Locally advanced rectal cancers are treated with neoadjuvant chemoradiation therapy followed by surgery. In a minority (~20%) of patients, no tumor is present at the time of surgery; these patients ...with a complete pathologic response (pathCR) to neoadjuvant therapy have better treatment outcomes. Unfortunately, the inherent radioresistance of colorectal cancer (CRC) cells dictates that the majority of patients do not achieve a pathCR. Efforts to improve these odds have fueled the search for novel, relatively less‐toxic radiosensitizers with distinct molecular mechanism(s) and broad‐spectrum anticancer activities. Here, we use zerumbone, a sesquiterpene from the edible ginger (Zingiber zerumbet Smith), to enhance radiosensitivity of CRC cells. Short exposure to zerumbone (7 h) profoundly sensitized CRC cells, independent of their p53 or k‐RAS status. Zerumbone enhanced radiation‐induced cell cycle arrest (G2/M), increased radiation‐induced apoptosis, but induced little apoptosis by itself. Zerumbone significantly enhanced radiation‐induced DNA damage, as evident by delayed resolution of post‐irradiation nuclear γH2AX foci, whereas zerumbone treatment alone did not induce γH2AX foci formation. Zerumbone pretreatment inhibited radiation‐induced nuclear expression of DNA repair proteins ataxia‐telangiectasia mutated (ATM) and DNA‐PKcs. Interestingly, zerumbone‐mediated radiosensitization did not involve reactive oxygen species (ROS), but was mediated through depletion of cellular glutathione (GSH). Ability of only thiol‐based antioxidants to abrogate zerumbone‐mediated radiosensitization further corroborated this hypothesis. The α,β‐unsaturated carbonyl group in zerumbone was found to be essential for its bioactivity as zerumbone analog α‐Humulene that lacks this functional group, could neither radiosensitize CRC cells, nor deplete cellular GSH. Our studies elucidate novel mechanism(s) of zerumbone's ability to enhance CRC radiosensitivity.
Though sesquiterpene zerumbone has been shown to have antiproliferative and anticarcinogenic activities in colorectal cancer (CRC); no reports document its potential for and mechanism of CRC radiosensitization. Our studies, for the first time show potent radiosensitizing properties of zerumbone in CRC cells, and also for the first time report zerumbone's ability to enhance radiation‐induced DNA damage. This study suggests a novel cellular glutathione‐dependent mechanism of radiosensitization that is independent of reactive oxygen species generation.
Bronchopulmonary dysplasia (BPD), a common chronic respiratory disease that occurs after premature birth, is believed to be secondary to oxidative damage from hyperoxia and inflammation, which leads ...to impaired alveolar formation and chronic lung dysfunction. We hypothesized that extracellular superoxide dismutase (SOD)3, an antioxidant uniquely targeted to the extracellular matrix (ECM) and alveolar fluid, might have a different response (down-regulation) to hyperoxic injury and recovery in room air (RA), thereby contributing to the persistent airspace injury and inflammation. We used a murine BPD model using postnatal hyperoxia (O2) (4 or 5 d) followed by short-term recovery (14 d) in RA, which mimics the durable effects after injury during alveolar development. This was associated with significantly increased mRNA expression for antioxidant genes mediated by nuclear factor erythroid 2-related factor (Nrf2) in the O2 (n = 4) versus RA group (n = 5). SOD3, an Nrf2-independent antioxidant, was significantly reduced in the O2-exposed mice compared with RA. Immunohistochemistry revealed decreased and disrupted SOD3 deposition in the alveolar ECM of O2-exposed mice. Furthermore, this distinct hyperoxic antioxidant and injury profile was reproducible in murine lung epithelial 12 cells exposed to O2. Overexpression of SOD3 rescued the injury measures in the O2-exposed cells. We establish that reduced SOD3 expression correlates with alveolar injury measures in the recovered neonatal hyperoxic lung, and SOD3 overexpression attenuates hyperoxic injury in an alveolar epithelial cell line. Such findings suggest a candidate mechanism for the pathogenesis of BPD that may lead to targeted interventions.
Chronic obstructive pulmonary disease (COPD) is a prevalent smoking-related disease for which no disease-altering therapies currently exist. As dysregulated TGF-β signaling associates with lung ...pathology in patients with COPD and in animal models of lung injury induced by chronic exposure to cigarette smoke (CS), we postulated that inhibiting TGF-β signaling would protect against CS-induced lung injury. We first confirmed that TGF-β signaling was induced in the lungs of mice chronically exposed to CS as well as in COPD patient samples. Importantly, key pathological features of smoking-associated lung disease in patients, e.g., alveolar injury with overt emphysema and airway epithelial hyperplasia with fibrosis, accompanied CS-induced alveolar cell apoptosis caused by enhanced TGF-β signaling in CS-exposed mice. Systemic administration of a TGF-β-specific neutralizing antibody normalized TGF-β signaling and alveolar cell death, conferring improved lung architecture and lung mechanics in CS-exposed mice. Use of losartan, an angiotensin receptor type 1 blocker used widely in the clinic and known to antagonize TGF-β signaling, also improved oxidative stress, inflammation, metalloprotease activation and elastin remodeling. These data support our hypothesis that inhibition of TGF-β signaling through angiotensin receptor blockade can attenuate CS-induced lung injury in an established murine model. More importantly, our findings provide a preclinical platform for the development of other TGF-β-targeted therapies for patients with COPD.
The alveolar compartment, the fundamental gas exchange unit in the lung, is critical for tissue oxygenation and viability. We explored hepatocyte growth factor (HGF), a pleiotrophic cytokine that ...promotes epithelial proliferation, morphogenesis, migration, and resistance to apoptosis, as a candidate mediator of alveolar formation and regeneration. Mice deficient in the expression of the HGF receptor Met in lung epithelial cells demonstrated impaired airspace formation marked by a reduction in alveolar epithelial cell abundance and survival, truncation of the pulmonary vascular bed, and enhanced oxidative stress. Administration of recombinant HGF to tight-skin mice, an established genetic emphysema model, attenuated airspace enlargement and reduced oxidative stress. Repair in the TSK/+ mouse was punctuated by enhanced akt and stat3 activation. HGF treatment of an alveolar epithelial cell line not only induced proliferation and scattering of the cells but also conferred protection against staurosporine-induced apoptosis, properties critical for alveolar septation. HGF promoted cell survival was attenuated by akt inhibition. Primary alveolar epithelial cells treated with HGF showed improved survival and enhanced antioxidant production. In conclusion, using both loss-of-function and gain-of-function maneuvers, we show that HGF signaling is necessary for alveolar homeostasis in the developing lung and that augmentation of HGF signaling can improve airspace morphology in murine emphysema. Our studies converge on prosurvival signaling and antioxidant protection as critical pathways in HGF-mediated airspace maintenance or repair. These findings support the exploration of HGF signaling enhancement for diseases of the airspace.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Respiratory dysfunction is a major contributor to morbidity and mortality in aged populations. The susceptibility to pulmonary insults is attributed to "low pulmonary reserve", ostensibly reflecting ...a combination of age-related musculoskeletal, immunologic and intrinsic pulmonary dysfunction.
Using a murine model of the aging lung, senescent DBA/2 mice, we correlated a longitudinal survey of airspace size and injury measures with a transcriptome from the aging lung at 2, 4, 8, 12, 16 and 20 months of age. Morphometric analysis demonstrated a nonlinear pattern of airspace caliber enlargement with a critical transition occurring between 8 and 12 months of age marked by an initial increase in oxidative stress, cell death and elastase activation which is soon followed by inflammatory cell infiltration, immune complex deposition and the onset of airspace enlargement. The temporally correlative transcriptome showed exuberant induction of immunoglobulin genes coincident with airspace enlargement. Immunohistochemistry, ELISA analysis and flow cytometry demonstrated increased immunoglobulin deposition in the lung associated with a contemporaneous increase in activated B-cells expressing high levels of TLR4 (toll receptor 4) and CD86 and macrophages during midlife. These midlife changes culminate in progressive airspace enlargement during late life stages.
Our findings establish that a tissue-specific aging program is evident during a presenescent interval which involves early oxidative stress, cell death and elastase activation, followed by B lymphocyte and macrophage expansion/activation. This sequence heralds the progression to overt airspace enlargement in the aged lung. These signature events, during middle age, indicate that early stages of the aging immune system may have important correlates in the maintenance of tissue morphology. We further show that time-course analyses of aging models, when informed by structural surveys, can reveal nonintuitive signatures of organ-specific aging pathology.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract only
Lung inflammatory diseases, such as chronic obstructive pulmonary disease (COPD), are the third leading cause of death in United States. The disruption of gas exchange observed in COPD ...is a consequence of alveolar enlargement. Previous results from our laboratory showed that hepatocyte growth factor (HGF) administration in both an elastase‐induced emphysema mouse model and a genetic emphysema model significantly reduced airspace damage. Since hepatocyte growth factor (HGF) is a pleiotrophic cytokine that promotes epithelial proliferation, morphogenesis, migration, angiogenesis and survival, we investigated the cell‐autonomous effects of HGF in alveolar epithelial cell line. MLE‐12 cells were treated with HGF to study downstream mediators, proliferation, protection against apoptosis and scattering. We found that the prosurvival ERK and AKT pathways were activated in the presence of HGF. Using specific inhibitors, we found that basal and HGF‐induced proliferation was mediated through ERK signaling. However, HGF was shown to confer protection against cell death principally by AKT signaling. Finally, we demonstrated that HGF could induce MLE12 cell scattering after 1 hour of treatment. Together, the results obtained in this study showed that MLE12 cells are a good model system to dissect the role of HGF in the critical events of alveolar septation. Supported by grant to E.R.N (RO1‐HL085312).
The alveolar compartment, the fundamental gas exchange unit in the lung, is critical for tissue oxygenation and viability. We explored hepatocyte growth factor (HGF), a pleiotrophic cytokine that ...promotes epithelial proliferation, morphogenesis, migration, and resistance to apoptosis, as a candidate mediator of alveolar formation and regeneration. Mice deficient in the expression of the HGF receptor Met in lung epithelial cells demonstrated impaired airspace formation marked by a reduction in alveolar epithelial cell abundance and survival, truncation of the pulmonary vascular bed, and enhanced oxidative stress. Administration of recombinant HGF to tight-skin mice, an established genetic emphysema model, attenuated airspace enlargement and reduced oxidative stress. Repair in the TSK/+ mouse was punctuated by enhanced akt and stat3 activation. HGF treatment of an alveolar epithelial cell line not only induced proliferation and scattering of the cells but also conferred protection against staurosporine-induced apoptosis, properties critical for alveolar septation. HGF promoted cell survival was attenuated by akt inhibition. Primary alveolar epithelial cells treated with HGF showed improved survival and enhanced antioxidant production. In conclusion, using both loss-of-function and gain-of-function maneuvers, we show that HGF signaling is necessary for alveolar homeostasis in the developing lung and that augmentation of HGF signaling can improve airspace morphology in murine emphysema. Our studies converge on prosurvival signaling and antioxidant protection as critical pathways in HGF-mediated airspace maintenance or repair. These findings support the exploration of HGF signaling enhancement for diseases of the airspace.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A 2
factorial design was used to evaluate the influence of temperature, catalyst and time and esterification degree (DE) of pectin obtained from mango, orange and tangerine peels as well as tamarind ...seeds by using the acid hydrolysis method. The study showed that a high temperature positively influenced the percentage of pectin yield for the four second generation biomasses. Nevertheless, the temperature showed a greater influence in the solubility and diffusion of the acid solvent in the tamarind seed matrix, resulting a pectin recovery 32.9%. Concerning the %DE, the most statistically significant value observed was dependent on the type of biomass studied. The %DE and the nature of the pectin are determining factors in the pectin's final use, in the present work the pectin extracted was used to produce furfural, a precursor of high value chemicals. The furfural production was achieved through alkaline hydrolysis and enhanced using the Maillard reaction, reaching a maximum concentration of 71.8 g/L which represents a 42.1% increase from the alkaline hydrolysis.
The excess of mango peels is considered manufacturing waste in the sugar and juice industry. There is an increasing interest in looking for alternative ways to employ this waste to address this ...overload. Here, we show the efficient use of mango peels as a noncost carbon source for the synthesis of graphene. We demonstrate for the first time the synthesis of graphene on Cu substrates from mango peels, a biomass rich in pectin. It is observed that plasma presence is essential for the growth of graphene from mango peels. At 15 and 30 min of plasma exposure, we observed the presence of multilayered graphene, at longer plasma exposure, i.e., 60 min, there is the formation of monolayer graphene, attributed to the etching of multiple layers formed at short times due to long plasma exposure time. When employing this technique, precautions must be taken due to the etching effect of plasma, such as reducing either the plasma exposure time or the plasma power. Finally, we present a graphene growth pathway under plasma environment on the basis of our experimental observations.
SIRT7 is a NAD+‐dependent deacetylase that controls important aspects of metabolism, cancer, and bone formation. However, the molecular targets and functions of SIRT7 in the kidney are currently ...unknown. In silico analysis of kidney transcripts of the BXD murine genetic reference population revealed a positive correlation between Sirt7 and Slc12a7 mRNA expression, suggesting a link between the corresponding proteins that these transcripts encode, SIRT7, and the K‐Cl cotransporter KCC4, respectively. Here, we find that protein levels and activity of heterologously expressed KCC4 are significantly modulated depending on its acetylation status in Xenopus laevis oocytes. Moreover, SIRT7 interacts with KCC4 in a NAD+‐dependent manner and increases its stability and activity in HEK293 cells. Interestingly, metabolic acidosis increases SIRT7 expression in kidney, as occurs with KCC4. In contrast, total SIRT7‐deficient mice present lower KCC4 expression and an exacerbated metabolic acidosis than wild‐type mice during an ammonium chloride challenge. Altogether, our data suggest that SIRT7 interacts with, stabilizes and modulates KCC4 activity through deacetylation, and reveals a novel role for SIRT7 in renal physiology.
SYNOPSIS
The molecular targets and functions of SIRT7 in the kidney are currently unknown. This study demonstrates that SIRT7 interacts with, stabilizes and modulates KCC4 activity through deacetylation, and reveals a novel role for SIRT7 in renal physiology.
KCC4 protein levels and activity are modulated depending on its acetylation status.
SIRT7 interacts with KCC4 and increases its stability and activity through deacetylation.
Metabolic acidosis increased renal SIRT7 expression, while SIRT7‐deficient mice presented lower renal KCC4 expression.
SIRT7 interacts with, stabilizes and modulates KCC4 activity through deacetylation, revealing a novel role for SIRT7 in renal physiology.
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