ATM pathway is essential for ionizing radiation-induced autophagy

BackgroundATM plays an important role in response to DNA damage, while the roles of ATM in radiation-induced autophagy are still unclear in cervical cancer cells.MethodsHuman cervical cancer cells, Hela, were used, and cell models with ATM^?/? and MAPK14^?/? were established by gene engineering. Western blot was implemented to detect protein expression. MDC staining and GFP-LC3 relocalization were used to detect autophagy. CCK-8 was used to detect cell viability. Radiosensitivity was analyzed by colony formation assays. Co-immunoprecipitation was used to detect the interaction between different proteins, and apoptosis was detected by flow cytometry.ResultsAfter radiation autophagy was induced, illustrated by the increase of MAPLC3-II/MAPLC3-I ratio and decrease of p62, and phosphorylation of ATM simultaneously increased. ATM^?/? cells displayed hypersensitivity but had no influence on IR-induced apoptosis. Then inhibitor of ATM, KU55933, ATM and MAPK14 silencing were used, and autophagy was induced by IR more than 200% in control, and only by 35.72%, 53.18% and 24.76% in KU55933-treated cells, ATM^?/? and MAPK14^?/? cells, respectively. KU55933 inhibited IR-induced autophagy by activating mTOR pathways. ATM silencing decreased the expression of MAPK14 and mTOR signals significantly. Beclin's bond to PI3KIII and their interaction increased after IR, while in ATM^?/? and MAPK14^?/? cells this interaction decreased after IR. Both ATM and MAPK14 interacted with Beclin, while ATM^?/? and MAPK14^?/? cells showed no interaction.ConclusionsATM could promote IR-induced autophagy via the MAPK14 pathway, the mTOR pathway, and Beclin/PI3KIII complexes, which contributed to the effect of ATM on radiosensitivity.     

生物活性肽

生物活性肽是对生物机体的生命活动有益或具有生理作用的肽类化合物,简述了生物活性肽的分类、特点、作用机理以及开发应用。     

Targeting bone remodeling by isoflavone and 3,3'-diindolylmethane in the context of prostate cancer bone metastasis

Prostate cancer (PCa) bone metastases have long been believed to be osteoblastic because of bone remodeling leading to the formation of new bone. However, recent studies have shown increased osteolytic activity in the beginning stages of PCa bone metastases, suggesting that targeting both osteolytic and osteoblastic mediators would likely inhibit bone remodeling and PCa bone metastasis. In this study, we found that PCa cells could stimulate differentiation of osteoclasts and osteoblasts through the up-regulation of RANKL, RUNX2 and osteopontin, promoting bone remodeling. Interestingly, we found that formulated isoflavone and 3,3'-diindolylmethane (BR-DIM) were able to inhibit the differentiation of osteoclasts and osteoblasts through the inhibition of cell signal transduction in RANKL, osteoblastic, and PCa cell signaling. Moreover, we found that isoflavone and BR-DIM down-regulated the expression of miR-92a, which is known to be associated with RANKL signaling, EMT and cancer progression. By pathway and network analysis, we also observed the regulatory effects of isoflavone and BR-DIM on multiple signaling pathways such as AR/PSA, NKX3-1/Akt/p27, MITF, etc. Therefore, isoflavone and BR-DIM with their multi-targeted effects could be useful for the prevention of PCa progression, especially by attenuating bone metastasis mechanisms.     

Inactivation of uPA and its receptor uPAR by 3,3′‐diindolylmethane (DIM) leads to the inhibition of prostate cancer cell growth and migration

3,3′‐Diindolylmethane (DIM) has been studied for its putative anti‐cancer properties, especially against prostate cancer; however, its exact mechanism of action remains unclear. We recently provided preliminary data suggesting down‐regulation of uPA during B‐DIM (a clinically active DIM)‐induced inhibition of invasion and angiogenesis in prostate cancer cells. Since the expression and activation of uPA plays important role in tumorigenicity, and high endogenous levels of uPA and uPAR are found in advanced metastatic cancers, we investigated their role in B‐DIM‐mediated inhibition of prostate cancer cell growth and motility. Using PC3 cells, we found that B‐DIM treatment as well as the silencing of uPA and uPAR by siRNAs led to the inhibition of cell growth and motility. Conversely, over‐expression of uPA/uPAR in LNCaP and C4‐2B cells resulted in increased cell growth and motility, which was effectively inhibited by B‐DIM. Moreover, we found that uPA as well as uPAR induced the production of VEGF and MMP‐9, and that the down‐regulation of uPA/uPAR by siRNAs or B‐DIM treatment resulted in the inhibition of VEGF and MMP‐9 secretion which could be responsible for the observed inhibition of cell migration. Interestingly, silencing of uPA/uPAR led to decreased sensitivity to B‐DIM indicating important role of uPA/uPAR in B‐DIM‐mediated regulation of prostate cancer cell growth and migration. Our data suggest that chemopreventive and/or therapeutic activity of B‐DIM is in part due to down‐regulation of uPA–uPAR leading to reduced production of VEGF/MMP‐9 which ultimately leads to the inhibition of cell growth and migration of aggressive prostate cancer cells. J. Cell. Biochem. 107: 516–527, 2009. © 2009 Wiley‐Liss, Inc.     

The flexible interrelation between AOX respiratory pathway and photosynthesis in rice leaves.

Alternative respiratory pathway was investigated in rice seedlings grown under total darkness, light/dark cycle, or continuous light. The capacity of the alternative pathway was relatively higher in leaves that had longer light exposure. An analysis of rice AOX1 multigene family revealed that AOX1c, but not AOX1a and AOX1b, had a light-independent expression. The alternative oxidase (AOX) inhibitor, salicylhydroxamic acid (SHAM, 1mM), inhibited nearly 68% of the capacity of the alternative pathway in leaves grown under different light conditions. The plants grown under different light periods were treated with SHAM and then were exposed to illumination for 4h. The transition from dark to 4h of light stimulated the capacity of alternative pathway in etiolated rice seedlings and in those grown under light/dark cycle, whereas the capacity of the alternative pathway was constant in seedlings grown under continuous light with additional 4h of illumination. Etiolated leaves did not show any CO(2) fixation after 4h of illumination, and the increase in chlorophyll content was delayed by the SHAM pretreatment. When seedlings grown under light/dark cycle were moved from dark and exposed to 4h of light, increases in chlorophyll content and CO(2) fixation rate were reduced by SHAM. Although these parameters were stable in plants grown under continuous light, SHAM decreased CO(2) fixation rate but not the chlorophyll content. These results indicate that the role and regulation of AOX in light are determined by the developmental stage of plant photosynthetic apparatus.     

Quorum-sensing system in Acidithiobacillus ferrooxidans involved in its resistance to Cu²⁺

Aims: The purpose of this study was to search for the relationship between quorum sensing (QS) and Cu²⁺ resistance in Acidithiobacillus ferrooxidans. Methods and Results: Resistance to Cu²⁺ of A. ferrooxidans significantly decreased with the treatment dose of a synthetic QS blocker (5Z)‐4‐bromo‐5‐(bromomethylene)‐2(5H)‐furanone (FUR). Relative differences in expression of the QS genes afeI, afeR and Cu²⁺ resistance‐associated genes afe0329, afe0454 were examined in the presence of Cu²⁺ and/or FUR compound. The expression of QS genes afeI and afeR increased significantly with 50 mmol l^?1 Cu²⁺ in the culture, while for samples treated with both 50 mmol l^?1 Cu²⁺ and 0·01 μg ml^?1 FUR compound, they showed little changes compared with control, and the expression of afe0329 and afe0454 genes increased slightly either. These results showed that QS system was positively related to the mechanism of Cu²⁺ resistance. Conclusions: QS system in A. ferrooxidans involved in its resistance to Cu^2+. Significance and Impact of the Study: The mechanisms of Cu²⁺ resistance in A. ferrooxidans could be revealed on a population level rather than on a single‐cell level. Our work also provides useful data for further selection of A. ferrooxidans strains with suitable Cu²⁺ resistance that could probably increase the bioleaching efficiency.     

Attenuation of multi-targeted proliferation-linked signaling by 3,3'-diindolylmethane (DIM): from bench to clinic

Emerging evidence provide credible support in favor of the potential role of bioactive products derived from ingesting cruciferous vegetables such as broccoli, brussel sprouts, cauliflower and cabbage. Among many compounds, 3,3'-diindolylmethane (DIM) is generated in the acidic environment of the stomach following dimerization of indole-3-carbinol (I3C) monomers present in these classes of vegetables. Both I3C and DIM have been investigated for their use in preventing, inhibiting, and reversing the progression of cancer - as a chemopreventive agent. In this review, we summarize an updated, wide-ranging pleiotropic anti-tumor and biological effects elicited by DIM against tumor cells. It is unfeasible to point one single target as basis of cellular target of action of DIM. We emphasize key cellular and molecular events that are effectively modulated in the direction of inducing apoptosis and suppressing cell proliferation. Collectively, DIM orchestrates signaling through Ah receptor, NF-κB/Wnt/Akt/mTOR pathways impinging on cell cycle arrest, modulation of key cytochrome P450 enzymes, altering angiogenesis, invasion, metastasis and epigenetic behavior of cancer cells. The ability of DIM to selectively induce tumor cells to undergo apoptosis has been observed in preclinical models, and thus it has been speculated in improving the therapeutic efficacy of other anticancer agents that have diverse molecular targets. Consequently, DIM has moved through preclinical development into Phase I clinical trials, thereby suggesting that DIM could be a promising and novel agent either alone or as an adjunct to conventional therapeutics such as chemo-radio and targeted therapies. An important development has been the availability of DIM formulation with superior bioavailability for humans. Therefore, DIM appears to be a promising chemopreventive agent or chemo-radio-sensitizer for the prevention of tumor recurrence and/or for the treatment of human malignancies.