Human pregnancy zone protein stabilizes misfolded proteins including preeclampsia- and Alzheimer's-associated amyloid beta peptide.

Protein misfolding underlies the pathology of a large number of human disorders, many of which are age-related. An exception to this is preeclampsia, a leading cause of pregnancy-associated morbidity and mortality in which misfolded proteins accumulate in body fluids and the placenta. We demonstrate that pregnancy zone protein (PZP), which is dramatically elevated in maternal plasma during pregnancy, efficiently inhibits in vitro the aggregation of misfolded proteins, including the amyloid beta peptide (Aβ) that is implicated in preeclampsia as well as with Alzheimer's disease. The mechanism by which this inhibition occurs involves the formation of stable complexes between PZP and monomeric Aβ or small soluble Aβ oligomers formed early in the aggregation pathway. The chaperone activity of PZP is more efficient than that of the closely related protein alpha-2-macroglobulin (α2M), although the chaperone activity of α2M is enhanced by inducing its dissociation into PZP-like dimers. By immunohistochemistry analysis, PZP is found primarily in extravillous trophoblasts in the placenta. In severe preeclampsia, PZP-positive extravillous trophoblasts are adjacent to extracellular plaques containing Aβ, but PZP is not abundant within extracellular plaques. Our data support the conclusion that the up-regulation of PZP during pregnancy represents a major maternal adaptation that helps to maintain extracellular proteostasis during gestation in humans. We propose that overwhelming or disrupting the chaperone function of PZP could underlie the accumulation of misfolded proteins in vivo. Attempts to characterize extracellular proteostasis in pregnancy will potentially have broad-reaching significance for understanding disease-related protein misfolding.Wellcome Trust Programme Grant 094425/Z/10/

Inositol polyphosphate 4-phosphatase II (INPP4B) promotes P13K signalling and functions as an oncogenic regulator in human colon cancer and melanoma

Research Doctorate - Doctor of Philosophy (PhD)Aberrant activation of survival-signaling pathways causes uncontrolled cell proliferation and resistance to apoptosis, and plays an important role in cancer development, progression, and resistance to treatment (Courtney et al., 2010; Ferte et al., 2010). In colorectal cancer (CRC), activation of the phosphatidylinositol 3-kinase (PI3K) pathway is of particular importance, in that many common genetic and epigenetic anomalies in the disease, such as amplification of epidermal growth factor (EGF) receptor, activating mutations in KRAS, and loss of phosphate and tensin homolog deleted on chromosome 10 (PTEN), converge on activation of PI3K signalling (Colakoglu et al., 2008). Moreover, activating mutations of PIK3CA, the gene encoding the catalytic subunit of PI3K, is found in up to 40% of colon cancers (Colakoglu et al., 2008; De Roock et al., 2011). In melanoma, identification of activating mutations in BRAF as the major cause of constitutive activation of the mitogen activated protein kinase (MAPK) pathway has led to successful development of mutant BRAF-specific inhibitors in the treatment of the disease (Chapman et al., 2011; Davies et al., 2002; Houslay, 2011; Ribas and Flaherty, 2011). However, primary and acquired resistance, which is commonly associated with activation of other survival pathways, in particular, the phosphatidylinositol 3-kinase (PI3K) signaling pathway, remains a major obstacle in the quest for curative treatment (Jiang et al., 2011; Karreth et al., 2011; Paraiso et al., 2011; Poulikakos and Rosen, 2011). Indeed, activation of PI3K signaling has been shown to cooperate with mutant BRAF in melanomagenesis using in vivo models (Cheung et al., 2008; Dankort et al., 2009). Activation of PI3K signaling is negatively regulated by three classes of inositol polyphosphate phosphatases (Fedele et al., 2010; Gewinner et al., 2009; Kisseleva et al., 2002). The inositol polyphosphate 3-phosphatase (3-phosphatase) PTEN dephosphorylates the 3-position of PI(3,4,5)P₃ to generate PI(4,5)P₂ (Carracedo et al., 2011; Ma et al., 2008), whereas 5-phosphatases, such as Src homology 2-containing inositol 5- phosphatase (SHIP) and phosphatidylinositol 4,5-Bisphosphate 5- Phosphatase (PIB5PA)/proline-rich inositol polyphosphate phosphatase (PIPP) dephosphorylate the 5-position to produce PI(3,4)P₂ (Ooms et al., 2006; Ye et al., 2013a). PI(3,4)P₂ is in turn subjected to dephosphorylation by inositol polyphosphate 4-phosphatase type I (INPP4A) and type II (INPP4B) at the 4-position to generate PI(3)P, thus terminating PI3K signaling (Fedele et al., 2010; Gewinner et al., 2009; Hodgson et al., 2011). Interestingly, despite INPP4B tumor suppressive role in some other tissues, in this study we found that inositol polyphosphate 4-phosphatase type II (INPP4B) functions as an oncogenic regulator in human colon cancer and melanoma. While INPP4B is upregulated in two cancers and its high expression is associated with poor patient survival, INPP4B knockdown blocks activation of PI3K downstream signaling, inhibits proliferation, undermines survival of colon cancer and melanoma cells, and retards cancer growth in a xenograft model. Conversely, overexpression of INPP4B causes increased proliferation and anchorage-independent growth in normal colon epithelial cells and melanocytes. However, INPP4B regulates PI3K signalling pathway in two cancers by different mechanisms. It plays an important role for maintaining cellular PI(3,4,5)P₃ and PI(3,4)P₂ levels in colon cancer whereas PI(3)P levels in melanoma cells. Also, the increase in INPP4B is primarily due to Ets-1-mediated transcriptional upregulation in colon cancer cells, whereas a posttranscriptional increase via reduction of miRNA-494 and miRNA-599 in melanoma

Insulin induces drug resistance in melanoma through activation of the PI3K/Akt pathway

Introduction: There is currently no curative treatment for melanoma once the disease spreads beyond the original site. Although activation of the PI3K/Akt pathway resulting from genetic mutations and epigenetic deregulation of its major regulators is known to cause resistance of melanoma to therapeutic agents, including the conventional chemotherapeutic drug dacarbazine and the Food and Drug Administration-approved mutant BRAF inhibitors vemurafenib and dabrafenib, the role of extracellular stimuli of the pathway, such as insulin, in drug resistance of melanoma remains less understood. Objective: To investigate the effect of insulin on the response of melanoma cells to dacarbazine, and in particular, the effect of insulin on the response of melanoma cells carrying the BRAFV600E mutation to mutant BRAF inhibitors. An additional aim was to define the role of the PI3K/Akt pathway in the insulin-triggered drug resistance. Methods: The effect of insulin on cytotoxicity induced by dacarbazine or the mutant BRAF inhibitor PLX4720 was tested by pre-incubation of melanoma cells with insulin. Cytotoxicity was determined by the MTS assay. The role of the PI3K/Akt pathway in the insulin-triggered drug resistance was examined using the PI3K inhibitor LY294002 and the PI3K and mammalian target of rapamycin dual inhibitor BEZ-235. Activation of the PI3K/Akt pathway was monitored by Western blot analysis of phosphorylated levels of Akt. Results: Recombinant insulin attenuated dacarbazine-induced cytotoxicity in both wild-type BRAF and BRAFV600E melanoma cells, whereas it also reduced killing of BRAFV600E melanoma cells by PLX4720. Nevertheless, the protective effect of insulin was abolished by the PI3K and mTOR dual inhibitor BEZ-235 or the PI3K inhibitor LY294002. Conclusion: Insulin attenuates the therapeutic efficacy of dacarbazine and PLX4720 in melanoma cells, which is mediated by activation of the PI3K/Akt pathway and can be overcome by PI3K inhibitors

Can Hemp Help? Low-THC Cannabis and Non-THC Cannabinoids for the Treatment of Cancer

Cannabis has been used to relieve the symptoms of disease for thousands of years. However, social and political biases have limited effective interrogation of the potential benefits of cannabis and polarised public opinion. Further, the medicinal and clinical utility of cannabis is limited by the psychotropic side effects of ∆9-tetrahydrocannabinol (∆9-THC). Evidence is emerging for the therapeutic benefits of cannabis in the treatment of neurological and neurodegenerative diseases, with potential efficacy as an analgesic and antiemetic for the management of cancer-related pain and treatment-related nausea and vomiting, respectively. An increasing number of preclinical studies have established that ∆9-THC can inhibit the growth and proliferation of cancerous cells through the modulation of cannabinoid receptors (CB1R and CB2R), but clinical confirmation remains lacking. In parallel, the anti-cancer properties of non-THC cannabinoids, such as cannabidiol (CBD), are linked to the modulation of non-CB1R/CB2R G-protein-coupled receptors, neurotransmitter receptors, and ligand-regulated transcription factors, which together modulate oncogenic signalling and redox homeostasis. Additional evidence has also demonstrated the anti-inflammatory properties of cannabinoids, and this may prove relevant in the context of peritumoural oedema and the tumour immune microenvironment. This review aims to document the emerging mechanisms of anti-cancer actions of non-THC cannabinoids

Human pregnancy zone protein stabilizes misfolded proteins including preeclampsia- and Alzheimer\u27s- associated amyloid beta peptide

Protein misfolding underlies the pathology of a large number of human disorders, many of which are age-related. An exception to this is preeclampsia, a leading cause of pregnancy-associated morbidity and mortality in which misfolded proteins accumulate in body fluids and the placenta. We demonstrate that pregnancy zone protein (PZP), which is dramatically elevated in maternal plasma during pregnancy, efficiently inhibits in vitro the aggregation of misfolded proteins, including the amyloid beta peptide (Aβ) that is implicated in preeclampsia as well as with Alzheimer\u27s disease. The mechanism by which this inhibition occurs involves the formation of stable complexes between PZP and monomeric Aβ or small soluble Aβ oligomers formed early in the aggregation pathway. The chaperone activity of PZP is more efficient than that of the closely related protein alpha-2-macroglobulin (α2M), although the chaperone activity of α2M is enhanced by inducing its dissociation into PZP-like dimers. By immunohistochemistry analysis, PZP is found primarily in extravillous trophoblasts in the placenta. In severe preeclampsia, PZP-positive extravillous trophoblasts are adjacent to extracellular plaques containing Aβ, but PZP is not abundant within extracellular plaques. Our data support the conclusion that the up-regulation of PZP during pregnancy represents a major maternal adaptation that helps to maintain extracellular proteostasis during gestation in humans. We propose that overwhelming or disrupting the chaperone function of PZP could underlie the accumulation of misfolded proteins in vivo. Attempts to characterize extracellular proteostasis in pregnancy will potentially have broad-reaching significance for understanding disease-related protein misfolding