Expression of the oestrogen responsive protein pS2 in human breast cancer

The trefoil peptide pS2 was discovered in a breast cancer cell line as a re sult of its oestrogen responsive character. The expression of pS2 in breast tumours in vivo is also likely to be an oestrogenic effect and as such, th e presence of pS2 in oestrogen receptor positive breast cancer is evidence of an intact oestrogen response pathway and an indicator of putative hormon e responsiveness. Consistent with this, clinical studies of breast cancer h ave revealed a correlation between pS2 expression and favourable tumour cha racteristics as well as response to endocrine therapy.