Retinoic Acid Induces Apoptosis of Prostate Cancer DU145 Cells through Cdk5 Overactivation

Figure 6

RA-triggered caspase 3 activation can be blocked by Cdk5 knockdown. DU145 cells were treated as follows: control, RA (10 μM), RA + sicdk5, sicdk5 (5 pmol/10⁴ cells) for 4 days after 1-day serum-free pretreatment. The control group was transfected with siRNA-control. (a, f) Cleaved caspase 3, p25, Cdk5, and cleaved PARP proteins were detected by immunoblotting with specific antibodies as described in Materials and Methods. β-actin serves as an internal control. Cdk5 activity was detected by in vitro kinase assay using histone H1 as a substrate. ((b)–(e), (g)) The quantitative data, respectively, revealed the results of cleaved caspase 3, p25 formation, Cdk5, cleaved PARP protein levels, and Cdk5 activation. The independent experiments were repeated 3 times. Data are represented as means ± SEM; * and ^∗∗𝑃<0.05 and 𝑃<0.01 versus control group; ⁺⁺𝑃<0.01 versus RA = 10 group.

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