Ovarian cancer: strategies for overcoming resistance to chemotherapy

Insulin-like growth factor receptor I targeting in epithelial ovarian cancer

OBJECTIVES

Preclinical evaluation of the anti-neoplastic activity of an insulin-like growth factor I receptor (IGF-IR) kinase inhibitor in ovarian cancer.

METHODS

The OVCAR-3 and OVCAR-4 cell lines were investigated under serum-free tissue culture conditions. IGF-I and IGF-II production were evaluated by standard ELISA and immunohistochemistry. IGF-IR expression and protein levels were evaluated by Western blotting. Cytotoxicity assays were performed in triplicates using the Alamar colorimetric assay. Apoptosis was evaluated by flow cytometry and by Western blotting for PARP.

RESULTS

The OVCAR-3 and OVCAR-4 cell lines produce IGF-I and IGF-II, and express IGF-IR, detectable by Western blotting, supporting the existence of an autocrine loop. The existence of this loop justified studies of NVP-AEW541, a small molecular weight inhibitor of the IGF-IR kinase. We observed growth inhibition of the ovarian cancer cell lines, with IC50 between 5 and 15 microM. We also observed that NVP-AEW541 sensitized cells to cisplatin in vitro. Western blotting demonstrated that NVP-AEW541 induced apoptosis at the concentrations that were used in the cytotoxicity assays, and decreased the concentration of the phosphorylated AKT signaling protein downstream of the IGF-IR.

CONCLUSIONS

IGF-IR is a potential new molecular target in ovarian cancer. The anti-neoplastic activity of NVP-AEW541 in ovarian cancer was observed at concentrations higher than those previously reported for multiple myeloma, suggesting the possibility that a portion of the observed anti-neoplastic activity could involve targets other than the IGF-IR. Experiments are being conducted to investigate the cytotoxicity profile in vivo and the clinical relevance of NVP-AEW541 in ovarian cancer treatment.

GBP1 overexpression is associated with a paclitaxel resistance phenotype

In the search for novel genes involved in the paclitaxel resistance phenotype, prior studies of gene expression in paclitaxel-resistant cell lines and their paired drug-sensitive parental lines using high-density Affymetrix GeneChip arrays identified guanylate-binding protein 1 (GBP1) gene as an overexpressed transcript. The GBP1 gene encodes a large GTPase that is induced by interferon gamma (IFN-gamma) in a variety of eukaryotic cells. In this report we characterize GBP1 and demonstrate that GBP1 expression is consistently upregulated in 7 of 8 paclitaxel or doxorubicin-resistant human cancer cell lines as compared to its expression in the relevant drug-sensitive parental lines. Analysis of GBP1 expression using the Cancer Profiling Array showed that GBP1 is ubiquitously expressed with no significant difference in expression levels between normal and tumor tissue. Parallel analysis of the Cancer Cell Line Profiling Array determined that GBP1 expression in a majority of cell lines derived from human tumors of different tissue origin was induced to variable levels following exposure to multiple stress agents including paclitaxel and doxorubicin. Importantly, stable expression of a GBP1 transgene in the paclitaxel-sensitive ovarian cancer cell line OVCAR8 was sufficient to confer moderate paclitaxel resistance. Our data suggest that increased expression of the GBP1 gene may play an important role in the development of multi-drug resistance (MDR).

Gene expression profiles associated with response to chemotherapy in epithelial ovarian cancers

PURPOSE

The goal of this study was to determine whether distinct gene expression profiles are associated with intrinsic and/or acquired chemoresistance in epithelial ovarian carcinoma.

EXPERIMENTAL DESIGN

Gene expression profiles were generated from 21 primary chemosensitive tumors and 24 primary chemo-resistant tumors using cDNA-based microarrays. Gene expression profiles of both groups of primary tumors were then compared with those of 15 ovarian carcinomas obtained following platinum-based chemotherapy ("post-chemotherapy" tumors). A theme discovery tool was used to identify functional categories of genes involved in drug resistance.

RESULTS

Comparison of primary chemosensitive and chemo-resistant tumors revealed differential expression of 85 genes (P < 0.001). Comparison of gene expression profiles of primary chemosensitive tumors and post-chemotherapy tumors revealed more robust differences with 760 genes differentiating the two groups (P < 0.001). In contrast, only 230 genes were differentially expressed between primary chemo-resistant and post-chemotherapy groups (P < 0.001). Common to both gene lists were 178 genes representing transcripts differentially expressed between post-chemotherapy tumors and all primary tumors irrespective of intrinsic chemosensitivity. The gene expression profile of post-chemotherapy tumors compared with that of primary tumors revealed statistically significant overrepresentation of genes encoding extracellular matrix-related proteins.

CONCLUSIONS

These data show that gene expression profiling can discriminate primary chemo-resistant from primary chemosensitive ovarian cancers. Gene expression profiles were also identified that correlate with states of intrinsic and acquired chemoresistance and that represent targets for future investigation and potential therapeutic interventions.

Drug resistance in ovarian cancer: The emerging importance of gene transcription and spatio-temporal regulation of resistance

Resistance to carboplatin plus paclitaxel, one of the most active drug combinations in ovarian cancer, is the major barrier to the successful long-term treatment of this disease. Understanding the mechanisms involved is a first step towards rational strategies to overcome drug resistance and is an area of intense research effort. Recent work has identified several gene families which appear to contribute to the evolution of drug resistance and which are involved in regulating DNA damage, apoptosis and survival signalling. These genes may be co-ordinately regulated as part of a gene expression program that confers drug resistance through multiple pathways. The subcellular localisation of the gene products and their kinetic regulation following exposure to chemotherapeutic agents may also play a part in the development of drug resistance. This provides a more complex paradigm for drug resistance in which the steady-state expression of a single gene may not be predictive of response to therapy. Nevertheless, the identification of critical genes, most relevant to the development of clinical drug resistance, is now feasible through microarray analysis of tumour samples, and strategies aimed at the circumvention of resistance can be developed using these data.

New drugs in cancer therapy, National Tumor Institute, Naples, 17-18 June 2004

An international meeting on 'New Drugs in Cancer Therapy' was held at the National Tumor Institute of Naples, on 17-18 June 2004. The first session of the meeting focused on analogs of conventional anti-cancer drugs, such as taxanes, platinum compounds, anthracyclines and topoisomerase I inhibitors. The data of a phase II trial of BMS-247550, an epothilone B analog, in patients with renal cell carcinoma were reported. Data were also presented on BBR-3464, a trinucleate platinum analog which was developed on the grounds of greater potency, a more rapid rate of DNA binding and the ability to induce apoptosis regardless of the p53 status of the cell. Pegylated-coated liposomal formulation doxorubicin (Caelyx) has shown efficacy in metastatic breast cancer and in advanced ovarian cancer; sabarubicin is a third-generation anthracycline with equal or superior potency to doxorubicin or idarubicin in a variety of human tumor cell lines of different histotypes. The main mechanisms of resistance to topoisomerase I inhibitors were discussed; data on diflomotecan were reported, showing a narrow therapeutic index of the drug. The second session of the meeting focused on the ErbB family as a target for anti-cancer therapy. Recent evidence of a correlation between epidermal growth factor receptor (EGFR) mutations at exons 18-21 and clinical response of advanced non-small cell lung cancer to gefitinib therapy was commented on. The issue of the association between ErbB2 expression and gefitinib activity was addressed, while clinical data of a phase II study of gefitinib in advanced breast cancer were presented. Monoclonal antibodies targeting EGFR represent another worthwhile way to interfere with EGFR-driven signal transduction. Cetuximab is reaching market registration in advanced colorectal cancer; in particular, due to the results of the BOND study. The recently presented results of the Bonner study strongly support the activity of this drug in head and neck cancer. A step forward in the research on anti-EGFR monoclonal antibodies may be represented by humanized monoclonal antibodies, such as EMD 72000 and ABX-EGF. Imatinib mesylate is probably the most outstanding example of an effective targeted therapy--its activity in gastrointestinal stromal tumors was so exciting that the drug reached the market without undergoing phase III evaluation. The third session of the meeting was on angiogenesis inhibitors. Drugs may interfere with the angiogenic process via different mechanisms and there is a sound rationale for combining anti-angiogenic agents with chemotherapy or multiple anti-angiogenic strategies. Clinical results obtained with direct anti-angiogenic agents have been negative up to now, but some exciting results have been seen with bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor (VEGF). A few VEGF-tyrosine kinase inhibiting small molecules, such as ZD6474, AZD2171 and PTK/ZK, are undergoing clinical trials. The fourth session of the meeting was on interference with intracellular signal transduction. Farnesyl transferase inhibitors exert their action by interfering with either pro-Ras or RhoB farnesylation. Several clinical studies of different phases with compounds belonging to this class have been carried out, either alone or in combination with chemotherapy; unfortunately, all of them have turned out to be negative. Cell cycle inhibitors, such as CYC-202 and BMS-387032, represent a class of interesting compounds which are in the early phase of development and whose clinical results are eagerly awaited. Another strategy to achieve cell cycle inhibition is to target heat shock protein 90, a molecular chaperone required for protein folding. Clinical data on depsipeptide, a histone deacetylase (HDAC) inhibitor with activity in T cell lymphoma, were presented. Suberoylanilide hydroxamic acid is another small molecular weight inhibitor of HDAC activity. Phase I/II clinical trials have shown low toxicity and evidence of anti-tumor activity; on the other hand, this compound has potential for synergism with radiotherapy, chemotherapy and biologicals.

No significant role for beta tubulin mutations and mismatch repair defects in ovarian cancer resistance to paclitaxel/cisplatin

Background

The mechanisms of chemoresistance in ovarian cancer patients remain largely to be elucidated. Paclitaxel/cisplatin combination is the standard chemotherapeutic treatment for this disease, although some patients do not respond to therapy. Our goals were to investigate whether TUBB mutations and mismatch repair defects underlie paclitaxel and cisplatin resistance.

Methods

Thirty-four patients with primary ovarian carcinomas (26 serous and eight clear cell carcinomas) treated with paclitaxel/cisplatin were analysed. TUBB exon 4 was analysed by nested PCR after a first round PCR using intronic primers. Microsatellite analysis was performed with the quasimonomorphic markers BAT 26 and BAT 34.

Results

Twenty-two of the 34 ovarian cancers (64.7%) presented residual tumour after surgery, seven of which (7/22; 31.8%) were shown to be chemoresistant (five serous and two clear cell tumours). Sequence analysis did not find any mutation in TUBB exon 4. Microsatellite instability was not detected in any of the ovarian carcinomas.

Conclusion

We conclude that TUBB exon 4 mutations and mismatch repair defects do not play a significant role in paclitaxel/cisplatin resistance.

Prolactin inhibits apoptosis of ovarian carcinoma cells induced by serum starvation or cisplatin treatment

Prolactin, a peptide hormone essential for the development and function of reproductive organs, is involved in development of breast, prostate and colorectal cancers. However, the role of prolactin on the carcinogenesis of ovarian carcinomas is unclear. In this study, we show that mRNA of prolactin receptor is expressed in 5 out of 9 ovarian carcinoma cell lines, 15 out of 17 cases of surgical samples and all of normal ovarian surface epithelium, while prolactin transcript is detected only in 1 ovarian carcinoma cell line and in 1 of the surgical samples. For the prolactin receptor-positive ovarian carcinoma cells, exogenous prolactin did not affect the proliferation but markedly inhibited apoptosis. Therefore, actual cell growth was enhanced by prolactin in a dose-dependent manner. The blocking of prolactin receptor by antibody severely impaired the antiapoptotic and growth-promoting effects of prolactin. Interestingly, the cisplatin-induced cell death of the prolactin receptor-positive cells was significantly inhibited by pretreatment with prolactin. These findings indicate a responsiveness of ovarian carcinomas to prolactin and suggest that the prolactin/prolactin receptor system may be a new therapeutic target of ovarian carcinomas.

p53 and mdm2 as prognostic indicators in patients with epithelial ovarian cancer: a multivariate analysis

OBJECTIVE

The aim of the study was to investigate the prognostic significance of p53 and mdm2 protein expressions in epithelial ovarian cancer and their relationship with the clinicopathological variables.

METHODS

Tumor biopsy specimens from 82 patients who were homogenously treated were examined immunohistochemically for expression of p53 and mdm2 proteins. Univariate and multivariate analyses were performed for prognostic factors, and correlations with clinicopathological parameters were examined.

RESULTS

Fifty-four percent and 33% of cases stained positive for p53 and mdm2, respectively. p53 expression was associated with serous type, higher grade, positive cytology, residual tumor and stage of the disease. mdm2 expression predicted of chemosensitivity and it was related with higher grade but not with other clinicopathological variables. Significantly poorer survival was seen for those with p53 (P < 0.05) or mdm2 (P < 0.01) positive tumors than those with negative p53 or mdm2 staining. Coexpression of p53 and mdm2 was also related to poor outcome (P < 0.05). Multivariate analysis revealed that FIGO stage, mdm2 expression, response to chemotherapy and optimal cytoreduction were significant independent prognostic and predictive factors of survival.

CONCLUSION

Although our findings showed that mdm2 may be used as a prognostic indicator in patients with epithelial ovarian cancer, these results should be supported by more and larger studies.

Cyclooxygenase-1 is a potential target for prevention and treatment of ovarian epithelial cancer

The precise genetic and molecular defects underlying epithelial ovarian cancer (EOC) remain largely unknown, and treatment options for patients with advanced disease are limited. Cyclooxygenases (COX-1 and COX-2) catalyze the conversion of arachidonic acid to prostaglandins. Whereas overwhelming evidence suggests a role for COX-2 in a variety of cancers, the contribution of COX-1 remains much less explored. The expression status of COX isoforms in ovarian cancers also remains confusing. We have previously shown that human epithelial ovarian tumors have increased levels of COX-1 but not COX-2. To more carefully examine the role of COXs in ovarian cancer, we used a mouse model of EOC in which genetic and oncogenic modifications were experimentally engineered into ovarian surface epithelial cells (OSE) thought to be the cells of origin for human EOC. These OSE cells produce tumors when allografted into host mice. Using multiple approaches, we observed that OSE cells and the tumors comprised of these cells express high levels of COX-1 but not COX-2. Prostacyclin (PGI(2)) is the major prostaglandin generated downstream of COX-1 in these cells, and SC-560, a COX-1-selective inhibitor, dramatically inhibits PGI(2) production. More importantly, SC-560 reduced the growth of tumors when OSE cells were allografted in nude female mice. In contrast, the COX-2-selective inhibitor celecoxib had little effect on tumor growth. The growth inhibitory effects of SC-560 result from reduced cell proliferation and/or accelerated apoptosis. Our results imply COX-1 as a target for the prevention and/or treatment of EOC.

Expression and mutational analysis of tyrosine kinase receptors c-kit, PDGFRalpha, and PDGFRbeta in ovarian cancers

Most women with epithelial ovarian cancer are diagnosed with advanced disease. Despite surgery and initial tumor reduction by standard chemotherapy, the tumors frequently recur and the patients eventually die of their disease. New drugs that inhibit tyrosine kinase receptors (TKRs) are being investigated for treatment and this study was undertaken to determine the expression and mutational state for 3 TKRs (c-kit, platelet-derived growth factor receptor [PDGFR] alpha, and PDGFR beta) in ovarian cancer. Tissue arrays containing 84 epithelial ovarian tumors were studied by immunohistochemistry with antibodies specific for c-kit, PDGFR alpha, and PDGFR beta. Immunoreactivity was detected in 78% of the tumor to at least one TKR. PDGFR alpha was expressed in the largest percentage of ovarian tumors (58%) whereas 29% expressed PDGFR beta. Two commercial antibodies against c-kit were studied and 33% of the tumors stained with one but only 6% were interpreted as positive with the second antibody. Activation of TKRs may occur through mutations but, by sequence analysis, no mutations were detected in 6 ovarian tumors with elevated immunoreactivity for each of the TKRs (c-kit, PDGFR alpha, and PDGFR beta). Tyrosine kinase receptors could also be activated through autocrine or paracrine stimulation of receptor by its ligand. Of 43 (35%) tumors tested for both c-kit receptor and its ligand (stem cell factor), 15 expressed both proteins indicating the possibility that this autocrine stimulation feedback loop is a factor in the growth of some ovarian cancers. This study demonstrates that PDGFR alpha, PDGFR beta, and c-kit are expressed in a high percentage of epithelial ovarian cancers suggesting that tyrosine kinase inhibitors may be useful in the treatment of these tumors.

Ultrastructure alterations in adriamycin-resistant and cisplatin-resistant human ovarian cancer cell lines exposed to nonlethal ultrasound

Human ovarian cancer cell lines, SKOV3 and its adriamycin-resistant substrain SKOV3/ADR and COC1 and its cisplatin-resistant substrain COC1/DDP, were exposed to nonlethal ultrasound. Ultrastructures in sham-insonated and insonated cells were inspected by transmission electron microscopy, and cytochrome C in cytosol was determined by enzyme-linked immunosorbent assay. Ultrasound exposure led to no significant changes in SKOV3/ADR cells, but tumid mitochondria occurred in SKOV3 cells. Mitochondria changes were also detected in some exposed COC1 and COC1/DDP cells. Apoptotic bodies could be detected in either control or insonated COC1/DDP cells. A few exposed COC1/DDP cells became reticular. Cytochrome C in cytosol in exposed SKOV3/ADR cells was increased but that in exposed COC1/DDP cells was decreased. These findings revealed that the bioeffect of ultrasound on chemosensitive cells was not identical to that of chemoresistant ones, and ultrasound was a potential approach for treatment of drug-resistant ovarian cancers.

In vitro and in vivo characterization of a novel biocompatible polymer–lipid implant system for the sustained delivery of paclitaxel

Recently, a novel chitosan-based implantable formulation (chitosan-ePC) was developed to provide controlled, local release of paclitaxel (PTX) for the treatment of ovarian tumors. Hence, the objective of this study was to evaluate this delivery system in vitro in human ovarian SKOV-3 cells and in vivo in mice with intraperitoneal implants of drug-free or 14C-PTX-chitosan-ePC films. In vitro, 14C-PTX-chitosan-ePC implants (10 mg) provided zero-order constant release of 0.92+/-0.03 pg/day PTX over 5 days. Released PTX retained dose-dependent activity; effectively inhibiting SKOV-3 proliferation with an ED50 of 211 ng/ml of released PTX. Drug-free implants did not affect cell viability or cell morphology of SKOV-3 cells. A sustained, zero-order release of PTX was also seen in vivo over a 2 week period in mice implanted with 14C-PTX-chitosan-ePC films. Correlations between the in vitro and in vivo release of PTX was highly significant (R2 = 0.975). After 2-4 weeks, mice with chitosan-ePC implants did not demonstrate any signs of encapsulation, inflammation or infection. Overall, our in vitro and in vivo results demonstrated zero-order drug release and biocompatibility of the novel chitosan-ePC film. This indicates potential usefulness of chitosan-ePC implants in the sustained and local delivery of anti-neoplastic agents.

CpG-island methylation and epigenetic control of resistance to chemotherapy

Aberrant methylation of CpG islands (CpG-rich regions of DNA associated with the promoters of many genes) is associated with transcriptional inactivation of genes involved in tumour development. Genes involved in key DNA damage response pathways, such as cell-cycle control, apoptosis signalling and DNA repair can frequently become epigenetically silenced and methylated in tumours. This may lead to differences in intrinsic sensitivity of tumours to chemotherapy, depending on the specific function of the gene inactivated. Furthermore, chemotherapy itself may exert a selective pressure on epigenetically silenced drug sensitivity genes present in subpopulations of cells, leading to acquired chemoresistance. Clinical trials of epigenetic therapies are now in progress, and epigenetic profiling using DNA methylation will provide guidance on optimization of the use of these therapies with conventional chemotherapy, as well as helping to identify patient populations who may particularly benefit from such approaches.

Elimination of the differential chemoresistance between the murine B-cell lymphoma LY-ar and LY-as cell lines after arsenic (As2O3) exposure via the overexpression of gsto1 (p28)

PURPOSE

Arsenic, in the form of As(2)O(3), has gained therapeutic importance because it has been shown to be very effective clinically in the treatment of acute promyelocytic leukemia (APL). Via numerous pathways arsenic induces cellular alterations such as induction of apoptosis, inhibition of cellular proliferation, stimulation of differentiation, and inhibition of angiogenesis. Responses vary depending on cell type, dose and the form of arsenic. GSTO1, a member of the glutathione S-transferase superfamily omega, has recently been shown to be identical to the rate-limiting enzyme, monomethyl arsenous (MMA(V)) reductase which catalyzes methylarsonate (MMA(V)) to methylarsenous acid (MMA(III)) during arsenic biotransformation. In this study, we investigated whether arsenic trioxide (As(2)O(3)) induces apoptosis in both chemosensitive and chemoresistant cell lines that varied in their expression of p28 (gsto1), the mouse homolog of GSTO1.

METHODS

The cytotoxicity of arsenic in the gsto1- and bcl-2-expressing chemoresistant and radioresistant LY-ar mouse lymphoma cell line, was compared with that of the LY-ar's parental cell line, LY-as. LY-as cells are radiosensitive, apoptotically permissive, and do not express gsto1 or bcl-2. Cell survival, glutathione (GSH) levels, mitochondrial membrane potential, and stress-activated kinase status after arsenic treatment were examined in these cell lines.

RESULTS

As(2)O(3) induced an equivalent dose- and time-dependent increase in apoptosis in these cell lines. Cellular survival, as measured after a 24-h exposure, was also the same in each cell line. Reduced GSH was modulated in a similar time- and dose-dependent manner. Apoptosis was preceded by loss of mitochondrial membrane potential that triggered caspase-mediated pathways associated with apoptosis. With a prolonged exposure of As(2)O(3), both cell lines showed decreased activation of ERK family members, ERK1, ERK2 and ERK5. As(2)O(3) enhanced the death signals in LY-ar cells through a decrease in GSH, loss of mitochondrial membrane potential, and abatement of survival signals. This effect is similar to that seen when LY-ar cells are treated with thiol-depleting agents or by the removal of methionine and cysteine (GSH precursor) from the growth medium. This response is also completely contrary to that seen for radiation, actinomycin D, VP-16 and other agents, where LY-ar cells do not succumb to apoptosis.

CONCLUSIONS

The overexpression of gsto1 in normally chemoresistant and radioresistant LY-ar cells renders them vulnerable to the cytotoxic effects of As(2)O(3), despite the 30-fold overexpression of the survival factor bcl-2. Gsto1 and its human homolog, GSTO1, may serve as a marker for arsenic sensitivity, particularly in cells that are resistant to other chemotherapeutic agents.

The acquisition of hMLH1 methylation in plasma DNA after chemotherapy predicts poor survival for ovarian cancer patients

Aberrant epigenetic regulation, such as CpG island methylation and associated transcriptional silencing of genes, has been implicated in a variety of human diseases, including cancer. Methylation of genes involved in apoptosis, including the DNA mismatch repair (MMR) gene hMLH1, can occur in tumor models of resistance to chemotherapeutic drugs. However, the relevance for acquired resistance to chemotherapy of patients' tumors remains unsubstantiated. Plasma DNA from cancer patients, including those with ovarian cancer, often contains identical DNA changes as the tumor and provides a means to monitor CpG island methylation changes. We have examined plasma DNA of patients with epithelial ovarian cancer enrolled in the SCOTROC1 Phase III clinical trial for methylation of the hMLH1 CpG island before carboplatin/taxoid chemotherapy and at relapse. Methylation of hMLH1 is increased at relapse, and 25% (34 of 138) of relapse samples have hMLH1 methylation that is not detected in matched prechemotherapy plasma samples. Furthermore, hMLH1 methylation is significantly associated with increased microsatellite instability in plasma DNA at relapse, providing an independent measure of function of the MMR pathway. Acquisition of hMLH1 methylation in plasma DNA at relapse predicts poor overall survival of patients, independent from time to progression and age (hazard ratio, 1.99; 95% confidence interval, 1.20-3.30; P = 0.007). These data support the clinical relevance of acquired hMLH1 methylation and concomitant loss of DNA MMR after chemotherapy of ovarian cancer patients. DNA methylation changes in plasma provide the potential to define patterns of methylation during therapy and identify those patient populations who would be suitable for novel epigenetic therapies.

Use of reverse phase protein microarrays and reference standard development for molecular network analysis of metastatic ovarian carcinoma

Cancer can be defined as a deregulation or hyperactivity in the ongoing network of intracellular and extracellular signaling events. Reverse phase protein microarray technology may offer a new opportunity to measure and profile these signaling pathways, providing data on post-translational phosphorylation events not obtainable by gene microarray analysis. Treatment of ovarian epithelial carcinoma almost always takes place in a metastatic setting since unfortunately the disease is often not detected until later stages. Thus, in addition to elucidation of the molecular network within a tumor specimen, critical questions are to what extent do signaling changes occur upon metastasis and are there common pathway elements that arise in the metastatic microenvironment. For individualized combinatorial therapy, ideal therapeutic selection based on proteomic mapping of phosphorylation end points may require evaluation of the patient's metastatic tissue. Extending these findings to the bedside will require the development of optimized protocols and reference standards. We have developed a reference standard based on a mixture of phosphorylated peptides to begin to address this challenge.

Rankings and symptom assessments of side effects from chemotherapy: insights from experienced patients with ovarian cancer

GOALS OF WORK

Although many patients with ovarian cancer achieve favorable responses to primary chemotherapy, the majority of women will experience recurrence of their cancer. Selection of second- or third-line chemotherapy ultimately depends on patient preferences for different side effects. To better understand this process, we evaluated preferences and symptom distress in patients with ovarian cancer.

PATIENTS AND METHODS

A total of 70 women with ovarian cancer who had previously received at least three cycles of platinum-based chemotherapy and currently undergoing chemotherapy for newly diagnosed or recurrent disease were interviewed in an outpatient chemotherapy clinic. The patients were asked to rank order 27 health states using a modified visual analog scale and to complete the Memorial Symptom Assessment Scale (MSAS).

MAIN RESULTS

Most favorable health states included perfect health, clinical remission and complete control of chemotherapy-induced nausea and vomiting (CINV). Least favorable health states included more severe CINV health states and death. Patients on first-line chemotherapy had less symptom distress, and rated sexual dysfunction, fatigue and memory loss more favorably than patients on second- or third-line chemotherapy (P<0.05). Married patients generally had less symptom distress compared to patients who were not married, but married patients indicated more distress with sexual dysfunction (P=0.04). Married patients rated alopecia less favorably than unmarried patients (P=0.03), but married patients viewed certain CINV health states more favorably (P=0.02-0.04).

CONCLUSIONS

CINV remains one of the most dreaded side effects of chemotherapy. Separate preference profiles exist for patients with newly diagnosed and recurrent disease, as well as for married versus unmarried patients. While MSAS scores and VAS rankings showed consistency across some health states, this was not true for CINV, suggesting that current symptom status may only influence patient preferences for selected side effects.

The epigenetics of ovarian cancer drug resistance and resensitization

Ovarian cancer is the most lethal of all gynecologic neoplasms. Early-stage malignancy is frequently asymptomatic and difficult to detect and thus, by the time of diagnosis, most women have advanced disease. Most of these patients, although initially responsive, eventually develop and succumb to drug-resistant metastases. The success of typical postsurgical regimens, usually a platinum/taxane combination, is limited by primary tumors being intrinsically refractory to treatment and initially responsive tumors becoming refractory to treatment, due to the emergence of drug-resistant tumor cells. This review highlights a prominent role for epigenetics, particularly aberrant DNA methylation and histone acetylation, in both intrinsic and acquired drug-resistance genetic pathways in ovarian cancer. Administration of therapies that reverse epigenetic "silencing" of tumor suppressors and other genes involved in drug response cascades could prove useful in the management of drug-resistant ovarian cancer patients. In this review, we summarize recent advances in the use of methyltransferase and histone deacetylase inhibitors and possible synergistic combinations of these to achieve maximal tumor suppressor gene re-expression. Moreover, when used in combination with conventional chemotherapeutic agents, epigenetic-based therapies may provide a means to resensitize ovarian tumors to the proven cytotoxic activities of conventional chemotherapeutics.

Prediction of chemotherapeutic response in ovarian cancer with DNA microarray expression profiling

Ovarian carcinoma is a leading cause of gynecologic cancer death in women. Despite treatment, a large number of women with ovarian cancer eventually relapse and die of the disease. Hence, recurrent ovarian cancer continues to be a therapeutic dilemma, possibly a result of the emergence of drug resistance during relapse. Recent advances in expression genomics enable global transcript analysis that leads to molecular classification of cancers and prediction of outcome and treatment response. We did a cDNA microarray examination of the expression profiles of eight primary ovarian cancers stratified into two groups based on their chemotherapeutic response. We applied a voice-speech-pattern recognition algorithm for microarray data analysis and were able to model and predict the response of these patients to chemotherapy from their expression profiles. Hence, gene expression profiling by means of DNA microarray may be applied diagnostically for predicting treatment response in ovarian cancer.

Using microarrays to predict resistance to chemotherapy in cancer patients

Chemotherapy resistance remains a major obstacle to successful treatment and better outcome in cancer patients. The advent of whole genome experimental strategies, such as DNA microarrays, has transformed the way researchers approach cancer research. There is considerable hope that microarray technology will lead to the identification of new targets for therapeutic intervention, a better understanding of the disease process, and, ultimately, to higher survival rates and more personalized medicine. The question at hand is what is the best approach to apply these new technologies to the study of anticancer drug resistance, and how can the results obtained in the laboratory be quickly moved to a clinical setting? This review offers an overview of the microarray technology, including its recently associated strategies, such as array comparative genomic hybridization and promoter arrays. It also highlights some recent examples of microarray studies, which represent a first step toward a better understanding of drug resistance in cancer and, ultimately, personalized medicine.

Hepatocyte growth factor sensitizes human ovarian carcinoma cell lines to paclitaxel and cisplatin

The hepatocyte growth factor (HGF) receptor, encoded by the MET oncogene, is expressed in approximately 70% of human ovarian carcinomas and overexpressed in 30% of cases. Because HGF is known to protect cells from apoptosis, we investigated whether receptor expression modifies ovarian cancer cell response to chemotherapy. The apoptotic effect of the front-line chemotherapeutic drugs paclitaxel and cisplatin on cells treated with HGF was studied. In ovarian cancer cell lines, pretreatment with HGF surprisingly enhances the apoptotic response to low doses of paclitaxel and cisplatin. HGF empowers specifically the intrinsic apoptotic pathway, whereas it protects cells from extrinsic Fas-induced apoptosis. Chemotherapy sensitization is specific for HGF because another growth factor (e.g., epidermal growth factor) increases ovarian cancer cell survival. In nonovarian cancer cell models, as expected, HGF provides protection from drug-induced apoptosis. These data show that HGF sensitizes ovarian carcinoma cells to low-dose chemotherapeutic agents. This suggests that HGF may be used to improve response to chemotherapy in a set of human ovarian carcinomas molecularly classified based on the MET oncogene expression.

Targeted therapy for epithelial ovarian cancer: Current status and future prospects

Despite advances in surgery and chemotherapy, less than 20% of patients with stage III or IV ovarian cancer survive long-term. In the past, cytotoxic regimens have been developed empirically, combining active agents at maximally tolerated doses, often without a clear rationale for their interaction. Advances in understanding the biology of ovarian cancer have identified multiple molecular targets that differ in normal and malignant cells. Targets include cell cycle regulators, growth factor receptors, signal transduction pathways, molecules that confer drug resistance, and angiogenic mechanisms. A number of targeted agents have entered clinical trials. Small molecular weight inhibitors, monoclonal antibodies, and antisense and gene therapy are all being evaluated alone and in combination with cytotoxic drugs. In contrast to earlier studies, the impact of each agent on the designated target can be assessed and agents can be matched to the genotype and phenotype of malignant and normal cells. In the long run, this should facilitate individualization of more effective, less toxic therapy for women with ovarian cancer.