Rapamycin And Cisplatin In Breast Cancers

Rapamycin And Cisplatin In Breast Cancers Recent gene expression profiling has identified five breast cancer subtypes, of which the basal-like breast cancers are the most aggressive and possess serious clinical challenges as there are currently no targeted therapies available. Although there is increasing evidence that these tumors confer specific sensitivity to cisplatin, its success is often compromised due to its dose-limiting nephrotoxicity and development of drug resistance. To overcome this limitation, our focus is to maximize the benefits associated with cisplatin therapy through drug combination strategies. Using a well-validated kinase inhibitors library, we showed that inhibition of mTOR, TGFà ¯Ã‚ Ã‚ ¢RI, NFà ¯Ã‚ Ã‚ «B, PI3K/AKT and MAPK pathway sensitized the basal-like MDA-MB-468 cells to cisplatin treatment. Further evaluation demonstrated that combination of mTOR inhibitor, rapamycin, and cisplatin generated significant drug synergism specifically in basal-like cells (MDA-MB-468, MDA-MB-231 and HCC1937). Th ese synergistic effects were not observed in the luminal-like T47D and MCF-7 cells. We further showed that the synergistic effects of rapamycin and cisplatin is mediated through p73. Treatment of rapamycin induced p73 upregulation and synergized cisplatin activity through activation of the p73 pathway. Depletion of endogenous p73 in basal-like cells abolished these synergistic effects suggesting that p73 is required for the rapamycin and cisplatin synergism. In conclusion, combination of mTOR inhibitors and cisplatin may be a useful therapeutic strategy in basal-like breast cancers. INTRODUCTION Recent identification of novel breast cancer subtypes with distinct biological features promises a more specific, effective and less toxic therapies to the patients. Through gene profiling, breast cancer can be categorized into five different subtypes with distinct clinical outcome. The five major subtypes of breast cancer are luminal A, luminal B, human epidermal growth factor receptor-2 (HER2) overexpressing, normal-like and basal-like breast cancer [1, 2]. Of particular important is the basal-like breast cancer which accounts for 15-20% of breast cancers overall and confers a remarkably poor prognosis compared to other subtypes. Majority of basal-like breast cancers exhibit a triple-negative phenotype, characterized by the lack of expression of estrogen receptor (ER), progesterone receptor (PR) or HER2 amplification, and often have high frequency of p53 mutation [3, 4]. Due to the lack of expression of these receptors (ER, PR and HER2), patients with basal-like breast cancers usua lly do not response to hormonal therapy, Herceptin or chemotherapy [5, 6]. As a consequence, the mortality rate of basal-like breast cancer is relatively high in comparison with the non-basal subtype [1]. Numerous clinical studies are currently ongoing to identify novel therapy for treatment of basal-like breast cancers. These include the use of specific targeted therapeutic agents (e.g. Cetuximab, Dasatinib, Bevacizumab, Abraxane and Erlotinib) or conventional chemotherapeutics agents (e.g. cisplatin, doxorubicin, and paclitaxel), either as single agent or in combination, as first line therapy for basal-like breast cancers [7-9]. Cisplatin, a chemotherapeutic agent not commonly used for breast cancer, come to light in the management of basal-like breast cancer on account of evidence that breast cancer cells with basal-like phenotype confer a selective sensitivity towards cisplatin as compared to other chemotherapeutic agents. A variety of evidence suggests that basal-like breast cancers may share defects in BRCA1-associated pathways, of which DNA repair mechanism has been compromised [10]. Indeed, recent clinical studies have demonstrated the clear advantage of cisplatin in treatment of basal-like breast cancer compared to other chemotherapeutic agents [11, 12]. Nevertheless, dose-limiting toxicity including nephrotoxicity, neurotoxicity and ototoxicity have withold the wide-spread use of cisplatin in treating breast cancers in the clinic. To address this problem, we developed a high-throughput screening assay to rapidly identify new therapeutic agents that could synergize the antitumor effects of cisplatin in basal-like breast cancers. Through the use of a small chemical library that targets some of the most relevant oncogenic pathways in basal-like breast cancer, we show that inhibition of mTOR by rapamycin incurred a specific synergistic effect with cisplatin in basal-like breast cancer cells. This synergistic effect is mediated in part through the induction and activation of p73 in the presence of rapamycin and cisplatin, respectively. Together, our findings demonstrate evidence of a synergistic relation between rapamycin and cisplatin in both inhibition of cell growth and induction of apoptosis. This suggests that rapamycin and cisplatin may be a rational combination of a targeted therapy for the refractory basal-like breast cancers. Materials and Methods Cell lines and cell culture The human breast carcinoma cell lines MCF-7, T47D, MDA-MB-231, MDA-MB-468 and HCC1937 were obtained from the American Type Culture Collection (Manassas, VA) and maintained in RPMI 1640 medium containing 10% fetal bovine serum (FBS), 100 IU/ml penicillin and 100 ÃŽÂ ¼g/ml streptomycin (Sigma-Aldrich, St. Louis, MO, USA) at 37 °C with 5% CO2. MTT cell proliferation assay Dose-response curves and IC50 values were determined using the methyl thiazolyl tetrazolium (MTT) cell viability assay as described previously [4, 13]. Cells were seeded into 96-well plates for 24 hours at a density of 5 ÃÆ'- 103 cells/well. Serial drug dilutions were prepared in medium immediately before each assay, and viable cell masses following 3 days of drug exposure were determined by cell-mediated MTT reduction. Cell growth as well as drug activity was determined by measuring absorbance at 550 nm using an Anthos systems plate reader. Construction of IC50 mean graph The IC50 mean graph was constructed as defined by the Developmental Therapeutics Program of the National Cancer Institute (http://dtp.nci.nih.gov). The mean graph consists of positive (more sensitive) and negative (less sensitive) delta values, generated from a set of IC50 values by using a three-step calculation. The IC50 values for each of cell line against the tested compound were converted to log(IC50) values. For each tested compound, the log(IC50) values are averaged. Finally, the individual IC50 value is then subtracted from the average to generate the delta value. Positive delta values project to the right of the vertical line and represent cellular sensitivities to the test agent that exceed the mean. Negative values project to the left and represent cell line sensitivities to the test agent that are less than the average value. Library screening The Inhibitor Select„ ¢ chemical library which consists of 160 well-characterized, cell-permeable inhibitors was purchased from EMD Chemicals, USA. MDA-MB-468 cells at the logarithmic phase of growth were seeded into 96-well plate at a density of 5 ÃÆ'- 103 cells/well. Each compound was added to a final concentration of 10  µM in the absence or presence of 1  µM cisplatin. Plates were incubated for 72h at 37 °C. Cell proliferation was examined using MTT assay as described previously. Combination treatments that induce growth inhibition higher than those of the same doses used alone (p Drug interaction analysis Drug combination analysis was performed by using the method as described by Chou and Talalay [14]. Briefly, cells were seeded at 5 ÃÆ'- 103 cells/well in 96-well plates and treated with various concentrations of cisplatin and compound alone or in combination for 72h. Cell proliferation was measured in each well by MTT assay. Multiple drug dose-effect calculations and the combination index plots were generated using Calcusyn software (Biosoft, Cambridge, UK). Combination index, CI 1 indicate synergism, additive effect and antagonism, respectively. Apoptosis assays Quantitation of apoptosis by annexin V/PI staining was performed as described previously [3, 4]. Briefly, both floating and attached cells were collected 72h after drug treatments. Apoptotic cell death was determined using the BD ApoAlert annexin V-FITC Apoptosis Kit (BD Biosciences, USA) according to the manufacturers instructions, and cells were analyzed on a FACSCalibur flow cytometer using CellQuest Pro software (version 5.1.1; BD Biosciences, USA). Quantitative PCR (qPCR) analysis Total RNA from cells was extracted using Qiagen RNA isolation kit (Qiagen, Valencia, CA, USA) according to the manufacturers protocol. First-strand cDNA was synthesized from total RNA using random hexamer primers and the SuperScript II system for RT-PCR (Invitrogen, Carlsbad, USA). Gene expression levels were measured by qPCR using the iQ SYBR Green Supermix reagent and an Biorad iQ5 real-time PCR detector system (Bio-Rad, Richmond, CA, USA). Data analysis was performed using Opticon Monitor Analysis Software V1.08. The expression of each gene was normalized to ÃŽÂ ²2M as a reference. The relative copy numbers were calculated from an 8-point standard curve generated from a 10-fold serial dilution of full-length cDNA constructs as described previously [3, 4]. Specific forward and reverse primer sequences are as follows : TAp73fwd, 5-GCACCACGTTTGAGCACCTCT-3; TAp73rev, 5- GCAGATTGAACTGGGCCATGA-3; ÃŽÂ ²2Mfwd, 5-AGCTGTGCTCGCGCTACTCTC-3; ÃŽÂ ²2Mrev, 5-CACACGGCAGGCATACTCATC-3; PUMA fwd PUMArev NOXAfwd NOXArev. The conditions for all QRT-PCR reactions were as follows: 3 minutes at 94 °C followed by 40 seconds at 94 °C, 40 seconds at 60 °C, and 25 seconds at 72 °C for 40 cycles. All PCR products were confirmed by the presence of a single peak upon melting curve analysis and by gel electrophoresis. No-template (water) reaction mixtures and no-RT mixtures were performed on all samples as negative controls. All experiments were performed in duplicate. Protein isolation and Western blot analysis Protein lysates from cells were extracted in ice-cold lysis buffer (0.75% NP-40, 1 mM DTT, and protease inhibitors in PBS). Total protein (25 ÃŽÂ ¼g) was subjected to SDS-PAGE followed by immunoblotting with the following antibodies: p73 (diluted 1:1,000, Ab-2; CalBiochem); pS6K (diluted 1:1,000; Cell Signaling Technology); S6K (diluted 1:1,000, Ab9645; Abcam); and ÃŽÂ ²-tubulin (diluted 1:2,500, D-10; Santa Cruz Biotechnology). Lentiviral production and infection The shRNA lentiviral constructs were created by transferring the U6 promoter-shRNA cassette into a lentiviral backbone, and high-titre lentiviral stocks were generated by co-transfection with packaging vectors into 293T cells as described previously [3, 4, 13]. The shRNA target sequences for TAp73 was 5-GGATTCCAGCATGGACGTCTT-3. The TAp73 targeted sequence is found within p73 exon 3. Therefore, this shRNA does not target ΆNp73 [4]. RESULTS Selective sensitivity of basal-like breast cancer toward cisplatin To gain an overview of the selectivity of chemotherapeutic agents for basal-like breast cancer cells, we compared their antiproliferative properties in a panel of basal-like and luminal-like breast cancer cell lines which has been validated previously through gene profiling [15]. All cells were treated with increasing concentrations of cisplatin, paclitaxel or doxorubicin for 72 hours and growth measured using the MTT assay. Figure 1A and B summarizes the results from these breast cancer cell lines in which basal-like breast cancer cells demonstrated selective sensitivity to cisplatin. This selectivity was absence in cells treated with paclitaxel or doxorubicin suggesting that basal-like breast cancer cells confer selective sensitivity towards cisplatin (Figure 1A, B and Supplement Table 1). Small chemical library screening identify rapamycin as synergistic agents for cisplatin Although cisplatin is currently one of the most used agents in the treatment of cancer, the use of cisplatin is hampered by its side effects, especially neurotoxicity, nephrotoxicity and rug resistance [16]. Hence, the present study was aimed to identify chemosensitizers that could synergize the effects of cisplatin for treatment of basal-like breast cancers. To identify small molecules that enhance sensitivity of basal-like breast cancer cells to cisplatin, a cell-based high-throughput screen was performed using MDA-MB-468 cell line and a small chemical library consisting of 160 well validated specific inhibitors. The screens were done in 96-well plates to which compounds were added at 10  µM, followed by cisplatin at 1  µM. Cell viability was measured 72 hours later by MTT assay. Each plate included controls of untreated cells, cells treated with compounds or cisplatin only, and cells treated with a combination of both agents. Combinations of the treatments that induced growth inhibition higher than those of the same doses used alone (p The molecules identified in this screen includes rapamycin, [3-(Pyridin-2-yl)-4-(4-quinonyl)]-1H-pyrazole (LY364947), 4-(3-Chloroanilino)-6,7-dimethoxyquinazoline (AG1478), (E)3-[(4-Methylphenyl)sulfonyl]-2-propenenitrile (BAY11-7082), 2-(4-Morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) and 4-(4-Fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580). Structures of these compounds and their growth inhibitory effects were shown in Figure 2. The molecular target of these compounds was listed in Table 1. The 6 compounds identified are specific inhibitors of the mTOR, TGF-à ¯Ã‚ Ã‚ ¢, EGFR, NFà ¯Ã‚ Ã‚ «B PI3K/AKT and MAPK pathways which have been previously reported to be upregulated specifically in basal-like breast cancers [7, 17-20]. However, when tested for synergism with cisplatin at fixed concentration ratio, only rapamycin showed synergism when combined with cisplatin in MDA-MB-468 cells using the isobologram method that simulate the median-dose combination index (CI) [14]. The mean combination index at ED50, ED75, and ED90 of rapamycin (10:1 cisplatin:rapamycin) when combined with cisplatin was 0.52 à ¯Ã¢â‚¬Å¡Ã‚ ± 0.06, where combination index Specific synergistic effects of rapamycin and cisplatin in basal-like breast cancer cells Next, we sought to investigate if combination of cisplatin with rapamycin exhibit specific synergism in basal-like breast cancers by comparing their effects in a panel of breast cancer cell lines. The antiproliferative effect of treatment was evaluated using MTT assays and drug interaction was assessed by the isobologram method as described in the previous section. The results demonstrated that combination of rapamysin and cisplatin exhibited selective synergistic effects only in the basal-like MDA-MB-468, MDA-MB-231 and HCC1937 cells, but not in the luminal-like T47D or MCF-7 cells (Figure 3A and Table 2). To ensure that the lack of synergistic effects of rapamycin and cisplatin observed in luminal-like cells is not due the general lack of sensitivity of luminal-like cells to cisplatin per se, we compared the apoptotic effects of cisplatin and rapamycin alone or in combination in MDA-MB-231 and T47D cells using an equal potent dose of cisplatin (IC50 dose). Both cell lines exhibited similar amount of apoptosis following treatment with their respective IC50 dose of cisplatin. Interestingly, when both cell lines were treated with combination of cisplatin and rapamycin, synergistic effects were evidenced only in MDA-MB-231 cells but not in T47D cells. The potentiation effects of rapamycin observed in MDA-MB-231 cells were further enhanced by sequential treatment with rapamycin for 6 hours followed by cisplatin (data not shown). These results demonstrated that rapamycin is capable of sensitizing basal-like breast cancer cells to cisplatin, suggesting that the synergistic effects of rapamyc in and cisplatin may be mediated through a common pathway. Rapamycin sensitizes basal-like cells to cisplatin through p73 up regulation Previous study has shown that inhibition of mTOR by rapamycin up regulate p73 in breast cancer cells [21]. We and others have also demonstrated that p73 is overexpressed in a subset of triple-negative breast tumors and that p73 is required for cisplatin sensitivity in basal-like breast cancer cells [4]. On the basis of these findings, we ask if the synergistic effects of rapamycin and cisplatin combination could be explained by the activation of the p73 pathway. To test this notion, MDA-MB-231 cells were treated with 10  µM of cisplatin and 100 nM rapamycin alone or in combination for 48 hours. mTOR inhibition was confirmed using phospho-S6K as a marker of mTOR activity. Quantitation of the mRNA and protein expression of the TAp73 was performed using qPCR and immunoblotting, respectively. The results showed that treatment of rapamycin or cisplatin alone did not change the expression of TAp73 mRNA but induced significant up regulation of TAp73 protein expression in MDA-MB-231 cells (Figure 4A and B). Next, we evaluated the expression of the two potent pro-apoptotic BH3 only proteins, PUMA and NOXA, which has been identified as specific p73 target genes, using qPCR [22, 23]. As expected, treatment of cells with cisplatin for 48 hours induced mRNA expression of PUMA and NOXA in both MDA-MB-231 and MDA-MB-468 cells. Significant induction of PUMA and NOXA were also observed in MDA-MB-231 cells but not in MDA-MB-468 cells following treatment with rapamycin alone. When cells were treated with combination of cisplatin and rapamycin, the expression of PUMA and NOXA was further enhanced, corroborated with the massive induction of apoptosis as shown in Figure 3B. Together, these results suggest that rapamycin synergize cisplatin activity in basal-like cells through induction of p73 pathway. p73 is required for the synergistic effects of rapamycin and cisplatin in basal-like breast cancer cells To further evaluate whether p73 is the effector of the synergistic effects of rapamycin and cisplatin in basal-like breast cancer cells, we generated a series of isogenic cell lines that have been depleted for TAp73 by stably expressing a shRNA species that target specifically human TAp73. Unlike MDA-MB-231 cells which express one predominant TAp73 isoform (TAp73à ¯Ã‚ Ã‚ ¢) isoform, MDA-MB-468 cells express high levels of two p73 isoforms, TAp73à ¯Ã‚ Ã‚ ¡ and TAp73à ¯Ã‚ Ã‚ ¢ [21]. Figure 5A showed efficient knock-down of TAp73 isoforms in MDA-MB-231 and MDA-MB-468 cells. As expected, treatment of cisplatin alone induced significant amount of apoptosis in MDA-MB-468 vector control cells. This apoptotic effects were further enhanced in the presence of rapamycin, consistent with our previous observations (Figure 3B). In stark contrast, depletion of TAp73 not only reduced the amount of apoptosis following treatment of cisplatin alone but also completely abrogated the synergistic effects of rapamycin (Figure). This result is further supported by the isobologram analysis which showed a lack of synergism of rapamycin-cisplatin treatment in the TAp73 depleted cells. Together, these results suggest that TAp73 is required for the synergistic effects of rapamycin and cisplatin in basal-like breast cancers. DISCUSSION By gene profiling, breast cancers can be classified into 5 molecularly distinct subtypes: luminal A, luminal B, HER2+, basal-like and normal breast cancers. The basal-like subtype, which represents 15-20% of breast cancers, has been subjected to extensive investigation in recent years due to its association with poor patient survival [1, 2, 20, 24]. Unlike many breast cancers, patients diagnosed with basal-like breast cancers are not eligible for molecular targeted therapy that target ER (e.g. tamoxifen, aromatase inhibitors) or HER2 (e.g. Herceptin) as they do not express the estrogen receptor (ER) or progesterone receptor (PR), nor do they have amplified HER2 [1, 24]. The treatment option therefore is relied on aggressive conventional chemotherapies which have limited efficacy, many side effects and often high rate of relapse. Hence, development of an effective therapeutic strategy remains an important goal in the management of basal-like breast cancer. Several lines of evidence has suggested a link between basal-like breast cancers and BRCA1 deficiency [7, 25, 26]. In most cases, the clinical features and outcomes for women with sporadic basal-like breast cancers are broadly similar to those with BRCA1-related cancers including high tendency of developing high grade, high mitotic index tumors, shorter time of relapse, similar pattern of metastatic spread and cytogenetic changes associated with frequent loss of X-chromosome inactivation [7, 27-32]. The majority of BRCA1-associated cancers are also triple-negative (ER, PR and HER2 negative), express basal cytokeratins and other markers commonly seen in basal-like breast cancers (e.g. p53, P-cadherin and EGFR) [7]. Gene expression profiling also demonstrated that BRCA1-associated cancers segregate strongly with basal-like breast cancers [2, 29, 33, 34]. Although BRCA1 somatic gene mutations are uncommon in sporadic basal-like cancers, these tumors have been shown to have a dysfunction al BRCA1 pathway due to BRCA1 gene promoter methylation and/or BRCA1 pathway transcriptional inactivation [7, 25, 26]. The fundamental biological similarities between hereditary BRCA1-related breast cancers and basal-like cancers suggest that strategies targeting the dysfunctional BRCA1 pathway may be effective in basal-like breast cancers. There is increasing evidence that the DNA repair defects characteristic of BRCA1 related cancers, especially defective homologous recombination, confer sensitivity to certain systemic agents, such as platinum-based chemotherapy and poly(ADP-ribose) polymerase (PARP) inhibitors [34-38]. Indeed, recent clinical studies revealed that sporadic basal-like cancers responded to platinum-based chemotherapy and were associated with a high rate of complete pathologic response [9, 11, 38]. Consistent with the clinical data, our in vitro study also reveals that basal-like breast cancer cells confer specific sensitivity to cisplatin as compared to other chemotherapeutic agents (e.g. doxorubicin or paclitaxel) (Figure 1), further support research into the utility of platinum-ba sed agents in basal-like breast cancers. Given the high specificity and response rate of basal-like breast cancers toward platinum-based therapy, our focus is to maximize the benefits associated with this therapy through drug combination strategies. Using a small chemical library consisted of 160 well-validated and specific inhibitors that target the human kinome, we have identified 6 compounds that significantly potentiate the antiproliferative effects of cisplatin in basal-like breast cancer cells. These compounds include rapamycin, LY364947, AG1478, BAY11-7082, LY294002 and SB203580 which targets the mTOR, TGFà ¯Ã‚ Ã‚ ¢RI, NFà ¯Ã‚ Ã‚ «B, PI3K/AKT and MAPK pathway respectively. Of note, these pathways have been reported previously to be over activated in basal-like breast cancers [7, 17, 18, 20]. To further investigate the mode of interaction between these compounds and cisplatin, we performed a drug combination study using the isobologram approach as described previously (Ref). Out of the 6 compounds identified, rapamycin showed the strongest synergistic effects with cisplatin while others (LY364947, AG 1478, BAY11-7082, LY294002 and SB203580) showed mainly additive effects. This result is consistent with other studies which show that inhibition of mTOR by RNAi or small molecules (e.g. rapamycin, CCI-779, RAD001) enhances cisplatin chemosensitivity in ovarian [39-41], endometrial [42], head and neck [43, 44], lung [45], skin [46, 47] and liver [48] cancers. We next compared the synergistic effects of rapamycin in combination with cisplatin in a panel of luminal-like and basal-like breast cancer cell lines that has been previously validated by gene profiling [15]. Intriguingly, the synergistic effects were observed only in MDA-MB-468, MDA-MB-231 and HCC1937 basal-like cells, but not in MCF-7 or T47D luminal-like cells. Several models have been proposed to explain the synergistic effects of rapamycin and cisplatin in cancer cells. Beuvnk et al., 2005 showed that RAD001 (Everolimus), a rapamycin derivative, dramatically enhances cisplatin-induced apoptosis in wild-type p53 but not mutant p53 tumor cells by inhibiting p53-induced p21 expression [49]. Wangpaichitr et al., 2008 demonstrated that inhibition of mTOR by CCI-779 decreased levels of the anti-apoptotic proteins, BCL2/BCLxL, and increasing apoptosis in lung cancer cells that is resistance to cisplatin [50]. Although these models provide important evidence for mTOR inhibition and cisplatin synergism in cancer cells, it fails to explain the specific synergism we observed in basal-like breast cancer cells, as the basal-like cells that we tested are p53 mutated and do not express high level of BCL2/BCLxL (data not shown). This led us to postulate that a common signal transduction pathway inhibited by rapamycin may be an important component that sy nergizes cisplatin sensitivity in basal-like cells. Since p73 has been reported to mediate cisplatin sensitivity in a subset of triple-negative breast cancer cells [4] and that inhibition of mTOR by rapamycin or RNAi lead to upregulation of p73 [21], we postulated that activation of the p73 pathways might be important for the synergistic effects of rapamycin. To test the role of p73 in rapamycin and cisplatin synergism, we first evaluated the expression of p73 mRNA and protein levels following treatment with cisplatin or rapamycin alone or in combination in MDA-MB-231 cells. Consistent with previous studies, treatment of cells with cisplatin or rapamycin alone induces p73 protein expression followed by transcriptional activation of the 2 potent pro-apoptotic p73 target genes, PUMA and NOXA. When MDA-MB-231 cells were co-treated with rapamycin and cisplatin, the elevation of p73 and its pro-apoptotic target genes were synergistically enhanced. The observed changes in p73 protein in MDA-MB-231 cells, however, were not due to parallel changes in p73 RNA levels, suggesting that inhibition of mTOR might lead to inactivation of a yet unknown p73 specific protein degradation pathway. To validate that the rapamycin and cisplatin synergism is mediated by p73, we generated isogenic MDA-MB-231 and MDA-MB-468 cells that were depleted for p73 using a lentiviral-shRNA that target specifically the transactivating isoform of p73 (TAp73). Indeed, depletion of TAp73 in MDA-MB-231 and MDA-MB-468 cells completely abrogated the synergistic effects of rapamycin suggesting that the synergism between rapamycin and cisplatin required p73 function. Although the combination of cisplatin and rapamycin has not been previously investigated in clinical study, it is worth noting that a phase II neo-adjuvant clinical trial of cisplatin and RAD001 (Everolimus), in patients with triple-negative breast cancers has recently open for recruitment (ClinicalTrials.gov Identifier: NCT00930930), and will be able to address the potential of cisplatin and mTOR inhibitors combination therapy directly. It would be equally intriguing to determine the role of p73 related pathway as potential biomarkers that might predict response to treatment given the pivotal role of p73 in the synergistic effects of mTOR inhibition and cisplatin sensitivity. In conclusion, combination of mTOR inhibitors and cisplatin may be a useful therapeutic strategy in basal-like breast cancers.

Effect of Concentration on Osmosis Essay -- GCSE Biology Osmosis Cours

Effect of Concentration on Osmosis Aim To find out how the concentration of sucrose solution affects the mass of the potato chip left in the solution for one day. Prediction I predict that when the sucrose concentration is low the potato chip will gain mass. This is because there will be a higher sucrose concentration in the potato chip so water will go into the potato from the solution. I predict that when there is a high concentration of sucrose the potato will lose mass. This is because there is a higher concentration of sucrose solution in the solution compared to that in the potato chip so water from the potato will go into the solution to even it out. Osmosis is "the movement of a solvent through a selectively permeable membrane (as of a living cell) into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane" Osmosis is the movement of water from high water concentration to lower water concentration through a selectively permeable membrane. Selectively permeable membranesare very thin layers of material (cell membranes are selectively-permeable), which allow some molecules to pass through them but prevent other molecules from passing through. Cell membranes will allow small molecules like Oxygen, water, Carbon Dioxide, Ammonia, Glucose, amino-acids, etc. to pass through. Cell membranes will not allow larger molecules like Sucrose, Starch, protein, etc. to pass through. In my experiment I will have a test tube with a potato chip in. The outside wall of the potato chip is selectively permeable so it lets water pass through it but not bigger molecules such as sucrose. In the test tubes I will put different concentrations of sucrose solution. When the concentration of the solution is lower than that in the potato, water will pass through the selectively permeable wall into the potato. Potato cells Sucrose solution The mass of the potato chip increases Sucrose molecule Water molecule When the sucrose solution is stronger outside if the potato chip water will move out from the potato chip into the solution. When the concentration is the same on both sides of the selectively permeable wall nothing passes through it and the mass will stay the same. Plan Apparatus Five test tubes Labels Ruler Scales Tissue... ...hips in each test tube. This would make it more accurate as when I had two in a test tube if one of them was a long way out it made the graph not follow the line well when I plotted the averages. There was one anomalous result at 0.5 mol. I think this was because we patted them dry when we got them out of the test tubes as we did not want to weigh there water on the outside of the potato but I think that we may not have dried them all equally so this anomalous result may have been due to it having water left on the outside of it. Also the potato itself was not from the same part of the potato and was not exactly the same size, although I did try to cut them to 36mm each. I could also try the same experiment but with different volumes of cell tissues and see if the percentage change differed with a bigger and smaller surface area. I could now investigate the smaller range near to 0.25 to see the sucrose concentration equivalent to the potato. Finally, I could extend the experiment to a more exact level by looking at the potato cylinders under a microscope, then I would be able to see the cells in greater detail and draw some more observational results.

Biblical Allusions Throughout of Mice and Men Essay

â€Å"He calls Of Mice and Men a parable that illustrates the biblical conflict between the brothers Cain and Abel† (Goldhurst 48). Therefore the people who have read the story Of Mice and Men can automatically see the resemblance between the two stories. Of Mice and Men is a novelette by John Steinbeck, it is about two men who are migratory workers that works on farms. Of Mice and Men contains many Biblical allusions including the Story of Cain and Abel, the longing for Eden, and facing temptation. In Of Mice and Men and the Old Testament the themes are similar. It is stated in the â€Å"A Parable Curse of Cain.† â€Å"Of Mice and Men is a story about the nature of man’s fate in a fallen world, with particular emphasis upon the question: is man destined to live alone, a solitary wanderer on the face of the earth, or is it the fate of man to care for man, to go his way in companionship with another? This is the same theme that occurs in The Old Testament† (Goldhurst 49). This proves that Of Mice and Men and The Old Testament have a similar theme. One reoccurring theme in Of Mice and Men and The Old Testament is loneliness will always follow man and innocence keeps ideas alive. The curse that the Lord placed upon Cain was that agricultural labor was going to be difficult, and he will be lonely while being a fugitive (Genesis 4:12). In Of Mice and Men George and Lennie are fugitives that are migratory workers but George at times feels lonely even though he has Lennie because he doesn’t have a romantic partner. This shows how these two stories are similar within their themes. Worked Cited Goldhurst, William. â€Å"A Parable of the Curse of Cain.† Readings on John Steinbeck- Of Mice and Men. Ed. Jill Karson, Bruno Leone, Brenda Salcup, and Brenda Szumski. San Diego, CA: Greenhaven Press, 1998. 48-58. Print The New Oxford Annotated Bible. Ed. Bruce M. Metzger, Roland E. Murphy, and Bernhard W. Anderson. New York: Oxford University Press, 1994. 2-7. Print. Owens, Luis. â€Å"Of Mice and Men: The Dream of Commitment.† Modern Critical View John Steinbeck. Ed. Harold Bloom. New York: Chelsea House, 1987. 145-149. Print.

Percent Composition by Mass Example Problem

Percent composition by mass is a statement of the percent mass of each element in a chemical compound or the percent mass of components of a solution or alloy. This worked example chemistry problem works through the steps to calculate percent composition by mass. The example is for a sugar cube dissolved in a cup of water. Percent Composition by Mass Question A 4 g sugar cube (Sucrose: C12H22O11) is dissolved in a 350 ml teacup of 80 Â °C water. What is the percent composition by mass of the sugar solution? Given: Density of water at 80 Â °C 0.975 g/ml Percent Composition Definition Percent Composition by Mass is the mass of the solute divided by the mass of the solution (mass of the solute plus mass of the solvent), multiplied by 100. How to Solve the Problem Step 1 - Determine mass of solute We were given the mass of the solute in the problem. The solute is the sugar cube. masssolute 4 g of C12H22O11 Step 2 - Determine mass of solvent The solvent is the 80 Â °C water. Use the density of the water to find the mass. density mass/volume mass density x volume mass 0.975 g/ml x 350 ml masssolvent 341.25 g Step 3 - Determine the total mass of the solution msolution msolute msolvent msolution 4 g 341.25 g msolution 345.25 g Step 4 - Determine percent composition by mass of the sugar solution. percent composition (msolute / msolution) x 100 percent composition ( 4 g / 345.25 g) x 100 percent composition ( 0.0116) x 100 percent composition 1.16% Answer: The percent composition by mass of the sugar solution is 1.16% Tips for Success Its important to remember you use the total mass of the solution and not just the mass of the solvent. For dilute solutions, this doesnt make a huge difference, but for concentrated solutions, youll get a wrong answer.If youre given the mass of solute and mass of solvent, life is easy, but if youre working with volumes, youll need to use density to find the mass. Remember density varies according to temperature. Its unlikely youll find a density value corresponding to your exact temperature, so expect this calculation to introduce a small amount of error into your calculation.