Elevated levels of HSF1 indicate a poor prognosis in breast cancer.

HSF1 is the transcriptional activator of heat shock protein genes in both cell stress and cancer. The studies of Santagata et al. clearly establish that HSF1 levels are increased in the nuclei of mammary cancer cells, both at the in situ and invasive stages, and that these levels are closely correlated with increased mortality. HSF1 levels were elevated in estrogen receptor-positive cells, as well as HER2-expressing and triple-negative breast cancer cells, and higher levels of nuclear HSF1 were associated with a poor prognosis. These studies establish a clear role for HSF1 in human mammary carcinoma and suggest the potential for targeting HSF1 in breast cancer treatment.