[Effects of retinoid Ro 40-8757 on human cancer cell lines in vitro]

The retinoids are potent anti-tumor drugs affecting cellular proliferation and inducing cell differetiation or apoptosis. This study was designed to investigate the anti-proliferative effect of a new-developed retinoid, Ro 40-8757, on cell structure, cell cycle and cell cycle proteins of four human cancer cell lines in vitro in order to reveal its probable mechanism.

MTT assay was used to determine the anti-proliferative effects of Ro 40-8757 on human cancer cell lines CCL-187, CCL-229, JF-305, and ASPC-1. Microscopy was used to observe CCL-187 morphological changes. Flow cytometry was performed to investigate the influence of Ro 40-8757 on cell cycle. Western blot analysis was conducted to detect the cell cycle proteins p16, p21, and p27 as to discuss the possible mechanism.

Ro 40-8757 significantly inhibited the growth of the four cancer cell lines in a dose-, time-dependent manner and without any signs of cytotoxicity, differentiation, or apoptosis. After treating with Ro 40-8757, the cell of CCL-187 was arrested at G0/G1 phase. Both p21 and p27 were rapidly increasing at the first 12 hours after exposed to the agent, then decreasing slowly in the 24, 48 hours, and increasing again in 72 to 144 hours. P16 did not express at all either before or after agent treatment.

The results suggest that Ro 40-8757 inhibits the growth of human cancer cell lines in vitro by means of cell cycle arrest (mediated by up-regulating cell cycle protein P21 and P27) instead of cytotoxic effects, differentiation, or apoptosis.