Molecular changes to HeLa cells on continuous exposure to cisplatin or paclitaxel

CUL4A silencing attenuates cervical carcinogenesis and improves Cisplatin sensitivity

CUL4A is an ubiquitin ligase deregulated in numerous pathologies including cancer and even hijacked by viruses for facilitating their survival and propagation. However, its role in Human papilloma virus (HPV)-mediated cervical carcinogenesis remains elusive. The UALCAN and GEPIA datasets were analyzed to ascertain the transcript levels of CUL4A in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) patients. Subsequently, various biochemical assays were employed to explore the functional contribution of CUL4A in cervical carcinogenesis and to shed some light on its involvement in Cisplatin resistance in cervical cancer. Our UALCAN and GEPIA datasets analyses reveal elevated CUL4A transcript levels in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) patients that correlate with adverse clinicopathological parameters such as tumor stage and lymph node metastasis. Kaplan-Meier plot and GEPIA assessment depict poor prognosis of CESC patients having high CUL4A expression. Varied biochemical assays illustrate that CUL4A inhibition severely curtails hallmark malignant properties such as cellular proliferation, migration, and invasion of cervical cancer cells. We also show that CUL4A knockdown in HeLa cells causes increased susceptibility and better apoptotic induction toward Cisplatin, a mainstay drug used in cervical cancer treatment. More interestingly, we find reversion of Cisplatin-resistant phenotype of HeLa cells and an augmented cytotoxicity towards the platinum compound upon CUL4A downregulation. Taken together, our study underscores CUL4A as a cervical cancer oncogene and illustrates its potential as a prognosis indicator. Our investigation provides a novel avenue in improving current anti-cervical cancer therapy and overcoming the bottle-neck of Cisplatin resistance.

Cellular landscaping of cisplatin resistance in cervical cancer

Cervical cancer (CC) caused by human papillomavirus (HPV) is one of the largest causes of malignancies in women worldwide. Cisplatin is one of the widely used drugs for the treatment of CC is rendered ineffective owing to drug resistance. This review highlights the cause of resistance and the mechanism of cisplatin resistance cells in CC to develop therapeutic ventures and strategies that could be utilized to overcome the aforementioned issue. These strategies would include the application of nanocarries, miRNA, CRIPSR/Cas system, and chemotherapeutics in synergy with cisplatin to not only overcome the issues of drug resistance but also enhance its anti-cancer efficiency. Moreover, we have also discussed the signaling network of cisplatin resistance cells in CC that would provide insights to develop therapeutic target sites and inhibitors. Furthermore, we have discussed the role of CC metabolism on cisplatin resistance cells and the physical and biological factors affecting the tumor microenvironments.

Synthesis, characterization, and biological studies of some biometal complexes

Background

Metal complexes Cu[C13H8O4N]22, Ni[Cl3H8O4N]23, and Co[C13H8O4N]24 of bioinorganic relevance have been synthesized with the Schiff base ligand 2-furylglyoxal–anthranilic acid (FGAA) [C13H9O4N] 1.

All the complexes are well characterized by various spectral and physical methods. The antimicrobial activity of the complexes has been studied against some of the pathogenic bacteria and fungi.

Results

Results indicate that complexes have higher antimicrobial activity than the free ligand. This would suggest that chelation reduces considerably the polarity of the metal ions in the complexes which in turn increases the hydrophobic character of the chelate and thus enables permeation, through the lipid layer of microorganisms. All the complexes were assessed for their anticancer studies against a panel of selected cancer cells HOP62 and BT474 respectively. Results showed that the complexes are promising chemotherapeutic alternatives in the search of anticancer agents. The fluorescence quenching phenomenon is observed in the Schiff base metal complexes.

Conclusion

The octahedral transition metal complexes 2, 3, and 4 have been obtained by treatment of ligand 2-furylglyoxal-anthranilic acid (FGAA) 1 with metal acetate. Complexes under investigations have shown antimicrobial, potential anticancer, and the DNA binding studies.

Graphical abstract

Theranostic combinatorial drug-loaded coated cubosomes for enhanced targeting and efficacy against cancer cells

Cubosomes, a product of nanobioengineering, are self-structured lipid nanoparticles that act like drug-loaded theranostic probes. Here, we describe a simple method for the preparation of combinatorial drug-loaded cubosomes with, proof-of-principle, therapeutic effect against cancer cells, along with diagnostic capabilities. Anticancer drugs cisplatin and paclitaxel were loaded in the cubosomes in combination. The cubosomes were coated with a layer of poly-Ɛ-lysine, which helped avoid the initial burst release of drug and allowed for a slow and sustained release for better efficacy. Cubosomes were imaged by transmission electron microscope, and their dispersion analyzed in vitro by differential scanning calorimetric and X-ray diffractogram studies. The microscopic images depicted spherical polyangular structures, which are easily distinguishable. The analyses revealed that the drug is uniformly dispersed all through the cubosomes. Further characterization was carried out by zeta-potential measurement, in vitro release, and entrapment efficiency studies. The in vitro studies established that the coating of cubosomes successfully reduced the burst release of drugs initially and confirmed a slow, sustained release over increased time. Comparative cytotoxicity of coated, uncoated, and blank cubosomes was evaluated, using human hepatoma HepG2 cell line, and the formulations were found to be entirely nontoxic, similar to the blank ones. The therapeutic efficiency of the cubosomes against HeLa cells was confirmed by the impedance measurement and fluorescent imaging. Furthermore, the reduction in impedance in cells treated with coated combinatorial cubosomes proved the impairment of HeLa cells, as confirmed by fluorescence microscopy.

Integrating a generalized data analysis workflow with the Single-probe mass spectrometry experiment for single cell metabolomics

We conducted single cell metabolomics studies of live cancer cells through online single cell mass spectrometry (SCMS) experiments combined with a generalized comprehensive data analysis workflow. The SCMS experiments were carried out using the Single-probe device coupled with a mass spectrometer to measure molecular profiles of cells in response to two mitotic inhibitors, taxol and vinblastine, under a series of treatment conditions. SCMS metabolomic data were analyzed using a comprehensive approach, including data pre-treatment, visualization, statistical analysis, machine learning, and pathway enrichment analysis. For comparative studies, traditional liquid chromatography-MS (LC-MS) experiments were conducted using lysates prepared from bulk cell samples. Metabolomic profiles of single cells were visualized through Partial Least Square-Discriminant Analysis (PLS-DA), and the phenotypic biomarkers associated with emerging phenotypes induced by drug treatment were discovered and compared through a series of rigorous statistical analysis. Species of interest were further identified at both the single cell and population levels. In addition, four biological pathways potentially involved in the drug treatment were determined through pathway enrichment analysis. Our work demonstrated the capability of comprehensive pipeline studies of single cell metabolomics. This method can be potentially applied to broader types of SCMS datasets for future pharmaceutical and chemotherapeutic research.

Synthesis, cytotoxic activity and drug combination study of tertiary amine derivatives of 2′,4′-dihydroxyl-6′-methoxyl-3′,5′-dimethylchalcone

Tertiary amine derivative of DMC (2b) exhibited broad spectrum of cytotoxicity and strong synergism with Taxol® against HeLa/Tax cells.

Molecular mechanisms of cisplatin resistance in cervical cancer

Patients with advanced or recurrent cervical cancer have poor prognosis, and their 1-year survival is only 10%–20%. Chemotherapy is considered as the standard treatment for patients with advanced or recurrent cervical cancer, and cisplatin appears to treat the disease effectively. However, resistance to cisplatin may develop, thus substantially compromising the efficacy of cisplatin to treat advanced or recurrent cervical cancer. In this article, we systematically review the recent literature and summarize the recent advances in our understanding of the molecular mechanisms underlying cisplatin resistance in cervical cancer.

Expression of aryl hydrocarbon receptor nuclear translocator enhances cisplatin resistance by upregulating MDR1 expression in cancer cells

The identification of molecular pathways in cancer cells is important for understanding the cells' underlying biology and for designing effective cancer therapies. We demonstrate that the expression of aryl hydrocarbon receptor nuclear translocator (ARNT) is critical during the development of cisplatin resistance. The reduced expression of ARNT was correlated with cisplatin-induced cell death in drug-sensitive cells. In addition, suppression of ARNT reversed the characteristics of cisplatin-resistant cells, making these cells cisplatin-sensitive, and significantly enhanced caspase-3 activation, DNA fragmentation, and apoptosis. The inhibition of colony formation, regulated by cisplatin, was more significant in ARNT-knockdown cells than in parental cells. In a xenograft analysis of severe combined immunodeficiency mice, cisplatin also efficiently inhibited ARNT-deficient c4 tumors but not ARNT-containing vT2 tumor formation. Furthermore, the downregulation of multidrug resistance 1 (MDR1) expression and retention of drugs in cells caused by suppression of ARNT, resulting in the resensitization of drug-resistant cells to cisplatin, was observed. When overexpressed, ARNT interacted with Sp1 to enhance the expression of MDR1 through Sp1-binding sites on the MDR1 promoter, resulting in a reversal of the effect of cisplatin on cell death. In addition, ARNT-induced MDR1 expression was inhibited in Sp1-knockdown cells. These results reveal previously unrecognized, multifaceted functions of ARNT in establishing the drug-resistant properties of cancer cells by the upregulation of MDR1, highlighting ARNT's potential as a therapeutic target in an important subset of cancers.

Off-the-shelf microsponge arrays for facile and efficient construction of miniaturized 3D cellular microenvironments for versatile cell-based assays

The integration of microfabrication and biomaterials enables construction of miniaturized 3D microenvironments with biomimetic micro-architectural and functional features to advance cell-based assays for mechanism investigation of physio/pathology and for prediction of drug responses. However, current biomaterials-assisted constructions of miniaturized 3D cellular microenvironments usually involve cells in the microfabrication process, limiting their wide application in most biomedical labs, where expertise and facilities are not readily available. Here we tackle this challenge by developing off-the-shelf microsponge arrays as pre-formed micro-patterned templates which can separate the microfabrication steps from the cell-handling steps and miniaturize the cell-based assays. The microsponge arrays with tailored microarchitectures (e.g. micropillar/well arrays or bifurcated vascular network) could be stored and delivered to distant locations as ready-to-use chips. The highly porous and microscale sponges enabled automatic and uniform loading of cellular niche components (cells, matrices and soluble factors) by simply pipetting, making it accessible to any lab with basic cell culture setups. Meanwhile, the chips containing miniaturized 3D cellular microenvironments with versatile micro-architectural designs could be integrated (i.e. by autoloading and sandwiching) to enable novel 3D cell-based assays (e.g. discrete gradient-based cytotoxicity test and horizontal 3D invasion assay) in an efficient and parallel manner. The off-the-shelf platform based on microsponge array is expected to be widely applicable across multiple disciplines in cell biology, cell/tissue engineering and pharmacological science.

Factors affecting the sensitivity of human-derived esophageal carcinoma cell lines to 5-fluorouracil and cisplatin

Effective chemotherapy against esophageal carcinoma is considered achievable with a combination of 5-fluorouracil (5-FU) and cisplatin (CDDP). However, chemo-therapy remains ineffective in certain patients. The aim of this study was to clarify the factors which affect sensitivity to 5-FU and CDDP. The effects of factors known to influence sensitivity to 5-FU and CDDP, namely transporters, DNA repair enzymes and metabolic enzymes, were examined. mRNA levels of four transporters, SLC22A2, SLC23A2, ABCB1 and ABCC2, two DNA repair-related enzymes, Rad51 and MSH2, and one metabolic enzyme, dihydropyrimidine dehydrogenase (DPYD), showed a strong correlation (|r|>0.7) with IC₅₀ values for 5-FU. In addition, the mRNA levels of ABCC2, MSH2 and DPYD showed a strong correlation (|r|>0.7) with the IC₅₀ values for CDDP. Gimeracil, a DPYD inhibitor, enhanced the sensitivity of some cells to 5-FU but decreased the sensitivity of all the cells to CDDP. The inhibitory effects of ABCC2 with MK571 did not correspond to those observed in the correlation analysis. In conclusion, mRNA levels of SLC22A2, SLC23A2, ABCB1, ABCC2, Rad51, MSH2 and DPYD were confirmed to be strongly correlated with IC50 values for 5-FU, and mRNA levels of ABCC2, MSH2 and DPYD were confirmed to be strongly correlated with IC₅₀ values for CDDP. In addition, the inhibition of DPYD appeared to affect the cytotoxicity of CDDP.

Optical molecular imaging approach for rapid assessment of response of individual cancer cells to chemotherapy

Predicting the response of individual patients to cytotoxic chemotherapy drugs is critical for developing individualized therapies. With this motivation, an optical molecular imaging approach was developed to detect cisplatin induced changes in the uptake and intracellular retention of choline. Intracellular uptake of choline was characterized using a click chemistry reaction between propargyl choline and Alexa-488 azide. Cisplatin induced changes in the uptake of propargyl choline in cells and tumor spheroids were compared with similar measurements using a fluorescent analogue of deoxyglucose and conventional cell viability assays. Uptake and intracellular retention of propargyl choline decreased with an increase in concentration of cisplatin. Intracellular uptake of propargyl choline was significantly reduced within 3 h of incubation with a sub-lethal dose of cisplatin. Results demonstrate that the imaging approach based on propargyl choline was more sensitive in detecting the early response of cancer cells to cisplatin as compared to the imaging based on fluorescent analogue of deoxyglucose and cell viability assays. Imaging measurements in tumor spheroids show a significant decrease in the uptake of propargyl choline following treatment with cisplatin. Overall, the results demonstrate a novel optical molecular imaging approach for rapid measurement of the response of individual cancer cells to cisplatin treatment.

Pro-inflammatory cytokines interleukin-1 beta, interleukin 6, and tumor necrosis factor-alpha alter the expression and function of ABCG2 in cervix and gastric cancer cells

The ATP-binding cassette sub-family G member 2 (ABCG2) is implicated as a member of multidrug resistant proteins in tumors, mediating efflux of a wide spectrum of anticancer drugs. Pro-inflammatory cytokines, which are present within the micro-environment of tumors and inflammation, are able to modulate the expressions and activities of different drug transporters. This study was aimed to evaluate the short-term (72-h treatment) effects of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) on the expression and function of ABCG2 in cervix carcinoma and gastric cancer cells. Effects of pro-inflammatory cytokines on mRNA, protein expression, and function of ABCG2 were studied using real time RT-PCR and flow cytometry methods, respectively. HeLa cells treated with IL-1β, IL-6, or TNF-α showed decrements in ABCG2 mRNA levels without any changes in protein expression and function of ABCG2. IL-6 and TNF-α had no effects on mRNA, protein expression, and function of ABCG2 in EPG85-257 cells. Although IL-1β did not alter ABCG2 at mRNA or protein levels in EPG85-257 cells, it augmented function of ABCG2 in these cells. Mitoxantrone accumulation was also amplified in IL-1β-, IL-6- or TNF-α-treated HeLa cells and in IL-1β-treated EPG85-257 cells. In conclusion, pro-inflammatory cytokines were able to modulate the expression of ABCG2 at transcriptional and post-transcriptional levels in human cervix and gastric cancer cells.

Designed antimicrobial and antitumor peptides with high selectivity

We report a new class of cationic amphiphilic peptides with short sequences, G(IIKK)(n)I-NH(2) (n = 1-4), that can kill Gram-positive and Gram-negative bacteria as effectively as several well-known antimicrobial peptides and antibiotics. In addition, some of these peptides possess potent antitumor activities against cancer cell lines. Moreover, their hemolytic activities against human red blood cells (hRBCs) remain remarkably low even at some 10-fold bactericidal minimum inhibitory concentrations (MICs). When bacteria or tumor cells are cocultured with NIH 3T3 fibroblast cells, G(IIKK)(3)I-NH(2) showed fast and strong selectivity against microbial or tumor cells, without any adverse effect on NIH 3T3 cells. The high selectivity and associated features are attributed to two design tactics: the use of Ile residues rather than Leu and the perturbation of the hydrophobic face of the helical structure with the insertion of a positively charged Lys residue. This class of simple peptides hence offers new opportunities in the development of cost-effective and highly selective antimicrobial and antitumor peptide-based treatments.

Up-regulation of breast cancer resistance protein plays a role in HER2-mediated chemoresistance through PI3K/Akt and nuclear factor-kappa B signaling pathways in MCF7 breast cancer cells

Human epidermal growth factor receptor 2 (HER2/neu, also known as ErbB2) overexpression is correlated with the poor prognosis and chemoresistance in cancer. Breast cancer resistance protein (BCRP and ABCG2) is a drug efflux pump responsible for multidrug resistance (MDR) in a variety of cancer cells. HER2 and BCRP are associated with poor treatment response in breast cancer patients, although the relationship between HER2 and BCRP expression is not clear. Here, we showed that transfection of HER2 into MCF7 breast cancer cells (MCF7/HER2) resulted in an up-regulation of BCRP via the phosphatidylinositol 3-kinase (PI3K)/Akt and nuclear factor-kappa B (NF-κB) signaling. Treatment of MCF/HER2 cells with the PI3K inhibitor LY294002, the IκB phosphorylation inhibitor Bay11-7082, and the dominant negative mutant of IκBα inhibited HER2-induced BCRP promoter activity. Furthermore, we found that HER2 overexpression led to an increased resistance of MCF7 cells to multiple antitumor drugs such as paclitaxel (Taxol), cisplatin (DDP), etoposide (VP-16), adriamycin (ADM), mitoxantrone (MX), and 5-fluorouracil (5-FU). Moreover, silencing the expression of BCRP or selectively inhibiting the activity of Akt or NF-κB sensitized the MCF7/HER2 cells to these chemotherapy agents at least in part. Taken together, up-regulation of BCRP through PI3K/AKT/NF-κB signaling pathway played an important role in HER2-mediated chemoresistance of MCF7 cells, and AKT, NF-κB, and BCRP pathways might serve as potential targets for therapeutic intervention.

[Classification of anticancer drugs with different mechanisms based on amino-acid consumption profiling in culture media]

An approach for quantitative determination of amino-acid consumption profiling in culture media by high performance liquid chromatography with fluorescence detection (HPLC-FLD) was developed and validated, using o-phthalic dicarboxaldehyde (OPA) as the derivatizing reagent and norvaline as the internal standard. Mobile phase A was 10 mmol/L Na2HPO4Na2B4O7 buffer (pH 7.95), and mobile phase B was acetonitrile-methanol-water (45:45:10, v/v/v). The linear elution program was 5% B at the start and 52% B at the end in 35 min. The 17 free amino-acids (FAAs) were separated satisfactorily in 33 min. Following HeLa cells incubation in conditioned medias of taxol (4 micromol/L) and mitomycin (75 micromol/L), respectively, with control for 24 h, the media 17 amino-acid consumption profilings were determined, and then analyzed by multivariate statistical analysis based on Matlab7.1 software platform. Relation analysis performed by partial least squares-discriminant analysis (PLS-DA) indicated that in comparison with the control group, the media amino-acid consumption profiling can distinguish the two anticancer drugs with different mechanisms, which provides a new perspective for the pre-classification of drug action mechanisms during the screening of new anticancer drugs. Meanwhile, the idea from the outer into the inner has convenient and economic characteristics.

Quantitative proteomic and interaction network analysis of cisplatin resistance in HeLa cells

Cisplatin along with other platinum based drugs are some of the most widely used chemotherapeutic agents. However drug resistance is a major problem for the successful chemotherapeutic treatment of cancer. Current evidence suggests that drug resistance is a multifactorial problem due to changes in the expression levels and activity of a wide number of proteins. A majority of the studies to date have quantified mRNA levels between drug resistant and drug sensitive cell lines. Unfortunately mRNA levels do not always correlate with protein expression levels due to post-transcriptional changes in protein abundance. Therefore global quantitative proteomics screens are needed to identify the protein targets that are differentially expressed in drug resistant cell lines. Here we employ a quantitative proteomics technique using stable isotope labeling with amino acids in cell culture (SILAC) coupled with mass spectrometry to quantify changes in protein levels between cisplatin resistant (HeLa/CDDP) and sensitive HeLa cells in an unbiased fashion. A total of 856 proteins were identified and quantified, with 374 displaying significantly altered expression levels between the cell lines. Expression level data was then integrated with a network of protein-protein interactions, and biological pathways to obtain a systems level view of proteome changes which occur with cisplatin resistance. Several of these proteins have been previously implicated in resistance towards platinum-based and other drugs, while many represent new potential markers or therapeutic targets.

Activation of p53/p21/PUMA alliance and disruption of PI-3/Akt in multimodal targeting of apoptotic signaling cascades in cervical cancer cells by a pentacyclic triterpenediol from Boswellia serrata

Cervical carcinoma is a growing menace to women health worldwide. This study reports the apoptotic cell death in human cervical cancer HeLa and SiHa cells by a pentacyclic triterpenediol (TPD) from Boswellia serrata by a mechanism different from reported in HL-60 cells. It caused oxidative stress by early generation of nitric oxide and reactive oxygen species that robustly up regulated time-dependent expression of p53/p21/PUMA while conversely abrogating phosphatidylinositol-3-kinase (PI3K)/Akt pathways in parallel. TPD also decreased the expression of PI3K/pAkt, ERK1/2, NF-kappaB/Akt signaling cascades which coordinately contribute to cancer cell survival through these distinct pathways. The tumor suppressor p53 pathway predominantly activated by TPD further up-regulated PUMA, which concomitantly decreased the Bcl-2 level, caused mitochondrial membrane potential loss with attendant translocation of Bax and drp1 to mitochondria and release of pro-apoptotic factors such as cytochrome c and Smac/Diablo to cytosol leading to caspases-3 and -9 activation. In addition both the phospho-p53 and p21 were found to accumulate heavily in the nuclear fraction with attendant decrease in topoisomarase II and survivin levels. On the contrary, TPD did not affect the extrinsic signaling transduction pathway effectively through apical death receptors. Interestingly, N-acetyl cysteine, ascorbate and s-methylisothiourea (sMIT) rescued cells significantly from TPD induced DNA damage and caspases activation. TPD may thus find usefulness in managing and treating cervical cancer.

Arsenic trioxide inhibits the growth of adriamycin resistant osteosarcoma cells through inducing apoptosis

Given that arsenic trioxide (As(2)O(3)) has been successfully used as a chemotherapeutic agent for refractory malignant tumors, this study is aimed at investigating the effect of As(2)O(3) on human Adriamycin resistant osteosarcoma cell line Saos-2. The mechanism underlying multi drug resistance (MDR) in osteosarcoma cells and the anti-tumor effect of As(2)O(3) on Adriamycin resistant osteosarcoma cells were analyzed. In our experiment, we first selected Adriamycin resistant osteosarcoma cell line by growing the classic osteosarcoma cell line Saos-2 in the medium with increasing drug concentrations. Then, we compared the IC50s of the osteosarcoma cells treated with different anticancer drugs by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Subsequently, we assessed the expression of classic MDR related molecules, Pgp, multidrug resistance-associated protein (MRP) and glutathione (GSH) activity in the wild type and Adriamycin resistant Saos-2 cells. Furthermore, the apoptosis was assessed by concerning DNA fragment and flow cytometry with Annexin-V staining. To elucidate the underlying mechanism of the apoptosis, related proteins Bcl-2, Bcl-xL, Bax, Bak, cleaved Caspase-3 and cleaved Caspase-9 were analyzed by western blotting. The data showed that the resistance to Adriamycin affected the sensitivity of osteosarcoma cell to other chemotherapeutic agents. The IC50s of Saos-2/ADM cells for methotrexate (1.74-fold), Cisplatin (1.43-fold) and As(2)O(3) (1.21-fold) were increased compared with Saos-2 control cells. The expression of Pgp was upregulated comparing with the control cells. No significant difference was detected about the MRP and the glutathione-S-transferase activity and intracellular GSH concentration among different treated osteosarcoma cells. Apoptosis was observed and proved. The western blotting showed that the expression of Bcl-2 and Bcl-xL was downregulated. Meanwhile, the level of Bax, Bak, cleaved Caspase-3 and cleaved Caspase-9 was upregulated after treated with As(2)O(3). The study suggests that Adriamycin resistant osteosarcoma cells have good response to As(2)O(3)-based chemotherapy in vitro, probably via the pathway of inducing apoptosis. And As(2)O(3) might serve as an excellent alternative candidate for adjuvant chemotherapeutic agent on this incurable pediatric sarcoma.

Effect of ABCG2 on cytotoxicity of platinum drugs: interference of EGFP

ATP-binding drug efflux transporters decrease intracellular concentrations of cytotoxic drugs, causing multidrug resistance in cancer. In this study, we examined possible interactions of ABCG2 transporter with platinum cytotoxic drugs. We demonstrate here an interference of platinum drugs with enhanced green fluorescence protein (EGFP) in the cellular models, where EGFP was employed as a reporter gene. Cytotoxicity of cisplatin (CIP), carboplatin (CAP) and oxaliplatin (OXP) was significantly lowered in MDCKII cells transfected with ABCG2 transporter and EGFP reporter. The IC(50) values in MDCKII-ABCG2 were 25.7, 164 and 165 microM for CIP, CAP and OXP, respectively, whereas IC(50) for the same cytostatics in MDCKII cells were as follows: 15.4, 133 and 50.3 microM. Addition of fumitremorgin C (FTC), a potent ABCG2 inhibitor, significantly suppressed the resistance of MDCKII-ABCG2 to OXP, suggesting that OXP interacts with ABCG2. However, FTC did not change the sensitivity of the cells to CIP and CAP. We assume that EGFP rather than ABCG2 causes the diminished toxicity of the platinum cytostatics in the transfected cells. This hypothesis was confirmed in human Hep2 cells expressing EGFP: using MTT test, IC(50) of 30.0, 247 and 27.9 microM were obtained for CIP, CAP and OXP, respectively, while 12.3, 106 and 20.5 microM were observed in the parent Hep2 cells. Employing neutral red cytotoxicity assay, similar data were obtained (IC(50) 7.73, 685 and 112 microM for CIP, CAP, and OXP, respectively, in the Hep2-EGFP cells and 1.65, 79.4 and 24.5 microM in the parent Hep2 cells). Caspase-3/7 assay revealed lower susceptibility of EGFP expressing Hep2 cells to apoptosis induced by CIP when compared to the parent cell line. We therefore conclude that EGFP in transfected cells interferes with cytotoxicity of platinum drugs by hindering the drug induced apoptosis and could cause misinterpretation of results obtained in cytotoxicity studies.

Effects of Agaricus blazei Murill extract on sensitivity to chemotherapeutic agents in HeLa cells and its resistant sublines

Agaricus blazei Murill (ABM; Japanese name: Kawahiratake or Agarikusutake) extract is a widely used dietary supplement. However, limited information is available on the effects of the extract on the effectiveness of the chemotherapeutic agents. In this study, we examined the effects of ABM extract (Kyowa Wellness Co., Ltd.) on sensitivity to chemotherapeutic agents, paclitaxel and doxorubicin as MDR1/P-glycoprotein substrates, and cisplatin and 5-fluorouracil as non-substrates, in human cervical carcinoma HeLa cells, and paclitaxel-resistant and cisplatin-resistant derivatives (HeLa/TXL and HeLa/CDDP, respectively). The extract had no growth inhibitory effects on HeLa and the resistant cells at concentrations ranging from 7.6 × 10(-4) μ g/ml to 8.0 × 10(2)μ g/ml, indicating no remarkable cytotoxic activity in vitro. In the presence of 0.1, 0.5, and 1 μ g/ml of ABM extract, sensitivity to paclitaxel, cisplatin and 5-fluorouracil did not change in HeLa, HeLa/TXL and HeLa/CDDP cells. However, the extract reduced sensitivity to doxorubicin in HeLa/TXL and HeLa/CDDP cells in a concentration-dependent manner. In conclusion, the concomitant use of ABM extract minimally affected sensitivity to various chemotherapeutic agents in HeLa cells and resistant sublines in vitro.

A systematic review of platinum and taxane resistance from bench to clinic: An inverse relationship

We undertook a systematic review of the pre-clinical and clinical literature for studies investigating the relationship between platinum and taxane resistance. Medline was searched for (1) cell models of acquired drug resistance reporting platinum and taxane sensitivities and (2) clinical trials of platinum or taxane salvage therapy in ovarian cancer. One hundred and thirty-seven models of acquired drug resistance were identified. 68.1% of cisplatin-resistant cells were sensitive to paclitaxel and 66.7% of paclitaxel-resistant cells were sensitive to cisplatin. A similar inverse pattern was observed for cisplatin vs. docetaxel, carboplatin vs. paclitaxel and carboplatin vs. docetaxel. These associations were independent of cancer type, agents used to develop resistance and reported mechanisms of resistance. Sixty-five eligible clinical trials of paclitaxel-based salvage after platinum therapy were identified. Studies of single agent paclitaxel in platinum-resistant ovarian cancer where patients had previously recieved paclitaxel had a pooled response rate of 35.3%, n=232, compared to 22% in paclitaxel naïve patients n=1918 (p<0.01, Chi-squared). Suggesting that pre-treatment with paclitaxel may improve the response of salvage paclitaxel therapy. The response rate to paclitaxel/platinum combination regimens in platinum-sensitive ovarian cancer was 79.5%, n=88 compared to 49.4%, n=85 for paclitaxel combined with other agents (p<0.001, Chi-squared), suggesting a positive interaction between taxanes and platinum. Therefore, the inverse relationship between platinum and taxanes resistance seen in cell models is mirrored in the clinical response to these agents in ovarian cancer. An understanding of the cellular and molecular mechanisms responsible would be valuable in predicting response to salvage chemotherapy and may identify new therapeutic targets.

Factors affecting sensitivity to antitumor platinum derivatives of human colorectal tumor cell lines

PURPOSE

The aim of this study is to examine the factors affecting sensitivity to cisplatin, carboplatin, and oxaliplatin in human colorectal tumor cell lines.

METHODS

Caco-2, DLD-1, HCT-15, HCT116, LS180, SW620, and WiDr cells were used. Their growth inhibition by platinum derivatives was evaluated with a WST-1 assay utilizing succinate dehydrogenase activity. Cellular accumulation and DNA-binding of platinum were measured with an inductively coupled plasma mass spectrometer. The mRNA levels of copper transporters (hCtr1, ATP7A, and ATP7B) and organic cation transporters (hOCT1, hOCT2, and hOCT3) were evaluated by the real-time reverse transcription-PCR method using SYBR green.

RESULTS

The cytotoxicity of platinum derivatives ranked oxaliplatin > cisplatin > carboplatin in almost all cells used. Cellular accumulation and DNA-binding of platinum varied among the types of cells, but levels were similar on treatment with cisplatin and oxaliplatin, and lower in response to carboplatin. The levels of copper and organic cation transporter mRNAs also differed with cell type. A correlation analysis revealed that sensitivity to platinum derivatives was dependent in part on the amount of platinum bound to DNA. In addition, the cellular accumulation of platinum and level of ATP7A mRNA may be factors affecting the cytotoxicity of cisplatin, while the cytotoxicity of oxaliplatin was suggested to be affected by the levels of ATP7A and hOCT1 mRNAs.

CONCLUSION

Some factors affecting the sensitivity of tumor cells to platinum derivatives were proposed, and will provide useful information for cancer chemotherapy with platinum derivatives.

Effects of propolis extract on sensitivity to chemotherapeutic agents in HeLa and resistant sublines

The effects of a propolis extract obtained by supercritical fluid extraction on sensitivity to chemotherapeutic agents were examined in HeLa cells and resistant sublines thereof. In addition, the actions of propolis and caffeic acid phenethyl ester (CAPE), a constituent of propolis, on the multidrug efflux transporter P-glycoprotein/MDR1, were evaluated in paclitaxel-resistant HeLa/TXL cells (MDR1-overexpressing cells). In HeLa cells, the sensitivity to paclitaxel and doxorubicin, substrates of MDR1, was unchanged in the presence of propolis. In HeLa/TXL cells, propolis increased sensitivity to these MDR1 substrates. The accumulation of Rhodamine123, also a substrate for MDR1, by HeLa/TXL cells increased in the presence of 50 microg/mL, but not 10 microg/mL, of the extract. However, the growth inhibition of HeLa/TXL cells by paclitaxel was not changed by CAPE, although the accumulation of Rhodamine123 increased significantly in the presence of 100 microm, but not 1 nM or 1 microm, CAPE. Collectively, the extract was suggested to inhibit the function of MDR1 and to increase the sensitivity to MDR1 substrates in HeLa/TXL cells, effects likely to be caused by constituents other than CAPE.