Independence of the prognostic value of tumor suppressor protein expression in ovarian adenocarcinomas: A multivariate analysis of expression of p53, retinoblastoma, and related proteins

Development of a novel immunoassay to detect interactions with the transactivation domain of p53: application to screening of new drugs

Tumor protein p53 acts as a trans-activator that negatively regulates cell division by controlling a set of genes required for cell cycle regulation, making it a tumor suppressor in different types of tumors. Because the transcriptional activity of p53 plays an important role in the occurrence and development of tumors, reactivation of p53 transcriptional activity has been sought as a novel cancer therapeutic strategy. There is great interest in developing high-throughput assays to identify inhibitors of molecules that bind the transcription-activation domain of p53, especially for wt p53-containing tumors. In the present study, taking MDM2 as an example, a novel amplified luminescent proximity homogeneous assay (AlphaLISA) was modified from a binding competition assay to detect the interactions between the transcription-activation domain of p53 and its ligands. This assay can be adapted as a high-throughput assay for screening new inhibitors. A panel of well-known p53-MDM2 binding inhibitors was used to validate this method, and demonstrated its utility, sensitivity and robustness. In summary, we have developed a novel protein-protein interaction detection immunoassay that can be used in a high-throughput format to screen new drug candidates for reactivation of p53. This assay has been successfully validated through a series of p53-MDM2 binding inhibitors.

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.

Serum and tissue biomarkers as predictive and prognostic variables in epithelial ovarian cancer

Tumour stage, residual disease after initial surgery, histological type and tumour grade are the most important clinical-pathological factors related to the clinical outcome of patients with epithelial ovarian cancer. In the last years, several investigations have assessed different biological variables in sera and in tissue samples from patients with this malignancy in order to detect biomarkers able to reflect either the response to chemotherapy or survival. The present paper reviewed the literature data about the predictive or prognostic relevance of serum CA 125, soluble cytokeratin fragments, serum human kallikreins, serum cytokines, serum vascular endothelial growth factor and plasma d-dimer as well as of tissue expression of cell cycle- and apoptosis-regulatory proteins, human telomerase reverse transcriptase, membrane tyrosine kinase receptors and matrix metalloproteinases. A next future microarray technology will hopefully offer interesting perspectives of translational research for the identification of novel predictive and prognostic biomarkers for epithelial ovarian cancer.

Human papilloma virus (HPV) status, p16INK4a, and p53 overexpression in epithelial malignant and borderline ovarian neoplasms

This investigation is the first to evaluate simultaneously human papilloma virus (HPV) status, p16(INK4a), and p53 immunoreactivity in epithelial ovarian neoplasms. The results were analyzed and correlated with histological type, histological grade, and survival of patients. Subtypes considered are papillary serous and mucinous. Polymerase chain reaction (PCR) analysis, performed in our previous study, had already demonstrated a small number of HPV-positive epithelial ovarian neoplasms. No significant correlation was found between the presence of HPV DNA and subtypes of ovarian neoplasms; thus, HPV cannot be considered responsible for epithelial ovarian neoplasm. Since p16 immunoreactivity was present in many other HPV-negative cases of epithelial ovarian neoplasms, this study suggests that p16 overexpression in some neoplasms of the female genital tract is not related to HPV carcinogenesis. A higher p53 expression rate observed between borderline and malignant serous tumors and between serous and mucinous neoplasms can confirm a recent dualistic model of ovarian carcinogenesis. According to this theory, low-grade serous carcinomas (serous intraepithelial carcinomas, serous borderline neoplasm, and ovarian mucinous neoplasms) (type I tumors) develop from mutations of KAS and BRAF, while high-grade serous carcinomas (type II tumors) develop from mutation of p53. In malignant neoplasms, for univariate analysis, patient survival seems to be related to p53, strong and diffuse p16 overexpression, and the stage of development of neoplasms at the diagnosis. In multinomial logistic regression, used to evaluate the role of staging, grading, p16 and p53 immunopositivity as predictor variables of unfavorable outcome of the disease, only p16 positivity was significantly related to the poor prognosis of the cancer.

Significance of E2F-1 overexpression in epithelial ovarian cancer

E2F-1 is a downstream regulator of the Rb pathway and is a transcription factor that plays a key role in the control of cell cycle progression. Deregulation of E2F-1 expression and Rb pathway is involved in carcinogenesis. The aim of this study was to evaluate E2F-1 expression and Rb pathway alteration and to elucidate their correlation with clinical and pathologic parameters in epithelial ovarian cancer (EOC). We investigated overexpression of E2F-1 and alterations of p16(INK4a), cyclin D1, CDK4, and pRb using immunohistochemistry and tissue microarray methods in 72 EOC patients. Overexpression of E2F-1 was detected in 45.8% of samples. The overall abnormal expression frequencies of p16(INK4a), cyclin D1, CDK4, and pRb were 33.3%, 11.1%, 12.5%, and 38.9%, respectively. E2F-1 overexpression was not associated with alteration of the Rb pathway. E2F-1 overexpression was correlated with FIGO stage, histologic grade, and mitotic index; it was a valuable prognostic variable along with FIGO stage in the multivariated analysis. The results suggest that E2F-1 has a growth-promoting effect in EOC and that E2F-1 overexpression may provide a useful prognostic indicator for EOC.

[Overexpression and prognostic value of p53 and HER2/neu proteins in benign ovarian tissue and in ovarian cancer]

BACKGROUND AND OBJECTIVE

To investigate the prognostic value of p53 and HER2/neu overexpression in epithelial ovarian cancer (EOC).

PATIENTS AND METHOD

p53 and HER2/neu immunostaining were performed in 198 tissue samples, 124 EOC, 44 benign ovarian tumors and 30 normal ovaries. Nuclear p53 and membranous HER2/neu immunostaining were evaluated.

RESULTS

Neither p53 nor HER2/neu overexpression was seen in the benign ovarian tumors. HER2/neu immunostaining was observed in one normal ovary. P53 overexpression was found in 25% EOC and was related with advanced stage, endometrioid, clear cell and undifferentiated types, grade G3, and sub-optimal surgery. HER2/neu immunostaining was observed in 24.2% and it was associated with advanced stage, clear cell and undifferentiated types, and suboptimal surgery. Both, p53 and HER2/neu overexpression decreased overall and progression-free survival, but in the multivariant analysis, only HER2/neu overexpression was an independent prognostic factor of overall survival (RR = 2.8; 95% confidence interval [CI], 1.2-5.6) and recurrence (RR = 2.8; 95% CI, 1.1-7.1). Simultaneous p53 and HER2/neu overexpression made the prognosis worse (p < 0.01).

CONCLUSIONS

HER2/neu overexpression (but not p53 overexpression) is a major prognostic factor in EOC.

Relationship between p53-associated proteins and estrogen receptor status in ovarian serous neoplasms

We studied the immunoexpression of p14ARF, MDM2, and p53, in addition to relationships between those protein expressions and estrogen receptor (ER)alpha in ovarian serous tumors including benign (n= 23), borderline (n= 41), and malignant (n= 94). The aberrant expressions of p14ARF, MDM2, and p53 were observed in 19.6% (31/158), 47.5% (75/158), and 39.9% (63/158) of cases, respectively. The expression of MDM2 was significantly higher in borderline tumors compared to benign (P= 0.04) and malignant (P < 0.01) tumors. p53 expression in borderline tumors was uncommon, and p14ARF expression loss was mainly observed in carcinomas. Altered expression of p14ARF, MDM2, and p53 shows significant relationship with stage. Overexpression of MDM2 (P= 0.01) and loss of p14ARF expression (P= 0.04) were significantly associated with ER expression. Our results suggest that alteration of p14ARF-MDM2-p53 pathway proteins may contribute significantly to the tumorigenesis of ovarian serous neoplasms, and ER is involved in cellular regulation of p14ARF-MDM2-p53 pathway in ovarian serous neoplasms.

Characterization of CSOC 882, a novel immortalized ovarian cancer cell line expressing EGFR, HER2, and activated AKT

OBJECTIVE

Only a small number of comprehensively characterized immortalized ovarian cancer cell lines are available for laboratory studies on ovarian cancer. We describe a new ovarian cancer cell line that arose from primary culture of a stage IC, grade III ovarian carcinoma, designated CSOC 882.

METHODS

We characterized CSOC 882 by karyotyping, growth modeling, immunohistochemical staining, immunoblotting, drug sensitivity testing, and xenografting in nude mice.

RESULTS

CSOC 882 possessed an abnormal tetraploid karyotype including loss of one copy of chromosomes 2, 17, 19, and 21, and deletion of 8p21. Growth of CSOC 882 was best modeled using the logistic growth equation revealing an average doubling time of 31 h. CSOC 882 cells expressed vimentin, cytokeratin, p53, BRCA1, EGF receptor, HER2, androgen receptor, estrogen receptor alpha, and progesterone receptor, while no evidence of estrogen receptor beta or factor VIII was observed. Some but not all CSOC 882 cells were positive for CA125 reflecting the primary tumor, which had patchy CA125 staining. Drug sensitivity assays demonstrated that CSOC 882 was more sensitive to cisplatin and carboplatin than SKOV3 and HCC1937 while CSOC 882 and SKOV3 were both sensitive to paclitaxel unlike HCC1937. CSOC 882 xenografts retained the original characteristics of vimentin, cytokeratin, and factor VIII labeling.

CONCLUSIONS

CSOC 882 is an immortalized cell line that has survived more than 130 passages in culture and retained molecular features of the primary tumor from which it was derived. Compared to the most common ovarian carcinoma cell lines, CSOC 882 is a unique resource for genetic and cellular research on ovarian cancer.

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.