Triple Negative Breast Cancer – Differentiation of TNBC (ER-, PR-, and HER2/neu-) using New miRNA Biomarker Panel

**Ready-to-Use fully optimized SSNA miRNA In Situ Hybridization (ISH) Kit**

Like many cancers, breast cancers are highly diverse with a range of distinct clinical outcomes. Breast cancers dependent on hormone signaling (estrogen receptor [ER]/ progesterone receptor [PR]) or on epidermal growth factor receptor (HER2/neu) typically have the most positive prognosis. Tumors’ lacking these receptors expression, referred to as triple-negative breast cancer (TNBC), is a poorly differentiated, highly malignant, aggressive type of breast cancer associated with poor prognosis. TNBC represents approximately 10-20% of all cases of breast cancer and is characterized by shorter overall survival. TNBC has a higher mortality and risks of metastasis compared with other subtypes of breast cancer and currently have no specific targeted therapies available for treatment. The five-year survival rate for TNBC is around 77% versus 93% for other breast cancer types, and therefore correct diagnosis of TNBC cases at an early stage is critical for treatment effectiveness. Numerous studies have demonstrated that aberrantly expressed microRNAs (miRNAs) are involved in the pathogenesis of the aggressive TNBC phenotype. miRNAs are small, noncoding RNA molecules that are involved in many critical cellular processes including oncogenesis. Different cancer types and subtypes at different stages of progression display unique miRNA profiles that may be used as diagnostic, prognostic and therapeutic tools. The detection of miRNA in clinical samples has been difficult, requiring total RNA extracts which lack critical spatial information. However, in situ hybridization (ISH) assays have enabled the direct assessment of miRNA expression levels in formalin-fixed paraffin-embedded (FFPE) malignant tissues.

Super Sensitive Nucleic Acid (SSNA) miRNA probes:

BioGenex has developed proprietary Super Sensitive Nucleic Acid (SSNA) miRNA probes that enhance signals from intrinsically low populated miRNAs. The SSNA oligos are synthesized using specially designed bases to give super high melting temperatures. The high melting temperatures enable stringent washes at elevated temperatures to remove non-specific binding. BioGenex miRNA probes are dual-end labeled on 3’ and 5’ with five FAM molecules that amplify the signal, giving intense stains. The high-density fluorophore-labeled SSNA probes combined with the BioGenex Super Sensitive ™ Detection System aid in studying the lowly expressed miRNA populations and miRNA expression profiles to assess the physiological function of miRNA.

The miRNA expression profiles are used to assess the cancer type or conditions for the below types:

Cancer of unknown primary
Undifferentiated and poorly differentiated tumors
Classification of cancer subtypes
Grading and staging of cancer

BioGenex is pleased to launch four Super Sensitive Nucleic Acid miRNA ISH (SSNA miRNA ISH) probes and automated systems for differentiation of TNBC from other breast cancer types. All four miRNAs are not essential for the differentiation of TNBC, and any one SSNA miRNA probe can be used independently to differentiate TNBC from other subtypes. Molecular differentiation using miRNA probes have demonstrated promising results in identifying the expression level of cell-specific miRNAs that can be used as a potential biomarker for differentiation of TNBC cells. Although the detection of miRNA in clinical samples has been difficult, requiring total RNA extracts which lack critical spatial information; BioGenex ISH system has enabled direct assessment of miRNA expression levels in FFPE malignant cells, while preserving the spatial context of the tissue sample thus allowing precise tumor characterization. Evaluation of miRNA profiles using BioGenex Super Sensitive Nucleic Acid (SSNA) probes holds promise for improving understanding of pathogenesis and therapeutic outcome in patients with TNBC. BioGenex offers over 240 miRNA probes together with ISH detection systems, and automation-based platforms, which allow high throughput and accurate detection of miRNAs in tissue samples. BioGenex’s unique miRNA probe technology enables detection of single nucleotide mismatch thus allowing high sensitivity and specificity with a clean intense staining.

The miRNA expression profile was evaluated in 10 normal and 18 FFPE breast cancer tissues. Breast cancers were subtyped using immunostains for ER, PR, and HER-2/neu. Sub-categorization of breast cancer resulted in 5 ER/PR+, 5 Her2+, and 8 TNBC. Differential expressions of the miRNAs were documented using the super sensitive BioGenex Xmatrx® automated system and miRNA ISH TNBC panel probes. BioGenex miRNA ISH panel probes are currently one of the best products for complex diagnostic assays. In the TNBC samples, miR-21, miR-221, and miR-222 were strongly upregulated, while miR-205 was downregulated, suggesting differential miRNA expression pattern between the TNBC cells and other breast tumor tissues. miR-21 was upregulated in 50% (2/4), miR-221 in 50% (4/8) and miR-222 in 63% (5/8) of cases, while miR-205 was downregulated in 37.5% (3/8) of cases. Additional research has indicated that the overexpression of miR-221 and miR-222 is related to clinicopathological factors and prognosis of TNBC (1). While, previous studies have also noted the downregulation of miR-205 in TNBC (2, 3). These miRNA probes may hold promise as potential biomarkers and therapeutic targets for patients with TNBC.

Please click on above links to download Biomarker Panel and Application Note for Differentiation of triple-negative breast cancer.

BioGenex also has an extensive catalog of over 240 unique miRNA probes

References

Li Y et al. miR-221/222 promotes S-phase entry and cellular migration in control of basal-like breast cancer. Molecules. 2014;19:7122-37.
Huo L et al. MicroRNA expression profiling identifies decreased expression of miR-205 in inflammatory breast cancer. Mod Pathol. 2016;29:330-46.
Piovan C et al. Oncosuppressive role of p53-induced miR-205 in triple negative breast cancer. Mol Oncol. 2012;6:458-72.