Presence Of Paclitaxel Research Articles

The Impact of Paclitaxel-Containing Nanoliposomes on the Proliferation of and Invasion by Ovarian Cancer Cells

Our goal was to explore the impact of paclitaxel-containing nanoliposomes (PTXN) on the proliferation of and invasion by ovarian carcinoma cells. An MTT assay was used to examine growth of SKOV3 and HO8910 ovarian carcinoma cells in the presence of paclitaxel (TAX) alone or PTXN. Transwell invasion assays were performed; Western blot and qRT-PCR were used to examine expression of matrix metallopeptidase (MMP)-9. PTXN administered at concentrations from 0.625–10 μg/mL was more effective at inhibiting the proliferation of SKOV3 and HO8910 cells than was TAX alone (P < 0.05). Administration of PTXN to these cells reduced their capacity for invasion, and expression of MMP-9 mRNA and protein over that achieved by administration of TAX alone (P < 0.05). PTXN promotes more effective inhibition of invasion of ovarian carcinoma cells than does TAX alone.

The Effects of Paclitaxel in the Combination of Diamond Nanoparticles on the Structure of Human Serum Albumin (HSA) and Their Antiproliferative Role on MDA-MB-231cells.

Since the interactions of anti-cancer agents with blood constituents, in particular with human serum albumin (HSA) may have a major impact on drug pharmacology, the present study designed to provide a fundamental understanding of the interaction of nanodiamonds (NDs) together with paclitaxel (PTX) with HSA in detail for the first time. The UV-Vis, steady-state fluorescence, far-UV CD and zeta potential results displayed that PTX + NDs could form a complex with HSA. Additionally, the values of binding constants and ΔG° showed that PTX + NDs interact strongly with HSA compared to PTX or NDs alone and the hydrophobic force plays a major role in this interaction. Moreover, the in vitro release behavior of PTX + NDs form HSA can be regulated at dissimilar pH levels. The anticancer property of 0.5µM PTX + 20µM NDs by MTT assay demonstrates that this combination can tremendously diminish the proliferation of MDA-MB-231cells compared to PTX or NDs alone. Altogether, the structure of HSA changed moderately in the presence of PTX + NDs and PTX + NDs can promote mortality of MDA-MB-231 cells besides those mortality effects induced via PTX or NDs alone. The results obtained from this study can help in understanding the pharmacokinetic properties of PTX + NDs.

177Lu-Bombesin-PLGA (paclitaxel): A targeted controlled-release nanomedicine for bimodal therapy of breast cancer.

The gastrin-releasing peptide receptor (GRPr) is overexpressed in >75% of breast cancers. 177Lu-Bombesin (177Lu-BN) has demonstrated the ability to target GRPr and facilitate efficient delivery of therapeutic radiation doses to malignant cells. Poly(d,l‑lactide‑co‑glycolide) acid (PLGA) nanoparticles can work as smart drug controlled-release systems activated through pH changes. Considering that paclitaxel (PTX) is a first-line drug for cancer treatment, this work aimed to synthesize and chemically characterize a novel polymeric PTX-loaded nanosystem with grafted 177Lu-BN and to evaluate its performance as a targeted controlled-release nanomedicine for concomitant radiotherapy and chemotherapy of breast cancer. PLGA(PTX) nanoparticles were synthesized using the single emulsification-solvent evaporation method with PVA as a stabilizer in the presence of PTX. Thereafter, the activation of PLGA carboxylic groups for BN attachment through the Lys1-amine group was performed. Results of the chemical characterization by FT-IR, DLS, HPLC and SEM/TEM demonstrated the successful synthesis of BN-PLGA(PTX) with a hydrodynamic diameter of 163.54 ± 33.25 nm. The entrapment efficiency of paclitaxel was 92.8 ± 3.6%. The nanosystem showed an adequate controlled release of the anticancer drug, which increased significantly due to the pH change from neutral (pH = 7.4) to acidic conditions (pH = 5.3). After labeling with 177Lu and purification by ultrafiltration, 177Lu-BN-PLGA(PTX) was obtained with a radiochemical purity of 99 ± 1%. In vitro and in vivo studies using MDA-MB-231 breast cancer cells (GRPr-positive) demonstrated a 177Lu-BN-PLGA(PTX) specific uptake and a significantly higher cytotoxic effect for the radiolabeled nanosystem than the unlabeled BN-PLGA(PTX) nanoparticles. Using a pulmonary micrometastasis MDA-MB-231 model, the added value of 177Lu-BN-PLGA(PTX) for tumor imaging was confirmed. The 177Lu-BN-PLGA(PTX) nanomedicine is suitable as a targeted paclitaxel delivery system with concomitant radiotherapeutic effect for the treatment of GRPr-positive breast cancer.

Reorganization of paclitaxel-stabilized microtubule arrays at mitotic entry: roles of depolymerizing kinesins and severing proteins

ABSTRACTPaclitaxel is a widely used anti-cancer treatment that disrupts cell cycle progression by blocking cells in mitosis. The block at mitosis, with spindles assembled from short microtubules, is surprising given paclitaxel’s microtubule stabilizing activity and the need to depolymerize long interphase microtubules prior to spindle formation. Cells must antagonize paclitaxel’s microtubule stabilizing activity during a brief window of time at the transition from interphase to mitosis, allowing microtubule reorganization into a mitotic spindle, although the mechanism underlying microtubule depolymerization in the presence of paclitaxel has not been examined. Here we test the hypothesis that microtubule severing and/or depolymerizing proteins active at mitotic entry are necessary to clear the interphase array in paclitaxel-treated cells and allow subsequent formation of mitotic spindles formed of short microtubules. A549 and LLC-PK1 cells treated with 30nM paclitaxel approximately 4 h prior to mitotic entry successfully progress through the G2/M transition by clearing the interphase microtubule array from the cell interior outward to the cell periphery, a spatial pattern of reorganization that differs from that of cells possessing dynamic microtubules. Depletion of kinesin-8s, KIF18A and/or KIF18B obstructed interphase microtubule clearing at mitotic entry in paclitaxel-treated cells, with KIF18B making the larger contribution. Of the severing proteins, depletion of spastin, but not katanin, reduced microtubule loss as cells entered mitosis in the presence of paclitaxel. These results support a model in which KIF18A, KIF18B, and spastin promote interphase microtubule array disassembly at mitotic entry and can overcome paclitaxel-induced microtubule stability specifically at the G2/M transition.

Structural effects of Diamond nanoparticles and Paclitaxel combination on calf thymus DNA

The combination effects of nanodiamonds (NDs) and Paclitaxel (PTX) on the DNA structure were examined. The UV-Visible, steady-state and time-resolved fluorescence spectroscopy, CD, viscosity and zeta potential results showed that PTX + NDs could form a complex via groove binding mechanism. The values of binding constants, ΔG° and ΔH° and ΔS° values showed that PTX + NDs interact strongly with DNA and the hydrophobic force plays main role in this interaction. The and Tm study indicated the instability of DNA in presence of PTX + NDs. This study demonstrated that NDs could enhance the effect of PTX on DNA structure as well as its affinity and binding to DNA.

Resveratrol enhances chemosensitivity of renal cell carcinoma to paclitaxel.

By restraining proliferation and promoting apoptosis, resveratrol (RES) has anti-tumor effect in various cancers. Here, we examine whether RES exerts similar effect in drug-resistant renal cell carcinoma (RCC). To this end, Caki-1 cells derived from renal carcinoma are subjected to escalated doses of paclitaxel (PTX) to produce the PTX resistant Caki-1PTX cells. Both Caki-1 and Caki-PTX cells are sensitive to PTX, in a dose dependent manner. RES, dose-dependently, suppresses the expression of survivin, a molecular biomarker of cancer and a member of the inhibitor of apoptosis (IAP) family and its co-administration with PTX inhibits the effect of this drug on cell viability. To decipher whether survivin expressed by cancer cells is involved in rendering cells PTX sensitive, survivin is overexpressed. This dramatically counteracts the effects of RES on cell survival in the presence of PTX. Furthermore, decrease of survivin by inhibition of PI3K/AKT pathway significantly inhibits the effect of PTX in Caki-1PTX cells. These data show that RES increases the sensitivity of PTX resistant renal cells to drug treatment.

The nanoparticle-facilitated autophagy inhibition of cancer stem cells for improved chemotherapeutic effects on glioblastomas.

Due to the rapid growth of a tumor, the tumor cell metabolism becomes more active, resulting in the overexpression of albumin-binding proteins for transporting albumin as an energy and amino source. In that case, making use of nutrient transporters for targeted drug delivery to the brain becomes attractive. Herein, we synthesized albumin nanoparticles by a desolvation process, modified them with folic acid to enhance blood-brain-barrier (BBB) penetration and cellular uptake, and then loaded them with the antitumor drug paclitaxel (PTX) and autophagy inhibitor chloroquine (CQ) for combination therapy. The albumin nanoparticles could cross the BBB and target glioma cells effectively, and the combination therapy of PTX and CQ induced more cell apoptosis than PTX treatment alone in vitro. The results of the role of autophagy in the sensitivity of chemotherapeutic PTX to glioma cells showed that the stemness-associating genes (SOX2, POU5F1 and NANOG) of live glioma cells increased in the presence of PTX, while they dropped sharply with the combination including CQ. More importantly, it was found that the combined delivery system FA-BSA-NPPTX/CQ exhibited the most effective cell apoptosis. Our findings demonstrated that drug-loaded albumin nanoparticles could facilitate a combination of chemotherapy and autophagy inhibition for effective glioma therapy.

Bio-inspired construction of cellulose-based molecular imprinting membrane with selective recognition surface for paclitaxel separation

Separating the natural product of paclitaxel from its structural analogs still remains a significant challenge. In this work, a novel molecular imprinting membrane (Cell/SiO2-MIM) with specific recognition sites was hierarchically constructed for paclitaxel (PTX) separation. Inspired by mussel, inorganic silica nanoparticles (SiO2 NPs) were introduced onto the surface of the regenerated cellulose membrane as polymerization platform in an attempt to enhance the permeation flux of the membrane. The specific recognition sites of PTX were constructed on the nanoscale silica surface through the bulk polymerization of vinylpyridine in the presence of PTX as templates, leading to the membrane with the selective recognition ability for the target molecule (PTX). The as-synthesized imprinting membrane exhibited excellent selective adsorption capacity and perm-selectivity towards PTX, with the maximum adsorption amount and separation factor of 46.36 mg/g and 3.77, respectively. Moreover, after six consecutive adsorption and desorption cycles, the membrane maintained the excellent stability and reusability, which facilities its potential application in an industrial scale.

Surfactant-Stripped Micelles of Near Infrared Dye and Paclitaxel for Photoacoustic Imaging Guided Photothermal-Chemotherapy.

Development of nanoagents with strong near-infrared (NIR) absorbance and high photothermal conversion capacity is highly desired for efficient photoacoustic (PA) imaging and photothermal therapy of cancers. Herein, surfactant-stripped micelles with photostable near-infrared dye, β-thiophene-fused BF2 -azadipyrromethene (aza-BDTP), are prepared in the presence of paclitaxel (PTX) with Pluronic F127 as the surfactant. Distinct from hydrophobic aza-BDTP and PTX, the obtained surfactant-stripped micelles aza-BDTP/PTX show excellent solubility, physiological stability, and high loading efficiencies for corresponding aza-BDTP and PTX. Intriguingly, these aza-BDTP/PTX micelles exhibit high photothermal conversion efficiency at 33.9%, significantly higher than 16.9% for bare aza-BDTP molecules, owing to aggregation-induced quenching of aza-BDTP fluorescence. With excellent photostability, aza-BDTP/PTX micelles appear to be a highly stable photoacoustic imaging probe and show efficient tumor accumulation as visualized under photoacoustic imaging upon intravenous injection. After being irradiated with a 785 nm laser, 4T1 tumors on the mice with systemic administration of aza-BDTP/PTX micelles are fully eradiated without any recurrences within 60 d. This work presents a general method for efficient encapsulation of hydrophobic aza-BDTP and PTX, obtaining hybrid aza-BDTP/PTX micelles as promising nanotheranostics for imaging guided cancer combination therapy.

Pure paclitaxel nanoparticles: preparation, characterization, and antitumor effect for human liver cancer SMMC-7721 cells.

IntroductionPure paclitaxel nanoparticles (PPN), consisting entirely of drug molecules, were prepared by the electrostatic spraying method as promising candidates for antitumor application. Compared with the traditional preparation method, the advantage of the electrostatic spraying method included high production rates, relatively small particle sizes, and ease of preparation.Materials and methodsPaclitaxel was used to prepared PPN by electrostatic spray. The electrostatic spray device included a constant speed pump with a syringe, a high-voltage power supply, and a metal foil receiver was used to prepare and evaluate PPN. The syringe drew off a certain amount of paclitaxel chloroform solution (150 μg/mL) and was placed on the constant speed injection pump. The dissolution behavior of PPN was evaluated by dissolution test and the presence of paclitaxel in PPN was detected by X-Ray powder diffraction and differential scanning calorimetry. Effect of PPN on SMMC-7721 cells were studied by cell uptake, cell apoptosis and antitumor study.ResultsThe results of X-ray powder diffraction and differential scanning calorimetry characterization showed that the PPN were in an amorphous state. A dissolution study indicated that PPN have a significantly enhanced dissolution rate of paclitaxel. Moreover, SMMC-7721 tumor cells treated with PPN exhibited a distinctly high uptake rate that promoted cell apoptosis. An in vivo antitumor study demonstrated that PPN had significant antitumor efficacy.ConclusionAll conclusions verified that electrostatic spraying is a potential technology for developing PPN, and PPN can be regarded as a promising treatment for cancer.

Tannic acid-inspired paclitaxel nanoparticles for enhanced anticancer effects in breast cancer cells

Paclitaxel (PTX) is a gold standard chemotherapeutic agent for breast, ovarian, pancreatic and non-small cell lung carcinoma. However, in clinical use PTX can have adverse side effects or inadequate pharmacodynamic parameters, limiting its use. Nanotechnology is often employed to reduce the therapeutic dosage required for effective therapy, while also minimizing the systemic side effects of chemotherapy drugs. However, there is no nanoformulation of paclitaxel with chemosensitization motifs built in. With this objective, we screened eleven pharmaceutical excipients to develop an alternative paclitaxel nanoformulation using a self-assembly method. Based on the screening results, we observed tannic acid possesses unique properties to produce a paclitaxel nanoparticle formulation, i.e., tannic acid-paclitaxel nanoparticles. This stable TAP nanoformulation, referred to as TAP nanoparticles (TAP NPs), showed a spherical shape of ~ 102 nm and negative zeta potential of ~ −8.85. The presence of PTX in TAP NPs was confirmed by Fourier Transform Infrared (FTIR) spectra, thermogravimetric analyzer (TGA), and X-ray diffraction (XRD). Encapsulation efficiency of PTX in TAP NPs was determined to be ≥96%. Intracellular drug uptake of plain drug PTX on breast cancer cells (MDA-MB-231) shows more or less constant drug levels in 2 to 6 h, suggesting drug efflux by the P-gp transporters, over TAP NPs, in which PTX uptake was more than 95.52 ± 11.01% in 6 h, as analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Various biological assays such as proliferation, clonogenic formation, invasion, and migration confirm superior anticancer effects of TAP NPs over plain PTX at all tested concentrations. P-gp expression, beta-tubulin stabilization, Western blot, and microarray analysis further confirm the improved therapeutic potential of TAP NPs. These results suggest that the TAP nanoformulation provides an important reference for developing a therapeutic nanoformulation affording pronounced, enhanced effects in breast cancer therapy.

Knockdown of miR‑935 increases paclitaxel sensitivity via regulation of SOX7 in non‑small‑cell lung cancer.

Sex determining region Y‑box (SOX)7 is a member of the SOX family and is responsible for various developmental processes. As a tumor suppressor, decreased expression of SOX7 has been observed in several cancer types, including non‑small‑cell lung cancer (NSCLC). However, the mechanism underlying SOX7 downregulation and its role in chemoresistance in NSCLC remains poorly understood. In the present study, the inhibition of microRNA (miR)‑935 increased the expression of SOX7 at the mRNA and protein levels in A549 cells. The luciferase reporter assay verified that miR‑935 could directly bind to the 3'untranslated region of SOX7 mRNA to suppress its expression in A549 cells. In addition, the inhibition of miR‑935 enhanced the anticancer effect of paclitaxel, i.e., induced cell growth arrest and apoptosis in A549 cells. It was further observed that the inhibition of miR‑935 decreased the B cell lymphoma (Bcl)‑2 and phosphorylated‑RAC‑α serine/threonine‑protein kinase (AKT) protein levels and increased the Bcl‑2 associated X, apoptosis regulator protein levels, without affecting the AKT levels in the presence of paclitaxel within A549 cells. The findings of the present study validate miR‑935 as a predictor of paclitaxel sensitivity in NSCLC.

Synthesis, Antimicrobial, and Anticancer Activities of a New Series of Thieno[2,3‐d] Pyrimidine Derivatives

A new series from thieno[2,3‐d] pyrimidine derivatives have been synthesized based on 2‐(ethylmercapto)‐4‐mercapto‐6‐phenyl‐5‐pyrimidine carbonitrile, these compounds used in the synthesis of many pyrimidothienopyrimidine derivatives and triazolo[1″,5″:1″,6″]pyrimido[4′,5′:4,5]thieno[2,3‐d] pyrimidine derivatives. The chemical composition of these compounds was confirmed by 1H NMR, 13C NMR, and MS techniques. Some of the synthesized compounds were screened for their antimicrobial and anticancer agent. Compound (9b) showed strong effect on Aspergillus Fumigatus (RCMB 2568), Candida albicans (RCMB 05036), Saphylococcus aureus (RCMB 010010), Bacillis subtilis (RCMB 010067), Salmonella sp. (RCMB 010043), and Escherichia coli (RCMB 010052). Compounds (2) and (5a–k) were evaluated for their IC50 values against two cancer cell lines (MCF‐7 and HeLa cells) in the presence of Paclitaxel as reference material. Compound (5g) showed the highest cytotoxicity against MCF‐7 (IC50 values about 18.87 ± 0.2 μg/mL) cells compared with Paclitaxel (IC50 values about 40.37 ± 1.7 μg/mL). Also, compound (5d) showed the highest cytotoxicity against HeLa (IC50 values about 40.74 ± 1.7 μg/mL) cells compared with Paclitaxel (IC50 values about 45.78 ± 0.8 μg/mL).

Inhibition of glycogen synthase kinase-3 reduces extension of the axonal leading process by destabilizing microtubules in cerebellar granule neurons

Recent studies have uncovered various molecules that play key roles in neuronal morphogenesis. Nevertheless, the mechanisms underlying the neuron-type-dependent regulation of morphogenesis remain unknown. We have previously reported that inhibition of glycogen synthase kinase-3 (GSK3) markedly reduced axonal length of cerebellar granule neurons (CGNs) in a neuron-type-dependent manner. In the present study, we investigated the mechanisms by which the growth of CGN axons was severely suppressed upon GSK3 inhibition. Using time-lapse imaging of cultured CGNs at early morphogenesis, we found that extension of the leading process was severely inhibited by the pharmacological inhibition of GSK3. The rate of somal migration was also reduced with a GSK3 inhibitor in dissociated culture as well as in microexplant culture. In addition, CGNs ectopically expressed with a catalytically inactive mutant of GSK3 exhibited a migration defect in vivo. In axonal leading processes of CGNs, detyrosination and acetylation of α-tubulin, which are known to correlate with microtubule stability, were decreased by GSK3 inhibition. A photoconversion analysis found that inhibition of GSK3 increases the turnover of microtubules. Furthermore, in the presence of paclitaxel, a microtubule-stabilizing reagent, inhibition of GSK3 recovered the axonal leading process extension that was reduced by paclitaxel. Our results suggest that GSK3 supports the extension of axonal processes by stabilizing microtubules, contrary to its function in other neuron-types, lending mechanical insight into neuron-type-dependent morphological regulation.

Deregulation of the spindle assembly checkpoint is associated with paclitaxel resistance in ovarian cancer

BackgroundOvarian cancer is the leading gynecologic cancer diagnosed in North America and because related symptoms are not disease specific, this often leads to late detection, an advanced disease state, and the need for chemotherapy. Ovarian cancer is frequently sensitive to chemotherapy at diagnosis but rapid development of drug resistance leads to disease progression and ultimately death in the majority of patients.ResultsWe have generated paclitaxel resistant ovarian cell lines from their corresponding native cell lines to determine driver mechanisms of drug resistance using gene expression arrays. These paclitaxel resistant ovarian cells demonstrate: (1) Increased IC50 for paclitaxel and docetaxel (10 to 75-fold) and cross-resistance to anthracyclines (2) Reduced cell apoptosis in the presence of paclitaxel (3) Gene depletion involving mitotic regulators BUB1 mitotic checkpoint serine/threonine kinase, cyclin BI (CCNB1), centromere protein E (CENPE), and centromere protein F (CENPF), and (4) Functional data validating gene depletion among mitotic regulators.ConclusionsWe have generated model systems to explore drug resistance in ovarian cancer, which have revealed a key pathway related to the spindle assembly checkpoint underlying paclitaxel resistance in ovarian cell lines.

Novel post-transcriptional and post-translational regulation of pro-apoptotic protein BOK and anti-apoptotic protein Mcl-1 determine the fate of breast cancer cells to survive or die.

Deregulation of apoptosis is central to cancer progression and a major obstacle to effective treatment. The Bcl-2 gene family members play important roles in the regulation of apoptosis and are frequently altered in cancers. One such member is pro-apoptotic protein Bcl-2-related Ovarian Killer (BOK). Despite its critical role in apoptosis, the regulation of BOK expression is poorly understood in cancers. Here, we discovered that miR-296-5p regulates BOK expression by binding to its 3’-UTR in breast cancers. Interestingly, miR-296-5p also regulates the expression of anti-apoptotic protein myeloid cell leukemia 1 (Mcl-1), which is highly expressed in breast cancers. Our results reveal that Mcl-1 and BOK constitute a regulatory feedback loop as ectopic BOK expression induces Mcl-1, whereas silencing of Mcl-1 results in reduced BOK levels in breast cancer cells. In addition, we show that silencing of Mcl-1 but not BOK reduced the long-term growth of breast cancer cells. Silencing of both Mcl-1 and BOK rescued the effect of Mcl-1 silencing on breast cancer cell growth, suggesting that BOK is important for attenuating cell growth in the absence of Mcl-1. Depletion of BOK suppressed caspase-3 activation in the presence of paclitaxel and in turn protected cells from paclitaxel-induced apoptosis. Furthermore, we demonstrate that glycogen synthase kinase (GSK3) α/β interacts with BOK and regulates its level post-translationally in breast cancer cells. Taken together, our results suggest that fine tuning of the levels of pro-apoptotic protein BOK and anti-apoptotic protein Mcl-1 may decide the fate of cancer cells to either undergo apoptosis or proliferation.

Abstract 1917: AXL inhibition in ovarian cancer stem-like cells increases chemo-sensitivity

Abstract Cancer stem-like cells (CSCs), a small population of cancer cells with regenerative potential, may lead to the initiation and progression of secondary tumors. Long-term chemotherapeutic drug treatment can also result in the generation of a drug resistant population of cancer stem cells. In this study we have isolated CD44+ and CD117+ enriched ovarian cancer stem-like cells from primary cultured ascites cells removed from ascites fluid of naïve ovarian cancer patients. AXL, a type I receptor tyrosine kinase family member, is found to be over-expressed in ovarian cancer stem-like cells. Cell viability assays showed that ovarian CSCs are chemo-resistant to concentration dependent paclitaxel treatment. AXL was inhibited using a R428 and cell viability assays and apoptotic assays in the presence of paclitaxel were performed, which made the CSCs chemo sensitive. Si-RNA based inhibition of AXL also displayed a similar pattern of improving the sensitivity of the stem-like cells to the chemotherapeutic drug. PI3-kinase/Akt signaling pathway has also been shown to be involved in decreasing the cell viability during the inhibition of AXL. In conclusion, this study establishes the role of AXL, a receptor tyrosine kinase, as one of the key proteins influencing the chemo resistance in ovarian cancer stem-like cells. Citation Format: Jin-Young Kim, Hyewon Chung, So-Jin Shin, Eunyoung Ha, Chi-Heum Cho. AXL inhibition in ovarian cancer stem-like cells increases chemo-sensitivity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1917. doi:10.1158/1538-7445.AM2017-1917

Abstract 1051: Preclinical analyses of synergistic effect of eribulin and paclitaxel for triple-negative breast cancer

Abstract Purpose: There is an urgent need to develop novel therapeutic strategies for triple negative breast cancer (TNBC). To explore the antitumor effect of combination of eribulin (ERI) and paclitaxel (PTX) for TNBC, we conducted preclinical experiments. Materials & methods: Combinational effects of ERI and PTX were analyzed both in vitro and in vivo using two TNBC cell lines (MDA-MB-231, Hs578T). Results: When ERI was added simultaneously with PTX to TNBC cells, the sensitivity to PTX was increased synergistically. On the other hand, synergistic increase of sensitivity to ERI was observed in the presence of PTX. When the TNBC cells were treated with each drug subsequently, pretreatment with ERI for 96 hours enhanced the sensitivity to PTX administrated subsequently. In contrast, pretreatment of TNBC cells with PTX enhanced the sensitivity to the subsequently administrated ERI. When the TNBC cells were treated with ERI, the expression of epithelial marker, E-cadherin was increased, while the expression of mesenchymal markers, pSmad2, ZEB1, Slug, and vimentin were decreased. In contrast, when the cells were treated with PTX, the expressions of mesenchymal markers were increased. When epithelial-mesenchymal transition (EMT) was induced by TGF-β in the TNBC cells, the sensitivity to ERI was enhanced, while TGF-β receptor inhibitor (LY2157299) reduced the sensitivity to ERI. Furthermore, knockdown of ZEB1 by small interfering RNA conferred resistance to ERI in both TNBC cell lines. In the mouse xenograft model bearing MDA-MB-231, ERI plus PTX combination therapy significantly inhibited tumor growth compared with either PTX or ERI monotherapy. Furthermore, prior treatment with ERI significantly enhanced the antitumor activity of PTX in the mouse xenograft model. Conclusions: Our findings demonstrate an EMT-mediated synergistic antitumor effect by combination of two tubulin inhibitors. This combination therapy may serve as a novel therapeutic strategy for TNBC. Citation Format: Takaaki Oba, Ken-ichi Ito. Preclinical analyses of synergistic effect of eribulin and paclitaxel for triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1051. doi:10.1158/1538-7445.AM2017-1051

Snail-Induced Epithelial-to-Mesenchymal Transition Enhances P-gp-Mediated Multidrug Resistance in HCC827 Cells

Overexpression and activation of P-glycoprotein (P-gp), which mediates efflux transport of various anticancer drugs in cancer cells, is associated with multidrug resistance (MDR). On the other hand, malignant cancer cells frequently undergo epithelial-to-mesenchymal transition (EMT), thereby acquiring high migratory mobility and invasive ability. Snail is a transcriptional factor that represses multiple other factors, and its overexpression is a trigger of EMT. Because both P-gp and Snail are involved in malignant evolution of cancer, in this work, we evaluated whether EMT induced by overexpression of Snail influences P-gp expression and activity. Snail-overexpressing cells showed downregulation of epithelial markers, E-cadherin, occludin, and claudin-1, and upregulation of mesenchymal markers, vimentin and ZEB1. Although Western blot analysis showed that P-gp expression levels were similar in Mock and Snail-overexpressing cells, the results of P-gp functional assays with P-gp substrates rhodamine123 and paclitaxel indicated that P-gp is activated in Snail-overexpressing cells. Indeed, Snail-overexpressing cells showed greater viability than Mock cells in the presence of paclitaxel. We observed caveolin-1 dephosphorylation and decreased growth factor receptor-bound protein 2 (GRB2) expression in Snail-overexpressing cells. These findings suggest a novel pathway leading to cancer MDR, in which Snail induces EMT concomitantly with a decrease in GRB2-mediated caveolin-1 phosphorylation, resulting in activation of P-gp.

Basic helix-loop-helix transcription factor DEC2 functions as an anti-apoptotic factor during paclitaxel-induced apoptosis in human prostate cancer cells.

The functions of basic helix-loop-helix (bHLH) transcription factor-differentiated embryonic chondrocyte (DEC)1 (BHLHE40) and 2 (BHLHE41) are involved in various fields such as circadian rhythms, immune responses, cell proliferation, hypoxia reaction as well as malignant tumors. Previous findings showed that DEC served as apoptosis regulators of various cancer cell lines. However, little is known regarding the expression of DEC1 and DEC2 in prostate cancer cells. The present study aimed to examine the roles of DEC1 and DEC2 in human prostate cancer DU145 and PC-3 cells that were treated with paclitaxel. The expression of DEC1 and DEC2 was decreased in DU145 cells but was increased in PC-3 cells when treated with paclitaxel. DU145 cells were more sensitive to paclitaxel than PC-3 cells since the amount of cleaved poly(ADP-ribose) polymerase (PARP) reached its peak at 50 μM of paclitaxel in DU145 cells but at 100 μM in PC-3 cells. In addition, the amount of cleaved PARP was decreased by DEC1 siRNA, while it was increased by DEC2 siRNA in the presence of paclitaxel. Although DEC2 overexpression slightly inhibited cleaved PARP in the two cell lines, the effects of DEC1 overexpression on apoptosis remain to be determined. In conclusion, DEC1, at least partly, exerted a pro-apoptotic effect, whereas DEC2 exerted an anti-apoptotic effect in paclitaxel-induced apoptosis of human prostate cancer cells.