Collagen gel protects L929 cells from TNFα-induced death by activating NF-κB

PURPOSE

Type I collagen is one of the most abundant components of extracellular matrix. We previously illustrated that murine fibrosarcoma L929 cells grew well on type I collagen gel and escaped from TNFα-induced cell death. In this study, we investigated the mechanism underlying the protective effect of collagen gel.

MATERIAL AND METHODS

We used western blot, confocal microscopy, MTT assay and flow cytometry by introducing fluorescence staining to determine the expression levels of nuclear factor kappa B (NF-κB), inhibitory ratio and autophagy.

RESULTS

L929 cells on collagen gel showed higher expression of NF-κB in the nucleus. Inhibition of NF-κB with pyrrolidine dithiocarbamate hydrochloride (PDTC) or knockdown by NF-κB-siRNA canceled the protective effect of collagen gel on L929 cells from TNFα-induced death, suggesting for the role of NF-κB in the protection from cell death. We found a new aspect of the effect of PDTC on L929 cells cultured on collagen gel. PDTC alone without TNFα induced apoptosis in the L929 cells cultured on collagen gel but not the cells on plastic dish. The apoptosis induction of the L929 cells cultured on collagen gel with PDTC was repressed by inhibiting autophagy with chloroquine, an autophagy inhibitor, suggesting that autophagy contributes to the death induced by the treatment with PDTC. Possible underlying mechanism of this finding is discussed.

CONCLUSION

NF-κB played an important role in protecting the L929 cells cultured on collagen gel from TNFα-induced death.

Silibinin ameliorates Aβ25-35-induced memory deficits in rats by modulating autophagy and attenuating neuroinflammation as well as oxidative stress

Alzheimer's disease (AD) is a progressive, neurodegenerative disease. Accumulating evidence suggests that inflammatory response, oxidative stress and autophagy are involved in amyloid β (Aβ)-induced memory deficits. Silibinin (silybin), a flavonoid derived from the herb milk thistle, is well known for its hepatoprotective activities. In this study, we investigated the neuroprotective effect of silibinin on Aβ_25-35-injected rats. Results demonstrated that silibinin significantly attenuated Aβ_25-35-induced memory deficits in Morris water maze and novel object-recognition tests. Silibinin exerted anxiolytic effect in Aβ_25-35-injected rats as determined in elevated plus maze test. Silibinin attenuated the inflammatory responses, increased glutathione (GSH) levels and decreased malondialdehyde (MDA) levels, and upregulated autophagy levels in the Aβ_25-35-injected rats. In conclusion, silibinin is a potential candidate for AD treatment because of its anti-inflammatory, antioxidant and autophagy regulating activities.

Activation of p53 contributes to pseudolaric acid B-induced senescence in human lung cancer cells in vitro

AIM

Pseudolaric acid B (PAB), a diterpene acid isolated from the root bark of Pseudolarix kaempferi Gordon, has shown to exert anti-tumor effects via inducing cell cycle arrest followed by apoptosis in several cancer cell lines. Here we reported that PAB induced a mitotic catastrophe in human lung cancer A549 cells, which resulted in senescence without apoptosis or necrosis.

METHODS

Three human lung cancer cell lines (A549, H460 and H1299 cells) were examined. Cell growth inhibition was assessed with MTT assay. Cell cycle distribution was determined using a flow cytometer. Cell nuclear morphology was observed under a fluorescence microscope. Senescent cells were detected using SA-β-Gal staining. Apoptotic and senescent protein expression was examined using Western blot analysis. The expression of p53 and p21 in the cells was downregulated by siRNAs.

RESULTS

Treatment with PAB (5-80 μmol/L) inhibited the growth of A549 cells in dose- and time-dependent manners. Prolonged treatment with PAB (20 μmol/L) caused G2/M arrest at day 1 followed by mitotic catastrophe from day 2, which eventually resulted in cell senescence between days 3 and 4 without cell death (apoptosis or necrosis). Knockdown of p53 expression with siRNA significantly suppressed PAB-induced senescence in A549 cells (p53 wild). Furthermore, PAB-induced senescence was also observed in human lung cancer H460 cells (p53 wild), but not in human lung cancer H1299 cells (p53 null).

CONCLUSION

The anti-tumor action of PAB against human lung cancer A549 cells in vitro involves the induction of senescence through activation of the p53 pathway.

Gelatin promotes murine fibrosarcoma L929 cell detachment and protects the cells from TNFα-induced cytotoxicity

PURPOSE

Gelatin has been considered to exist as intermediate substance of collagen catabolism in tissue remodeling or under inflammatory conditions. We have initiated the study on possible biological functions of gelatin that can exist temporally and locally under the conditions of remodeling and inflammation Materials and methods: To this purpose, we investigated cell proliferation and survival on gelatin-coated dishes and the response to tumor necrosis factor α (TNFα)-induced cytotoxicity in L929 cells. Autophagy level, ATP level, and ROS generation are examined.

RESULTS

L929 cells detached from the gelatin-coated dishes and formed multicellular aggregates. TNFα-induced cytotoxicity in L929 cells was inhibited by gelatin-coating culture. The cells on gelatin-coated dishes showed reduced cellular ATP levels and increased adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) phosphorylation, leading to increased ROS generation and autophagy.

CONCLUSION

This study showed that gelatin-coated culture protected L929 cells from TNFα-induced cytotoxicity and suggested for a possible pathophysiological function of gelatin in regulating cellular functions.

Vertical distribution of sediment phosphorus in Lake Hachirogata related to the effect of land reclamation on phosphorus accumulation

The focus of this work is the change in sediment properties and chemical characteristics that occur after land reclamation projects. The results indicate a higher sedimentation rate in Lake Hachirogata after reclamation, with the rate increasing with proximity to the agricultural zone. In the west-side water samples, higher levels of dissolved total nitrogen and dissolved total phosphorus (DTP) were found in both surface and bottom waters. The increase in P (39-80%) was generally greater than that for N (12-16%), regarding the nutrient supply from reclaimed farmland in the western part of the lake. In the eastern part of the lake, the pore-water Cl^- profile showed a decreasing vertical gradient in the sediment core. This indicates desalination of the lake water after construction of a sluice gate in 1961. In the western sediment-core sample, a uniform Cl^- profile indicates the mixing of lake water and pore water after reclamation. Considering the sedimentation of P in the last 100 years, there is a trend of increasing accumulation of P and P-activities after the reclamation project. This appears to be an impact from change in the lake environment as a result of increased agricultural nutrients, desalination, and residence. A large amount of mobile phosphorus (42-72% of TP in the western core sample) trapped in sediment increases the risk of phosphorus release and intensification of algal blooms. High sediment phosphorus and phosphorus mobility should be considered a source of pollution in the coastal environment.

Inhibition of caspase-9 by oridonin, a diterpenoid isolated from Rabdosia rubescens, augments apoptosis in human laryngeal cancer cells

Rabdosia rubescens, a commonly used traditional Chinese medicine, has increasingly gained attention for its use as an antitumor herb. Oridonin, a bioactive diterpenoid isolated from Rabdosia rubescens, has been reported to induce apoptosis in human laryngeal cancer HEp-2 cells by our group. Here, we made unexpected observations that the caspase-9 inhibitor (C9i) enhanced apoptosis in response to selected stimuli, and HEp-2 cells which were made deficient in caspase-9 using siRNA exhibited no resistance to apoptotic signals and actually demonstrated increased apoptotic sensitivity to oridonin. The results were reversed by the transfection of an exogenous caspase-9 expression vector. Caspase-9 reduced sensitivity to apoptotic stimuli through reactive oxygen species (ROS)-suppressing and autophagy-promoting methods. ROS triggered the progression of apoptosis through activation of both the caspase-9-independent mitochondrial pathway and death receptor pathways, and the autophagy had an anti-apoptotic function in oridonin-treated HEp-2 cells. These collective results suggest that oridonin targets caspase-9 to alter ROS production and autophagy situation to promote HEp-2 cell apoptosis. Therefore, oridonin has the potential to be developed as an anticancer agent, and the combination of oridonin with those agents leading to reduction of caspase-9 expression in tumor cells could represent a novel approach to human laryngeal cancer treatment.

ERα down-regulation plays a key role in silibinin-induced autophagy and apoptosis in human breast cancer MCF-7 cells

The estrogen receptor alpha (ERα) has been proven to be one of the most important therapeutic targets in breast cancer over the last 30 years. Previous studies pointed out that a natural flavonoid, silibinin, induced apoptosis in human breast cancer MCF-7 cells. In the present study we report that exposure of MCF-7 cells to silibinin led to cell death through the down-regulation of ERα expression. Silibinin-induced apoptosis of MCF-7 cells through up-regulation of caspase 6 due to ERα signalling repression was further boosted by ERα antagonist. Moreover, up-regulation of autophagy induced by silibinin accounted for apoptotic exacerbation, being further enhanced by ERα inhibition. Upon ERα activation, series of downstream signalling pathways can be activated. We found that silibinin reduced the expressions of Akt/mTOR and extracellular-signal-related kinase (ERK), which respectively accounted for the induction of autophagy and apoptosis. These effects were further augmented by co-treatment with ERα inhibitor. We conclude that the treatment with silibinin of ERα-positive MCF-7 cells down-regulates the expression of ERα, and subsequently mTOR and ERK signaling pathways, ERα downstream, finally resulting in induction of autophagy and apoptosis.

Effects of physical and morphometric factors on nutrient removal properties in agricultural ponds

Effects of physical and morphometric factors on nutrient removal properties were studied in small agricultural ponds with different depths, volumes, and residence times in western Japan. Average residence time was estimated to be >15 days, and it tended to decrease from summer to winter because of the increase in water withdrawal for agricultural activity. Water temperature was clearly different between the surface and bottom layers; this indicates that thermal stratification occurred in summer. Chlorophyll-a was significantly high (>20 μg/L) in the surface layer (<0.5 m) and influenced by the thermal stratification. Removal ratios of dissolved total nitrogen (DTN) and dissolved total phosphorus in the ponds were estimated to be 53-98% and 39-98% in August and 10-92% and 36-57% in December, respectively. Residence time of the ponds was longer in August than in December, and DTN removal, in particular, was more significant in ponds with longer residence time. Our results suggest residence time is an important factor for nitrogen removal in small agricultural ponds as well as large lakes.

Analysis of radiotherapy in 1054 patients with primary central nervous system lymphoma treated from 1985 to 2009

AIMS

Data on primary central nervous system lymphoma that had been collected through surveys for four consecutive periods between 1985 and 2009 were analysed to evaluate outcomes according to treatment.

MATERIALS AND METHODS

All had histologically proven disease and had received radiotherapy. No patients had AIDS. Among 1054 patients, 696 died and 358 were alive or lost to follow-up. The median follow-up period for surviving patients was 37 months.

RESULTS

For all patients, the median survival time was 24 months; the 5 year survival rate was 25.8%. Patients treated with methotrexate-based chemotherapy and radiation had a higher 5 year survival rate (43%) than those treated with radiation alone (14%) and those treated with non-methotrexate chemotherapy plus radiation (20%), but differences in relapse-free survival were smaller among the three groups. The 5 year survival rate was 25% for patients treated with whole-brain irradiation and 29% for patients treated with partial-brain irradiation (P = 0.80). Patients receiving a total dose of 40-49.9 Gy had a higher 5 year survival rate (32%) than those receiving other doses (21-25%, P = 0.0004) and patients receiving a whole-brain dose of 30-39.9 Gy had a higher 5 year survival rate (32%) than those receiving ≥40 Gy (13-22%, P < 0.0005). Patients receiving methotrexate-based chemotherapy and partial-brain radiotherapy (≥30 Gy) had a 5 year survival rate of 49%.

CONCLUSIONS

The optimal total and whole-brain doses may be in the range of 40-49.9 and <40 Gy, respectively, especially in combination with chemotherapy. Patients receiving partial-brain irradiation had a prognosis similar to that of those receiving whole-brain irradiation. With methotrexate-based chemotherapy, partial-brain radiotherapy may be worth considering for non-elderly patients with a single tumour.

Inhibition of c-Met promoted apoptosis, autophagy and loss of the mitochondrial transmembrane potential in oridonin-induced A549 lung cancer cells

OBJECTIVE

Herein, inhibition of hepatocyte growth factor receptor, c-Met, significantly increased cytochrome c release and Bax/Bcl-2 ratio, indicating that c-Met played an anti-apoptotic role. The following experiments are to elucidate this anti-apoptotic mechanism, then the effect of c-Met on autophagy has also been discussed.

METHODS

Investigated was the influence of c-Met on apoptosis, autophagy and loss of mitochondrial transmembrane potential (Δψm), and the relevant proteins were examined.

KEY FINDINGS

First, we found that activation of extracellular signal-regulated kinase (ERK), p53 was promoted by c-Met interference. Subsequent studies indicated that ERK was the upstream effector of p53, and this ERK-p53 pathway mediated release of cytochrome c and up-regulation of Bax/Bcl-2 ratio. Secondly, the inhibition of c-Met augmented oridonin-induced loss of mitochondrial transmembrane potential (Δψm), resulting apoptosis. Finally, the inhibition of c-Met increased oridonin-induced A549 cell autophagy accompanied by Beclin-1 activation and conversion from microtubule-associated protein light chain 3 (LC3)-I to LC3-II. Activation of ERK-p53 was also detected in autophagy process and could be augmented by inhibition of c-Met. Moreover, suppression of autophagy by 3-methyladenine (3-MA) or small interfering RNA against Beclin-1 or Atg5 decreased oridonin-induced apoptosis. Inhibition of apoptosis by pan-caspase inhibitor (z-VAD-fmk) decreased oridonin-induced autophagy as well and Loss of Δψm also occurred during autophagic process.

CONCLUSION

Thus, inhibiting c-Met enhanced oridonin-induced apoptosis, autophagy and loss of Δψm in A549 cells.

Silibinin protects murine fibroblast L929 cells from UVB-induced apoptosis through the simultaneous inhibition of ATM-p53 pathway and autophagy

Ultraviolet B (UVB) is a major cause of skin inflammation, leading to skin damage. Our previous in vivo study revealed that a natural flavonoid silibinin had marked anti-inflammatory effect on UVB-exposed murine skin. UVB exposure caused reduced autophagy in epidermis while it promoted autophagy in dermis. Nevertheless, silibinin inhibited the inflammatory flux in the skin epidermis as well as dermis through the modulation of autophagy. In order to elucidate the underlying protective mechanisms of silibinin for UVB damage on skin, separate studies on epidermis and dermis are helpful. Derived from the normal tissue of the mouse, L929 cells are capable of representing some characteristics of dermal cells. UVB irradiation caused L929 cell apoptosis in a time- and dose-dependent manner. Ataxia-telangiectasia-mutated (ATM) protein and p53 were activated to cause cell apoptosis, accompanying upregulation of the autophagic flux. The pharmacological inhibition of ATM, p53 and autophagy or the transfection with autophagy-associated protein-targeted small interfering RNAs showed that the UVB-activated ATM-p53 axis and autophagy formed a positive feedback loop, which synergistically promoted cell apoptosis. Silibinin treatment simultaneously repressed the activation of ATM-p53 and autophagy and thereby protected UVB-irradiated L929 cells from apoptotic death.

Physalin A induces apoptosis via p53-Noxa-mediated ROS generation, and autophagy plays a protective role against apoptosis through p38-NF-κB survival pathway in A375-S2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Physalin A is a bioactive withanolide isolated from natural plant Physalis alkekengi L. var. franchetii (Mast.) Makino, a traditional Chinese herbal medicine named Jindenglong which has long been used for the treatment of cough, sore throat, hepatitis, eczema, dysuria and tumors in China.

AIM OF THE STUDY

Based on the previous study that physalin A induced cytotoxic effect in human melanoma A375-S2 cells, this study was designed to further illustrate the molecular mechanisms underlying.

MATERIALS AND METHODS

Cell viability was evaluated in A375-S2 cells by MTT assay, and the mechanisms involved in physalin A-induced A375-S2 cell death were investigated by phase contrast microscopy and fluorescence microscopy, siRNA transfection, flow cytometry and western blot analysis.

RESULTS

We demonstrated that physalin A decreased the proportion of viable A375-S2 cells in a time- and dose-dependent manner, and exposure of A375-S2 cells to physalin A led to both apoptosis and autophagy. Moreover, physalin A-induced apoptosis was triggered by activation of p53-Noxa pathway and intracellular reactive oxygen species (ROS) generation. The administration of ROS scavengers NAC and GSH resulted in the complete inhibition of physalin A-induced ROS generation and apoptosis. Application of p53 inhibitor PFT-α or transfection with Noxa-siRNA could also lead to the same results. Autophagy, demonstrated by the punctuate distribution of monodansylcadaverine staining, as well as the change of LC3-II/LC3-I proportion and Beclin 1 activation, played a protective role against apoptosis via up-regulation of the p38-NF-κB survival pathway in A375-S2 cells. Additionally, inhibition of autophagy by the specific autophagic inhibitor 3MA or blocking the p38-NF-κB pathway with p38 inhibitor SB203580 or NF-κB inhibitor PDTC obviously promoted physalin A-induced apoptosis.

CONCLUSIONS

Physalin A induced apoptotic cell death via p53-Noxa-mediated ROS generation, and autophagy played a protective role against apoptosis through up-regulating the p38-NF-κB survival pathway in A375-S2 cells. These results stated the possibility that physalin A would be a potential agent for the treatment of melanoma in the future.

Physalin A induces apoptotic cell death and protective autophagy in HT1080 human fibrosarcoma cells

Physalin A (1) is a withanolide isolated from Physalis alkekengi var. franchetii. In this study, the selective growth inhibitory effects on tumor cells induced by 1 were screened, and the mechanism was investigated on 1-induced growth inhibition, including apoptosis and autophagy, in human fibrosarcoma HT1080 cells. Apoptosis induced by 1 in HT1080 cells was associated with up-regulation of caspase-3 and caspase-8 expression. However, there were no significant changes in caspase-9, Bid, Bax, and Bcl-2 expression, indicating that 1-induced apoptosis in HT1080 cells occurs mainly through activation of the death receptor-associated extrinsic apoptotic pathways. Autophagy induced by 1 was found to antagonize apoptosis in HT1080 cells. This effect was enhanced by rapamycin and suppressed by the autophagy inhibitor 3-methyladenine (3MA). Loss of beclin 1 (as an autophagic regulator) function led to similar results to 3MA. However, 1 did not show inhibitory effects on normal human cells (human peripheral blood mononuclear cells). Taken together, these results suggest that 1 may be a promising agent for the treatment of cancer.

Hydroxyl radical (·OH) played a pivotal role in oridonin-induced apoptosis and autophagy in human epidermoid carcinoma A431 cells

Oridonin, a diterpenoid compound extracted and purified from Rabdosia rubescen, has been reported to induce tumor cell apoptosis through tyrosine kinase pathway. To further examine the mechanism of oridonin, we selected human epidermoid carcinoma A431 cell as a test object. Besides apoptosis, oridonin also induced A431 cell autophagy, and this autophagy antagonized apoptosis and played a protective role for A431 cells. Reactive oxygen species (ROS) played a pivotal role in induction of cytotoxicity. Therefore, a ROS scavenger, N-acetylcysteine (NAC) combined with oridonin was appiled. Results of morphologic observation, flow cytometric analysis and Western blot analysis showed that NAC could significantly reverse both ROS generation and down-regulation of mitochondrial membrane potential in oridonin treated cells. NAC inhibited oridonin induced apoptosis through both the intrinsic and extrinsic apoptotic pathways. NAC effectively inhibited both oridonin-induced apoptosis and autophagy by reducing intracellular oxidative stress. To further examine the mechanism of ROS, exogenous enzyme antioxidants (superoxide dismutase (SOD), catalase (CAT)) and non-enzyme antioxidants (glutathione (GSH)) were applied to detect the effect of oridonin on ROS generation. Only GSH exerted a similar role with NAC, suggesting that hydroxyl radical (·OH) played the major role in oridonin-induced cell death. Oridonin could decrease the GSH level in A431 cells in a dose-dependent manner. In addition, after treatment with ·OH donor, Fenton reagent, the changes in A431cells were similar to the results of oridonin treatment. All the results proved that ·OH played the pivotal role in oridonin induced apoptosis and autophagy in A431 cells.

Autophagy induced by silibinin protects human epidermoid carcinoma A431 cells from UVB-induced apoptosis

Ultraviolet B (UVB) in the sun light is a major cause of skin damage, which accompanies complex alterations in irradiated skin cells, including DNA lesions, oxidative stress, inflammation and caspase activation. The protection against UVB damage requires multiple interruptions such as repair of the DNA lesions, scavenging of the reactive oxygen species (ROS), repression of the inflammation and others. Silibinin is suggested as an anti-UVB reagent, but the underlying mechanisms have not been fully elucidated. In this study, we found a role of autophagy in the anti-UVB effect of silibinin in A431 cells. Autophagy was reduced after UVB-irradiation while restored by silibinin through the suppression of the IGF-1R signalling pathway. The protective effect of silibinin in UVB-irradiated A431 cells was further enhanced by pre-treatment with an autophagy inducer, rapamycin, while it was reversed by an autophagy inhibitor, wortmannin, indicating that elevated autophagy contributed to the cell survival. Consistently, cell apoptosis was augmented by siRNAs targeting Beclin 1 and Atg5, supporting the hypothesis that autophagy induced by silibinin plays a protective role against UVB-induced epidermal apoptosis.