The effect of tamoxifen on established human colorectal cancer cell lines in vitro.

UNLABELLED

The purpose of this study was to evaluate the effect of the anti-estrogenic tamoxifen (Tx) on the growth of human colorectal cancer cells.

METHODS

Serial concentrations (0.005 microM, 0.05 microM, 0.5 microM, 5 microM, and 50 microM) of the anti-estrogenic tamoxifen (Tx) were added and analyzed for their effect on the growth of established human colorectal cancer cells. HT-29 and SW-620 colon cancer cells and SW-1463 rectal cancer cells were tested in both serum-free media and serum-containing media (10% fetal calf serum). COLO-205 colon cancer and SW-837 rectal cancer cells were only tested in 10% fetal calf serum-containing media. Cell growth was measured with the hexosaminidase assay and was compared among the different groups. Cells were analyzed for estrogen receptors using enzyme immunoassay.

RESULTS

In serum-free media, Tx inhibited the growth of HT-29 (P = .05) and SW-620 (P = .01) colon cancer cells at all concentrations tested.

RESULTS

In serum-containing media, Tx inhibited (P = .04) the growth of the SW-837 rectal cancer cells at all concentrations and SW-1463 (P = .05) rectal cancer cells at the concentrations of 0.05 microM and 0.5 microM Tx. The inhibition of cell growth in HT-29, SW-620 and SW-1463 line was greater (P < .001) under serum-free media conditions. Estrogen receptors were not detected in any of the cell lines tested.

CONCLUSIONS

Hormonal manipulation with colo-rectal cancers is possible, but the effect of Tx on the growth of colon cancer cells differs from the effect on rectal cancer cells under various conditions. The mechanism of inhibition is not clear yet, and further studies are warranted before any clinical implications can be postulated.