Ubiquitous presence of gluconeogenic regulatory enzyme, fructose-1,6-bisphosphatase, within layers of rat retina

To shed some light on gluconeogenesis in mammalian retina, we have focused on fructose-1,6-bisphosphatase (FBPase), a regulatory enzyme of the process. The abundance of the enzyme within the layers of the rat retina suggests that, in mammals in contrast to amphibia, gluconeogenesis is not restricted to one specific cell of the retina. We propose that FBPase, in addition to its gluconeogenic role, participates in the protection of the retina against reactive oxygen species. Additionally, the nuclear localization of FBPase and of its binding partner, aldolase, in the retinal cells expressing the proliferation marker Ki-67 indicates that these two gluconeogenic enzymes are involved in non-enzymatic nuclear processes

Effects of the Mutant TP53 Reactivator APR-246 on Therapeutic Sensitivity of Pancreatic Cancer Cells in the Presence and Absence of WT-TP53

The TP53 tumor suppressor is mutated in ~75% of pancreatic cancers. The mutant TP53 protein in pancreatic ductal adenocarcinomas (PDAC) promotes tumor growth and metastasis. Attempts have been made to develop molecules that restore at least some of the properties of wildtype (WT) TP53. APR-246 is one such molecule, and it is referred to as a mutant TP53 reactivator. To understand the potential of APR-246 to sensitize PDAC cells to chemotherapy, we introduced a vector encoding WT-TP53 into two PDAC cell lines, one lacking the expression of TP53 (PANC-28) and one with a gain-of-function (GOF) mutant TP53 (MIA-PaCa-2). APR-246 increased drug sensitivity in the cells containing either a WT or mutant TP53 protein with GOF activity, but not in cells that lacked TP53. The introduction of WT-T53 into PANC-28 cells increased their sensitivity to the TP53 reactivator, chemotherapeutic drugs, and signal transduction inhibitors. The addition of WT-TP53 to PDAC cells with GOF TP53 also increased their sensitivity to the drugs and therapeutics, indicating that APR-246 could function in cells with WT-TP53 and GOF TP53. These results highlight the importance of knowledge of the type of TP53 mutation that is present in cancer patients before the administration of drugs which function through the reactivation of TP53

Targeting GSK3 and Associated Signaling Pathways Involved in Cancer

Glycogen synthase kinase 3 (GSK-3) is a serine/threonine (S/T) protein kinase. Although GSK-3 originally was identified to have functions in regulation of glycogen synthase, it was subsequently determined to have roles in multiple normal biochemical processes as well as various disease conditions. GSK-3 is sometimes referred to as a moonlighting protein due to the multiple substrates and processes which it controls. Frequently, when GSK-3 phosphorylates proteins, they are targeted for degradation. GSK-3 is often considered a component of the PI3K/PTEN/AKT/GSK-3/mTORC1 pathway as GSK-3 is frequently phosphorylated by AKT which regulates its inactivation. AKT is often active in human cancer and hence, GSK-3 is often inactivated. Moreover, GSK-3 also interacts with WNT/\u3b2-catenin signaling and \u3b2-catenin and other proteins in this pathway are targets of GSK-3. GSK-3 can modify NF-\u3baB activity which is often expressed at high levels in cancer cells. Multiple pharmaceutical companies developed small molecule inhibitors to suppress GSK-3 activity. In addition, various natural products will modify GSK-3 activity. This review will focus on the effects of small molecule inhibitors and natural products on GSK-3 activity and provide examples where these compounds were effective in suppressing cancer growth

Roles of GSK-3 and microRNAs on epithelial mesenchymal transition and cancer stem cells

Various signaling pathways exert critical roles in the epithelial to mesenchymal transition (EMT) and cancer stem cells (CSCs). The Wnt/beta-catenin, PI3K/PTEN/ Akt/mTORC, Ras/Raf/MEK/ERK, hedgehog (Hh), Notch and TP53 pathways elicit essential regulatory influences on cancer initiation, EMT and progression. A common kinase involved in all these pathways is moon-lighting kinase glycogen synthase kinase-3 (GSK-3). These pathways are also regulated by micro-RNAs (miRs). TP53 and components of these pathways can regulate the expression of miRs. Targeting members of these pathways may improve cancer therapy in those malignancies that display their abnormal regulation. This review will discuss the interactions of the multi-functional GSK-3 enzyme in the Wnt/beta-catenin, PI3K/PTEN/Akt/mTORC, Ras/Raf/MEK/ERK, Hh, Notch and TP53 pathways. The regulation of these pathways by miRs and their effects on CSC generation, EMT, invasion and metastasis will be discussed

GSK-3 as potential target for therapeutic intervention in cancer

The serine/threonine kinase glycogen synthase kinase-3 (GSK-3) was initially identified and studied in the regulation of glycogen synthesis. GSK-3 functions in a wide range of cellular processes. Aberrant activity of GSK-3 has been implicated in many human pathologies including: bipolar depression, Alzheimer's disease, Parkinson's disease, cancer, non-insulin-dependent diabetes mellitus (NIDDM) and others. In some cases, suppression of GSK-3 activity by phosphorylation by Akt and other kinases has been associated with cancer progression. In these cases, GSK-3 has tumor suppressor functions. In other cases, GSK-3 has been associated with tumor progression by stabilizing components of the beta-catenin complex. In these situations, GSK-3 has oncogenic properties. While many inhibitors to GSK-3 have been developed, their use remains controversial because of the ambiguous role of GSK-3 in cancer development. In this review, we will focus on the diverse roles that GSK-3 plays in various human cancers, in particular in solid tumors. Recently, GSK-3 has also been implicated in the generation of cancer stem cells in various cell types. We will also discuss how this pivotal kinase interacts with multiple signaling pathways such as: PI3K/PTEN/Akt/mTORC1, Ras/Raf/MEK/ERK, Wnt/beta-catenin, Hedgehog, Notch and others

Effects of the MDM-2 inhibitor Nutlin-3a on PDAC cells containing and lacking WT-TP53 on sensitivity to chemotherapy, signal transduction inhibitors and nutraceuticals

Mutations at the TP53 gene are readily detected (approximately 50-75%) in pancreatic ductal adenocarcinoma (PDAC) patients. TP53 was previously thought to be a difficult target as it is often mutated, deleted or inactivated on both chromosomes in certain cancers. In the following study, the effects of restoration of wild-type (WT) TP53 activity on the sensitivities of MIA-PaCa-2 pancreatic cancer cells to the MDM2 inhibitor nutlin-3a in combination with chemotherapy, targeted therapy, as well as, nutraceuticals were examined. Upon introduction of the WT-TP53 gene into MIA-PaCa-2 cells, which contain a TP53 gain of function (GOF) mutation, the sensitivity to the MDM2 inhibitor increased. However, effects of nutlin-3a were also observed in MIA-PaCa-2 cells lacking WT-TP53, as upon co-treatment with nutlin-3a, the sensitivity to certain inhibitors, chemotherapeutic drugs and nutraceuticals increased. Interestingly, co-treatment with nutlin-3a and certain chemotherapeutic drug such as irinotecan and oxaliplatin resulted in antagonistic effects in cells both lacking and containing WT-TP53 activity. These studies indicate the sensitizing abilities that WT-TP53 activity can have in PDAC cells which normally lack WT-TP53, as well as, the effects that the MDM2 inhibitor nutlin-3a can have in both cells containing and lacking WT-TP53 to various therapeutic agents

Abilities of berberine and chemically modified berberines to interact with metformin and inhibit proliferation of pancreatic cancer cells

Pancreatic cancer is devastating cancer worldwide with few if any truly effective therapies. Pancreatic cancer has an increasing incidence and may become the second leading cause of death from cancer. Novel, more effective therapeutic approaches are needed as pancreatic cancer patients usually survive for less than a year after being diagnosed. Control of blood sugar levels by the prescription drug metformin in diseases such as diabetes mellitus has been examined in association with pancreatic cancer. While the clinical trials remain inconclusive, there is hope that certain diets and medications may affect positively the outcomes of patients with pancreatic and other cancers. Other natural compounds may share some of the effects of metformin. One "medicinal" fruit consumed by millions worldwide is berberine (BBR). Metformin and BBR both activate AMP-activated protein kinase (AMPK) which is a key mediator of glucose metabolism. Glucose metabolism has been shown to be very important in cancer and its significance is increasing. In the following studies, we have examined the effects of metformin, BBR and a panel of modified BBRs (NAX compounds) and chemotherapeutic drugs on the growth of four different human pancreatic adenocarcinoma cell lines (PDAC). Interestingly, the effects of metformin could be enhanced by BBR and certain modified BBRs. Upon restoration of WT-TP53 activity in MIA-PaCa-2 cells, an altered sensitivity to the combination of certain NAX compounds and metformin was observed compared to the parental cells which normally lack WT-TP53. Certain NAX compounds may interact with WT-TP53 and metformin treatment to alter the expression of key molecules involved in cell growth. These results suggest a therapeutic approach by combining certain pharmaceutical drugs and nutraceuticals to suppress the growth of cancer cells

Wild Type and Gain of Function Mutant TP53 can Regulate the Sensitivity of Pancreatic Cancer Cells to Chemotherapeutic Drugs, EGFR/Ras/Raf/MEK, and PI3K/mTORC1/GSK-3 Pathway Inhibitors, Nutraceuticals and Alter Metabolic Properties

TP53 is a master regulator of many signaling and apoptotic pathways involved in: aging, cell cycle progression, metastasis, and metabolism. Most pancreatic cancers are classified as pancreatic ductal adenocarcinomas (PDAC). The tumor suppressor gene TP53 is mutated frequently (50-75%) in PDAC. Different types of TP53 mutations have been observed including gain of function (GOF) point mutations and various deletions of the TP53 gene resulting in lack of the protein expression. Most PDACs have point mutations at the KRAS gene which result in constitutive activation of KRas and multiple downstream signaling pathways. It has been difficult to develop specific KRas inhibitors and/or methods that result in recovery of functional TP53 activity. To further elucidate the roles of TP53 in drug-resistance of pancreatic cancer cells, we introduced wild-type (WT) TP53 or a control vector into two different PDAC cell lines. Introduction of WT-TP53 increased the sensitivity of the cells to multiple chemotherapeutic drugs, signal transduction inhibitors, drugs and nutraceuticals and influenced key metabolic properties of the cells. Therefore, TP53 is a key molecule which is critical in drug sensitivity and metabolism of PDAC

Histological and transcriptome-wide level characteristics of fetal myofiber hyperplasia during the second half of gestation in Texel and Ujumqin sheep

<p>Abstract</p> <p>Background</p> <p>Whether myofibers increase with a pulsed-wave mode at particular developmental stages or whether they augment evenly across developmental stages in large mammals is unclear. Additionally, the molecular mechanisms of myostatin in myofiber hyperplasia at the fetal stage in sheep remain unknown. Using the first specialized transcriptome-wide sheep oligo DNA microarray and histological methods, we investigated the gene expression profile and histological characteristics of developing fetal ovine longissimus muscle in Texel sheep (high muscle and low fat), as a myostatin model of natural mutation, and Ujumqin sheep (low muscle and high fat). Fetal skeletal muscles were sampled at 70, 85, 100, 120, and 135 d of gestation.</p> <p>Results</p> <p>Myofiber number increased sharply with a pulsed-wave mode at certain developmental stages but was not augmented evenly across developmental stages in fetal sheep. The surges in myofiber hyperplasia occurred at 85 and 120 d in Texel sheep, whereas a unique proliferative surge appeared at 100 d in Ujumqin sheep. Analysis of the microarray demonstrated that immune and hematological systems' development and function, lipid metabolism, and cell communication were the biological functions that were most differentially expressed between Texel and Ujumqin sheep during muscle development. Pathways associated with myogenesis and the proliferation of myoblasts, such as calcium signaling, chemokine (C-X-C motif) receptor 4 signaling, and vascular endothelial growth factor signaling, were affected significantly at specific fetal stages, which underpinned fetal myofiber hyperplasia and postnatal muscle hypertrophy. Moreover, we identified some differentially expressed genes between the two breeds that could be potential myostatin targets for further investigation.</p> <p>Conclusions</p> <p>Proliferation of myofibers proceeded in a pulsed-wave mode at particular fetal stages in the sheep. The myostatin mutation changed the gene expression pattern in skeletal muscle at a transcriptome-wide level, resulting in variation in myofiber phenotype between Texel and Ujumqin sheep during the second half of gestation. Our findings provide a novel and dynamic description of the effect of myostatin on skeletal muscle development, which contributes to understanding the biology of muscle development in large mammals.</p

Human lung fructose-1,6-bisphosphatase is localized in pneumocytes II

The localization of fructose-1,6-bisphosphatase (Fru-1,6-Pase EC 3.1.3.11) in human alveolar epithelium was determined immunohistochemically using a polyclonal antibody raised against the enzyme purified from human liver. The immunohistochemical analysis revealed that the Fru-1,6-Pase was localized in pneumocytes 11 and was absent in pneumocytes 1. Hypothetically Fru-1,6-Pase participating in glucose-6-phosphate synthesis from noncarbohydrate precursors increases NADPH leve1 which is used for surfactant synthesis and for glutathione redox cycle