Reprogramming of differentiated cells into pluripotent cells can occur in vivo, but the mechanisms involved remain to be elucidated. Senescence is a cellular response to damage, characterized by ...abundant production of cytokines and other secreted factors that, together with the recruitment of inflammatory cells, result in tissue remodeling. Here, we show that in vivo expression of the reprogramming factors OCT4, SOX2, KLF4, and cMYC (OSKM) in mice leads to senescence and reprogramming, both coexisting in close proximity. Genetic and pharmacological analyses indicate that OSKM-induced senescence requires the Ink4a/Arf locus and, through the production of the cytokine interleukin-6, creates a permissive tissue environment for in vivo reprogramming. Biological conditions linked to senescence, such as tissue injury or aging, favor in vivo reprogramming by OSKM. These observations may be relevant for tissue repair.
Genetic overexpression of protein deacetylase Sir2 increases longevity in a variety of lower organisms, and this has prompted interest in the effects of its closest mammalian homologue, Sirt1, on ...ageing and cancer. We have generated transgenic mice moderately overexpressing Sirt1 under its own regulatory elements (Sirt1-tg). Old Sirt1-tg mice present lower levels of DNA damage, decreased expression of the ageing-associated gene p16(Ink4a), a better general health and fewer spontaneous carcinomas and sarcomas. These effects, however, were not sufficiently potent to affect longevity. To further extend these observations, we developed a metabolic syndrome-associated liver cancer model in which wild-type mice develop multiple carcinomas. Sirt1-tg mice show a reduced susceptibility to liver cancer and exhibit improved hepatic protection from both DNA damage and metabolic damage. Together, these results provide direct proof of the anti-ageing activity of Sirt1 in mammals and of its tumour suppression activity in ageing- and metabolic syndrome-associated cancer.
Aging in worms and flies is regulated by the PI3K/Akt/Foxo pathway. Here we extend this paradigm to mammals. Ptentg mice carrying additional genomic copies of Pten are protected from cancer and ...present a significant extension of life span that is independent of their lower cancer incidence. Interestingly, Ptentg mice have an increased energy expenditure and protection from metabolic pathologies. The brown adipose tissue (BAT) of Ptentg mice is hyperactive and presents high levels of the uncoupling protein Ucp1, which we show is a target of Foxo1. Importantly, a synthetic PI3K inhibitor also increases energy expenditure and hyperactivates the BAT in mice. These effects can be recapitulated in isolated brown adipocytes and, moreover, implants of Ptentg fibroblasts programmed with Prdm16 and Cebpβ form subcutaneous brown adipose pads more efficiently than wild-type fibroblasts. These observations uncover a role of Pten in promoting energy expenditure, thus decreasing nutrient storage and its associated damage.
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► A modest systemic increase in Pten activity extends longevity in mice ► Mice overexpressing Pten are protected from metabolic damage and cancer ► Pten positively regulates energy expenditure and brown adipose function ► Pharmacological PI3K inhibitors increase brown adipose activity
NOTCH signaling suppresses tumor growth and proliferation in several types of stratified epithelia. Here, we show that missense mutations in NOTCH1 and NOTCH2 found in human bladder cancers result in ...loss of function. In murine models, genetic ablation of the NOTCH pathway accelerated bladder tumorigenesis and promoted the formation of squamous cell carcinomas, with areas of mesenchymal features. Using bladder cancer cells, we determined that the NOTCH pathway stabilizes the epithelial phenotype through its effector HES1 and, consequently, loss of NOTCH activity favors the process of epithelial-mesenchymal transition. Evaluation of human bladder cancer samples revealed that tumors with low levels of HES1 present mesenchymal features and are more aggressive. Together, our results indicate that NOTCH serves as a tumor suppressor in the bladder and that loss of this pathway promotes mesenchymal and invasive features.
Senescent cells accumulate in multiple aging‐associated diseases, and eliminating these cells has recently emerged as a promising therapeutic approach. Here, we take advantage of the high lysosomal ...β‐galactosidase activity of senescent cells to design a drug delivery system based on the encapsulation of drugs with galacto‐oligosaccharides. We show that gal‐encapsulated fluorophores are preferentially released within senescent cells in mice. In a model of chemotherapy‐induced senescence, gal‐encapsulated cytotoxic drugs target senescent tumor cells and improve tumor xenograft regression in combination with palbociclib. Moreover, in a model of pulmonary fibrosis in mice, gal‐encapsulated cytotoxics target senescent cells, reducing collagen deposition and restoring pulmonary function. Finally, gal‐encapsulation reduces the toxic side effects of the cytotoxic drugs. Drug delivery into senescent cells opens new diagnostic and therapeutic applications for senescence‐associated disorders.
Synopsis
Senescent cells are present in many diseases where they play an active pathological role. A common feature of senescent cells is their high content of lysosomes. Here, it is reported a pharmacological vehicle with lysosomal tropism that preferentially releases drugs into senescent cells.
Drugs encapsulated with galacto‐oligosaccharides (gal‐encapsulation) are released into cells after digestion with lysosomal β‐galactosidase and this happens more efficiently in senescent cells.
After intravenous injection, gal‐encapsulated drugs preferentially deliver their cargo into pathological tissues with high content of senescent cells.
Gal‐encapsulated doxorubicin ameliorates lung fibrosis in mice, reducing collagen and recovering normal breathing, and this is in contrast to free doxorubicin.
When xenograft tumors in mice are treated with chemotherapy, a fraction of tumor cells undergo senescence, and concomitant treatment with gal‐encapsulated doxorubicin results in full tumor regression.
Gal‐encapsulation prevents the exposure of non‐pathological tissues to drugs and therefore reduces their associated toxicities, as it is shown for doxorubicin cardiotoxicity and for navitoclax‐induced thrombocytopenia.
Senescent cells are present in many diseases where they play an active pathological role. A common feature of senescent cells is their high content of lysosomes. Here, it is reported a pharmacological vehicle with lysosomal tropism that preferentially releases drugs into senescent cells.
Here, we have investigated the role of the Notch pathway in the generation and maintenance of KrasG12V-driven non-small cell lung carcinomas (NSCLCs). We demonstrate by genetic means that γ-secretase ...and RBPJ are essential for the formation of NSCLCs. Of importance, pharmacologic treatment of mice carrying autochthonous NSCLCs with a γ-secretase inhibitor (GSI) blocks cancer growth. Treated carcinomas present reduced HES1 levels and reduced phosphorylated ERK without changes in phosphorylated MEK. Mechanistically, we show that HES1 directly binds to and represses the promoter of DUSP1, encoding a dual phosphatase that is active against phospho-ERK. Accordingly, GSI treatment upregulates DUSP1 and decreases phospho-ERK. These data provide proof of the in vivo therapeutic potential of GSIs in primary NSCLCs.
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► The canonical Notch pathway is needed for KrasG12V-driven NSCLCs formation ► Pharmacological inhibition of γ-secretase in vivo arrests primary NSCLCs ► Inhibition of γ-secretase induces phosphatase DUSP1 and reduces ERK phosphorylation ► The Notch effector HES1 binds to the DUSP1 promoter and inhibits its expression
Genetic inhibition of PI3K signaling increases energy expenditure, protects from obesity and metabolic syndrome, and extends longevity. Here, we show that two pharmacological inhibitors of PI3K, ...CNIO-PI3Ki and GDC-0941, decrease the adiposity of obese mice without affecting their lean mass. Long-term treatment of obese mice with low doses of CNIO-PI3Ki reduces body weight until reaching a balance that is stable for months as long as the treatment continues. CNIO-PI3Ki treatment also ameliorates liver steatosis and decreases glucose serum levels. The above observations have been recapitulated in independent laboratories and using different oral formulations of CNIO-PI3Ki. Finally, daily oral treatment of obese rhesus monkeys for 3 months with low doses of CNIO-PI3Ki decreased their adiposity and lowered their serum glucose levels, in the absence of detectable toxicities. Therefore, pharmacological inhibition of PI3K is an effective and safe anti-obesity intervention that could reverse the negative effects of metabolic syndrome in humans.
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•Treatment of obese mice with PI3K inhibitors reduces obesity and metabolic syndrome•Weight loss induced by PI3K inhibitors is due to a decrease in adiposity•Chronic PI3K inhibition did not result in drug resistance or toxic effects•Treatment of obese monkeys with PI3K inhibitors is safe and reduces adiposity
Ortega-Molina et al. investigate pharmacological PI3K inhibition in obese mice and rhesus monkeys, and conclude that pharmacological inhibition of PI3K is an effective and safe anti-obesity intervention that reverses metabolic syndrome.
Partial inhibition of PI3K is one of the best-validated and evolutionary conserved manipulations to extend longevity. The best known health beneficial effects of reduced PI3K are related to ...metabolism and include increased energy expenditure, reduced nutrient storage, and protection from obesity. We have previously shown that a dual chemical inhibitor of the alpha and delta PI3K isoforms (CNIO-PI3Ki) reduces obesity in mice and monkeys, without evident toxic effects after long-term treatment. Here, we dissect the role of the alpha and delta PI3K isoforms by making use of selective inhibitors against PI3Kα (BYL-719 also known as alpelisib) or PI3Kδ (GS-9820 also known as acalisib). Treatment of mice with the above mentioned inhibitors indicated that BYL-719 increases energy expenditure in normal mice and efficiently reduces body weight in obese (ob/ob) mice, whereas these effects were not observed with GS-9820. Of note, the dose of BYL-719 required to reduce obesity was 10x higher than the equivalent dose of CNIO-PI3Ki, which could suggest that simultaneous inhibition of PI3K alpha and delta is more beneficial than single inhibition of the alpha isoform. In summary, we conclude that inhibition of PI3Kα is sufficient to increase energy expenditure and reduce obesity, and suggest that concomitant PI3Kα inhibition could play an auxiliary role.
Abstract
Fasting is a physiological stress that elicits well-known metabolic adaptations, however, little is known about the role of stress-responsive tumor suppressors in fasting. Here, we have ...examined the expression of several tumor suppressors upon fasting in mice. Interestingly,
p21
mRNA is uniquely induced in all the tissues tested, particularly in liver and muscle (>10 fold) and this upregulation is independent of p53. Remarkably, in contrast to wild-type mice,
p21
-null mice become severely morbid after prolonged fasting. The defective adaptation to fasting of
p21
-null mice is associated to elevated energy expenditure, accelerated depletion of fat stores and premature activation of protein catabolism in the muscle. Analysis of the liver transcriptome and cell-based assays revealed that the absence of p21 partially impairs the transcriptional program of PPARα, a key regulator of fasting metabolism. Finally, treatment of
p21
-null mice with a PPARα agonist substantially protects them from their accelerated loss of fat upon fasting. We conclude that p21 plays a relevant role in fasting adaptation through the positive regulation of PPARα.
Pluripotent stem cells (PSCs) transition between cell states in vitro, reflecting developmental changes in the early embryo. PSCs can be stabilized in the naive state by blocking extracellular ...differentiation stimuli, particularly FGF-MEK signalling. Here, we report that multiple features of the naive state in human and mouse PSCs can be recapitulated without affecting FGF-MEK signalling or global DNA methylation. Mechanistically, chemical inhibition of CDK8 and CDK19 (hereafter CDK8/19) kinases removes their ability to repress the Mediator complex at enhancers. CDK8/19 inhibition therefore increases Mediator-driven recruitment of RNA polymerase II (RNA Pol II) to promoters and enhancers. This efficiently stabilizes the naive transcriptional program and confers resistance to enhancer perturbation by BRD4 inhibition. Moreover, naive pluripotency during embryonic development coincides with a reduction in CDK8/19. We conclude that global hyperactivation of enhancers drives naive pluripotency, and this can be achieved in vitro by inhibiting CDK8/19 kinase activity. These principles may apply to other contexts of cellular plasticity.
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