Proteomic Profiling Identifies Afamin as a Potential Biomarker for Ovarian Cancer

Abstract

Purpose:To discover and validate serum glycoprotein biomarkers in ovarian cancer using proteomic-based approaches. Experimental Design: Serum samples from a ''discovery set''of 20 patients with ovarian cancer or benign ovarian cysts or healthy volunteers were compared by fluorescence two-dimensional differential in-gel electrophoresis and parallel lectin-based two-dimensional profiling.Validation of a candidate biomarker was carried out with Western blotting and immunoassay (n = 424). Results: Twenty-six proteins that changed significantly were identified by mass spectrometric sequencing. One of these, confirmed byWestern blotting, was afamin, a vitamin E binding protein, with two isoforms decreasing in patients with ovarian cancer. Validation using cross-sectional samples from 303 individuals (healthy controls and patients with benign, borderline, or malignant ovarian conditions and other cancers) assayed by ELISA showed significantly decreased total afamin concentrations in patients with ovarian cancer compared with healthy controls (P = 0.002) and patients with benign disease (P = 0.046). However, the receiver operating characteristic areas for total afamin for the comparison of ovarian cancer with healthy controls or benign controls were only 0.67 and 0.60, respectively, with comparable figures for CA-125 being 0.92 and 0.88 although corresponding figures for a subgroup of samples analyzed by isoelectric focusing for afamin isoform 2 were 0.85 and 0.79. Analysis of a further 121 samples collected prospectively from 9 patients pretreatment through to relapse indicated complementarity of afamin with CA-125, including two cases in whom CA-125 was noninformative. Conclusions: Afamin shows potential complementarity with CA-125 in longitudinal monitoring of patients with ovarian cancer, justifying prospective larger-scale investigation. Changes in specific isoforms may provide further information.

Comparative secretome of ovarian serous carcinoma: Gelsolin in the spotlight

“…Despite the relatively small number of tissue and ascites specimens studied, the majority of proteins identified in the present study as being significantly differentially secreted from malignant and CTRL cell samples had been detected in previous studies (8)(9)(10)(11)(12)(13)(14)(15)(16), confirming their potent and important role. To the best of our knowledge, proteins including HSP-10 and DKK3, had not previously been identified by a proteomic approach, but had been suggested as potent markers using alternate approaches (19,30); however the present study was unable to confirm their utility as biomarkers of serous ovarian cancer by the immunological method.…”

“…Certain previous studies have analyzed the proteomic profiles of ovarian tumor tissues, cell lines, urine, ascites fluid and blood samples (8)(9)(10)(11)(12)(13)(14). Analysis of the ovarian cancer cell line secretome has also provided information on potential markers (11,15).…”

Plasma proteomic analysis of patients with squamous cell carcinoma of the uterine cervix

“…35,36 Wu et al 37 reported that afamin was significantly down-regulated in hepatoma tissue. Jackson et al 38 showed that afamin was decreased in the serum of ovarian cancer patients. In contrast, we found that afamin was significantly elevated in the plasma of patients with SCC of the cervix.…”

SPARC ectopic overexpression inhibits growth and promotes programmed cell death in acute myeloid leukemia transformed from myelodysplastic syndrome cells, alone and in combination with Ara-C treatment

“…ELP5 was initially identified as a component of a hyperphosphorylated RNA polymerase II (RNAPII) holoenzyme isolated from budding yeast chromatin and subsequently from human melanoma cells (26). AFM, one of the newest members of albumins, is considered a good prognosis marker in ovarian cancer (27)(28)(29). The mRNA expression levels of these genes were tested by qPCR to validate our microarray results.…”