Identification and Immunohistochemical Characterization of a Mucin-Like Glycoprotein Expressed in Early Stage Breast Carcinoma

Abstract

In this report we describe a cDNA sequence, BS106, identified from Incyte Genomics LifeSeq^® Expressed Sequence Tag database. A multi-tissue mRNA expression array, northern blots, and RT-PCR assays demonstrate the expression of BS106 in mammary, salivary and prostate glands, but not in other tissue types. BS106 mRNA was detected in 90% of the breast tissues examined. The cDNA encodes a 90-amino acid protein characterized as a small, mucin-like protein based on amino acid composition, extensive O-linked glycosylation, and expression profile. BS106 protein was recombinantly expressed in human embryonic kidney 293 cells and the secreted product was purified from the culture media. Monoclonal antibodies were prepared and used for immunohistochemical analysis of early stage breast cancer. BS106 protein was detected in the vast majority of carcinomas (70–100%) and overexpressed in approximately 30% of the 22 specimens analyzed. BS106 protein was not detected in other solid tumor types including bladder carcinoma, colon carcinoma, endometrial carcinoma, gastric carcinoma, squamous cell lung carcinoma, adenocarcinoma of the lung, ovarian carcinoma, pancreatic and prostatic carcinoma.

Diagnostic accuracy of small breast epithelial mucin mRNA as a marker for bone marrow micrometastasis in breast cancer: a pilot study

“…In mammary tissues, including breast cancer, SBEM expression has been shown to be restricted to luminal epithelial cells (Allinen et al 2004). Although SBEM expression has been found in the ER-positive, well-differentiated, ''luminal epithelial-like'' breast cancer cell lines (Lacroix and Leclercq 2004), other studies have shown SBEM gene expression, as assessed by RT-PCR, in more than 90% of primary or metastatic breast cancers (Miksicek et al 2002;Colpitts et al 2002;Brown et al 2006). In a small subset of primary breast tumours Skliris et al (2008) have recently shown that SBEM mRNA was detected by RT-PCR in all cases.…”

“…AF414087] was identified by Miksicek et al (2002) using the cDNA xProfiler tool. SBEM product is similar to proteins B511 s (Houghton et al 2001) and BS106 (Colpitts et al 2002). The SBEM gene is predicted to code for a low molecular weight glycoprotein with highly similarity to sialomucins, including MUC1.…”

Serological identification of breast cancer-related antigens from aSaccharomyces cerevisiae surface display library

“…46 SBEM protein could not be detected so far in other solid tumor types including bladder carcinoma, colon carcinoma, endometrial carcinoma, gastric carcinoma, squamous cell lung carcinoma, adenocarcinoma of the lung, ovarian carcinoma, pancreatic and prostatic carcinoma. 35 The SBEM variant detected in the present analysis lacks 1 of 3 mucin-characteristic tandem repeats and might show, compared to the known SBEM protein, a different glycosylation pattern. For other members of the mucin family, however, it is known that variations in the number of tandem repeats occur frequently.…”

“…32 Sixteen clones (C 4, 6-12, 14, 17, 19, 21-23, 26, 27, 31, 32) have been described already in the literature as being linked to carcinogenesis with at least 7 of them (C 8, 10, 11, 14, 22, 23, 32) having a strong association with breast cancer. [33][34][35][36][37][38] Two of seven breast cancer-related cDNA fragments (thymosin beta 10 and protein disulfide isomerase) were only recognised by patient serum and not by any control serum. Overexpression or altered expression in breast cancer tissue has been reported for both.…”

Use of a Panel of Novel Genes for Differentiating Breast Cancer from Non-Breast Tissues

“…Previous findings also suggested that expression of SBEM was mostly restricted to breast tissue [15,16] . However, unlike both MGA and B726P but in agreement with previous findings [15,16] , expression of SBEM was independent of ER status and tumour grade in our study.…”