Retinoic Acid Receptor γ (RARγ)
CD437 is a selective RARγ agonist. Growth inhibition by CD437 in these lung cancer cell lines is apparent after 2 days of treatment with 10 μM CD437. Dose-response experiments demonstrate that CD437 reduces the numbers of H460, SK-MES-1, A549, and H292 cells with 50% inhibitory values of approximately 0.5, 0.4, 3, and 0.85 μM, respectively. Treatment for 72 h with CD437 causes a strong dose-dependent growth inhibition in all melanoma cell lines. At a concentration of 5 μM CD437, only about 5 to 25% of the cells remain viable after 3 d. The concentrations of CD437 required for 50% growth inhibition (IC50) range from 10 μM for MeWo to 0.1 μM for SK-Mel-23 showing the highest sensitivity.
Tumors in CD437-treated mice stop growing, an effect that becomes already statistically significant (P<0.01) at day 13, 3 d after first administration of CD437, and is maintained for more than 3 wk after discontinuation of treatment. Further histologic analysis demonstrates marked c-fos mRNA levels at the tumor-stroma edge in CD437-treated tumors.