Ross Davey | The University of Sydney (original) (raw)
Papers by Ross Davey
Physics in Medicine and Biology, 2009
In this study we present two prediction methods, mean dose and summed dose, for predicting the nu... more In this study we present two prediction methods, mean dose and summed dose, for predicting the number of A549 cells that will survive after modulated x-ray irradiation. The prediction methods incorporate the dose profile from the modulated x-ray fluence map applied across the cell sample and the linear quadratic (LQ) model. We investigated the clonogenic survival of A549 cells when irradiated using two different modulated x-ray fluence maps. Differences between the measured and predicted surviving fraction were observed for modulated x-ray irradiation. When the x-ray fluence map produced a steep dose gradient across the sample, fewer cells survived in the unirradiated region than expected. When the x-ray fluence map produced a less steep dose gradient across the sample, more cells survived in the unirradiated region than expected. Regardless of the steepness of the dose gradient, more cells survived in the irradiated region than expected for the reference dose range of 1-10 Gy. The change in the cell survival for the unirradiated regions of the two different dose gradients may be an important factor to consider when predicting the number of cells that will survive at the edge of modulated x-ray fields. This investigation provides an improved method of predicting cell survival for modulated x-ray radiation treatment. It highlights the limitations of the LQ model, particularly in its ability to describe the biological response of cells irradiated under these conditions.
Leukemia Research, 2001
Recent reports have correlated multidrug resistance (MDR) and P-glycoprotein expression with decr... more Recent reports have correlated multidrug resistance (MDR) and P-glycoprotein expression with decreased Fas expression and resistance to Fas-mediated apoptosis. We report the MRP-overexpressing MDR subline CEM/E1000 has the same Fas expression (MFI 74.3 90.7) as the parental CCRF-CEM T-cell leukaemia cells (MFI 70.0 93.6; P \ 0.05), and that the level of apoptosis induced by anti-Fas antibody or drug was similar in both cell lines. Further the P-glycoprotein-expressing CEM/VLB 100 subline of the CCRF-CEM cells showed increased Fas expression (MFI 114.8 9 3.6; PB0.001) and no resistance to Fas-mediated apoptosis. This questions the hypothesis that selection of drug resistance results in resistance to Fas-mediated apoptosis, with important implications for the rational use of immunotherapy in the treatment of drug resistant cancer.
International Journal of Cancer, 1998
The H82 "variant" and the H69 "classic" small cell lung cance... more The H82 "variant" and the H69 "classic" small cell lung cancer (SCLC) cell lines were treated with low levels of epirubicin (69 and 14 nM) which caused little cell death but produced the H82/E8 and H69/E8 extended-multidrug resistant sublines. Both were resistant to drugs associated with multidrug resistance (MDR), and to chlorambucil (9.5- and 5.6-fold, respectively) and cisplatin (2.3- and 8.5-fold, respectively). There was increased expression of the multidrug resistance-associated protein (MRP1) in the H82/E8 subline while P-glycoprotein expression was not detected in any cells or sublines. Treatment of the H82 cells for 1 hr with 69 nM epirubicin increased MRP1-mRNA expression within 4 hr and this was associated with an increase in the resistance to epirubicin, chlorambucil, cisplatin and paclitaxel. Further, a 1 hr treatment with non-cytotoxic doses of chlorambucil (2.5 microM), cisplatin (1.3 microM) or paclitaxel (13 nM), drugs not normally associated with MRP1-mediated MDR, also increased MRP1-mRNA expression in the H82 cells with paclitaxel causing the highest increase (4.5-fold). For chlorambucil treatment, this increased MRPI-mRNA expression was accompanied by increased drug resistance while paclitaxel treatment had no effect on drug resistance in the H82 cells. For the drug resistant H82/E8 subline, these drug treatments had no effect on the MRP1-mRNA expression and little effect on increasing the subline drug resistance. However, pretreatment with paclitaxel sensitised the H82/E8 subline to chlorambucil and cisplatin returning the subline to the sensitivity of the H82 cell line. We conclude that treatment with low levels of MDR and non-MDR drugs can induce extended-multidrug resistance in SCLC cells, a process that probably involves the co-ordinate upregulation of MRP1 and other resistance mechanisms. The results also suggest paclitaxel may have a role as a response modifier in the treatment of refractory SCLC.
British Journal of Haematology, 1994
In an attempt to mimic clinical conditions for the treatment of leukaemia, the HL60 promyelocytic... more In an attempt to mimic clinical conditions for the treatment of leukaemia, the HL60 promyelocytic cell line was treated for 18 h with low, clinically relevant, levels of the anthracycline epirubicin and the Vincu alkaloid
British Journal of Haematology, 1999
Relative to the commonly used anthracyclines, little is known about idarubicin and the developmen... more Relative to the commonly used anthracyclines, little is known about idarubicin and the development of multidrug resistance. We have previously shown the K562/IDA subline resulting from intermittent treatment of the K562 human leukaemia cell line with 20 ng/ml idarubicin did not develop multidrug resistance but became more sensitive to etoposide. Additional similar treatments of this subline produced the K562/IDA20 subline which partially retained its etoposide sensitivity although these cells expressed P-glycoprotein and were resistant to paclitaxel. Sensitization to etoposide was associated with increased decatenation activity of topoisomerase II, although there were no changes in topoisomerase IIalpha expression or formation of etoposide-dependent cleavable complexes. In comparison, the K562/IDA10 subline produced by intermittent treatment of the K562 cells, firstly with 5 ng/ml then 10 ng/ml idarubicin, showed no detectable expression of P-glycoprotein, decreased topoisomerase IIalpha expression and increased resistance to etoposide and amsacrine, but not to idarubicin or genistein. Even though intermittent treatment with idarubicin caused increased drug resistance in both sublines, they remained sensitive to idarubicin. Therefore the potential of idarubicin as a substitute for other anthracyclines in the treatment of cancer warrants further investigation.
Biochemical Pharmacology, 1995
With the increasing use of inducers of cellular differentiation in the treatment of leukaemia, it... more With the increasing use of inducers of cellular differentiation in the treatment of leukaemia, it is essential to understand the relationship between differentiation and the expression of the multidrug resistance. Using the K562 human leukaemia cell line and its multidrug resistant subline K562/E15B, differentiation was examined along two different pathways, megakaryocyte in response to treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA), and erythroid in response to treatment with sodium butyrate, in the same cell line. P-glycoprotein expression was increased in the multidrug resistant K562/E15B subline, but not induced in the parental K562 cell line. However, both treatments conferred a different phenotype on the drug resistant subline. TPA treatment caused an increase in P-glycoprotein, increased drug resistance and decreased rhodamine-123 accumulation which was verapamil sensitive, demonstrating that TPA induced a fully functional P-glycoprotein. However, sodium butyrate treatment caused an increase in P-glycoprotein without increased drug resistance or without decreased rhodamine-123 accumulation suggesting that the P-glycoprotein induced by sodium butyrate was nonfunctional. These results stress the importance of examining not only the expression of P-glycoprotein in cells, but also the function of the P-glycoprotein induced.
Near diploid leukemic T-cells (LALW-2), exposed to cytotoxic drugs only as a consequence of thera... more Near diploid leukemic T-cells (LALW-2), exposed to cytotoxic drugs only as a consequence of therapy administered to the donor patient, have been maintained by serial xenograft in nude mice. In comparison with the leukemic line CCRF-CEM, using a growth inhibition assay, LALW- 2 cells were resistant to Vinca alkaloids and actinomycin D (relative resistance, 200-fold or more), were slightly resistant
Platinum and Other Heavy Metal Compounds in Cancer Chemotherapy, 2009
The H69CIS200 and H69OX400 cell lines are novel models of low-level platinum drug resistance deve... more The H69CIS200 and H69OX400 cell lines are novel models of low-level platinum drug resistance developed from H69 human small cell lung cancer cells with eight 4day treatments of 200 ng/ml cisplatin or 400 ng/ml oxaliplatin respectively. A recovery period was given between treatments to emulate the cycles of chemotherapy given in the clinic. The resistant cell lines were approximately 2-fold resistant to cisplatin and oxaliplatin and were cross resistant to both drugs. Platinum resistance was not associated with increased cellular glutathione, decreased accumulation of platinum or increased DNA repair capacity. The H69 platinum sensitive cells entered a lengthy 3 week growth arrest in response to low-level cisplatin or oxaliplatin treatment. This is an example of the coordinated response between the cell cycle and DNA repair. In contrast the H69CIS200 and H69OX400 cells have an alteration in the cell cycle allowing them to rapidly proliferate post drug treatment. The resistant cell lines also have many chromosomal rearrangements most of which are not associated with the resistant phenotype, suggesting an increase in genomic instability in the resistant cell lines. We hypothesised that there was a lack of coordination between the
Cancer chemotherapy and pharmacology, 1997
The effectiveness of N-[2-(dimethylamino)ethyl]acridine-4-carboxamide (DACA) relative to that of ... more The effectiveness of N-[2-(dimethylamino)ethyl]acridine-4-carboxamide (DACA) relative to that of amsacrine, idarubicin, daunorubicin and paclitaxel against three different forms of multidrug resistance (MDR) was determined using two sublines of the CCRF-CEM human leukaemia cell line, the P-glyco-protein-expressing CEM/VLB100 subline and the MRP-expressing CEM/E1000 subline, and two extended-MDR sublines of the HL60 human leukaemia cell line, HL60/E8 and HL60/V8. DACA was effective against P-glycoprotein-mediated MDR and MRP-mediated MDR, whereas the extended-MDR phenotype showed only low levels of resistance (< 2-fold) to DACA. In comparison, idarubicin was ineffective against the MRP and extended-MDR phenotypes. Repeated exposure of the K562 human leukaemia cell line to DACA (55, 546 or 1092 nM for 3 days over 10 weeks) did not result in the development of any significant drug resistance. We conclude that DACA has the potential to treat refractory leukaemia.
Cytometry, 2001
Background: Multidrug resistance (MDR) is mediated by the drug resistance proteins, the multidrug... more Background: Multidrug resistance (MDR) is mediated by the drug resistance proteins, the multidrug resistanceassociated protein (MRP) and P-glycoprotein, both of which confer resistance by the active efflux of chemotherapeutic drugs from the cell. Reduced Fas (CD95/APO-1) expression and resistance to Fas-mediated apoptosis have also been correlated with P-glycoprotein-mediated MDR. Methods: We investigated cell surface Fas expression (using anti-Fas monoclonal antibody DX2.1) in a series of MRP-expressing drug-resistant leukemia sublines, and Pglycoprotein-expressing leukemia sublines, and their susceptibility to apoptosis induced by anti-Fas treatment (CH-11 monoclonal antibody). Caspase-3 activation was detected by Western blot and apoptosis was determined by flow cytometry with 7-aminoactinomycin D (7-AAD) staining of cells.
Platinum and Other Heavy Metal Compounds in Cancer Chemotherapy, 2009
Objective: To examine the pre-clinical and clinical evidence for the use of oxaliplatin or paclit... more Objective: To examine the pre-clinical and clinical evidence for the use of oxaliplatin or paclitaxel salvage chemotherapy in patients with cisplatin-resistant cancer. Methods: Medline was searched for 1) Cell models of acquired resistance reporting cisplatin, oxaliplatin and paclitaxel sensitivities and 2) Clinical trials of single agent oxaliplatin or paclitaxel salvage therapy for cisplatin/carboplatin-resistant ovarian cancer. Results: Oxaliplatin -Oxaliplatin is widely regarded as being active in cisplatin-resistant cancer. In contrast, data in cell models suggests that there is crossresistance between cisplatin and oxaliplatin in cellular models with resistance levels which reflect clinical resistance (<10 fold). Oxaliplatin as a single agent had a poor response rate in patients with cisplatin-resistant ovarian cancer (8%, n=91).
Cancer immunology research, 2014
Induction of antitumor immunity using autologous tumor proteins is an attractive approach to canc... more Induction of antitumor immunity using autologous tumor proteins is an attractive approach to cancer therapy. However, better methods and stimulants to present these autologous proteins back to the immune system are needed. Here, we identify streptavidin as a novel carrier protein and stimulant, and test the efficacy of both syngeneic (rat) and autologous vaccines (dogs) using streptavidin in combination with reduced soluble tumor proteins. Initial syngeneic vaccine studies in the 9L rat glioma model were used to optimize vaccine dose and selectivity. Cytokine and blood analysis was used to monitor the response. Rats receiving two vaccinations of syngeneic tumor vaccine demonstrated a statistically significant (P < 0.05) survival advantage compared with controls (adjuvant only). Notably, vaccination also led to remission rates of between 30% and 60% in the aggressive 9L glioma model. Antibodies to streptavidin were detected in the serum of vaccinated rats; however, antibody levels...
Cytometry, 2001
Recent studies have shown that paclitaxel (Taxol) is an active chemotherapeutic in the treatment ... more Recent studies have shown that paclitaxel (Taxol) is an active chemotherapeutic in the treatment of small cell lung cancer. Paclitaxel binds to tubulin and prevents depolymerization. This causes cells to arrest in the G 2 /M phase of the cell cycle, resulting in sensitization of cells to drug or radiation treatment. Methods: A drug-resistant H69 small cell lung cancer subline was established. Cytotoxicity of cisplatin and chlorambucil was determined using the MTT cell viability assay and distribution of DNA in the cell cycle. DNA distribution was analyzed by flow cytometry after treatment with paclitaxel or the other tubulin-binding drugs, vinblastine and navelbine. Results: The H69-EPR drug-resistant subline was resistant to epirubicin (sixfold) and was cross-resistant to cisplatin (7.5-fold) and chlorambucil (7.5-fold). Pretreatment with paclitaxel or vinblastine, but not navelbine, sensitized the subline to cisplatin and chlorambucil (P Ͻ 0.05), with no effect on parental H69 cells. Sensitization was dose dependent and occurred at doses below those that caused a G 2 /M block in the cell cycle. Conclusion: Sensitization of drug-resistant cells by paclitaxel was not associated with its ability to cause a G 2 /M block in the cell cycle. Sensitization by paclitaxel and vinblastine, but not navelbine, which preferentially targets mitotic tubulin, suggests that sensitization may involve changes in the tubulin-dependent intracellular transport processes rather than changes in mitotic tubulin and the G 2 /M block.
Wound Repair and Regeneration, 2005
Activated protein C (APC) is a serine protease that plays a central role in physiological anticoa... more Activated protein C (APC) is a serine protease that plays a central role in physiological anticoagulation, and has more recently been shown to be a potent anti-inflammatory mediator. Using cultured human cells, we show here that APC up-regulates the angiogenic promoters matrix metalloproteinase-2 in skin fibroblasts and umbilical vein endothelial cells, vascular endothelial growth factor in keratinocytes and fibroblasts, and monocyte chemoattractant protein-1 in fibroblasts. In the chick embryo chorioallantoic membrane assay, APC promoted the granulation/remodeling phases of wound healing by markedly stimulating angiogenesis as well as promoting reepithelialization. In a full-thickness rat skin-healing model, a single topical application of APC enhanced wound healing compared to saline control. APC-treated wounds had markedly more blood vessels on day 7 and a significantly lower infiltration of neutrophils at days 4 and 7. The broad spectrum matrix metallo-proteinas, GM6001, prevented the ability of APC to promote wound healing. In summary, our results show that APC promotes cutaneous wound healing via a complex mechanism involving stimulation of angiogenesis and inhibition of inflammation. These unique properties of APC make it an attractive therapeutic agent to promote the healing of chronic wounds. (WOUND REP REG 2005;13:284-294)
Toxicology Letters, 2008
We write regarding a recent publication in Toxicology Letters:-Regulation of gamma-H2AX and secur... more We write regarding a recent publication in Toxicology Letters:-Regulation of gamma-H2AX and securin contribute to apoptosis by oxaliplatin via a p38 mitogen-activated protein kinase-dependent pathway in human colorectal cancer cells. Toxicology Letters 179 (2008) 63-70, by authors
Radiation Research, 2004
Small cell lung cancer (SCLC) initially responds well to chemotherapy and fractionated radiothera... more Small cell lung cancer (SCLC) initially responds well to chemotherapy and fractionated radiotherapy, but resistance to these treatments eventually develops in the vast majority of cases. To understand how resistance develops in the H69 SCLC cell line, we compared the changes in gene expression associated with 37.5 Gy fractionated X-ray treatment that produced the stable radiation- and drug-resistant H69/R38 cell subline to the changes associated with a single 4- or 8-Gy X-ray treatment. Gene expression was determined by suppression subtractive hybridization combined with Northern blot analysis and two-dimensional (2D) protein electrophoresis. Stable radiation and drug resistance was associated with coordinate changes in the expression of genes of the cytoskeleton, protein synthesis, cell cycle, redox/stress and metabolic pathways. The pattern of these changes was remarkably similar to the changes seen 24 h after a single X-ray treatment of the H69 cells but differed from the changes in expression associated with a single X-ray treatment of the resistant H69/ R38 cells. Stable radiation and drug resistance may be caused by the constitutive expression of those genes transiently expressed by sensitive cells in response to a single X-ray dose. The repeated treatments received during fractionated irradiation may promote the change from a transient to a constitutive pattern of gene expression.
Leukemia Research, 1992
The MTT cell viability assay is widely used in determining drug sensitivity profiles for patients... more The MTT cell viability assay is widely used in determining drug sensitivity profiles for patients with hematological malignancies and in primary screening of potential chemotherapeutic drugs. Because the multidrug resistance (MDR) phenotype is associated with these malignancies, and since many vital dyes are effluxed from MDR expressing cells, we have investigated whether the MDR phenotype interferes with the MTT assay. In CCRF-CEM and K562 human leukemic cell lines and drug-resistant sub-lines developed from them, comparison of the MTT assay with other cell viability assays showed significant variation in IC50 concentrations, although the resistance relative to the sensitive parent cell was correlated. Inclusion of verapamil, an inhibitor of drug efflux activity, had no effect on the MTT assay.
Leukemia Research, 1995
A drug resistant series of sublines were developed by treating the human leukaemia CCRF-CEM cell ... more A drug resistant series of sublines were developed by treating the human leukaemia CCRF-CEM cell line with 16-lOOOng/ml of the anthracycline, epirubicin.
Leukemia Research, 1996
P-glycoprotein- and multidrug resistance-associated protein (MRP)-mediated multidrug resistance i... more P-glycoprotein- and multidrug resistance-associated protein (MRP)-mediated multidrug resistance is associated with decreased drug accumulation. The P-glycoprotein-expressing CCRF-CEM/VLB100 subline and the MRP-expressing CCRF-CEM/E1000 subline are both 50-fold resistant to daunorubicin. However, accumulation of daunorubicin and rhodamine 123 was > 85% reduced in the P-glycoprotein-expressing subline compared to 40-50% in the MRP-expressing subline. Further, the CCRF-CEM/E1000 cells were 30-fold resistant to idarubicin, without reduced accumulation. Verapamil and SDZ PSC 833 restored daunorubicin and rhodamine 123 accumulation, while buthionine sulphoximine affected only the CCRF-CEM/ E1000 subline. We conclude that the verapamil associated change in rhodamine 123 accumulation provides a sensitive functional assay for both P-glycoprotein- and MRP-mediated MDR.
Physics in Medicine and Biology, 2009
In this study we present two prediction methods, mean dose and summed dose, for predicting the nu... more In this study we present two prediction methods, mean dose and summed dose, for predicting the number of A549 cells that will survive after modulated x-ray irradiation. The prediction methods incorporate the dose profile from the modulated x-ray fluence map applied across the cell sample and the linear quadratic (LQ) model. We investigated the clonogenic survival of A549 cells when irradiated using two different modulated x-ray fluence maps. Differences between the measured and predicted surviving fraction were observed for modulated x-ray irradiation. When the x-ray fluence map produced a steep dose gradient across the sample, fewer cells survived in the unirradiated region than expected. When the x-ray fluence map produced a less steep dose gradient across the sample, more cells survived in the unirradiated region than expected. Regardless of the steepness of the dose gradient, more cells survived in the irradiated region than expected for the reference dose range of 1-10 Gy. The change in the cell survival for the unirradiated regions of the two different dose gradients may be an important factor to consider when predicting the number of cells that will survive at the edge of modulated x-ray fields. This investigation provides an improved method of predicting cell survival for modulated x-ray radiation treatment. It highlights the limitations of the LQ model, particularly in its ability to describe the biological response of cells irradiated under these conditions.
Leukemia Research, 2001
Recent reports have correlated multidrug resistance (MDR) and P-glycoprotein expression with decr... more Recent reports have correlated multidrug resistance (MDR) and P-glycoprotein expression with decreased Fas expression and resistance to Fas-mediated apoptosis. We report the MRP-overexpressing MDR subline CEM/E1000 has the same Fas expression (MFI 74.3 90.7) as the parental CCRF-CEM T-cell leukaemia cells (MFI 70.0 93.6; P \ 0.05), and that the level of apoptosis induced by anti-Fas antibody or drug was similar in both cell lines. Further the P-glycoprotein-expressing CEM/VLB 100 subline of the CCRF-CEM cells showed increased Fas expression (MFI 114.8 9 3.6; PB0.001) and no resistance to Fas-mediated apoptosis. This questions the hypothesis that selection of drug resistance results in resistance to Fas-mediated apoptosis, with important implications for the rational use of immunotherapy in the treatment of drug resistant cancer.
International Journal of Cancer, 1998
The H82 "variant" and the H69 "classic" small cell lung cance... more The H82 "variant" and the H69 "classic" small cell lung cancer (SCLC) cell lines were treated with low levels of epirubicin (69 and 14 nM) which caused little cell death but produced the H82/E8 and H69/E8 extended-multidrug resistant sublines. Both were resistant to drugs associated with multidrug resistance (MDR), and to chlorambucil (9.5- and 5.6-fold, respectively) and cisplatin (2.3- and 8.5-fold, respectively). There was increased expression of the multidrug resistance-associated protein (MRP1) in the H82/E8 subline while P-glycoprotein expression was not detected in any cells or sublines. Treatment of the H82 cells for 1 hr with 69 nM epirubicin increased MRP1-mRNA expression within 4 hr and this was associated with an increase in the resistance to epirubicin, chlorambucil, cisplatin and paclitaxel. Further, a 1 hr treatment with non-cytotoxic doses of chlorambucil (2.5 microM), cisplatin (1.3 microM) or paclitaxel (13 nM), drugs not normally associated with MRP1-mediated MDR, also increased MRP1-mRNA expression in the H82 cells with paclitaxel causing the highest increase (4.5-fold). For chlorambucil treatment, this increased MRPI-mRNA expression was accompanied by increased drug resistance while paclitaxel treatment had no effect on drug resistance in the H82 cells. For the drug resistant H82/E8 subline, these drug treatments had no effect on the MRP1-mRNA expression and little effect on increasing the subline drug resistance. However, pretreatment with paclitaxel sensitised the H82/E8 subline to chlorambucil and cisplatin returning the subline to the sensitivity of the H82 cell line. We conclude that treatment with low levels of MDR and non-MDR drugs can induce extended-multidrug resistance in SCLC cells, a process that probably involves the co-ordinate upregulation of MRP1 and other resistance mechanisms. The results also suggest paclitaxel may have a role as a response modifier in the treatment of refractory SCLC.
British Journal of Haematology, 1994
In an attempt to mimic clinical conditions for the treatment of leukaemia, the HL60 promyelocytic... more In an attempt to mimic clinical conditions for the treatment of leukaemia, the HL60 promyelocytic cell line was treated for 18 h with low, clinically relevant, levels of the anthracycline epirubicin and the Vincu alkaloid
British Journal of Haematology, 1999
Relative to the commonly used anthracyclines, little is known about idarubicin and the developmen... more Relative to the commonly used anthracyclines, little is known about idarubicin and the development of multidrug resistance. We have previously shown the K562/IDA subline resulting from intermittent treatment of the K562 human leukaemia cell line with 20 ng/ml idarubicin did not develop multidrug resistance but became more sensitive to etoposide. Additional similar treatments of this subline produced the K562/IDA20 subline which partially retained its etoposide sensitivity although these cells expressed P-glycoprotein and were resistant to paclitaxel. Sensitization to etoposide was associated with increased decatenation activity of topoisomerase II, although there were no changes in topoisomerase IIalpha expression or formation of etoposide-dependent cleavable complexes. In comparison, the K562/IDA10 subline produced by intermittent treatment of the K562 cells, firstly with 5 ng/ml then 10 ng/ml idarubicin, showed no detectable expression of P-glycoprotein, decreased topoisomerase IIalpha expression and increased resistance to etoposide and amsacrine, but not to idarubicin or genistein. Even though intermittent treatment with idarubicin caused increased drug resistance in both sublines, they remained sensitive to idarubicin. Therefore the potential of idarubicin as a substitute for other anthracyclines in the treatment of cancer warrants further investigation.
Biochemical Pharmacology, 1995
With the increasing use of inducers of cellular differentiation in the treatment of leukaemia, it... more With the increasing use of inducers of cellular differentiation in the treatment of leukaemia, it is essential to understand the relationship between differentiation and the expression of the multidrug resistance. Using the K562 human leukaemia cell line and its multidrug resistant subline K562/E15B, differentiation was examined along two different pathways, megakaryocyte in response to treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA), and erythroid in response to treatment with sodium butyrate, in the same cell line. P-glycoprotein expression was increased in the multidrug resistant K562/E15B subline, but not induced in the parental K562 cell line. However, both treatments conferred a different phenotype on the drug resistant subline. TPA treatment caused an increase in P-glycoprotein, increased drug resistance and decreased rhodamine-123 accumulation which was verapamil sensitive, demonstrating that TPA induced a fully functional P-glycoprotein. However, sodium butyrate treatment caused an increase in P-glycoprotein without increased drug resistance or without decreased rhodamine-123 accumulation suggesting that the P-glycoprotein induced by sodium butyrate was nonfunctional. These results stress the importance of examining not only the expression of P-glycoprotein in cells, but also the function of the P-glycoprotein induced.
Near diploid leukemic T-cells (LALW-2), exposed to cytotoxic drugs only as a consequence of thera... more Near diploid leukemic T-cells (LALW-2), exposed to cytotoxic drugs only as a consequence of therapy administered to the donor patient, have been maintained by serial xenograft in nude mice. In comparison with the leukemic line CCRF-CEM, using a growth inhibition assay, LALW- 2 cells were resistant to Vinca alkaloids and actinomycin D (relative resistance, 200-fold or more), were slightly resistant
Platinum and Other Heavy Metal Compounds in Cancer Chemotherapy, 2009
The H69CIS200 and H69OX400 cell lines are novel models of low-level platinum drug resistance deve... more The H69CIS200 and H69OX400 cell lines are novel models of low-level platinum drug resistance developed from H69 human small cell lung cancer cells with eight 4day treatments of 200 ng/ml cisplatin or 400 ng/ml oxaliplatin respectively. A recovery period was given between treatments to emulate the cycles of chemotherapy given in the clinic. The resistant cell lines were approximately 2-fold resistant to cisplatin and oxaliplatin and were cross resistant to both drugs. Platinum resistance was not associated with increased cellular glutathione, decreased accumulation of platinum or increased DNA repair capacity. The H69 platinum sensitive cells entered a lengthy 3 week growth arrest in response to low-level cisplatin or oxaliplatin treatment. This is an example of the coordinated response between the cell cycle and DNA repair. In contrast the H69CIS200 and H69OX400 cells have an alteration in the cell cycle allowing them to rapidly proliferate post drug treatment. The resistant cell lines also have many chromosomal rearrangements most of which are not associated with the resistant phenotype, suggesting an increase in genomic instability in the resistant cell lines. We hypothesised that there was a lack of coordination between the
Cancer chemotherapy and pharmacology, 1997
The effectiveness of N-[2-(dimethylamino)ethyl]acridine-4-carboxamide (DACA) relative to that of ... more The effectiveness of N-[2-(dimethylamino)ethyl]acridine-4-carboxamide (DACA) relative to that of amsacrine, idarubicin, daunorubicin and paclitaxel against three different forms of multidrug resistance (MDR) was determined using two sublines of the CCRF-CEM human leukaemia cell line, the P-glyco-protein-expressing CEM/VLB100 subline and the MRP-expressing CEM/E1000 subline, and two extended-MDR sublines of the HL60 human leukaemia cell line, HL60/E8 and HL60/V8. DACA was effective against P-glycoprotein-mediated MDR and MRP-mediated MDR, whereas the extended-MDR phenotype showed only low levels of resistance (< 2-fold) to DACA. In comparison, idarubicin was ineffective against the MRP and extended-MDR phenotypes. Repeated exposure of the K562 human leukaemia cell line to DACA (55, 546 or 1092 nM for 3 days over 10 weeks) did not result in the development of any significant drug resistance. We conclude that DACA has the potential to treat refractory leukaemia.
Cytometry, 2001
Background: Multidrug resistance (MDR) is mediated by the drug resistance proteins, the multidrug... more Background: Multidrug resistance (MDR) is mediated by the drug resistance proteins, the multidrug resistanceassociated protein (MRP) and P-glycoprotein, both of which confer resistance by the active efflux of chemotherapeutic drugs from the cell. Reduced Fas (CD95/APO-1) expression and resistance to Fas-mediated apoptosis have also been correlated with P-glycoprotein-mediated MDR. Methods: We investigated cell surface Fas expression (using anti-Fas monoclonal antibody DX2.1) in a series of MRP-expressing drug-resistant leukemia sublines, and Pglycoprotein-expressing leukemia sublines, and their susceptibility to apoptosis induced by anti-Fas treatment (CH-11 monoclonal antibody). Caspase-3 activation was detected by Western blot and apoptosis was determined by flow cytometry with 7-aminoactinomycin D (7-AAD) staining of cells.
Platinum and Other Heavy Metal Compounds in Cancer Chemotherapy, 2009
Objective: To examine the pre-clinical and clinical evidence for the use of oxaliplatin or paclit... more Objective: To examine the pre-clinical and clinical evidence for the use of oxaliplatin or paclitaxel salvage chemotherapy in patients with cisplatin-resistant cancer. Methods: Medline was searched for 1) Cell models of acquired resistance reporting cisplatin, oxaliplatin and paclitaxel sensitivities and 2) Clinical trials of single agent oxaliplatin or paclitaxel salvage therapy for cisplatin/carboplatin-resistant ovarian cancer. Results: Oxaliplatin -Oxaliplatin is widely regarded as being active in cisplatin-resistant cancer. In contrast, data in cell models suggests that there is crossresistance between cisplatin and oxaliplatin in cellular models with resistance levels which reflect clinical resistance (<10 fold). Oxaliplatin as a single agent had a poor response rate in patients with cisplatin-resistant ovarian cancer (8%, n=91).
Cancer immunology research, 2014
Induction of antitumor immunity using autologous tumor proteins is an attractive approach to canc... more Induction of antitumor immunity using autologous tumor proteins is an attractive approach to cancer therapy. However, better methods and stimulants to present these autologous proteins back to the immune system are needed. Here, we identify streptavidin as a novel carrier protein and stimulant, and test the efficacy of both syngeneic (rat) and autologous vaccines (dogs) using streptavidin in combination with reduced soluble tumor proteins. Initial syngeneic vaccine studies in the 9L rat glioma model were used to optimize vaccine dose and selectivity. Cytokine and blood analysis was used to monitor the response. Rats receiving two vaccinations of syngeneic tumor vaccine demonstrated a statistically significant (P < 0.05) survival advantage compared with controls (adjuvant only). Notably, vaccination also led to remission rates of between 30% and 60% in the aggressive 9L glioma model. Antibodies to streptavidin were detected in the serum of vaccinated rats; however, antibody levels...
Cytometry, 2001
Recent studies have shown that paclitaxel (Taxol) is an active chemotherapeutic in the treatment ... more Recent studies have shown that paclitaxel (Taxol) is an active chemotherapeutic in the treatment of small cell lung cancer. Paclitaxel binds to tubulin and prevents depolymerization. This causes cells to arrest in the G 2 /M phase of the cell cycle, resulting in sensitization of cells to drug or radiation treatment. Methods: A drug-resistant H69 small cell lung cancer subline was established. Cytotoxicity of cisplatin and chlorambucil was determined using the MTT cell viability assay and distribution of DNA in the cell cycle. DNA distribution was analyzed by flow cytometry after treatment with paclitaxel or the other tubulin-binding drugs, vinblastine and navelbine. Results: The H69-EPR drug-resistant subline was resistant to epirubicin (sixfold) and was cross-resistant to cisplatin (7.5-fold) and chlorambucil (7.5-fold). Pretreatment with paclitaxel or vinblastine, but not navelbine, sensitized the subline to cisplatin and chlorambucil (P Ͻ 0.05), with no effect on parental H69 cells. Sensitization was dose dependent and occurred at doses below those that caused a G 2 /M block in the cell cycle. Conclusion: Sensitization of drug-resistant cells by paclitaxel was not associated with its ability to cause a G 2 /M block in the cell cycle. Sensitization by paclitaxel and vinblastine, but not navelbine, which preferentially targets mitotic tubulin, suggests that sensitization may involve changes in the tubulin-dependent intracellular transport processes rather than changes in mitotic tubulin and the G 2 /M block.
Wound Repair and Regeneration, 2005
Activated protein C (APC) is a serine protease that plays a central role in physiological anticoa... more Activated protein C (APC) is a serine protease that plays a central role in physiological anticoagulation, and has more recently been shown to be a potent anti-inflammatory mediator. Using cultured human cells, we show here that APC up-regulates the angiogenic promoters matrix metalloproteinase-2 in skin fibroblasts and umbilical vein endothelial cells, vascular endothelial growth factor in keratinocytes and fibroblasts, and monocyte chemoattractant protein-1 in fibroblasts. In the chick embryo chorioallantoic membrane assay, APC promoted the granulation/remodeling phases of wound healing by markedly stimulating angiogenesis as well as promoting reepithelialization. In a full-thickness rat skin-healing model, a single topical application of APC enhanced wound healing compared to saline control. APC-treated wounds had markedly more blood vessels on day 7 and a significantly lower infiltration of neutrophils at days 4 and 7. The broad spectrum matrix metallo-proteinas, GM6001, prevented the ability of APC to promote wound healing. In summary, our results show that APC promotes cutaneous wound healing via a complex mechanism involving stimulation of angiogenesis and inhibition of inflammation. These unique properties of APC make it an attractive therapeutic agent to promote the healing of chronic wounds. (WOUND REP REG 2005;13:284-294)
Toxicology Letters, 2008
We write regarding a recent publication in Toxicology Letters:-Regulation of gamma-H2AX and secur... more We write regarding a recent publication in Toxicology Letters:-Regulation of gamma-H2AX and securin contribute to apoptosis by oxaliplatin via a p38 mitogen-activated protein kinase-dependent pathway in human colorectal cancer cells. Toxicology Letters 179 (2008) 63-70, by authors
Radiation Research, 2004
Small cell lung cancer (SCLC) initially responds well to chemotherapy and fractionated radiothera... more Small cell lung cancer (SCLC) initially responds well to chemotherapy and fractionated radiotherapy, but resistance to these treatments eventually develops in the vast majority of cases. To understand how resistance develops in the H69 SCLC cell line, we compared the changes in gene expression associated with 37.5 Gy fractionated X-ray treatment that produced the stable radiation- and drug-resistant H69/R38 cell subline to the changes associated with a single 4- or 8-Gy X-ray treatment. Gene expression was determined by suppression subtractive hybridization combined with Northern blot analysis and two-dimensional (2D) protein electrophoresis. Stable radiation and drug resistance was associated with coordinate changes in the expression of genes of the cytoskeleton, protein synthesis, cell cycle, redox/stress and metabolic pathways. The pattern of these changes was remarkably similar to the changes seen 24 h after a single X-ray treatment of the H69 cells but differed from the changes in expression associated with a single X-ray treatment of the resistant H69/ R38 cells. Stable radiation and drug resistance may be caused by the constitutive expression of those genes transiently expressed by sensitive cells in response to a single X-ray dose. The repeated treatments received during fractionated irradiation may promote the change from a transient to a constitutive pattern of gene expression.
Leukemia Research, 1992
The MTT cell viability assay is widely used in determining drug sensitivity profiles for patients... more The MTT cell viability assay is widely used in determining drug sensitivity profiles for patients with hematological malignancies and in primary screening of potential chemotherapeutic drugs. Because the multidrug resistance (MDR) phenotype is associated with these malignancies, and since many vital dyes are effluxed from MDR expressing cells, we have investigated whether the MDR phenotype interferes with the MTT assay. In CCRF-CEM and K562 human leukemic cell lines and drug-resistant sub-lines developed from them, comparison of the MTT assay with other cell viability assays showed significant variation in IC50 concentrations, although the resistance relative to the sensitive parent cell was correlated. Inclusion of verapamil, an inhibitor of drug efflux activity, had no effect on the MTT assay.
Leukemia Research, 1995
A drug resistant series of sublines were developed by treating the human leukaemia CCRF-CEM cell ... more A drug resistant series of sublines were developed by treating the human leukaemia CCRF-CEM cell line with 16-lOOOng/ml of the anthracycline, epirubicin.
Leukemia Research, 1996
P-glycoprotein- and multidrug resistance-associated protein (MRP)-mediated multidrug resistance i... more P-glycoprotein- and multidrug resistance-associated protein (MRP)-mediated multidrug resistance is associated with decreased drug accumulation. The P-glycoprotein-expressing CCRF-CEM/VLB100 subline and the MRP-expressing CCRF-CEM/E1000 subline are both 50-fold resistant to daunorubicin. However, accumulation of daunorubicin and rhodamine 123 was > 85% reduced in the P-glycoprotein-expressing subline compared to 40-50% in the MRP-expressing subline. Further, the CCRF-CEM/E1000 cells were 30-fold resistant to idarubicin, without reduced accumulation. Verapamil and SDZ PSC 833 restored daunorubicin and rhodamine 123 accumulation, while buthionine sulphoximine affected only the CCRF-CEM/ E1000 subline. We conclude that the verapamil associated change in rhodamine 123 accumulation provides a sensitive functional assay for both P-glycoprotein- and MRP-mediated MDR.