Molecular response mechanism in Escherichia coli under hexabromocyclododecane stress.

The effects of hexabromocyclododecane (HBCD) on the relationship between physiological responses and metabolic networks remains unclear. To this end, cellular growth, apoptosis, reactive oxygen species, exometabolites and the proteome of Escherichia coli were investigated following exposure to 0.1 and 1 µM HBCD. The results showed that although there were no significant changes in the pH value, apoptosis and reactive oxygen species under HBCD stress, cell growth was inhibited. The metabolic network formed by glycolysis, oxidative phosphorylation, amino acids biosynthesis, membrane proteins biosynthesis, ABC transporters, glycogen storage, cell recognition, compound transport and nucleotide excision repair was disrupted. Cell chemotaxis and DNA damage repair were the effective approaches to alleviate HBCD stress. This work improves our understanding of HBCD toxicity and provides insight into the toxicological mechanism of HBCD at the molecular and network levels.

Inhibitor of apoptosis protein­like protein­2: A novel growth accelerator for breast cancer cells.

Although the inhibitor of apoptosis protein­like protein­2 (ILP­2) has been shown as a serological biomarker for breast cancer, its effect on breast cancer cell growth remains elusive. The present study aimed to determine the role of ILP­2 in breast cancer cell growth. We used immunohistochemistry to analyze ILP­2 expression in 59 tissue paraffin­embedded blocks, which included 35 breast cancer tissues and 24 galactophore hyperplasia tissues. Western blot analysis was used to detect protein expression levels of ILP­2 in breast cancer cell lines such as HCC­1937, MX­1 and MCF­7 as well as breast gland cell line MCF 10A. ILP­2 was silenced by siRNA in HCC­1937, MX­1 and MCF­7 cell lines. MTT assays, scratch assays and AO­EB double staining analysis were conducted to evidence the role of ILP­2 on breast cancer cell growth. Results from this study showed increased ILP­2 expression in breast cancer tissues and breast cancer cell lines such as HCC­1937, MX­1 and MCF­7. Cell viability or rate of cell migration of HCC­1937, MX­1 and MCF­7 cell lines was significantly inhibited when ILP­2 was knocked down by siRNA. The apoptosis rate of HCC­1937, MX­1 and MCF­7 cell lines was increased when compared with that of the control group. Thus, ILP­2 plays an active role in the growth of breast cancer cells.

Triphenyltin degradation and proteomic response by an engineered Escherichia coli expressing cytochrome P450 enzyme.

Although triphenyltin (TPT) degradation pathway has been determined, information about the enzyme and protein networks involved was severely limited. To this end, a cytochrome P450 hydroxylase (CYP450) gene from Bacillus thuringiensis was cloned and expressed in Escherichia coli BL21 (DE3), namely E. coli pET32a-CYP450, whose dosage at 1gL-1 could degrade 54.6% TPT at 1mgL-1 within 6 d through attacking the carbon-tin bonds of TPT by CYP450. Sequence analysis verified that the CYP450 gene had a 1214bp open reading frame, encoding a protein with 404 amino acids. Proteomic analysis determined that 60 proteins were significantly differentially regulated expression in E. coli pET32a-CYP450 after TPT degradation. The up-regulated proteins enriched in a network related to transport, cell division, biosynthesis of amino acids and secondary metabolites, and microbial metabolism in diverse environments. The current findings demonstrated for the first time that P450 received electrons transferring from NADH could effectively cleave carbon-metal bonds.