A requirement for dimerization of HP1Hsalpha in suppression of breast cancer invasion.

The development and progression of cancer is controlled by gene expression, often regulated through chromatin packaging. Heterochromatin protein 1(Hsalpha) (HP1(Hsalpha)), one of three human HP1 family members, participates in heterochromatin formation and gene regulation. HP1(Hsalpha) possesses an amino-terminal chromodomain, which binds methylated lysine 9 of histone H3 (meK9 H3), and a carboxyl-terminal chromoshadow domain (CSD) that is required for dimerization and interaction with partner proteins.

Conserved properties of HP1(Hsalpha).

Heterochromatin protein 1 Hsalpha (HP1(Hsalpha)) is one of three human proteins that share sequence similarity with Drosophila HP1. HP1 proteins are enriched at centric heterochromatin and play a role in chromatin packaging and gene regulation. In humans, HP1(Hsalpha) is down-regulated in highly invasive/metastatic breast cancer cells, compared to poorly invasive/non-metastatic breast cancer cells.

Regulating the tumor suppressor gene maspin in breast cancer cells: a potential mechanism for the anticancer properties of tamoxifen.

Purpose: Mammary epithelial cells and the majority of breast cancer tumors require estrogen for continued growth. Antiestrogen therapy alone, or in combination with other drugs, has long been a common procedure for breast cancer treatment and prophylaxis. Thus, there is a critical need to elucidate the mechanism(s) of action of antiestrogen treatment, especially for patients who are at risk of breast cancer development or who are currently receiving hormone therapy.