The flavohaemoprotein hmp maintains redox homeostasis in response to reactive oxygen and nitrogen species in Corynebacterium glutamicum.

BACKGROUND: During the production of L-arginine through high dissolved oxygen and nitrogen supply fermentation, the industrial workhorse Corynebacterium glutamicum is exposed to oxidative stress. This generates reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are harmful to the bacteria. To address the issue and to maintain redox homeostasis during fermentation, the flavohaemoprotein (Hmp) was employed. RESULTS: The results showed that the overexpression of Hmp led to a decrease in ROS and RNS content by 9.4% and 22.7%, respectively, and improved the survivability of strains. When the strains were treated with H2O2 and NaNO2, the RT-qPCR analysis indicated an up-regulation of ammonium absorption and transporter genes amtB and glnD. Conversely, the deletion of hmp gives rise to the up-regulation of eight oxidative stress-related genes. These findings suggested that hmp is associated with oxidative stress and intracellular nitrogen metabolism genes. Finally, we released the inhibitory effect of ArnR on hmp. The Cc-ΔarnR-hmp strain produced 48.4 g/L L-arginine during batch-feeding fermentation, 34.3% higher than the original strain. CONCLUSIONS: This report revealed the influence of dissolved oxygen and nitrogen concentration on reactive species of Corynebacterium glutamicum and the role of the Hmp in coping with oxidative stress. The Hmp first demonstrates related to redox homeostasis and nitrite metabolism, providing a feasible strategy for improving the robustness of strains.

Formation of free radicals in Chi-aroma Baijiu during aging process with fat pork.

Soaking aged fat pork is a special aging process in the production of Chi-aroma Baijiu considered to involve the formation of free radicals. This study aimed to investigate the free radicals' formation pathway in Chi-aroma Baijiu during aged fat pork soaking by using electron paramagnetic resonance (EPR) and spin trapping with 5,5-dimethyl-1-pyrrolin-n-oxide (DMPO). The alkyl radical adducts (DMPO-R) and hydroxyl radical adducts (DMPO-OH) were detected in Baijiu after soaking the fat pork for aging. During the preparation process of aged fat pork, alkoxy radicals adduct (DMPO-RO) were mainly detected since lipid oxidation. Oleic acid and linoleic acid, the two main unsaturated fatty acids in fat pork, produced alkoxy radicals in the oxidation process. The total amounts of spins in linoleic acid and oleic acid after 4-month oxidation treatment increased by 248.07 ± 26.65% and 34.17 ± 0.72% than 0-month. It indicated that the free radicals in aged Chi-aroma Baijiu were mainly derived from the two main unsaturated fatty acids in aged fat pork and linoleic acid had a stronger ability to produce free radicals than oleic acid. Alkoxy radicals (RO·) from fat pork reacted with ethanol in Baijiu to form alkyl radicals (R·). The peroxide bond of hydroperoxides from the oxidation of unsaturated fatty acid was cleaved to form hydroxyl radicals (·OH) that were transferred to Baijiu. The results provide theoretical guidance for the subsequent work of free radicals scavenging.

The complete chloroplast genome of Leptochilus hemionitideus, a traditional Chinese medical fern.

The complete chloroplast genome of Leptochilus hemionitideus was sequenced. Its length is 156,083 bp with 44.2% GC content. The genome exhibits typical quadripartite with two inverted repeat regions (24,594 bp, each) separated by a large single-copy (LSC, 81,403 bp) region and a small single-copy (SSC, 25,492 bp) region. It has 131 genes, including 87 protein-coding genes, 34 tRNA genes, eight rRNA genes and two pseudogenes. Maximum-likelihood phylogenetic tree indicated that L. hemionitideus was closely related to Lepisorus clathratus. The complete chloroplast genome of L. hemionitideus would provide very valuable molecular information for further inferring the relationships of the microsoroid ferns.

Epidermal growth factor receptor inhibitor (PD168393) potentiates cytotoxic effects of paclitaxel against androgen-independent prostate cancer cells.

Recent data showed that epidermal growth factor receptor (EGFR) inhibitors, such as ZD1839, alone or in combination with chemotherapeutic agents for androgen-independent prostate cancer (AIPC) did not produce promising results in clinical settings. More effective regimens involving novel stronger inhibitor of EGFR and better combinations are needed. The anti-tumor activity of PD168393, an irreversible EGFR inhibitor, with or without chemotherapeutic agents for the treatment of AIPC was investigated in vitro. In results, both the androgen-independent cell lines PC-3 and DU145 expressed higher levels of EGFR than the androgen-dependent MDA PCa 2b and androgen-responsive LNCaP cells by Western blotting. DU145 was much more sensitive to PD168393 and ZD1839 than MDA PCa 2b. PD168393, but not ZD1839, significantly potentiated paclitaxel cytotoxicity against DU145 by MTT assay and median-effect analysis. The combination of PD168393 or ZD1839 with other cytotoxic agents including docetaxel and 5-fluorouracil, however, was either additive or antagonistic. Compared to paclitaxel alone, PD168393 significantly enhanced paclitaxel-induced DNA fragmentation, sub-G1 fraction accumulation, mitochondrial membrane dysfunction, cytochrome C release, caspase-3 activation and eventually apoptosis. These molecular events were accompanied by Bad up-regulation, p53 and p21Waf1/Cip1 induction, ERK1/2 inactivation and inhibition of EGFR phosphorylation in the presence of PD168393. These effects did not involve significant alteration in the Akt1/2 and STAT3 signaling pathway. In conclusion, the combination of paclitaxel and PD168393 produced a profound synergistic growth inhibition of AIPC cells. Combining PD168393 with paclitaxel may have clinical benefits and warrants further investigation.

Characterization of molecular events in a series of bladder urothelial carcinoma cell lines with progressive resistance to arsenic trioxide.

Our previous studies have shown that arsenic trioxide (As2O3), a novel anti-cancer agent, may be active against urothelial carcinomas. A series of bladder urothelial carcinoma cells with progressive As2O3 resistance were established and studied to reveal molecular events in relation to the mechanisms of resistance to As2O3. A sensitive parental line (NTUB1) and three As2O3-resistant sublines (NTUB1/As) were used with their IC50s being 0.9, 1.2, 2.5 and 4.9 microM, respectively. Cellular resistance to As2O3 was associated with a lowered proliferation profile (increased p53 and p21Waf1/Cip1 and decreased c-Myc levels) and a greater resistance to apoptosis (elevated Bcl-2 levels). Cells with a stronger resistance had higher expressions of superoxide dismutase (Cu/Zn) and hMSH2 (but not hMLH1). GSH contents were up-regulated in resistant cells in a dose-dependent manner. The DNA-binding activities of NF-kappaB and AP-1 were down-regulated in resistant cells in a dose-dependent manner. Profound molecular alterations occur during the acquisition of secondary As2O3 resistance. Our in vitro cellular model may help to reveal resistance mechanisms to As2O3 in bladder urothelial carcinoma cells.

Cytotoxicity of arsenic trioxide to transitional carcinoma cells.

OBJECTIVES: To explore the therapeutic efficacy of arsenic trioxide (As2O3) in human transitional cell carcinomas, we investigated the potential use of the compound as a chemotherapeutic agent and the possible cross-resistance with cisplatin in this malignancy. METHODS: Three bladder transitional carcinoma cell lines, NTUB1, NTUB1/P (cisplatin-resistant), and NTUB1/As (As2O3-resistant), were used. The chemosensitivity of the three cell lines to cisplatin and As2O3 was determined by the microculture tetrazolium assay. The modulatory effect of buthionine sulfoximine (BSO) on As2O3 cytotoxicity was studied by combining the two agents simultaneously or sequentially and evaluated using the median-effect analysis. Cellular glutathione contents were determined using a biochemical method. RESULTS: There was evident cross-resistance between cisplatin and As2O3 in the cell model used. BSO significantly enhanced As2O3 cytotoxicity in the three cell lines, indicating synergism in combination. In the presence of 3 microM BSO, the sensitivity of NTUB1, NTUB1/P, and NTUB1/As to As2O3 was increased 3, 7.4, and 8.4-fold, respectively. Among the three different combination schedules, greater cytotoxic effects were obtained by concurrent exposure to both agents. A significant dose-response relationship was found between the BSO concentrations and glutathione contents in NTUB1 (P = 0.007) and NTUB1/As (P = 0.05) but not NTUB1/P (P = 0.1) cells. CONCLUSIONS: As2O3 in the presence of BSO may be an active agent against transitional cell carcinoma. Our results have clinical implications and warrant further investigation.

Arsenic trioxide as a novel anticancer agent against human transitional carcinoma--characterizing its apoptotic pathway.

Arsenic trioxide (As(2)O(3)) has been shown to be an active agent against acute promyelocytic leukemia. Little is known about its therapeutic efficacy in human transitional carcinomas. In this study, the arsenic-mediated apoptotic pathway in transitional carcinoma cells was investigated. Three bladder transitional carcinoma cell lines were used, including a parental sensitive line and two resistant daughter lines (cisplatin and As(2)O(3) resistant). The As(2)O(3)-mediated cytotoxicity to the three cell lines was studied in vitro in the presence or absence of buthionine sulfoximine (BSO), a chemotherapy modulator. In results, although a lesser extent of apoptosis was seen in cells treated with As(2)O(3) alone, more significant apoptotic events were observed in the combined treatment of As(2)O(3) and non-toxic concentrations of BSO (up to 10 microM). These included the accumulation of sub-G(1) fractions and internucleosomal DNA breakdown, which were preceded by production of reactive oxygen species, loss of mitochondrial membrane potential and activation of caspase-3. In conclusion, As(2)O(3) in the presence of BSO may be an active agent against both chemonaive and cisplatin-resistant transitional carcinomas. The As(2)O(3)-mediated cytotoxicity appeared to go through the conventional apoptotic pathway. Our results have clinical implications and warrant further investigation.

Curcumin enhances cytotoxicity of chemotherapeutic agents in prostate cancer cells by inducing p21(WAF1/CIP1) and C/EBPbeta expressions and suppressing NF-kappaB activation.

BACKGROUND: The modulatory effects and molecular mechanisms of curcumin (CCM) on the cytotoxicity of chemotherapeutic agents to prostate cancer cells were explored. METHODS: The combined effects of CCM and chemotherapeutic agents were examined by three different administration schedules (one concurrent and two sequential treatments) in two androgen-independent prostate cancer (AIPC) cells (PC-3 and DU145). Alteration of cell cycle progression, protein levels, and transcriptional activation in PC-3 cells were assayed by flow cytometry, Western blotting, and gel shift assay, respectively. RESULTS: The combined effects of CCM --> chemotherapeutic agent schedule showed the greatest synergistic cytotoxicity when compared to the other two schedules in both cells. CCM induced a significant G1 arrest in PC-3, which may be mediated by the induction of p21(WAF1/CIP1) and C/EBPbeta. Moreover, CCM was able to inhibit both the constitutional and TNF-alpha-induced NF-kappaB activation in a time-dependent manner. CONCLUSIONS: The incorporation of CCM into cytotoxic therapies may be a promising strategy for the treatment of AIPC.