جستجوی مقالات مرتبط با کلیدواژه « thermal resistance » در نشریات گروه « پزشکی »

 The production of recombinant human growth hormone is usually problematic in Escherichia coli, and achieving higher functional protein yields is economically important.

 In this study, the chromosomal expression of recombinant human growth hormone (hGH) in the araBAD operon was investigated using Rosetta-gami and BL21 (DE3) competent cells under the regulation of arabinose and T7 promoters using arabinose inducer and IPTG, respectively. Subsequently, the expression of the plasmid-based protein was examined using pET28 (a) + plasmid in Rosetta-gami under the T7 promoter, and the results were compared.

 The lambda red technique was used to integrate the desired gene into the host genome. The Fh8 tag was used to increase the protein’s expression, solubility, and thermal resistance.

 The recombinant BL21 (DE3) under the T7 promoter and the recombinant Rosetta-gami containing pET28-Fh8-hGH plasmid showed significant expression among the chromosome-based and plasmid-based strains, respectively. Preliminary studies on the solubility and thermal resistance of the produced proteins indicated the efficacy of the Fh8 tag in increasing the expression, solubility, and thermal resistance of the product.

 One advantage of the genomic expression approach is the stability of the gene in the genome. Also, the lack of the need to use antibiotics in production systems can effectively reduce the production costs of this widely used hormone. In addition, the presence of the Fh8 tag can facilitate and accelerate its purification process by increasing the heat resistance thermostability of growth hormone.

The purpose of this study was to investigate the enhanced thermal resistance mechanism of the DU145 tumor spheroid cultures as compared to the prostate carcinoma cell line's monolayer cultures. DU145 cells were cultured either as spheroids or monolayers. Cultures were treated with hyperthermia in a precision water bath (at 43°C for 60 minutes) and/or quercetin (50 and 500 μM for monolayer and spheroid cultures respectively). After hyperthermic treatment, the cell viability colony forming ability, and the expression of heat shock protein 70 (Hsp70) were examined in both culture systems. Hsp70 expression was studied using the western blot method. Our results showed that the DU145 monolayer and spheroid cell culture treatment with hyperthermia alone resulted in a marked survival inhibition. Furthermore, the spheroids showed a more significant resistance to hyperthermia compared to the monolayer cultures (p = 0.01). They also produced more Hsp70 than the monolayer cultures. Treatment of cells with quercetin reduced the Hsp70 level in both culture systems. However, with the reduced Hsp70 levels, thermal resistance of the spheroids showed a greater decrease in relation to that of the monolayers. The results suggest that the enhanced hyperthermia resistance mechanism of the spheroid cultures compared to that of the monolayer cultures can be attributed to spheroid's Hsp70 production.