Biomedical subjects

Goli Samimi

Publications and source records attributed to Goli Samimi.

16 recordsLinked to original sources

PubMed2006

Novel mechanisms of platinum drug resistance identified in cells selected for resistance to JM118 the active metabolite of satraplatin.

PURPOSE: The goal of this study was to identify molecular determinants of sensitivity and resistance to JM118, the active metabolite of satraplatin, an orally bioavailable cisplatin analog that has activity in prostate cancer. EXPERIMENTAL DESIGN: Human ovarian carcinoma 2008/JM118 cells were derived from parental 2008 cells by repeated exposure to JM118; the revertant 2008/JM118/REV subline was isolated from the 2008/JM118 cells by growth in the absence of drug. Drug sensitivity was determined by clonogenic assay and Pt levels were measured by ICP-MS. RESULTS: Eight sequential rounds of selection yielded the 2008/JM118 subline that was 4.9-fold resistant to JM118 and cross-resistant at varying levels to satraplatin, cisplatin, carboplatin, and oxaliplatin. Cross-resistance to the other Pt drugs was lost as resistance to JM118 waned. The same parental 2008 cells selected for resistance to cisplatin were partially cross-resistant to JM118. The 2008/JM118 cells accumulated significantly more Pt than the 2008 cells when exposed to low concentrations of either JM118 or cisplatin indicating a detoxification process that involves intracellular sequestration. In contrast, 2008 cells selected for cisplatin resistance accumulated less cisplatin and less JM118 reflecting a mechanism involving reduced accumulation. The 2008 and 2008/JM118 cells did not differ in their uptake or efflux of 64Cu, expression of Cu efflux transporters ATP7A or ATP7B or their glutathione content. The 2008/JM118 cells exhibited 3.0-7.7-fold hypersensitivity to docetaxel, paclitaxel and doxorubicin. Expression profiling identified 4 genes that were significantly up-regulated and 19 that were down-regulated in the 2008/JM118 cells at a false discovery rate of 1 gene. CONCLUSIONS: While the cellular defense mechanisms that protect cells against JM118 also mediate resistance to the other Pt drugs, these mechanisms are quite different from those commonly found in cells selected for resistance to cisplatin. JM118-resistant cells accumulate more rather than less Pt and rely on an intracellular detoxification mechanism different from that involved in cisplatin resistance. This is consistent with clinical evidence suggesting that satraplatin has activity in diseases in which cisplatin does not. In this model, JM118 resistance is associated with substantial collateral hypersensitivity to docetaxel, paclitaxel, and doxorubicin.

Antineoplastic Agents↗

PubMed2006

Identification of genes whose expression is associated with cisplatin resistance in human ovarian carcinoma cells.

The goal of this study was to identify genes consistently differentially expressed in multiple pairs of isogenic cisplatin (DDP)-sensitive and resistant human ovarian carcinoma cell lines using microarray-based expression profiling. Expression profiling was carried out on six pairs of ovarian carcinoma cells lines growing under identical conditions; each cell expression profile was independently replicated six times. No genes were differentially expressed in all six pairs of cells or even in even in any five of the six pairs. Eighteen genes and 1 EST were upregulated, and four genes and 1 EST were downregulated, in at least four cell pairs. Of these, only metallothionein 2A has previously been implicated in DDP resistance. Among the genes identified on the basis of six replicates, an average of 24.8% would have been missed if only five replicates had been performed, and 38.3% would have been missed with only four replicates. The genes did not identify a dominant biochemical pathway or ontology category as being linked to DDP resistance; however, hierarchical clustering provided evidence for two classes DDP-resistant phenotypes within which there are additional cell pair-specific alterations. Many of the genes identified in this study play important roles in cell surface interactions and trafficking pathways not previously linked to DDP resistance. The genes discovered by this extensively replicated analysis are candidates for prediction of DDP responsiveness in ovarian cancer patients.

Antineoplastic Agents↗

PubMed2005

Modulation of the cellular pharmacology of JM118, the major metabolite of satraplatin, by copper influx and efflux transporters.

Satraplatin is an orally bioavailable platinum analog that has activity in prostate cancer. JM118 is the most abundant species found in the plasma following the oral ingestion of satraplatin and has anti-tumor activity in vitro against cell lines that are resistant to cisplatin (DDP). The goal of the current study was to determine whether the activity of JM118 in some DDP-resistant cells can be explained by differences in the cellular pharmacology of the two drugs. The effect of each of the Cu transporters CTR1, ATP7A and ATP7B on sensitivity to the growth inhibitory effect of JM118 and its cellular pharmacology was examined to identify the characteristics of JM118 that distinguish it from DDP. These studies were performed using wild type and CTR1-/- homozygous knockout mouse embryo cells, and human Me32a Menkes disease fibroblasts that do not express either ATP7A or ATP7B plus sublines molecularly engineered to express either ATP7A (MeMNK cells) or ATP7B (MeWND cells). Knockout of the Cu influx transporter CTR1 in murine embryo cells increased their resistance to DDP and reduced its cellular accumulation but had no effect on sensitivity to JM118 or its uptake. In the case of DDP, forced expression of either of the two Cu efflux transporters, ATP7A or ATP7B, in Me32a cells rendered them resistant to DDP, increased whole cell accumulation of Pt but reduced the amount of Pt in DNA. In the case of JM118, forced expression of either ATP7A or ATP7B rendered Me32a cells resistant, increased not only whole cell Pt accumulation but also increased rather than decreased the amount of Pt in DNA. These results demonstrate that both ATP7A and ATP7B mediate resistance to JM118 as well as DDP and suggest that they sequester both DDP and JM118 into vesicular compartments within the cell resulting in enhanced whole cell accumulation and reduced cytotoxicity. We conclude that there are two important differences between DDP and JM118 with respect to the effect of Cu transporters on their cellular pharmacology. First, whereas CTR1 is involved in DDP accumulation it does not play a role in the uptake of JM118. Second, ATP7A and ATP7B, while they both mediate resistance, have opposite effects on the accumulation of Pt in DNA following exposure to the two drugs. ATP7A and ATP7B appear to be able to modulate the toxicity of the Pt that accumulates in DNA following exposure to JM118. These results suggest that JM118 will retain activity in cells in which DDP resistance is due to the loss of CTR1, but not in cells in which resistance is due to enhanced expression of ATP7A or ATP7B.

Animals↗

PubMed2005

Intracellular localization and trafficking of fluorescein-labeled cisplatin in human ovarian carcinoma cells.

PURPOSE: We sought to identify the subcellular compartments in which cisplatin [cis-diamminedichloroplatinum (DDP)] accumulates in human ovarian carcinoma cells and define its export pathways. EXPERIMENTAL DESIGN: Deconvoluting digital microscopy was used to identify the subcellular location of fluorescein-labeled DDP (F-DDP) in 2008 ovarian carcinoma cells stained with organelle-specific markers. Drugs that block vesicle movement were used to map the traffic pattern. RESULTS: F-DDP accumulated in vesicles and were not detectable in the cytoplasm. F-DDP accumulated in the Golgi, in vesicles belonging to the secretory export pathway, and in lysosomes but not in early endosomes. F-DDP extensively colocalized with vesicles expressing the copper efflux protein, ATP7A, whose expression modulates the cellular pharmacology of DDP. Inhibition of vesicle trafficking with brefeldin A, wortmannin, or H89 increased the F-DDP content of vesicles associated with the pre-Golgi compartments and blocked the loading of F-DDP into vesicles of the secretory pathway. The importance of the secretory pathway was confirmed by showing that wortmannin and H89 increased whole cell accumulation of native DDP. CONCLUSIONS: F-DDP is extensively sequestered into vesicular structures of the lysosomal, Golgi, and secretory compartments. Much of the distribution to other compartments occurs via vesicle trafficking. F-DDP detection in the vesicles of the secretory pathway is consistent with a major role for this pathway in the efflux of F-DDP and DDP from the cell.

Adenosine Triphosphatases↗

PubMed2004

cDNA microarray-based identification of genes and pathways associated with oxaliplatin resistance.

In order to identify genes whose expression is associated with resistance to the chemotherapeutic agent oxaliplatin, transcripts differentially expressed between an oxaliplatin sensitive and a stably resistant subline were compared in six independent replicates using Stanford cDNA microarrays for five cell lines. "Significance analysis of microarrays" (SAM) was used to identify genes whose expression was statistically significantly different in the sensitive versus resistant members of each cell line pair. The biochemical pathways of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database were searched to identify those pathways in which the number of SAM-identified genes exceeded the number expected. This identified four pathways in which upregulated genes were significantly associated with resistance in two of the cell line pairs, and two pathways in which the association was found in three cell line pairs. The search also identified 12 pathways in which downregulated genes were associated with resistance in two cell line pairs and one pathway in which the association reached statistical significance in three cell line pairs. Pathways identified included the ribosome pathway, the Huntington's disease pathway that includes caspase 8, and the ATP synthesis pathways. Determination of the chromosomal location of each SAM-identified gene revealed several locales within which genes lay in close proximity, including three genes (APACD, IF-2, and REV1L) located on chromosome 2 that lie immediately adjacent to each other and were significantly upregulated in three of five cell line pairs. Biochemical pathway and chromosomal mapping of genes identified by SAM as differentially expressed in related cell line pairs points to mechanisms and chromosomal sites not previously suspected of association with the oxaliplatin-resistant phenotype.

Adenosine Triphosphate↗

PubMed2004

Increased expression of the copper efflux transporter ATP7A mediates resistance to cisplatin, carboplatin, and oxaliplatin in ovarian cancer cells.

PURPOSE: The goal of this study was to determine the effect of small changes in ATP7A expression on the pharmacodynamics of cisplatin, carboplatin, and oxaliplatin in human ovarian carcinoma cells. EXPERIMENTAL DESIGN: Drug sensitivity and cellular pharmacology parameters were determined in human 2008 ovarian carcinoma cells and a subline transfected with an ATP7A-expression vector ATP7A (2008/MNK). Drug sensitivity was determined by clonogenic assay, platinum (Pt) levels were measured by inductively coupled plasma mass spectroscopy, copper (Cu) accumulation was quantified with (64)Cu, and the subcellular distribution of ATP7A was assessed by confocal digital microscopy. RESULTS: The 1.5-fold higher expression of ATP7A in the 2008/MNK cells was sufficient to alter Cu cellular pharmacokinetics but not confer Cu resistance. In contrast, it was sufficient to render the 2008/MNK cells resistant to cisplatin, carboplatin, and oxaliplatin. Resistance was associated with increased rather than decreased whole-cell Pt drug accumulation and increased sequestration of Pt into the vesicular fraction. Cu triggered relocalization of ATP7A away from the perinuclear region, whereas at equitoxic concentrations the Pt drugs did not. CONCLUSIONS: A small increase in ATP7A expression produced resistance to all three of the clinically available Pt drugs. Whereas increased expression of ATP7A reduced Cu accumulation, it did not reduce accumulation of the Pt drugs. Under conditions where Cu triggered ATP7A relocalization, the Pt drugs did not. Thus, although ATP7A is an important determinant of sensitivity to the Pt drugs, there are substantial differences between Cu and the Pt drugs with respect to how they interact with ATP7A and the mechanism by which ATP7A protects the cell.

Adenosine Triphosphatases↗

PubMed2004

Confocal microscopic analysis of the interaction between cisplatin and the copper transporter ATP7B in human ovarian carcinoma cells.

Some cisplatin (DDP)-resistant cells overexpress the copper export transporter ATP7B, and cells molecularly engineered to overexpress ATP7B are resistant to DDP. The interaction of Cu with ATP7B normally triggers its relocalization from the perinuclear region to more peripheral vesicles. To investigate the interaction of DDP with ATP7B, we examined the effect of DDP on the subcellular localization of ATP7B using human ovarian carcinoma cells expressing a cyan fluorescent protein (ECFP)-tagged ATP7B (2008/ECFP-ATP7B). ATP7B expression was confirmed in 2008/ECFP-ATP7B cells by Western blotting, and its functionality was documented by showing that it rendered the cells 1.9-fold resistant to CuSO(4) and 4.1-fold resistant to DDP and also reduced the accumulation of both drugs. There was greater sequestration of Pt into intracellular vesicles in the 2008/ECFP-ATP7B cells than in the 2008/ECFP cells. Confocal digital microscopy revealed that ECFP-ATP7B localized in the perinuclear region in absence of drug exposure and that both Cu and DDP triggered relocalization to more peripheral vesicular structures. A fluorescein-labeled form of DDP that retained cytotoxicity and was subject to the same mechanisms of resistance as DDP colocalized with ECFP-ATP7B in the 2008/ECFP-ATP7B cells, whereas the same fluorochrome lacking the DDP moiety did not. These results provide evidence that DDP directly interacts with ATP7B to trigger its relocalization and that ATP7B mediates resistance to DDP by sequestering it into vesicles of the secretory pathway for export from the cell.

Adenosine Triphosphatases↗

PubMed2004

The copper influx transporter human copper transport protein 1 regulates the uptake of cisplatin in human ovarian carcinoma cells.

Cells selected for resistance to cisplatin are often cross-resistant to copper and vice versa, and the major copper influx transporter copper transport protein 1 (CTR1) has been shown to regulate the uptake of cisplatin, carboplatin, and oxaliplatin in yeast. To further define the role of hCTR1 in human tumor cells, the ovarian carcinoma cell line A2780 was molecularly engineered to increase expression of hCTR1 by a factor of 20-fold. Enhanced expression of hCTR1 in the A2780/hCTR1 cells was associated with a 6.5-fold increase in basal steady-state copper content and a 13.7-fold increase in initial copper influx, demonstrating that the exogenously expressed hCTR1 was functional in altering copper homeostasis. The A2780/hCTR1 cells accumulated 46% more platinum after a 1-h exposure to 2 microM cisplatin, and 55% more after a 24 h exposure, than the control A2780/empty vector cells. The initial uptake of cisplatin was 81% higher in the A2780/hCTR1 cells when measured at 5 min. Thus, increased expression of hCTR1 had a substantially larger effect on the cellular pharmacology of copper than cisplatin. Interestingly, the increased uptake of copper and cisplatin was accompanied by only a marginal increase in sensitivity to the cytotoxic effect of copper and cisplatin, and there was no increase in the extent of cisplatin-DNA adduct formation. Thus, although increased expression of hCTR1 mediates greater cellular accumulation of copper and cisplatin, hCTR1 delivers these compounds into intracellular compartments from which they do not have ready access to their key cytotoxic targets.

Antineoplastic Agents↗

PubMed2004

The role of copper transporters in the development of resistance to Pt drugs.

Recent studies in yeast, mouse and human cells suggest that the conserved metal binding transporters of the Cu homeostasis pathway can mediate resistance to Pt drugs in cancer cells. This review summarizes the data available from these studies. The observation that cells selected for resistance to Cu or the Pt drugs display bidirectional cross-resistance, parallel defects in the transport of Cu and the Pt drugs and altered expression of Cu transporters is consistent with the concept that the Cu homeostasis proteins regulate sensitivity to the Pt drugs by influencing their uptake, efflux and intracellular distribution. This model is supported by the finding that when mammalian and yeast cells are genetically engineered to express altered levels of the Cu transporters they exhibit altered sensitivity to Pt drugs and are defective in intracellular Pt accumulation due to altered uptake and/or efflux rates. Negative associations between the expression of ATP7A and ATP7B and the outcome of Pt therapy further support the significance of the Cu homeostasis proteins as both markers of and contributors to Pt resistance.

Animals↗

PubMed2004

Modulation of the cellular pharmacology of cisplatin and its analogs by the copper exporters ATP7A and ATP7B.

The copper efflux transporters ATP7A and ATP7B sequester intracellular copper into the vesicular secretory pathway for export from the cell. The influence of these transporters on the pharmacodynamics of cisplatin, carboplatin, and oxaliplatin was investigated using human Menkes' disease fibroblasts (Me32a) that do not express either transporter and sublines molecularly engineered to express either ATP7A (MeMNK) or ATP7B (MeWND). Cellular copper levels were significantly higher in the Me32a cells than in the MeMNK and MeWND sublines. These transporter-proficient sublines were resistant to the cytotoxic effect of copper, cisplatin, and carboplatin but were hypersensitive to oxaliplatin. Whole-cell accumulation of platinum after a 24-h exposure was significantly increased in the MeMNK and MeWND cells for all three platinum drugs, but this was accompanied by an increase in the amount of platinum reaching the DNA only for oxaliplatin. Vesicles isolated from MeMNK cells contained more platinum after exposure to cisplatin and carboplatin, whereas the platinum content of vesicles from MeWND cells was increased after exposure to all three drugs. Although copper triggered relocalization of ATP7A from the perinuclear region to more peripheral locations, the platinum drugs did not. These results demonstrate that both ATP7A and ATP7B modulate the pharmacodynamics of all three clinically used platinum drugs. The data are consistent with the hypothesis that these copper exporters sequester the platinum drugs into subcellular compartments, limiting their cytotoxicity, similar to their effect on copper. However, in this model system, although copper is readily exported after vesicular sequestration, the platinum drugs are not.

Adenosine Triphosphatases↗

PubMed2003

Increase in expression of the copper transporter ATP7A during platinum drug-based treatment is associated with poor survival in ovarian cancer patients.

PURPOSE: The Cu efflux transporter ATP7A is overexpressed in some cisplatin-resistant ovarian carcinoma cell lines. We examined the expression of ATP7A in the major normal human organs and in several types of human malignancies and sought to determine whether ATP7A expression changed during treatment of ovarian carcinomas with Pt-containing regimens. EXPERIMENTAL DESIGN: ATP7A expression was quantified by immunohistochemical staining using microarrays containing normal and malignant tissues, and standard sections of 54 paired tumor samples obtained from ovarian carcinoma patients before and after at least two cycles of platinum-based therapy. RESULTS: ATP7A was expressed in normal endometrium, prostate, testis, and kidney but was not detected in the other major organs. ATP7A was expressed in some of the most common human malignancies, including prostate (7 of 7), breast (10 of 10), lung (8 of 8), colon (5 of 8), and ovary (6 of 7), as well as in a wide variety of other types of malignancy. ATP7A staining was detected in 28 of 54 ovarian carcinomas before treatment. Patients with increased ATP7A expression after treatment (18 of 54) exhibited poorer actuarial survival (P<0.0057 by log-rank test). Expression of ATP7A either before or after treatment was not associated with other clinical factors. CONCLUSIONS: Although ATP7A is not detectable in most normal tissues it is expressed in a considerable fraction of many common tumor types. Enrichment of the tumor for ATP7A-expressing cells during platinum drug-based treatment of ovarian cancers is associated with poor survival. These findings are in agreement with results of in vitro studies from this laboratory demonstrating that increased expression of ATP7A renders cells resistant to cisplatin and carboplatin.

Adenosine Triphosphatases↗

PubMed2003

Cross-resistance to cisplatin in cells with acquired resistance to copper.

PURPOSE: Cells selected for resistance to cisplatin (DDP) demonstrate cross-resistance to copper (Cu) suggesting one or more common mechanisms of cellular defense. We sought to determine whether cells selected for resistance to Cu are cross-resistant to DDP. MATERIALS AND METHODS: Parental HuH7 human hepatoma cells and the CuR27 Cu-resistant subline were compared for sensitivity to Cu and DDP by clonogenic assay, and with respect to drug uptake and efflux by measuring cellular Cu and Pt content. RESULTS: CuR27 cells were found to be 1.8-fold resistant to Cu and 8.6-fold cross-resistant to DDP. Changes in the cellular pharmacokinetics of Cu in the CuR27 cells were paralleled by changes in the kinetics of DDP. The accumulations of Cu and DDP measured at 1 min were, respectively, 36% and 26% of those in the parental HuH7 cells. The initial rate of efflux from the CuR27 cells was 6.2-fold faster for Cu and 2.5-fold faster for DDP than from the HuH7 cells. Cu reduced the accumulation of DDP in the HuH7 cells in a concentration-dependent manner and vice versa. DDP also reduced the efflux of Cu. Western blot analysis demonstrated that expression of the Cu exporter ATP7B was increased 3.9-fold in the CuR27 cells. CONCLUSIONS: In this model system, cross-resistance between Cu and DDP was bidirectional and accompanied by parallel changes in the cellular pharmacokinetics of both compounds. The results are consistent with the idea that transporters and chaperones that normally mediate Cu homeostasis also directly or indirectly modulate the accumulation of DDP.

Adenosine Triphosphatases↗

PubMed2003

The copper export pump ATP7B modulates the cellular pharmacology of carboplatin in ovarian carcinoma cells.

Human tumor cells lines with acquired resistance to cisplatin (DDP) and carboplatin (CBDCA) are often cross-resistant to copper and vice versa, and some DDP-resistant cells overexpress the copper export pump ATP7B. We sought to demonstrate that ATP7B directly mediates resistance to DDP and CBDCA by stably transfecting human carcinoma cells with a vector designed to express ATP7B. Increased expression of ATP7B rendered all three cell lines tested more resistant to a 1-h exposure to DDP (1.6-2.6-fold), CBDCA (1.5-1.6-fold), and copper (1.2-1.4-fold). The effect of ATP7B on the cellular pharmacology of 64Cu and [14C]CBDCA was investigated in more detail using one cell pair (2008 cells transfected with an empty vector or an ATP7B-expressing vector). In the 2008/ATP7B subline, steady-state copper levels were decreased under both basal and copper-supplemented conditions, as was steady-state CBDCA content upon exposure to 50 microM [14C]CBDCA. Over the first 5 min, the average rate of accumulation of copper and CBCDA in the 2008/ATP7B cells was reduced by 37 and 61%, respectively. Efflux was more rapid from 2008/ATP7B cells for both copper and CBDCA. Two-compartment modeling indicated that the second phase of efflux was increased by a factor of 3.9-fold for CBCDA and to an even greater extent for copper. We conclude that expression of ATP7B regulates sensitivity to CBDCA as well as to DDP and copper and that a transporter that normally mediates copper homeostasis modulates the cellular pharmacology of CBDCA.

Adenosine Triphosphatases↗

PubMed2002

Acquisition of resistance to cisplatin is accompanied by changes in the cellular pharmacology of copper.

Impaired uptake of cisplatin (DDP) consistently accompanies the acquisition of resistance to the platinum drugs. The pathways by which DDP enters or exits from cells remain poorly defined. Using three pairs of human ovarian carcinoma cell lines, each consisting of a sensitive parental line and a stably DDP-resistant subline derived by in vitro selection, resistance to DDP was found to be accompanied by cross-resistance to Cu. Accumulation of DDP in the resistant sublines ranged from 38 to 67% of that in the parental line at 1 h, and DNA adduct formation varied from 10 to 38% of that in the sensitive cells. The DDP-resistant cells had 22-56% lower basal levels of copper, and the copper levels were only 27-46% of those observed in the sensitive parental lines after a 24-h exposure to medium supplemented with copper. The initial influx rate for DDP in the three resistant cell lines ranged from 23 to 55% of that in the sensitive cells of each pair; the initial influx rate for copper in the resistant cells varied from 56 to 75% of control. Studies performed using one pair of cell lines demonstrated that for both copper and DDP the initial efflux rate was lower, whereas the terminal efflux rate was higher in the resistant cells. On Western blot analysis all three resistant lines exhibited increased expression of one or the other of the two copper export pumps (ATP7A or ATP7B) with no change in the HAH1 chaperone. We conclude that the acquisition of DDP resistance in ovarian carcinoma is accompanied by alterations in the cellular pharmacology of DDP that are paralleled by similar changes in the uptake and efflux of copper. These results are consistent with the concept that DDP enters and exits from the cell via transporters that normally mediate copper homeostasis.

Adenosine Triphosphatases↗

PubMed2002

Retroviral expression of a kinase-defective IGF-I receptor suppresses growth and causes apoptosis of CHO and U87 cells in-vivo.

BACKGROUND: Phosphatidylinositol-3,4,5-triphosphate (PtdInsP3) signaling is elevated in many tumors due to loss of the tumor suppressor PTEN, and leads to constitutive activation of Akt, a kinase involved in cell survival. Reintroduction of PTEN in cells suppresses transformation and tumorigenicity. While this approach works in-vitro, it may prove difficult to achieve in-vivo. In this study, we investigated whether inhibition of growth factor signaling would have the same effect as re-expression of PTEN. METHODS: Dominant negative IGF-I receptors were expressed in CHO and U87 cells by retroviral infection. Cell proliferation, transformation and tumor formation in athymic nude mice were assessed. RESULTS: Inhibition of IGF-IR signaling in a CHO cell model system by expression of a kinase-defective IGF-IR impairs proliferation, transformation and tumor growth. Reduction in tumor growth is associated with an increase in apoptosis in-vivo. The dominant-negative IGF-IRs also prevented growth of U87 PTEN-negative glioblastoma cells when injected into nude mice. Injection of an IGF-IR blocking antibody alphaIR3 into mice harboring parental U87 tumors inhibits tumor growth and increases apoptosis. CONCLUSION: Inhibition of an upstream growth factor signal prevents tumor growth of the U87 PTEN-deficient glioma to the same extent as re-introduction of PTEN. This result suggests that growth factor receptor inhibition may be an effective alternative therapy for PTEN-deficient tumors.

Animals↗

PubMed2002

Using mRNA expression profiling to determine anticancer drug efficacy.

Pharmacogenomics is a fast-growing field of investigations that aims to further elucidate the inherited nature of interindividual differences in drug disposition and effects, with the ultimate goal of providing a stronger scientific basis for selecting the optimal drug therapy. Providing the right drug for the right patient is an important problem in the treatment of cancer. This is mainly due to the lack of information about the sensitivity of the tumor for a specific treatment modality, such as either chemotherapy or radiation treatment. This presentation highlights two approaches to identify responsiveness to treatment. Both approaches are based on the identification of expression profiles. The first approach concentrates on drug resistance and the second on the signaling pathways leading up to the death of the cell. Both approaches provide expression profiles; however, the more dynamic expression profiling as used to determine the signaling in damage cells promises to be a better determinant for the pharmacogenomic changes in expression profiles and, consequently, a potential better determinant for drug efficacy.

Antineoplastic Agents↗