3,3’-Diindolylmethane Enhances Paclitaxel Sensitivity by Suppressing DNMT1-Mediated KLF4 Methylation in Breast Cancer

Abstract

Paclitaxel (PTX) is a first-line chemotherapeutic drug for the treatment of breast cancer, but drug resistance seriously limits its clinical use. The aim of the present work was to explore the effect of 3,3’-diindolylmethane (DIM) on PTX sensitivity and its possible mechanism in breast cancer. The expression of Krüppel-like factor 4 (KLF4) and DNA-methyltransferase 1 (DNMT1) in breast cancer tissues were assessed by immunohistochemistry and Western blotting. The methylation of KLF4 was evaluated by the MassARRAY platform. The lentivirus carrying KLF4 and DNMT1 gene or shRNA targeting DNMT1 were used to overexpress KLF4 or knockdown DNMT1 in MCF-7 and T47D breast cancer cells and the role of KLF4 and DNMT1 in regulation of PTX sensitivity was investigated. The effect of PTX on inhibiting the proliferation of MCF-7 and T47D cells was measured by CCK-8 assay. Flow cytometry was used to examine cell apoptosis. The expression of mRNA and protein was evaluated by qRT-PCR and Western blotting analysis, respectively. Our data showed that the expression of DNMT1 was increased, and the methylation level of CpG sites (−148 bp) in the KLF4 promoter was increased while the KLF4 expression was significantly decreased in breast cancer tissues. Overexpression of KLF4 increased the sensitivity of MCF-7 and T47D cells to PTX. DNMT1 increased the methylation of the KLF4 promoter and decrease the expression of KLF4. Knockdown of DNMT1 increased the sensitivity of MCF-7 and T47D cells to PTX. DIM enhanced the PTX sensitivity of MCF-7 and T47D cells, decreased the expression of DNMT1 and the methylation level of KLF4 promoter, thus increasing the level of KLF4. Furthermore, overexpression of DNMT1 attenuated the effect of DIM on the regulation of PTX sensitivity. Collectively, our data indicated that DNMT1-mediated hypermethylation of KLF4 promoter leads to downregulation of KLF4 in breast cancer. The level of KLF4 is correlated with the sensitivity of MCF-7 and T47D cells to PTX. DIM could enhance the antitumor efficacy of PTX on MCF-7 and T47D cells by regulating DNMT1 and KLF4.

SIRT2-KLF4 Interactions are Critical for Myeloma Survival and Migration

“…The Kruppel-like factor 4 (KLF4), first isolated from the NIH3T3 cDNA library in 1994, is also known as GKLF [ 20 , 21 ]. As a universal transcription factor, KLF4 exists in a wide range of organisms, from zebrafish to humans, and remains highly conserved [ 22 ].…”

In Vitro and In Vivo Preventive Effects of Thymoquinone against Breast Cancer: Role of DNMT1

“…DNMT1 was reported to be overexpressed in the MCF-7 and T47D breast cancer cell lines [ 31 , 32 ], and its downregulation led to cell proliferation inhibition and the induction of apoptosis [ 32 ]. In line with this, our results showed that at 30 µM of TQ, mRNA expression levels of the DNMT1 gene were significantly decreased in both MCF7 and T47D cell lines ( Figure 7 A).…”

Krüppel-like factors in tumors: Key regulators and therapeutic avenues

“…KLF4 induces the development of sorafenib resistance within HCC, and the inhibition of KLF4 expression with short hairpin RNA recovered the response of sorafenib-resisted HCC cell lines to sorafenib ( 223 ). The increased methylation level of CpG sites in the KLF4 promoter and decreased expression level of KLF4 in BC tissues lead to the resistance to paclitaxel, which has become the target of 3,3’-diindolylmethane in improving the effectiveness of cancer chemotherapy ( 224 ).…”