RESUMEN
The development of innovative methods for highly efficient production of recombinant proteins remains a prominent focus of research in the biotechnology field, primarily due to the fact that current commercial protein expression systems rely on expensive chemical inducers, such as isopropyl ß-D-thiogalactoside (IPTG). In our study, we designed a novel approach for protein expression by creating a plasmid that responds to copper. This specialized plasmid was engineered through the fusion of a copper-sensing element with an optimized multiple cloning site (MCS) sequence. This MCS sequence can be easily customized by inserting the coding sequences of target recombinant proteins. Once the plasmid was generated, it was introduced into an engineered Escherichia coli strain lacking copA and cueO. With this modified E. coli strain, we demonstrated that the presence of copper ions can efficiently trigger the induction of recombinant protein expression, resulting in the production of active proteins. Most importantly, this expression system can directly utilize copper-containing industrial wastewater as an inducer for protein expression while simultaneously removing copper from the wastewater. Thus, this study provides a low-cost and eco-friendly strategy for the large-scale recombinant protein production. To the best of our knowledge, this is the first report on the induction of recombinant proteins using industrial wastewater.
RESUMEN
Over the past few years, the antitumor activity exhibited by 5-caffeylquinic acid (5-CQA), especially its inhibitory effect on hepatocellular carcinoma (HCC) proliferation and metastasis, has been recognized as a new research hotspot. However, impacted by the weak antitumor toxicity of 5-CQA, its clinical application has been limited. In this study, the antitumor effect arising from 5-CQA on HCC cells was evaluated through cell viability assay. In addition, proteomics, flow cytometry, qRT-PCR and western blotting were adopted to investigate the drug resistance mechanism of HCC cells to 5-CQA. As indicated by the results, 5-CQA significantly inhibited the proliferation of HCC cell lines MHCC97H and HCCLM3 with IC5048 h of 546.8 µM and 452 µM, respectively. According to the in-depth studies, the abnormal activation of HIF-1α/glucose transporters/glycolysis pathway of 5-CQA could be a key molecular mechanism leading to drug resistance of HCC cells. Thus, this study found that glucose starvation, glucose analogue 2-DG, hexokinase inhibitor bromopyruvic acid and PKM2 inhibitor compound 3k inhibited HCC cell proliferation in synergy with 5-CQA. Furthermore, though the 5-CQA derivatives methyl chlorogenate (MCGA) and 3,5-dicaffeoylquinic acid (3,5-diCQA) exhibited more potent antiproliferation activity in HCC cells than 5-CQA, they also up-regulated the expression of GLUT1/3, whereas they had no effect on hepatocytes. To be specific, under low-glucose culture conditions, the order of sensitivity of HCC cells to CQAs was 3,5-diCQA > MCGA > 5-CQA. In brief, the above results revealed that intervention in glucose metabolism can facilitate the effects of 5-CQA and its derivatives for treating HCC.
