Assessment of stanniocalcin-1 mRNA as a molecular marker for micrometastases of breast cancer

Very few tumor molecular markers have been identified that are highly specific for breast cancer cells when applied to blood. Stanniocalcin [STC]-1 is a recently discovered human gene that has been implicated in cellular calcium homeostasis and is located on chromosome 8p in a region associated with amplification of breast cancer. We investigated STC-1 mRNA as a molecular marker for detecting occult breast cancer cells in blood. Using real time PCR detection assay to assess for STC-1 mRNA expression, we evaluated the blood of 25 breast cancer patients with different stages [I-IV] according to American Joint Committee on Cancer, 7 patients with benign breast lumps as fibroadenomas and fibrocystic swelling, and 8 healthy women as control subjects. In this study there was blood STC-1 gene expression of the malignant group; the mean value of the STC-1 positive blood specimen [copies number] was 8103.1+491.0, without blood expression in the other two groups. Also, the results of this work showed that, 19 [76%] patients of 25 patients of cancer breast had detectable STC-1 mRNA [copies] in their blood, without detectable expression in the other 6 [24%], p<0.001 with significant increase of STC-1 copy numbers with progression of AJCC stages, P<0.001. Finally in this study, the presence of STC-1 mRNA in the blood significantly correlated with primary tumor size [P<0.001], the involved lymph nodes characteristics [P<0.001], the presence of distant metastasis [P<0.001] and the overall AJCC stage [P<0.001]. STC-1 mRNA assay may be a useful and sensitive molecular marker for breast cancer cases with different stages without expression in the normal blood cells. Also, the presence of breast cancer associated STC-1 mRNA in the blood cells correlated significantly with the primary clinico-pathological determinants of disease outcome