Induction of G1 and G2/M cell cycle arrests by the dietary compound 3,3'-diindolylmethane in HT-29 human colon cancer cells

Department of Food Science and Nutrition, Hallym University, Chuncheon, Republic of Korea.
BMC Gastroenterology (Impact Factor: 2.37). 02/2009; 9(1):39. DOI: 10.1186/1471-230X-9-39
Source: PubMed


3,3'-Diindolylmethane (DIM), an indole derivative produced in the stomach after the consumption of broccoli and other cruciferous vegetables, has been demonstrated to exert anti-cancer effects in both in vivo and in vitro models. We have previously determined that DIM (0 - 30 micromol/L) inhibited the growth of HT-29 human colon cancer cells in a concentration-dependent fashion. In this study, we evaluated the effects of DIM on cell cycle progression in HT-29 cells.
HT-29 cells were cultured with various concentrations of DIM (0 - 30 micromol/L) and the DNA was stained with propidium iodide, followed by flow cytometric analysis. [3H]Thymidine incorporation assays, Western blot analyses, immunoprecipitation and in vitro kinase assays for cyclin-dependent kinase (CDK) and cell division cycle (CDC)2 were conducted.
The percentages of cells in the G1 and G2/M phases were dose-dependently increased and the percentages of cells in S phase were reduced within 12 h in DIM-treated cells. DIM also reduced DNA synthesis in a dose-dependent fashion. DIM markedly reduced CDK2 activity and the levels of phosphorylated retinoblastoma proteins (Rb) and E2F-1, and also increased the levels of hypophosphorylated Rb. DIM reduced the protein levels of cyclin A, D1, and CDK4. DIM also increased the protein levels of CDK inhibitors, p21CIP1/WAF1 and p27KIPI. In addition, DIM reduced the activity of CDC2 and the levels of CDC25C phosphatase and cyclin B1.
Here, we have demonstrated that DIM induces G1 and G2/M phase cell cycle arrest in HT-29 cells, and this effect may be mediated by reduced CDK activity.

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    • "The anticancer activity of DIM has been investigated in various cell lines including prostate, breast, and colon (Abdelbaqi et al., 2011; Chen et al., 2012; Lerner et al., 2012). Further, DIM has been shown to induce cell cycle arrest and apoptosis in HCT-116, SW480, and HT-29 colon cancer cells (Choi et al., 2009; Lerner et al., 2012). 1,1-Bis(3 0 -indolyl)-1-(p-substitutedphenyl)methanes (C-DIMs) are synthetic analogs of DIM that exhibit structure-dependent activation of peroxisome proliferator-activated receptor gamma (PPAR-c) receptor (p-trifluoro, p-tert-butyl, p-cyano, and p-phenyl analogs), and the orphan receptor Nur77/TR3 (unsubstituted and p-methoxy analogs) (Cho et al., 2010, 2008, 2007; Guo et al., 2010; Ichite et al., 2009; Lee et al., 2009; Lei et al., 2008a, 2008b; Safe et al., 2008; Yoon et al., 2011). "
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    ABSTRACT: 1,1-Bis(3-indolyl)-1-(p-substitutedphenyl)methane (C-DIM) compounds exhibit remarkable antitumor activity with low toxicity in various cancer cells including lung tumors. Two C-DIM analogs, DIM-C-pPhOCH3 (C-DIM-5) and DIM-C-pPhOH (C-DIM-8) while acting differentially on the orphan nuclear receptor, TR3/Nur77 inhibited cell cycle progression from G0/G1 to S-phase and induced apoptosis in A549 cells. Combinations of docetaxel (doc) with C-DIM-5 or C-DIM-8 showed synergistic anticancer activity in vitro and these results were consistent with their enhanced antitumor activities in vivo. Respirable aqueous formulations of C-DIM-5 (mass median aerodynamic diameter of 1.92 ± 0.22 um and geometric standard deviation of 2.31 ± 0.12) and C-DIM-8 (mass median aerodynamic diameter of 1.84 ± 0.31 um and geometric standard deviation of 2.11 ± 0.15) were successfully delivered by inhalation to athymic nude mice bearing A549 cells as metastatic tumors. This resulted in significant (p<0.05) lung tumor regression and an overall reduction in tumor burden. Analysis of lung tumors from mice treated with inhalational formulations of C-DIM-5 and C-DIM-8 showed decreased mRNA and protein expression of mediators of tumor initiation, metastasis, and angiogenesis including MMP2, MMP9, c-Myc, β-catenin, c-Met, c-Myc, and EGFR. Microvessel density assessment of lung tissue sections showed significant reduction (p<0.05) in angiogenesis and metastasis as evidenced by decreased distribution of immunohistochemical staining of VEGF, and CD31. Our studies demonstrate both C-DIM-5 and C-DIM-8 have similar anticancer profiles in treating metastatic lung cancer and possibly work as TR3 inactivators.
    Full-text · Article · Jul 2013 · European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences
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    • "Many studies suggest the utility of natural compounds as chemopreventive agents against CRC [14,15]. Some compounds derived from natural sources have been shown to inhibit the cell cycle at points regulated by various components of the Cdk4 pathway, blocking proliferation of cancer cells [16-18]. For example, milk thistle, also referred to as St. Mary's thistle, lady thistle, or holy thistle, contains polyphenolic flavanoid antioxidant compounds composed mainly of silibinin. "
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    ABSTRACT: Background Colorectal cancer (CRC) is the second leading cause of death from cancer in the United States. Colorectal cancers have a prolonged latency following initiation that may span decades providing ample time for implementing a chemoprevention strategy that could block or reverse the progression to CRC. Cdk4 pathway alterations have been linked to a number of cancers including CRC. In these experiments we focused on the Cdk4 pathway and its role in intestinal tumorigenesis as a possible target in chemoprevention strategies. Methods We evaluated the effect of Cdk4 blockade on the prevention of intestinal tumor formation by crossing Cdk4−/− mice to Apc−/+ mice. In addition, we tested the effect of the dietary compound silibinin on the Cdk4 pathway in Apc−/+ mice and HT-29 colon cancer cells in culture. Results Cdk4−/− mice backcrossed to Apc−/+ mice reduced intestinal adenoma formation compared to Apc−/+ controls. Silibinin effectively targeted the Cdk4 pathway causing hypophosphorylation of the retinoblastoma protein, inhibited cell growth, and induced apoptosis. As a result silibinin blocked the development of intestinal adenomas by 52% in this genetic model (Apc−/+ mice) of early events in colorectal cancer formation. No toxic abnormalities were detected in mice which received silibinin. Conclusions Modification of the Cdk4 pathway using a natural plant-derived compound such as silibinin may be a useful chemopreventive strategy for colorectal carcinomas.
    Full-text · Article · Mar 2013 · BMC Cancer
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    • "We found that the inhibitory effect of DIM on the growth of CNE-2 cells may result from G0/G1 cell cycle arrest. In recent research, Choi et al found that DIM inhibited HT-29 human colon cancer cells and was able to induce cell cycle arrest with 10–30 μM DIM, which is consistent with our results (22). This result was strengthened by our examination of proteins controlling the cell cycle phase transition. "
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    ABSTRACT: The antitumor effects of 3,3'-diindolylmethane (DIM) are exhibited in a number of human cancer cells. However, there have been few studies performed concerning the effect of DIM on nasopharyngeal cancer (NPC) cells. In the present study, we examined the in vitro antitumor activity of DIM on the poorly differentiated NPC cell line CNE-2. The potential molecular mechanisms of the activity were also explored. CNE-2 cells were treated with varying concentrations of DIM for different times. Cell proliferation and apoptosis were detected and the molecular mechanisms involved in these effects were characterized. The results demonstrated that DIM at concentrations of 15-100 μM caused dose- and time-dependent inhibition of CNE-2 cell proliferation. Flow cytometry analysis revealed a high sub-G1 cell peak following treatment with DIM, and the rate of apoptosis increased. DIM may elevate the levels of cleaved Bid and Bax and enhance mitochondrial membrane depolarization, allowing the efflux of cytochrome c, Smac and Omi into the cytosol. The levels of caspases-3, -8 and -9 and cleaved poly (ADP-ribose) polymerase (PARP) were upregulated following DIM treatment in a dose-dependent manner. DIM also inhibits the phosphorylation of IκB-α, and showed dose-dependent inhibition of Bcl-2, XIAP and NF-κB in CNE-2 cells in vitro. These results indicate that DIM inhibits cell proliferation by inducing cell cycle arrest at G0/G1 phase and induces the apoptosis of CNE-2 cells by regulating multiple molecules in a mitochondria-dependent pathway. DIM may be a preventive and therapeutic agent against NPC.
    Full-text · Article · Feb 2013 · Oncology letters
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