Where are HER2 proteins found?

Where are HER2 proteins found?

The HER2 receptor is a 1255 amino acid, 185 kD transmembrane glycoprotein located at the long arm of human chromosome 17 (17q12) [6]. HER2 is expressed in many tissues and its major role in these tissues is to facilitate excessive/uncontrolled cell growth and tumorigenesis [7–9].

What causes HER2 overexpression in breast cancer?

Extra copies of the ERBB2 (HER2) gene (gene amplification) have been found in a number of different cancers. This causes the cancer cells to make excess HER2 (overexpression), which in turn, tells the cells to grow and divide in an uncontrolled manner.

Why is HER2 an oncogene?

HER2 is a membrane tyrosine kinase and oncogene that is overexpressed and gene amplified in about 20% of breast cancers. When activated it provides the cell with potent proliferative and anti-apoptosis signals and it is the major driver of tumor development and progression for this subset of breast cancer.

How is HER2 activated?

HER2 can also be activated by complexing with other membrane receptors such as insulin-like growth factor receptor 1 [12]. Figure 1 [13] shows the main transduction pathways regulated by the four HER family members—EGFR, HER2, HER3, and HER4.

Is HER2 A protein?

HER2 is a growth-promoting protein on the outside of all breast cells. Breast cancer cells with higher than normal levels of HER2 are called HER2-positive. These cancers tend to grow and spread faster than other breast cancers, but are much more likely to respond to treatment with drugs that target the HER2 protein.

How is the HER2 gene linked to cancer?

In 1987, he and his colleagues discovered that the growth factor receptor gene HER2, which produces HER2 proteins, might be a good candidate. At the same time, a team of NCI researchers led by Stuart Aaronson, M.D., were among the first to show that the HER2 protein could cause normal cells to grow uncontrollably like aggressive cancer cells.

What happens when there is too much HER2 in a cell?

When a mutation results in too many copies within a cell ( amplification ), HER2 then produces too much of the HER2 protein, causing HER2 to act as an oncogene, meaning that it can promote uncontrolled, cancerous growth. This happens in about one in five breast cancers and can also occur in other cancers, such as stomach and esophagus cancers.

Is the HER2 mutation associated with HER2 amplification?

HER2-positive lung cancer may not be an adequate term, and patient cohorts for the study of HER2-targeted agents should be defined by the specific HER2 alteration present. HER2 mutations are not associated with HER2 amplification, thus suggesting a distinct entity and therapeutic target.

Can a HER2 overexpression cause breast cancer?

Most of the studies on HER2 have been carried out in breast cancer, after it was found to induce mammary carcinogenesis in vitro [ 14] and in vivo [ 15 ]. Amplification or overexpression of the HER2 gene occurs in approximately 15–30% of breast cancers [ 16 ].