Metabolic reprogramming of cancer-associated fibroblasts by TGF-β drives tumor growth: Connecting TGF-β signaling with “Warburg-like” cancer metabolism and L-lactate production

We have previously shown that a loss of stromal Cav-1 is a biomarker of poor prognosis in breast cancers. Mechanistically, a loss of Cav-1 induces the metabolic reprogramming of stromal cells, with increased autophagy/mitophagy, mitochondrial dysfunction and aerobic glycolysis. As a consequence, Cav-1-low CAFs generate nutrients (such as L-lactate) and chemical building blocks that fuel mitochondrial metabolism and the anabolic growth of adjacent breast cancer cells. It is also known that a loss of Cav-1 is associated with hyperactive TGF-β signaling. However, it remains unknown whether hyperactivation of the TGF-β signaling pathway contributes to the metabolic reprogramming of Cav-1-low CAFs. To address these issues, we overexpressed TGF-β ligands and the TGF-β receptor I (TGFβ-RI) in stromal fibroblasts and breast cancer cells. Here, we show that the role of TGF-β in tumorigenesis is compartment-specific, and that TGF-β promotes tumorigenesis by shifting cancer-associated fibroblasts toward catabolic metabolism. Importantly, the tumor-promoting effects of TGF-β are independent of the cell type generating TGF-β. Thus, stromal-derived TGF-β activates signaling in stromal cells in an autocrine fashion, leading to fibroblast activation, as judged by increased expression of myofibroblast markers, and metabolic reprogramming, with a shift toward catabolic metabolism and oxidative stress. We also show that TGF-β-activated fibroblasts promote the mitochondrial activity of adjacent cancer cells, and in a xenograft model, enhancing the growth of breast cancer cells, independently of angiogenesis. Conversely, activation of the TGF-β pathway in cancer cells does not influence tumor growth, but cancer cell-derived-TGF-β ligands affect stromal cells in a paracrine fashion, leading to fibroblast activation and enhanced tumor growth. In conclusion, ligand-dependent or cell-autonomous activation of the TGF-β pathway in stromal cells induces their metabolic reprogramming, with increased oxidative stress, autophagy/mitophagy and glycolysis, and downregulation of Cav-1. These metabolic alterations can spread among neighboring fibroblasts and greatly sustain the growth of breast cancer cells. Our data provide novel insights into the role of the TGF-β pathway in breast tumorigenesis, and establish a clear causative link between the tumor-promoting effects of TGF-β signaling and the metabolic reprogramming of the tumor microenvironment.     

Inhibitory effect of andrographolide from Andrographis paniculata on PAF-induced platelet aggregation.

Andrographolide, an active principle of the Chinese drug Andrographis paniculata, used for prevention and treatment of common cold in Scandinavia and known as an antiinflammatory, antiviral, antithrombotic, hypotensive and antiatherosclerotic drug, was investigated for its suggested influence on the biosynthesis of eicosanoids and the platelet-activating factor (PAF). Whereas in isolated human polymorph-nuclear leukocytes (PMNL) no influence on the biosynthesis was found, it could be shown that andrographolide inhibits PAF-induced human blood platelet aggregation in a dose dependent manner (IC50-5 microM). These results indicate that andrographolide has a mechanism of action different from that of non-steroidal antiinflammatory drugs (NSAID) and most likely associated with the cardiovascular and antithrombotic activity described of Andrographis paniculata.     

Cell Elasticity Is Regulated by the Tropomyosin Isoform Composition of the Actin Cytoskeleton

The actin cytoskeleton is the primary polymer system within cells responsible for regulating cellular stiffness. While various actin binding proteins regulate the organization and dynamics of the actin cytoskeleton, the proteins responsible for regulating the mechanical properties of cells are still not fully understood. In the present study, we have addressed the significance of the actin associated protein, tropomyosin (Tpm), in influencing the mechanical properties of cells. Tpms belong to a multi-gene family that form a co-polymer with actin filaments and differentially regulate actin filament stability, function and organization. Tpm isoform expression is highly regulated and together with the ability to sort to specific intracellular sites, result in the generation of distinct Tpm isoform-containing actin filament populations. Nanomechanical measurements conducted with an Atomic Force Microscope using indentation in Peak Force Tapping in indentation/ramping mode, demonstrated that Tpm impacts on cell stiffness and the observed effect occurred in a Tpm isoform-specific manner. Quantitative analysis of the cellular filamentous actin (F-actin) pool conducted both biochemically and with the use of a linear detection algorithm to evaluate actin structures revealed that an altered F-actin pool does not absolutely predict changes in cell stiffness. Inhibition of non-muscle myosin II revealed that intracellular tension generated by myosin II is required for the observed increase in cell stiffness. Lastly, we show that the observed increase in cell stiffness is partially recapitulated in vivo as detected in epididymal fat pads isolated from a Tpm3.1 transgenic mouse line. Together these data are consistent with a role for Tpm in regulating cell stiffness via the generation of specific populations of Tpm isoform-containing actin filaments.     

Intact fetal ovarian cord formation promotes mouse oocyte survival and development

Background  

Female reproductive potential, or the ability to propagate life, is limited in mammals with the majority of oocytes lost before birth. In mice, surviving perinatal oocytes are enclosed in ovarian follicles for subsequent oocyte development and function in the adult. Before birth, fetal germ cells of both sexes develop in clusters, or germline cysts, in the undifferentiated gonad. Upon sex determination of the fetal gonad, germ cell cysts become organized into testicular or ovarian cord-like structures and begin to interact with gonadal somatic cells. Although germline cysts and testicular cords are required for spermatogenesis, the role of cyst and ovarian cord formation in mammalian oocyte development and female fertility has not been determined.     

Behavioral correlations across breeding contexts provide a mechanism for a cost of aggression

Identifying correlations among behaviors is important for understandinghow selection shapes the phenotype. Correlated behaviors canindicate constraints on the evolution of behavioral plasticityor may reflect selection for functional integration among behaviors.Obligate cavity-nesting birds provide an opportunity to examinethese correlations because males must defend limited nest cavitieswhile also competing for mating opportunities and providingparental care. Here, I investigated the role of behavioral correlationsin producing a counterintuitive relationship between nest defenseand reproductive success in western bluebirds (Sialia mexicana)such that males that defended their nests most intensely hadthe lowest reproductive success, measured as the number of withinand extrapair offspring that fledged. By experimentally measuringaggression across contexts, I show that this cost of nest defensewas due to the correlated expression of aggression across thecontexts of nest defense and male–male competition coupledwith a trade-off between male–male aggression and parentalcare. In particular, more aggressive males provisioned theirfemales less during incubation and this led to disrupted incubationpatterns and fewer fledged offspring. However, aggressive malesdid not benefit from avoiding parental investment by gainingextrapair fertilizations, and thus, it is unclear how high levelsof aggression are maintained in this population despite apparentcosts. These results suggest that there are constraints to theevolution of plasticity in aggression and emphasize the importanceof considering the integrated behavioral phenotype to understandhow variation in behavior is linked to fitness.     

Analysis of post-translational modifications in Alzheimer's disease by mass spectrometry

The roles of post-translational modifications (PTMs) in the onset and progression of disease have been extensively studied for decades. More specifically, various PTMs have been the focus of research in Alzheimer's disease (AD). The two most discussed hallmarks of the disease, senile plaques and tau tangles, are the result of PTMs of the amyloidβ protein precursor (AβPP) and the microtubule stabilizing protein: tau. While these modifications have been characterized indirectly by biochemical-based methods, the primary shortcoming to this research can be linked to a lack of a thorough molecular-based means of qualitative and quantitative analysis of many of these modifications within transgenic animal, and human samples. In this review, we discuss the important proteins and their associated PTMs linked to AD and the ways in which mass spectrometry has and will be utilized to analyze them. We also comment on novel ways in which molecular-based mass spectrometry methods should be employed going forward to resolve the interconnections of the PTMs involvement in various stages of AD pathology (preclinical, mild cognitive impairment, advanced-stage AD).     

Premature refutation of a human-mediated marine species introduction: the case history of the marine snail <Emphasis Type="Italic">Littorina littorea</Emphasis> in the Northwestern Atlantic

The closely documented spread of the European periwinkle snail, Littorina littorea from Pictou, Nova Scotia in 1840 to New Jersey by 1870, its near absence in pre-European fossil deposits, and its close association with human mechanisms of transport from Europe, are among the clearest evidence of a human-mediated marine introduction ever reported. Genetic data were recently proposed as evidence that North American L. littorea predate European contact and thus, are not introduced. Review of these genetic data and all other data reveals that the simplest explanation of the modern occurrence of this snail in North America is by human introduction.     

dam methylation and the initiation of DNA replication on oriC plasmids

Summary Plasmid DNA containing the replication origin of the Escherichia coli chromosome (oriC) has been shown to be inefficient as a template for DNA synthesis in vitro when isolated from dam mutants. here, we extend this study to hemimethylated oriC plasmids and to replication in dam-3 mutant enzyme extracts. The results show that: (1) hemimethylated oriC plasmids replicate with the same low efficiency as nonmethylated DNA; (2) DNA synthesis starts at oriC regardless of the methylated state of the template; (3) replication in dam-3 enzyme extracts is inefficient because this strain is deficient in DnaA protein; and (4) consistent with this observation, the copy number of the oriC plasmid pFH271 is reduced in the dam-3 mutant. However, we have found that low DnaA protein levels in dam-3 mutants are not sufficient to explain the reduced transformation efficiency of oriC plasmids. We suggest that there must exist in vivo inhibitory factors not present or present in low quantities in vitro which specifically recognize the hemimethylated or nonmethylated forms of the oric region.