MiR-21 suppresses the anticancer activities of curcumin by targeting PTEN gene in human non-small cell lung cancer A549 cells

PURPOSE: Curcumin, a natural phytochemical, exhibits potent anticancer activities. Here, we sought to determine the molecular mechanisms underlying the cytotoxic effects of curcumin against human non-small cell lung cancer (NSCLC) cells. METHODS: MTT assay and annexin-V/PI staining were used to analyze the effects of curcumin on the proliferation and apoptosis of A549 cells. The expression of microRNA-21 in curcumin-treated A549 cells was measured by quantitative real-time polymerase chain reaction assay. The protein level of phosphatase and tensin homolog (PTEN), a putative target of microRNA-21, was determined by Western blot analysis. Transfection of A549 cells with microRNA-21 mimic or PTEN small interfering RNA was performed to modulate the expression of microRNA-21 and PTEN under the treatment of curcumin. RESULTS: Curcumin at 20-40 μM inhibited cell proliferation and induced apoptosis in A549 cells. Curcumin treatment produced a dose-dependent and significant (P < 0.05) suppression of microRNA-21 expression, compared to untreated A549 cells. Moreover, the protein level of PTEN, a putative target of microRNA-21, was significantly elevated in curcumin-treated A549 cells, as determined by Western blot analysis. Transfection of A549 cells with microRNA-21 mimic or PTEN small interfering RNA significantly (P < 0.05) reversed the growth suppression and apoptosis induction by curcumin, compared to corresponding controls. CONCLUSIONS: Our data suggest a novel molecular mechanism in which inhibition of microRNA-21 and upregulation of PTEN mediate the anticancer activities of curcumin in NSCLC cells. Suppression of microRNA-21 may thus have therapeutic benefits against this malignancy (AU)

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Functional identification of a novel F-box/FBA gene in tomato.

In plants and animals, the SCF-type ubiquitin protein ligases play an important role in many different physiological processes by regulating protein stability such as S-RNase-based self-compatibility, flower development, hormone responses and meiosis. This study identified an SlFbf gene in tomato that encodes 381 amino acid residues containing a typical F-box motif and an FBA_1 motif associated proteasome pathway; the transcripts of SlFbf was detected in all the tissues (root, stem, leaf, sepal, petal, stamen, pistil, green fruit, breaker fruit and red fruit), with the highest in stamen specifically during flowering stage; SlFbf responded to gibberellins, abscisic acid and light. Suppressed SlFbf leads to bigger pollen and less seeds showing that SlFbf might have an effect on fertilization through regulating stamen development. These findings provide more information about the functions of Fbf gene family.

Improvement of in vitro-transcribed amber suppressor tRNAs toward higher suppression efficiency in wheat germ extract.

In vitro-transcribed, unmodified, and non-aminoacylated amber suppressor tRNAs that are recognized by natural aminoacyl-tRNA synthetase were improved toward higher suppression efficiency in batch-mode cell-free translation in wheat germ extract. The suppression efficiency of the suppressor obtained through four sequence optimization steps (anticodon alteration of natural tRNAs (the first generation); chimerization of the efficient suppressors in the first generation; investigation and optimization of the effective parts in the second generation; combination of the optimized parts in the third generation) and by the terminal tuning was approximately 60%, which was 2.4-fold higher than that of the best suppressor in the first generation. In addition, an eRF1 aptamer further increased the efficiency up to 85%. This highly efficient suppression system also functioned well in a dialysis-based large-scale protein synthesis.

High-throughput screening of chemical libraries for modulators of gene promoter activity of HLA-B2705: environmental pathogenesis and therapeutics of ankylosing spondylitis.

OBJECTIVE: Ankylosing spondylitis (AS) is a highly heritable disease with HLA-B27 being the strongest susceptible gene. In order to survey the environmental triggers for arthritis development, we used a high-throughput technique to screen the effects of 12,264 chemicals on the HLA-B27 gene promoter. METHODS: Promoter reporter transfectants 293T-HLA-B27 and HeLa-HLA-B27 were tested using robotics with 12,264 chemicals. Chemicals that modulated HLA-B27 promoter activity > 150% or < 40% were selected for further evaluation of IC50/EC50 and cell viability. RESULTS: The primary screening using the 293T-HLA-B27 promoter reporter cell line yielded 5.1% hits that either suppressed (556 chemicals) or enhanced (68 chemicals) the HLA-B27 promoter activity. A secondary reconfirmation screening was carried out with these 624 candidates using HeLa-HLA-B27 promoter reporter cells under several different culture conditions. The yield of positive candidates was 130, of which 47 were derived from natural products. Based on the bio-information of those positive natural products, 21 chemicals were selected for analysis by dose-response IC50/EC50 experiments. Eight compounds showed potential pharmacological activities. Two suppressors are both derived from an herbal medicine (lei gong teng) that has been used for decades to treat immune diseases. The 6 activators all belonged to a group of chemicals known as flavonoids, widely distributed among dietary fruits and vegetables. CONCLUSION: Several common dietary products that contain certain flavonoids might be environmental risk factors for AS; the Chinese traditional herb lei gong teng might be a potential drug for patients who are HLA-B27-positive. These results provide new research directions for the pathogenesis and therapeutics of AS.

A Drosophila model of Menkes disease reveals a role for DmATP7 in copper absorption and neurodevelopment.

Human Menkes disease is a lethal neurodegenerative disorder of copper metabolism that is caused by mutations in the ATP7A copper-transporting gene. In the present study, we attempted to construct a Drosophila model of Menkes disease by RNA interference (RNAi)-induced silencing of DmATP7, the Drosophila orthologue of mammalian ATP7A, in the digestive tract. Here, we show that a lowered level of DmATP7 mRNA in the digestive tract results in a reduced copper content in the head and the rest of the body of surviving adults, presumably owing to copper entrapment in the gut. Similar to Menkes patients, a majority of flies exhibit an impaired neurological development during metamorphosis and die before eclosion. In addition, we show that survival to the adult stage is highly dependent on the copper content of the food and that overexpression of the copper homeostasis gene, metal-responsive transcription factor-1 (MTF-1), enhances survival to the adulthood stage. Taken together, these results highlight the role of DmATP7-mediated copper uptake in the neurodevelopment of Drosophila melanogaster and provide a framework for the analysis of potential gene interactions influencing Menkes disease.