P53 and Bcl-2 as prognostic predictors in epithelial ovarian cancer

Bax, Bcl-2, and Bax/Bcl-2 as prognostic markers in acute myeloid leukemia: are we ready for Bcl-2-directed therapy?

Purpose

Many anticancer drugs induce apoptosis in malignant cells, and resistance to apoptosis could lead to suboptimal or no therapeutic benefit. Two cytoplasmic proteins, B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax) and Bcl-2, act as a promoter and an inhibitor of apoptosis, respectively. Both Bax and Bcl-2 as well as their ratio have been regarded as prognostic markers in various cancers. However, conflicting results have been reported. A clear understanding of apoptosis has also become crucial due to reports about anti-Bcl-2 chemotherapy. We explored the relationship of Bax and Bcl-2 gene expression and their ratio with the therapeutic response in acute myeloid leukemia (AML) patients.

Patients and methods

Bone marrow and/or blood samples from 90 AML patients treated with cytarabine and daunorubicin were included. Expression of Bax and Bcl-2 was determined through real-time polymerase chain reaction by using ΔΔCt method of relative expression.

Results

Bax and Bcl-2 expression among marrow and blood samples correlated with each other (r_s=0.5, p<0.01). Although bone marrow expression of Bax and Bcl-2 tended to remain higher among responders (median 1.01 and 0.29, respectively) as compared to non-responders (median 0.66 and 0.24, respectively), the difference failed to reach statistical significance (U=784.5 and 733; p=0.68 and 0.28, respectively). Conversely, Bax/Bcl-2 ratio was higher among poor responders (median 3.07 vs 1.78), though again failed to reach statistical significance (U=698.5, p=0.07).

Conclusion

Expression of Bax and Bcl-2 does not differ significantly among AML patients treated with cytarabine and daunorubicin in terms of remission, relapse, resistance, overall survival, and disease-free survival, thus questioning the utility of emerging anti-Bcl-2 therapy.

Wilms' tumor gene 1 immunotherapy in pelvic gynecological malignancies

Pelvic gynecological malignancies account for 6% of all cancers. In the relapsed state, classical treatments are limited. There is an urgent need for new and personalized treatment. Wilms' tumor gene 1 (WT1) is the most important tumor-associated antigen. Although highly present in gynecological tumors, active immunotherapy against it is still underexplored. This review gives an insight into the importance of WT1 in pelvic gynecological malignancies and the first taken steps into the world of WT1 immunotherapy.

Tissue biomarkers in prognostication of serous ovarian cancer following neoadjuvant chemotherapy

Serous ovarian cancer (SOC) is a significant cause of morbidity and mortality in females with poor prognosis because of advanced stage at presentation. Recently, neoadjuvant chemotherapy (NACT) is being used for management of advanced SOC, but role of tissue biomarkers in prognostication following NACT is not well established. The study was conducted on advanced stage SOC patients (n = 100) that were treated either conventionally (n = 50) or with NACT (n = 50), followed by surgery. In order to evaluate the expression of tissue biomarkers (p53, MIB1, estrogen and progesterone receptors, Her-2/neu, E-cadherin, and Bcl2), immunohistochemistry and semiquantitative scoring were done following morphological examination. Following NACT, significant differences in tumor histomorphology were observed as compared to the native neoplasms. MIB 1 was significantly lower in cases treated with NACT and survival outcome was significantly better in cases with low MIB 1. ER expression was associated with poor overall survival. No other marker displayed any significant difference in expression or correlation with survival between the two groups. Immunophenotype of SOC does not differ significantly in samples from cases treated with NACT, compared to upfront surgically treated cases. The proliferating capacity of the residual tumor cells is less, depicted by low mean MIB1 LI. MIB 1 and ER inversely correlate with survival.

Pathway modulations and epigenetic alterations in ovarian tumorbiogenesis

Cellular pathways are numerous and are highly integrated in function in the control of cellular systems. They collectively regulate cell division, proliferation, survival and apoptosis of cells and mutagenesis of key genes that control these pathways can initiate neoplastic transformations. Understanding these pathways is crucial to future therapeutic and preventive strategies of the disease. Ovarian cancers are of three major types; epithelial, germ-cell, and stromal. However, ovarian cancers of epithelial origin, arising from the mesothelium, are the predominant form. Of the subtypes of ovarian cancer, the high-grade serous tumors are fatal, with low survival rate due to late detection and poor response to treatments. Close examination of preserved ovarian tissues and in vitro studies have provided insights into the mechanistic changes occurring in cells mediated by a few key genes. This review will focus on pathways and key genes of the pathways that are mutated or have aberrant functions in the pathology of ovarian cancer. Non-genetic mechanisms that are gaining prominence in the pathology of ovarian cancer, miRNAs and epigenetics, will also be discussed in the review.

The consequence of oncomorphic TP53 mutations in ovarian cancer

Ovarian cancer is the most lethal gynecological malignancy, with an alarmingly poor prognosis attributed to late detection and chemoresistance. Initially, most tumors respond to chemotherapy but eventually relapse due to the development of drug resistance. Currently, there are no biological markers that can be used to predict patient response to chemotherapy. However, it is clear that mutations in the tumor suppressor gene TP53, which occur in 96% of serous ovarian tumors, alter the core molecular pathways involved in drug response. One subtype of TP53 mutations, widely termed gain-of-function (GOF) mutations, surprisingly converts this protein from a tumor suppressor to an oncogene. We term the resulting change an oncomorphism. In this review, we discuss particular TP53 mutations, including known oncomorphic properties of the resulting mutant p53 proteins. For example, several different oncomorphic mutations have been reported, but each mutation acts in a distinct manner and has a different effect on tumor progression and chemoresistance. An understanding of the pathological pathways altered by each mutation is necessary in order to design appropriate drug interventions for patients suffering from this deadly disease.

Immunohistochemistry with apoptotic-antiapoptotic proteins (p53, p21, bax, bcl-2), c-kit, telomerase, and metallothionein as a diagnostic aid in benign, borderline, and malignant serous and mucinous ovarian tumors

Background

In many tumors including ovarian cancer, cell proliferation and apoptosis are important in pathogenesis and there are many alterations in most of the genes related to the cell cycle. This study was designed to evaluate immunohistochemistry with apoptotic-antiapoptotic proteins (p53, p21, bax, and bcl-2), c-kit, telomerase, and metallothionein as a diagnostic aid in typing of benign, borderline, and malignant serous and mucinous ovarian tumors.

Methods

Total of 68 ovarian tumors, 25 benign [13 (19.1%) serous and12 (17.6%) mucinous], 16 borderline [9 (13.2%) serous and 7(10.3%) mucinous], and 27 malignant ovarian tumors [24 (35.3%) serous and 3 (4.4%) mucinous tumors] were included in the study. Immunohistochemical expression of p53, p21, bax, bcl–2, telomerase, c-kit, and metallothionein were evaluated.

Results

When all 68 cases were evaluated as benign, borderline, and malignant ovarian tumors without considering histopathological subtypes, the p53, p21, bax and metallothionein showed significantly higher staining scores in the borderline and malignant ones (p < 0.05). After evaluation of all 68 cases, the serous tumors showed significantly higher staining scores of p53, p21, c-kit, and metallothionein compared to the mucinous ones (p < 0.05). For differentiation of benign and borderline and malignant tumors combined, p53 was not used because all benign tumors has no staining, and p21, bax, and metallothionein was determined the significant predictors for borderline and malignant tumors combined (p < 0.05). For differentiation of borderline and malignant tumors, only p53 was determined the significant predictor for malignant tumors (p < 0.05).

Conclusions

In conclusion, p53, p21, bax, c-kit, and metallothionein may be helpful for the typing of ovarian tumors as benign, borderline and malignant or serous and mucinous. p53, p21, bax, c-kit, and metallothionein may have different roles in the pathogenesis of ovarian tumor types. p53 and metallothionein may be helpful in the typing of borderline and malignant ovarian tumors. The immunohistochemical staining with bcl-2 and telomerase may not provide meaningful contribution for the typing of ovarian tumors.

Virtual slide

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2013030833768498

Pilot study of CD147 protein expression in epithelial ovarian cancer using monoclonal antibody 12C3

AIM

CD147 is a membrane glycoprotein that is expressed in various cancer cells and is involved in tumor invasion and metastasis by inducing stromal fibroblastic cells to produce matrix metalloproteinases. This study was carried out to evaluate the correlation between CD147 expression and various clinicopathologic parameters, including histological grade and prognosis in a small sample set of human ovarian cancer patients.

MATERIAL AND METHODS

Paraffin-embedded surgical tissue samples from 25 patients with ovarian serous and endometrioid adenocarcinoma were stained with anti-CD147 antibody (monoclonal antibody 12C3: MoAb 12C3) for immunohistochemical analysis.

RESULTS

CD147 protein was expressed in 84.0% (21 of 25 cases) of cancerous lesions, but not in normal lesions. CD147 expression by ovarian cancer cells was inversely correlated with overall survival. There was no correlation between CD147 expression and histological grade.

CONCLUSIONS

These results suggest that measurement of CD147 expression may enhance the understanding of the pathophysiology of epithelial ovarian cancer.

Predictive and prognostic protein biomarkers in epithelial ovarian cancer: recommendation for future studies

Epithelial ovarian cancer is the most lethal gynecological malignancy. Due to its lack of symptoms, this disease is diagnosed at an advanced stage when the cancer has already spread to secondary sites. While initial rates of response to first treatment is >80%, the overall survival rate of patients is extremely low, mainly due to development of drug resistance. To date, there are no reliable clinical factors that can properly stratify patients for suitable chemotherapy strategies. Clinical parameters such as disease stage, tumor grade and residual disease, although helpful in the management of patients after their initial surgery to establish the first line of treatment, are not efficient enough. Accordingly, reliable markers that are independent and complementary to clinical parameters are needed for a better management of these patients. For several years, efforts to identify prognostic factors have focused on molecular markers, with a large number having been investigated. This review aims to present a summary of the recent advances in the identification of molecular biomarkers in ovarian cancer patient tissues, as well as an overview of the need and importance of molecular markers for personalized medicine in ovarian cancer.

Correlation Between Immunohistochemical Biomarkers Expression and Prognosis of Ovarian Carcinomas in Tunisian Patients

Background

Ovarian cancer is the leading cause of death from gynaecological malignancies. Newer biological prognostic factors and predictors of response to therapy are needed. Our study was designed to evaluate the expression of p53, Bcl-2, Estrogen receptor (ER) and Progesterone receptor (PR) in ovarian carcinoma and to compare it with other prognostic parameters such as age, FIGO stage, size of residual tumor, histological type and grade.

Methods

This is a retrospective study conducted in the department of pathology at Sfax University Hospital. Confirmed 57 cases of ovarian carcinoma were reviewed in the period between January 1995 and December 2006. We used immunohistochemistry to evaluate the expression of p53, Bcl-2, ER and PR receptors and Chi-Square and Student test to correlate immunohistochemical findings with some prognostic parameters of ovarian carcinoma.

Results

The percentage of expression of p53, Bcl-2, ER and PR was 73,7; 47,4; 35,1 and 33,3 % respectively. p53 overexpression correlated with an advanced FIGO stage (p = 0,026) and presence of ascitis (p < 10^-4). The expression of PR was associated with an early stage (FIGO I and II), a non serous histologic type and a low tumour grade (p = 0,045; 0,010 and 0,036 respectively). No correlation was found between Bcl-2 and ER and prognostic parameters. Survival analysis revealed that Bcl-2 status, FIGO stage, presence of ascites, peritoneal cytology, and residual disease were significant predictive factors of survival.

Conclusion

p53 expression correlates with a worse prognosis in epithelial ovarian cancer, whereas Bcl-2 expression is related to a better outcome. For hormonal status, expression of PR is found to be an independent indicator of favourable prognosis. These results should be supported by more and larger studies.

Modest effect of p53, EGFR and HER-2/neu on prognosis in epithelial ovarian cancer: a meta-analysis

BACKGROUND

P53, EGFR and HER-2/neu are the most frequently studied molecular biological parameters in epithelial ovarian cancer, but their prognostic impact is still unequivocal. We performed a meta-analysis to more precisely estimate their prognostic significance.

METHODS

Published studies that investigated the association between p53, EGFR and HER-2/neu status and survival were identified. Meta-analysis was performed using a DerSimonian-Laird model. Publication bias was investigated using funnel plots and sources of heterogeneity were identified using meta-regression analysis.

RESULTS

A total of 62 studies were included for p53, 15 for EGFR and 20 for HER-2/neu. P53, EGFR and HER-2/neu status had a modest effect on overall survival (pooled HR 1.47, 95% CI 1.33-1.61 for p53; HR 1.65, 95% CI 1.25-2.19 for EGFR and HR 1.67, 95% CI 1.34-2.08 for HER-2/neu). Meta-regression analysis for p53 showed that FIGO stage distribution influenced study outcome. For EGFR and HER-2/neu, considerable publication bias was present.

CONCLUSIONS

Although p53, EGFR and HER-2/neu status modestly influences survival, these markers are, by themselves, unlikely to be useful as prognostic markers in clinical practice. Our study highlights the need for well-defined, prospective clinical trials and more complete reporting of results of prognostic factor studies.

Urinary levels of Bcl-2 are elevated in ovarian cancer patients

OBJECTIVE(S)

The poor prognosis associated with ovarian cancer is due to the lack of overt early symptoms and the absence of reliable diagnostic screening methods. Since many tumors overexpress anti-apoptotic proteins, the purpose of this study was to determine whether elevated levels of the anti-apoptotic protein Bcl-2 were present in urine from patients with ovarian cancer.

METHODS

Bcl-2 was assayed by ELISA in urine samples from two cohorts consisting of a total of 77 healthy women, 161 women with benign gynecologic disease and 150 women with ovarian cancer, 13 with early and 137 with late stage disease, respectively. Wherever possible, parallel serum samples were measured for CA125 levels by ELISA.

RESULTS

Urinary levels of Bcl-2 from healthy individuals or women with benign disease averaged 0.59 ng/ml+/-0.61 and 1.12 ng/ml+/-0.79, respectively. In contrast, urinary levels of Bcl-2 averaged 2.60 ng/ml+/-2.23 and 3.58 ng/ml+/-1.55 from women with early (N=13) and late (N=137) stage ovarian cancer. Further, urinary levels of Bcl-2 were elevated in ovarian cancer patients regardless of tumor grade, stage, size, histologic subtype, creatinine levels or patient age, but appeared to complement CA125 measurements.

CONCLUSION(S)

Levels of Bcl-2 are elevated in the urine of patients with ovarian cancer and may be of diagnostic and/or prognostic clinical importance. Further studies of urinary Bcl-2 as a biomarker for ovarian cancer alone or in combination with other markers are warranted.

P53 and bcl-2 assessment in serous ovarian carcinoma

The study objective was to determine the prognostic value of assessment of staining of p53 and bcl-2 in a well-selected group of serous ovarian carcinomas. Immunohistochemical detection was used to identify both p53 and bcl-2 positive tumors. One hundred thirty-two tumors were analyzed for positivity of staining, grade of staining intensity, and for p53 alone, percent expression rates. These were analyzed alongside traditional clinicopathologic parameters for their ability to predict overall survival (OS), disease-free survival (DFS), and response to chemotherapy (CR). Univariate COX analysis revealed percent p53 expression (P = 0.012) and p53 grade (P = 0.01) to be significant predictors of DFS. Neither the p53 nor bcl-2 measurement parameters were found significant for OS or prediction of CR. On multivariate analysis, incorporating clinicopathologic parameters, p53 parameters did not retain independent significance for any outcome measure. As in primary reported studies, bcl-2 was not found to be of clear independent prognostic value in this group of ovarian tumors. If mutation of p53 and its consequent overexpression is an early event in ovarian tumorigenesis, then p53 assessment may prove useful prognostically in the assessment of either low-grade ovarian carcinomas, as a possible indicator for progression, or in early-stage ovarian tumors, as a marker of tumor aggression or likelihood of recurrence. p53 analysis of a larger group of stage I ovarian tumors would be desirable to further explain the potential association with DFS.

Clinicopathological significance of WT1 expression in ovarian cancer: a possible accelerator of tumor progression in serous adenocarcinoma

Recently, oncogenic potential of the WT1 gene has been proposed in some human solid tumors and leukemias. Although previous studies have shown the frequent expression of the WT1 protein in ovarian serous adenocarcinomas (OSAs), its clinicopathologic significance is still unclear. We immunohistochemically examined the expression status of WT1 in 119 OSAs and analyzed the correlation of the intensity of WT1 immunoreactivity with the level of WT1 mRNA expression by quantitative real-time polymerase chain reaction, clinicopathologic variables, expression of p53, Bcl-2, and Ki-67 labeling index (LI). Of 119 OSAs, nuclear WT1 immunoreactivity was positive in 99 (83%), of which 44 (44%) and 55 (56%) exhibited high and low WT1 immunoreactivities, respectively. The quantitative WT1 mRNA levels were significantly correlated with the intensity of WT1 immunoreactivity (P < 0.05). In comparison with WT1-negative OSAs, the WT1-positive OSAs showed a higher grade (P = 0.007), advanced stage (P = 0.018), and higher Ki-67 LI (P < 0.001). Additionally, high WT1 immunoreactivity was correlated with a higher grade (P = 0.003), Ki-67 LI (P = 0.012), Bcl-2 expression (P = 0.003), and poorer patient outcome (5-year survival, 36.5 vs 63.8%, P = 0.008 by log-rank test). The WT1 protein may be an accelerator of the progression of OSA.

The impact of c-kit and ki-67 expression on patients prognosis in advanced ovarian serous carcinoma

The transmembrane-tyrosine-kinase receptor, c-kit, is involved in cell differentiation and has been found to be expressed in normal human cell types and solid tumors. This study was designed to investigate the effects of c-kit expression on: 1) tumor proliferation and apoptosis, and 2) survival in patients with high-grade advanced stage ovarian serous carcinoma (OSC). We identified 118 patients with high-grade advanced stage OSC from our files. Clinical data, including demographics and overall survival, were collected. Immunohistochemical panel consisting of c-kit, ki-67, p53, and bcl-2 was performed. C-kit was categorized as positive if any cytoplasmic or membranous staining pattern was identified. Correlation between c-kit expression and the other markers was performed. Survival analysis was performed using COX proportional hazards regression and Kaplan-Meier test. Of 118 cases, 25 (21.2%) expressed c-kit. Of 93 c-kit-negative tumors, 87.1% had a high proliferation index. High p53 and bcl-2 expression was identified in 96 (81.4%) and 59 (50%) cases respectively. No significant statistical correlation was identified between c-kit and apoptosis markers. Tumors lacking c-kit expression showed a trend toward having high proliferation index, but this did not achieve statistical significance (p = 0.07). Of the seven variables included in the multivariate survival analysis, only c-kit (odds ratio, 2.12; 95% confidence interval, 08-4.17; p = 0.02) and ki-67 (odds ratio, 1.9; 95% confidence interval, 1.1-3.1; p = 0.03) showed an independent statistically significant impact on survival. High-grade advanced stage OSC lacking c-kit expression correlates with poor outcome. Interestingly, cases lacking c-kit expression also showed a trend to have high proliferation index.

Role of estrogen and progesterone in the survival of ovarian tumors--a study of the human ovarian adenocarcinoma cell line OC-117-VGH

BACKGROUND

The role of estrogen and progesterone in ovarian carcinogenesis and the growth and survival of ovarian cancer cells is controversial. In this study, we tested the effects of various concentrations of estrogen and progesterone on the survival of an ovarian cancer cell line.

METHODS

The ovarian adenocarcinoma cell line, OC-117-VGH, is deficient in the following receptors: estrogen receptor (ER)alpha, ERbeta, and progesterone receptor (PR). Serial concentrations of estrogen and progesterone were used to evaluate the effects of estrogen and progesterone on the survival of ovarian cancer cells. The apoptosis-related genes Bcl-2 and Bax were used to check the possible mechanism of an estrogen or progesterone effect on survival of the cancer cell line.

RESULTS

Estrogen 0.01-1.0 microM and progesterone 0.1-10.0 microM affected cell survival. As predicted, progesterone successfully downregulated anti-apoptotic Bcl-2 expression, and dose-dependently suppressed Bcl-2 expression in tumor cells. Paradoxically, estrogen showed the same effects. In addition, both hormones downregulated proapoptotic Bax expression. The net effect confirmed the role of downregulated Bcl-2 in reducing the survival of ovarian cancer cells.

CONCLUSION

Based on the findings of decreased survival and/or growth in OC-117-VGH ovarian adenocarcinoma cells treated with either estrogen or progesterone, we suspect that both hormones act effectively against ER-negative and PR-negative ovarian cancer cells. These findings should lead to a reassessment of hormone therapy for ovarian cancers.

Prognostic significance of p53, Her-2, and EGFR overexpression in borderline and epithelial ovarian cancer

The objective of the study was to evaluate the prognostic effect of p53, Her-2, and EGFR in borderline and epithelial ovarian cancer. Tumor tissue from 85 patients with borderline and 783 patients with epithelial ovarian cancer stage I-IV were analyzed immunohistochemically for p53 positivity and over-expression of Her-2 and EGFR. In the ovarian cancer (OC) group 415 patients (53%) had p53-positive tumors, 272 (35%) had tumors with Her-2 over-expression, and 483 (62%) had over-expression of EGFR. In the OC group the classical prognostic factors (older age, higher FIGO stage, and poorer differentiated stage) had significant prognostic value in both uni- and multivariate analyses. Multivariate analyses in the OC group proved p53 positivity to increase mortality significantly depending on the grade of the tumor. Her-2 likewise increased the risk of mortality significantly in this group depending on the grade of the tumor. EGFR on the other hand did not have any additional prognostic effect in the OC group after adjustment for the classical prognostic and molecular factors was made. In the borderline group Her-2 and EGFR over-expression in combination, adjusted for age and p53, significantly improved the prognosis.

Cyclin D1, p53, and p21Waf1/Cip1 expression is predictive of poor clinical outcome in serous epithelial ovarian cancer

PURPOSE

Dysregulation of cell cycle control, in particular G(1)-S-phase transition, is implicated in the pathogenesis of most human cancers, including epithelial ovarian cancer (EOC). However, the prognostic significance of aberrant cell cycle gene expression in EOC remains unclear.

EXPERIMENTAL DESIGN

The expression of selected genes from the pRb pathway that regulates G(1)-S-phase progression, including cyclin D1, p16(Ink4a), cyclin E, p27(Kip1), p21(Waf1/Cip1), and p53, was examined in a consecutive series of 134 serous EOC using immunohistochemistry and the results correlated to disease outcome.

RESULTS

Molecular markers predictive of reduced overall survival in univariate analysis were overexpression of cyclin D1 (P = 0.03) and p53 (P = 0.03) and reduced expression of p27(Kip1) (P = 0.05) and p21(Waf1/Cip1) (P = 0.02), with the latter three also being prognostic for a shorter progression-free interval. In addition, patients displaying overexpression of p53 with concurrent loss of p21(Waf1/Cip1) had a significantly shorter overall (P = 0.0008) and progression-free survival (P = 0.0001). On multivariate analysis, overexpression of cyclin D1 and combined loss of p21(Waf1/Cip1) in the presence of p53 overexpression were independent predictors of overall survival. Similarly, the combination of p21(Waf1/Cip1) loss and p53 overexpression was independently predictive of a shorter progression-free interval. Overexpression of p53 and cyclin E and reduced expression of p27(Kip1) and p21(Waf1/Cip1) were significantly associated with increasing tumor grade.

CONCLUSIONS

This study confirms that dysregulation of cell cycle genes is common in EOC, and that aberrant expression of critical cell cycle regulatory proteins can predict patient outcome in serous EOC.

Expression of Bcl-xL in ovarian carcinoma is associated with chemoresistance and recurrent disease

OBJECTIVE

The long-term survival of patients with epithelial ovarian cancer is limited by the emergence of tumor cells that are resistant to chemotherapy. We hypothesized that expression of Bcl-x(L), a homologue of Bcl-2 that confers protection from chemotherapy-induced apoptosis, may be predictive of patients' clinical response to treatment, and that treatment with chemotherapy may result in the selection of tumor cells that overexpress this protein.

METHODS

We determined the expression of Bcl-x(L) in epithelial ovarian cancers from 28 patients at the time of initial staging laparotomy and in recurrent tumors in the same patients following treatment with platinum-based chemotherapy. The data were analyzed to determine whether Bcl-x(L) expression was predictive of clinical outcome. A2780 ovarian cancer cells were stably transfected with Bcl-x(L) or control plasmid. Chemotherapy-induced apoptosis in these cell lines was determined in vitro and in a xenograft model.

RESULTS

Bcl-x(L) expression in primary tumors was associated with a significantly shorter disease-free interval as compared to patients whose tumors did not express Bcl-x(L) (1.6 months as compared to 7.7 months). We found that Bcl-x(L) expression conferred resistance to chemotherapy-induced apoptosis resulting from treatment with cisplatin, paclitaxel, topotecan, and gemcitabine in vitro. In a xenograft model, Bcl-x(L) expressing tumors continued to grow following treatment with cisplatin, paclitaxel, topotecan, and gemcitabine, in contrast to control tumors, which disappeared.

CONCLUSION

These results portray an important role for Bcl-x(L) as a key factor associated with chemotherapy failure in the treatment of ovarian cancer.