Transgenic introduction of androgen receptor into estrogen-receptor-, progesterone-receptor-, and androgen-receptor-negative breast cancer cells renders them responsive to hormonal manipulation.

Background: Estrogen-receptor (ER)-, progesterone-receptor (PR)-, and androgen-receptor (AR)-negative breast cancer cells are unaffected by treatment with dehydroepiandrosterone-sulfate (DHEAS) and an aromatase inhibitor (AI). We hypothesized that cell growth would be inhibited with DHEAS/AI treatment after successful transfection of an AR expression vector.

Methods: ER/PR/AR-negative breast cancer cells were transfected with an AR expression vector and treated with DHEAS/AI for 2 days. Growth inhibition of these cells was compared with that of transfected cells treated with only AI or with nontransfected cells treated with DHEAS/AI. Mann-Whitney U test was used to determine statistical significance.

Results: Cell death rates of 53.5% (P = .001) and 40.1% (P = .006) were seen in transfected cells treated with DHEAS/AI compared with controls for days 1 and 2, respectively. Nontransfected cells were unaffected by treatment.

Comments: ER/PR/AR-negative cells transfected with AR were killed by DHEAS/AI treatment, providing evidence that AR is responsible for this effect. This provides the first AR-targeted hormonal therapy for ER breast cancer.