Inositol pyrophosphates modulate cell cycle independently of alteration in telomere length

Synthesis of inositol pyrophosphates through activation of Kcs1 plays an important role in the signalling response required for cell cycle progression after mating pheromone arrest. Overexpression of Kcs1 doubled the level of inositol pyrophosphates when compared to wild type cells and 30 min following the release from α-factor block further increase in inositol pyrophosphates was observed, which resulted that cells overexpressing Kcs1 reached G2/M phase earlier than wild type cells. Similar effect was observed in ipk1Δ cells, which are unable to synthesize IP6-derived inositol pyrophosphates (IP7 and IP8) but will synthesize IP5-derived inositol pyrophosphates (PP-IP4 and (PP)2-IP3). Although ipk1Δ cells have shorter telomeres than wild type cells, overexpression of Kcs1 in both strains have similar effect on cell cycle progression. As it is known that PP-IP4 regulates telomere length through Tel1, inositol polyphosphates, cell cycle and telomere length were determined in tel1Δ cells. The release of the cells from α-factor block and overexpression of Kcs1 in tel1Δ cells produced similar effects on inositol pyrophosphates level and cell cycle progression when compared to wild type cells, although tel1Δ cells possesses shorter telomeres than wild type cells. It can be concluded that telomere length does not affect cell cycle progression, since cells with short telomeres (ipk1Δ and tel1Δ) progress through cell cycle in a similar manner as wild type cells and that overexpression of Kcs1 in cells with either short or normal telomeres will increase S phase progression without affecting telomere length. Furthermore, IP5-derived inositol pyrophosphates can compensate for the loss of IP6-derived inositol pyrophosphates, in modulating S phase progression of the cell cycle

The impact of whole human blood on the kinetic inertness of platinum(IV) prodrugs - an HPLC-ICP-MS study

The potential advantage of platinum(IV) complexes as alternative to classical platinum(II)-based drugs relies on their kinetic stability in the body before reaching the tumor site and on their activation by reduction inside cancer cells. In this study, an analytical workflow was developed to investigate the reductive biotransformation and kinetic inertness of platinum(IV) prodrugs comprising different ligand coordination spheres (respectively, lipophilicity and redox behavior) in whole human blood. The distribution of the platinum(IV) complexes in blood pellet and plasma was determined by inductively coupled plasma-mass spectrometry (ICP-MS) after microwave digestion. An analytical approach based on reversed-phase (RP)-ICP-MS was used to monitor the parent compound and the formation of metabolites using two different extraction procedures. The ligand coordination sphere of the platinum(IV) complexes had significant impact on their accumulation in red blood cells and on their degree of kinetic inertness in whole human blood. The most lipophilic platinum(IV) compound featuring equatorial chlorido ligands showed a pronounced penetration into blood cells and a rapid reductive biotransformation. In contrast, the more hydrophilic platinum(IV) complexes with a carboplatin- and oxaliplatin-core exerted kinetic inertness on a pharmacologically relevant time scale with notable amounts of the compound accumulated in the plasma fraction

Differential responses to doxorubicin-induced phosphorylation and activation of Akt in human breast cancer cells

INTRODUCTION: We have shown previously that overexpression of constitutively active Akt or activation of Akt caused by constitutively active Ras or human epidermal growth factor receptor-2 (HER2) confers on breast cancer cells resistance to chemotherapy or radiotherapy. As an expanded study we here report differential responses in terms of phosphorylation and activation of Akt as a result of treatment with doxorubicin in a panel of breast cancer cell lines. METHODS: The levels of Akt phosphorylation and activity were measured by Western blot analysis with an anti-Ser473-phosphorylated Akt antibody and by in vitro Akt kinase assay using glycogen synthase kinase-3 as a substrate. RESULTS: Within 24 hours after exposure to doxorubicin, MCF7, MDA468 and T47D cells showed a drug-dose-dependent increase in the levels of phosphorylated Akt; in contrast, SKBR3 and MDA231 cells showed a decrease in the levels of phosphorylated Akt, and minimal or no changes were detected in MDA361, MDA157 and BT474 cells. The doxorubicin-induced Akt phosphorylation was correlated with increased kinase activity and was dependent on phosphoinositide 3-kinase (PI3-K). An increased baseline level of Akt was also found in MCF7 cells treated with ionizing radiation. The cellular responses to doxorubicin-induced Akt phosphorylation were potentiated after the expression of Akt upstream activators including HER2, HER3 and focal adhesion kinase. CONCLUSION: Taken together with our recent published results showing that constitutive Akt mediates resistance to chemotherapy or radiotherapy, our present data suggest that the doxorubicin-induced phosphorylation and activation of Akt might reflect a cellular defensive mechanism of cancer cells to overcome doxorubicin-induced cytotoxic effects, which further supports the current efforts of targeting PI3-K/Akt for enhancing the therapeutic responses of breast cancer cells to chemotherapy and radiotherapy

Guidance for the Management of Patients with Vascular Disease or Cardiovascular Risk Factors and COVID-19: Position Paper from VAS-European Independent Foundation in Angiology/Vascular Medicine .

COVID-19 is also manifested with hypercoagulability, pulmonary intravascular coagulation, microangiopathy, and venous thromboembolism (VTE) or arterial thrombosis. Predisposing risk factors to severe COVID-19 are male sex, underlying cardiovascular disease, or cardiovascular risk factors including noncontrolled diabetes mellitus or arterial hypertension, obesity, and advanced age. The VAS-European Independent Foundation in Angiology/Vascular Medicine draws attention to patients with vascular disease (VD) and presents an integral strategy for the management of patients with VD or cardiovascular risk factors (VD-CVR) and COVID-19. VAS recommends (1) a COVID-19-oriented primary health care network for patients with VD-CVR for identification of patients with VD-CVR in the community and patients' education for disease symptoms, use of eHealth technology, adherence to the antithrombotic and vascular regulating treatments, and (2) close medical follow-up for efficacious control of VD progression and prompt application of physical and social distancing measures in case of new epidemic waves. For patients with VD-CVR who receive home treatment for COVID-19, VAS recommends assessment for (1) disease worsening risk and prioritized hospitalization of those at high risk and (2) VTE risk assessment and thromboprophylaxis with rivaroxaban, betrixaban, or low-molecular-weight heparin (LMWH) for those at high risk. For hospitalized patients with VD-CVR and COVID-19, VAS recommends (1) routine thromboprophylaxis with weight-adjusted intermediate doses of LMWH (unless contraindication); (2) LMWH as the drug of choice over unfractionated heparin or direct oral anticoagulants for the treatment of VTE or hypercoagulability; (3) careful evaluation of the risk for disease worsening and prompt application of targeted antiviral or convalescence treatments; (4) monitoring of D-dimer for optimization of the antithrombotic treatment; and (5) evaluation of the risk of VTE before hospital discharge using the IMPROVE-D-dimer score and prolonged post-discharge thromboprophylaxis with rivaroxaban, betrixaban, or LMWH

Role of ERK and JNK pathways in regulating cell motility and matrix metalloproteinase 9 production in growth factor-stimulated human epidermal keratinocytes

Invasion is an essential cellular response that plays an important role in a number of physiological and pathological processes. Matrix metalloproteinase (MMP) production and cell movement are diverse cellular responses integral to the process of invasion. The complexity of the invasive process suggests the necessity of coordinate activation of more than one signaling pathway in order to activate specific factors responsible for regulating these cellular responses. In this report, we demonstrate that cell movement and MMP-9 production are both directly dependent on the activation of endogenous ERK signaling in hepatocyte growth factor (HGF)-or epidermal growth factor (EGF)-stimulated human epidermal keratinocytes. The kinetic profiles of endogenous MEK and ERK activity suggest that prolonged activation of these signal transducers is an underlying mechanism involved in stimulating cell motility and MMP-9 production. In support of this finding, a transient MEK/ERK signal elicited by keratinocyte growth factor (KGF) or insulin-like growth factor-1 (IGF-1) fails to stimulate these invasion-related responses. Specific inhibition of MEK leads to suppression of ERK activation, marked reduction in steady-state levels of c-Fos, and inhibition of cell movement and MMP-9 production. This occurs despite continued activation of JNK and c-Jun signaling in the presence of MEK-specific inhibition. In contrast, when JNK activity is specifically inhibited in HGF-stimulated cells, AP-1 activity is suppressed but cell motility is not affected. This evidence suggests that while ERK and JNK activity are necessary for AP-1 activation, ERK but not JNK is sufficient in stimulating cell motility. J. Cell. Physiol. 180:271–284, 1999. © 1999 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34441/1/15_ftp.pd