Differentiation of protein expression in mammary normal cells and mammary cancer cells and how to identify differences between normal and cancer cell lines with Immunohistochemistry.
Hello Juthathip Jurutha
As cancer cells display unique characteristics in comparison to normal cells, you may take advantage of these differences to differentiate between normal and cancer cells.
For instance, Breast cancer cells may overexpress specific receptors which, when activated can initiate downstream signaling resulting in the expression of genes for cancer cell proliferation, growth, survival, migration, angiogenesis and other vital cell cycle pathways.
There are various types of breast cancer, some have hormone receptors like estrogen or progesterone (some have both) and are called ER+ or PR+ breast cancer respectively. Other most common receptors that are overexpressed in breast cancer cells are part of the epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases, for example, EGFR and HER2 are overexpressed in approximately 40% and 25% of breast cancers respectively and are believed to be responsible for more aggressive tumor behavior and poor prognosis.
You may use antibodies against these receptors and check for the expression of the protein in both normal and cancer cells. You may use immunohistochemistry for confirming the expression and expression location of proteins in tissue sections. For cell lines, you may use immunocytochemistry (ICC) which is performed on sample of intact cells. ICC is a common laboratory assay that can confirm the expression and location of target peptides or protein antigens in the cell via specific combination of antibodies and target molecules. These bound antibodies can then be detected using several different methods. It will allow you to evaluate whether or not cells in a particular sample express the antigen in question. In cases where an immunopositive signal is found, ICC will allow you to determine which sub-cellular compartments are expressing the antigen.
There are two different immunocytochemistry assays:
1. Indirect ICC which mainly includes preparation and culture of cells, cell fixation, serum blocking, primary antibody incubation, labelled secondary antibody incubation, staining, result judgment and imaging.
2. Direct ICC in which only labelled primary antibody is used without the secondary antibody, and the other steps are the same as that followed in indirect immunocytochemistry.
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