Glucose metabolism and hexosamine pathway regulate oncogene-induced senescence

A Corrigendum to this article was published on 14 August 2014 6 DOI / 10.1038/cddis.2014.360Since the publication of this paper the authors have noticed an error in the abstract section. ‘Inversely, expressing a G6P,pharmacological inhibition of HK2,’ is replaced by ‘Inversely, expressing a glucose-6-phosphatase, pharmacological inhibition of HK2,’.The corrected article appears online together with this corrigendum.The authors would like to apologize for any inconvenience caused.International audienceOncogenic stress-induced senescence (OIS) prevents the ability of oncogenic signals to induce tumorigenesis. It is now largely admitted that the mitogenic effect of oncogenes requires metabolic adaptations to respond to new energetic and bio constituent needs. Yet, whether glucose metabolism affects OIS response is largely unknown. This is largely because of the fact that most of the OIS cellular models are cultivated in glucose excess. In this study, we used human epithelial cells, cultivated without glucose excess, to study alteration and functional role of glucose metabolism during OIS. We report a slowdown of glucose uptake and metabolism during OIS. Increasing glucose metabolism by expressing hexokinase2 (HK2), which converts glucose to glucose-6phosphate (G6P), favors escape from OIS. Inversely, expressing a glucose-6-phosphatase, pharmacological inhibition of HK2, or adding nonmetabolizable glucose induced a premature senescence. Manipulations of various metabolites covering G6P downstream pathways (hexosamine, glycolysis, and pentose phosphate pathways) suggest an unexpected role of the hexosamine pathway in controlling OIS. Altogether, our results show that decreased glucose metabolism occurs during and participates to OIS

Lysyl oxidase activity regulates oncogenic stress response and tumorigenesis

International audienceCellular senescence, a stable proliferation arrest, is induced in response to various stresses. Oncogenic stress-induced senescence (OIS) results in blocked proliferation and constitutes a fail-safe program counteracting tumorigenesis. The events that enable a tumor in a benign senescent state to escape from OIS and become malignant are largely unknown. We show that lysyl oxidase activity contributes to the decision to maintain senescence. Indeed, in human epithelial cell the constitutive expression of the LOX or LOXL2 protein favored OIS escape, whereas inhibition of lysyl oxidase activity was found to stabilize OIS. The relevance of these in vitro observations is supported by in vivo findings: in a transgenic mouse model of aggressive pancreatic ductal adenocarcinoma (PDAC), increasing lysyl oxidase activity accelerates senescence escape, whereas inhibition of lysyl oxidase activity was found to stabilize senescence, delay tumorigenesis, and increase survival. Mechanistically, we show that lysyl oxidase activity favors the escape of senescence by regulating the focal-adhesion kinase. Altogether, our results demonstrate that lysyl oxidase activity participates in primary tumor growth by directly impacting the senescence stability

Intermediate-conductance Ca2+-activated K+ channels (IKCa1) regulate human prostate cancer cell proliferation through a close control of calcium entry

International audienceAccumulating data point to K þ channels as relevant players in controlling cell cycle progression and proliferation of human cancer cells, including prostate cancer (PCa) cells. However, the mechanism(s) by which K þ channels control PCa cell proliferation remain illusive. In this study, using the techniques of molecular biology, biochemistry, electrophysiology and calcium imaging, we studied the expression and functionality of intermediate-conductance calcium-activated potassium channels (IK Ca1) in human PCa as well as their involvement in cell proliferation. We showed that IK Ca1 mRNA and protein were preferentially expressed in human PCa tissues, and inhibition of the IK Ca1 potassium channel suppressed PCa cell proliferation. The activation of IK Ca1 hyperpolarizes membrane potential and, by promoting the driving force for calcium, induces calcium entry through TRPV6, a cation channel of the TRP (Transient Receptor Potential) family. Thus, the overexpression of the IK Ca1 channel is likely to promote carcinogenesis in human prostate tissue