Stanniocalcin-1: a novel molecular blood and bone marrow marker for human breast cancer.

PURPOSE Very few tumor molecular markers have been identified that are highly specific for breast cancer cells when applied to blood and bone marrow (BM). Stanniocalcin (STC)-1 is a recently discovered human gene that has been implicated in cellular calcium homeostasis and resistance to hypoxia and is located on chromosome 8p in a region associated with amplification in breast cancer. We investigated STC-1 mRNA as a potential molecular marker for detection of breast cancer metastasis in the blood and BM. EXPERIMENTAL DESIGN Using the reverse transcriptase-PCR and electrochemiluminescence detection assay to assess for STC-1 mRNA expression, we evaluated 7 breast cancer cell lines, 34 primary breast cancer tumors, and the BM of 71 patients and the blood of 58 patients with American Joint Committee on Cancer stage 0-IV breast cancer. RESULTS In this cohort of primarily early-stage breast cancer patients, the detection of STC-1 mRNA in the BM and blood significantly correlated with multiple histopathological prognostic factors, including primary tumor size, number of positive lymph nodes, T stage, M stage, N stage, and overall American Joint Committee on Cancer stage. STC-1 mRNA was not detected in the blood or BM of volunteers without cancer. In situ hybridization studies with a STC-1 antisense RNA probe also confirmed STC-1 mRNA expression in breast cancer cell lines and primary breast tumors. CONCLUSIONS STC-1 is proposed as a novel, specific, and clinically useful molecular marker for detecting occult breast cancer cells in the BM and blood.