Cytotoxic Effects Of Taxol Research Articles

Abstract 195: Evaluation of the cell surface binding of phycocyanin and associated mechanisms causing cell death in prostate cancer cells

Abstract Plant and microbial metabolites are constantly explored to identify novel therapeutics with promising potential for treating diseases such as cancer. Marine-derived compounds are also tapped frequently for their efficacy in treating cancers and are used both in mono and combination therapies. The potential of cyanobacteria (blue-green algae) as the source of anticancer agents has been explored for many decades and, as a result of continuing efforts, several compounds have emerged as templates for the development of new anticancer drugs from these microorganisms. The C-phycocyanin (C-PC) tested in our experiments was derived from the cyanobacteria Limnothrix sp., strain 37-2-1, which is found abundantly in Florida’s Everglades. In our previous studies, this fluorescent compound was found to potentiate the cytotoxic effects of Taxol and Topotecan. In LNCaP prostate cancer cells, C-PC was able to induce apoptosis by itself through activation of the apoptotic pathway and completing DNA fragmentation. It was originally anticipated that C-PC might penetrate the cell membrane to induce mitochondrial damage and trigger the apoptotic process through activations of caspases. In order to verify this possibility, experiments were conducted to determine the uptake of C-PC using LNCaP cells. When we incubated the cells with C-PC at the concentrations of 250 and 500 µg/mL for 12 hrs and assessed the cellular uptake by capturing the fluorescence signals at the wavelength of 605 nm, using a fluorescence microscope, the signals were observed only with the periphery of the cells. Furthermore, with subsequent washes using PBS, the fluorescence signal that was seen to be associated with the plasma membrane was reduced gradually and was removed completely after the 3rd wash without any signs of penetration into the cytoplasm. The binding of C-PC to the plasma membrane was very transient and quickly dissociated at room temperature. However, after incubating the cells with the same concentrations of C-PC, there was up-regulation of proapoptotic markers such as p53 and p21 and as a result, the cells showed a significant reduction (>65%) in viability. So far, our results suggest that the cytotoxicity towards LNCaP cells might have been triggered by the binding of C-PC to the cell membrane receptors such as FasR, TRAIL-R, TNF-R, which may be linked to the mediators of extrinsic and intrinsic apoptotic signals. Hence, our findings are significant for explaining some of the apoptotic events triggered by C-PC. However, additional studies are required to identify the actual receptors involved in triggering the pathway. (The support from the Royal Dames of Cancer Research Inc., Ft. Lauderdale, Florida is gratefully acknowledged). Citation Format: Paramjot Kaur, Sivanesan Dhandayuthapani, Shona Joseph, Syed Hussain, Miroslav Gantar, Appu Rathinavelu. Evaluation of the cell surface binding of phycocyanin and associated mechanisms causing cell death in prostate cancer cells [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 195. doi:10.1158/1538-7445.AM2017-195

Abstract 2924: Suppressing SET reactivates PP2A function in EGFR wide-type NSCLC and synergizes with taxol to exert anti-cancer effects

Abstract Background: Non-small cell lung cancer (NSCLC) is the leading cause of cancer-associated death in the world. Conventional chemotherapy is the standard-of-care for majority of patients with advance NSCLC and tyrosine kinase inhibitors of epithelial growth factor receptor (EGFR) only benefit patients with tumor containing specific mutation forms of EGFR. However, high disease recurrence rate after currently available therapeutics limited patient's survival. Therefore, there is a timely need to improve current treatment for patients with NSCLC, especially those with EGFR wide type tumors. Protein phosphatase 2A (PP2A) is an important tumor suppression whose function is inhibited in tumor tissue by the appearance of SET. In current study, we showed that inhibiting SET binding to PP2A by a novel small molecular compound significantly improved the chemosensitivity of EGFR wide-type NSCLC cells. Method: EGFR wide-type NSCLC cell lines, including A549, H358 and H460, were treated with taxol and a novel quinzoline derivative, PA, which was designed and developed to interrupt the binding of SET to PP2A. Apoptosis of cancer cell, signal transduction and phosphatase activity were analyzed after treatments. Combination index (CI) was applied to determine the synergistic effects of PA and taxol. Co-immunoprecipitation (co-IP) and proximity ligation assay (PLA) were used to identify in vivo binding between SET and PP2A. In vivo anti-tumor effects of treatment containing PA and taxol were also determined in A549 xenografted mice. Results: After treating the cancer cells with PA and taxol, apoptosis of cancer cells, in concordance with enhancing PP2A-dependent p-Akt downregulation, were observed in a dose-dependent manner in all EGFR wide-type NSCLC cell lines. CI determined by the results of sub-G1 analysis confirmed the synergy between PA and taxol. Overexpression of Akt and inhibition of PP2A diminished the therapeutic effects of this combination. By two different strategies, co-IP and PLA, we found that this combination treatment inhibited the association of SET and PP2A within lung cancer cells. When overexpression SET in treated cancer cells, the therapeutic effects of this combination were abolished. The anti-tumor effects of treatment combining PA and taxol were also validated in A549 xenografted mice. Our data suggested that PP2A inactivation determines the drug sensitivity of taxol in lung cancer cells, and by interfering the binding of SET and PP2A, PA significantly promote PP2A activity and increase the cytotoxic effects of taxol in EGFR wide-type NSCLC. Conclusion: By interfering the binding of SET to PP2A, the novel PP2A enhancer, PA, is shown to reactivate PP2A and work synergistically with taxol for the treatment of EGFR wide-type NSCLC. Citation Format: Man-Hsin Hung, Chung-Wai Shiau, Yung-Jen Hsiao, Hui-Chuan Yu, Wei-Tien Tai, Chun-Yu Liu, Cheng-Yi Wang, Kuen-Feng Chen. Suppressing SET reactivates PP2A function in EGFR wide-type NSCLC and synergizes with taxol to exert anti-cancer effects. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2924. doi:10.1158/1538-7445.AM2015-2924

Abstract 5543: Elucidating the cytotoxic effects of taxol,camptothecin and Lobostemon fruticosus extracts on non-small cell lung cancer

Abstract Lung cancer is reportedly the most common form of cancer worldwide, with a 13-15% occurrence of all known cancers being reported daily. Lung cancer is also the most deadly form of cancer as it has been observed to be resistant to most therapeutic treatments and it demonstrates a metastasis within lymph nodes. An alternative approach is to identify the cytotoxic effects of non-invasive medicinal plant extracts on NSCLC. Thus the aim of the study was to compare the cytotoxic effects of the invasive anti-cancer drugs, taxol and camptothecin, with less invasive plant extracts of L. fruticosus on cell line A549. Cells seem to show a degree of cell death after treatment however some degree of cells still remain viable indicating usefulness in chemotherapy. The following techniques were used, exCELLigence RTCA, Cell cycle, Annexin V apoptosis analysis and LC-MS to identify the compound. Cells treated with camptothecin, Methanol and butanol extracts indicate some degree of early apoptosis which was indicative of little to no DNA fragmentation. Cell cycle arrest was observed in both camptothecin and taxol treated cells, however there was little evidence to suggest the same for L. Fruticosus extracts as there was a high degree of cell death that was observed during the cell cycle analysis. Apoptotic genes that were found in A549 treated cells upregulated in the absence of p53. Phytochemical screening of the L. Fruticosus plant extracts indicated that the plant possesses compounds that display apoptotic activity. These findings suggest that camptothecin, taxol and extract of L. fruticosus display cytotoxic activity on A549 cells. The upregulation of genes in absence of p53 seem to suggest that treatments induce apoptosis using an alternative apoptotic pathway. Note: This abstract was not presented at the meeting. Citation Format: Lesetja Raymond Motadi, Lungile Ndlovu. Elucidating the cytotoxic effects of taxol,camptothecin and Lobostemon fruticosus extracts on non-small cell lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5543. doi:10.1158/1538-7445.AM2015-5543

Cytotoxic effects of alcoholic extract of dorema glabrum seed on cancerous cells viability.

In the present study cytotoxic effects of the alcoholic extract of Dorema Glabrum seed on viability of WEHI-164 cells, mouse Fibrosarcoma cell line and L929 normal cells were compared with the cytotoxic effects of Taxol (anticancer and apoptosis inducer drug). To find out the plant extract cytotoxic effects, MTT test and DNA fragmentation assay, the biochemical hallmark of apoptosis were performed on cultured and treated cells. According to the findings the alcoholic extract of Dorema Glabrum seed can alter cells morphology and because of chromatin condensation and other changes they shrink and take a spherical shape, and lose their attachment too. So the plant extract inhibits cell growth albeit in a time and dose dependent manner and results in degradation of chromosomal DNA. Our data well established the anti-proliferative effect of methanolic extract of Dorema Glabrum seed and clearly showed that the plant extract can induce apoptosis and not necrosis in vitro, but the mechanism of its activities remained unknown. These results demonstrated that Dorema Glabrum seed might be a novel and attractive therapeutic candidate for tumor treatment in clinical practices.

Investigating Apoptotic Effects of Methanolic Extract ofDorema glabrumSeed on WEHI-164 Cells

We aimed to investigate the apoptotic effects of the methanolic extract of Dorema glabrum seed on WEHI-164, cancerous cells in comparison with L929, normal cells and compared them with the cytotoxic effects of Taxol. So, MTT test and DNA fragmentation assay were performed on cultured and treated cells. Also electrophoresis which was followed by immunoblotting was done to survey the production of Caspase-3 and Bcl2 proteins, and to inquire into their relative genes expression, RT-PCR was used. According to our findings, the methanolic extract of Dorema glabrum seed can alter cells morphology as they shrink and take a spherical shape and lose their attachment too. So, the plant extract inhibits cell growth albeit in a time- and dose-dependent manner and results in degradation of chromosomal DNA. Induction of apoptosis by the plant extract was proved by the reduction of pro-Caspase-3 and Bcl2 proteins and increase in Caspase-3 gene expression and decrease in that of bcl2 too. Our data well established the antiproliferative effect of methanolic extract of Dorema glabrum seed and clearly showed that the plant extract can induce apoptosis and not necrosis in vitro. These results demonstrated that Dorema glabrum seed might be a novel and attractive therapeutic candidate for tumor treatment.

Abstract 2745: INK128, a TORC1/2 kinase inhibitor, enhances the efficacy of cytotoxic therapies in endometrial tumor models

Abstract Background: The mammalian target of rapamycin (mTOR), which comprises two protein complexes, TORC1 and TORC2, regulates tumor cell growth, metabolism and motility. In endometrial cancer, the mTOR pathway is aberrantly activated by constitutive mitogen stimuli, such as FGFR2 and multiple genetic mutations such as PIK3CA, PIK3R1/2, PTEN and LKB1. The activation of multiple signaling pathways, cross-feedback and redundancy of these pathways led us to explore the combination of mTOR kinase inhibitor with chemotherapeutic agents for achieving maximal efficacy in preclinical mouse models of endometrial cancer. Results: INK128 is a potent and selective TORC1/2 inhibitor with excellent drug-like properties currently advancing in clinical development. INK128 inhibits endometrial tumor cell proliferation in vitro and displays tumor growth inhibition in endometrial tumor models. In most instances, the anti-tumor activity of INK128 is cytostatic compared to the cytotoxic effect of taxol and carboplatin. In endometrial tumor cells of diverse genetic backgrounds, combining INK128 with taxol resulted in a synergistic inhibition of tumor cell proliferation, sustained suppression of PI3K/AKT/mTOR pathway activity, skewed cell cycle and an increase in apoptosis. INK128 decreased the expression of anti-apoptotic protein MCL-1 and therefore mechanistically enhanced taxol-triggered apoptosis. In endometrial mouse tumor models with PTEN and FGFR2 mutations, the combination induced marked tumor regression and significantly delayed tumor re-growth upon discontinuation of the treatment compared to taxol treatment alone. The combination therapy was well-tolerated and the enhanced anti-tumor efficacy correlated with mechanism-based inhibition of several TORC1 and TORC2 pharmacodynamic markers and induction of apoptosis in vivo. Additionally, combining INK128 with taxol or carbotaxol resulted in tumor regression in taxol-resistant endometrial tumor models. The opportunity of optimizing dose and schedule combination regimens as well as biomarkers predicting sensitivity/resistance to INK128/taxol combination will be discussed. Conclusion: The combination of mTOR kinase inhibitors with chemotherapeutic agents is a compelling strategy to improve therapeutic outcome and to overcome chemo-resistance for tumor types with aberrant activation of the PI3K/mTOR pathway such as endometrial cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2745. doi:1538-7445.AM2012-2745

Presence of Circadian oscillation of Multidrug Resistance Gene 1 in KB-C2 cell line

Many physiological, biochemical and behavioral processes are under circadian regulation, which is generated by an internal time-keeping mechanism referred to as biological clock in almost all organisms from bacteria to mammals. Although the substantial evidences that the circadian clock could modulate the morbidity and efficacy of anticancer therapy have been proposed, underlying mechanisms for chronotherapy has been only poorly elucidated, and it has not been popular in clinic. The aim of this study was to determine the relationship between the expression of P-glycoprotein (P-gp)/MDR1, which is one of the important molecules in anti-cancer drug resistance, and circadian rhythm in KB-C2 cells. The present study demonstrated that both MDR1 expression level and its promoter activity oscillated after treatment with high concentration of fetal bovine serum. Moreover, cytotoxic effect of taxol were dependent on the fluctuated levels of MDR1. These results suggest that the circadian rhythm of MDR1 may have an influential effect on cytotoxicity of anti-cancer drug and could be available for chemotherapy in clinic.

Protective Effects of Glucocorticoids on Taxol-Induced Cytotoxicity in Human Leukemia Hl-60 Cells

Although the therapeutic actions of glucocorticoids are largely attributed to anti-inflammatory and immunosuppressive effects, they have been implicated in enhancing tissue and cellular protections. In this study, we examined whether glucocorticoids including dexamethasone (Dex) and hydroxy-cortisone could diminish the cytotoxic effects of anti-microtubule agents including taxol (paclitaxel), microtubule stabilizing agent, and colchicine, microtubule disrupting agent, on human leukemia HL-60 cells. Taxol or colchicine decreased the viability of HL-60 cells in a dose-dependent manner. However, micromolar concentrations of glucocorticoids rendered HL-60 cells resistant against the cytotoxic activity of anti-microtubule agents. Pretreatments of the glucocorticoids were more effective than simultaneous treatments with antimicrotuble agents. The fact that actinomycin D or cycloheximide reversed the cytoprotective effects of glucocorticoids on cytotoxicities in HL-60 cells induced by antirnicrotuble agents suggests glucocorticoids cytoprotection might be mediated via newly synthesized protein. Collectively, these data showed that micromolar concentrations of dexamethasone or hydrocortisone could attenuate the cytotoxic effects of taxol or colchicine on human leukemia HL-60 cells via protein synthesis.

Taxol induces concomitant hyperphosphorylation and reorganization of vimentin intermediate filaments in 9l rat brain tumor cells

Taxol, a microtubule stabilizing agent, has been extensively investigated for its antitumor activity. The cytotoxic effect of taxol is generally attributed to its antimicrotubule activity and is believed to be cell cycle dependent. Herein, we report that taxol induces hyperphosphorylation and reorganization of the vimentin intermediate filament in 9L rat brain tumor cells, in concentration- and time-dependent manner. Phosphorylation of vimentin was maximum at 10−6 M of taxol treatment for 8 h and diminished at higher (10−5 M) concentration. Enhanced phosphorylation of vimentin was detectable at 2 h treatment with 10−6 M taxol and was maximum after 12 h of treatment. Taxol-induced phosphorylation of vimentin was largely abolished in cells pretreated with staurosporine and bisindolymaleimide but was unaffected by H-89, KT-5926, SB203580, genistein, and olomoucine. Thus, protein kinase C may be involved in this process. Hyperphosphorylation of vimentin was accompanied by rounding up of cells as revealed by scanning electron microscopy. Moreover, there was a concomitant reorganization of the vimentin intermediate filament in the taxol-treated cells, whereas the microtubules and the actin microfilaments were less affected. Taken together, our data demonstrate that taxol induces hyperphosphorylation of vimentin with concomitant reorganization of the vimentin intermediate filament and that this process may be mediated via a protein kinase C signaling pathway. J. Cell Biochem. 68:472–483, 1998. © 1998 Wiley-Liss, Inc.

Taxol induces concomitant hyperphosphorylation and reorganization of vimentin intermediate filaments in 9l rat brain tumor cells

Taxol, a microtubule stabilizing agent, has been extensively investigated for its antitumor activity. The cytotoxic effect of taxol is generally attributed to its antimicrotubule activity and is believed to be cell cycle dependent. Herein, we report that taxol induces hyperphosphorylation and reorganization of the vimentin intermediate filament in 9L rat brain tumor cells, in concentration- and time-dependent manner. Phosphorylation of vimentin was maximum at 10(-6) M of taxol treatment for 8 h and diminished at higher (10(-5) M) concentration. Enhanced phosphorylation of vimentin was detectable at 2 h treatment with 10(-6) M taxol and was maximum after 12 h of treatment. Taxol-induced phosphorylation of vimentin was largely abolished in cells pretreated with staurosporine and bisindolymaleimide but was unaffected by H-89, KT-5926, SB203580, genistein, and olomoucine. Thus, protein kinase C may be involved in this process. Hyperphosphorylation of vimentin was accompanied by rounding up of cells as revealed by scanning electron microscopy. Moreover, there was a concomitant reorganization of the vimentin intermediate filament in the taxol-treated cells, whereas the microtubules and the actin microfilaments were less affected. Taken together, our data demonstrate that taxol induces hyperphosphorylation of vimentin with concomitant reorganization of the vimentin intermediate filament and that this process may be mediated via a protein kinase C signaling pathway.

Comparative in vitro cytotoxic effects of taxol and its major human metabolite 6?-hydroxytaxol

Comparative in vitro cytotoxic effects of taxol and its major human metabolite 6?-hydroxytaxol

Taxol in combination with acute and low dose rate irradiation

Taxol is an investigational antineoplastic agent which acts by stabilizing microtubules, thereby preventing normal mitosis. It is believed to block cells in the G 2/M phase of the cell cycle. The drug is a natural product isolated from the yew, Taxus brevifolia. We have used a cell line derived from human cervical carcinoma to investigate the combination of Taxol with high and low dose rate 137Cs irradiation. An additive effect for Taxol plus radiation was observed; supra-additivity or synergism is not suggested by our data. In the cell line studied, drug concentrations that accumulate cells to some degree in the G 2/M phase of the cycle lead to cell lethality, so that no radiosensitizing effect is possible. We have also shown that the cytotoxic effect of Taxol is not limited to the G 2/M phase of the cell cycle. In the clinic, Taxol shows promise both as a chemotherapeutic agent and as a possible adjunct to radiation. The present work demonstrates the need for further studies of Taxol plus radiation with a variety of human cell lines of normal and malignant origin.

A saturation threshold for taxol cytotoxicity in human glial and neuroblastoma cells

The cytotoxic effects of taxol at concentrations of 0.001-1.0 microgram/ml were determined in two human glioblastoma multiforme, two neuroblastoma and two primitive neuroectodermal tumor cell lines. The neuroectodermal cell lines were established from previously treated patients, while the glioblastomas were from untreated patients. At exposure durations of 1, 4 and 24 h there was an inverse taxol concentration-survival relationship for all six cell lines as measured by the MTT method. Significant differences in sensitivity to taxol among these cell lines were observed; the most resistant cell line SK-N-FI is characterized by very high levels of MDR1 expression and the most sensitive SK-N-AS by very low levels. An additional level of complexity concerns a saturation threshold for taxol-induced cytotoxic effects which when reached precludes additional effects of prolonged or additional exposure. Tumors of the brain and peripheral nervous system appear to be sensitive to taxol. However, dosage necessary to maximize cytocidal effects in tumors requires knowledge of at least the range of each tumors constitutive sensitivity to taxol and a way to optimize drug delivery.

CEPHALOMANNINE AND 10-DEACETYLTAXOL CYTOTOXICITY IN HUMAN GLIAL AND NEUROBLASTOMA CELL-LINES

The cytotoxic effects of taxol, 10-deacetyltaxol, and cephalomannine at concentrations of 0.1 mug/ml to 10.0 mug/ml for one and 24 hours exposure were determined in two human glioblastoma multiforme and two neuroblastoma cell lines using the MTT method. The neuroblastoma cell lines were established from previously treated patients, while the glioblastomas were from untreated patients. There was a proportionate concentration-toxicity relationship for all four cell lines. The neuroblastoma SK-N-FI was consistently the most resistant to all three drugs. The order of potency after a one hour exposure was taxol, 10-deacetyltaxol and cephalomannine. Cephalomannine contained 1.5% taxol impurity and 10-deacetyltaxol, 4.5% taxol hence the contribution of taxol to these substances' toxic effects was minimal. We conclude that tumors of the central and peripheral nervous system are sensitive to 10-deacetyltaxol and cephalomannine and these drugs are less toxic than taxol but remain within a therapeutic range.