Rosmarinic acid Ameliorates neuronal regeneration in the bridging silicone rubber conduits of the sciatic nerve in taxol-treated rats

Background and aim

Taxol modulates local inflammatory conditions in peripheral nerves, which may impair their regeneration and recovery when injured. This study aimed to determine the effects of rosmarinic acid (RA, a polyphenol constituent of many culinary herbs) on the regeneration of the sciatic nerves in the bridging conduits.

Experimental procedure

In the cell study, RA decreased nuclear factor (NF)-κB activity induced by taxol in a dose dependency. In the animal model, taxol-treated rats were divided into 3 groups (n = 10/group): taxol (2 mg/kg body weight for 4 times) and taxol + RA (3 times/week for 4 weeks at 20 and 40 mg/kg body weight) groups. Macrophage infiltration, calcitonin gene-related peptide (CGRP) expression levels, neuronal connectivity, animal behavior, and neuronal electrophysiology were evaluated.

Results and conclusion

At the end of 4 weeks, macrophage density, CGRP expression level, and axon number significantly increased in the RA group compared with the taxol group. The RA administration unaffected heat, cold plate licking latencies, and motor coordination. Moreover, the 40 mg/kg RA group had significantly larger nerve conduction velocity and less latency compared to the taxol group. This study suggested that RA could ameliorate local inflammatory conditions to augment the recovery of regenerating nerves by accelerating their regrowth and improving electrophysiological function in taxol-treated peripheral nerve injury repaired with the silicone rubber conduit.

Synthetic biology for Taxol biosynthesis and sustainable production

Incomplete understanding of the biosynthetic pathway of the anticancer compound Taxol hinders its production by metabolic engineering. Recent reports by Jiang et al. and other groups now describe the missing steps in Taxol biosynthesis, notably including oxetane ring formation. These findings will promote the sustainable production of Taxol through synthetic biology.

Systematic profiling of Taxol resistance and sensitivity to tubulin missence mutations at molecular and cellular levels

Taxol (paclitaxel) is the first approved microtubule-stabilizing agent (MSA) by binding stoichiometrically to tubulin, which is considered to be one of the most significant advances in first-line chemotherapy against diverse tumors. However, a large number of residue missence mutations harboring in the tubulin have been observed to cause acquired drug resistance, largely limiting the clinical application of Taxol and its analogs in chemotherapy. A systematic investigation of the intermolecular interactions between the Taxol and various tubulin mutants would help to establish a comprehensive picture of drug response to tubulin mutations in clinical treatment of cancer, and to design new MSA agents with high potency and selectivity to overcome drug resistance. In this study, we described an integration of in silico analysis and in vitro assay (iSiV) to profile Taxol against a panel of 149 clinically observed, cancer-associated missence mutations in β-tubulin at molecular and cellular levels, aiming to a systematic understanding of molecular mechanism and biological implication underlying drug resistance and sensitivity conferring from tubulin mutations. It is revealed that the Taxol-resistant mutations can be classified into three types: (I) nonbonded interaction broken due to mutation, (II) steric hindrance caused by mutation, and (III) conformational change upon mutation. In addition, we identified three new Taxol-resistant mutations (C239Y, T274I, and R320P) that can largely reduce the binding affinity of Taxol to tubulin at molecular level, in which the T274I and R320P were observed to considerably impair the antitumor activity of Taxol at cellular level. Moreover, a novel drug-susceptible mutation (M363T) was also identified, which improves Taxol affinity by 2.6-fold and decreases Taxol antitumor EC50 values from 29.4 to 18.7 μM.

Alternaria alternata F3, a Novel Taxol-Producing Endophytic Fungus Isolated from the Fruits of Taxus cuspidata: Isolation, Characterization, Taxol Yield Improvement, and Antitumor Activity

In this study, a novel taxol-producing endophytic fungus, strain F3, was isolated from the fruits of Taxus cuspidata and identified as Alternaria alternata according to its macroscopic and microscopic traits and sequence analysis of internal transcribed spacer (ITS). The presence of taxol was detected by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) and confirmed by ultra-high-performance liquid chromatography-electrospray coupled to tandem mass spectrometry (UPLC-ESI-MS/MS) and nuclear magnetic resonance (NMR). The fermentation parameters of strain F3 were then optimized for high taxol production. The maximum taxol yield of 195.4 µg L-1 by A. alternata F3 was observed in 200-mL yeast peptone dextrose (YPD) broth, at an initial pH value of 6.0, supplemented with 0.1 g L-1 sodium acetate, 0.25 g L-1 salicylic acid, and 0.00125 g L-1 silver nitrate and inoculum size 2%, and incubated at 28 °C and 150 rpm for 8 days, which was 2.12-fold compared with the initial yield of taxol. Also, fungal taxol exhibited antitumor activity towards human lung carcinoma (A549) cell line and human cervical carcinoma (Hela) cell line with IC50 values of 3.98 µg mL-1 and 0.35 µg mL-1. Overall, this is the first report on taxol-producing endophytic fungus isolated from the fruits of Taxus. This study offers a novel source for the production of taxol for anticancer treatment.

Production and bioprocessing of Taxol from Aspergillus niger, an endophyte of Encephalartos whitelockii, with a plausible biosynthetic stability: antiproliferative activity and cell cycle analysis

The biosynthetic potency of Taxol by fungi raises their prospective to be a platform for commercial production of Taxol, nevertheless, the attenuation of its productivity with the fungal storage, is the challenge. Thus, screening for a novel fungal isolate inhabiting ethnopharmacological plants, with a plausible metabolic stability for Taxol production could be one of the most affordable approaches. Aspergillus niger OR414905.1, an endophyte of Encephalartos whitelockii, had the highest Taxol productivity (173.9 μg/L). The chemical identity of the purified Taxol was confirmed by HPLC, FTIR, and LC-MS/MS analyses, exhibiting the same molecular mass (854.5 m/z) and molecular fragmentation pattern of the authentic Taxol. The purified Taxol exhibited a potent antiproliferative activity against HepG-2, MCF-7 and Caco-2, with IC50 values 0.011, 0.016, and 0.067 μM, respectively, in addition to a significant activity against A. flavus, as a model of human fungal pathogen. The purified Taxol displayed a significant effect against the cellular migration of HepG-2 and MCF-7 cells, by ~ 52-59% after 72 h, compared to the control, confirming its interference with the cellular matrix formation. Furthermore, the purified Taxol exhibited a significant ability to prompt apoptosis in MCF-7 cells, by about 11-fold compared to control cells, suppressing their division at G2/M phase. Taxol productivity by A. niger has been optimized by the response surface methodology with Plackett-Burman Design and Central Composite Design, resulting in a remarkable ~ 1.6-fold increase (279.8 μg/L), over the control. The biological half-life time of Taxol productivity by A. niger was ~ 6 months of preservation at 4 ℃, however, the Taxol yield by A. niger was partially restored in response to ethyl acetate extracts of E. whitelockii, ensuring the presence of plant-derived signals that triggers the cryptic Taxol encoding genes.

Microtubule association of TRIM3 revealed by differential extraction proteomics

The microtubule network is formed from polymerised tubulin subunits and associating proteins, which govern microtubule dynamics and a diverse array of functions. To identify novel microtubule-binding proteins, we have developed an unbiased biochemical assay, which relies on the selective extraction of cytosolic proteins from U2OS cells, while leaving behind the microtubule network. Candidate proteins are linked to microtubules by their sensitivities to the depolymerising drug nocodazole or the microtubule-stabilising drug taxol, which is quantitated by mass spectrometry. Our approach is benchmarked by co-segregation of tubulin and previously established microtubule-binding proteins. We then identify several novel candidate microtubule-binding proteins, from which we have selected the ubiquitin E3 ligase tripartite motif-containing protein 3 (TRIM3) for further characterisation. We map TRIM3 microtubule binding to its C-terminal NHL-repeat region. We show that TRIM3 is required for the accumulation of acetylated tubulin, following treatment with taxol. Furthermore, loss of TRIM3 partially recapitulates the reduction in nocodazole-resistant microtubules characteristic of α-tubulin acetyltransferase 1 (ATAT1) depletion. These results can be explained by a decrease in ATAT1 following depletion of TRIM3 that is independent of transcription.

cerevisiae using combinatorial in silico design and metabolic engineering

BACKGROUND

Integrated metabolic engineering approaches that combine system and synthetic biology tools enable the efficient design of microbial cell factories for synthesizing high-value products. In this study, we utilized in silico design algorithms on the yeast genome-scale model to predict genomic modifications that could enhance the production of early-step Taxol® in engineered Saccharomyces cerevisiae cells.

RESULTS

Using constraint-based reconstruction and analysis (COBRA) methods, we narrowed down the solution set of genomic modification candidates. We screened 17 genomic modifications, including nine gene deletions and eight gene overexpressions, through wet-lab studies to determine their impact on taxadiene production, the first metabolite in the Taxol® biosynthetic pathway. Under different cultivation conditions, most single genomic modifications resulted in increased taxadiene production. The strain named KM32, which contained four overexpressed genes (ILV2, TRR1, ADE13, and ECM31) involved in branched-chain amino acid biosynthesis, the thioredoxin system, de novo purine synthesis, and the pantothenate pathway, respectively, exhibited the best performance. KM32 achieved a 50% increase in taxadiene production, reaching 215 mg/L. Furthermore, KM32 produced the highest reported yields of taxa-4(20),11-dien-5α-ol (T5α-ol) at 43.65 mg/L and taxa-4(20),11-dien-5-α-yl acetate (T5αAc) at 26.2 mg/L among early-step Taxol® metabolites in S. cerevisiae.

CONCLUSIONS

This study highlights the effectiveness of computational and integrated approaches in identifying promising genomic modifications that can enhance the performance of yeast cell factories. By employing in silico design algorithms and wet-lab screening, we successfully improved taxadiene production in engineered S. cerevisiae strains. The best-performing strain, KM32, achieved substantial increases in taxadiene as well as production of T5α-ol and T5αAc. These findings emphasize the importance of using systematic and integrated strategies to develop efficient yeast cell factories, providing potential implications for the industrial production of high-value isoprenoids like Taxol®.

Green synthesized Ag nanoparticles stimulate gene expression and paclitaxel production in Corylus avellana cells

Synthesis of nanoparticles (NPs) through plant extracts has been suggested as an effective and nature-friendly method. Paclitaxel is one of the most valuable secondary metabolites with therapeutic uses, and hazelnut has been suggested as one of the sustainable resources for producing this metabolite. In the present study, we synthesized Ag NPs using the ethanolic extract of C. avellana leaves and were characterized using UV-visible, FTIR, XRD, EDX, DLS, SEM, and TEM analyses. In addition, we investigated the effect of green synthesized Ag (GS Ag) NPs (5 and 10 mg/L), para-aminobenzoic acid (PABA) (20 mg/L), and AgNO3 (10 mg/L) on cell viability, physiological characteristics, gene expression, and biosynthesis of secondary metabolites in hazelnut cell cultures. The results showed that 10 mg/L Ag NPs and AgNO3 significantly affected the cell viability, the content of ROS, peroxidation of lipids, antioxidant capacity, secondary metabolite production, and expression pattern of the genes involved in the taxanes biosynthesis pathway in the hazelnut cells. The cytotoxicity increased by increasing the GS Ag NPs concentration from 5 to 10 mg/L, which was associated with reduced membrane integrity and cell viability. Elicitation of the cells with 10 mg/L Ag NPs combined with 20 mg/L PABA (as a precursor) remarkably excited the expression of TAT and GGPPS genes and the production of secondary metabolites as well as paclitaxel. So that the highest expression of TAT and GGPPS genes (3.71 and 3.69) and the highest amount of taxol (230.21 μg g-1 FW) and baccatin (1025.8 μg g-1 FW) were observed in this treatment. KEY POINTS: • For the first time, we assessed and reported the molecular and physiological responses of C. avellana cells to GS Ag NPs, AgNO3, and PABA. • In hazel cells, GS Ag NPs stimulate several physiological and molecular responses. • In addition to increasing antioxidant activity, GS Ag NPs significantly increased the expression of genes involved in the paclitaxel biosynthesis pathway and the production of secondary metabolites.

Treatment of CHO cells with Taxol and reversine improves micronucleation and microcell-mediated chromosome transfer efficiency

Microcell-mediated chromosome transfer is an attractive technique for transferring chromosomes from donor cells to recipient cells and has enabled the generation of cell lines and humanized animal models that contain megabase-sized gene(s). However, improvements in chromosomal transfer efficiency are still needed to accelerate the production of these cells and animals. The chromosomal transfer protocol consists of micronucleation, microcell formation, and fusion of donor cells with recipient cells. We found that the combination of Taxol (paclitaxel) and reversine rather than the conventional reagent colcemid resulted in highly efficient micronucleation and substantially improved chromosomal transfer efficiency from Chinese hamster ovary donor cells to HT1080 and NIH3T3 recipient cells by up to 18.3- and 4.9-fold, respectively. Furthermore, chromosome transfer efficiency to human induced pluripotent stem cells, which rarely occurred with colcemid, was also clearly improved after Taxol and reversine treatment. These results might be related to Taxol increasing the number of spindle poles, leading to multinucleation and delaying mitosis, and reversine inducing mitotic slippage and decreasing the duration of mitosis. Here, we demonstrated that an alternative optimized protocol improved chromosome transfer efficiency into various cell lines. These data advance chromosomal engineering technology and the use of human artificial chromosomes in genetic and regenerative medical research.

Phytochemical and metabolic profiling of the different Podocarpus species in Egypt: Potential antimicrobial and antiproliferative activities

Podocarpus is the most dominant genus of Podocarpaceae, with higher taxonomical proximity to the Taxaceae, having numerous pharmaceutical applications, however, scarce studies dealing with the physiological and metabolic criteria of Podocarpus in Egypt were reported. Thus, the objective of this work was to assess the physiological and metabolical patterns of the different species of Podocarpus; P. gracilior, P. elongates, P. macrophyllus and P. neriifolius. The highest terpenoids contents were reported in P. neriifolius, followed by P. elongatus, and P. macrophyllus. P. gracilior had the highest antioxidants amount, followed by P. macrophyllus, P. neriifolius and P. elongatus. From the GC/MS metabolic profiling, caryophyllene, β-cadinene, β-cuvebene, vitispirane, β-cadinene and amorphene were the most dominant metabolites in P. gracilior. β-Caryophyllene was the common in P. gracilior, P. elongatus, P. macrophyllus and P. neriifolius with an obvious fluctuation. The plant methanolic extracts have an obvious activity against the multidrug resistant bacteria; E. coli, P. aeruginosa, S. pyogenes and S. aureus, and fungi; A. fumigatus, A. flavus, A. niger and C. albicans in a concentration-dependent manner. The highest Taxol yield was assessed in the extracts of P. elongatus (16.4 μg/gdw), followed by P. macrophyllus, and P. neriifolius. The chemical identity of Taxol derived from P. elongatus was resolved by LC/MS, with molecular mass 854.6 m/z, and similar structural fragmentation pattern of the authentic one. The highest antitumor activity of P. elongatus extracted Taxol was assessed towards HCT-116 (30.2 μg/ml), HepG-2 (53.7 μg/ml) and MCF-7 (71.8 μg/ml). The ITS sequence of P. elongatus "as potent Taxol producer" was deposited on Genbank with accession #ON540734.1, that is the first record of Podocarpus species on Genbank.

Skin Extracellular Matrix Breakdown Following Paclitaxel Therapy in Patients with Chemotherapy-Induced Peripheral Neuropathy

The chemotherapeutic agent paclitaxel causes peripheral neuropathy, a dose-limiting side effect, in up to 68% of cancer patients. In this study, we investigated the impact of paclitaxel therapy on the skin of breast cancer patients with chemotherapy-induced peripheral neuropathy (CIPN), building upon previous findings in zebrafish and rodents. Comprehensive assessments, including neurological examinations and quality of life questionnaires, were conducted, followed by intraepidermal nerve fiber (IENF) density evaluations using skin punch biopsies. Additionally, RNA sequencing, immunostaining for Matrix-Metalloproteinase 13 (MMP-13), and transmission electron microscopy provided insights into molecular and ultrastructural changes in this skin. The results showed no significant difference in IENF density between the control and CIPN patients despite the presence of patient-reported CIPN symptoms. Nevertheless, the RNA sequencing and immunostaining on the skin revealed significantly upregulated MMP-13, which is known to play a key role in CIPN caused by paclitaxel therapy. Additionally, various genes involved in the regulation of the extracellular matrix, microtubules, cell cycle, and nervous system were significantly and differentially expressed. An ultrastructural examination of the skin showed changes in collagen and basement membrane structures. These findings highlight the presence of CIPN in the absence of IENF density changes and support the role of skin remodeling as a major contributor to CIPN.

Naringin and naringenin counteract taxol-induced liver injury in Wistar rats via suppression of oxidative stress, apoptosis and inflammation

This research aimed to evaluate the preventing effects of naringin, naringenin, and their combination on liver injury induced by Taxol (paclitaxel) in Wistar rats. Male Wistar rats received 2 mg/kg Taxol intraperitoneal injections twice weekly on the second and fifth days of each week for 6 weeks. During the same period as Taxol administration, rats were given naringin, naringenin, or a combination of the two (10 mg/kg b.wt) every other day. Treatment with naringin and/or naringenin reduced the abnormally high serum levels of total bilirubin, aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase, and gamma-glutamyl transferase in Taxol-treated rats. It also significantly increased the level of serum albumin, indicating an improvement in the liver. The perturbed histological liver changes were markedly improved due to the naringin and/or naringenin treatment in Taxol-administered rats. Additionally, the treatments reduced high hepatic lipid peroxidation and increased liver glutathione content as well as the activities of superoxide dismutase and glutathione peroxidase. Furthermore, the treatments reduced the levels of alpha-fetoprotein and caspase-3, a pro-apoptotic mediator. The naringin and naringenin mixture appeared more effective in improving organ function and structural integrity. In conclusion, naringin and naringenin are suggested to employ their hepatoprotective benefits via boosting the body's antioxidant defense system, reducing inflammation, and suppressing apoptosis.

PARP deficiency causes hypersensitivity to Taxol through oxidative stress induced DNA damage

Taxol is an antitumor drug derived from the bark of the Pacific Yew tree that inhibits microtubule disassembly, resulting in cell cycle arrest in late G2 and M phases. Additionally, Taxol increases cellular oxidative stress by generating reactive oxygen species. We hypothesized that the inhibition of specific DNA repair machinery/mechanisms would increase cellular sensitivity to the oxidative stress capacity of Taxol. Initial screening using Chinese hamster ovary (CHO) cell lines demonstrated that base excision repair deficiency, especially PARP deficiency, caused cellular Taxol hypersensitivity. Taxane diterpenes-containing Taxus yunnanensis extract also showed hypertoxicity in PARP deficient cells, which was consistent with other microtubule inhibitors like colcemid, vinblastine, and vincristine. Acute exposure of 50 nM Taxol treatment induced both significant cytotoxicity and M-phase arrest in PARP deficient cells, but caused neither significant cytotoxicity nor late G2-M cell cycle arrest in wild type cells. Acute exposure of 50 nM Taxol treatment induced oxidative stress and DNA damage. The antioxidant Ascorbic acid 2 glucoside partially reduced the cytotoxicity of Taxol in PARP deficient cell lines. Finally, the PARP inhibitor Olaparib increased cytotoxicity of Taxol in wild type CHO cells and two human cancer cell lines. Our study clearly demonstrates that cytotoxicity of Taxol would be enhanced by inhibiting PARP function as an enzyme implicated in DNA repair for oxidative stress.

The first facile optical density-dependent approach for the analysis of doxorubicin, an oncogenic agent accompanied with the co-prescribed drug; paclitaxel

Doxorubicin (DRB) is an anthracycline oncogenic drug extracted from cultures of Streptomyces peucetius var. caesius. It is frequently recommended as an anti-neoplastic agent for the treatment of diverse malignancies. It exerts its antineoplastic effect either via inhibiting the enzyme topoisomerase II and/or via intercalation to DNA or reactive oxygen species generation. In the present article, the direct, simple, one-pot, somewhat eco-safe, and non-extractive spectrophotometric system was executed to track doxorubicin, a chemotherapeutic remedy, in the presence of paclitaxel, a naturally occurring Taxan antineoplastic radical, through the greenness rated method. DRB's optical density was studied in various mediums and solvents to develop the current approach. An acidic ethanolic solution was found to increase the optical density of the sample significantly. At 480 nm., the most remarkable optical density was obtained. Various experimental factors, including intrinsic media, solvent, pH, and stability time, were investigated and controlled. The current approach achieved linearity within the 0.6-40.0 µg mL-1 range, accompanied by a limit of both detection and quantification (LOD and LOQ) of 0.18 and 0.55 µg mL-1, correspondingly. The approach was validated under the ICH guidelines (Quality Guidelines). The system's greenness and enhancement degree were estimated.

Action of the plant-based essential oil-derived compound Taxol for improvising drought tolerance in Eucalyptus by modulating the VIT1 channel protein: a cutting-edge computational approach

Background: Drought poses a significant threat to the growth and survival of woody plants, especially Eucalyptus grandis, which is known for its slow and steady growth. Understanding the physiological and molecular responses of E. grandis to abiotic stress is essential for developing strategies to improve its drought resistance. This study focuses on the potential vulnerability of E. grandis during the initial months of root system proliferation and investigates the role of the essential oil-derived compound Taxol in enhancing its drought resistance. Methodology: A comprehensive analysis was performed on various aspects of E. grandis, including morphological features, photosynthetic rates, pigment concentrations, nitrogenous components, and lipid peroxidation. Furthermore, the study examined the accumulation of soluble carbohydrates, proline, and antioxidant enzymes as part of the tree's response to drought stress. Molecular docking and molecular dynamics simulations were conducted to determine the binding affinity of Taxol, an essential oil derived from Taxus brevifolia, with the VIT1 protein in E. grandis. Results: E. grandis displayed remarkable resilience to drought by accumulating vast reserves of soluble carbohydrates, proline, and antioxidant enzymes. The essential oil-derived compound Taxol exhibited a strong binding affinity with the VIT1 protein (-10.23 kcal/mol), suggesting its potential role in enhancing the tree's drought resistance. Conclusion: This study reveals the pivotal role of Taxol in augmenting the resilience of E. grandis against drought stress and improving its therapeutic oil properties. Emphasizing the tree's inherent tolerance during its susceptible early stages is crucial in promoting sustainable agriculture and forestry practices. The findings underscore the importance of advanced scientific research in uncovering the concealed capabilities of robust trees like E. grandis as we continue our pursuit of a sustainable future.

Low dose Taxol ameliorated renal fibrosis in mice with diabetic kidney disease by downregulation of HIPK2

Our previous studies reported that low-dose paclitaxel (Taxol) ameliorated renal fibrosis in the unilateral ureteral obstruction and remnant kidney models. However, the regulatory role of Taxol in diabetic kidney disease (DKD) is still unclear. Herein, we observed that low-dose Taxol attenuated high glucose-increased expression of fibronectin, collagen I and collagen IV in Boston University mouse proximal tubule cells. Mechanistically, Taxol suppressed the expression of homeodomain-interacting protein kinase 2 (HIPK2) via disrupting the binding of Smad3 to HIPK2 promoter region, and consequently inhibited the activation of p53. Besides, Taxol ameliorated RF in Streptozotocin mice and db/db-induced DKD via suppression of Smad3/HIPK2 axis as well as inactivation of p53. Altogether, these results suggest that Taxol can block Smad3-HIPK2/p53 axis, thereby attenuating the progression of DKD. Hence, Taxol is a promising therapeutic drug for DKD.

Autophagy in cancer resistance to paclitaxel: Development of combination strategies

Paclitaxel, a compound naturally occurring in yew, is a commonly used drug for the treatment of different types of cancer. Unfortunately, frequent cancer cell resistance significantly decreases its anticancer effectivity. The main reason for the resistance development is the paclitaxel-induced phenomenon of cytoprotective autophagy occurring by different mechanisms of action in dependence on a cell type and possibly even leading to metastases. Paclitaxel also induces autophagy in cancer stem cells, which greatly contributes to tumor resistance development. Paclitaxel anticancer effectivity can be predicted by the presence of several autophagy-related molecular markers, such as tumor necrosis factor superfamily member 13 in triple-negative breast cancer or cystine/glutamate transporter encoded by the SLC7A11 gene in ovarian cancer. Nevertheless, the undesired effects of paclitaxel-induced autophagy can be eliminated by paclitaxel co-administration with autophagy inhibitors, such as chloroquine. Interestingly, in certain cases, it is worthy of potentiating autophagy by paclitaxel combination with autophagy inducers, for instance, apatinib. A modern strategy in anticancer research is also to encapsulate chemotherapeutics into nanoparticle carriers or develop their novel derivatives with improved anticancer properties. Hence, in this review article, we summarize not only the current knowledge of paclitaxel-induced autophagy and its role in cancer resistance but mainly the possible drug combinations based on paclitaxel and their administration in nanoparticle-based formulations as well as paclitaxel analogs with autophagy-modulating properties.

Taxol‑resistant breast cancer cell‑derived exosome‑delivered miR‑187‑5p regulates the growth of breast cancer cells via ABCD2 and Wnt/β‑catenin signaling

Acquired resistance to Taxol (TAX) contributes to clinical treatment failure and significantly reduces the survival rate of patients. The present study aimed to explore the effects of exosomal microRNA (miR)-187-5p on TAX resistance in breast cancer cells and its underlying mechanisms. Exosomes were isolated from MCF-7 and TAX-resistant MCF-7/TAX cells, and the miR-187-5p and miR-106a-3p levels of the cells and exosomes were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Next, MCF-7 cells were treated with TAX for 48 h and either treated with exosomes or transfected with miR-187-5p mimics. Cell viability, apoptosis, migration, invasion and colony formation were determined using Cell Counting Kit-8, flow cytometry, Transwell and colony formation assays, and the expression levels of associated genes and proteins were detected by RT-qPCR and western blotting, respectively. Finally, a dual-luciferase reporter gene assay was performed to confirm the target of miR-187-5p. The results showed that miR-187-5p expression levels increased significantly in TAX-resistant MCF-7 cells and exosomes compared with normal MCF-7 cells and exosomes (P<0.05). However, miR-106a-3p was not detected in the cells or exosomes. Therefore, miR-187-5p was selected for subsequent experiments. A series of cell assays showed that TAX inhibited the viability, migration, invasion and colony formation of MCF-7 cells and promoted their apoptosis; however, these changes were reversed by resistant cell exosomes and miR-187-5p mimics. Additionally, TAX significantly upregulated ABCD2 and downregulated β-catenin, c-Myc and cyclin D1, whereas resistant exosomes and miR-187-5p mimics reversed the TAX-induced changes in expression. Finally, ABCD2 was confirmed to directly bind with miR-187-5p. It may be concluded that TAX-resistant cell-derived exosomes delivering miR-187-5p may affect the growth of TAX-induced breast cancer cells by targeting ABCD2 and c-Myc/Wnt/β-catenin signaling.

Purification and characterization of Taxol and 10-Deacetyl baccatin III from the bark, needles, and endophytes of Taxus baccata by preparative high-performance liquid chromatography, ultra-high-performance liquid chromatography-mass spectrometry, and nuclear magnetic resonance

Taxol and 10-Deacetyl baccatin III are major taxanes in the bark, needles, and endophytes of Taxus baccata. The current study aimed to develop a process for their separation from different matrices. Crude taxoid was prepared by extraction of samples with methanol, followed by partitioning with dichloromethane and precipitation with hexane. Analytical high-performance liquid chromatography involved isocratic elution on C18 column (4.6 × 250 mm, 5 μm) with methanol-water (70:30 v/v) at a flow rate of 1 ml/min. Injection volume was 20 μl and detection was carried out at 227 nm. The content of Taxol and 10-Deacetyl baccatin III in bark, needles and endophytic culture broth was 11.19 and 1.75 μg/mg; 11.19 and 1.75 μg/mg; and 2.80 and 0.22 μg/L, respectively. Preparative high-performance liquid chromatography was done on C18 column (10 × 250 mm, 5 μm) at a flow rate of 10 ml/min. About 20 g crude taxoid was processed in < 3 h with a recovery of about 90% for both the analytes. The purity of recovered Taxol and 10-Deacetyl baccatin III determined by ultra-high-performance liquid chromatography-mass spectrometry was found to be 95.78 ± 3.63% and 99.72 ± 0.18%, respectively. The structure of recovered Taxol was confirmed by nuclear magnetic resonance. The method can find use in biotransformation studies.

Antitumor Activity of Taxol Engross Taxol-Caveolin-1 Interaction via Lipid Raft Structure-"Caveolae"

Taxol is one of the most widely used natural antitumor drugs that have shown considerable success in treating cancers of different lineage. However, the development of resistance to taxol is still a significant issue. Caveolae, the cave-like structures found on the surface of many cancerous cells, are enriched in cholesterol and are known to play a pivotal role in drug uptake. Caveolin-1 (Cav-1), the principal structural proteins of the caveolae, interacts with signaling molecules through a scaffolding domain. In the present study, we observed that Cav-1-GFP clusters were instantly recruited to the cell membrane. Interestingly, Caveolae formation followed by internalization was observed after the treatment with time. The recruitment and the formation of the Cav-1-GFP clusters are provided in supplementary video 2 (SV2). The results obtained from molecular docking indicate favorable taxol-Cav-1 interaction. To further confirm the influence of Cav-1 proteins in the uptake and effects of taxol, the cells were treated with beta-cyclodextrin (β-CD), cholesterol, and taxol combinations. The result suggests that the depletion of cholesterol in HeLa cells makes them less susceptible to taxol at a lower concentration. These observations provide evidence of the interaction between Cav-1 and taxol. Further studies that may elucidate the molecular mechanism of uptake of taxol through caveolae/Cav-1 will help to determine if Cav-1 can be used to increase the uptake of taxol by cancer cells and sensitize the drug-resistant cancer cells to taxol.

E3 Ubiquitin Ligase TRIP12 Controls Exit from Mitosis via Positive Regulation of MCL-1 in Response to Taxol

Chemotherapy resistance is a major hurdle in cancer treatment. Taxol-based chemotherapy is widely used in the treatment of cancers including breast, ovarian, and pancreatic cancer. Loss of function of the tumor suppressor F-box WD-40 domain containing 7 (FBW7) mutations leads to the accumulation of its substrate MCL-1 which is associated with Taxol resistance in human cancers. We recently showed that E3 ubiquitin ligase TRIP12 is a negative regulator of FBW7 protein. In this study, we find that Taxol-induced mitotic block in cancer cells is partly controlled by TRIP12 via its positive regulation of MCL-1 protein. Genetic inhibition of TRIP12 accelerates MCL-1 protein degradation in mitosis. Notably, introducing double-point mutations in lysines 404/412 of FBW7 to arginine which makes it resistant to proteasomal degradation, leads to the sharp reduction of MCL-1 protein levels and sensitizes cancer cells to Taxol-induced cell death. Finally, TRIP12 deletion leads to enhanced mitotic arrest and cell death in an FBW7 and MCL-1 dependent manner in multiple cell lines including colorectal and ovarian cancer but not in breast cancer. Thus, the TRIP12/FBW7/MCL-1 axis may provide a therapeutic target to overcome Taxol-associated chemotherapy resistance in cancer.

Inhibition of STAT3 reverses Taxol-resistance in ovarian cancer by down-regulating G6PD expression in vitro

Ovarian cancer is the eminent gynecological malignancy and chemoresistance remains a major reason for poor in ovarian cancer patients. Taxol has been proved as the most effective chemotherapeutic agent against ovarian cancer. However development of Taxol resistance remains a major problem. Here, we report that STAT3, directly activates pentose-phosphate pathway to exert pro-oncogenic effects on Taxol resistance of ovarian cancer. In addition, we found that STAT3, p-STAT3 and glucose-6-phosphate dehydrogenase (G6PD) protein levels are upregulated in Taxol resistant cell lines compared with Taxol sensitive cell lines. Furthermore, inhibition of STAT3 decreased G6PD mRNA expression level and enhanced the sensitivity of Taxol resistant cell to Taxol. Finally, we found that STAT3 directly binds to the G6PD promoter region and promotes the expression of G6PD at transcriptional level. Taken together, our data indicate that activation of STAT3 promotes ovarian cancer cell proliferation, colony formation, and Taxol resistance via augmenting G6PD expression and pentose-phosphate metabolism flux, which provides a potential therapeutic target that may improve prognosis by decreasing G6PD expression and enhancing Taxol-sensitivity.

Triple negative breast cancer: approved treatment options and their mechanisms of action

PURPOSE

Breast cancer, the most prevalent cancer worldwide, consists of 4 main subtypes, namely, Luminal A, Luminal B, HER2-positive, and Triple-negative breast cancer (TNBC). Triple-negative breast tumors, which do not express estrogen, progesterone, and HER2 receptors, account for approximately 15-20% of breast cancer cases. The lack of traditional receptor targets contributes to the heterogenous, aggressive, and refractory nature of these tumors, resulting in limited therapeutic strategies.

METHODS

Chemotherapeutics such as taxanes and anthracyclines have been the traditional go to treatment regimens for TNBC patients. Paclitaxel, docetaxel, doxorubicin, and epirubicin have been longstanding, Food and Drug Administration (FDA)-approved therapies against TNBC. Additionally, the FDA approved PARP inhibitors such as olaparib and atezolizumab to be used in combination with chemotherapies, primarily to improve their efficiency and reduce adverse patient outcomes. The immunotherapeutic Keytruda was the latest addition to the FDA-approved list of drugs used to treat TNBC.

RESULTS

The following review aims to elucidate current FDA-approved therapeutics and their mechanisms of action, shedding a light on the various strategies currently used to circumvent the treatment-resistant nature of TNBC cases.

CONCLUSION

The recent approval and use of therapies such as Trodelvy, olaparib and Keytruda has its roots in the development of an understanding of signaling pathways that drive tumour growth. In the future, the emergence of novel drug delivery methods may help increase the efficiency of these therapies whiel also reducing adverse side effects.

Biologically synthesized CuO nanoparticles induce physiological, metabolic, and molecular changes in the hazel cell cultures

The utilization of plant extracts in nanoparticle (NP) synthesis has been suggested as a nature-friendly method and an efficient alternative to the conventional approaches such as physical and chemical methods. Taxol is a valuable medicinal compound, and hazelnut has been suggested as one of the sustainable resources for producing this metabolite. In the present research, copper oxide (CuO) nanoparticles (NPs) were biologically synthesized by utilizing hazelnut leaf extracts. FTIR, XRD, EDAX, DLS, and SEM analyses were used for characterizing and confirming the synthesized NPs. The effect of biosynthesized CuO NPs (10 and 90 ppm), para-aminobenzoic acid (PABA) (20 ppm), and CuSO₄ (10 ppm) on the cell viability, biochemical properties, expression of TAT and GGPPS genes, and accumulation of taxol and baccatin III in hazelnut cell cultures was investigated. The results indicated that biosynthesized CuO NPs significantly influenced the cell viability, amount of ROS, antioxidant capacity, lipid peroxidation, secondary metabolite production, and expression pattern of the genes engaged in the biosynthesis pathway of taxanes in the C. avellana L. cells. The cytotoxicity of CuO NPs to cells was dose dependent and increased with increasing its concentration, as evidenced by a decline in the survival rate and cell membrane integrity. Furthermore, the utilization of 10 ppm CuSO₄ caused more toxicity in the cells than the same concentration of CuO NPs. This result could be attributed to the fact that plant extracts components act as a coating for the NPs and reduce their toxicity. Treatment of the cell cultures with CuO (10 ppm) + PABA (20 ppm) and CuO (10 ppm) induced the highest radical scavenging activity. The activity of antioxidant enzymes was increased with increasing the copper oxide NPs level from 10 to 90 ppm. Contrariwise, the cell's survival rate, radical scavenging activity, and amount of secondary metabolites were significantly reduced in the higher levels of copper oxide NPs (90 ppm) compared to the 10 ppm. The combined utilization of 10 ppm copper oxide NPs and 20 ppm PABA considerably stimulated the TAT and GGPPS genes expression and produced the highest amount of taxol and baccatin III. KEY POINTS: • CuO NPs were biologically synthesized using the hazel leaf extracts and confirmed by FTIR, XRD, EDAX, DLS, and SEM analyses. • CuO NPs significantly affected the amount of ROS, antioxidant capacity, and lipid peroxidation in C. avellana L. cells. • Treatment of the hazel cells with CuO NPs increased the production of secondary metabolites including taxol and baccatin III and expression of the genes involved in taxol and baccatin III biosynthesis (TAT and GGPPS).

The Epigenetic Regulation in Plant Specialized Metabolism: DNA Methylation Limits Paclitaxel in vitro Biotechnological Production

Environmental conditions are key factors in the modulation of the epigenetic mechanisms regulating gene expression in plants. Specifically, the maintenance of cell cultures in optimal in vitro conditions alters methylation patterns and, consequently, their genetic transcription and metabolism. Paclitaxel production in Taxus x media cell cultures is reduced during its maintenance in in vitro conditions, compromising the biotechnological production of this valuable anticancer agent. To understand how DNA methylation influences taxane production, the promoters of three genes (GGPPS, TXS, and DBTNBT) involved in taxane biosynthesis have been studied, comparing the methylation patterns between a new line and one of ~14 years old. Our work revealed that while the central promoter of the GGPPS gene is protected from cytosine methylation accumulation, TXS and DBTNBT promoters accumulate methylation at different levels. The DBTNBT promoter of the old line is the most affected, showing a 200 bp regulatory region where all the cytosines were methylated. This evidence the existence of specific epigenetic regulatory mechanisms affecting the last steps of the pathway, such as the DBTNBT promoter. Interestingly, the GGPPS promoter, a regulatory sequence of a non-specific taxane biosynthetic gene, was not affected by this mechanism. In addition, the relationship between the detected methylation points and the predicted transcription factor binding sites (TFBS) showed that the action of TFs would be compromised in the old line, giving a further explanation for the production reduction in in vitro cell cultures. This knowledge could help in designing novel strategies to enhance the biotechnological production of taxanes over time.

Simultaneous chemotherapy/sonodynamic therapy of the melanoma cancer cells using a gold-paclitaxel nanostructure

Nanodrug delivery systems are novel strategies for tumor treatment since delivery of chemotherapy drugs such as paclitaxel (PTX) is associated with substantial challenges due to its poor aqueous solubility. In addition, sonodynamic therapy (SDT) is a promising approach that can increase the uptake, accumulation, and dispersion of desirable amounts of the drugs by activating sonosensitizer and enhancing cell membrane permeability. Herein, gold-paclitaxel nanoparticles (Au-PTX NPs) were synthesized and characterized to evaluate the cytotoxicity toward C540 cancer cells in comparison of free PTX, AuNPs, and AuNPs+free PTX in the absence and presence of ultrasound radiation. Evidence shows that AuNPs have a median diameter size of 95.0 ± 15.4, while the size of Au-PTX NPs is roughly 219.7 ±  40.4 nm. Negative zeta-potential results indicate high stability and good dispersion of nanoparticles. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay results revealed that Au-PTX NPs increased the cytotoxicity compared to other treatment groups that ensure the great potential of AuNPs as a promising nano-carrier for PTX drug delivery. Moreover, the viability of C540 cells treated by Au-PTX NPs under ultrasound radiation was decreased significantly by generating more reactive oxygen species (ROS) upon STD, with representing synergism effects confirming the role of gold nanoparticles as an excellent sonosensitizer and the role of SDT as an adjunctive treatment method with chemotherapy.

Pre-medication protocols for the prevention of paclitaxel-induced infusion related reactions: a systematic review and meta-analysis

BACKGROUND

Prophylaxis against infusion-related reactions (IRR) from paclitaxel with steroids and antihistamines is a standard of care due to high rates of IRR. This systematic review and meta-analysis aimed to comprehensively summarize the evidence behind various prophylaxis strategies.

METHODS

EMBASE, MEDLINE, PubMed, and the Cochrane Register of Controlled Trials were searched (1946 to May 14, 2021). The primary outcomes were Grade 3/4 IRR and any-grade IRR. Secondary outcomes included treatment delay or discontinuation and adverse events secondary to pre-medications.

RESULTS

Of the 1285 unique citations, 26 studies were selected: 11 studies for quantitative analysis and 15 studies for qualitative analysis. Studies included randomized controlled trials and observational studies (n = 25-281). There was a non-significant benefit in favour of oral steroids starting 12 h prior to paclitaxel administration versus intravenous steroids immediately prior to paclitaxel administration for grade 3/4 IRRs, with a risk difference (RD) of 2% [95%CI 0 to 5%], any-grade IRR with a RD of 4% [95%CI: -1% to 9%] and treatment discontinuation with a RD of 1% [95%CI -1% to 2%]. For de-escalation strategies, a point-estimate for any-grade IRR was 0.44% [95% CI, 0 to 0.02, p = 0.98] and for grade 3/4 IRR was 3.1% (95% CI, 0.02 to 0.07, p = 0.11).

CONCLUSION

Although studies have high risk of bias and risk, differences between steroid routes of administration were small, there was a non-significant trend in favour of oral steroids. De-escalation strategies after two previous successful paclitaxel infusions have an overall low incidence rate of severe IRR and warrant further prospective clinical trials. Insufficient evidence remains to recommend for or against other interventions for the prevention of paclitaxel IRR.

Enhancing Saccharomyces cerevisiae Taxane Biosynthesis and Overcoming Nutritional Stress-Induced Pseudohyphal Growth

The recent technological advancements in synthetic biology have demonstrated the extensive potential socio-economic benefits at laboratory scale. However, translations of such technologies to industrial scale fermentations remains a major bottleneck. The existence and lack of understanding of the major discrepancies in cultivation conditions between scales often leads to the selection of suboptimal bioprocessing conditions, crippling industrial scale productivity. In this study, strategic design of experiments approaches were coupled with state-of-the-art bioreactor tools to characterize and overcome nutritional stress for the enhanced production of precursors to the blockbuster chemotherapy drug, Taxol, in S. cerevisiae cell factories. The batch-to-batch variation in yeast extract composition was found to trigger nutritional stress at a mini-bioreactor scale, resulting in profound changes in cellular morphology and the inhibition of taxane production. The cells shifted from the typical budding morphology into striking pseudohyphal cells. Doubling initial yeast extract and peptone concentrations (2×YP) delayed filamentous growth, and taxane accumulation improved to 108 mg/L. Through coupling a statistical definitive screening design approach with the state-of-the-art high-throughput micro-bioreactors, the total taxane titers were improved a further two-fold, compared to the 2×YP culture, to 229 mg/L. Filamentous growth was absent in nutrient-limited microscale cultures, underlining the complex and multifactorial nature of yeast stress responses. Validation of the optimal microscale conditions in 1L bioreactors successfully alleviated nutritional stress and improved the titers to 387 mg/L. Production of the key Taxol precursor, T5αAc, was improved two-fold to 22 mg/L compared to previous maxima. The present study highlights the importance of following an interdisciplinary approach combining synthetic biology and bioprocessing technologies for effective process optimization and scale-up.

The Effect of Tau and Taxol on Polymerization of MCF7 Microtubules In Vitro

Overexpression of Tau protein in breast cancer cells is identified as an indicator for potential resistance to taxane-based therapy. As reported findings have been obtained mostly from clinical studies, the undetermined underlying mechanism of such drug resistance needs to be thoroughly explored through comprehensive in vitro evaluations. Tau and Taxol bind to the beta tubulin site in microtubules’ structure. This is of particular interest in breast cancer, as microtubules of these cancer cells are structurally distinct from some other microtubules, such as neuronal microtubules, due to their unique beta tubulin isotype distribution. The observed changes in the in vitro polymerization of breast cancer microtubules, and the different function of some molecular motors along them, leave open the possibility that the drug resistance mechanism can potentially be associated with different responses of these microtubules to Tau and Taxol. We carried out a series of parallel experiments to allow comparison of the in vitro dual effect of Tau and Taxol on the polymerization of MCF7 microtubules. We observed a concentration-dependent demotion-like alteration in the self-polymerization kinetics of Tau-induced MCF7 microtubules. In contrast, microtubules polymerized under the simultaneous effects of Tau and Taxol showed promoted assembly as compared with those observed in Tau-induced microtubules. The analysis of our data obtained from the length of MCF7 microtubules polymerized under the interaction with Tau and Taxol in vitro suggests that the phenomenon known as drug resistance in microtubule-targeted drugs such as Taxol may not be directly linked to the different responses of microtubules to the drug. The effect of the drug may be mitigated due to the simultaneous interactions with other microtubule-associated proteins such as Tau protein. The observed regulatory effect of Tau and Taxol on the polymerization of breast cancer microtubules in vitro points to additional evidence for the possible role of tubulin isotypes in microtubules’ functions.

Endophytic fungus Pseudodidymocyrtis lobariellae KL27 promotes taxol biosynthesis and accumulation in Taxus chinensis

BACKGROUND

Taxol from Taxus species is a precious drug used for the treatment of cancer and can effectively inhibit the proliferation of cancer cells. However, the growth of Taxus plants is very slow and the content of taxol is quite low. Therefore, it is of great significance to improve the yield of taxol by modern biotechnology without destroying the wild forest resources. Endophytic fungus which symbiosis with their host plants can promote the growth and secondary metabolism of medicinal plants.

RESULTS

Here, an endophytic fungus KL27 was isolated from T. chinensis, and identified as Pseudodidymocyrtis lobariellae. The fermentation broth of KL27 (KL27-FB) could significantly promote the accumulation of taxol in needles of T. chinensis, reaching 0.361 ± 0.082 mg/g·DW (dry weight) at 7 days after KL27-FB treatment, which is 3.26-fold increase as compared to the control. The RNA-seq and qRT-PCR showed that KL27-FB could significantly increase the expression of key genes involved in the upstream pathway of terpene synthesis (such as DXS and DXR) and those in the taxol biosynthesis pathway (such as GGPPS, TS, T5OH, TAT, T10OH, T14OH, T2OH, TBT, DBAT and PAM), especially at the early stage of the stimulation. Moreover, the activation of jasmonic acid (JA) biosynthesis and JA signal transduction, and its crosstalk with other hormones, such as gibberellin acid (GA), ethylene (ET) and salicylic acid (SA), explained the elevation of most of the differential expressed genes related to taxol biosynthesis pathway. Moreover, TF (transcriptional factor)-encoding genes, including MYBs, ethylene-responsive transcription factors (ERFs) and basic/helix-loop-helix (bHLH), were detected as differential expressed genes after KL27-FB treatment, further suggested that the regulation of hormone signaling on genes of taxol biosynthesis was mediated by TFs.

CONCLUSIONS

Our results indicated that fermentation broth of endophytic fungus KL27-FB could effectively enhance the accumulation of taxol in T. chinensis needles by regulating the phytohormone metabolism and signal transduction and further up-regulating the expression of multiple key genes involved in taxol biosynthesis. This study provides new insight into the regulatory mechanism of how endophytic fungus promotes the production and accumulation of taxol in Taxus sp.

Pacific Blue-Taxoids as Fluorescent Molecular Probes of Microtubules

Taxoids such as paclitaxel (Taxol) are an important class of anticancer drugs that bind β-tubulin and stabilize cellular microtubules. To provide new chemical tools for studies of microtubules, we synthesized derivatives of paclitaxel modified at the 7-position with the small coumarin-derived fluorophore Pacific Blue (PB). Three of these Pacific Blue-Taxoids termed PB-Gly-Taxol, PB-β-Ala-Taxol, and PB-GABA-Taxol bind purified crosslinked microtubules with affinities of 34-265 nM, where the affinity can be tuned based on the length of an amino acid linker. When added to living cells in the presence of verapamil or probenecid as inhibitors of efflux, these compounds allow visualization of the microtubule network by confocal microscopy. We describe methods for the synthesis of these probes, determination of their affinities for crosslinked tubulin, and imaging of microtubules in living HeLa cells. We further describe their uptake by Caco-2 cells and two transporter-deficient Caco-2 knockout cell lines in the absence and presence of efflux inhibitors by flow cytometry. These studies revealed that p-glycoprotein (MDR1) and multidrug-resistance protein 2 (MRP2) are major mediators of efflux of these molecular probes. These compounds provide useful tools for studies of microtubules and cellular efflux transporters in living cells.

Boosting the Anticancer Activity of Aspergillus flavus "endophyte of Jojoba" Taxol via Conjugation with Gold Nanoparticles Mediated by γ-Irradiation

Taxol production by fungi is one of the promising alternative approaches, regarding to the natural and semisynthetic sources; however, the lower yield and rapid loss of Taxol productivity by fungi are the major challenges that halt their further industrial implementation. Thus, searching for fungal isolates with affordable Taxol-production stability, in addition to enhance its anticancer activity via conjugation with gold nanoparticles, is the main objectives of this study. Twenty-four endophytic fungal isolates were recovered from the barks, twigs, and leaves of jojoba plant, among these fungi, Aspergillus flavus MW485934.1 was the most potent Taxol producer (88.6 µg/l). The chemical identity of the extracted Taxol of A. flavus was verified by the TLC, HPLC, HNMR, and FTIR analyses. The yield of Taxol produced by A. flavus was optimized by the response surface methodology (RSM) using Plackett-Burman (PBD) and faced central composite designs (FCCD). The yield of Taxol by A. flavus was increased by about 3.2 folds comparing to the control cultures (from 96.5 into 302.7 µg/l). The highest Taxol yield by was obtained growing A. flavus on a modified malt extract medium (g/l) (malt extract 20.0, peptone 2.0, sucrose 20.0, soytone 2.0, cysteine 0.5, glutamine 0.5, and beef extract 1.0 adjusted to pH 6.0) and incubated at 30 °C for 16 days. From the FCCD design, the significant variables affecting Taxol production by A. flavus were cysteine, pH, and incubation time. Upon A. flavus γ-irradiation at 1.0 kGy, the Taxol yield was increased by about 1.25 fold (375.9 µg/l). To boost its anticancer activity, the purified Taxol was conjugated with gold nanoparticles (AuNPs) mediated by γ-rays irradiation (0.5 kGy), and the physicochemical properties of Taxol-AuNPs composite were evaluated by UV-Vis, DLS, XRD, and TEM analyses. The IC₅₀ values of the native-Taxol and Taxol-AuNPs conjugates towards HEPG-2 cells were 4.06 and 2.1 µg/ml, while the IC₅₀ values against MCF-7 were 6.07 and 3.3 µg/ml, respectively. Thus, the anticancer activity of Taxol-AuNPs composite was increased by 2 folds comparing to the native Taxol towards HEPG-2 and MCF-7 cell lines. Also, the antimicrobial activity of Taxol against the multidrug resistant bacteria was dramatically increased upon conjugation with AuNPs comparing to authentic AuNPs and Taxol, ensuring the higher solubility, targetability, and efficiency of Taxol upon AuNPs conjugation.

Effects and mechanisms of FBXO31 on Taxol chemoresistance in esophageal squamous cell carcinoma

Taxol is commonly used chemotherapy regimen for esophageal squamous cell carcinoma (ESCC). Study of the underlying mechanisms of Taxol chemoresistance provides better understanding of esophageal cancer treatment and may provide a rational molecular target for diagnosis and intervention. Here we showed FBXO31, which was reported to be highly expressed in ESCC and significantly associated with poor prognosis, could regulate ESCC chemosensitivity to Taxol. Silencing of FBXO31 in ESCC cells sensitized cells to Taxol treatment, evidenced by FACS analysis and TUNEL assay, showing as an increased apoptotic population in FBXO31-knockdown cells compared to the control cells. The mass spectrometry data and coimmunoprecipitation results showed FBXO31 could bind with cofilin-1. Cofilin-1 knockdown in FBXO31-overexpression cells reversed FBXO31-induced suppression of cell apoptosis, suggesting FBXO31-mediated Taxol chemoresistance is associated with cofilin-1. Furthermore, in vivo experiments confirmed that knockdown of FBXO31 sensitized ESCC to Taxol treatment. This finding substantiated a pivotal role of FBOX31 in ESCC chemoresistance, indicating that FBXO31 may be a potential indicator or target for drug resistance in ESCC.

Lattice defects induced by microtubule-stabilizing agents exert a long-range effect on microtubule growth by promoting catastrophes

Microtubules are major cytoskeletal filaments important for cell division, growth, and differentiation. Microtubules can rapidly switch between phases of growth and shortening, and this dynamic behavior is essential for shaping microtubule arrays. To obtain insights into mechanisms controlling microtubule dynamics, here we used microtubule-stabilizing agents such as Taxol and their fluorescent analogs to manipulate microtubule protofilament number and generate stable defects in microtubule lattices that can be visualized using fluorescence microscopy. We show that microtubule polymerization rate increases with protofilament number and that drug-induced microtubule lattice discontinuities can promote plus-end catastrophes at a distance of several micrometers. Our data indicate that structural defects in the microtubule wall can have long-range propagating effects on microtubule tip dynamics.

Microtubules are dynamic cytoskeletal polymers that spontaneously switch between phases of growth and shrinkage. The probability of transitioning from growth to shrinkage, termed catastrophe, increases with microtubule age, but the underlying mechanisms are poorly understood. Here, we set out to test whether microtubule lattice defects formed during polymerization can affect growth at the plus end. To generate microtubules with lattice defects, we used microtubule-stabilizing agents that promote formation of polymers with different protofilament numbers. By employing different agents during nucleation of stable microtubule seeds and the subsequent polymerization phase, we could reproducibly induce switches in protofilament number and induce stable lattice defects. Such drug-induced defects led to frequent catastrophes, which were not observed when microtubules were grown in the same conditions but without a protofilament number mismatch. Microtubule severing at the site of the defect was sufficient to suppress catastrophes. We conclude that structural defects within the microtubule lattice can exert effects that can propagate over long distances and affect the dynamic state of the microtubule end.

Mechanisms of influence of the microtubule over-stabilizing ligands on the structure and intrinsic dynamics of α,β-Tubulin

The intervention into the cell cycle progression by administering microtubule over-stabilizing ligands that arrest the mitotic cell division by preventing spindle dissociation, is a promising strategy to fight against cancers. The building blocks of the microtubules and the spindles, i.e. the α,β-tubulin dimer, upon binding of such ligands, stay more comfortably in the microtubular multimeric form; the phenomenon of which is the key to the said over-stabilization. Using two such over-stabilizing ligands, Taxol and Taxotere, the present work reports the collective changes that these ligands induce on the structure and dynamics of the α,β-tubulin dimer which could be reconciled as the molecular basis of the over-stabilization of the microtubules; the trends have been found to be statistically significant across all independent calculations on them. The ligand binding increases the coherence between the residue communities of the two opposite faces of the β-subunit, which in a periodic arrangement in microtubule are knwon to form intermolecular contact with each other. This is likely to create an indirect cooperativity between those structural regions and this is a consequence of the reshuffling of the internal network of interactions upon ligand binding. Such reorganizations are also complemented by the increased contributions of the softer modes of the intrinsic dynamics more, which is likely to increase the plasticity of the system favourable for making structural adjustments in a multimer. Further, the ligands are able to compensate the drawback of lacking one phosphate group in protein-GDP interactions compared to the same for protein-GTP and this is in agreement with the hints form the earlier reports. The findings form a mechanistic basis of the enhanced capacity of the α,β-tubulin dimer to get more favourably accommodated into the microtubule superstructure upon binding either of Taxol and Taxotere.

The combined therapy of miR-383-5p restoration and paclitaxel for treating MDA-MB-231 breast cancer

The deregulation of microRNAs (miRs) has been identified in tumor development. Indeed, the restoration of tumor-suppressive miRs has been associated with inhibited tumor development in various cancers. Herein, we aimed to evaluate the impact of combined miR-383-5p restoration, as a tumor-suppressive miR, with taxol therapy in suppressing MDA-MB-231 breast cancer development. MDA-MB-231 cell line was restored with miR-383-5p and treated with paclitaxel both in combined and separate manners. The MTT experiment was carried out to measure the cytotoxicity of the therapeutic approaches on the tumoral cells. Besides, flow cytometry was conducted to assess apoptosis and cell cycle status following the treatments. Furthermore, the expression levels of critical factors contributed to tumor proliferation, migration, apoptosis were investigated via the qRT-PCR and western blotting techniques. The outcomes pointed out that the miR-383-5p might substantially enhance the chemosensitivity of MDA-MB-231 to taxol. Besides, miR-383-5p restoration and the combined therapy of miR-383-5p restoration with paclitaxel could remarkably increase apoptosis, decrease cell viability, arrest the cell cycle, inhibit clonogenicity, suppress tumor migration, suppress the PI3K/Akt signaling pathway, and down-regulate PD-L1 expression of BC cells. The restoration of miR-383-5p can enhance the chemosensitivity of MDA-MB-231 cells to taxol. Despite the anti-tumoral effects of miR-383-5p restoration on MDA-MB-231 breast cancer development, the combined therapy of miR-383-5p restoration with paclitaxel can be more effective in repressing MDA-MB-231 breast cancer development.

Taxanes and taxoids of the genus Taxus - A comprehensive inventory of chemical diversity

The pseudoalkaloid diterpene Taxol® (paclitaxel) emerged as a best-selling anti-cancer drug in the mid-1990s. The compound attracted considerable interest because of its unique mechanism to stabilize microtubules, thus reducing dynamicity and ultimately promoting mitotic arrest. Taxol was originally isolated from members of the genus Taxus. Over the last 50 years, close to 600 metabolites with taxane scaffolds were isolated from various Taxus species and their structures reported. The present review article provides an overview of the known chemical diversity of taxanes, with an emphasis on the functionalization of diterpene scaffolds. The implications of the occurrence of chemically diverse taxane metabolites for unraveling Taxol biosynthesis and enabling pathway engineering are discussed as well.

The mTORC1/S6K/PDCD4/eIF4A Axis Determines Outcome of Mitotic Arrest

mTOR is a serine/threonine kinase and a master regulator of cell growth and proliferation. Raptor, a scaffolding protein that recruits substrates to mTOR complex 1 (mTORC1), is known to be phosphorylated during mitosis, but the significance of this phosphorylation remains largely unknown. Here we show that raptor expression and mTORC1 activity are dramatically reduced in cells arrested in mitosis. Expression of a non-phosphorylatable raptor mutant reactivates mTORC1 and significantly reduces cytotoxicity of the mitotic poison Taxol. This effect is mediated via degradation of PDCD4, a tumor suppressor protein that inhibits eIF4A activity and is negatively regulated by the mTORC1/S6K pathway. Moreover, pharmacological inhibition of eIF4A is able to enhance the effects of Taxol and restore sensitivity in Taxol-resistant cancer cells. These findings indicate that the mTORC1/S6K/PDCD4/eIF4A axis has a pivotal role in the death versus slippage decision during mitotic arrest and may be exploited clinically to treat tumors resistant to anti-mitotic agents.

Tracing of intracellular pH in cancer cells in response to Taxol treatment

Genetically encoded pH-sensors are the promising instrument for intracellular pH (pHi) registration. In tumor tissue the reversed pH gradient is known to be the important hallmark of cancer and regulator of tumor response on chemotherapy. However the effect of chemotherapeutic drugs on the pHi of tumor cells is largely unknown. Here we using genetically encoded ratiometric pH-sensor SypHer2 were able to monitor pHi in vitro in cell monolayer and tumor spheroids and in vivo in tumor xenografts. In tumor cell monolayer different pHi dynamic was revealed in the dying cell and division-arrested surviving cells. The treatment effect of taxol varied in monolayer and tumor spheroids and pHi changes were able to reflect these difference. The tend to pHi decrease in respect to taxol in vivo matched with results obtained for the cell monolayer. Also in both cases the cell cycle-arrest was the main treatment effect in contrast to tumor spheroid, where the cell death was the primary result. These findings elucidate the significance of pHi in the mechanisms of taxol action on cervical cancer cells and will be valuable for development of new approaches for cancer treatment.

Triggering the biosynthetic machinery of Taxol by Aspergillus flavipes via cocultivation with Bacillus subtilis: proteomic analyses emphasize the chromatin remodeling upon fungal-bacterial interaction

Attenuating the Taxol biosynthesis by fungi with storage and subculturing is the major challenge that limits their further industrial applications. Aspergillus flavipes has been reported as a potent Taxol producer, with plausible increasing to its Taxol yield upon coculturing with the microbiome of Podocarpus gracilior (El-Sayed et al., Process Biochemistry 76:55-67, 2019a; Scientific Reports 9, 2019b; Enzyme and Microbial Technology 131, 2019c); however, the identity of these microbial inducers remains ambiguous. Thus, this study was to assess the potency of individual microbes to trigger the Taxol biosynthesis by A. flavipes and to unravel the differentially expressed protein in response to bacterial interaction. Among the 25 bacterial endophytes of P. gracilior, Bacillus subtilis was the potent isolate enhancing the Taxol yield of A. flavipes by ~1.6-fold. Strikingly, this bacterial elicitor displayed a reliable inhibition to the growth of A. flavipes, so the released antifungal compound by B. subtilis could be the same signals for triggering the expression of A. flavipes Taxol synthesis. The highest Taxol yield by A. flavipes was obtained with the viable cells of B. subtilis, ensuring the pivotality of physical intimate bacterial-fungal interaction. Differential proteome of the cocultures A. flavipes and B. subtilis as well as the axenic A. flavipes was conducted by LC-MS/MS. From the total of 106 identified proteins, 50 proteins were significantly expressed, 47 were upregulated ones, and 59 were downregulated ones for the cocultures normalizing to the axenic one. From the Gene Ontology (GO) and KEGG enrichment analyses, the cellular process, primary metabolic process, and nitrogen compound metabolic process were significantly changed in the coculture normalizing to monoculture of A. flavipes. The molecular function terms (histones H2B, H2A, peptidyl-prolyl cis-trans isomerase, and nucleoside-diphosphate kinase (NDPK)) were the highly significantly expressed proteins of A. flavipes in response to B. subtilis, with strong correlation to triggering of Taxol biosynthesis. The intimate interaction of A. flavipes with B. subtilis strongly modulates the Taxol biosynthetic machinery of A. flavipes by modulating the chromatin remodeling.

Evaluating the genetic basiss of anti-cancer property of Taxol in Saccharomyces cerevisiae model

Taxol has been regarded as one of the most successful anti-cancer drugs identified from natural sources to date. Although Taxol is known to sensitize cells by stabilizing microtubules, its ability to cause DNA damage in peripheral blood lymphocytes and to induce oxidative stress and apoptosis indicates that Taxol may have other modes of cytotoxic action. This study focuses on identifying the additional targets of Taxol that may contribute to its multifaceted cell killing property, using Saccharomyces cerevisiae. We show that yeast oxidative stress response mutants (sod1Δ, tsa1Δ and cta1Δ) and DNA damage response mutants (mre11∆, sgs1∆ and sub1∆) are highly sensitive to Taxol. Our results also show that Taxol increases the level of reactive oxygen species (ROS) in yeast oxidative stress response mutant strains. Further, 4',6-Diamidino-2'-phenylindole (DAPI) and acridine orange/ethidium bromide (AO/EB) staining show that Taxol induces apoptotic features such as nuclear fragmentation and chromatin condensation in DNA repair mutants. On the whole, our results suggest that Taxol's cytotoxic property is attributed to its multifaceted mechanism of action. Yeast S. cerevisiae anti-oxidant and DNA repair gene mutants are sensitive to Taxol compared to wild-type, suggesting yeast model can be used to identify the genetic targets of anti-cancer drugs.

MUC1 regulates AKT signaling pathway by upregulating EGFR expression in ovarian cancer cells

MUC1, a type I transmembrane glycoprotein, mediates tumor growth and cellular differentiation in various types of cancers. However, the mechanism of MUCI in ovarian cancer has not been fully clarified. In our study, we have observed that MUC1 can play a crucial role in the development and progression of ovarian cancer and act as a predictive marker. We also found that MUC1 could increase the expression of EGFR, and MUC1-EGFR co-administration could promote the cellular growth via the AKT pathway. Taxol is an important drug for treating ovarian cancer, which can prevent cancer recurrence and reduce mortality. Our data have collectively reflected that Taxol can prevent ovarian cancer with abnormal expression of MUC1.

Production, bioprocess optimization and γ-irradiation of Penicillium polonicum, as a new Taxol producing endophyte from Ginko biloba

Twenty-eight fungal endophytes were recovered from the different parts of Ginkgo biloba and screened for their Taxol producing potency. Among these isolates, Penicillium polonicum AUMC14487 was reported as the potent Taxol producer (90.53 μg/l). The chemical identity of the extracted Taxol was verified from the TLC, HPLC, NMR, EDX, and FTIR analyses. The extracted Taxol displayed a strong antiproliferative activity against HEPG2 (IC₅₀ 4.06 μM) and MCF7 (IC₅₀ 6.07 μM). The yield of Taxol by P. polonicum was optimized by nutritional optimization with the Response Surface Methodology (RSM) using Plackett-Burman and Central Composite Designs. In addition to nutritional optimization, the effect of γ-irradiation of the spores of P. polonicum on its Taxol producing potency was evaluated. The yield of Taxol by P. polonicum was increased via nutritional optimization by response surface methodology with Plackett-Burman and FCCD designs, and γ-irradiation by about 4.5 folds, comparing to the control culture. The yield of Taxol was increased by about 1.2 folds (401.2 μg/l) by γ -irradiation of the isolates at 0.5-0.75 kGy, comparing to the control cultures (332.2 μg/l). The highest Taxol yield was obtained by growing P. polonicum on modified Czapek's- Dox medium (sucrose 40.0 g/l, malt extract 20.0 g/l, peptone 2.0 g/l, K₂PO₄ 2.0 g/l, KCl 1.0 g/l, NaNO₃ 2.0 g/l, MgSO₄. 5H₂O 1.0 g/l) of pH 7.0 at 30.0 °C for 7.0 days. From the FCCD design, sucrose, malt extract and incubation time being the highest significant variables medium components affecting the Taxol production by P. polonicum.

Actin and Microtubules Differently Contribute to Vacuolar Targeting Specificity during the Export from the ER

Plants rely on both actin and microtubule cytoskeletons to fine-tune sorting and spatial targeting of membranes during cell growth and stress adaptation. Considerable advances have been made in recent years in the comprehension of the relationship between the trans-Golgi network/early endosome (TGN/EE) and cytoskeletons, but studies have mainly focused on the transport to and from the plasma membrane. We address here the relationship of the cytoskeleton with different endoplasmic reticulum (ER) export mechanisms toward vacuoles. These emergent features of the plant endomembrane traffic are explored with an in vivo approach, providing clues on the traffic regulation at different levels beyond known proteins’ functions and interactions. We show how traffic of vacuolar markers, characterized by different vacuolar sorting determinants, diverges at the export from the ER, clearly involving different components of the cytoskeleton.

Importation of taxadiene synthase into chloroplast improves taxadiene production in tobacco

MAIN CONCLUSION

Importation of taxadiene synthase into chloroplasts is important for the efficient heterologous production of taxadiene. Taxadiene, the first committed precursor to taxol, is synthesized from geranylgeranyl pyrophosphate (GGPP) by action of taxadiene synthase (TS). Heterologous production of taxadiene could potentially rely on both cytosolic mevalonic acid (MVA) pathway and the plastidic methylerythritol phosphate (MEP) pathway. We suggest the compartmentalized engineering in chloroplast as an efficient approach for taxadiene production. In this study, we directly introduced the TS gene from Taxus brevifolia into the tobacco chloroplast genome and found that the transplastomic plants accumulated a low content of taxadiene, ~ 5.6 μg/g dry weight (DW). Moreover, we tried a combination of MEP and MVA pathways for taxadiene synthesis by nuclear transformation with a truncated version of TS (without encoding a transit peptide) into the transplastomic plants. However, this did not further improve the taxadiene production. In contrast, we found that taxadiene could be produced up to 87.8 μg/g DW in leaves of transgenic plants expressing TS with a chloroplast transit peptide, which was significantly higher than that in leaves of transplastomic plants. Thus, this study highlights the importance of TS importation into chloroplast for production of taxadiene.

Blocking miR-27a-3p sensitises Taxol resistant osteosarcoma cells through targeting Fbxw7

Osteosarcoma (OS) is a human malignancy, which primarily affects the long bones and occurs in children and adolescent. Although advanced clinical approaches and the addition of neoadjuvant chemotherapy improved 5-year survival of OS patients, a large fraction of them developed chemoresistance. Thus, due to the high morbidity and mortality of OS, it is urgent to investigate effectively molecular targets against chemoresistant osteosarcoma. In this study, we aimed to evaluate the functions of miR-27a-3p in the Taxol sensitivity of osteosarcoma. From fifty-paired OS tumour tissues and adjacent normal bone tissues, we detected significantly upregulated miR-27a-3p expressions in osteosarcoma. In addition, expression of miR-27a-3p was remarkedly elevated in OS cancer cell lines compared with normal osteoblast cells, hFOB1.19. Blocking miR-27a-3p effectively suppressed OS cell growth and sensitised OS cells to Taxol. miRNA target prediction indicated Fbxw7 was a potential target of miR-27a-3p. We demonstrated Fbxw7 functioned as a tumour suppressor in osteosarcoma. Overexpression of miR-27a-3p significantly suppressed Fbxw7 protein expression in OS cells. The direct binding between miR-27a-3p and Fbxw7 3'UTR was validated by luciferase assay. Particularly, results from rescue experiments by inhibiting Fbxw7 expressions in miR-23a-3p-blocked OS cells demonstrated the miR-27a-3p-mediated Taxol resistance was through direct targeting Fbxw7. In summary, our findings report a new molecular mechanism for the miR-27a-3p-mediated Taxol resistance via targeting tumour suppressor, Fbxw7 in osteosarcoma. This study potentiates a miRNA-based therapeutic approach against Taxol resistant osteosarcoma.

Effects of taxol on neuronal differentiation of postnatal neural stem cells cultured from mouse subventricular zone

Taxol (paclitaxel), a chemotherapeutic agent for several cancers, can adversely affect the peripheral nervous system. Recently, its negative impact on cognitive function in cancer patients has become evident. In rodents, taxol impaired learning and memory, with other possible negative effects on the brain. In this study, we investigated the effects of taxol on cultured neural stem cells (NSCs) from the mouse neurogenic region, the subventricular zone (SVZ). Taxol significantly decreased both proliferation and neuronal differentiation of NSCs. Transient treatment with taxol for one day during a 4-day differentiation greatly decreased neurogenesis along with an abnormal cell cycle progression. Yet, taxol did not kill differentiated Tuj1+ neurons and those neurons had longer neurites than neurons under control conditions. For glial differentiation, taxol significantly reduced oligodendrogenesis as observed by immunostaining for Olig2 and O4. However, differentiation of astrocytes was not affected by taxol. In contrast, differentiated oligodendrocytes were extremely sensitive to taxol. Almost no Olig2-positive cells were observed after three days of treatment with taxol. Taxol has distinct effects on neurons and glial cells during their production through differentiation from NSCs as well as post-differentiation. Thus, we suggest that taxol might interfere with neurogenesis of NSCs possibly through a disturbance in the cell cycle and may eliminate differentiated oligodendrocytes.

Trichostatin A sensitizes hepatoma cells to Taxol more than 5-Aza-dC and dexamethasone

OBJECTIVES

This work was designed to compare the sensitizing effects of epigenetic modifiers on cancer cells vs. that of glucocorticoids. Also, to evaluate their effects on genes involved in epigenetic changes and drug metabolism.

METHODS

Hepatoma cells (HepG2) were treated with the anticancer drug (Taxol), with a histone deacetylase inhibitor (Trichostatin A [TSA]), DNA methyltransferase inhibitor (5-Aza-dC) or dexamethasone (DEX). Cytotoxicity was assessed by MTT assay and the apoptosis was determined by Annexin V-FITC. The expression levels of HDAC1, HDAC3, Dnmt1, Dnmt3α, CYP1A2, CYP3A4, CYP2B6, CYP2C19 and CYP2D6 were monitored by qRT-PCR.

RESULTS

TSA, synergistically enhanced cells sensitivity with the anticancer effect of Taxol more than 5-Aza-dC and DEX. This was evidenced by the relative decrease in IC₅₀ in cells cotreated with Taxol + TSA, Taxol + 5-Aza-dC or Taxol + DEX. Apoptosis was induced in 51.2, 16.9 and 41.3% of cells, respectively. In presence of Taxol, TSA induced four-fold increase in the expression of HDAC1 and downregulated Dnmt1&3α genes. CYP2D6 demonstrated progressive expression (up to 28-fold) with the increasing number of drugs. Moreover, the isoform overexpressed in cells treated with TSA + Taxol > DEX + Taxol > 5-Aza-dC + Taxol (6.4, 4.6 and 2.99, respectively). The investigated genes were clustered in two distinct subsets, where no coregulation was observed between HDAC1 and HDAC3. However, tight pairwise correlation-based cluster was seen between (CYP3A4/Dnmt3α and CYP2D6/CYP2C19).

CONCLUSIONS

The data reflects the sensitizing effect of acetylation modification by TSA on the responsiveness of hepatoma cells to anticancer therapy. The effect of histone deacetylase inhibition was more than hypomethylation and glucocorticoid effects. TSA exerts its role through its modulatory role on epigenetics and drugs metabolizing genes. Other modifiers (5-Aza-dC and DEX), however may adopt different mechanisms.

Trichostatin A sensitizes hepatoma cells to Taxol more than 5-Aza-dC and dexamethasone

OBJECTIVES

This work was designed to compare the sensitizing effects of epigenetic modifiers on cancer cells vs. that of glucocorticoids. Also, to evaluate their effects on genes involved in epigenetic changes and drug metabolism.

METHODS

Hepatoma cells (HepG2) were treated with the anticancer drug (Taxol), with a histone deacetylase inhibitor (Trichostatin A [TSA]), DNA methyltransferase inhibitor (5-Aza-dC) or dexamethasone (DEX). Cytotoxicity was assessed by MTT assay and the apoptosis was determined by Annexin V-FITC. The expression levels of HDAC1, HDAC3, Dnmt1, Dnmt3α, CYP1A2, CYP3A4, CYP2B6, CYP2C19 and CYP2D6 were monitored by qRT-PCR.

RESULTS

TSA, synergistically enhanced cells sensitivity with the anticancer effect of Taxol more than 5-Aza-dC and DEX. This was evidenced by the relative decrease in IC50 in cells cotreated with Taxol + TSA, Taxol + 5-Aza-dC or Taxol + DEX. Apoptosis was induced in 51.2, 16.9 and 41.3% of cells, respectively. In presence of Taxol, TSA induced four-fold increase in the expression of HDAC1 and downregulated Dnmt1&3α genes. CYP2D6 demonstrated progressive expression (up to 28-fold) with the increasing number of drugs. Moreover, the isoform overexpressed in cells treated with TSA + Taxol > DEX + Taxol > 5-Aza-dC + Taxol (6.4, 4.6 and 2.99, respectively). The investigated genes were clustered in two distinct subsets, where no coregulation was observed between HDAC1 and HDAC3. However, tight pairwise correlation-based cluster was seen between (CYP3A4/Dnmt3α and CYP2D6/CYP2C19).

CONCLUSIONS

The data reflects the sensitizing effect of acetylation modification by TSA on the responsiveness of hepatoma cells to anticancer therapy. The effect of histone deacetylase inhibition was more than hypomethylation and glucocorticoid effects. TSA exerts its role through its modulatory role on epigenetics and drugs metabolizing genes. Other modifiers (5-Aza-dC and DEX), however may adopt different mechanisms.

The Uniqueness of Albumin as a Carrier in Nanodrug Delivery

Albumin is an appealing carrier in nanomedicine because of its unique features. First, it is the most abundant protein in plasma, endowing high biocompatibility, biodegradability, nonimmunogenicity, and safety for its clinical application. Second, albumin chemical structure and conformation allows interaction with many different drugs, potentially protecting them from elimination and metabolism in vivo, thus improving their pharmacokinetic properties. Finally, albumin can interact with receptors overexpressed in many diseased tissues and cells, providing a unique feature for active targeting of the disease site without the addition of specific ligands to the nanocarrier. For this reason, albumin, characterized by an extended serum half-life of around 19 days, has the potential of promoting half-life extension and targeted delivery of drugs. Therefore, this article focuses on the importance of albumin as a nanodrug delivery carrier for hydrophobic drugs, taking advantage of the passive as well as active targeting potential of this nanocarrier. Particular attention is paid to the breakthrough NAB-Technology, with emphasis on the advantages of Nab-Paclitaxel (Abraxane), compared to the solvent-based formulations of Paclitaxel, i.e., CrEL-paclitaxel (Taxol) in a clinical setting. Finally, the role of albumin in carrying anticancer compounds is depicted, with a particular focus on the albumin-based formulations that are currently undergoing clinical trials. The article sheds light on the power of an endogenous substance, such as albumin, as a drug delivery system, signifies the importance of the drug vehicle in drug performance in the biological systems, and highlights the possible future trends in the use of this drug delivery system.