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Zhang P.,Peking Union Medical College | Sun M.,Peking Union Medical College | Sun M.,Chinese Academy of Sciences | Qiu R.,Beijing Biostar Technologies Ltd. | And 3 more authors.
Cancer Chemotherapy and Pharmacology | Year: 2011

Purpose: The epothilones are a novel class of microtubule-stabilizing agents. UTD1 is an epothilone analog generated by genetic manipulation of the polyketide biosynthetic gene cluster. This phase I study was designed to evaluate the safety and pharmacokinetic(PK) profiles of UTD1 in patients with advanced solid tumors. Patients and methods: This was an open-label, single-arm, one site, phase I, dose-escalation study. Patients were treated with escalating doses of UTD1 as a 3-h intravenous infusion every 3 weeks. Results: Twenty-one patients were enrolled and received UTD1 at six dose levels ranging from 25 to 225 mg/m 2. Dose-limiting toxicity (DLT) was ataxia, and other frequent non-haematological toxicities were peripheral neuropathy, gastrointestinal disorders, fatigue, and myalgia/arthralgia. Myelosuppression was rare, with no grade 3 and 4 neutropenia, in contrast to paclitaxel and ixabepilone. The maximum-tolerated dose was established as 170 mg/m 2. Preliminary results showed linear pharmacokinetics along the range of doses tested. Prolonged disease stabilization was observed in patients with breast cancer, non-small lung cancer, and other cancers. Conclusions: The recommended phase II dose of UTD1 is 170 mg/m 2 as a 3-h infusion every 3 weeks. Ataxia was the DLT. UTD1 showed advantages over paclitaxel and Ixapebilone in relation to safety profile, especially myelosuppression. The acceptable tolerability warrants further phase II study. © 2011 Springer-Verlag. Source


Liu X.-J.,Dalian University of Technology | Kong R.-X.,Dalian University of Technology | Niu M.-S.,Dalian University of Technology | Qiu R.-G.,Dalian University of Technology | And 3 more authors.
Journal of Natural Products | Year: 2013

Fostriecin (FST, 1) is a natural product with promising antitumor activity produced by Streptomyces pulveraceus. Its antitumor activity is associated with the selective inhibition of protein phosphatase activities. The biosynthetic gene cluster for FST has recently been cloned and sequenced. To better understand the post-polyketide synthase (PKS) modification steps in the biosynthetic pathway of FST, we constructed and characterized three post-PKS modification gene mutants of fosG, fosK, and fosM by knockout inactivation in S. pulveraceus. As a result, we determined that a fosK-encoded cytochrome P450 monooxygenase is responsible for C-18 hydroxylation, formation of an unsaturated lactone is dependent upon FosM, and the fosG gene product is involved in hydroxylation at C-4 after the action of FosM to yield PD 113,271 from FST. The accumulated analogues from the ΔfosK and ΔfosM mutant strains possessed a malonyl ester moiety that suggested that all the post-PKS modification steps in FST biosynthesis occur with the polyketide chain bearing a malonyl ester at the C-3 position, with formation of the unsaturated six-membered lactone as the last step in FST biosynthesis. © 2013 The American Chemical Society and American Society of Pharmacognosy. Source


Su C.,Dalian University of Technology | Zhao X.-Q.,Dalian University of Technology | Wang H.-N.,Dalian University of Technology | Qiu R.-G.,Dalian University of Technology | And 3 more authors.
Gene | Year: 2015

Type I polyketides are natural products with diverse functions that are important for medical and agricultural applications. Manipulation of large biosynthetic gene clusters containing type I polyketide synthases (PKS) for heterologous expression is difficult due to the existence of conservative sequences of PKS in multiple modules. Red/ET mediated recombination has permitted rapid manipulation of large fragments; however, it requires insertion of antibiotic selection marker in the cassette, raising the problem of interference of expression by leaving "scar" sequence. Here, we report a method for precise seamless stitching of large polyketide biosynthetic gene cluster using a 48.4 kb fragment containing type I PKS involved in fostriecin biosynthesis as an example. rpsL counter-selection was used to assist seamless stitching of large fragments, where we have overcome both the size limitations and the restriction on endonuclease sites during the Red/ET recombination. The compatibility and stability of the co-existing vectors (p184 and pMT) which respectively accommodate 16 kb and 32.4 kb inserted fragments were demonstrated. The procedure described here is efficient for manipulation of large DNA fragments for heterologous expression. © 2014 Elsevier B.V. Source


Su C.,Dalian University of Technology | Zhao X.,Dalian University of Technology | Qiu R.,Dalian University of Technology | Qiu R.,Beijing Biostar Technologies Ltd. | And 2 more authors.
Pharmaceutical Biology | Year: 2015

Context: Polyketides are bioactive natural products with diverse bioactivities, and heterologous production of polyketides in easily engineered microbial hosts is preferred for the production of structurally diverse and the therapeutically active polyketides. Objective: In this study, heterologous expression of the biosynthetic genes encoding type I polyketide synthases (PKS) involved in biosynthesis of fostriecin, a unique phosphate monoester polyketide antibiotic, was attempted. Materials and methods: Fostriecin PKS (Fos-PKS) biosynthetic gene cluster in a total of 48.4kb were cloned downstream of the act I promoter in two compatible Streptomyces vectors using Red/ET recombination. The co-expression plasmids were sequentially transferred into Streptomyces lividans and Streptomyces coelicolor. Active transcription of the polyketide genes was confirmed by reverse transcription PCR (RT-PCR) analysis, and the metabolites were detected using high-performance liquid chromatography (HPLC). Results: The recombinant strains S. lividans TK24/p6-fosAB-p4-fosCDEF and S. coelicolor M512/p6-fosAB-p4-fosCDEF were obtained for heterologous expression in Streptomyces. Pigmentation was observed in the recombinant strains, whereas the control strain with empty vector displayed no change in pigment production. Active transcription of the polyketide genes was confirmed by RT-PCR analysis and subsequent sequencing. Conclusion: The present study is the first attempt to overexpress Fos-PKS biosynthetic gene cluster in Streptomyces. More studies on heterologous expression of the fostriecin biosynthetic gene cluster would be beneficial for further understanding the mechanisms of its structural as well as the potential pharmaceutically effect. © 2015 Informa Healthcare USA, Inc. Source

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