Actualización en el tratamiento de la osteoporosis: algoritmo de decisión. Manejo desde una unidad del dolor (2.ª parte) / Update on the treatment of osteoporosis: Decision algorithm. Management from a unit of pain (II)

La heterogeneidad de los pacientes con osteoporosis hace necesaria una aproximación individualizada para conseguir un equilibrio entre los beneficios y limitaciones de los tratamientos disponibles. La indicación de este se realiza en función del riesgo absoluto de fractura por fragilidad. En los pacientes con un bajo riesgo de fractura son suficientes las medidas higiénicas, prevención de caídas y mantener una ingesta adecuada de calcio y vitamina D. En los pacientes con un riesgo moderado se debe individualizar la necesidad de tratamiento farmacológico e iniciar el tratamiento en aquellos con alto riesgo de fractura. Los fármacos más utilizados son los bifosfonatos, inhibidores de la reabsorción ósea, también se utilizan fármacos osteoanabólicos como la hormona teriparatida, y anticuerpos monoclonales como el denosumab. En los pacientes cuyo dolor no se controla de manera satisfactoria se ha de valorar la indicación de tratamientos mínimamente invasivos como bloqueos espinales, vertebroplastia o cifoplastia (AU)

The heterogeneity of patients with osteoporotic vertebral compression necessitates a tailored approach of balancing the benefits and limitations of available treatments. The indication for treatment is made based on the absolute risk of fragility fracture. In patients with a low risk of fracture are sufficient hygienic measures, preventing falls and maintaining an adequate intake of calcium and vitamin D. In patients with a moderate risk should be individualized drug treatment need and initiate treatment in those at high risk of fracture. The most commonly used drugs are bisphosphonates, inhibitors of bone resorption, also used as hormone teriparatide, osteoanabolic drug and monoclonal antibodies such as denosumab. In patients whose pain is not controlled can satisfactorily assessed the indication for minimally invasive treatments like vertebroplasty, kyphoplasty or spinal blocks (AU)

Actualización en el tratamiento de la osteoporosis. Manejo desde una unidad del dolor (1.ª parte) / Update on the treatment of osteoporosis: management from a unit of pain (I)

La osteoporosis (OP) se define como una enfermedad esquelética caracterizada por una resistencia ósea disminuida que predispone a un aumento en el riesgo de fracturas. En Europa se producen 2,7 millones de fracturas por fragilidad, tanto en hombres como mujeres, con un coste directo de 36 billones de euros. Estas fracturas se asocian con un incremento en la morbilidad y mortalidad. El riesgo de fractura osteoporótica viene determinado por la presencia de uno o más factores de riesgo y el descenso de la densidad mineral ósea (DMO) valorado mediante la técnica Dual Energy X-ray absortiometry (DEXA), densitometría. La indicación de tratamiento se realiza en función del riesgo absoluto de fractura por fragilidad. En los pacientes con un bajo riesgo de fractura son suficientes las medidas higiénicas, prevención de caídas y mantener una ingesta adecuada de calcio y vitamina D. En los pacientes con un riesgo moderado se debe individualizar la necesidad de tratamiento farmacológico e iniciar el tratamiento en aquellos con alto riesgo de fractura. Los fármacos más utilizados son los bifosfonatos, inhibidores de la reabsorción ósea, también se utilizan fármacos osteoanabólicos como la hormona teriparatida y anticuerpos monoclonales como el denosumab (AU)

Osteoporosis (OP) is defined as a skeletal disorder characterized by decreased bone strength, which predisposes to an increase in fracture risk. In Europe produced 2.7 million fragility fractures in both men and women with a direct cost of 36 billion euros. These fractures are associated with increased morbidity and mortality. The risk of osteoporotic fracture is determined by the presence of one or more risk factors and decreased bone mineral density (BMD) assessed by Dual Energy technique absortiometry X-ray (DEXA) densitometry. The indication for treatment is made based on the absolute risk of fragility fracture. In patients with a low risk of fracture are sufficient hygienic measures, preventing falls and maintaining an adequate intake of calcium and vitamin D. In patients with a moderate risk should be individualized drug treatment need and initiate treatment in those at high risk of fracture. The most commonly used drugs are bisphosphonates, inhibitors of bone resorption, also used as hormone teriparatide, osteoanabolic drug and monoclonal antibodies such as denosumab (AU)

Lipid raft-mediated Akt signaling as a therapeutic target in mantle cell lymphoma.

Recent evidence shows that lipid raft membrane domains modulate both cell survival and death. Here, we have found that the phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway is present in the lipid rafts of mantle cell lymphoma (MCL) cells, and this location seems to be critical for full activation and MCL cell survival. The antitumor lipids (ATLs) edelfosine and perifosine target rafts, and we found that ATLs exerted in vitro and in vivo antitumor activity against MCL cells by displacing Akt as well as key regulatory kinases p-PDK1 (phosphatidylinositol-dependent protein kinase 1), PI3K and mTOR (mammalian TOR) from lipid rafts. This raft reorganization led to Akt dephosphorylation, while proapoptotic Fas/CD95 death receptor was recruited into rafts. Raft integrity was critical for Ser473 Akt phosphorylation. ATL-induced apoptosis appeared to correlate with the basal Akt phosphorylation status in MCL cell lines and primary cultures, and could be potentiated by the PI3K inhibitor wortmannin, or inhibited by the Akt activator pervanadate. Classical Akt inhibitors induced apoptosis in MCL cells. Microenvironmental stimuli, such as CD40 ligation or stromal cell contact, did not prevent ATL-induced apoptosis in MCL cell lines and patient-derived cells. These results highlight the role of raft-mediated PI3K/Akt signaling in MCL cell survival and chemotherapy, thus becoming a new target for MCL treatment.

Apoptotic mechanisms are involved in the death of Strongyloides venezuelensis after triggering of nitric oxide.

Despite progress in understanding the role of nitric oxide (NO) in the pathogenesis of helminth infections, the role in strongyloidosis is unknown. Firstly, we studied the production of NO in mice infected with Strongyloides venezuelensis as well as in macrophage cultures stimulated with parasite antigens. Somatic larvae 3 (L3) and excretory-secretory female antigens stimulate specific NO production measured by Griess reaction and expression of inducible NO synthase by RT-PCR and quantitative PCR. Moreover, mice infected with S. venezuelensis produce NO in migration stages. Secondly, we analysed the effect of NO production on L3 and females of S. venezuelensis using NO donors such as diethylenetriamine and 3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene. Parasites died after NO donor treatment in a dose-dependent manner. Finally, apoptotic mechanisms are involved in the death of S. venezuelensis larvae.

Relación entre la actividad arginasa y el tiempo de conservación de los concentrados de hematíes / Relationship between arginase activity and the storage time of packed red blood cells

Objetivos. Dada la creciente evidencia a favor de una relación entre el tiempo de conservación de los concentrados de hematíes y las complicaciones postransfusionales, nos planteamos analizar la relación existente entre los niveles de enzima arginasa, parámetros bioquímicos y de hemólisis, con el tiempo de conservación de concentrados de hematíes transfundidos. Material y métodos. Diseñamos un estudio prospectivo que incluyó 24 unidades de concentrado de hematíes, que habían sido transfundidos consecutivamente a pacientes de nuestro hospital. Luego de registrar el tiempo de conservación de cada bolsa, se extrajeron 15ml de sangre para determinar la actividad arginasa, los datos bioquímicos y de hemólisis. Se realizó un análisis univariante de todos los parámetros registrados y se incluyeron aquellos que resultaron significativos en un modelo de regresión múltiple (p<0,05). Resultados. El tiempo promedio de conservación fue de 18,6±6,1 días (rango: 6-31 días), con un hematocrito de 59,8%±0,05%, una hemoglobina 20,3±1,8g/dl, un pH de 6,5±0,1 y una actividad arginasa de 140,1±124,0 mU/ml. Se observó una relación lineal en el análisis univariante entre el tiempo de conservación y el pH (p=0,001), el HCO3act (p=0,001), el índice hemolítico (p=0,035) y la SpO2 (p=0,01). Una vez ajustados las variables de confusión procedentes del modelo univariante, se observó una relación lineal entre la actividad arginasa y el tiempo de conservación (p=0,031). Conclusiones. Nuestro trabajo muestra una relación lineal directamente proporcional entre el tiempo de conservación de los concentrados de hematíes y la actividad arginasa presente en los mismos. Sugerimos que estos hallazgos podrían estar relacionados con la elevada incidencia de complicaciones tras la transfusión que puede ser directamente proporcional a su tiempo de conservación(AU)

Objectives. Given the increasing evidence regarding a relationship between packed red blood cells storage time and post-transfusion complications, we decided to determine the relationship between the arginase enzyme levels, biochemical parameters and haemolysis, with the storage time of transfused packed red blood cells. Material and methods. We designed a prospective study that included 24 units of packed cells that had been consecutively transfused to patients of our hospital. After recording the storage time of each bag, 15ml of blood was removed to determine arginase activity, biochemical parameters and haemolysis. A univariate analysis was performed on all the recorded parameters, and included those that were significant in the multiple regression model (P<.05). Results. The mean storage time was 18.6±6.1 days (range: 6-31 days), with a haematocrit of 59.8%±0.05%, a haemoglobin of 20.3±1.8g/dl, a pH of 6.5±0.1, and an arginase activity of 140.1±124.0mU/ml. A linear relationship was observed in the univariate analysis between the storage time and the pH (P=.001), the actualHCO3 (P=.001), the haemolysis index (P=.035) and the SpO2 (P=.01). Once adjusted for the confounding variables of the univariate model, a linear relationship was observed between the arginase activity and the storage time (P=.031). Conclusions. Our study shows a directly proportional linear relationship between the storage time of packed red blood cells and their arginase activity. We suggest that these findings could be associated with the high incidence of complications after transfusion that may be directly proportional to their storage time(AU)

[Relationship between arginase activity and the storage time of packed red blood cells]. / Relación entre la actividad arginasa y el tiempo de conservación de los concentrados de hematíes.

OBJECTIVES: Given the increasing evidence regarding a relationship between packed red blood cells storage time and post-transfusion complications, we decided to determine the relationship between the arginase enzyme levels, biochemical parameters and haemolysis, with the storage time of transfused packed red blood cells. MATERIAL AND METHODS: We designed a prospective study that included 24 units of packed cells that had been consecutively transfused to patients of our hospital. After recording the storage time of each bag, 15 ml of blood was removed to determine arginase activity, biochemical parameters and haemolysis. A univariate analysis was performed on all the recorded parameters, and included those that were significant in the multiple regression model (P<.05). RESULTS: The mean storage time was 18.6±6.1 days (range: 6-31 days), with a haematocrit of 59.8%±0.05%, a haemoglobin of 20.3±1.8 g/dl, a pH of 6.5±0.1, and an arginase activity of 140.1±124.0 mU/ml. A linear relationship was observed in the univariate analysis between the storage time and the pH (P=.001), the actual HCO(3) (P=.001), the haemolysis index (P=.035) and the SpO(2) (P=.01). Once adjusted for the confounding variables of the univariate model, a linear relationship was observed between the arginase activity and the storage time (P=.031). CONCLUSIONS: Our study shows a directly proportional linear relationship between the storage time of packed red blood cells and their arginase activity. We suggest that these findings could be associated with the high incidence of complications after transfusion that may be directly proportional to their storage time.

Antitumor alkyl-lysophospholipid analog edelfosine induces apoptosis in pancreatic cancer by targeting endoplasmic reticulum.

Pancreatic cancer remains as one of the most deadly cancers, and responds poorly to current therapies. The prognosis is extremely poor, with a 5-year survival of less than 5%. Therefore, search for new effective therapeutic drugs is of pivotal need and urgency to improve treatment of this incurable malignancy. Synthetic alkyl-lysophospholipid analogs (ALPs) constitute a heterogeneous group of unnatural lipids that promote apoptosis in a wide variety of tumor cells. In this study, we found that the anticancer drug edelfosine was the most potent ALP in killing human pancreatic cancer cells, targeting endoplasmic reticulum (ER). Edelfosine was taken up in significant amounts by pancreatic cancer cells and induced caspase- and mitochondrial-mediated apoptosis. Pancreatic cancer cells show a prominent ER and edelfosine accumulated in this subcellular structure, inducing a potent ER stress response, with caspase-4, BAP31 and c-Jun NH(2)-terminal kinase (JNK) activation, CHOP/GADD153 upregulation and phosphorylation of eukaryotic translation initiation factor 2 α-subunit that eventually led to cell death. Oral administration of edelfosine in xenograft mouse models of pancreatic cancer induced a significant regression in tumor growth and an increase in apoptotic index, as assessed by TUNEL assay and caspase-3 activation in the tumor sections. The ER stress-associated marker CHOP/GADD153 was visualized in the pancreatic tumor isolated from edelfosine-treated mice, indicating a strong in vivo ER stress response. These results suggest that edelfosine exerts its pro-apoptotic action in pancreatic cancer cells, both in vitro and in vivo, through its accumulation in the ER, which leads to ER stress and apoptosis. Thus, we propose that the ER could be a key target in pancreatic cancer, and edelfosine may constitute a prototype for the development of a new class of antitumor drugs targeting the ER.

Involvement of lipid rafts in the localization and dysfunction effect of the antitumor ether phospholipid edelfosine in mitochondria.

Lipid rafts and mitochondria are promising targets in cancer therapy. The synthetic antitumor alkyl-lysophospholipid analog edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) has been reported to target lipid rafts. Here, we have found that edelfosine induced loss of mitochondrial membrane potential and apoptosis in human cervical carcinoma HeLa cells, both responses being abrogated by Bcl-x(L) overexpression. We synthesized a number of new fluorescent edelfosine analogs, which preserved the proapoptotic activity of the parent drug, and colocalized with mitochondria in HeLa cells. Edelfosine induced swelling in isolated mitochondria, indicating an increase in mitochondrial membrane permeability. This mitochondrial swelling was independent of reactive oxygen species generation. A structurally related inactive analog was unable to promote mitochondrial swelling, highlighting the importance of edelfosine molecular structure in its effect on mitochondria. Raft disruption inhibited mitochondrial localization of the drug in cells and edelfosine-induced swelling in isolated mitochondria. Edelfosine promoted a redistribution of lipid rafts from the plasma membrane to mitochondria, suggesting a raft-mediated link between plasma membrane and mitochondria. Our data suggest that direct interaction of edelfosine with mitochondria eventually leads to mitochondrial dysfunction and apoptosis. These observations unveil a new framework in cancer chemotherapy that involves a link between lipid rafts and mitochondria in the mechanism of action of an antitumor drug, thus opening new avenues for cancer treatment.

Prenylflavonoids and prenyl/alkyl-phloroacetophenones: synthesis and antitumour biological evaluation.

Several prenylflavonoids have been synthesised and tested against human tumour cell lines. The prenyl unit has been geranyl or a labdane diterpene. These labdane-flavonoids have been synthesised for the first time. The antitumour activity increase with the prenylation at C-8 position. Twenty-three C and O-prenylated acylphloroglucinols have been synthesised as well. In this case the C-alkylation products have resulted, in general, more active.

Lipid raft-targeted therapy in multiple myeloma.

Despite recent advances in treatment, multiple myeloma (MM) remains an incurable malignancy. By using in vitro, ex vivo and in vivo approaches, we have identified here that lipid rafts constitute a new target in MM. We have found that the phospholipid ether edelfosine targets and accumulates in MM cell membrane rafts, inducing apoptosis through co-clustering of rafts and death receptors. Raft disruption by cholesterol depletion inhibited drug uptake by tumor cells as well as cell killing. Cholesterol replenishment restored MM cell ability to take up edelfosine and to undergo drug-induced apoptosis. Ceramide addition displaced cholesterol from rafts, and inhibited edelfosine-induced apoptosis. In an MM animal model, edelfosine oral administration showed a potent in vivo antimyeloma activity, and the drug accumulated preferentially and dramatically in the tumor. A decrease in tumor cell cholesterol, a major raft component, inhibited the in vivo antimyeloma action of edelfosine and reduced drug uptake by the tumor. The results reported here provide the proof-of-principle and rationale for further clinical evaluation of edelfosine and for this raft-targeted therapy to improve patient outcome in MM. Our data reveal cholesterol-containing lipid rafts as a novel and efficient therapeutic target in MM, opening a new avenue in cancer treatment.

Comparative study of A HPLC-MS assay versus an UHPLC-MS/MS for anti-tumoral alkyl lysophospholipid edelfosine determination in both biological samples and in lipid nanoparticulate systems.

The anti-tumor agent edelfosine represents a promising option in the treatment of cancer due to its capacity of promoting apoptosis in tumor cells selectively, while sparing healthy ones. In the present study, a novel ultra high performance liquid chromatography-tandem mass spectrometry method (UHPLC-MS/MS) was developed to quantify edelfosine concentrations in biological matrices (plasma, tissues or tumor) and in lipid nanoparticles, and compared with a conventional high performance liquid chromatography-mass spectrometry method (HPLC-MS). Compared with the HPLC method, the UHPLC method offered a threefold decrease in retention time, and a twofold decrease in asymmetry USP factor. Both methods were validated. Calibration curves for the HPLC method (0.1-1 and 1-75 microg/mL range in the plasma samples, 1-75 microg/mL range in lipid nanoparticle samples and 0.2-31.75 microg/mL range in tissue homogenate samples), and UHPLC method (0.0075-75 microg/mL for all kind of samples) showed a linear range of detector response (r>0.999). Intra-batch and inter-batch precision ranged from 1.66% to 7.77% for the HPLC method and from 3.72% to 12.23% for the UHPLC method. Accuracy of the HPLC and UHPLC assays, expressed as bias, ranged from -5.83% to 7.13% and from -6.84% to 6.49%, respectively. Matrix effects on edelfosine were similar in the HPLC and UHPLC methods. The assay methods developed were successfully applied to the quality control procedure of the manufacture of edelfosine lipid nanoparticles, and to evaluate the pharmacokinetic and in vivo tissue distribution in mice after oral administration of edelfosine-loaded lipid nanoparticles. A good correlation between both techniques was found (r=0.953) when tissue samples were analyzed with both methods.

Involvement of mitochondria and recruitment of Fas/CD95 signaling in lipid rafts in resveratrol-mediated antimyeloma and antileukemia actions.

We have found that resveratrol (trans-3,4',5-trihydroxystilbene) induced apoptosis in multiple myeloma (MM) and T-cell leukemia cells through coclustering of Fas/CD95 death receptor and lipid rafts, whereas normal lymphocytes were spared. Tumor necrosis factor-related apoptosis-inducing ligand receptors, Fas-associated death domain-containing protein (FADD), procaspase-8, procaspase-10, c-Jun amino-terminal kinase and Bid were also recruited into lipid rafts on resveratrol incubation with MM and T-cell leukemia cells. Raft disruption inhibited resveratrol-induced apoptosis. Bcl-XL overexpression prevented resveratrol-induced disruption of mitochondrial transmembrane potential (DeltaPsi(m)) and apoptosis. A FADD dominant-negative mutant, that blocked Fas/CD95 downstream signaling, precluded resveratrol-induced DeltaPsi(m) loss and apoptosis, indicating a sequence of Fas/CD95 signaling-->mitochondrion in the apoptotic response triggered by resveratrol. Cells deficient in Fas/CD95 did not undergo resveratrol-induced apoptosis. Pretreatment of MM cells with interferon-gamma upregulated Fas/CD95 and caspase-8, and potentiated resveratrol-induced apoptosis. Our data indicate that recruitment of Fas/CD95 death receptor and downstream signaling molecules into lipid rafts, followed by DeltaPsi(m) disruption, underlies the apoptotic action of resveratrol in MM and T-cell leukemic cells. Combination of resveratrol with perifosine or bortezomib potentiated the apoptotic response induced by each single drug. These results also highlight the role of recruitment of Fas/CD95 signaling in lipid rafts in antimyeloma and antileukemia chemotherapy.

Proapoptotic role of Hsp90 by its interaction with c-Jun N-terminal kinase in lipid rafts in edelfosine-mediated antileukemic therapy.

Heat shock protein 90 (Hsp90) is a survival signaling chaperone and a cancer chemotherapeutic target. However, we have found that inhibitors of Hsp90 diminished the apoptotic response induced in leukemic cells by the antitumor alkyl-lysophospholipid analog edelfosine, which acts through lipid raft reorganization. Edelfosine treatment recruited Hsp90, c-Jun N-terminal kinase (JNK) and apoptotic molecules in lipid rafts, but not the JNK regulators apoptosis signal-regulating kinase 1 (ASK1) and Daxx, or the survival signaling molecules extracellular signal-regulated kinase (ERK) and Akt. Following edelfosine treatment, Hsp90 bound to JNK in lipid rafts and Hsp90-JNK clusters were identified at the plasma membrane by immunoelectron microscopy. Hsp90 inhibition reduced JNK protein level in lipid rafts and turned proapoptotic persistent JNK activation into a transient response in edelfosine-treated cells. Decrease in edelfosine-induced JNK activation and apoptosis by Hsp90 inhibition was prevented through proteasome inhibition, suggesting that Hsp90 inhibition diminishes apoptosis by promoting JNK protein degradation. Expression of ASK1 dominant negative mutant did not affect JNK activation and apoptosis following edelfosine treatment. These data indicate that lipid raft-recruited JNK is ASK1-independent and becomes a novel Hsp90 client protein. Our results reveal a new chaperoning role of Hsp90 on JNK-mediated apoptosis following its recruitment in lipid rafts.

Synthesis of novel antitumoural analogues of dysidiolide from ent-halimic acid.

Several sesterterpenolides analogues of dysidiolide have been synthesized and their in vitro antitumoural activity against human HeLa, A549, HT-29 and HL-60 carcinoma cells is presented. The proliferation inhibition data showed a significant antitumour activity of the compounds 1b, 2a, 2b, 3a, 3b, 4a, 4b, 5, inhibiting proliferation of distinct cancer cell types with an IC(50) in the low micromolar range.

Granulos de neutrófilos humanos y control molecular de su exocitosis / Human neutrophil granules and exocytosis molecular control

Los leucocitos polimorfonucleares neutrófilos (PMNs) constituyen la primera línea de defensa frente a la infección y juegan un papel fundamental en los procesos inflamatorios. Estas acciones de los neutrófilos se deben en gran medida a sus gránulos citoplásmicos, algunos de los cuales se movilizan con dificultad tras la activación celular, los gránulos azurófilos (primarios), mientras que otros sufren fácilmente exocitosis tras la activación celular, los gránulos específicos (secundarios), los gránulos terciarios ricos en gelatinasa y las vesículas secretoras (fosfasomas). Estos últimos son de naturaleza endocítica. Los gránulos azurófilos contienen una gran cantidad de enzimas líticas que pueden ser perjudiciales para el tejido adyacente si se secretaran de una forma desregulada. Los gránulos específicos y terciarios constituyen un reservorio de proteínas de la membrana plasmática que se incorporan a la superficie celular tras la activación del neutrófilo, y contienen un gran número de proteínas implicadas en la adhesión y extravasación de los neutrófilos humanos. De esta forma, la secreción de los gránulos del neutrófilo debe estar fuertemente controlada para prevenir la liberación desregulada de constituyentes dañinos o procesos inflamatorios. Las bases moleculares de la secreción en el neutrófilo están comenzando a ser desveladas solo en los últimos años. Se han identificado un cierto número de proteínas SNARE en neutrófilos humanos, y algunas de ellas, tales como SNAP-23, VAMP-2, y sintaxinas 4 y 6, han sido recientemente implicadas en la exocitosis de las distintas poblaciones de gránulos. Además, se ha sugerido la participación de proteínas adicionales en el control de secreción de los gránulos del neutrófilo mediada por Ca2+ y GTP, incluyendo sinaptotagmina, anexinas y proteínas G de bajo peso molecular. La identificación de las moléculas esenciales para la secreción de los gránulos del neutrófilo puede conducir a nuevas dianas terapéuticas en el tratamiento de la inflamación (AU)

Microtubules, microtubule-interfering agents and apoptosis.

Microtubules are dynamic polymers that play crucial roles in a large number of cellular functions. Their pivotal role in mitosis makes them a target for the development of anticancer drugs. Microtubule-damaging agents suppress microtubule dynamics, leading to disruption of the mitotic spindle in dividing cells, cell cycle arrest at M phase, and late apoptosis. A better understanding of the processes coupling microtubule damage to the onset of apoptosis will reveal sites of potential intervention in cancer chemotherapy. Inhibition of microtubule dynamics induces persistent modification of biological processes (M arrest) and signaling pathways (mitotic spindle assembly checkpoint activation, Bcl-2 phosphorylation, c-Jun NH(2)-terminal kinase activation), which ultimately lead to apoptosis through the accumulation of signals that finally reach the threshold for the onset of apoptosis or through diminishing the threshold for engagement of cell death. Microtubules serve also as scaffolds for signaling molecules that regulate apoptosis, such as Bim and survivin, and their release from microtubules affect the activities of these apoptosis regulators. Thus, sustained modification of signaling routes and changes in the scaffolding properties of microtubules seem to constitute two major processes in the apoptotic response induced by microtubule-interfering agents.

Synthesis of bioactive sesterterpenolides from ent-halimic acid. 15-epi-ent-Cladocoran A and B.

The bioactive sesterterpenoid gamma-hydroxybutenolides 15,18-bisepi-ent-Cladocoran A and B, 1 and 2, and 15-epi-ent-Cladocoran A and B, 57 and 55, were synthesized from ent-halimic acid. The synthesized sesterterpenolids 2, 55, 57, and 59 inhibited cellular proliferation (IC(50) congruent with 2 micro M) of a number of human leukaemic and solid tumor cell lines.