Mouse anti Human BRCA1 antibody, clone MS13 recognizes the human tumor suppressor protein BRCA-1, also known as Breast cancer type 1 susceptibility protein or RING finger protein 53. BRCA1 is a 1863 amino acid, ~220 kDa E3 ubiquitin-protein ligase playing a central role in DNA repair (Tibbetts et al. 2000), expressed in the nucleus during the S/G2 phase of the cell cycle (Durrant and Nickoloff 2005). Normal BRCA-1 acts as a tumor suppressor protein and mutation or dysregulation of BRCA1 may indicate high risk of development of disease, including breast cancer (Budhram-Mahadeo et al. 1999). Mouse anti human BRCA-1, clone MS13 recognizes an epitope within the 304 amino acid N-Terminal (NT) region (Yoshikawa et al. 1999) of human BRCA1.

BRCA1 is expressed numerous organs including mammary and ovarian tissues (Miki et al. 1994) . Mutations in the BRCA-1 gene are associated with hereditary breast and ovarian cancers, particularly at a younger age of diagnosis. Women carrying BRCA1 mutations have a 50-95% chance of developing breast cancer in later life (Elit 2001), secondary cancers such as prostate or melanoma also frequently arise in the latter stages of both male and female breast cancer patients (Benevento et al. 2012), but genetic screening and increased awareness of preventative surgery, can reduce this risk significantly (Scheuer et al. 2002). However, in males pancreatic and prostate cancer appear to be more strongly associated with BRCA2 gene mutations (Gallagher et al. 2010).

BRCA1 is a key marker of triple-negative breast cancer (TNBC), a high risk aggressive cancer which makes up about 15% of invasive breast cancers, and lacks the benefit of specific targeted therapy (Duffy et al. 2012). Triple-negative tumors are predominantly basal-like, poorly differentiated and of higher histological grade. Younger women have an increased rate of basal or BRCA related TNBC, compared with the higher proportion of apocrine, normal-like and rare subtypes of TNBC, seen in older women (Liu et al. 2009).

Studies looking at sporadic breast cancer, have shown that clone MS13 strongly correlates with poor patient prognosis, and appears to label the Δ11b splice variant of BRCA1, suggesting that Δ11b could act as a negative marker in the prognosis of sporadic breast cancer (Fraser et al. 2003).

Mouse anti human BRCA1 antibody, clone MS13 is suitable for use in the immunohistochemical staining of human breast (Fraser et al. 2003) and for immunofluorescence in multiple cell lines (Scully et al. 1996).

This product has been reported to work in the following applications. This information is derived from testing within our laboratories, peer-reviewed publications or personal communications from the originators. Please refer to references indicated for further information. For general protocol recommendations, please visit the antibody protocols page.

Application Name	Verified	Min Dilution	Max Dilution
Immunofluorescence			1/500
Immunohistology - Paraffin			1/50
Immunoprecipitation
Western Blotting			0.5ug/ml

Histology Positive Control Tissue

Breast carcinoma

Western Blotting

Mouse anti Human BRCA1 detects a band of approximately 220kDa in HeLa nuclear extract. Some cell lysates may also show an uncharacterized band of approximately 65kDa.