Lactate-Mediated Epigenetic Reprogramming Regulates Formation of Human Pancreatic Cancer-Associated Fibroblasts

Even though pancreatic ductal adenocarcinoma (PDAC) is associated with fibrotic stroma, the molecular pathways regulating the formation of cancer associated fibroblasts (CAFs) are not well elucidated. An epigenomic analysis of patient-derived and de-novo generated CAFs demonstrated widespread loss of cytosine methylation that was associated with overexpression of various inflammatory transcripts including CXCR4. Co-culture of neoplastic cells with CAFs led to increased invasiveness that was abrogated by inhibition of CXCR4. Metabolite tracing revealed that lactate produced by neoplastic cells leads to increased production of alpha-ketoglutarate (aKG) within mesenchymal stem cells (MSCs). In turn, aKG mediated activation of the demethylase TET enzyme led to decreased cytosine methylation and increased hydroxymethylation during de novo differentiation of MSCs to CAF. Co-injection of neoplastic cells with TET-deficient MSCs inhibited tumor growth in vivo. Thus, in PDAC, a tumor-mediated lactate flux is associated with widespread epigenomic reprogramming that is seen during CAF formation

An approach to lens regeneration in mice following lentectomy and the implantation of a biodegradable hydrogel encapsulating iris pigmented tissue in combination with basic fibroblast growth factor

Organ or tissue regeneration is the process by which damaged or lost tissue parts or whole body organs are repaired or replaced. When compared to amphibians, mammals possess very limited regenerative capabilities. Mammals are capable of lens regeneration following lentectomy only if the lens capsule is left behind. Regeneration is achieved by the residual lens epithelial cells (LECs) adherent to the remaining lens capsule. Urodele amphibians, however, have been reported to regenerate their lenses, following whole organ removal, by the transdifferentiation of the pigmented epithelial cells (PECs) of the dorsal iris. These cells, namely PECs, have been shown to possess a potential for transdifferentiation in vitro as well as in vivo. In this study, the feasibility of coaxing iris PECs to regenerate a lens in vivo was tested by encapsulating an iris pigmented epithelial tissue by a hydrogel bead combined with FGF and implanting the resulting matrix in lentectomized mice. This study also investigates the ability of aligned Poly-ε-caprolactone (PCL) nanofibers in inducing the differentiation of LECs and the subsequent alignment of lens fiber cells

An approach to lens regeneration in mice following lentectomy and the implantation of a biodegradable hydrogel encapsulating iris pigmented tissue in combination with basic fibroblast growth factor

Organ or tissue regeneration is the process by which damaged or lost tissue parts or whole body organs are repaired or replaced. When compared to amphibians, mammals possess very limited regenerative capabilities. Mammals are capable of lens regeneration following lentectomy only if the lens capsule is left behind. Regeneration is achieved by the residual lens epithelial cells (LECs) adherent to the remaining lens capsule. Urodele amphibians, however, have been reported to regenerate their lenses, following whole organ removal, by the transdifferentiation of the pigmented epithelial cells (PECs) of the dorsal iris. These cells, namely PECs, have been shown to possess a potential for transdifferentiation in vitro as well as in vivo. In this study, the feasibility of coaxing iris PECs to regenerate a lens in vivo was tested by encapsulating an iris pigmented epithelial tissue by a hydrogel bead combined with FGF and implanting the resulting matrix in lentectomized mice. This study also investigates the ability of aligned Poly-ε-caprolactone (PCL) nanofibers in inducing the differentiation of LECs and the subsequent alignment of lens fiber cells

HSulf-1 deficiency dictates a metabolic reprograming of glycolysis and TCA cycle in ovarian cancer

Mondal S, Roy D, Camacho-Pereira J, et al. HSulf-1 deficiency dictates a metabolic reprograming of glycolysis and TCA cycle in ovarian cancer. ONCOTARGET. 2015;6(32):33705-33719.Warburg effect has emerged as a potential hallmark of many cancers. However, the molecular mechanisms that led to this metabolic state of aerobic glycolysis, particularly in ovarian cancer (OVCA) have not been completely elucidated. HSulf-1 predominantly functions by limiting the bioavailability of heparan binding growth factors and hence their downstream signaling. Here we report that HSulf-1, a known putative tumor suppressor, is a negative regulator of glycolysis. Silencing of HSulf-1 expression in OV202 cell line increased glucose uptake and lactate production by upregulating glycolytic genes such as Glut1, HKII, LDHA, as well as metabolites. Conversely, HSulf-1 overexpression in TOV21G cells resulted in the down regulation of glycolytic enzymes and reduced glycolytic phenotype, supporting the role of HSulf-1 loss in enhanced aerobic glycolysis. HSulf-1 deficiency mediated glycolytic enhancement also resulted in increased inhibitory phosphorylation of pyruvate dehydrogenase (PDH) thus blocking the entry of glucose flux into TCA cycle. Consistent with this, metabolomic and isotope tracer analysis showed reduced glucose flux into TCA cycle. Moreover, HSulf-1 loss is associated with lower oxygen consumption rate (OCR) and impaired mitochondrial function. Mechanistically, lack of HSulf-1 promotes c-Myc induction through HB-EGF-mediated p-ERK activation. Pharmacological inhibition of c-Myc reduced HB-EGF induced glycolytic enzymes implicating a major role of c-Myc in loss of HSulf-1 mediated altered glycolytic pathway in OVCA. Similarly, PG545 treatment, an agent that binds to heparan binding growth factors and sequesters growth factors away from their ligand also blocked HB-EGF signaling and reduced glucose uptake in vivo in HSulf-1 deficient cells

Genomic deletion of malic enzyme 2 confers collateral lethality in pancreatic cancer

The genome of pancreatic ductal adenocarcinoma (PDAC) frequently contains deletions of tumour suppressor gene loci, most notably SMAD4, which is homozygously deleted in nearly one-third of cases. As loss of neighbouring housekeeping genes can confer collateral lethality, we sought to determine whether loss of the metabolic gene malic enzyme 2 (ME2) in the SMAD4 locus would create cancer-specific metabolic vulnerability upon targeting of its paralogous isoform ME3. The mitochondrial malic enzymes (ME2 and ME3) are oxidative decarboxylases that catalyse the conversion of malate to pyruvate and are essential for NADPH regeneration and reactive oxygen species homeostasis. Here we show that ME3 depletion selectively kills ME2-null PDAC cells in a manner consistent with an essential function for ME3 in ME2-null cancer cells. Mechanistically, integrated metabolomic and molecular investigation of cells deficient in mitochondrial malic enzymes revealed diminished NADPH production and consequent high levels of reactive oxygen species. These changes activate AMP activated protein kinase (AMPK), which in turn directly suppresses sterol regulatory element-binding protein 1 (SREBP1)-directed transcription of its direct targets including the BCAT2 branched-chain amino acid transaminase 2) gene. BCAT2 catalyses the transfer of the amino group from branched-chain amino acids to α-ketoglutarate (α-KG) thereby regenerating glutamate, which functions in part to support de novo nucleotide synthesis. Thus, mitochondrial malic enzyme deficiency, which results in impaired NADPH production, provides a prime 'collateral lethality' therapeutic strategy for the treatment of a substantial fraction of patients diagnosed with this intractable disease

Reduction of liver fibrosis by rationally designed macromolecular telmisartan prodrugs

At present there are no drugs for the treatment of chronic liver fibrosis that have been approved by the Food and Drug Administration of the United States. Telmisartan, a small-molecule antihypertensive drug, displays antifibrotic activity, but its clinical use is limited because it causes systemic hypotension. Here, we report the scalable and convergent synthesis of macromolecular telmisartan prodrugs optimized for preferential release in diseased liver tissue. We have optimized the release of active telmisartan in fibrotic liver to be depot-like (that is, a constant therapeutic concentration) through the molecular design of telmisartan brush-arm star polymers, and show that these lead to improved efficacy and to the avoidance of dose-limiting hypotension in both metabolically and chemically induced mouse models of hepatic fibrosis, as determined by histopathology, enzyme levels in the liver, intact-tissue protein markers, hepatocyte necrosis protection and gene-expression analyses. In rats and dogs, the prodrugs are retained long term in liver tissue, and have a well-tolerated safety profile. Our findings support the further development of telmisartan prodrugs that enable infrequent dosing in the treatment of liver fibrosis.National Institutes of Health (U.S.) (Grant 1R01CA220468-01)National Institutes of Health (U.S.) (Fellowship 1F32EB023101

Design of BET Inhibitor Prodrugs with Superior Efficacy and Devoid of Systemic Toxicities

Prodrugs engineered for preferential activation in diseased versus normal tissues offer immense potential to improve the therapeutic index of preclinical and clinical-stage active pharmaceutical ingredients that either cannot be developed otherwise or whose efficacy or tolerability it is highly desirable to improve. Such approaches, however, often suffer from trial-and-error design, precluding predictive design and optimization. Here, using BET bromodomain inhibitors (BETi)—a class of epigenetic regulators with proven anti-cancer activity but clinical development hindered by systemic adverse effects–– we introduce a platform that overcomes these challenges. Through tuning of traceless linkers appended to a “brush prodrug” scaffold, we demonstrate that it is possible to correlate in vitro prodrug activation kinetics with in vivo tumor pharmacokinetics, leading to novel BETi prodrugs with enhanced anti-tumor efficacy and devoid of dose-limiting toxicities. This work has immediate clinical implications, introducing principles for the predictive design of prodrugs and potentially overcoming hurdles in drug development. </div