CCDC134, a novel secretory protein, inhibits activation of ERK and JNK, but not p38 MAPK

In this study, we report a novel gene, CCDC134 (coiled-coil domain containing 134), that encodes a secretory protein that can inhibit the MAPK pathway as a novel human MAPK-regulating protein. The CCDC134 mRNA contains 1280 nucleotides, encoding a protein of 229 amino acids. CCDC134 is a classical secretory protein. Expression profile analysis by Northern blot, RT-PCR, immunohistochemistry and Western blot reveals that CCDC134 is widely expressed in normal adult tissues, tumor tissues and cell lines. Functional investigation reveals that overexpression of CCDC134 and its purified protein significantly inhibit transcriptional activity of Elk1 and phosphorylation of Erk and JNK/SAPK but not p38 MAPK. Conversely, specific siRNA against CCDC134 activates Elk1 transcriptional activity and promotes Erk and JNK/SAPK phosphorylation. These results clearly indicate that CCDC134 is a novel member of the secretory family and down-regulates the Raf-1/MEK/ERK and JNK/ SAPK pathways.

Using pseudo amino acid composition to predict transmembrane regions in protein: cellular automata and Lempel-Ziv complexity

Transmembrane (TM) proteins represent about 20-30% of the protein sequences in higher eukaryotes, playing important roles across a range of cellular functions. Moreover, knowledge about topology of these proteins often provides crucial hints toward their function. Due to the difficulties in experimental structure determinations of TM protein, theoretical prediction methods are highly preferred in identifying the topology of newly found ones according to their primary sequences, useful in both basic research and drug discovery. In this paper, based on the concept of pseudo amino acid composition (PseAA) that can incorporate sequence-order information of a protein sequence so as to remarkably enhance the power of discrete models (Chou, K. C., Proteins: Structure, Function, and Genetics, 2001, 43: 246-255), cellular automata and Lempel-Ziv complexity are introduced to predict the TM regions of integral membrane proteins including both alpha-helical and beta-barrel membrane proteins, validated by jackknife test. The result thus obtained is quite promising, which indicates that the current approach might be a quite potential high throughput tool in the post-genomic era. The source code and dataset are available for academic users at liml@scu.edu.cn.

Genetic polymorphisms involved in toxicant-metabolizing enzymes and the risk of chronic benzene poisoning in Chinese occupationally exposed populations

Benzene is a recognized haematotoxin and leukaemogen, but its mechanism of action and the role of genetic susceptibility are still unclear. Cytochrome P450 2E1 (CYP2E1) and myeloperoxidase (MPO) are involved in benzene activation; and NAD (P)H:quinine oxidoreductase 1 (NQO1), glutathione S-transferase theta 1 (GSTT1) and glutathione S-transferase mu 1 (GSTM1) participate in benzene detoxification. The common, well-studied single-nucleotide polymorphisms (SNPs) were analysed in these genes drawn from the toxicant-metabolizing pathways. A total of 100 workers with chronic benzene poisoning (CBP) and 90 controls were enrolled in China. There was a 2.82-fold (95% CI = 1.42-5.58) increased risk of CBP in the subjects with the NQO1 609C > T mutation genotype (T/T) compared with those carrying heterozygous (C/T) and wild-type (C/C). The subjects with the GSTT1 null genotype had a 1.91-fold (95% CI = 1.05-3.45) increased risk of CBP compared with those with GSTT1 non-null genotype. There was no association of CYP2E1 and MPO genotype with CBP. A three genes' interaction showed that there was a 20.41-fold (95% CI = 3.79-111.11) increased risk of CBP in subjects with the NQO1 609C > T T/T genotype and with the GSTT1 null genotype and the GSTM1 null genotype compared with those carrying the NQO1 609C > T C/T and C/C genotype, GSTT1 non-null genotype, and GSTM1 non-null genotype. The study provides evidence of an association of a gene-gene interaction with the risk of CBP.

Platelet activation in acute pulmonary embolism

BACKGROUND

Platelet activation is implicated in thrombotic disorders, but has not been described in acute clinical pulmonary embolism (PE).

OBJECTIVES

To investigate the natural history of platelet activation in PE and associated markers of inflammation, thrombosis and cardiac dysfunction.

METHODS

Thirty-five consecutive patients (age 62 +/-17 years) with acute PE were prospectively enrolled and followed for 6 months. Platelet activation was assessed by flow cytometry [measuring expression of platelet P-selectin, conformational activation of glycoprotein IIb/IIIa complex (PAC-1) and formation of platelet-leukocyte complexes] and by plasma soluble P-selectin. Platelet activation, right ventricular (RV) function (assessed as RV ejection area by transthoracic echocardiography), D-dimer and high-sensitivity C-reactive protein (hs-CRP) were measured at presentation and repeated over 6 months follow-up.

RESULTS

Soluble P-selectin (56 +/-19 ng mL(-1), anovaP < 0.0001) and PAC-1 (1.5 +/- 1.8%, anovaP = 0.005) were mildly but significantly increased in patients with acute PE relative to healthy young men (soluble P-selectin 33 +/- 13 ng mL(-1), P < 0.001; PAC-1 binding 0.5 +/- 0.6%, P < 0.01) and age-matched controls (soluble P-selectin 31 +/- 9 ng mL(-1), P < 0.001; PAC-1 binding 0.4 +/-0.4%, P < 0.05). Platelet P-selectin expression and platelet-leukocyte complexes were not increased during acute PE. Echocardiographic RV ejection area correlated inversely with soluble P-selectin (r = -0.47, P = 0.007) and positively with platelet P-selectin (r = 0.49, P = 0.0007), suggesting P-selectin is shed from activated platelets in proportion to the severity of RV dysfunction. Elevated soluble P-selectin, D-dimer and hs-CRP demonstrated a time-dependent return to normal during 6 months follow-up.

CONCLUSION

Platelet activation is evident after acute PE. Platelet activation correlates with the severity of RV dysfunction, and can persist for several months after acute PE.

Asynchronous administration of xenon and hypothermia significantly reduces brain infarction in the neonatal rat

BACKGROUND

Neonatal asphyxia causes long-term neurological and behavioural impairment in the developing brain. Concurrent administration of xenon and hypothermia synergistically reduces long-term damage in a rat model of neonatal asphyxia. This study sought to investigate whether asynchronous administration of xenon and hypothermia is capable of combining synergistically to provide neuroprotection.

METHODS

Seven-day-old rats were subjected to right common carotid artery occlusion followed by 90 min hypoxia with 8% oxygen. After a 1 h recovery period, rats received asynchronous administration of mild hypothermia (35 degrees C) and xenon (20%) with a 1 or 5 h gap between interventions, xenon (20%) alone, or mild hypothermia (35 degrees C) alone. Infarct volume in the brain was measured 4 days after injury.

RESULTS

Administration of hypothermia or xenon alone, 1 and 6 h after the hypoxic ischaemic insult, respectively, provided no neuroprotection. Asynchronous administration of xenon and hypothermia at a 1 h interval produced a significant reduction in infarct volume [93 (7) vs 74 (8); P < 0.05]. Reduction in infarct volume was also present when hypothermia and xenon were asynchronously administered with an intervening gap of 5 h [97 (5) vs 83 (3); P < 0.05].

CONCLUSIONS

This finding provides a rationale for investigating the combined use of hypothermia and xenon in a progressive manner for the management of neonatal asphyxia. Thus, hypothermia can be administrated at the site of delivery and xenon can be administered later.

A study on Notch signaling in human breast cancer

Breast cancer is one of the leading causes of cancer death in women. The Notch family of proteins plays crucial roles in determining cell fates such as proliferation, differentiation and apoptosis. A role for Notch signaling in human breast cancer has been suggested by the development of adenocarcinomas in the murine mammary gland. However, it is not clear currently whether Notch signaling is frequently expressed and activated in breast cancers. Here we show that Notch signaling is overexpressed and highly activated in breast cancers. More significantly, the attenuation of Notch signaling by gamma-secretase inhibitor can inhibit the proliferation of breast cancer cells by both causing cell cycle arrest and apoptosis. Thus, targeting Notch signaling may be of therapeutic value in breast cancers.

Studies of pemetrexed and gemcitabine, alone and in combinations, in human lung cancer models

17114

Background: Gemcitabine (GEM) is a deoxycytidine analog that inhibits DNA synthesis. Pemetrexed (ALIMTA, PEM) is a novel antifolate inhibiting multiple enzymes targets, including thymidylate synthase (TS). This study aimed at evaluating the antitumor effects of these antimetabolites against NSCLC and SCLC tumor models. Methods: In vitro growth inhibition (IC50) studies were done by 6-days MTT assays against a panel of 20 NSCLC and 17 SCLC cell lines. In vivo studies used only NSCLC H2122 tumor line, implanted either subcutaneously in athymic nude mice or orthotopically in athymic nude rats. Drugs were given via the ip route at the designated schedules. Results: Against NSCLC and SCLC cell lines, the averaged IC50s of GEM were 0.015 ± 0.008 μM and 0.055 ± 0.04 μM respectively. The corresponding averaged IC50s for PEM were 0.65 ± 0.2 μM and 0.091±0.018 μM respectively. When H2122 tumors reached 50–100mg, mice were treated with 10 daily doses of PEM at 100, 200 and 300 mg/kg, or three doses of GEM every 4 days at 30, 60 and 120 mg/kg. PEM delayed tumor growth by 12 to 18 days, and GEM delayed by 10 to 14 days, relative to vehicle control. Results of three combination regimens with GEM (30 mg/kg) and PEM (100 mg/kg) were: (1) GEM → PEM gave intermediate activities between the two single agents, but was toxic to animals; (2) PEM and GEM given concurrently were more active than single agents alone and delayed tumor growth by 12 days with some toxic side effects; (3) PEM → GEM was better than the single agents alone, and delayed tumor growth by ∼14 days without toxicity. Athymic nude rats bearing orthotopic H2122 tumors given PEM daily at 50, 100 and 200 mg/kg for 21 days had significantly prolonged survival, but not in a dose-dependent manner. PEM at 50 mg/kg was more effective than doses at 100 or 200 mg/kg. GEM was toxic to nude rats due to poor plasma deamination of GEM. Conclusions: In vitro, PEM was more potent against SCLC than NSCLC cell lines, but GEM had similar activities against all lung lines tested. Studies of H2122 xenografts in rodent supported PEM → GEM as the preferred sequence for the combined administration of these two drugs.

[Table: see text]

Thymidylate synthase gene expression in solid tumors predicts for response to pemetrexed in vitro

13058

Background: Pemetrexed (P) is a novel antifolate which targets thymidilate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT). The aim of the present study was to identify gene expression thresholds for these enzymes in human tumor specimens in order to separate P-sensitive from P-resistant patients. Methods: Soft-agar cloning assays were performed on freshly biopsied tumor cells exposed one hour to clinically achievable concentrations of P. In parallel, RNA was isolated, transcribed to cDNA and subsequently used for multiplex real-time PCR. Gene expression data were normalized against beta-actin transcripts followed by correlation against cloning assay results. Iterative calculations (fourfold analysis) were done for each enzyme separately to find the best cutoff for prediction of sensitivity to P. Results: Sensitive and resistant tumor samples were statistically significant different in gene expression of TS, DHFR, and GARFT (p < 0.003). 81% of all tumors with a TS copy number < 144 (related to 104 copies β-actin) were sensitive to P in vitro. (specificity = 0.69; chi2 = 14.14). Statistical tests demonstrated that gene expression of TS, DHFR, and GARFT are dependent variables and that TS transcription is the leading variable. The combination of TS, DHFR, and GARFT expression data was not superior to TS alone. Conclusions: TS expression is the most meaningful predictor for sensitivity (≤ 144 copies) or resistance (> 144 copies) to Pemetrexed in fresh tumor tissue. This observation forms a rationale for clinical trials using TS expression as predictor for clinical response.

No significant financial relationships to disclose.

Expression profiles can predict both general chemotherapy and gemcitabine-specific responses in breast cancer patients receiving neoadjuvant therapy

10008

Background: The identification of markers predictive of neoadjuvant chemotherapy response would be an important advance. Therefore, we sought to identify gene expression profiles predictive of neoadjuvant response and evaluated their drug specificity. Methods: DNA microarray analysis was performed on pre-treatment core biopsies from two different locally advanced breast cancer patient sets receiving neoadjuvant chemotherapy; the first set (L9819) was treated with 4 cycles of doxorubicin + cyclophosphamide (AC) followed by 4 cycles of paclitaxel (T) or paclitaxel + trastuzumab (TH). The second patient set (S329) received 4 cycles of gemcitabine + doxorubicin followed by 4 cycles of gemcitabine + cisplatin. Clinical response was based on RECIST criteria. Results: We obtained successful microarrays on 44 (L9819) and 46 (S329) of the patients enrolled. Ten-fold cross-validated supervised analyses separately performed on each dataset identified gene expression patterns that accurately predicted (75–85% accuracy) response (clinical complete responders vs. others) evaluated on those patients that completed all 8 cycles of chemotherapy. The predictive expression patterns from the L9819 trial were significantly enriched for apoptosis genes, while the predictive gene set from the S329 trial was enriched for nucleotide metabolism genes. The L9819 predictor was able to accurately predict (75% accuracy) response for the S329 patients, however, the S329 predictor was not able to predict response on the L9819 trial (50% accuracy). We speculate that the L9819 predictor was able to predict response on the S329 dataset (despite the fact that only doxorubicin was common to both trials) because this profile was enriched for apoptosis genes that may reflect a general mechanism of chemotherapy response/resistance, while the S329 predictor was more tuned to gemcitabine’s specific mechanism of action. Conclusions: This study may provide the means to predict response to AC-T(H) and GA-GC neoadjuvant chemotherapy. The ability of one predictor to work on the other dataset, but not vise versa, suggests that both general chemotherapy and drug specific response profiles may have been identified.

[Table: see text]

Randomized, phase II study of two doses of pemetrexed as first-line chemotherapy for locally advanced or metastatic breast cancer (MBC): Clinical results and exploratory pharmacogenomic analysis

3077

Background: Pemetrexed, a folate antimetabolite, has shown varied response in MBC, depending on the dose, vitamin supplementation, and patient pre-treatment status. We conducted a randomized, double-blind, phase II study, in patients with locally advanced or MBC to evaluate 2 doses of pemetrexed. Primary objective was to assess the response rates on the 2 arms. Methods: Women with histologic/cytologic diagnosis of breast cancer, evidence of locally recurrent disease or distant metastasis, not amenable to local therapy were eligible. Patients received pemetrexed (600 mg/m2 Arm A; or 900 mg/m2 Arm B), on D1 of a 21-day cycle. All patients received folic acid and vitamin B12 supplementation. Forty-three patients were planned on each arm. Results: Ninety-two patients (median age 57 years, range 33–81) enrolled: 47 on arm A and 45 on arm B. Arms A and B had response rates of 17.0% (95% CI, 7.7%-30.8%), and 15.6% (95% CI, 6.5%-29.5%), median progression free survival times of 4.2 and 4.1 months, and median times to tumor progression (TtTP) of 4.2 and 4.6 months, respectively. On both arms, a median of 6 cycles was delivered. Toxicity was mild (grade 3/4 toxicity on both arms; neutropenia <20%, leucopenia <9%). Primary tumor samples from 49 patients were assessed for 10 folate or pyrimidine metabolism related gene expressions by reverse transcriptase-polymerase chain reaction methodology. Two markers, folypolyglutamate synthase (FPGS) and thymidine phosphorylase (TP), showed significant results. Best response rates and median TtTP for high vs low FPGS expression subgroups were 37.5% vs 10.0% and 8.6 vs 3.0 months. The corresponding results for TP were 27.6% vs 6.3% and 5.4 vs 1.9 months. Conclusions: Efficacy and safety of the two pemetrexed doses were similar; thus, the lower dose (600 mg/m2) is suitable in patients with MBC. Exploratory biomarker analysis suggests efficacy correlation for FPGS and TP. Further evaluation of these markers appears warranted.

[Table: see text]

Enzastaurin a protein kinase Cbeta-selective inhibitor, inhibits the growth of SCLC and NSCLC cell lines

13138

Background: PKCβ is a member of the PKC family of serine-threonine protein kinases involved in tumor cell proliferation and apoptosis. Inhibition of PKCs induced differentiation and enhanced chemotherapy. PKCβ activation is required for tumor-induced angiogenesis. The PKCβ-selective inhibitor enzastaurin, originally developed as an antiangiogenic agent, inhibited tumor cell proliferation in prostate, colon and glioblastoma cell lines in vitro. In NSCLC lines, enhanced phosphorylation and altered PKC expression was demonstrated. In SCLC lines specific PKC isoforms were associated with cisplatin resistance. Methods: The growth inhibitory effects of enzastaruin were evaluated by 6-day MTT assays; the cell cycle effects by FACS analysis; the effects on downstream phophorylated signaling molecules by western blotting. Results: Enzastaurin inhibited the growth of 11 SCLC lines (IC50s 3–10 μM) and 4 NSCLC cell lines (IC50s 3–10 μM). An increase of 7–31% of cells in the G2/M phase of the cell cycle compared to untreated control was observed following 48 hour exposure to the IC50 dose of enzastaurin in both SCLC and NSCLC cell lines. PKCβ has been shown to phosphorylate both GSK3β and Akt. A 24-hour IC50 enzastaurin exposure significantly reduced phosphorylation of GSK3β (Ser9) in both SCLC and NSCLC lines. No changes were observed in phospho-AKT (Thr308) in either SCLC or NSCLC cell lines. Phospho-ribosomal protein S6 (Ser240/244) was also reduced in both SCLC and NSCLC cell lines. Potential synergy was studied between enzastaurin and pemetrexed in SCLC and NSCLC lines and the results were analyzed using the Calcusyn Program by Chou and Talalay. Synergistic (CI <1) to additive interactions were observed between pemetrexed (IC20–70) and enzastaurin (≤ IC50) in both SCLC lines (N = 3) and NSCLC lines (N = 2). Conclusions: We conclude that enzastaruin produces in vitro growth inhibition of SCLC and NSCLC cell lines through inhibition of GSK3β ser9 phosphorylation and has synergistic growth inhibition with pemetrexed.

[Table: see text]

In vitro chemosensitivity against enzastaurin correlates with gene expression of IL8 and GSK3-beta

13046

Background: Enzastaurin (E) is an active antitumoral agent which selectively inhibits the β-isoform of protein kinase C (PKC-β). The compound blocks the enzyme’s ATP-binding site and signal transmission is abrogated resulting in the inhibition of neovascularization. The aim of the present study was to correlate gene expression with in vitro chemosensitivity of freshly explanted human tumor specimens. Such correlations in tumors taken directly from patients will help to rationally design subsequent clinical trials. Methods: Soft-agar colony forming assays were performed on freshly biopsied tumor cells exposed to various concentrations of E. Corresponding pieces of tumor specimens were shock-frozen and prepared for RNA isolation and cDNA generation followed by multiplex real-time PCR experiments. Gene expression data were correlated against cloning assay results. Results: Gene expression data of PKC-β1, PKC-β2, IL8RA, IL8RB, IL8, GSK3-β, and TGF-β were correlated against in vitro chemosensitivity pattern of E from 66 samples. After 1h-drug exposure gene expressions in sensitive versus resistant specimens were statistically significant with p = 0.013 for IL8 [median copy number (mcn): 1881 vs. 694; n = 66] and p = 0.012 for GSK3-beta (mcn: 1.6 vs. 7.0; n = 66). No correlation was detected for PKC-β1, PKC-β2, IL8RA, and IL8RB. Detection of TGF-β failed in most samples. Conclusions: Low expression of GSK3-β and high expression of IL8 correlate statistically significantly with increased in vitro sensitivity to E in freshly explanted human tumors. These findings may help direct further clinical development of this compound.

No significant financial relationships to disclose.

Oncolytic adenovirus-mediated transfer of the antisense chk2 selectively inhibits tumor growth in vitro and in vivo

Screening and identifying molecules target to checkpoint pathways has fostered the development of checkpoint-based anticancer strategies. Among these targets, inhibition of chk2 may induce cell death for tumors whose growth depends on enhanced chk2 activity. However, improvement of the potency and specificity of such therapeutics remains a major challenge. To resolve this problem, we constructed M3, a novel recombinant adenovirus with a 27-bp deletion in E1A CR2 region by which to realize tumor-specific replication, and an 829-bp of antisense chk2 fragment inserted into the E3 coding region. In this design, M3 exploited the native adenovirus E3 promoters to express antisense chk2 cDNA in a viral replication-dependent fashion, and preferentially silenced the chk2 gene in tumor cells. In vitro and in vivo assays confirmed that downregulated chk2 expression induced by M3 infection was tumor-specific and virus replication-dependent. Furthermore, systemic administration of M3 combined with a low dose of cisplatin cured 75% (9/12) of orthotopic hepatic carcinoma mouse models that were otherwise resistant to cisplatin. Our results indicated that the upcoming development in this field would improve the antitumor efficacy and maximize the synergistic effect of oncolytic viruses administered with traditional chemotherapy or radiotherapy.

Procaspase-3 enhances the in vitro effect of cytosine deaminase-thymidine kinase disuicide gene therapy on human ovarian cancer

Because the efficacy of genetic prodrug activation therapy (GPAT) using herpes simplex virus thymidine kinase (tk)/ganciclovir (GCV) or Escherichia coli cytosine deaminase (cd)/5-fluorocytosine (5-FC) is not satisfied in early clinical trials and the mechanism of both the GPATs have been shown to lead to the activation of cell apoptotic pathway, we hypothesized that coexpression of procaspase-3, a central downstream executioner of apoptotic pathways, with cd-tk gene leads to enhanced cell death in ovarian cancer cells in vitro. Following transfection with the vectors encoding cd and tk, 5-FC and GCV treatments lead to greater cell death in procaspase-3-expressing clones of 3AO (3AO-caspase-3) than control cells (3AO-pcDNA3), as well as more rapid activation of caspase-3 and more rapid cleavage of poly (adenosine diphosphate-ribose) polymerase (PARP). There is a greater degree of cell apoptotic rate in the procaspase-3-expressing clones than in control cells following the treatment with cd-tk/5-FC + GCV, and apoptosis is the main cell death form. None of these effects is seen following transfection with a control vector that does not encode tk and cd (pBTdel-279). The results strongly suggest that coexpression of procaspase-3 may lead to a significant enhancement of the efficacy of cd-tk/5-FC + GCV, and this strategy would be a novel and promising approach for the treatment of ovarian cancer.

Inhibition of ovarian cancer metastasis by adeno-associated virus-mediated gene transfer of nm23H1 in an orthotopic implantation model

Ovarian cancer is one of the most threatening malignant tumors in females due to the frequent occurrence of metastasis that precedes diagnosis. The present study explored the possibility of preventing ovarian cancer metastasis by promoting nm23H1 expression through adeno-associated virus (AAV)-mediated gene transfer. A cell line of high metastatic potential, SW626-M4, was derived by in vivo selection and used to establish an ovarian cancer metastasis model in the mouse. Liver metastasis and animal survival time were measured after transfer of a recombinant adeno-associated viral vector expressing nm23H1 (AAV-nm23H1) into the aforementioned model. Intraperitoneal injection of AAV-nm23H1 into this orthotopic implantation model of ovarian cancer resulted in (1) expression of the exogenous gene in more than 95% of tumor cells in situ in nude mice; (2) a 60% reduction in the number of animals developing liver metastases; and (3) a 35-day prolongation of median survival time compared with the untreated host group. In conclusion, the results support the feasibility of induction of nm23H1 expression through gene transfer as a therapeutic strategy for preventing metastases and prolonging host survival time, and indicate that AAV vectors deserve attention in the design of future gene therapy approaches to achieving long-term expression of curative genes in vivo.

Inhibition of telomerase enhances apoptosis induced by sodium butyrate via mitochondrial pathway

Telomerase activation represents an early step in carcinogenesis. Increased telomerase activity in cervical cancer suggests a potential target for the development of novel therapeutic drugs. The aim of this study is to investigate the impact of telomerase activity on the biological features of HeLa cells and the possible mechanisms of enhanced apoptosis rate induced by sodium butyrate after telomerase inhibition. We introduced vectors encoding dominate negative (DN)-hTERT, wild-type (WT)-hTERT, or a control vector expressing only a drug-resistance marker into HeLa cells. Thus we assessed the biological effects of telomerase activity on telomere length, cell proliferation, chemosensitivity and radiosensitivity. In order to understand the mechanisms in which DN-hTERT enhances the apoptosis induced by sodium butyrate, we detected the release status of cytochrome c and apoptosis inducing factor (AIF) from mitochondria. Ectopic expression of DN-hTERT resulted in inhibition of telomerase activity, reduction of telomere length, decreased colony formation ability, and loss of tumorigenicity in nude mice. Moreover, DN-hTERT transfected HeLa cells with shortened telomeres were more susceptible to multiple chemotherapeutic agents and radiation. WT-hTERT transfected HeLa cells with longer telomeres exhibited resistance to radiation and chemotherapeutic agents. Our data demonstrate that elevated release level of cytochrome c and AIF from mitochondria might contribute to the enhanced apoptosis in DN-hTERT transfected HeLa cells after treatment with sodium butyrate. Inhibition of telomerase might serve as a promising adjunctive therapy combined with conventional therapy in cervical cancer.

Breast cancer resistance protein-mediated topotecan resistance in ovarian cancer cells

Overexpression of breast cancer resistance protein (BCRP) and mitoxantrone (MX) resistance protein can confer resistance to a variety of cytostatic drugs, such as MX, topotecan (TPT), doxorubicin, and daunorubicin. This study investigates the role of BCRP in resistance of ovarian cancer to TPT treatment. We have developed TPT-resistant human ovarian cancer cell line. Intracellular concentration of fluorescent dye rhodamine 123 (Rh123) was measured by flow cytometry. The expression of several membrane transporter proteins including P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and BCRP were determined by reverse transcription-polymerase chain reaction and Western blotting. The Rh123 concentration in parental cells was approximately three times of those in TPT-resistant cells. In contrast to undetectable level of P-gp messenger RNA (mRNA) and minimal level of MRP1 expression in TPT-resistant cells, overexpression of both the BCRP mRNA and the protein was detected in these cells. Introduction of antisense-phosphorothioate oligonucleotide derived from BCRP mRNA into TPT-resistant cells resulted in a significant increase in the concentration of intracellular Rh123. These results suggested a novel mechanism in which a reduced intracellular drug concentration may be mediated by BCRP gene products in human ovarian cancer cells.

Arsenic trioxide induces apoptosis in cisplatin-sensitive and -resistant ovarian cancer cell lines

Arsenic trioxide (As(2)O(3)), has been used for centuries in traditional Chinese medicine; it has considerable efficacy in the treatment of relapsed acute promyelocytic leukemia, inducing partial differentiation and promoting apoptosis of malignant promyelocytes. Although a number of studies have demonstrated that As(2)O(3) has potent activity against cell growth in a series of leukemia cell lines, little information is available regarding this compound's effect on cell growth in solid tumor cell lines. In this study, we investigated the effects of As(2)O(3)in vitro on ovarian cancer cell lines sensitive (3AO) and resistant (3AO/CDDP) to cisplatin. The 3-(4,5-dimethy-thiazoyl-2-yl)-2,5-diphenyl-tetrazolium bromide assay was used to evaluate cytotoxicity. Flow cytometric analysis was used to determine the apoptosis, cell cycle distribution. We clearly demonstrated that As(2)O(3) induced cell apoptosis and inhibition of cell growth in both the cell lines. Furthermore, we identified that As(2)O(3)-induced apoptosis involved Fas pathway. As(2)O(3) is an active agent against ovarian cancer cells and could be effective in the clinical treatment of ovarian cancer.

Isoflurane exerts antinociceptive and hypnotic properties at all ages in Fischer rats

BACKGROUND

Some anaesthetic agents exhibit an age-dependent analgesic effect, for example nitrous oxide, which is ineffective in newborn rats. We investigated whether a similar time dependency existed for the responses to the volatile anaesthetic isoflurane.

METHODS

The analgesic and hypnotic properties of isoflurane at various ages was assessed using four cohorts of Fischer rats aged approximately 7, 16, and 28 days and adults (11-12 weeks old). Intraplantar administration of formalin mimicked inflammatory pain, and its effects were assessed using immunohistochemical (c-Fos staining) and behavioural paradigms. The hypnotic properties of isoflurane were assessed using loss of righting reflex.

RESULTS

Formalin administration produced a typical nociceptive response observed both behaviourally and immunohistochemically in all age groups; these nociceptive responses were significantly attenuated by isoflurane 0.5% at each age (P<0.05). Interestingly 7-day-old animals showed a significantly more potent hypnotic response than older animals (P<0.01): with adult rats being most resistant to isoflurane induced hypnosis (P<0.05).

CONCLUSION

In contrast to nitrous oxide, isoflurane is an effective antinociceptive agent in neonatal rats. If the data can be extrapolated to clinical scenarios these results suggest that isoflurane may be analgesic in newborns as well as adult humans. In addition, isoflurane is a potent hypnotic, especially in the very young, which is in contrast to the neonate's relative resistance to anaesthesia as assessed by minimum alveolar concentration.