RESUMEN
AIM OF THE STUDY: To explore the mechanism of oxidative stress in the development of prostate cancer, here we compared 4-hydroxynonenal (4-HNE)- treated LNCaP (hormone-sensitive) and DU145 (hormone insensitive) cells with significant differences in sensitivity to androgen. MATERIAL AND METHODS: The prostate cancer cell line LNCaP and late cell line DU145 were treated with different concentrations of 4-HNE. The cell proliferation, apoptosis and mitochondrial transmembrane potential were detected at different time points, and expression of related molecules in cell proliferation and apoptosis signal pathway was analyzed by Western blot, and the over-expression of glutathione S-transferase (GSTA-4) was used to validate the changes of the effects of 4-HNE on the two kinds of cells. RESULTS: LNCaP cells showed greater antiproliferative and proapoptotic activities of HNE in a time- and dose-dependent manner corresponding to the activation of p53-mediated intrinsic apoptotic signaling, but JNK activation was not observed. In contrast, HNE-treated DU145 cells showed less apoptosis and proliferation was not inhibited; instead there was sustained activation of JNK, but activation of p53, p-p53, p21, Bax and caspase-3 was not observed. In addition, their effect of induction of apoptosis can be inhibited by overexpression of GSTA-4. CONCLUSIONS: These studies suggest that 4-HNE promotes prostate cancer cell apoptosis through the p53 signaling pathway; the differences of sensitivity to 4-HNE in LNCaP and DU145 cells may be related to the androgen sensitivity of prostate cancer cells; and the 4-HNE-induced p53-mediated apoptosis signal is regulated by GSTA-4.
RESUMEN
The xylanolytic enzymes found in Thermotoga maritima showed extremely high thermostability and considerable potential in industrial application. Yet expression level of the genes encoding these enzymes was very low. The alpha-glucuronidase gene aguA from T. maritima ATCC 43589 was cloned and expressed in several E. coli strains with different vector. The alpha-glucuronidase was overexpressed in E. coli BL21-CodonPlus(DE3)-RIL with plasmid pET-28a(+), and made up about 20% of the total proteins present in the intracellular soluble fraction. The results proved the assumption that rare codons for arginine (AGA/AGG) and isoleucine (AUA) affect the expression of aguA gene from hyperthermophilic bacterium T. maritima in E. coli. Purification procedure included two steps, heat treatment and immobilized metal affinity chromatography, and over 13.5mg of pure enzyme was obrained from 1L of induced culture. The purified enzyme showed a single band on SDS polyacrylamide gel electrophoresis with a purification of 5.1 fold, and a yield of 55.1%. The optimum activity of recombinant alpha-glucuronidase was found at pH 6.0 and 85 degrees C, the enzyme retained 70% of its activity after 1 h of incubation at 85 degrees C. The induction conditions for expression of recombinant strain BL21-CodonPlus(DE3)-RIL/pET-28a-aguA were studied on induction time and duration by IPTG. The results showed that the activity of thermostable alpha-glucuronidase reach the maximum in 5-hour after inducted at the exponential phase (OD600 of 0.7 - 0.8).
