Kruppel-like factor 2 mediated anti-proliferative and anti-metastasis effects of simvastatin in p53 mutant colon cancer

The changes in cellular metabolism play an important role in promoting tumor progression. Recent findings suggested that the mutation of tumor suppressor gene p53 promoted lipids synthesis and mutant p53 (mutp53) was essential for regulating mevalonate pathway for cholesterol synthesis. Simvastatin, a 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitor, was found to exhibit therapeutic effects against many types of cancers including breast cancer, colon cancer, lung cancer, etc. However, the underlying mechanism of the antitumor effect of simvastatin still needs to be further investigated. Our data demonstrated that suppression of mevalonate pathway by simvastatin significantly upregulated Kruppel-like factor 2 (KLF2) and p21^WAF1/CIP1 expression in mutp53 colon cancer cells SW1116 but not in p53 wild type cells HCT116. Meanwhile, we found that overexpression of KLF2 could significantly induce p21^WAF1/CIP1 expression, inhibit Wnt signaling and suppress epithelial-mesenchymal transition, indicating that KL2 might mediate antitumor effect of simvastatin in SW1116 cells. Moreover, bioinformatic analysis from The Cancer Genome Atlas (TCGA) database indicated that KLF2 were positively correlated with CDKN1A (encoding p21^WAF1/CIP1), both of which were downregulated in colon cancer tissue, especially in p53 mutant colon cancer tissue. The results showed that KLF2 might be a tumor suppressor gene in colon cancer, which was in accordance with our experimental data. We also found that CDKN1A expression in mutant p53 colon cancer tissue was significant decreased when compared with p53 wild type colon cancer tissue, while Wnt ligand Wnt5a exhibited the highest level in p53 mutant colon cancer tissue. These data provide strong evidences for clinical application of simvastatin in treatment of colon cancer with p53 mutation.