Abstract P5-07-09: Stem cell-like transcriptional reprogramming in metastatic resistance

Whether an aggressive phenotype is promoted through adaptation or resistance to target inhibition remains poorly understood. Here, complementary studies in human tumors, xenograft models and cell lines reveal transcriptional reprogramming that supports metastasis in response to PI3K/mTOR inhibition. This feature is driven by stem cell-like transcription factors. These factors functionally cooperate to promote transcriptional up-regulation of key mTOR pathway components and of metastasis mediators. Their expression is also associated with stem cell-like and metastasis signatures in tumors, and their depletion impairs the metastatic potential of breast cancer cells.Whether an aggressive phenotype is promoted through adaptation or resistance to target inhibition remains poorly understood. Here, complementary studies in human tumors, xenograft models and cell lines reveal transcriptional reprogramming that supports metastasis in response to PI3K/mTOR inhibition. This feature is driven by stem cell-like transcription factors. These factors functionally cooperate to promote transcriptional up-regulation of key mTOR pathway components and of metastasis mediators. Their expression is also associated with stem cell-like and metastasis signatures in tumors, and their depletion impairs the metastatic potential of breast cancer cells.

Citation Format: Pujana MA, Mateo F, Arenas EJ, Gomis R. Stem cell-like transcriptional reprogramming in metastatic resistance [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-07-09.

Stem cell-like transcriptional reprogramming mediates metastatic resistance to mTOR inhibition

Inhibitors of the mechanistic target of rapamycin (mTOR) are currently used to treat advanced metastatic breast cancer. However, whether an aggressive phenotype is sustained through adaptation or resistance to mTOR inhibition remains unknown. Here, complementary studies in human tumors, cancer models and cell lines reveal transcriptional reprogramming that supports metastasis in response to mTOR inhibition. This cancer feature is driven by EVI1 and SOX9. EVI1 functionally cooperates with and positively regulates SOX9, and promotes the transcriptional upregulation of key mTOR pathway components (REHB and RAPTOR) and of lung metastasis mediators (FSCN1 and SPARC). The expression of EVI1 and SOX9 is associated with stem cell-like and metastasis signatures, and their depletion impairs the metastatic potential of breast cancer cells. These results establish the mechanistic link between resistance to mTOR inhibition and cancer metastatic potential, thus enhancing our understanding of mTOR targeting failure.

Degradation of cyclin A is regulated by acetylation

Cyclin A accumulates at the onset of S phase, remains high during G(2) and early mitosis and is degraded at prometaphase. Here, we report that the acetyltransferase P/CAF directly interacts with cyclin A that as a consequence becomes acetylated at lysines 54, 68, 95 and 112. Maximal acetylation occurs simultaneously to ubiquitylation at mitosis, indicating importance of acetylation on cyclin A stability. This was further confirmed by the observation that the pseudoacetylated cyclin A mutant can be ubiquitylated whereas the nonacetylatable mutant cannot. The nonacetylatable mutant is more stable than cyclin A WT (cycA WT) and arrests cell cycle at mitosis. Moreover, in cells treated with histone deacetylase inhibitors cyclin A acetylation increases and its stability decreases, thus supporting the function of acetylation on cyclin A degradation. Although the nonacetylatable mutant cannot be ubiquitylated, it interacts with the proteins needed for its degradation (cdks, Cks, Cdc20, Cdh1 and APC/C). In fact, its association with cdks is increased and its complexes with these kinases display higher activity than control cycA WT-cdk complexes. All these results indicate that cyclin A acetylation at specific lysines is crucial for cyclin A stability and also has a function in the regulation of cycA-cdk activity.

Neural network models for prediction of trichothecene content in wheat

Fusarium graminearum is a mould that causes serious diseases in cereals worldwide and that synthesises mycotoxins such as deoxynivalenol (DON), which can seriously affect human and animal health. Predicting the level of mycotoxin accumulation in food is very difficult, because of the complexity of the influencing parameters. In this work, we have studied the possibility of using artificial neural networks (NN) to predict DON level attained in F. graminearum wheat cultures taking as inputs the fungal contamination level of the cereal, the water activity as a measure of the available water for fungal growth in the cereal, the temperature and time. DON analysis was performed by gas chromatography with electron capture detection. The data matrix was used to train and validate various types of NN using MATLAB 7.0. The aim was to obtain a network that provided the best possible fit between predicted and target DON levels by minimising the mean-square error of test. Radial basis function-NNs attained lower errors and better generalisation than multi-layer perceptron networks to predict DON accumulation in wheat. This is the first time that NNs have been used to predict DON accumulation in wheat based on the studied factors.

Effects of high-dose ipratropium bromide and oral aminophylline on spirometry and exercise tolerance in COPD

Exercise tolerance in chronic obstructive pulmonary disease (COPD) patients treated with oral aminophylline may be different from those treated with high-dose inhaled ipratropium bromide. The purpose of this study was to compare the effects of therapeutic doses of oral aminophylline with high-dose ipratropium bromide on spirometry and exercise tolerance. The study was conducted on three consecutive days in a double-blind, randomized, crossover fashion. Baseline studies obtained on each study day included vital signs, simple spirometry and a symptom-limited maximal cardiopulmonary stress test, after which patients received one of the following treatments on each day: Treatment 1, inhaled ipratropium (total dose of 144 micrograms) with placebo tablets; Treatment 2, inhaled placebo with oral aminophylline (400 mg); Treatment 3, inhaled placebo and placebo tablets. Simple spirometry was repeated at 60 and 120 min after baseline. Vital signs and cardiopulmonary stress testing was repeated at 120 min. Eighteen patients were enrolled in the study, and 17 of these completed the study. There was a significant (P < 0.05) increase in both forced expiratory volume in 1 s (FEV1), from 0.75 (0.21) to 0.92 (0.3), and forced vital capacity (FVC), from 1.8 (0.79) to 2.11 (0.84), with high-dose ipratropium despite prior beta-agonist therapy. Lack of improvement in exercise capacity was noted with ipratropium despite improvement in spirometry. These results suggest that elderly patients with severe COPD may have exercise limitation that is not directly dependent on severity of airflow obstruction. Ipratropium bromide and aminophylline demonstrated no acute effects on exercise capacity.

Transient exacerbation of tuberculous lymphadenitis during chemotherapy in patients with AIDS

We describe three men with disseminated, drug-sensitive tuberculosis and advanced human immunodeficiency virus disease (CD4+ lymphocyte count, < 50/mm3) who had flares of tuberculous lymphadenitis with suppuration during the initial weeks of successful chemotherapy. Bactericidal drugs may kindle these transient exacerbations, which involve neutrophils but apparently do not require normal helper T cell function. In patients with AIDS, as in immunocompetent individuals, treatment-related flares of lymphadenitis are usually not an adverse sign, provided that drug resistance and nonadherence have been excluded.

Control analysis of rat liver glycolysis under different glucose concentrations. The substrate approach and the role of glucokinase

Control Analysis has been carried out in the first steps of a rat liver glycolytic system. Attention has been focused on the effect of several glucose concentrations on the control, particularly regarding the role of glucokinase. From kinetic studies of the whole metabolic system we have obtained information on the flux variation under different glucose concentrations. This information together with the kinetics of glucokinase has allowed us to calculate Flux Control and Elasticity Coefficients for glucokinase and the Response Coefficient of the system with respect to glucose. The changes in of the value of Flux Control Coefficients demonstrates that in conditions of low glucose concentration, glucokinase is the main enzyme in controlling the flux through the pathway, but at high glucose concentration the control moves to phosphofructokinase. Next, we have compared our results with those obtained with the shortening and titration method, previously described (Torres, N.V., Mateo, F., Meléndez-Hevia, E. and Kacser, H., (1986) Biochem. J. 234, 169-174; Torres, N.V. and Meléndez-Hevia, E. 1991. Molec. Cell. Biochem. 101, 1-10). Furthermore, from knowledge of the enzyme kinetics of the system we have been able to build a model of the pathway that allows us computer similation of its behavior and calculation of the Flux Control Coefficient profile at different glucose concentrations. By the three methods the results correlate, supporting the use of the pathway substrate as external modulator of the metabolic system as a tool for practical application of Control Analysis.

Bronchial metastases from ovarian carcinoma. Report of a case and review of the literature

A patient with ovarian cystadenocarcinoma developed respiratory insufficiency due to bilateral endobronchial metastases, 6.5 years after treatment of the primary tumor. Ovarian cancers frequently metastasize to the pleura and lung parenchyma. Clinically significant bronchial metastases are rare. Only three cases have been reported previously. As in our patient, bronchial metastases tend to occur after a relatively long interval from diagnosis of the primary tumor, and survival may be prolonged after their appearance.

Control of glycolysis in rat liver by glucokinase and phosphofructokinase: influence of glucose concentration

Control of glucose metabolism in rat liver under different glucose concentrations was studied. Flux Control Coefficients of glucokinase, glucose 6-phosphate isomerase and phosphofructokinase were determined by the 'shortening and enzyme titration' method. Results obtained show that glucose concentration in liver can play an important role in control of liver glycolysis by enhancing the Flux Control Coefficient of phosphofructokinase. Possible physiological significance of this fact is discussed.

Shift in rat liver glycolysis control from fed to starved conditions. Flux control coefficients of glucokinase and phosphofructokinase

The distribution of flux control coefficients of a glycolytic system in starved rat liver has been determined. The flux control coefficient profile in starved conditions is compared with normal fed conditions showing that in the former phosphofructokinase enhances more than 2-fold its flux control coefficient while glucokinase decreases slightly. The results also show that the starved system has a more complex structure probably because of the greater influence on the flux of the reverse substrate cycles and the synthesis and degradation fructose 2,6-bisphosphate reactions.

Distribution of the flux control in convergent metabolic pathways: theory and application to experimental and simulated systems

1. Metabolic systems involving branched convergent pathways are analyzed under Flux Control Theory, obtaining a relationship between the contribution of every convergent pathway to the total flux and its Flux Control Coefficient. 2. An experimental model system is carried out to demonstrate the physical application of some conclusions of theoretical treatment. 3. Two different types of branched pathways are simulated by computer. 4. In both cases results are in agreement with the theoretical conclusions, showing in addition some new aspects on metabolic control.

Kinetics of metabolic pathways. A system in vitro to study the control of flux

A method for determining Control Coefficients is proposed for systems studied in vitro and applied to a model pathway. Rat liver extract, which converts glucose into glycerol 3-phosphate, was used with the addition to the incubation mixture of fructose-bisphosphate aldolase, triose-phosphate isomerase and glycerol-3-phosphate dehydrogenase as 'auxiliary' enzymes, which leaves all the control on the first three enzymes. The flux of the metabolic pathway was recorded by assaying NADH decay. Flux Control Coefficients (CJE) of hexokinase, glucose-6-phosphate isomerase and phosphofructokinase were calculated by titration of the system with increasing quantities of extraneous enzymes. It is shown that the summation property is fulfilled. The applicability of this procedure to study the control in any metabolic pathway is discussed. Possible relevance of the method to conditions in vivo and its limitations are considered.