Her2-neu by FISH

HER2/neu (Human Epidermal Growth Factor Receptor 2), also known as ERBB2, is a gene that encodes a protein involved in cell growth and division. In breast cancer and some other types of cancer, the HER2/neu gene can be amplified or overexpressed, leading to uncontrolled cell growth and an aggressive cancer phenotype. Testing for HER2/neu status is crucial in breast cancer diagnosis and treatment planning. Fluorescence In Situ Hybridization (FISH) is one of the methods used to determine the HER2/neu status in breast cancer. Here’s how HER2/neu testing by FISH works:

• Sample Collection: A tissue sample (usually from a biopsy or surgical resection of the tumor) is collected from the patient.
• Tissue Preparation: The tissue sample is processed and prepared for FISH analysis. This often involves fixing the tissue and preparing thin slices on glass slides.
• FISH Probe Preparation: In FISH, specific DNA probes are used to target and bind to the HER2/neu gene region. These probes are designed to bind to the HER2/neu gene or the adjacent chromosome region.
• Hybridization: The prepared tissue sample is exposed to the DNA probes. If the HER2/neu gene is amplified (meaning there are more copies of it than usual), the probes will bind to these extra copies.
• Fluorescent Labeling: The DNA probes used in FISH are typically labeled with fluorescent molecules. When these probes bind to the target DNA sequences, they emit fluorescence, allowing for visualization.
• Imaging and Analysis: The tissue sample is examined under a fluorescent microscope. The presence and number of fluorescent signals associated with the HER2/neu gene are assessed. If there is an increased number of HER2/neu gene copies (usually defined as HER2/neu gene amplification), it indicates a positive HER2 status.