Objectives To investigate a family of cancer-testis antigens as biomarkers for early-stage ovarian cancer and whether they can be identified through non-invasive screening methods. We also aimed to examine the role of these cancer-testis antigens in disease progression.

Methods Manipulation of gene expression in ovarian cancer cell lines through plasmid and small interfering RNA transfection and immunocytochemistry of ovarian cancer stage I-IV tissue arrays.

Results Previously it has been shown that OCP2 is expressed at a significantly higher frequency in stage I (n=164) and II (n=15) ovarian cancer tissue arrays than current clinically used biomarkers CA-125, HE4 and WT1. Analysis of ovarian cancer cell lines has shown that other family members, OCP3 and 4, are expressed at higher intensities than OCP2. Silencing of these genes in ovarian cancer cells lead to phenotypical changes followed by cell death observed within 24 hours. In addition, overexpression of these genes increases cell proliferation.

Conclusions This data provides a foundation for further investigation into OCPs as biomarkers for early-stage ovarian cancer in patient blood, urine and tissue. The small size of the proteins may allow them to be excreted and therefore applicable for non-invasive screening. The function of these proteins could also make them candidates for targeted immunotherapy.