Explore the vast range of titles available.

Boron nitride nanotubes (BNNTs) represent an extremely interesting class of nanomaterials, and recent findings have suggested a number of applications in the biomedical field. Anyhow, extensive biocompatibility investigations are mandatory before any further advancement toward preclinical testing. Here, we report on the effects of multiwalled BNNTs in freshwater planarians, one of the best-characterized in vivo models for developmental biology and regeneration research. Obtained results indicate that BNNTs are biocompatible in the investigated model, since they do not induce oxidative DNA damage and apoptosis, and do not show adverse effects on planarian stem cell biology and on de novo tissue regeneration. In summary, collected findings represent another important step toward BNNT realistic applications in nanomedicine.

Cardiac glycosides (CGs), prescribed to treat cardiovascular alterations, display potent anti-cancer activities. Despite their well-established target, the sodium/potassium (Na + /K + )-ATPase, downstream mechanisms remain poorly elucidated. UNBS1450 is a hemi-synthetic cardenolide derived from 2″-oxovorusharin extracted from the plant Calotropis procera , which is effective against various cancer cell types with an excellent differential toxicity. By comparing adherent and non-adherent cancer cell types, we validated Mcl-1 as a general and early target of UNBS1450. A panel of CGs including cardenolides ouabain, digitoxin and digoxin as well as bufadienolides cinobufagin and proscillaridin A allowed us to generalize our findings. Our results show that Mcl-1, but not Bcl-xL nor Bcl-2, is rapidly downregulated prior to induction of apoptosis. From a mechanistic point of view, we exclude an effect on transcription and demonstrate involvement of a pathway affecting protein stability and requiring the proteasome in the early CG-induced Mcl-1 downregulation, without the involvement of caspases or the BH3-only protein NOXA. Strategies aiming at preventing UNBS1450-induced Mcl-1 downregulation by overexpression of a mutated, non-ubiquitinable form of the protein or the use of the proteasome inhibitor MG132 inhibited the compound’s ability to induce apoptosis. Altogether our results point at Mcl-1 as a ubiquitous factor, downregulated by CGs, whose modulation is essential to achieve cell death.

Chemoresistance and therapeutic selectivity are major obstacles to successful chemotherapy of ovarian cancer. Manganese superoxide disumutase (MnSOD) is an important antioxidant enzyme responsible for the elimination of superoxide radicals. We reported here that MnSOD was significantly elevated in ovarian cancer cells and its overexpression was one of the mechanisms that increased resistance to apoptosis in cancer cells. Knockdown of MnSOD by small-interfering RNA (siRNA) led to an increase in superoxide generation and sensitisation of ovarian cancer cells to the two front-line anti-cancer agents doxorubicin and paclitaxel whose action involved free-radical generation. This synergistic effect was not observed in non-transformed ovarian surface epithelial cells. Furthermore, our results revealed that this combination at the cellular level augmented activation of caspase-3 and caspase-9, but not caspase-8, suggesting involvement of an intrinsic apoptotic pathway. Evaluation of signalling pathways showed that MnSOD siRNA enhanced doxorubicin- and paclitaxel-induced phosphorylation of extracellular signal-regulated kinase 1/2. Akt activation was not affected. These results identify a novel chemoresistance mechanism in ovarian cancer, and show that combination of drugs capable of suppressing MnSOD with conventional chemotherapeutic agents may provide a novel strategy with a superior therapeutic index and advantage for the treatment of refractory ovarian cancer.

Prostate cancer develops from clones that are already present as early as thirty-five years of age, when circulating concentrations of androgens are high. The progression of the disease is low and the cancer is diagnosed at a more advanced age. Prostate cancer evolves from an androgen dependant stage to stage where it escapes from all antiandrogenic treatments. The patient usually dies within two years following the diagnosis of advanced cancer. Therefore, it is of great interest to develop new therapies for androgen independent prostate cancer. The androgen independent evolution of prostate cancer is a complex phenomenon at the cellular and molecular levels. It includes an increased sensitivity to growth factors, the control of proliferation pathways, apoptotic and survival pathways as well as the control of angiogenesis. Epidemiological studies have also suggested that certain vitamins or phyto-oestrogens could protect against prostate cancer development. The present review attempts to present an overview of the fundamental research in cellular signalling which could be interesting as target for the treatment of androgen independent prostate cancer. Also the potential interest of non-androgenic steroids was reviewed for the same goal.

NF-kappaB has been implicated in the regulation of apoptosis, a key mechanism of normal and malignant growth control. Previously, we demonstrated that inhibition of NF-kappaB activity by TGF-beta1 leads directly to induction of apoptosis of murine B-cell lymphomas and hepatocytes. Thus, we were surprised to determine that NF-kappaB is transiently activated in response to TGF-beta1 treatment. Here we elucidate the mechanism of TGF-beta1-mediated regulation of NF-kappaB and induction of apoptosis in epithelial cells. We report that TGF-beta1 activates IKK kinase, which mediates IkappaB-alpha phosphorylation. In turn, the activation of IKK following TGF-beta1 treatment is mediated by the TAK1 kinase. As a result of NF-kappaB activation, IkappaB-alpha mRNA and protein levels are increased leading to postrepression of NF-kappaB and induction of cell death. Inhibition of NF-kappaB following TGF-beta1 treatment increased AP-1 complex transcriptional activity through sustained c-Jun phosphorylation, thereby potentiating AP-1/SMADs-mediated cell killing. Furthermore, TGF-beta1-mediated upregulation of Smad7 appeared independent of NF-kappaB. In hepatocellular carcinomas of TGF-beta1 or TGF-alpha/c-myc transgenic mice, we observed constitutive activation of NF-kappaB that led to inhibition of JNK signaling. Overall, our data illustrate an autocrine mechanism based on the ability of IKK/NF-kappaB/IkappaB-alpha signaling to negatively regulate NF-kappaB levels thereby permitting TGF-beta1-induced apoptosis through AP-1 activity.

Short, high-concentration peaks of the atmospheric pollutant ozone (O₃) cause the formation of cell death lesions on the leaves of sensitive plants. Numerous similarities between the plant responses to O₃ and pathogens suggest that O₃ triggers hypersensitive response-like programmed cell death (PCD). We examined O₃ and superoxide-induced cell death in the O₃-sensitive radical-induced cell death1 (rcd1) mutant. Dying cells in O₃-exposed rcd1 exhibited several of the typical morphological characteristics of the hypersensitive response and PCD. Double-mutant analyses indicated a requirement for salicylic acid and the function of the cyclic nucleotide-gated ion channel AtCNGC2 in cell death. Furthermore, a requirement for ATPases, kinases, transcription, Ca²⁺ flux, caspase-like proteolytic activity, and also one or more phenylmethylsulfonyl fluoride-sensitive protease activities was shown for the development of cell death lesions in rcd1. Furthermore, mitogen-activated protein kinases showed differential activation patterns in rcd1 and Columbia. Taken together, these results directly demonstrate the induction of PCD by O₃.

Wang, B., Ohyama, H., Shang, Y., Fujita, K., Tanaka, K., Nakajima, T., Aizawa, S., Yukawa, O. and Hayata, I. Adaptive Response in Embryogenesis: IV. Protective and Detrimental Bystander Effects Induced by X Radiation in Cultured Limb Bud Cells of Fetal Mice. Radiat. Res. 161, 9–16 (2004). The radioadaptive response and the bystander effect represent important phenomena in radiobiology that have an impact on novel biological response mechanisms and risk estimates. Micromass cultures of limb bud cells provide an in vitro cellular maturation system in which the progression of cell proliferation and differentiation parallels that in vivo. This paper presents for the first time evidence for the correlation and interaction in a micromass culture system between the radioadaptive response and the bystander effect. A radioadaptive response was induced in limb bud cells of embryonic day 11 ICR mice. Conditioning irradiation of the embryonic day 11 cells with 0.3 Gy resulted in a significant protective effect against the occurrence of apoptosis, inhibition of cell proliferation, and differentiation induced by a challenging dose of 5 Gy given the next day. Both protective and detrimental bystander effects were observed; namely, irradiating 50% of the embryonic day 11 cells with 0.3 Gy led to a successful induction of the protective effect, and irradiating 70% of the embryonic day 12 cells with 5 Gy produced a detrimental effect comparable to that seen when all the cells were irradiated. Further, the bystander effect was markedly decreased by pretreatment of the cells with an inhibitor to block the gap junction-mediated intercellular communication. These results indicate that the bystander effect plays an important role in both the induction of a protective effect by the conditioning dose and the detrimental effect of the challenge irradiation. Gap junction-mediated intercellular communication was suggested to be involved in the induction of the bystander effect.

Methamphetamine (METH) is a psychostimulant. The precise mechanisms of its effects remain unknown and current relapse treatments have low efficacy. However, brain-derived neurotrophic factor (BDNF) and neuronal plasticity are essential contributors, despite paradoxical reports and a lack of comprehensive studies. Therefore, we investigated the effects of different doses of METH on long-term potentiation (LTP), BDNF expression and neuronal apoptosis in the hippocampus of reinstated rats. Rats were injected intraperitoneally with METH (1, 5, or 10 mg/kg) or saline, and trained in a conditioned place preference paradigm. Following implementation of the reinstatement model, electrophysiology, western blotting and TUNEL assay were performed to assess behavior, LTP components, BDNF expression, and neuronal apoptosis, respectively. The results demonstrated that the preference scores, population spike amplitude and BDNF expression markedly decreased in the METH (10 mg/kg) group compared with the other groups. In contrast, METH (5 mg/kg) significantly increased these factors more than the control group. There was no change in variables between METH (1 mg/kg) and the control group. Also, apoptosis of the hippocampus was increased in the METH (10 mg/kg) group compared with the METH (5 mg/kg) group. These results suggest that alterations in synaptic plasticity, expression of BDNF and neuronal apoptosis in the hippocampus has a vital role in the context-induced reinstatement of METH seeking.

Pyridoxine (vitamin B6) toxicity is a well-known model for peripheral neuropathy. GABA and glutamate are two neurotransmitters in neural pathways involved in the peripheral neuropathy. Cichorium intybus (Chicory) contains glycosides and triterpenoids, which inhibit glutamatergic transmission and enhance GABAergic transmission. The present study was aimed at studying the effect of chicory extract (CE) on the pyridoxine-induced peripheral neuropathy with a particular focus on glutamatergic and GABAergic systems. In this experimental study, a high dose of pyridoxine (800 mg/kg, i.p.) was injected for 14 days to induce neuropathy in male rats. To evaluate the behavioral symptoms, three tests including rotarod, hot plate, and foot fault were used. After the induction of neuropathy, CE (50 mg/kg i.p.) was injected intraperitoneally for 10 consecutive days. Morphologically, the sciatic nerve and the DRG neurons were evaluated in the control, neuropathy, and chicory groups by H&E staining. For evaluating the mechanism, picrotoxin (1 mg/kg) and MK-801 (0.1 mg/kg) were also individually injected 15 min before the extract administration. The concentration of TNF-α in rat sciatic nerve and DRG neurons were also measured by enzyme-linked-immunoassay (ELISA). Morphological and physiological changes occurred in the DRG and sciatic nerve following pyridoxine intoxication. The CE exerted an anti-neuropathic effect on the sciatic nerve and DRG neurons and also decreased reaction time in hot plate test (p < 0.05), increased balance time in rotarod test (p < 0.001), and improved foot fault performance (p < 0.01). Moreover, CE administration reduced TNF-α level in DRG (p < 0.001) and sciatica nerve (p < 0.001). Picrotoxin, unlike MK-801, showed a significant difference in all three behavioral tests and reduced TNF-α content in comparison with group received extraction alone (with p < 0.001 for all three tests). Our results showed beneficial effects of CE on pyridoxine-induced peripheral neuropathy. Modulating of the GABAergic system mediated by TNF-α may be involved in the anti-neurotoxic effect of CE.

Leaves of Eucommia ulmoidesOliv. harvested between April to November were examined for programmed cell death (PCD) during growth and senescence. Leaves developed in April, becoming fully expanded in late May, remaining unchanged until November when they started to dehisce. Falling leaves retained a green color. Our results showed that (1) mesophyll cells gradually reduced their nuclei from September to November, (2) positive TUNEL signals appeared on the nuclei from August, (3) ladder-like DNA fragmentation occurred in September and October, and (4) a 20-kDa Ca(2+)-dependent DNase appeared in these same months. In fallen leaves, intact mesophyll cell nuclei could not be detected, but a few cells around the vascular bundle had nuclei. Therefore, (1) programmed cell death (PCD) of leaf cells occurred in the leaves of E. ulmoides, (2) the progress of mesophyll cell PCD lasted for more than 2 months, and (3) PCD of leaf cells was asynchronous in natural senescing leaves.