Acetaminophen Alters Estrogenic Responses in Vitro: Stimulation of DNA Synthesis in Estrogen-Responsive Human Breast Cancer Cells

Abstract

A limited number of studies have investigated the estrogenic potential of acetaminophen but none has reported its effects on breast cells. Many compounds that alter estrogen-mediated processes in various tissues contain p-phenolic moieties. Acetaminophen is a commonly used analgesic/antipyretic that also contains a p-phenol. This study tested the hypothesis that therapeutic concentrations of acetaminophen alter estrogen-responsive human breast cancer cell DNA synthesis. To this end, a modified E-screen assay was developed to determine the response to acetaminophen of two dichotomous types of human breast cancer cell lines: estrogen-responsive (MCF7, T47D, ZR-75-1) and estrogen-nonresponsive (MDA-MB-231, HS578T). Cells were placed in estradiol-free medium and then exposed to 3 nM estradiol or 0.03-1 mM acetaminophen. The proliferative response was assessed by determining [3H]thymidine incorporation into DNA and by determining the percentage of cells in the DNA synthesis (S) phase of the cell cycle. Concentrations of acetaminophen commonly attained in human plasma with therapeutic doses of this drug (approximately 0.1 mM) were found as effective as estradiol in stimulating DNA synthesis in estrogen-responsive breast cancer cells. Higher acetaminophen concentrations (1 mM) stimulated estrogen-responsive cells to a lesser extent. The combination of estradiol and acetaminophen did not stimulate DNA synthesis in estrogen-responsive cells more than either agent alone. Neither acetaminophen nor estradiol stimulated DNA synthesis in estrogen-nonresponsive human breast cancer cells. These novel findings demonstrate that therapeutic acetaminophen concentrations specifically stimulate estrogen-responsive breast cancer cell DNA synthesis, suggesting that this drug may exert estrogenic effects.

Biological activities of a novel selective oestrogen receptor modulator derived from raloxifene (Y134)

“…The proliferation assay for T47D cells was conducted in the same manner except that the cell density used was 3000 per well and E 2 concentration was 10 n M . The ER‐negative cell line (MDA‐MB‐231; Harnagea‐Theophilus and Miller, 1998 ) maintained in Leibovitz's L‐15 medium containing 10% BFS was used as control. Cells (1500 per well) were seeded onto 96‐well microtitre plates and incubated with 10 n M E 2 and various concentrations of test compounds for 3 days followed by the above MTT measurement.…”

Effects of acetaminophen on estrogen-responsive alkaline phosphatase in Ishikawa endometrial cancer cells

“…This study tests the hypothesis that APAP will have estrogen-like activity on estrogen-inducible alkaline phosphatase activity in Ishikawa cells. Previous studies demonstrate that APAP has estrogen-like activity in breast cancer cell proliferation studies (Harnagea-Theophilus et al, 1998) and inhibits estrogen-induced vitellogenin production in isolated trout liver cells (Miller et al, 1999). No appreciable interactions between APAP and the estrogen receptor have been found (Harnagea-Theophilus b et al, 1999, Isenhower et al, 1986 and the mechanism by which APAP alters these estrogenic-responses is unclear.…”

“…Previous studies in our laboratory have shown that APAP induced cell proliferation in ER+ MCF-7 breast cancer cells and that antiestrogens inhibit APAP-induced proliferation (Harnagea-Theophilus et al, 1998). It was hypothesized that APAP would have a similar stimulatory effect on estrogen-inducible alkaline phosphatase activity in Ishikawa cells.…”

“…Recent studies have shown that APAP has the ability to alter estrogen responses in vitro in ER+ breast cancer cells. One study examined the effect of therapeutic concentrations of APAP upon estrogen-mediated DNA synthesis in ER+/PR+ and ER-/PR-breast cancer cells (Harnagea-Theophilus et al, 1998). Acetaminophen's estrogenic activity has been investigated in another estrogen-dependent process, the production of vitellogenin in isolated trout liver cells.…”

“…APAP contains a p-hydroxyl group and lipophylic conjugated six-member ring structure like estradiol (Cunningham et al, 1997). In vitro studies have shown that acetaminophen has the ability to induce estrogen-mediated DNA synthesis and cell proliferation in estrogen receptor positive (ER+) breast cancers cells (Harnagea-Theophilus et al, 1998) and inhibits estradiol-induced vitellogenin production in trout liver cells . Although no estrogenic activity was observed in uterotropic bioassays (Harnagea-Theophilus b et al, 1999, Isenhower et al, 1986, animal studies have shown that APAP reduced the number of litters per breeding pair, increased abnormal sperm counts and increased testicular atrophy in mice (Boyd et al, 1970, Reel et al, 1992.…”