Expression of the chromatin remodeling factor Rsf-1 is upregulated in ovarian carcinoma effusions and predicts poor survival

doi:10.1016/j.ygyno.2006.05.042

Gynecologic Oncology

Volume 103, Issue 3, December 2006, Pages 814-819

https://doi.org/10.1016/j.ygyno.2006.05.042 Get rights and content

Abstract

Objective.

We recently identified Rsf-1, a chromatin remodeling gene, as a potential oncogene that is frequently amplified and overexpressed in ovarian serous carcinoma. However, its clinical role in ovarian cancer effusions is not clear. In the present study, we assessed the clinical significance of Rsf-1 overexpression in ovarian carcinoma effusions.

Methods.

Formalin-fixed paraffin-embedded sections from 168 effusions (134 peritoneal, 34 pleural) were analyzed for Rsf-1 expression using immunocytochemistry. Matched primary tumors (n = 48) and solid metastases (n = 73) from 48 patients were additionally studied. Rsf-1 expression in tumor cells in effusions was analyzed for possible association with clinicopathologic parameters and survival.

Results.

Rsf-1 protein expression was found in carcinoma cells in 157/168 (93%) effusions. Of these, 70 (45%) stained weakly and 87 (55%) strongly. Specimens from patients diagnosed with FIGO stage IV disease had higher staining score (extent × intensity) compared with stage III tumors (P = 0.008). Rsf-1 expression level was significantly lower in primary tumors and solid metastases (P < 0.001 for extent, intensity and score). Univariate survival analysis for 59 patients with post-chemotherapy recurrence effusions demonstrated a significant association between higher Rsf-1 staining and shorter overall survival (OS; P = 0.009 for staining extent and intensity, P = 0.02 for staining score). FIGO stage was the only clinical parameter associated with OS in this group (P = 0.032). In Cox analysis, Rsf-1 expression (P = 0.022 for staining extent and intensity, P = 0.045 for staining score) and FIGO stage (P = 0.035) were independent predictors of shorter survival.

Conclusions.

Rsf-1 is frequently expressed and upregulated in ovarian carcinoma cells in effusions and is a novel prognostic marker for patients with post-chemotherapy recurrent disease. The above findings support a role of Rsf-1 in mediating disease progression and aggressive clinical behavior in this subset of ovarian carcinoma patients.

Introduction

Ovarian carcinoma is the most lethal gynecologic cancer and currently ranks as the fifth in causing cancer-related deaths among women [1]. The major difficulty in achieving cure of ovarian carcinoma is the fact that the majority of patients are diagnosed with advanced-stage (FIGO III–IV) disease, thereby impeding efforts directed at surgical removal of all tumor burden. Another significant problem is that research has focused on studying the molecular characteristics of primary tumors, lesions that are amenable to surgical removal in the majority of cases, rather than metastatic cells in the peritoneal and pleural cavities, the most common site of dissemination and recurrence in ovarian carcinoma.

Identification and characterization of new cancer-associated genes will not only elucidate the pathogenesis of neoplastic diseases but also provide new diagnostic markers and therapeutic targets for cancer patients. In an effort to search for new amplified tumor-associated genes, we have previously applied a genome-wide technology, digital karyotyping [2], to identify novel amplicons that may harbor new potential oncogenes in ovarian cancer. Using digital karyotyping, we recently identified amplification at the 11q13.5 chromosome region and overexpression of the chromatin remodeling gene Rsf-1 (HBXAPα) that is localized to the amplicon in high-grade ovarian carcinoma [3]. Analysis of Rsf-1 amplification using FISH in primary tumors and of Rsf-1 mRNA levels in effusions using quantitative real-time PCR showed that its amplification and overexpression are associated with poor survival in both cohorts [3]. In that study, we also demonstrated a positive association between Rsf-1 gene amplification and immunointensity. In the present study, we analyzed the clinical role of Rsf-1 protein expression in a large cohort of ovarian carcinoma patients with malignant effusions using immunocytochemistry. The new data lend further support to the association between Rsf-1 expression and aggressive clinical behavior in this disease and provide evidence that Rsf-1 immunostaining can be a valuable tool to assess Rsf-1 expression and its relationship with the clinical outcome in the subset of ovarian carcinoma patients with disease recurrence effusions.

Section snippets

Study cohort

Specimens and relevant clinical data were obtained from the Department of Gynecologic Oncology, Norwegian Radium Hospital (Table 1). Informed consent was obtained according to national Norwegian and institutional guidelines. One hundred and sixty-eight fresh non-fixed malignant peritoneal (n = 134, 80% of specimens) and pleural (n = 34, 20% of specimens) effusions were obtained from 121 patients diagnosed with epithelial (predominantly serous) ovarian carcinoma (151 effusions, 90%), 4 patients

Results

Rsf-1 immunoreactivity was detected in carcinoma cells in 157/168 (93%) effusions. Of these, 70 (45%) stained weakly and 87 (55%) stained strongly (Figs. 1A to C). The percentage of Rsf-1 positive cells in the 157 specimens was as follows: 1–5%: 14 specimens (9%); 6–25%: 15 specimens (10%); 26–75%: 51 specimens (32%); 76–100%: 77 specimens (49%). Cancer cells in a given specimen tended to have a generally homogenous staining intensity. Inflammatory cells (lymphocytes and macrophages) and

Discussion

As in other cancer types, gene amplification is one of the major mechanisms mediating oncogene activation and thereby dysregulated growth in ovarian cancer. Chromosomal regions that have been shown to be amplified in cell lines or clinical specimens of ovarian carcinoma include 17q21–23 [8], 19q13.1–q13.2 [9], 3q26, 8q24 and 20q13 [10] or 20q12–13 [11]. Specific genes that have been reported as amplified in ovarian cancer are Ki-ras [12], HER2/neu [13], [14], INT-2 [14], AKT2 [15], cyclin E [16]

Acknowledgments

We gratefully acknowledge the competent technical help of Mrs. Inger-Liv Nordli, Mrs. Mai Nguyen and Mrs. Ann Larsen at the Department of Pathology, Norwegian Radium Hospital in performing the immunohistochemical analysis.

Financial acknowledgement: this study was supported in part by National Cancer Institute grant (RO1 CA103937).

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Previous research showed that Rsf-1 amplification exists in ovarian cancer and significantly correlates with the prognosis of patients. Depletion of Rsf-1 can reduce the proliferation ability of ovarian cancer cells, suggesting that it may be used as a marker of malignant tumor behavior in ovarian cancers [1,2]. Rsf-1 overexpression was also observed in breast cancer [3].
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Expression of the chromatin remodeling factor Rsf-1 is upregulated in ovarian carcinoma effusions and predicts poor survival

Abstract

Objective.

Methods.

Results.

Conclusions.

Introduction

Section snippets

Study cohort

Results

Discussion

Acknowledgments

Gynecol. Oncol.

Cancer Genet. Cytogenet.

Eur. J. Cancer

Am. J. Pathol.

Cell

Biochem. Biophys. Res. Commun.

Curr. Opin. Genet. Dev.

J. Biol. Chem.

Genomics

Gynecol. Oncol.

Hum. Pathol.

Gynecol. Oncol.

Clin. Lab. Med.

Digital karyotyping

Proc. Natl. Acad. Sci. U. S. A.

Amplification of a chromatin remodeling gene, Rsf-1/HBXAP, in ovarian carcinoma

Proc. Natl. Acad. Sci. U. S. A.

Detection of cancer cells in effusions from patients diagnosed with gynaecological malignancies. Evaluation of five epithelial markers

Virchows Arch.

The role of Desmin and N-cadherin in effusion cytology: a comparative study using established markers of mesothelial and epithelial cells

Am. J. Surg. Pathol.

Functional analysis of the subunits of the chromatin assembly factor RSF

Mol. Cell. Biol.

Comparative genomic hybridization detects frequent overrepresentation of chromosomal material from 3q26, 8q24, and 20Q13 in human ovarian carcinomas

Genes Chromosomes Cancer