Elevated expression of cancer/testis antigen FSIP1 in ER-positive Breast Tumors

Abstract

Aim: The study aimed to identify and characterize highly specific breast tumor biomarkers. Methods: A microarray data set comprised of 513 diverse normal and tumor mRNA samples was analyzed to identify breast tumor biomarkers with minimal expression in normal tissues. Results:FSIP1 was identified as a breast tumor biomarker with elevated mRNA expression in breast tumors and minimal expression in most normal tissues except the testis. Quantitative real-time PCR confirmed the elevated expression of FSIP1 mRNA in breast tumors and revealed a significant correlation with ER-positive status. Immunofluorescence staining of breast tumor sections showed that the majority of breast tumors examined in this study (20 out of 22) expressed detectable FSIP1 protein, with significantly higher than average expression in ER-positive versus ER-negative breast tumors. Conclusion: The prevalence and uniformity of FSIP1 expression in breast tumors, taken together with the highly restricted expression in normal tissues, suggests that FSIP1 may be an attractive target for breast cancer immunotherapy.

KEYWORDS::

• biomarker
• breast cancer
• cancer immunotherapy
• cancer/testis antigen
• cancer vaccine
• FSIP1

Supplementary Material

Acknowledgements

The authors would like to thank A Becker and K Beckman (Biomedical Genomics Center, University of Minnesota, MN, USA) for performing the Illumina microarray. The authors would also like to thank R Edgar and I Lieder for comments on the manuscript.

Financial & competing interests disclosure

This study was funded by OncoCyte Corporation (CA, USA). KB Chapman, MJ Prendes, JL Kidd and J Wagner are employees of OncoCyte Corporation; MD West and H Sternberg are employees of BioTime, Inc. (CA, USA). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from the disclosed.

Writing assistance was provided by AJ Petersen and was funded by OncoCyte Corporation.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Additional information

Funding

This study was funded by OncoCyte Corporation (CA, USA). KB Chapman, MJ Prendes, JL Kidd and J Wagner are employees of OncoCyte Corporation; MD West and H Sternberg are employees of BioTime, Inc. (CA, USA). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from the disclosed.