolism-in CSC-like states. The rare colonies with iPSC-like morphology, obtained following the viral transduction of the Oct4, Sox2, Klf4, and c-Myc (OSKM) stemness factors into MCF-7 luminal-like breast cancer cells (MCF-7/Rep), demonstrated an intermediate state between cancer cells and bona fide iPSCs. MCF-7/Rep cells notably overexpressed SOX2 and stage-specific embryonic antigen (SSEA)-4 proteins; however, other stemness-related markers (OCT4, NANOG, SSEA-1, TRA-1-60, and TRA-1-81) were found at low to moderate levels. The transcriptional analyses of OSKM factors confirmed the strong but unique reactivation of the endogenous Sox2 stemness gene accompanied by the silencing of the exogenous Sox2 transgene in MCF-7/Rep cells. Some but not all MCF-7/Rep cells acquired strong alkaline phosphatase (AP) activity compared with MCF-7 parental cells. SOX2-overexpressing MCF-7/Rep cells contained drastically higher percentages of CD44
+
and ALDEFLUOR-stained ALDH
bright
cells than MCF-7 parental cells. The overlap between differentially expressed mTOR signaling-related genes in 3 different SOX2-overexpressing CSC-like cell lines revealed a notable downregulation of 3 genes, PRKAA1 (which codes for the catalytic α 1 subunit of AMPK), DDIT4/REDD1 (a stress response gene that operates as a negative regulator of mTOR), and DEPTOR (a naturally occurring endogenous inhibitor of mTOR activity). The insulin-receptor gene (INSR) was differentially upregulated in MCF-7/Rep cells. Consistent with the downregulation of AMPK expression, immunoblotting procedures confirmed upregulation of p70S6K and increased phosphorylation of mTOR in Sox2-overexpressing CSC-like cell populations. Using an in vitro model of the de novo generation of CSC-like states through the nuclear reprogramming of an established breast cancer cell line, we reveal that the transcriptional suppression of mTOR repressors is an intrinsic process occurring during the acquisition of CSC-like properties by differentiated populations of luminal-like breast cancer cells. This approach may provide a new path for obtaining information about preventing the appearance of CSCs through the modulation of the AMPK/mTOR pathway.
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