Antitumor Effect Of Docetaxel Research Articles

Antitumor Effects of Docetaxel in Truncated Basic Fibroblast Growth Factor- Functionalized Liposomes Delivered by d-α-tocopheryl Polyethylene Glycol 2000 Succinate.

PEGylation of stealth liposomes elevates their stability and prolongs plasma half-life. Stealth liposomes modified with targeting ligands are expected to be ideal drug delivery carriers. To encapsulate docetaxel in tbFGF (truncated basic fibroblast growth factor)-functionalized liposomes with mPEG2000-VE (d-κ-tocopheryl polyethylene glycol succinate, TPGS2K) and measure their antitumor effects in vitro and in vivo. TPGS2K and COOH-PEG2000-VE were synthesized, and tbFGF was conjugated to COOH-PEG2000-VE to prepare tbFGF-PEG2000-VE. Then, tbFGF-functionalized liposomes (DTX-tbFGF-LPs) were prepared by inserting tbFGF-PEG2000-VE into docetaxel liposomes comprising TPGS2K (DTX-PEG-LPs). The stabilities and drug release profiles of the formulation were evaluated. P-glycoprotein (P-gp) inhibition was measured by ATPase assay. MTT and cell uptake were measured with B16 cells. A B16 C57BL/6 mouse model was used to evaluate in vivo antitumor efficacy. Both DTX-PEG-LPs and DTX-tbFGF-LPs exhibited good stability and sustained drug release. MTT, flow cytometry, and fluorescence microscopy of B16 cells revealed higher antitumor activity and more efficient cell uptake for DTX-tbFGF-LPs compared with DTX-PEG-LPs and DTX-LPs. The P-gp ATPase assay showed that both PEG-LP and tbFGF-PEG-LP formulations inhibited P-gp pump activity in vitro. DTX-tbFGF-LPs had the highest antitumor efficacy and lowest toxicity in vivo. Truncated basic fibroblast growth factor-functionalized liposomes with TPGS2K as drug delivery nanocarriers were effective chemotherapy agents targeting FGFR-overexpressing tumors.

Combined treatment of apatinib with docetaxel in non-small-cell lung cancer mice and its material basis of pharmacokinetics.

e14069 Background: Apatinib, a small-molecule inhibitor of vascular endothelial growth factor receptor-2, has attracted many attentions due to its encouraging anticancer activity in clinic third-line treatment across a broad range of malignancies, including gastric cancer, non-small-cell lung cancer (NSCLC) and colorectal cancer. Its usage in second-line with chemotherapeutic drugs is still under exploration. This study is focus on the antitumor effect of apatinib combined with docetaxel (DTX) on NSCLC and its pharmacokinetic material basis. Methods: Apatinib (150 mg/kg, every day, p.o.) with or without DTX (8 mg/kg, q3d for four times, i.p.) was administered in A549 xenograft nude mice. The antitumor effect, histopathology of important organs and serum transaminases for liver function were detected. The metabolomic changes in serum were profiled by GC/MS and analyzed for the treatment outcome. The effect of apatinib on DTX concentrations in plasma, tumor and other tissues were determined by LC-MS/MS. The expressions of multidrug resistant transporters were detected. Effects of apatinib on the uptake, efflux and subcellular distribution of DTX in A549 cell and A549/DTX (DTX resistant) cell were investigated. Results: Apatinib enhanced the antitumor effect of DTX with alleviated DTX-induced inflammatory cells infiltration in liver and decreased serum transaminases (ALT and AST). Metabolomic results showed that serum endogenic molecules of apatinib and DTX co-treatment mice were closer to that of normal nude mice when compared to the DTX group. Apatinib significantly increased DTX concentration in tumor (up to 1.82 times) without enhancement in serum, heart, liver, lung and kidney. Additionally, apatinib decreased the DTX-induced upregulation of P-glycoprotein in tumor. In vitro, apatinib increased the cell/subcellular accumulation (especially in cytosol) and decreased the efflux of DTX in A549/DTX cells, while apatinib exerted no significant effect on cellular pharmacokinetics of DTX in A549 cells. Conclusions: Apatinib has a potential application prospect in second-line therapy combined with DTX for NSCLC patients, especially for multidrug resistant patients.

Improved Bioavailability and Antitumor Effect of Docetaxel by TPGS Modified Proniosomes: In Vitro and In Vivo Evaluations

A novel oral drug delivery system, TPGS modified docetaxel proniosomes (DTX-TPGS-PNs), was designed to enhance the oral bioavailability and antitumor efficiency of the poorly water-soluble drug docetaxel. DTX-TPGS-PN niosomes were 93 ± 6.5 nm in size, −18.53 ± 1.65 mV in zeta potential and exhibited spherical morphology, with an encapsulation efficiency of 97.31 ± 0.60%. The system showed sustained release in both simulated gastric and intestinal fluid. The results of caco-2 monolayer, everted gut sac model and improved single-pass intestinal perfusion model transport studies showed that DTX-TPGS-PN niosomes could significantly improve the absorption of DTX. The pharmacokinetics study suggested the absolute bioavailability of DTX-TPGS-PN niosomes were 7.3 times that of DTX solution. In addition, a higher antitumor efficacy than DTX solution was demonstrated in MCF-7 and MDA-MB-231 cells in vitro and in MCF-7 tumor-bearing mice model in vivo. Our results demonstrated DTX-TPGS-PN is promising in enhancing the bioavailability and efficiency of poorly water-soluble drug DTX, and the potential of proniosomes as stable precursors for oral drug delivery.

Abstract 4813: Magnetic iron oxide nanoparticles enhance anti-tumor effect of docetaxel on prostate cancer cells via ROS generation and NF-kappa B signaling

Abstract Chemotherapy is one of treatment options for castration-resistant prostate cancer. Especially, docetaxel-based chemotherapy has been shown to improve the quality of life in patients with the advanced disease. However, this needs to be improved because of limitations by lack of specificity, toxicity, and progression of docetaxel-resistance. Thus, combination of docetaxel with other compounds or drugs is needed to overcome these problems. Magnetic iron oxide nanoparticles (MgNPs, Fe3O4) have been investigated for nanomedicine such as drug delivery, cancer diagnosis and therapy. We have also shown that MgNPs would modify the effect of chemotherapy in prostate cancer cells in vitro. The purpose of this study was to analyze the combined effect of docetaxel and non-/carboxyl-modified magnetic nanoparticles (MgNPs/MgNPs-COOH) on a prostate cancer cell line, DU145 and clarify their mechanisms. While only MgNPs produced reactive oxygen species (ROS) and 8-OHdG, MgNPs-COOH did neither produce ROS nor 8-OHdG. The combination of docetaxel and MgNPs-COOH more effectively inhibited cancer cell growth and induced apoptosis compared with combination of docetaxel and MgNPs. Although docetaxel induced NF-kappa B expression, combination of docetaxel and MgNPs inhibited NF-kappa B expression compared with combination of MgNPs-COOH and docetaxel. However, both combinations increased p-Akt expression. These results suggest that MgNPs/MgNPs-COOH may enhance effect of docetaxel on prostate cancer cells via NF-kappa B signaling, however different factors may be involved in these phenomena, leading to new tumor ablation therapies. Citation Format: Kanako Kojima, Saho Hashimoto, Rina Sakamaki, Sanai Takahashi, Risa Kasakura, Ryo Maruyama, Tadashi Nittami, Hitoshi Ishiguro, Hiroji Uemura, Masatoshi Watanabe. Magnetic iron oxide nanoparticles enhance anti-tumor effect of docetaxel on prostate cancer cells via ROS generation and NF-kappa B signaling. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4813.

Abstract 4745: Repurposing of valproic acid and simvastatin combination as anticancer agents in prostate cancer: synergistic interaction with docetaxel and suppression of docetaxel resistance

Abstract Although docetaxel (DTX) remains a standard of care for advanced prostate cancer (PCa), limited long-term responses, side effects and resistant disease suggested the need of novel combination strategies. Increased expression of histone deacetylases (HDAC) and alteration of the mevalonate pathway (MVP) are common aberrations in PCa. In this study, we analyzed the antitumor effect of DTX in combination with valproic acid (VPA), an anticonvulsant with HDAC inhibitory activity, and simvastatin (SIM), a cholesterol-lowering drug inhibiting the rate-limiting enzyme of MVP HMG-CoA reductase, on androgen-dependent 22RV1 and LNCAP and androgen-independent PC3 and DU145 PCa cells, as well as on the highly aggressive SIM-resistant DU145R80 subline developed in our laboratory from DU145 cells (Milone MR et al. Cell Death Dis. 2013; Milone MR et al. Oncotarget 2014). We first showed a potent synergistic anti-proliferative effect of VPA/SIM combination, assessed by calculating combination index (CI) according to the method of Chou and Talalay, on all cell lines, including SIM-resistant cells, whatever schedule of administration (simultaneous vs sequential) we used, confirming our previous data on the combination between the HDAC inhibitor (HDACi) panobinostat and zoledronic acid, the latter also targeting the MVP pathway (Bruzzese F. et al, Cell Death Dis. 2013). Notably, exposure to triple combinations (VPA/SIM/DTX) resulted in a further strong synergistic anti-proliferative effect, with sequential exposure with 24h delay between VPA/SIM and DTX as the best schedule. The synergistic interaction of VPA/SIM and DTX combination involved apoptotic effect, measured by FACS analysis of sub-diploid DNA content and caspase 3/7 cleavage, and DNA damage induction, assessed by γH2AX expression. Synergistic effect of VPA/SIM and DTX combination was confirmed by soft agar clonogenic assay and by 3D culture on self-assembled PCa spheroids. Significantly, VPA/SIM combination was also able to revert DTX-resistance in DTX-resistant PC3 and DU145 sublines developed in our laboratory from the parental cells. All together these findings suggested that the combination of two safe generic drugs such as VPA and SIM can improve DTX efficacy, representing a novel therapeutic approach that warrant clinical investigation in advanced PCa patients. Our study also suggests a new strategy to overcome resistance to standard taxane-based therapy in PCa patients. Citation Format: Federica Iannelli, Rita Lombardi, Biagio Pucci, Maria Rita Milone, Chiara Ciardiello, Alessandra Leone, Elena Di Gennaro, Alfredo Budillon, Francesca Bruzzese. Repurposing of valproic acid and simvastatin combination as anticancer agents in prostate cancer: synergistic interaction with docetaxel and suppression of docetaxel resistance. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4745.

Docetaxel induces Bcl-2- and pro-apoptotic caspase-independent death of human prostate cancer DU145 cells.

Docetaxel is a useful chemotherapeutic agent for the first-line treatment of hormone-refractory prostate cancer. Abnormal expression of Bcl-2 is commonly found in cancer cells, which increases their anti-apoptotic potency and chemo-resistance. We investigated the effects of Bcl-2 expression status on the susceptibility of DU145 cells, an androgen-independent human prostate cancer cell line, to docetaxel and other anticancer agents. A panel of Bcl-2-expressing DU145 cell lines was established. Bcl-2 expression levels were unrelated to the susceptibility of DU145 cells to docetaxel. The sensitivity of DU145 cells to cisplatin fluctuated, and the sensitivity to tumor necrosis factor (TNF)-α was decreased by Bcl-2 overexpression. In a xenograft mouse model, overexpression of Bcl-2 drastically decreased the sensitivity of DU145 cells to cisplatin and TNF-α; however, there was no change in the response to docetaxel. Fluorescent microscopy revealed that Bcl-2-overexpression had no effect on the docetaxel-induced death of DU145 cells, but significantly decreased DU145 cell death induced by cisplatin or TNF-α. Interestingly, docetaxel hardly induced caspase-3/7 activation in control or Bcl-2-overexpressing DU145 cells, but did at a low level in LNCaP cells, another prostate cancer cell line. Moreover, in contrast to LNCaP cells, the reduced viabilities of docetaxel-treated control and Bcl-2-overexpressing DU145 cells were not restored by the addition of either a Bid inhibitor or a panel of pro-apoptotic caspase inhibitors. These findings indicate that the antitumor effects of docetaxel on DU145 cells are independent of both Bcl-2 and pro-apoptotic caspases.

Abstract B12: Endothelial stabilizer SAC-1004 normalizes tumor vasculature and potentiates docetaxel chemotherapy in prostate cancer

Abstract Background: Since tumor requires excessive oxygen and nutrients due to their rapid growth, tumor is generally vascular. However, tumor vasculature is not physiologic but leaky, dilated, and tortuous. The inefficiency of tumor vessels in terms of perfusion induces hypoxic stress that makes the tumor more aggressive. Here, we investigated the role of a novel endothelial stabilizer SAC-1004 on tumor vascular normalization and its effects on tumor growth in prostate cancer. Methods: Human vascular endothelial cell (HUVEC) was used to evaluate the effects of SAC-1004 on endothelial cells. Immunocytochemical staining and immunofluorescent confocal imaging was performed for E-cadherin expression in HUVECs. MTS assay was performed to assess cell proliferation of HUVECs and PC-3 cells after SAC-1004 treatment. Immunohistochemical staining with anti-CD31 and anti-SMA antibodies was performed to assess vasculature in vivo. PC-3 subcutaneous xenografts were developed to evaluate the effects of SAC-1004 on tumor vasculature and tumor growth in prostate cancer. Magnetic resonance images were taken to assess vascular perfusion in xenografts. SAC-1004 was administrated via tail vein once a day for 7 days. Docetaxel was administrated intravenously once a week. Results: SAC-1004 restored junction protein E-cadherin in vitro in endothelial cells and significantly reduced VEGF-induced retinal vascular leakage. SAC-1004 promoted proliferation of HUVECs in vitro in a dose-dependent manner. However, proliferation of cancer cells was not significantly affected by SAC-1004 treatment. Reduced vascular leakiness was found in PC-3 xenografts treated with SAC-1004 treatment and magnetic resonance imaging after SAC-1004 treatment for 7 days confirmed improved perfusion in the PC-3 xenografts treated with SAC-1004 compared with control. Interestingly, SAC-1004 treatment suppressed tumor growth in PC-3 xenografts but SAC-1004 followed by intravenous docetaxel treatment showed the most potent tumor suppression compared with control in PC-3 xenografts. Conclusions: SAC-1004 restored abnormal leak vasculature of tumor by restoring endothelial cell junction in prostate cancer. Vascular normalization by SAC-1004 induced tumor regression and combination with docetaxel following vascular normalization potentiated anti-tumor effects of docetaxel in prostate cancer. Citation Format: Yoo Hyun Kang, Jun Hyeok Heo, Hyun A Jin, Ki Chung Park, Sung Joon Hong, Kyung Seok Han. Endothelial stabilizer SAC-1004 normalizes tumor vasculature and potentiates docetaxel chemotherapy in prostate cancer. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Angiogenesis and Vascular Normalization: Bench to Bedside to Biomarkers; Mar 5-8, 2015; Orlando, FL. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl):Abstract nr B12.

Antitumor Effect of Docetaxel in Osteosarcoma by the Inhibition of Wnt Signal Channel.

Osteosarcoma (OS) is the most common type of malignant bone tumor in adults and children. Despite the great strides in biology and medicine, the survival rate of patients with metastatic disease remains very poor. This rate has been staggering with recurrence and metastasis. In the present study, we proposed Wnt/β-catenin pathway as a key biological target for the effective treatment in OS. Wnt signaling has been reported to play important roles in osteoblastogenesis. We hypothesized that docetaxel (DTX) will effectively arrest the osteosarcoma progression by suppressing the Wnt/β-catenin pathway in OS cells. Our results show that DTX significantly inhibited the cell proliferation of U2OS and SaOS-2 cancer cells in a time-dependent and dose-dependent manner. DTX inhibited the intrinsic transcriptional activity of β-catenin/Tcf in U2OS cancer cells and SaOS-2 cancer cells. GSK-3βinhibitor (SB216763) treatment remarkably increased the β-catenin/Tcf transcriptional activities. The transcriptional activities have been increased by around ~200% due to the decrease in the degradation of β-catenin mediated through GSK-3β. Summarizing, present study clearly showed that DTX inhibited Wnt/β-catenin signalling pathways and significantly reduced the matrix metallopeptodase 9 (MMP-9) protein expressions and its activity. Taken together, our findings provide novel insight on the effect of anticancer small molecules to improve the outcomes in osteosarcoma.

The Antitumor Effect of a New Docetaxel-Loaded Microbubble Combined with Low-Frequency Ultrasound In Vitro: Preparation and Parameter Analysis

To develop a novel docetaxel (DOC)-loaded lipid microbubbles (MBs) for achieving target therapy and overcoming the poor water-solubility drawback of DOC. A novel DOC-loaded microbubble (DOC + MB) was prepared by lyophilization and the physicochemical properties including ultrasound contrast imaging of the liver were measured. The anti-tumor effect of the DOC + MBs combined with low-frequency ultrasound (LFUS; 0.8 Hz, 2.56 W/cm², 50% cycle duty) on the DLD-1 cancer cell line was examined using an MTT assay. The physicochemical properties of the two tested formats of DOC + MBs (1.0 mg and 1.6 mg) was shown: concentration, (6.74 ± 0.02) × 10⁸ bubbles/mL and (8.27 ± 0.15) × 10⁸ bubbles/mL; mean size, 3.296 ± 0.004 μm and 3.387 ± 0.005 μm; pH value, 6.67 ± 0.11 and 6.56 ± 0.05; release rate, 3.41% and 12.50%; Zeta potential, -37.95 ± 7.84 mV and -44.35 ± 8.70 mV; and encapsulation efficiency, 54.9 ± 6.21% and 46.3 ± 5.69%, respectively. Compared with SonoVue, the DOC + MBs similarly enhanced the echo signal of the liver imaging. The anti-tumor effect of the DOC + MBs/LFUS group was significantly better than that of DOC alone and that of the normal MBs/LFUS groups. The self-made DOC + MBs have potential as a new ultrasound contrast agent and drug-loaded microbubble, and can obviously enhance the antitumor effect of DOC under LFUS exposure.

Antisense oligodeoxynucleotide targeting HER2 mRNA sensitized docetaxel in breast cancer treatment

Context: Human epidermal growth factor receptor 2 (HER2) is one of the oncogenes closely associated with the development and prognosis of breast carcinoma. Down-regulation of HER2 mRNA by antisense oligodeoxynucleotide (ASO) HER2 has been suggested to be a feasible treatment for patients with breast carcinoma.Objective: The antitumor effects of ASO HA6722 were investigated in vitro and in vivo.Materials and methods: In this study, SK-BR-3, a HER2-overexpressing breast carcinoma cell line, was used as the model for in vitro experiments. Inhibitory effects of the ASO HA6722 were detected by methyl-thiazoldiphenyl tetrazolium (MTT) assay. Meanwhile, HER2 mRNA levels were monitored by reverse transcription polymerase chain reaction (RT-PCR). The in vivo antitumor effects were evaluated in nude mice xenograft model.Results: Our results showed that HA6722 alone could inhibit the growth of SK-BR-3 cells in a dose-dependent manner with the IC50 value of 41.8 ± 8.1 nM. In addition, the antitumor effect of docetaxel (TXT) could be sensitized by low dose of HA6722 both in vitro and in vivo, suggesting that ASO HA6722 could inhibit the growth of breast cancer cells and enhance the cytotoxic effects of TXT.Discussion and conclusion: The combination treatment of TXT and HA6722 could be a more effective approach for breast cancer treatment. The future study should focus on the antitumor effect in other models.

Abstract 179: Histone deacetylase inhibitor; CG005, is a novel anticancer drug; as a combination drug with docetaxel in prostate cancer

Abstract We synthesized a novel hydroxamate-based HDACi, CG0005 {(E)-2-(Naphthalen-1-yloxymethyl)-oct-2-enedioic acid 1-[(3-dimethylamino-propyl)-amide] 8-hydroxyamide]}. Like other inhibitors, for example SAHA and PXD 101, CG0005 has the hydroxamic acid moiety to bind zinc at the bottom of catalytic pocket. The aliphatic chain of CG0005, which is presumed to be positioned at the narrow channel of pocket, is less flexible than that of SAHA and less rigid than that of PXD101. Of the other moieties, the tertiary amine was adopted to improve water solubility. Firstly, we analyzed its activity in hormone-dependent LNCaP cells and hormone-refractory DU145 and PC3 cells. CG0005 inhibited deacetylation of histone3 and tubulin as much as vorinostat and belinostat. CG0005 also inhibited growth of prostate cancer cells and increased sub-G1 population and activated caspase-9, -3 and -8. These results indicated that CG0005 induced apoptosis in prostate cancer cell lines. Next, we examined the effect of CG0005 on cell death induced by docetaxel in DU145 cells in vitro and in vivo. Pre-treatment of DU145 cells with docetaxel followed by CG0005 showed synergistic cytotoxicity, and increased the apoptotic sub-G1 population, caspase activation, and tubulin acetylation, compared with docetaxel alone. Moreover, the combination treatment decreased Mcl-1, Bcl-xl and cyclin D1. Docetaxel and CG0005 combination reduced tumor size in the DU145 xenograft model. These preclinical results show that post-treatment with CG0005 potentiated anti-tumor effect of docetaxel in hormone-refractory prostate cancer (HRPC) cells via intrinsic and extrinsic apoptotic pathway in vitro and in vivo. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 179. doi:10.1158/1538-7445.AM2011-179

Abstract 1793: Platelet-derived growth factor receptor alpha blockade significantly enhances sensitization to docetaxel in ovarian carcinoma

Abstract Objective: Platelet-derived growth factor receptor alpha (PDGFRα) is a member of class III receptor tyrosine kinase and is associated with cell survival. Here, we examined whether PDGFRα blockade enhances the anti-tumor activity of taxanes in ovarian carcinoma. Methods: PDGFRα expression was evaluated with RT-PCR and Western blot in multiple ovarian cancer cell lines. Human-specific monoclonal antibody to PDGFRα (IMC-3G3, ImClone Systems, NJ, USA) was used for in-vitro (cell viability assay, apoptosis assay) and in-vivo experiments with or without docetaxel. Results: All eleven tested ovarian cancer cell lines had variable expression of PDGFRα. OVCA433 cell line had the highest level of expression of PDGFRα. IMC-3G3 blocked PDGFRα phosphorylation in response to PDGF-AA stimulation. IMC-3G3 alone had no affect on cell viability in all tested cell lines. However, IMC-3G3 significantly enhanced sensitization to docetaxel: IC50 reduction rate, SKOV3-ip1, 25.5%; HeyA8-parental, 31.7%; OVCA433, 35.3%; and HeyA8-MDR, 44.2% (all, p<0.05). While treatment with IMC-3G3 alone did not increase apoptosis, concurrent use with docetaxel significantly enhanced docetaxel-mediated apoptosis (mean percentage of total apoptotic cells in SKOV3-ip1, untreated vs IMC-3G3 alone vs docetaxel alone vs docetaxel with IMC-3G3, 7.3% vs 7.1% vs 15.4% vs 22.2%, p<0.001). In the in-vivo experiment with SKOV3-ip1 bearing mice, administration of IMC-3G3 monotherapy had no significant anti-tumor effects compared to the control group (mean tumor weight, 2.5 ± 0.32 vs 2.9 ± 0.51 grams, p>0.05). Concurrent use of IMC-3G3 with docetaxel significantly reduced tumor weight compared to docetaxel alone (mean tumor weight, 0.22 ± 0.07 vs 0.63 ± 0.14 grams, tumor reduction rate 65.1%, p<0.05). Conclusion: IMC-3G3 significantly enhances the anti-tumor effects of docetaxel. Therefore, targeting PDGFRα may be an attractive approach for increasing the cytotoxic effects of chemotherapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1793.

Time-dependent gene expression changes in a xenograft model of docetaxel cytotoxicity.

Abstract Abstract #2009 Background: The antitumor effects of docetaxel primarily result from mitotic arrest with impaired cell proliferation. However, the key molecular pathways affected by this agent are largely unknown, and alternative mechanisms of action are likely. Knowledge of these pathways and mechanisms will guide the rational design of more effective treatment schedules and drug combinations. We hypothesize that the molecular analysis of treated human breast cancer xenografts will allow for an evaluation of time-dependent alterations in the expression of genes involved in key cell processes related to docetaxel cytotoxicity.
 Methods: Gene expression profiles were generated from MDA-MB-231 breast cancer xenografts after a single intravenous dose of docetaxel. Tumors were harvested at 1, 6, 12, and 24 hours (hr) after drug administration; a control group of untreated tumors (0hr) was included. RNA was extracted, assessed for concentration and quality, and used to generate probes for hybridization to the Affymetrix Human U133A oligonucleotide gene chip. Gene expression levels were explored with MAS 5.0 software and in-house algorithms. Subsequent data analysis included cross-experiment normalization, differential gene selection, gene clustering, and peak-time latency analysis. Consistency between the in-house in vivo dataset and a public in vitro dataset (Oncogene. 26:2902) was investigated.
 Results: 5087 responsive genes were selected using both SAM and EDGE. Among these genes, 3009 were down-regulated and 190 were up-regulated by at least 2-fold. Compared with 0h, the most significant changes in gene expression took place 6h after drug administration (2023 down-regulated and 655 up-regulated genes). Gene clustering revealed the sequence of up-regulation or down-regulation of different gene groups. Apoptosis-related genes and cell cycle-related genes in various stages showed different time latency patterns. For example, most of the M phase genes (total of 65 from Gene Ontology) were down-regulated 6h and 12h after docetaxel treatment and recovered by 24h. In addition, 1489 of 3009 down-regulated genes and 55 of 190 up-regulated genes were found in a public in vitro dataset; these datasets share 282 down-regulated genes (18.9%) and 17 up-regulated genes (30.9%).
 Discussion: Analysis of serial gene expression changes in docetaxel sensitive breast cancer xenografts demonstrates that time-dependent changes in specific cell processes occur. These findings will be expanded to distinguish between early and late molecular mechanisms of docetaxel responsiveness. A parallel xenograft model of docetaxel nonresponsiveness is also under investigation. In this way, time-dependent pathways will be defined that will include predictive biomarkers and lead to the development of novel agents to overcome resistance or enhance sensitivity to docetaxel, one of the most effective agents available for the treatment of breast cancer. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2009.

Histamine enhanced antitumor effect of docetaxel and dacarbazine in human clear cell sarcoma xenografts in nude mice

Histamine enhanced antitumor effect of docetaxel and dacarbazine in human clear cell sarcoma xenografts in nude mice

272 poster Experimental study of the antitumor effects of docetaxel on irradiation in vivo

272 poster Experimental study of the antitumor effects of docetaxel on irradiation in vivo

Lack of correlation between mitotic arrest or apoptosis and antitumor effect of docetaxel.

To determine, as we did for paclit-axel, whether mitotic arrest and apoptosis induced in murine tumors in vivo by docetaxel correlate with the drug's antitumor effect and whether the antitumor efficacy of docetaxel depends on p53 mutational status of tumors. C3Hf/Kam mice were implanted with one of the following 15 syngeneic tumors: seven adenocarcinomas (MCa-4, MCa-29, MCa-35, MCa-K, OCa-I, ACa-SG, and HCa-I), two squamous cell carcinomas (SCC-IV and SCC-VII), five sarcomas (FSa, FSa-II, Sa-NH, NFSa, and Sa-4020) and one lymphoma (Ly-TH). When the tumors had grown to 8 mm in diameter, the mice were treated with 31.3 mg/kg docetaxel i.v. Tumor growth delay was the endpoint of docetaxel's antitumor effect. In separate groups of mice, mitotic arrest and apoptosis were determined micromorphometrically 1 to 72 h after docetaxel treatment. Tumors were assayed for their p53 status by sequence analysis of RNA prepared from freshly excised tumors. Docetaxel caused statistically significant growth delay in six of seven adenocarcinomas, three of five sarcomas, and the lymphoma, but not in either of the squamous cell carcinomas. The drug induced mitotic arrest in all tumor types, but to various degrees ranging from 6.4+/-0.4% to 25.1+/-0.1%. In contrast, docetaxel induced appreciable apoptosis in only 5 of 15 tumors, with 10.3+/-1.6% being the highest apoptotic value. Neither mitotic arrest nor apoptosis were significantly correlated with tumor growth delay. However, tumors that responded to docetaxel by significant tumor growth delay histologically displayed massive cell destruction by cell lysis, and four of these tumors also showed marked infiltration with mononuclear lymphoid cells. Of the 15 tumors only 3 had mutant p53. Docetaxel exhibited a strong antitumor effect in two-thirds of murine tumors, and on a milligram per kilogram basis was more effective than paclitaxel against the same tumors. The drug was a potent inducer of mitotic arrest but a weak inducer of apoptosis, neither of which correlated with its antitumor effect. Tumor cell lysis appeared to be a major mode of tumor cell destruction and can be regarded as the main mechanism underlying antitumor efficacy of docetaxel. In contrast, paclitaxel's antitumor efficacy is related to its ability to induce apoptosis. At the molecular level, there was no dependency of antitumor efficacy of docetaxel on p53 mutational status of tumors.