Bioreactor engineering as an enabling technology to tap biodiversity. The case of taxol

Concurrent chemoradiation for high-risk prostate cancer

There are estimated to be 220800 cases of prostate cancer diagnosed in 2015, making up 26% of all cancer diagnoses. Fortunately, adenocarcinoma of the prostate is often a highly treatable malignancy. Even though the majority of prostate cancer patients present with localized disease, prostate cancer still accounts for over 27000 deaths a year. There is a subset of patients that are likely to recur after locoregional treatment that is thought of as a “high-risk” population. This more aggressive subset includes patients with clinical stage greater than T2b, Gleason score greater than 7, and prostate specific antigen greater than 20 ng/dL. The rate of biochemical relapse in this high risk group is 32%-70% within five years of definitive focal therapy. Given these discouraging outcomes, attempts have been made to improve cure rates by radiation dose escalation, addition of androgen depravation therapy, and addition of chemotherapy either sequentially or concurrently with radiation. One method that has been shown to improve clinical outcomes is the addition of chemotherapy to radiotherapy for definitive treatment. Concurrent chemoradiation with 5-fluorouracil, estramustine phosphate, vincristine, docetaxel, and paclitaxel has been studied in the phase I and/or II setting. These trials have identified the maximum tolerated dose of chemotherapy and radiation that can be safely delivered concurrently and established the safety and feasibility of this technique. This review will focus on the addition of concurrent chemotherapy to radiotherapy in the definitive management of high-risk prostate cancer.

Total biosynthesis of antitumor nonribosomal peptides in Escherichia coli

Nonribosomal peptides (NRPs) are a class of microbial secondary metabolites that have a wide variety of medicinally important biological activities, such as antibiotic (vancomycin), immunosuppressive (cyclosporin A), antiviral (luzopeptin A) and antitumor (echinomycin and triostin A) activities. However, many microbes are not amenable to cultivation and require time-consuming empirical optimization of incubation conditions for mass production of desired secondary metabolites for clinical and commercial use. Therefore, a fast, simple system for heterologous production of natural products is much desired. Here we show the first example of the de novo total biosynthesis of biologically active forms of heterologous NRPs in Escherichia coli. Our system can serve not only as an effective and flexible platform for large-scale preparation of natural products from simple carbon and nitrogen sources, but also as a general tool for detailed characterizations and rapid engineering of biosynthetic pathways for microbial syntheses of novel compounds and their analogs.

Kinetics of two-liquid-phase Taxus cuspidata cell culture for production of Taxol

The effects of different organic solvents (paraffin, organic acid, alcohol and ester) and their volumetric fractions on the cell growth and Taxol production were studied in two-liquid-phase and the two-stage culture. A kinetic model, incorporated the effects of the toxicity of organic solvents was developed for two-liquid-phase culture of Taxus cuspidata in the two-stage Taxol production. The results showed that the proposed kinetic model could fit the experimental data satisfactorily. The results also showed that Taxol production could reach the optimal value when 10-logP was in the range of 2 to 5 and the volumetric fraction of the organic solvents at the corresponding the highest Taxol production should be lower when 10-logP was high.

Use of plant cell cultures in biotechnology

Plant cell cultures are being widely used in scientific studies on the physiology, biochemistry and molecular biology of primary and secondary metabolism, developmental regulation and cellular responses to pathogens and stress. In this chapter the significance of plant cell cultures in biotechnology is discussed with special emphasis on commercial production of secondary metabolites and pharmaceuticals, the potential of genetically transformed cell cultures, photosynthetically active cell cultures, production of somatic embryos, and novel assay systems based on the use of plant cells. Future aspects of biotechnical applications with respect to the potentials and limitations of these approaches are assessed, particularly in comparison with the productivity of lower eucaryotes.

Kinetics of taxol production and nutrient use in suspension cultures of Taxus cuspidata in shake flasks and a Wilson-type bioreactor

Suspension cultures of Taxus cuspidata were grown in shake flasks and Wilson-type reactors where bubbled air provided both agitation and mixing. Taxol titers of 22 mg l-1 were achieved for both configurations in 20 days for a volumetric productivity of 1.1 mg l-1 day-1. This productivity is many-fold higher than reported for other Taxus sp. suspension cultures. Taxol was released to the extracellular medium as it was produced with little intracellular retention (< or = 10%). Taxol production occurred during the last seven days of the cultivation period and was not growth-associated. Although the same taxol titers could be obtained in both reactor types, nutrient uptake rates were faster in the Wilson-type reactor than in shake flasks. Formation of a growth ring in the Wilson-type reactor reduced measured cell mass yields.