RESUMO
In Saccharomyces cerevisiae, conventional 2µ-plasmid based plasmid (pC2µ, such as pRS425) have been widely adopted in pathway engineering for multi-copy overexpression of key genes. However, the loss of partition and copy number control elements of yeast endogenous 2µ plasmid (pE2µ) brings the issues concerning plasmid stability and copy number of pC2µ, especially in long-term fermentation. In this study, we developed a method based on CRISPR/Cas9 to edit pE2µ and built the pE2µ multi-copy system by insertion of the target DNA element and elimination of the original pE2µ plasmid. The resulting plasmid pE2µRAF1 and pE2µREP2 demonstrated higher copy number and slower loss rate than a pC2µ control plasmid pRS425RK, when carrying the same target gene. Then, moving the essential gene TPI1 (encoding triose phosphate isomerase) from chromosome to pE2µRAF1 could increase the plasmid viability to nearly 100% and further increase the plasmid copy number by 73.95%. The expression using pE2µ multi-copy system demonstrated much smaller cell-to-cell variation comparing with pC2µ multi-copy system. With auxotrophic complementation of TPI1, the resulting plasmid pE2µRT could undergo cultivation of 90 generations under non-selective conditions without loss. Applying pE2µ multi-copy system for dihydroartemisinic acid (DHAA) biosynthesis, the production of DHAA was increased to 620.9 mg/L at shake-flask level in non-selective rich medium. This titer was 4.73-fold of the strain constructed based on pC2µ due to the more stable pE2µ plasmid system and with higher plasmid copy number. This study provides an improved expression system in yeast, and set a promising platform to construct biosynthesis pathway for valuable products.
RESUMO
Magnolol and honokiol are the two major active ingredients with similar structure and anticancer activity from traditional Chinese medicine Magnolia officinalis, and honokiol is now in a phase I clinical trial (CTR20170822) for advanced non-small cell lung cancer (NSCLC). In search of potent lead compounds with better activity, our previous study has demonstrated that magnolol derivative C2, 3-(4-aminopiperidin-1-yl)methyl magnolol, has better activity than honokiol. Here, based on the core of 3-(4-aminopiperidin-1-yl)methyl magnolol, we synthesized fifty-one magnolol derivatives. Among them, compound 30 exhibited the most potent antiproliferative activities on H460, HCC827, H1975 cell lines with the IC50 values of 0.63-0.93 µM, which were approximately 10- and 100-fold more potent than those of C2 and magnolol, respectively. Besides, oral administration of 30 and C2 on an H460 xenograft model also demonstrated that 30 has better activity than C2. Mechanism study revealed that 30 induced G0/G1 phase cell cycle arrest, apoptosis and autophagy in cancer cells. Moreover, blocking autophagy by the autophagic inhibitor enhanced the anticancer activity of 30in vitro and in vivo, suggesting autophagy played a cytoprotective role on 30-induced cancer cell death. Taken together, our study implied that compound 30 combined with autophagic inhibitor could be another choice for NSCLC treatment in further investigation.