Curcumin Suppresses microRNA-7641-Mediated Regulation of p16 Expression in Bladder Cancer

Bladder cancer has a high recurrence rate and requires adjuvant intravesical management after surgery. The use of traditional agents for bladder cancer therapy is constrained by their toxicity and limited efficacy. This emphasizes the need for the development of safer, more effective compounds such as instillation agents. Curcumin is the major component of turmeric, the powdered root of Curcuma longa, which is known for its anti-inflammatory, anti-oxidant and anticancer properties. First, a microarray profiling and qPCR analysis were conducted in the T24 and SV-HUC-1 cell lines. Then, we examined the potential tumorigenicity of miR-7641 in the T24 and SV-HUC-1 cell lines with or without curcumin. Western blot analysis showed that p16 is a target of miR-7641 in T24 cells. We found that, for the first time, curcumin directly downregulates a tumor-promoting microRNA (miRNA), miR-7641, in bladder cancer, which has tumor-promoting characteristics. Curcumin induces the downregulation of miR-7641 and subsequent upregulation of p16 which is a target of miR-7641 at the post-transcriptional level, which leads to the decreased invasion and increased apoptosis of bladder cancer cells. This is the first report to show a direct effect of curcumin on inducing changes in a miRNA suppressor with direct anticancer consequences in bladder cancer. Our study shows that curcumin may be a candidate agent for the clinical management of non-muscle-invasive bladder cancer.