Characterization of a putative ovarian oncogene, elongation factor 1alpha, isolated by panning a synthetic phage display single-chain variable fragment library with cultured human ovarian cancer cells.

PURPOSE: In an effort to identify cell surface targets and single short-chain antibody (scFv) for ovarian cancer therapy, we used a phage display approach to isolate an antibody with high reactivity against ovarian cancer. EXPERIMENTAL DESIGN: A phage scFv library was subjected to panning against human SK-OV-3 ovarian cancer cells. A clone with high reactivity was selected and tested in immunoperoxidase staining on a panel of normal tissues and ovarian carcinoma. Using immunoprecipitation, a differentially expressed band was analyzed by mass spectrometry. The antigen subclass was characterized with reverse transcription-PCR on cDNA library of normal tissues, and 91 ovarian cancer specimens, and correlated with clinicohistopathologic characteristics. RESULTS: Ninety-six individual scFv clones were screened in ELISA following panning. scFv F7 revealed high reactivity with ovarian cancer cell lines and showed intense staining of 15 fresh ovarian cancer specimens and no staining of a panel of normal tissues. A 40-kDa protein was identified to be translation elongation factor 1alpha1 (EEF1A1; P < 0.05). The expression of EEF1A2, a highly homologous and functionally similar oncogene, was found to be restricted only to the normal tissues of the heart, brain, and skeletal muscle. Aberrant EEF1A2 mRNA expression was found in 21 of 91 (23%) of ovarian cancer specimens and significantly correlated with increased likelihood of recurrence (P = 0.021). CONCLUSIONS: scFv F7 may represent an ovarian cancer-specific antibody against translation EEF1A family of translational factors. We propose that EEF1A2 may be a useful target for therapy of human ovarian cancer.

OY-TES-1 expression and serum immunoreactivity in epithelial ovarian cancer.

OY-TES-1 is a novel target that belongs to the family of 'cancer/testis' (CT) antigens. Our goal was to examine the expression and immunogenicity of OY-TES-1 in epithelial ovarian cancer (EOC) to determine its potential as a target for vaccine therapy. OY-TES-1 expression was determined by one-step reverse transcriptase PCR on 100 EOC samples, 5 EOC cell lines, and a panel of normal tissues. Immunohistochemistry (IHC) was performed on the same panel of EOC tissues. Sera from a sub-group of patients were tested for OY-TES-1 antibody by ELISA. Thymus and leukocytes were weakly positive for OY-TES-1 while the remaining 5 normal tissues were negative. Expression of OY-TES-1 by either RT-PCR and/or IHC was demonstrable in 69/100 (69%) tumors. Humoral immunity to OY-TES-1 was demonstrated in 1/10 (10%) serum samples from patients whose tumors expressed the antigen. The median follow-up of the patient population was 34 months. There was no correlation between antigen expression and stage, grade, histology and survival. OY-TES-1 is expressed in 69% of patients with EOC, is absent from normal ovarian tissue, and a proportion of patients show evidence of a specific humoral immune response. These findings make OY-TES-1 an attractive target for antigen-specific immunotherapy in EOC.

Detection of epithelial ovarian cancer using 1H-NMR-based metabonomics.

Currently available serum biomarkers are insufficiently reliable to distinguish patients with epithelial ovarian cancer (EOC) from healthy individuals. Metabonomics, the study of metabolic processes in biologic systems, is based on the use of (1)H-NMR spectroscopy and multivariate statistics for biochemical data generation and interpretation and may provide a characteristic fingerprint in disease. In an effort to examine the utility of the metabonomic approach for discriminating sera from women with EOC from healthy controls, we performed (1)H-NMR spectroscopic analysis on preoperative serum specimens obtained from 38 patients with EOC, 12 patients with benign ovarian cysts and 53 healthy women. After data reduction, we applied both unsupervised Principal Component Analysis (PCA) and supervised Soft Independent Modeling of Class Analogy (SIMCA) for pattern recognition. The sensitivity and specificity tradeoffs were summarized for each variable using the area under the receiver-operating characteristic (ROC) curve. In addition, we analyzed the regions of NMR spectra that most strongly influence separation of sera of EOC patients from healthy controls. PCA analysis allowed correct separation of all serum specimens from 38 patients with EOC (100%) from all of the 21 premenopausal normal samples (100%) and from all the sera from patients with benign ovarian disease (100%). In addition, it was possible to correctly separate 37 of 38 (97.4%) cancer specimens from 31 of 32 (97%) postmenopausal control sera. SIMCA analysis using the Cooman's plot demonstrated that sera classes from patients with EOC, benign ovarian cysts and the postmenopausal healthy controls did not share multivariate space, providing validation for the class separation. ROC analysis indicated that the sera from patients with and without disease could be identified with 100% sensitivity and specificity at the (1)H-NMR regions 2.77 parts per million (ppm) and 2.04 ppm from the origin (AUC of ROC curve = 1.0). In addition, the regression coefficients most influential for the EOC samples compared to postmenopausal controls lie around delta3.7 ppm (due mainly to sugar hydrogens). Other loadings most influential for the EOC samples lie around delta2.25 ppm and delta1.18 ppm. These findings indicate that (1)H-NMR metabonomic analysis of serum achieves complete separation of EOC patients from healthy controls. The metabonomic approach deserves further evaluation as a potential novel strategy for the early detection of epithelial ovarian cancer.

SCP-1 cancer/testis antigen is a prognostic indicator and a candidate target for immunotherapy in epithelial ovarian cancer.

SCP-1 is a novel tumor antigen that belongs to the growing family of cancer/testis (CT) antigens, and it is a potential target for immunotherapy. In an effort to determine the expression of SCP-1 in epithelial ovarian cancer (EOC), one-step RT-PCR was performed with RNA from epithelial ovarian tumor tissues and with two normal ovarian surface epithelial cell lines. We used immunohistochemistry (IHC) to investigate SCP-1 expression in paraffin-fixed EOC samples and ELISA to test sera from a subgroup of patients for SCP-1 antibody. SCP-1 was expressed in 15 out of 100 (15%) primary tumors, as determined by RT-PCR. The normal ovarian surface epithelial cell lines were negative for SCP-1 expression, as were a panel of other normal tissues. None of the patients whose tumors were determined to be SCP-1 positive by RT-PCR expressed the antigen by IHC or demonstrated a humoral immune response by ELISA. Tumors that expressed SCP-1 mRNA tended to have a higher grade than those that did not (P = 0.03). There was a significant decrease in survival time (P = 0.004) for patients with SCP-1 mRNA-positive tumors compared to those with SCP-1 mRNA-negative tumors [median 25 mo, 95% confidence interval (CI) 0-56 mo; and median 97 mo, CI 32-162 mo, respectively]. The present study shows that SCP-1 mRNA expression in patients with EOC is associated with a poorer chance of survival. These findings imply that further evaluation of SCP-1 as a potential target for vaccine therapy in EOC is warranted.

New modalities in detection of recurrent ovarian cancer.

PURPOSE OF REVIEW: The vast majority of women diagnosed with ovarian cancer and subsequently treated with debulking surgery and adjuvant chemotherapy will ultimately relapse. As is the case with primary diagnosis, detection of recurrent ovarian cancer is limited due to lack of sensitivity and specificity. Specific guidelines for surveillance of this disease are controversial, partly because evidence to support such guidelines is scant and partly because the management of identified recurrences continues to be of minimal success. Subsequently, whether early detection actually can make a difference is not necessarily made clear in the literature. However, there are advances in radiological and molecular biology technology that may offer new possibilities in cancer surveillance. This review will outline the latest evidence to address their use in ovarian cancer. RECENT FINDINGS: Most of the recent literature involving detection of recurrent ovarian cancer addresses the use of positron emission tomography. There are also some data addressing the use of magnetic resonance imaging and computed tomography in this arena. Data pertaining to other modalities such as biological markers are limited. Ca-125 is the accepted assay used for ovarian cancer surveillance, but other options are introduced that may hold promise for the future. SUMMARY: A review of the recent literature concerning ovarian cancer surveillance techniques offers few new definitive avenues. While radiological technology and discoveries in detection assays are noteworthy, their potential impact on surveillance appears to be minimal at this time. Low sensitivity and specificity, along with expense, continue to be limiting factors.

NY-ESO-1 and LAGE-1 cancer-testis antigens are potential targets for immunotherapy in epithelial ovarian cancer.

Cancer-testis (CT) antigens are expressed in a variety of cancers, but not in normal adult tissues, except for germ cells of the testis, and hence appear to be ideal targets for immunotherapy. In an effort to examine the potential of NY-ESO-1 and LAGE-1 CT antigens for immunotherapy in epithelial ovarian cancer (EOC), we examined the expression of these antigens by reverse transcription-PCR (RT-PCR) and immunohistochemistry (IHC) in a large panel of EOC tissues and cell lines. Sera from a subgroup of the patients were tested for NY-ESO-1/LAGE-1 antibody by ELISA. The data indicated that four ovarian cancer cell lines were positive for one or both CT antigens. Expression of NY-ESO-1 in EOC was demonstrated by RT-PCR and/or IHC in 82 of 190 (43%) specimens. NY-ESO-1 expression by IHC ranged from homogeneous to heterogeneous pattern. LAGE-1 mRNA expression was present in 22 of 107 (21%) tumor tissues. Overall, the expression of either NY-ESO-1 or LAGE-1 mRNA was present in 42 of 107 (40%) EOC specimens and coexpression of both antigens was demonstrated in 11% of specimens. Antibody to NY-ESO-1/LAGE-1 was present in 11 of 37 (30%) patients whose tumors expressed either NY-ESO-1 or LAGE-1. Detectable antibodies were present for up to 3 years after initial diagnosis. Although there was no statistically significant relation between expression of NY-ESO-1/LAGE-1 antigen and survival, the data showed aberrant expression of NY-ESO-1 and LAGE-1 by IHC/RT-PCR in a significant proportion of EOC patients. These findings indicate that NY-ESO-1 and LAGE-1 are attractive targets for antigen-specific immunotherapy in EOC.