Question

Describe how excess HER2/ERBB2 expression can cause breast cancer. Describe how the abs.ence of HER2/ERBB2 expression can cause breast cancer

Answer 1

Cancer is caused by diverse factor and it’s quite unknown the exact reason why a tumor arose. There are environmental factors, gene that predispose to cancer and lifestyle involved. Depending which type of cancer we are considering the risk factor to consider.

Particularly breast cancer primary risk factors are being female and older age. Other potential risk factors include genetics, lack of childbearing or lack of breastfeeding, higher levels of certain hormones, certain dietary patterns, and obesity.

HER2 (human epidermal growth factor receptor 2) is a member of the human epidermal growth factor receptor (HER/EGFR/ERBB) family. Normally, this protein helps breast cells grow, divide, and repair themselves. Amplification or over-expression of this oncogene has been shown to play an important role in the development and progression of certain aggressive types of breast cancer. As HER2 is amplified, we will have more HER2 on membrane so more signaling will be occurring and promoting cell proliferation and opposes apoptosis, and therefore must be tightly regulated to prevent uncontrolled cell growth from occurring. In recent years the protein has become an important biomarker and target of therapy for approximately 30% of breast cancer patients by a monoclonal antibody: trastuzumab.

Also, there is breast cancer HER2 negative. This means they lack of expression of these receptors so, carcinogenesis is due to other molecular mutations that leads to uncontrolled cell division. Some of these mutations involver BRCA1 and BRCA2 (proteins involved in DNA reparation), p53 (regulator of cell cycle) or PTEN (regulator of PI3K/Akt signaling pathway that produce uncontrolled cell growth).