Breast cancer biomarkers

Find the right cancer biomarker for your research using our cancer immunohistochemistry (IHC) guide to breast cancer

IHC is an increasingly common method used in the diagnosis of breast cancer and research into breast cancer pathology. There is an increasing number of antibodies available for the detection of breast cancer-specific markers. These markers are used to determine different breast cancer types, e.g. in situ or invasive carcinoma, distinguishing normal breast cell types e.g. luminal, basal and myoepithelial, and also proliferation and disease progression (Zaha et al., 2014).

Here we look at some of the most common primary IHC markers for breast cancer along with some cell type-specific markers and recommended antibodies for each biomarker in IHC.

Overview

• Primary IHC breast cancer biomarkers
• Cell-type-specific biomarkers

Cancer biomarker guide homepage

Primary IHC biomarkers

Estrogen receptor alpha

Determining the distribution of estrogen receptor alpha (ER-α) in breast cancer samples is an important initial step for the diagnosis and treatment evaluation of the disease (Hicks et al., 2017). Approximately 70% of breast cancer samples will give a positive staining signal for ER-α making it a crucial biomarker for breast cancer diagnosis (Jeselsohn et al., 2015). ER-α is a nuclear protein with a ligand-dependent transcription factor function. It is also most commonly detected in both luminal A and B subtypes of breast cancer (Jeselsohn et al., 2015).

^{Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) analysis of human breast ductal infiltrating carcinoma tissue labeling Estrogen Receptor alpha with unpurified ab108398.​}

IHC stain: nuclear stain
Recommended antibody: Recombinant Anti-Estrogen Receptor alpha antibody [EPR4097] - ChIP Grade (ab108398)

Progesterone receptor

The progesterone receptor (PR) is another biomarker important for the initial diagnosis and evaluation of breast cancer (Hicks et al., 2017). PR is known to be induced by ER-α and plays a key role in ER-α protein regulation. PGR as a biomarker is therefore commonly used as an indicator of ER-α function (Mohammed et al., 2015). PR is highly expressed in luminal A-type breast cancer tissue and is associated with a good prognosis (Lim et al., 2016). 

IHC stain: nuclear
Recommended antibody: Recombinant Anti-Progesterone Receptor antibody [YR85] (ab32085)

ErbB2/HER2

Overexpression of ErbB2/HER2 can be found in 20–30% of breast cancer tumors and is commonly found in more aggressive types of the disease (Mitri et al., 2012). ErbB2/HER2 is used as a diagnostic indicator for the FDA approved monoclonal antibody therapy, Trastuzumab (Herceptin). During this therapy ErbB2/HER2 acts as the binding target of Trastuzumab (Piccart-Gebhart et al., 2006). 

^{Formalin-fixed, paraffin-embedded human breast, invasive ductal carcinoma tissue stained for ErbB 2 using ab16662 at 1/200 dilution in immunohistochemical analysis, followed by Goat anti-Rabbit IgG HRP. Heat mediated antigen retrieval was done using a pH 8.5 buffer.}
​
IHC stain: cytoplasmic, nuclear, and strongly in the cell membrane
Recommended IHC antibody: Recombinant Anti-ErbB 2 antibody [SP3] (ab16662)

p53

Mutated versions of the tumor suppressor p53 can be found in 80% of triple-negative breast cancer (TNBC) cases, ie tumors lacking expression of ER, PR, and ErbB2/HER2 (Duffy et al., 2018). This makes mutant p53 an excellent biomarker for TNBC, one of the more difficult breast cancers to treat as it will not respond to endocrine or anti-HER2 treatments (Li et al., 2019). Currently, there are mixed findings on the prognostic potential of p53 expression in breast cancer. Some studies have associated it with a positive prognostic outcome and others negative. (Li et al., 2019). p53 IHC stains are commonly used for diagnostic purposes.

IHC stain: cytoplasm and strong nuclear
Recommended IHC antibody: ​Anti-p53 antibody [DO-1] - ChIP Grade (ab1101)

BRCA1

Mutations in the BRCA genes are some of the most well-known breast cancer-associated protein mutations. BRCA1 is a tumor suppressor gene and one of the most commonly mutated genes in breast cancer. Patients with a BRCA1 mutation have a 40–80% increased risk of developing the disease making it a crucial biomarker in the diagnosis and prognosis of many breast cancer types (Fackenthal et al., 2007). 

IHC stain: nuclear signal
Recommended IHC antibody: Anti-BRCA1 antibody [MS110] (ab16780)

Epidermal growth factor receptor (EGFR)

EGFR is a transmembrane receptor and its expression is frequently found in TNBC and inflammatory breast cancer (IBC). It is most commonly associated with a poor prognosis (Masuda et al., 2012). High levels of EGFR expression is linked to an increased ability of the breast cancer to undergo metastasis making it a common biomarker for aggressive breast cancer types (Ali et al., 2016).  

IHC stain: cytoplasm and strong nuclear
​Recommended IHC antibody: Anti-EGFR antibody [EP38Y] (ab52894)

CK20 (cytokeratin 20) and CK7 (Cytokeratin 7)

CK7 and CK20 are cytokeratins expressed in breast epithelia. Different CK7 and CK20 IHC expression patterns are commonly used to distinguish many carcinoma types including breast carcinomas. Most breast cancers are CK7 positive and CK20 negative, making the combination of these cytokeratins an excellent biomarker combination. Approximately 80% of breast adenocarcinomas are CK7 positive and CK20 negative (Chu et al., 2000). 

IHC stain: cytoplasm 
Recommended CK20 IHC antibody: Recombinant Anti-Cytokeratin 20 antibody [EPR1622Y] - Cytoskeleton Marker (ab76126)
​Recommended CK7 IHC antibody: Recombinant Anti-Cytokeratin 7 antibody [EPR1619Y] - Cytoskeleton Marker (ab68459)

APOBEC3B (apolipoprotein B mRNA editing catalytic polypeptide-like 3B)

APOBEC3B is expressed in ER-positive breast cancers and is used as a biomarker of poor prognosis for the disease and is a driver for downstream genetic mutations which accelerate the progression of breast cancer. These mutations make APOBEC3B positive breast cancers extremely drug-resistant (Zou et al., 2017). 

IHC stain: nuclear signal
Recommended IHC antibody: Anti-APOBEC3B antibody - N-terminal (ab191695)

Cyclin D1

Cyclin D1 is one of the main regulatory proteins of the cell cycle promoting the cell cycle progression from G1 to S phase. Mutations in cyclin D1 are amplified in many different types of cancer including many breast cancers. 50% of breast cancers will contain an overexpression of cyclin D1 (Mohammadizadeh et al., 2013). It has been used as a biomarker for poor prognosis for many breast cancer types, but some studies are beginning to suggest that it could also suggest a positive outcome if expressed in some luminal subtypes of breast cancer (Ortiz et al., 2017). 

IHC stain: nuclear
Recommended IHC antibody: IHC antibody: Recombinant Anti-Cyclin D1 antibody [EPR2241] - C-terminal (ab134175)

Ki67

Ki67 is an important protein involved in cell division and is commonly used as a marker of cellular proliferation. It is also used in breast cancer diagnosis to determine the level of cell proliferation which can be a prognostic marker and a good indication of well certain breast cancers will respond to endocrine therapy (Niazi et al., 2018). 

IHC stain: nuclear
Recommended IHC antibody: Anti-Ki67 antibody (ab15580)

Cyclooxygenase-2 (COX-2)

COX-2 is an enzyme responsible for producing prostanoids. Its expression in breast tissue correlates strongly with breast cancer development. Overexpression of COX-2 has been shown to drive breast cancer phenotypes and blocking the action of this protein also shows potential for breast cancer therapy. There is also a strong link between COX-2 overexpression in breast adipose tissue and cancer progression linked to obesity (Harris et al., 2014). 

IHC stain: cytoplasm
Recommended IHC antibody: Recombinant Anti-COX2 / Cyclooxygenase 2 antibody [EPR12012] (ab179800)

Caveolin-1

Caveolin-1 is the main component of caveolae, small invaginations found in the cell membrane. It’s also known to play a key role in cell proliferation, invasion, and breast cancer metastasis. It is also used as a biomarker for breast cancer treatments and disease outcome. High expression of caveolin-1 is a sign of poor prognosis an indicates are more aggressive metastatic breast cancer (Qian et al., 2019). 

IHC stain: cell membrane
Recommended IHC antibody: Recombinant Anti-Caveolin-1 antibody [E249] - Caveolae Marker (ab32577)

Peroxisome proliferator-activated receptor (PPAR-γ)

PPAR-γ is a well-studied nuclear hormone receptor. PPAR-γ has been implicated in different types of breast cancer in which its ligands inhibit proliferation and angiogenesis and induce apoptosis (Fenner et al., 2005). It has also been shown to play a role in promoting breast tumor growth through the maintenance of HER2 positive endothelial breast cancer stem cells making its expression a good biomarker for this cell type (Wang et al., 2013).

IHC stain: nuclear
​Recommended IHC antibody: Anti-PPAR gamma antibody - ChIP Grade (ab45036)

Cell-type-specific biomarkers

FOXA1

The transcription factor FOXA1 has been shown to have a unique distribution within breast cancer cells compared to other cell types. FOXA1 binding is crucial for chromatin opening and the transcriptional activation of ER-α responsive genes within breast cancer cells (Cowper-Sallari et al., 2012). Studies have identified thousands of breast cancer-associated single nucleotide polymorphisms (SNPs) within the enhancer regions for FOXA1 (Meyer et al., 2012). 

IHC stain: nuclear signal
Recommended IHC antibody: Recombinant Anti-FOXA1 antibody [EPR10881] (ab170933)

GATA-binding protein 3 (GATA3)

GATA3 is a zinc finger transcription factor crucial for breast luminal epithelium differentiation. It is also a diagnostic biomarker for both primary and metastatic breast cancer and commonly found in luminal A and B breast cancer tissue. GATA3 also has a strong association with HER2 positive and ER- α positive hormone response in luminal breast cancers (Shaoxian et al., 2017). 

IHC stain: nuclear signal
Recommended IHC antibody: Recombinant Anti-GATA3 antibody [EPR16651] - ChIP Grade (ab199428)

CK5 (Cytokeratin 5)

CK5 is a cytokine found to be expressed in the basal cell layer of the mammary duct. Tumors that arise from these cells are also known to be CK5 positive and so CK5 is an excellent biomarker for the diagnosis of basal type breast cancers. The CK5 positive progenitor cells may also differentiate into glandular and myoepithelial cancer types (Laakso et al., 2005).  

IHC stain: cytoplasm and cell membrane
Recommended IHC antibody: Recombinant Anti-Cytokeratin 5 antibody [EP1601Y] - Cytoskeleton Marker (ab52635)

Smooth muscle myosin heavy chain (SMMHC)

SMMHC is expressed specifically in the contractile myoepithelial cells of the breast. A loss of the myoepithelial layer is commonly associated with invasive breast cancers. Markers such as SMMHC can be used in IHC to detect this layer more reliably than a hematoxylin and eosin stain alone (Zaha et al., 2014). 

IHC stain: cytoplasm
Recommended IHC antibody: Recombinant Anti-smooth muscle Myosin heavy chain 11 antibody [EPR5336(B)] (ab133567)

E-cadherin

E-cadherin is expressed at the cell junction of normal breast epithelial cells. A loss of E-cadherin is associated with a phenotypic switch by these cells to become invasive and migratory breast cancer cells. Loss of E-cadherin expression is commonly used as a biomarker for metastatic lobular breast carcinomas (Singhai et al., 2011).

IHC stain: Cell junctions
Recommended IHC antibody: Recombinant Anti-E Cadherin antibody [EP700Y] - Intercellular Junction Marker (ab40772)

Alpha smooth muscle actin (ACTA2)

Smooth muscle actin is highly expressed in normal breast myoepithelial cells. It is commonly used as a marker of this normal breast cell type. Smooth muscle actin is commonly used for histology in conjunction with SMMHC and calponins to mark out the myoepithelial layer. A combination of markers such as this is much more reliable than using hematoxylin and eosin stains alone (Zaha et al., 2014).

IHC stain: cytoplasm
Recommended IHC antibody: Anti-alpha smooth muscle Actin antibody (ab5694)

Calponin

Calponins are proteins found within the contractile components of the myoepithelium. Similarly to SMMHC and ACTA2, calponin stains are used as a marker of the myoepithelial layer in the diagnosis of invasive breast cancers (Zaha et al., 2014). 

IHC stain: cytoplasm
Recommended IHC antibody: Recombinant Anti-Calponin 1 antibody [EP798Y] (ab46794), Anti-Calponin 2 antibody (ab129331), Anti-Calponin 3 antibody (ab151427)

Delta-1-Catenin

Delta-1-Catenin is a member of the p120 family and acts as a binder of E-cadherin. Delta-1-Catenin can be used in histology to detect invasive lobular breast cancer, high tumor-node-metastasis stage, and lymph node metastasis. It is also strongly associated with HER2 positive breast cancers and can be used as an indicator of poor prognosis as it is thought to promote a malignant phenotype (Zhang et al., 2015). 

IHC stain: cytoplasm and cell membrane
Recommended IHC antibody: Recombinant Anti-delta 1 Catenin/CAS antibody [EPR357(2)] (ab92514)

CK14 (Cytokeratin 14)

CK14 is a cytokine found to be expressed in the basal cell layer of the mammary duct. It is most commonly found to be co-expressing with CK5 is this tissue type and similarly to CK5, the histological detection of CK14 is an excellent biomarker for the diagnosis of basal type breast cancers (Laakso et al., 2005).

IHC stain: cytoplasm
Recommended IHC antibody: Recombinant Anti-Cytokeratin 14 antibody [EPR17350] - Cytoskeleton Marker (ab181595)

References

Ali, R., & Wendt, M. K. (2017). The paradoxical functions of EGFR during breast cancer progression. Signal Transduction and Targeted Therapy, 2 (2016), 1–7.

Chu, P., Wu, E., & Weiss, L. M. (2000). Cytokeratin 7 and Cytokeratin 20 expression in epithelial neoplasms: A survey of 435 cases. Modern Pathology, 13(9), 962–972.

Cowper-Sallari, R., Zhang, X., Wright, J.B., Bailey, S.D., M.D., Eeckhoute, J., Moore, J.H., and L, Mathieu (2012). Breast cancer risk-associated SNPs modulate the affinity of chromatin for FOXA1 and alter gene expression. Nat Genet, 44(11): 1191–1198.

Duffy, M. J., Synnott, N. C., & Crown, J. (2018). Mutant p53 in breast cancer: potential as a therapeutic target and biomarker. Breast Cancer Research and Treatment, 170(2), 213–219.

Fackenthal, J. D., & Olopade, O. I. (2007). Breast cancer risk associated with BRCA1 and BRCA2 in diverse populations. Nature Reviews Cancer, 7(12), 937–948.

Fenner, M.H., & Elstner, E. (2005) Peroxisome proliferator-activated receptor-γ ligands for the treatment of breast cancer, Expert Opinion on Investigational Drugs, 14:6, 557-568

Harris, R. E., Casto, B. C., & Harris, Z. M. (2014). Cyclooxygenase-2 and the inflammogenesis of breast cancer. World Journal of Clinical Oncology, 5(4), 677–692.

Hicks, D., Dell’Orto, P., Falzon, M., Hoff, K. D., Levy, Y. Y., McMahon, L., … Viale, G. (2017). Immunohistochemical performance of estrogen and progesterone receptor antibodies on the dako omnis staining platform: Evaluation in multicenter studies. Applied Immunohistochemistry and Molecular Morphology, 25(5), 313–319.

Jeselsohn, R., Buchwalter, G., De Angelis, C., Brown, M., & Schiff, R. (2015). ESR1 mutations-a mechanism for acquired endocrine resistance in breast cancer. Nature Reviews Clinical Oncology, 12(10), 573–583.

Laakso, M., Loman, N., Borg, Å., & Isola, J. (2005). Cytokeratin 5/14-positive breast cancer: True basal phenotype confined to BRCA1 tumors. Modern Pathology, 18(10), 1321–1328.

Li, J. P., Zhang, X. M., Zhang, Z., Zheng, L. H., Jindal, S., & Liu, Y. J. (2019). Association of p53 expression with poor prognosis in patients with triple-negative breast invasive ductal carcinoma. Medicine, 98(18), e15449.

Lim, E., Palmieri, C., & Tilley, W. D. (2016). Renewed interest in the progesterone receptor in breast cancer. British Journal of Cancer, 115(8), 909–911.

Masuda, H., Zhang, D., Bartholomeusz, C., Doihara, H., Hortobagyi, G. N., & Ueno, N. T. (2012). Role of epidermal growth factor receptor in breast cancer. Breast Cancer Research and Treatment, 136(2), 331–345.

Meyer, K. B., & Carroll, J. S. (2012). FOXA1 and breast cancer risk. Nature Genetics, 44(11), 1176–1177.

Mitri, Z., Constantine, T., & O’Regan, R. (2012). The HER2 Receptor in Breast Cancer: Pathophysiology, Clinical Use, and New Advances in Therapy. Chemotherapy Research and Practice, 2012, 1–7.

Mohammadizadeh. F., Hani M., Ranaee M., and Bagheri M. (2013). Role of cyclin D1 in breast carcinoma. J Res Med Sci. 18(12) 1021–1025

Mohammed, H., Russell, I. A., Stark, R., Rueda, O. M., Hickey, T. E., Tarulli, G. A., … Carroll, J. S. (2015). Progesterone receptor modulates ERα action in breast cancer. Nature, 523(7560), 313–317.

Niazi, M. K. K., Senaras, C., Pennell, M., Arole, V., Tozbikian, G., & Gurcan, M. N. (2018). Relationship between the Ki67 index and its area based approximation in breast cancer. BMC Cancer, 18(1), 1–9.

Ortiz, A. B., Garcia, D., Vicente, Y., Palka, M., Bellas, C., & Martin, P. (2017). Prognostic significance of cyclin D1 protein expression and gene amplification in invasive breast carcinoma. PLoS ONE, 12(11), 1–13.

Piccart-Gebhart M.J… and Richard D. Gelber, Ph.D., for the Herceptin Adjuvant (HERA) Trial Study Team (2005). Trastuzumab after Adjuvant Chemotherapy in HER2-Positive Breast Cancer. New England Journal of Medicine, 353;16.

Qian, X. L., Pan, Y. H., Huang, Q. Y., Shi, Y. B., Huang, Q. Y., Hu, Z. Z., & Xiong, L. X. (2019). Caveolin-1: A multifaceted driver of breast cancer progression and its application in clinical treatment. OncoTargets and Therapy, 12, 1539–1552.

Shaoxian, T., Baohua, Y., Xiaoli, X., Yufan, C., Xiaoyu, T., Hongfen, L., … Wentao, Y. (2017). Characterisation of GATA3 expression in invasive breast cancer: Differences in histological subtypes and immunohistochemically defined molecular subtypes. Journal of Clinical Pathology, 70(11), 926–934.

Singhai, R., Patil, V. W., Jaiswal, S. R., Patil, S. D., Tayade, M. B., & Patil, A. V. (2011). E-Cadherin as a diagnostic biomarker in breast cancer. North American Journal of Medical Sciences, 3(5), 227–233.

Wang, X., Sun, Y., Wong, J., & Conklin, D. S. (2013). PPARγ maintains ERBB2-positive breast cancer stem cells. Oncogene, 32(49), 5512–5521.

Zaha, D. C. (2014). Significance of immunohistochemistry in breast cancer. World Journal of Clinical Oncology, 5(3), 382–392.

Zhang, D., Zhang, J. Y., & Wang, E. H. (2015). δ-Catenin promotes the malignant phenotype in breast cancer. Tumor Biology, 36(2), 569–575.

Zou, J., Wang, C., Ma, X., Wang, E., & Peng, G. (2017). APOBEC3B, a molecular driver of mutagenesis in human cancers. Cell and Bioscience, 7(1), 1–7.