Human Small Breast Epithelial Mucin: The Promise of a New Breast Tumor Biomarker

Abstract

Breast cancer remains one of the most frequently diagnosed cancers today. In developed countries, one in eight women is expected to present with breast cancer within her lifetime and an estimated 1,000,000 cases are detected each year worldwide (Canadian Cancer Statistics, http://www.cancer.ca/vgn/images/ portal/cit_86751114/14/33/1959864 11niw_stats2004_en.pdf). For women with recurrent disease, the median time of survival is about 2 years. Despite optimal surgery, adjuvant irradiation, hormonal treatment, and chemotherapy, approximately 30% of patients with localized breast cancer finally develop distant metastases. Early detection, which enables intervention at a localized and potentially curable stage, remains a central goal in breast cancer treatment. Indeed, the 5-year survival rate for women with breast cancer has been shown to increase dramatically when the disease is diagnosed at an early stage: from less than 25% in women with disseminated cancer to about 75% in patients with regional disease and over 95% in women with a localized tumor (Breast Cancer Facts and Figures, 2001-2002, http://www.cancer.org/downloads/STT/BrCaFF 2001.pdf). Unfortunately, only 60% of all breast cancers are diagnosed at a local stage. Any improvement in early detection through identification of tumor biomarkers would have a significant impact on reducing overall breast cancer mortality.

Small breast epithelial mucin promotes the invasion and metastasis of breast cancer cells via promoting epithelial‑to‑mesenchymal transition

“…Patients with isolated tumor cells or micrometastases have a comparably poor 5-year disease-free survival rate (16). Detection of breast cancer micrometastases based on specific molecular markers and exploration of the potential underlying mechanism may provide useful information for clinical research (17). Small breast epithelial mucin (SBEM) is a type of secretory protein, which belongs to the family of MUC (18).…”

Small breast epithelial mucin (SBEM) has the potential to be a marker for predicting hematogenous micrometastasis and response to neoadjuvant chemotherapy in breast cancer

“…The small breast epithelial mucin (SBEM) gene, also known as BS106 and/or B511S, was originally identified as a putative breast-specific gene and was considered to be an attractive candidate for breast tumor marker. [9,21]. Skliris et al [14] investigated SBEM expression by IHC in TAMs and its association with other established markers of prognosis and concluded that SBEM could identify a unique subset of breast cancers with poor prognosis.…”

Adeno-associated virus type 2 infection activates caspase dependent and independent apoptosis in multiple breast cancer lines but not in normal mammary epithelial cells

“…Breast cancer is also the most frequent cancer of women (23% of all cancers) [1]. Routine screening and early detection have reduced the incidence of breast cancer, but despite optimal treatment, about 30% of women with recurrent disease develop distant metastases [3]. Although multiple chemotherapeutic strategies are currently in use for the treatment of breast cancer [4], active treatment of patients is determined by multiple factors such as the hormone-dependency of the cancer [5], activation of specific oncogenes [6], invasiveness and metastases [7], subsequent drug resistance [8-10] and the risk of potential toxicities with repeated therapy [4,11].…”