Tubulin-targeted agents including docetaxel and cabazitaxel

Applying Spatiotemporal Modeling of Cell Dynamics to Accelerate Drug Development

Cells act as physical computational programs that utilize input signals to orchestrate molecule-level protein-protein interactions (PPIs), generating and responding to forces, ultimately shaping all of the physiological and pathophysiological behaviors. Genome editing and molecule drugs targeting PPIs hold great promise for the treatments of diseases. Linking genes and molecular drugs with protein-performed cellular behaviors is a key yet challenging issue due to the wide range of spatial and temporal scales involved. Building predictive spatiotemporal modeling systems that can describe the dynamic behaviors of cells intervened by genome editing and molecular drugs at the intersection of biology, chemistry, physics, and computer science will greatly accelerate pharmaceutical advances. Here, we review the mechanical roles of cytoskeletal proteins in orchestrating cellular behaviors alongside significant advancements in biophysical modeling while also addressing the limitations in these models. Then, by integrating generative artificial intelligence (AI) with spatiotemporal multiscale biophysical modeling, we propose a computational pipeline for developing virtual cells, which can simulate and evaluate the therapeutic effects of drugs and genome editing technologies on various cell dynamic behaviors and could have broad biomedical applications. Such virtual cell modeling systems might revolutionize modern biomedical engineering by moving most of the painstaking wet-laboratory effort to computer simulations, substantially saving time and alleviating the financial burden for pharmaceutical industries.

Suppression of N-Glycosylation of Zinc Finger Protein 471 Affects Proliferation, Invasion, and Docetaxel Sensitivity of Tongue Squamous Cell Carcinoma via Regulation of c-Myc

Zinc finger protein 471 (ZNF471) is a member of the Krüppel-related domain zinc finger protein family, and has recently attracted attention because of its anti-cancer effects. N-glycosylation regulates expression and functions of the protein. This study aimed to investigate the effects of ZNF471 N-glycosylation on the proliferation, invasion, and docetaxel sensitivity of tongue squamous cell carcinoma (TSCC). It analyzed the expression, function, and prognostic significance of ZNF471 in TSCC using bioinformatics techniques such as gene differential expression analysis, univariate Cox regression analysis, functional enrichment analysis, and gene set enrichment analysis. Using site-specific mutagenesis, this study generated three mutant sites for ZNF471 N-glycosylation to determine the effect of N-glycosylation on ZNF471 protein levels and function. Quantitative real-time PCR, Western blot analysis, and immunohistochemistry tests confirmed the down-regulation of ZNF471 expression in TSCC. Low expression of ZNF471 is associated with poor prognosis of patients with TSCC. Overexpression of ZNF471 in vitro retarded the proliferation of TSCC cells and suppressed cell invasion and migration ability. Asparagine 358 was identified as a N-glycosylation site of ZNF471. Suppressing N-glycosylation of ZNF471 enhanced the protein stability and promoted the translocation of protein to the cell nucleus. ZNF471 binding to c-Myc gene promoter suppressed oncogene c-Myc expression, thereby playing the anti-cancer effect and enhancing TSCC sensitivity to docetaxel. In all, N-glycosylation of ZNF471 affects the proliferation, invasion, and docetaxel sensitivity of TSCC via regulation of c-Myc.

Synthesis and Anticancer Activity of Ergosterol Peroxide Hybrids With Paclitaxel Side Chain Inducing Apoptosis in Human Hepatoma Carcinoma Cells

The antitumor activities of natural paclitaxel (PTX), semisynthetic docetaxel, and cabazitaxel are highly dependent on their C-13 side chains. Therefore, using natural ergosterol peroxide (EP, 1) as the lead compound, two EP-PTX hybrids (EP-A2 and EP-B2) were prepared and their antitumor activities were evaluated against 4 kinds of human MCF-7, HepG2, HCT-116, and A549 cell lines in vitro. The results showed that both EP-A2 and EP-B2 inhibited the growth of all four kinds of tested tumor cell lines. For paclitaxel-resistant MCF-7 cells, both EP-A2 and EP-B2 showed significant inhibitory activity with relatively low IC50 values (9.39 μM and 8.60 μM, respectively). In addition, EP-B2 inhibited the growth of the HepG2 cells (IC50 = 7.82 μM) more successfully than EP. Preliminary studies of the mechanism suggest that EP-B2 could arrest the G1 phase transition in HepG2 cells. In addition, EP-B2 showed an obvious apoptosis-inducing effect in HepG2 cells, as detected by the Annexin V/PI binding assay and the Western blot assay. Hybrid EP-B2 has the potential to become a novel antitumor drug through further study of the mechanism of action and its structural modifications.

Small-molecule inhibitors, immune checkpoint inhibitors, and more: FDA-approved novel therapeutic drugs for solid tumors from 1991 to 2021

The United States Food and Drug Administration (US FDA) has always been a forerunner in drug evaluation and supervision. Over the past 31 years, 1050 drugs (excluding vaccines, cell-based therapies, and gene therapy products) have been approved as new molecular entities (NMEs) or biologics license applications (BLAs). A total of 228 of these 1050 drugs were identified as cancer therapeutics or cancer-related drugs, and 120 of them were classified as therapeutic drugs for solid tumors according to their initial indications. These drugs have evolved from small molecules with broad-spectrum antitumor properties in the early stage to monoclonal antibodies (mAbs) and antibody‒drug conjugates (ADCs) with a more precise targeting effect during the most recent decade. These drugs have extended indications for other malignancies, constituting a cancer treatment system for monotherapy or combined therapy. However, the available targets are still mainly limited to receptor tyrosine kinases (RTKs), restricting the development of antitumor drugs. In this review, these 120 drugs are summarized and classified according to the initial indications, characteristics, or functions. Additionally, RTK-targeted therapies and immune checkpoint-based immunotherapies are also discussed. Our analysis of existing challenges and potential opportunities in drug development may advance solid tumor treatment in the future.

A new flavonoid derivative exerts antitumor effects against androgen-sensitive to cabazitaxel-resistant prostate cancer cells

BACKGROUND

Our previous report has shown that the flavonoid 2'-hydroxyflavanone (2'-HF) showed inhibition of androgen receptor (AR) activity against androgen-sensitive prostate cancer (PCa) cells, LNCaP, and exhibited antitumor effects against androgen-insensitive PCa cells, PC-3, and DU145. In the present study, we prepared a derivative of 2'-HF, 16MS7F1924, and confirmed the effects of this derivative on PCa cells.

METHODS

The antiproliferation effects of 16MS7F1924 were investigated in PCa cells using LNCaP, PC-3, DU145 and docetaxel-resistant and cabazitaxel-resistant cell lines of PC-3-TxR/CxR and DU145-TxR/CxR. Prostate-specific antigen (PSA) and AR expression level in whole cells and the nucleus were confirmed in LNCaP by reverse transcriptase polymerase chain reaction and Western blot analysis. AR activity in LNCaP cells was confirmed by luciferase assay using PSA promoter-driven reporter. To analyze the antiproliferative effects, cell-based assays using flow cytometry, immunocytochemistry, and TUNEL assay as well as Western blot analysis were employed. Furthermore, PC-3, DU145 and each chemoresistant strain of human PCa cells were subcutaneously xenografted. The antitumor effects of 16MS7F1924 were evaluated in vivo.

RESULTS

16MS7F1924 showed antitumor effect on all PCa cells in a dose-dependent manner. 16MS7F1924 reduced the expression of PSA messenger RNA (mRNA) and protein and inhibited AR activity in a dose-dependent manner, while expression of AR protein and mRNA was reduced by 16MS7F1924. 16MS7F1924 induced mitotic catastrophe and apoptosis. Apoptotic cells were increased in a dose-dependent manner, and the apoptosis was mediated through the Akt pathway. Tumor growth was safely and significantly inhibited by both intraperitoneal and oral administration of 16MS7F1924 in vivo.

CONCLUSION

16MS7F1924 had sufficient antitumor activity against androgen-sensitive and cabazitaxel-resistant PCa cells and may be useful as a novel therapeutic agent overcoming hormone- and chemoresistant PCas.

Extracellular vesicles in cancer nanomedicine

To date, a lot of nanotechnological optitions are available for targeted drug delivery. Extracellular vesicles (EVs) are membrane structures that cells use for storage, transport, communication, and signaling. Recent research has focused on EVs as natural nanoparticles for drug delivery. This review sheds light on the application of EVs in cancer therapy, such as targeted chemotherapy, gene therapy, and vaccine development. Aspects of biogenesis, isolation, targeting, and loading of EVs are discussed in detail.

Harnessing the potential of multimodal radiotherapy in prostate cancer

Radiotherapy in combination with androgen deprivation therapy (ADT) is a standard treatment option for men with localized and locally advanced prostate cancer. However, emerging clinical evidence suggests that radiotherapy can be incorporated into multimodality therapy regimens beyond ADT, in combinations that include chemotherapy, radiosensitizing agents, immunotherapy and surgery for the treatment of men with localized and locally advanced prostate cancer, and those with oligometastatic disease, in whom the low metastatic burden in particular might be treatable with these combinations. This multimodal approach is increasingly recognized as offering considerable clinical benefit, such as increased antitumour effects and improved survival. Thus, radiotherapy is becoming a key component of multimodal therapy for many stages of prostate cancer, particularly oligometastatic disease.

A review of research progress of antitumor drugs based on tubulin targets

Microtubules exist in all eukaryotic cells and are one of the critical components that make up the cytoskeleton. Microtubules play a crucial role in supporting cell morphology, cell division, and material transport. Tubulin modulators can promote microtubule polymerization or cause microtubule depolymerization. The modulators interfere with the mitosis of cells and inhibit cell proliferation. Tubulin mainly has three binding domains, namely, paclitaxel, vinca and colchicine binding domains, which are the best targets for the development of anticancer drugs. Currently, drugs for tumor therapy have been developed for these three domains. However, due to its narrow therapeutic window, poor selectivity, and susceptibility to drug resistance, it has severely limited clinical applications. The method of combined medication, the change of administration method, the modification of compound structure, and the research and development of new targets have all changed the side effects of tubulin drugs to a certain extent. In this review, we briefly introduce a basic overview of tubulin and the main mechanism of anti-tumor. Secondly, we focus on the application of drugs which developed based on the three domains of tubulin to various cancers in various fields. Finally, we further provide the development progress of tubulin inhibitors currently in clinical trials.

α3β1 Integrin-Targeting Polymersomal Docetaxel as an Advanced Nanotherapeutic for Nonsmall Cell Lung Cancer Treatment

Docetaxel (DTX) widely used for treating nonsmall cell lung cancer (NSCLC) patients is associated with dose-limiting side effects, especially neurotoxicity and myelosuppression. Here, we have developed cyclic cNGQGEQc peptide-directed polymersomal docetaxel (cNGQ-PS-DTX) as a targeted and multifunctional formulation for NSCLC. cNGQ-PS-DTX carrying 8.1 wt % DTX had a size of 93 nm, neutral surface charge, high stability, and glutathione-triggered DTX release behavior. Cytotoxicity studies demonstrated a clearly better antitumor activity of cNGQ-PS-DTX in α3β1 integrin overexpressing A549 human lung cancer cells than free DTX and nontargeted PS-DTX. cNGQ-PS-DTX showed a remarkably high tolerability (over 8 times better than free DTX) and slow elimination in mice. Importantly, cNGQ-PS-DTX exhibited greatly improved tumor accumulation and higher suppression of subcutaneous and orthotopic A549 xenografts as compared to PS-DTX and free DTX controls. α3β1 integrin-targeting polymersomal docetaxel emerges as an advanced nanotherapeutic for NSCLC treatment.

Radium-223 mechanism of action: implications for use in treatment combinations

The targeted alpha therapy radium-223 (223Ra) can prolong survival in men with castration-resistant prostate cancer (CRPC) who have symptomatic bone metastases and no known visceral metastases. Preclinical studies demonstrate that 223Ra preferentially incorporates into newly formed bone matrix within osteoblastic metastatic lesions. The emitted high-energy alpha particles induce DNA double-strand breaks that might be irreparable and lead to cell death in nearby exposed tumour cells, osteoblasts and osteoclasts. Consequently, tumour growth and abnormal bone formation are inhibited by these direct effects and by the disruption of positive-feedback loops between tumour cells and the bone microenvironment. 223Ra might also modulate immune responses within the bone. The clinical utility of 223Ra has encouraged the development of other anticancer targeted alpha therapies. A thorough understanding of the mechanism of action could inform the design of new combinatorial treatment strategies that might be more efficacious than monotherapy. On the basis of the current mechanistic knowledge and potential clinical benefits, combination therapies of 223Ra with microtubule-stabilizing cytotoxic drugs and agents targeting the androgen receptor axis, immune checkpoint receptors or DNA damage response proteins are being explored in patients with CRPC and metastatic bone disease.

Determination of Genotoxic alkyl p-toluene Sulfonates in Cabazitaxel using LC-MS Method

Introduction:

A suitable LC-MS method for the quantitative determination of genotoxic impurities such as alkyl p-toluene sulfonates in Cabazitaxel was developed. Alkyl p-toluene sulfonates were estimated by LC-MS method using Waters Symmetry C18 (75×4.6 mm), 3.5 µ column.

Materials and Methods:

Column temperature was maintained 40 °C. Injection volume was 10 µL and flow rate was set as 0.8 mL/min. Sampler temperature was maintained to 25 °C and run time was set as 25 minutes. The mobile phase was a mixture of ammonium acetate buffer and acetonitrile in 70:30(v/v) was used.

Results:

The method validation has been carried as per ICH guidelines. LOQ was found to be 2.66 µg/mL, 2.75 µg/mL and 2.55 µg/mL for MPTS, EPTS and IPPTS Alkyl p-Toluene Sulfonates (APTS) respectively.

Conclusion:

The proposed Liquid chromatography-Mass spectroscopy method that can quantify genotoxic APTS in Cabazitaxel at low-level concentration has been developed and validated as per ICH guidelines. Hence, the proposed method was recommended for the assay of genotoxic impurities of cabazitaxel in dosage forms in busy pharmaceutical laboratories.

How Cancer Cells Resist Chemotherapy: Design and Development of Drugs Targeting Protein-Protein Interactions

Background:

Resistance toward chemotherapeutics is one of the main obstacles on the way to effective cancer treatment. Personalization of chemotherapy could improve clinical outcome. However, despite preclinical significance, most of the potential markers have failed to reach clinical practice partially due to the inability of numerous studies to estimate the marker’s impact on resistance properly.

Objective:

The analysis of drug resistance mechanisms to chemotherapy in cancer cells, and the proposal of study design to identify bona fide markers.

Methods:

A review of relevant papers in the field. A PubMed search with relevant keywords was used to gather the data. An example of a search request: drug resistance AND cancer AND paclitaxel.

Results:

We have described a number of drug resistance mechanisms to various chemotherapeutics, as well as markers to underlie the phenomenon. We also proposed a model of a rational-designed study, which could be useful in determining the most promising potential biomarkers.

Conclusion:

Taking into account the most reasonable biomarkers should dramatically improve clinical outcome by choosing the suitable treatment regimens. However, determining the leading biomarkers, as well as validating of the model, is a work for further investigations.

[Study on the Metabolic Reprogramming of Lung Cancer Cells Regulated by Docetaxel Based on Metabolomics]

背景与目的

多西他赛是一种临床常用的抗肿瘤药物，是晚期非小细胞肺癌（non-small cell lung cancer, NSCLC）的一线用药。然而，多西他赛抗NSCLC作用的分子机制尚不明确。研究表明肿瘤细胞的代谢重编程在肿瘤发生发展过程中发挥重要作用。本研究旨在通过结合代谢组学分析及生物学手段来探讨多西他赛所影响的NSCLC细胞代谢通路。

方法

首先，通过CCK-8实验分析多西他赛对NSCLC细胞活力的影响，筛选合适药物浓度。接下来，通过基于气相色谱质谱联用（gas chromatography-mass spectrometry, GC-MS）的代谢组学技术分析多西他赛处理和未处理的A549和H1299细胞。并通过统计学计算得到处理组和未处理组间的差异代谢物。最后，通过蛋白质免疫印迹分析（Western blot）多西他赛对其所调控的相关代谢途径中关键酶蛋白质表达水平的影响。

结果

多西他赛可时间依赖和浓度依赖地抑制A549和H1299细胞活力。随着多西他赛处理时间延长，凋亡敏感蛋白质多聚二磷酸腺苷核糖聚合酶[Poly(ADP-)Polymerase, PARP]逐渐被激活裂解形成P89片段。代谢组学分析发现，药物处理后的A549和H1299细胞内，8种代谢物均发生显著变化，主要集中于三羧酸（tricarboxylic acid, TCA）循环代谢通路。同时，药物处理后，TCA循环关键调控酶异柠檬酸脱氢酶蛋白质表达水平显著下降。

结论

多西他赛诱导NSCLC增殖抑制及凋亡的效应可能与下调异柠檬酸脱氢酶，进而抑制三羧酸循环代谢途径有关。

Modeling Cancer Cell Growth Dynamics In vitro in Response to Antimitotic Drug Treatment

Investigating the role of intrinsic cell heterogeneity emerging from variations in cell-cycle parameters and apoptosis is a crucial step toward better informing drug administration. Antimitotic agents, widely used in chemotherapy, target exclusively proliferative cells and commonly induce a prolonged mitotic arrest followed by cell death via apoptosis. In this paper, we developed a physiologically motivated mathematical framework for describing cancer cell growth dynamics that incorporates the intrinsic heterogeneity in the time individual cells spend in the cell-cycle and apoptosis process. More precisely, our model comprises two age-structured partial differential equations for the proliferative and apoptotic cell compartments and one ordinary differential equation for the quiescent compartment. To reflect the intrinsic cell heterogeneity that governs the growth dynamics, proliferative and apoptotic cells are structured in "age," i.e., the amount of time remaining to be spent in each respective compartment. In our model, we considered an antimitotic drug whose effect on the cellular dynamics is to induce mitotic arrest, extending the average cell-cycle length. The prolonged mitotic arrest induced by the drug can trigger apoptosis if the time a cell will spend in the cell cycle is greater than the mitotic arrest threshold. We studied the drug's effect on the long-term cancer cell growth dynamics using different durations of prolonged mitotic arrest induced by the drug. Our numerical simulations suggest that at confluence and in the absence of the drug, quiescence is the long-term asymptotic behavior emerging from the cancer cell growth dynamics. This pattern is maintained in the presence of small increases in the average cell-cycle length. However, intermediate increases in cell-cycle length markedly decrease the total number of cells and can drive the cancer population to extinction. Intriguingly, a large "switch-on/switch-off" increase in the average cell-cycle length maintains an active cell population in the long term, with oscillating numbers of proliferative cells and a relatively constant quiescent cell number.

Nano-sized cytochrome P450 3A4 inhibitors to block hepatic metabolism of docetaxel

Most drugs are metabolized by hepatic cytochrome P450 3A4 (CYP3A4), resulting in their reduced bioavailability. In this study, we present the design and evaluation of bio-compatible nanocarriers trapping a natural CYP3A4-inhibiting compound. Our aim in using nanocarriers was to target the natural CYP3A4-inhibiting agent to hepatic CYP3A4 and leave drug-metabolizing enzymes in other organs undisturbed. In the design of such nanocarriers, we took advantage of the nonspecific accumulation of small nanoparticles in the liver. Specific targeting functionalization was added to direct nanocarriers toward hepatocytes. Nanocarriers were evaluated in vitro for their CYP3A4 inhibition capacity and in vivo for their biodistribution, and finally injected 24 hours prior to the drug docetaxel, for their ability to improve the efficiency of the drug docetaxel. Nanoparticles of poly(lactic-co-glycolic) acid (PLGA) with a hydrodynamic diameter of 63 nm, functionalized with galactosamine, showed efficient in vitro CYP3A4 inhibition and the highest accumulation in hepatocytes. When compared to docetaxel alone, in nude mice bearing the human breast cancer, MDA-MB-231 model, they significantly improved the delay in tumor growth (treated group versus docetaxel alone, percent treated versus control ratio [%T/C] of 32%) and demonstrated a major improvement in overall survival (survival rate of 67% versus 0% at day 55).

Mass spectrometry in the pharmacokinetic studies of anticancer natural products

In the history of medicine, nature has represented the main source of medical products. Indeed, the therapeutic use of plants certainly goes back to the Sumerian and Hippocrates and nowadays nature still represents the major source for new drugs discovery. Moreover, in the cancer treatment, drugs are either natural compounds or have been developed from naturally occurring parent compounds firstly isolated from plants and microbes from terrestrial and marine environment. A critical element of an anticancer drug is represented by its severe toxicities and, after administration, the drug concentrations have to remain in an appropriate range to be effective. Anyway, the drug dosage defined during the clinical studies could be inappropriate for an individual patient due to differences in drug absorption, metabolism and excretion. For this reason, personalized medicine, based on therapeutic drug monitoring (TDM), represents one of most important challenges in cancer therapy. Mass spectrometry sensitivity, specificity and fastness lead to elect this technique as the Golden Standard for pharmacokinetics and drug metabolism studies therefore for TDM. This review focuses on the mass spectrometry-based methods developed for pharmacokinetic quantification in human plasma of anticancer drugs derived from natural sources and already used in clinical practice. Particular emphasis was placed both on the pre-analytical and analytical steps, such as: sample preparation procedures, sample size required by the analysis and the limit of quantification of drugs and metabolites to give some insights on the clinical practice applicability. © 2015 Wiley Periodicals, Inc. Mass Spec Rev. 36:213-251, 2017.

Novel Beta-Tubulin-Immobilized Nanoparticles Affinity Material for Screening β-Tubulin Inhibitors from a Complex Mixture

In order to efficiently screen and isolate β-tubulin inhibitors, β-tubulin was immobilized on core-shell PMMA/CS (poly(methyl methacrylate)/Chitosan) nanoparticles to produce a new type of immobilized affinity material named β-tubulin-immobilized nanoparticles (β-TIN). The selectivity and adsorption performance of β-TIN were characterized using various control drugs. The β-TIN, the paclitaxel molecularly imprinted ploymers (MIP), and the C18 adsorbing material were compared for selectivity and enrichment ratio. Microtubule-targeting antitumor compounds were screened and isolated from a typical Chinese medicine, Chloranthus multistachys, by β-TIN. Three active compounds (curcolnol, zedoarofuran, and codonolactone) in Chloranthus multistachys extract were captured successfully. Microscale thermophoresis demonstrated that these three compounds strongly bind to β-tubulin, and the dissociation constants (K_d) between the three active compounds and β-tubulin were 1820 ± 0.68 nM, 1640 ± 0.52 nM, and 284 ± 1.00 nM, respectively. Moreover, the binding affinity between codonolactone and β-tubulin was greater than that between paclitaxel and β-tubulin. The antitumor activities of the three compounds were confirmed by the microtubule inhibition model, and the results showed a similar antitumor mechanism as paclitaxel. Molecular dynamics simulations were performed to preliminarily investigate the potential binding sites and the structure-activity relationship between the three active molecules and β-tubulin. Our study is the first to report the use of this novel material which is highly efficient in capturing low-content β-tubulin inhibitors from a complex mixture. The three screened compounds exhibited potential antineoplastic activity, and these lead compounds utilize a new mechanism of action with promising development prospects. Because β-TIN is easily prepared, displays excellent adsorption and selectivity for targets, and can effectively maintain the steric conformation and activities of target proteins, it will be very useful in the screening of lead compounds for different drug target proteins.

Lx2-32c, a novel semi-synthetic taxane, exerts antitumor activity against prostate cancer cells in vitro and in vivo

Tubulin has been shown to be an effective target for the development of cytotoxic agents against prostate cancer. Previously, we reported that Lx2-32c is an anti-tubulin agent with high binding affinity to tubulin. In this study, we investigated the potential of Lx2-32c to act as an effective cytotoxic agent in the treatment of prostate cancer. MTT assays showed that Lx2-32c was cytotoxic to all tested prostate cancer cell lines. The Lx2-32c-treated cells typically exhibited a rounded morphology associated with the onset of apoptosis, as evidenced by immunocytochemical staining. Human prostate cancer cell lines treated with Lx2-32c arrest in the G2/M phase of the cell cycle and the treatment is associated with an increased ratio of cells in the sub-G0/G1 phase as determined by flow cytometry. Furthermore, expression of the cleaved form of poly (ADP-ribose) polymerase in prostate cancer cell lines treated with Lx2-32c was shown by Western blotting assay. Xenograft implants of LNCaP and PC3-derived tumors in nude mice showed that Lx2-32c treatment significant inhibited tumor growth with effects equivalent to those of docetaxel. These findings demonstrate the potential of Lx2-32c as a candidate antitumor agent for the treatment of prostate cancer.

Infiltrating mast cells increase prostate cancer chemotherapy and radiotherapy resistances via modulation of p38/p53/p21 and ATM signals

Early studies indicated that mast cells in prostate tumor microenvironment might influence prostate cancer (PCa) progression. Their impacts to PCa therapy, however, remained unclear. Here we found PCa could recruit more mast cells than normal prostate epithelial cells then alter PCa chemotherapy and radiotherapy sensitivity, leading to PCa more resistant to these therapies. Mechanism dissection revealed that infiltrated mast cells could increase p21 expression via modulation of p38/p53 signals, and interrupting p38-p53 signals via siRNAs of p53 or p21 could reverse mast cell-induced docetaxel chemotherapy resistance of PCa. Furthermore, recruited mast cells could also increase the phosphorylation of ATM at ser-1981 site, and inhibition of ATM activity could reverse mast cell-induced radiotherapy resistance. The in vivo mouse model with xenografted PCa C4-2 cells co-cultured with mast cells also confirmed that mast cells could increase PCa chemotherapy resistance via activating p38/p53/p21 signaling. Together, our results provide a new mechanism showing infiltrated mast cells could alter PCa chemotherapy and radiotherapy sensitivity via modulating the p38/p53/p21 signaling and phosphorylation of ATM. Targeting this newly identified signaling may help us better suppress PCa chemotherapy and radiotherapy resistance.

Utilizing G2/M retention effect to enhance tumor accumulation of active targeting nanoparticles

In recent years, active targeting strategies by ligand modification have emerged to enhance tumor accumulation of NP, but their clinical application was strictly restricted due to the complex preparation procedures, poor stability and serious toxicity. An effective and clinical translational strategy is required to satisfy the current problems. Interestingly, the internalization of NP is intimately related with cell cycle and the expression of receptors is not only related with cancer types but also cell cycle progression. So the cellular uptake of ligand modified NP may be related with cell cycle. However, few investigations were reported about the relationship between cell cycle and the internalization of ligand modified NP. Herein, cellular uptake of folic acid (FA) modified NP after utilizing chemotherapeutic to retain the tumor cells in G2/M phase was studied and a novel strategy was designed to enhance the active targeting effect. In our study, docetaxel (DTX) notably synchronized cells in G2/M phase and pretreatment with DTX highly improved in vitro and in vivo tumor cell targeting effect of FA decorated NP (FANP). Since FA was a most common used tumor active targeting ligand, we believe that this strategy possesses broader prospects in clinical application for its simplicity and effectiveness.

Cell cycle dependent cellular uptake of zinc oxide nanoparticles in human epidermal cells

Metal oxide nanoparticles (NPs), including zinc oxide (ZnO) NPs have shown success for use as vehicles for drug delivery and targeting gene delivery in many diseases like cancer. Current anticancer chemotherapeutics fail to effectively differentiate between cancerous and normal cells. There is an urgent need to develop novel drug delivery system that can better target cancer cells while sparing normal cells and tissues. Particularly, ZnO NPs exhibit a high degree of cancer cell selectivity and induce cell death, oxidative stress, interference with the cell cycle progression and genotoxicity in cancerous cells. In this scenario, effective cellular uptake of NP seems to be crucial, which is shown to be affected by cell cycle progression. In the present study, the cytotoxic potential of ZnO NPs and the effect of different cell cycle phases on the uptake of ZnO NPs were examined in A431 cells. It is shown that the ZnO NPs led to cell death and reactive oxygen species generation and were able to induce cell cycle arrest in S and G2/M phase with the higher uptake in G2/M phase compared with other phases.

iRGD-mediated reduction-responsive DSPE–PEG/LA–PLGA–TPGS mixed micelles used in the targeted delivery and triggered release of docetaxel in cancer

Reduction-sensitive micelles with crosslinked cores were developed to load the lipophilic chemotherapeutic drug docetaxel (DTX) in order to overcome the issues of toxicity, water insolubility, and rapid metabolism of DTX.

Initial testing (stage 1) of the anti-microtubule agents cabazitaxel and docetaxel, by the pediatric preclinical testing program

BACKGROUND

Although microtubule-destabilizing agents (principally vincristine) are in common use in pediatric oncology, the microtubule-stabilizing taxanes are uncommonly used to treat childhood cancers. Cabazitaxel has been reported to have activity superior to that of docetaxel in preclinical models of multidrug-resistant adult cancers, and it was active in patients who had progressed on or after docetaxel. The PPTP conducted a comparison of these two agents against the PPTP in vitro panel and against a limited panel of solid tumor xenografts.

PROCEDURES

Cabazitaxel and docetaxel were tested against the PPTP in vitro cell line panel at concentrations from 0.01 to 0.1 μM and in vivo against a subset of the PPTP solid tumor xenograft models at a dose of 10 or 7.5 mg/kg on an every 4 days × 3 I.V. schedule.

RESULTS

In vitro, both cabazitaxel and docetaxel had similar potency (median rIC50 0.47 nM and 0.88 nM, respectively) and a similar activity profile, with Ewing sarcoma cells being significantly more sensitive to both agents. In vitro sensitivity to docetaxel inversely correlated with mRNA expression for ABCB1, but the correlation with ABCB1 expression was weaker for cabazitaxel. In vivo cabazitaxel demonstrated significantly greater activity than docetaxel in five of 12 tumor models, inducing regressions in six models compared with three models for docetaxel.

CONCLUSIONS

Cabazitaxel demonstrated superior activity compared to docetaxel. The lower cabazitaxel systemic exposure tolerated in humans compared to mice needs to be considered when extrapolating these results to the clinical setting.

Ritonavir inhibits intratumoral docetaxel metabolism and enhances docetaxel antitumor activity in an immunocompetent mouse breast cancer model

Docetaxel (Taxotere(®)) is currently used intravenously as an anticancer agent and is primarily metabolized by Cytochrome P450 3A (CYP3A). The HIV protease inhibitor ritonavir, a strong CYP3A4 inhibitor, decreased first-pass metabolism of orally administered docetaxel. Anticancer effects of ritonavir itself have also been described. We here aimed to test whether ritonavir co-administration could decrease intratumoral metabolism of intravenously administered docetaxel and thus increase the antitumor activity of docetaxel in an orthotopic, immunocompetent mouse model for breast cancer. Spontaneously arising K14cre;Brca1(F/F) ;p53(F/F) mouse mammary tumors were orthotopically implanted in syngeneic mice lacking Cyp3a (Cyp3a(-/-)) to limit ritonavir effects on systemic docetaxel clearance. Over 3 weeks, docetaxel (20 mg/kg) was administered intravenously once weekly, with or without ritonavir (12.5 mg/kg) administered orally for 5 days per week. Untreated mice were used as control for tumor growth. Ritonavir treatment alone did not significantly affect the median time of survival (14 vs. 10 days). Median time of survival in docetaxel-treated mice was 54 days. Ritonavir co-treatment significantly increased this to 66 days, and substantially reduced relative average tumor size, without altering tumor histology. Concentrations of the major docetaxel metabolite M2 in tumor tissue were reduced by ritonavir co-administration, whereas tumor RNA expression of Cyp3a was unaltered. In this breast cancer model, we observed no direct antitumor effect of ritonavir alone, but we found enhanced efficacy of docetaxel treatment when combined with ritonavir. Our data, therefore, suggest that decreased docetaxel metabolism inside the tumor as a result of Cyp3a inhibition contributes to increased antitumor activity.

Potential new chemotherapy strategy for human ovarian carcinoma with a novel KSP inhibitor

Among synthetic kinesin spindle protein (KSP) inhibitor compounds, KPYB10602, a six-member lactam-fused carbazole derivative was the most potent in vitro against cell growth of human ovarian cancer, A2780. KPYB10602 caused dose-dependent suppression of tumor growth in vivo. Mitotic arrest due to KPYB10602 was confirmed in vitro, and was characterized by inhibition of securin degradation. Apoptosis after mitotic arrest was associated with an increase in the ratio of pro-apoptotic Bax to anti-apoptotic Bcl-2. Increase of reactive oxygen species (ROS) and caspase pathway were also involved. Furthermore, KPYB10602 caused little neurotoxicity in vivo. Therefore, KPYB10602 could be a promising candidate as an anti-tumor agent with reduced adverse events for treating human ovarian cancer.

Chemotherapy and its evolving role in the management of advanced prostate cancer

Advanced prostate cancer has been recognized as being responsive to androgen deprivation since the 1940s when Charles Huggins first described the role of surgical castration in managing these patients. However, androgen deprivation only results in transient disease control for the vast majority of men, with those progressing in spite of castrate testosterone levels labeled as having castrate-resistant prostate cancer (CRPC). Until 2004, the therapeutic arena for these patients had remained stagnant, with no agent having shown a survival gain in the CRPC setting. Two landmark publications changed the prostate cancer treatment landscape by providing ‘level-1 evidence’ that docetaxel-based chemotherapy led to prolongation in overall survival (OS). This was followed by the approval of cabazitaxel in 2010 on the basis of Phase III data demonstrating its efficacy in patients pretreated with docetaxel. More recently, a number of next-generation androgen-directed agents (e.g. abiraterone and enzalutamide) have also been shown to lead to a survival benefit in men with CRPC. With so many new treatment options available, a number of questions remain. These include: how to best sequence chemotherapy with these newer hormonal agents, the clinical implication of cross-resistance between taxanes and androgen-directed agents and which subsets of patients may benefit most from early use of chemotherapy. This review will provide an overview of the evolving role of chemotherapy in the management of advanced prostate cancer in the current era.

Pretreatment with chemotherapeutics for enhanced nanoparticles accumulation in tumor: the potential role of G2 cycle retention effect

Ligands were anchored onto nanoparticles (NPs) to improve the cell internalization and tumor localization of chemotherapeutics. However, the clinical application was shadowed by the complex preparation procedure and the immunogenicity and poor selectivity and stability of ligands. In this study, a novel strategy was developed to elevate the tumor cellular uptake and tumor localization of NPs utilizing the G2/M phase retention effect of docetaxel, one of the most common chemotherapeutics. Results showed pretreatment with docetaxel could effectively arrest cells in G2/M phase, leading to an enhanced cell uptake of NPs, which may be caused by the facilitated endocytosis of NPs. In vivo imaging and slice distribution also demonstrated the pretreatment with docetaxel improved the localization of NPs in tumor. This strategy can be easily transferred to clinical for cancer management. Combination chemotherapeutics injections with commercial nano-drugs may result in better antitumor effect than the administration of a single drug.

The influence of prior abiraterone treatment on the clinical activity of docetaxel in men with metastatic castration-resistant prostate cancer

BACKGROUND

Taxanes may partly mediate their effect in castration-resistant prostate cancer (CRPC) through disruption of androgen-receptor trafficking along microtubules. This raises the possibility of cross-resistance between androgen-directed agents and docetaxel.

OBJECTIVE

To evaluate docetaxel efficacy after abiraterone treatment in CRPC patients.

DESIGN, SETTING, AND PARTICIPANTS

This was a single-institution, retrospective analysis in CRPC patients (N=119) who either received abiraterone before docetaxel (AD) (n=24) or did not receive abiraterone before docetaxel (docetaxel-only; n=95). Men initiated docetaxel between December 2007 (the date abiraterone was first used at our center) and May 2013.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary efficacy end points were prostate-specific antigen progression-free survival (PSA-PFS) and clinical/radiographic progression-free survival (PFS) on docetaxel. Differences between groups were assessed using univariate and multivariable analyses.

RESULTS AND LIMITATIONS

Men in the AD group had a significantly higher risk for progression than those in the docetaxel-only group. Median PSA-PFS was 4.1 mo in the AD group and 6.7 mo in the docetaxel-only group (p=0.002). Median PFS was also shorter in the AD group (4.4 mo vs 7.6 mo; p=0.003). In multivariable analysis, prior abiraterone treatment remained an independent predictor of shorter PSA-PFS (hazard ratio [HR]: 3.48; 95% confidence interval [CI], 1.36-8.94; p=0.01) and PFS (HR: 3.62; 95% CI, 1.41-9.27; p=0.008). PSA declines ≥50% were less frequent in the AD group (38% vs 63%; p=0.02). The small size and retrospective nature of this study may have introduced bias.

CONCLUSIONS

Men receiving abiraterone before docetaxel were more likely to progress on docetaxel and less likely to achieve a PSA response than abiraterone-naïve patients. Cross-resistance between abiraterone and docetaxel may explain these findings; however, larger, more definitive studies are still needed to confirm this.

PATIENT SUMMARY

We examined the efficacy of docetaxel in castration-resistant prostate cancer patients who either did or did not receive prior abiraterone. We found that men receiving abiraterone before docetaxel were less likely to achieve a PSA response and were more likely to progress sooner on docetaxel than abiraterone-untreated patients. This may be due to cross-resistance.

Natural product and natural product derived drugs in clinical trials

The 25 Natural Product (NP)-derived drugs launched since 2008 and the 100 NP-derived compounds and 33 Antibody Drug Conjugates (ADCs) in clinical trials or in registration at the end of 2013 are reviewed.

Dual silencing of Hsp27 and c-FLIP enhances doxazosin-induced apoptosis in PC-3 prostate cancer cells

We evaluated effect of dual gene silencing of Hsp27 and c-FLIP in doxazosin-induced apoptosis of PC-3 cell. After transfection using Hsp27 and c-FLIP siRNA mixture (dual silencing), doxazosin treatment was done at the concentrations of 1, 10, and 25 μM. We checked apoptosis of PC-3 cells with and TUNEL staining. We also checked interaction between Hsp27 and C-FLIP in the process of apoptosis inhibition. Spontaneous apoptotic index was 5% under single gene silencing of Hsp27 and c-FLIP and 7% under dual silencing of Hsp27 and c-FLIP. When doxazosin treatment was added, apoptotic indices increased in a dose-dependent manner (1, 10, and 25 μM): nonsilencing 10, 27, and 52%; Hsp27-silencing: 14, 35, and 68%; c-FLIP silencing: 21, 46, and 78%; dual silencing: 38, 76, and 92%. While c-FLIP gene expression decreased in Hsp27- silenced cells, Hsp27 gene expression showed markedly decreased pattern in the cells of c-FLIP silencing. The knockout of c-FLIP and Hsp27 genes together enhances apoptosis even under 1 μM, rather than low concentration, of doxazosin in PC-3 cells. This finding suggests a new strategy of multiple knockout of antiapoptotic and survival factors in the treatment of late-stage prostate cancer refractory to conventional therapy.