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. 2012 Nov 30:12:564.
doi: 10.1186/1471-2407-12-564.

Curcumin and synthetic analogs induce reactive oxygen species and decreases specificity protein (Sp) transcription factors by _targeting microRNAs

Shruti U Gandhy  1 , Kyounghyun Kim, Lesley Larsen, Rhonda J Rosengren, Stephen Safe
Affiliations

Curcumin and synthetic analogs induce reactive oxygen species and decreases specificity protein (Sp) transcription factors by _targeting microRNAs

Shruti U Gandhy et al. BMC Cancer. .

Abstract

Background: Curcumin inhibits growth of several cancer cell lines, and studies in this laboratory in bladder and pancreatic cancer cells show that curcumin downregulates specificity protein (Sp) transcription factors Sp1, Sp3 and Sp4 and pro-oncogenic Sp-regulated genes. In this study, we investigated the anticancer activity of curcumin and several synthetic cyclohexanone and piperidine analogs in colon cancer cells.

Methods: The effects of curcumin and synthetic analogs on colon cancer cell proliferation and apoptosis were determined using standardized assays. The changes in Sp proteins and Sp-regulated gene products were analysed by western blots, and real time PCR was used to determine microRNA-27a (miR-27a), miR-20a, miR-17-5p and ZBTB10 and ZBTB4 mRNA expression.

Results: The IC50 (half-maximal) values for growth inhibition (24 hr) of colon cancer cells by curcumin and synthetic cyclohexanone and piperidine analogs of curcumin varied from 10 μM for curcumin to 0.7 μM for the most active synthetic piperidine analog RL197, which was used along with curcumin as model agents in this study. Curcumin and RL197 inhibited RKO and SW480 colon cancer cell growth and induced apoptosis, and this was accompanied by downregulation of specificity protein (Sp) transcription factors Sp1, Sp3 and Sp4 and Sp-regulated genes including the epidermal growth factor receptor (EGFR), hepatocyte growth factor receptor (c-MET), survivin, bcl-2, cyclin D1 and NFκB (p65 and p50). Curcumin and RL197 also induced reactive oxygen species (ROS), and cotreatment with the antioxidant glutathione significantly attenuated curcumin- and RL197-induced growth inhibition and downregulation of Sp1, Sp3, Sp4 and Sp-regulated genes. The mechanism of curcumin-/RL197-induced repression of Sp transcription factors was ROS-dependent and due to induction of the Sp repressors ZBTB10 and ZBTB4 and downregulation of microRNAs (miR)-27a, miR-20a and miR-17-5p that regulate these repressors.

Conclusions: These results identify a new and highly potent curcumin derivative and demonstrate that in cells where curcumin and RL197 induce ROS, an important underlying mechanism of action involves perturbation of miR-ZBTB10/ZBTB4, resulting in the induction of these repressors which downregulate Sp transcription factors and Sp-regulated genes.

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Figures

Figure 1
Figure 1
Structures of cyclohexanone (A) and piperidone (B) analogs and curcumin (C) and their growth inhibitory IC50 values. Growth inhibition was determined as outlined in the Materials and Methods.
Figure 2
Figure 2
Curcumin and RL197 decrease RKO and SW480 cell growth and downregulate Sp1, Sp3 and Sp4 proteins. RKO (A) and SW480 (B) cells were treated with DMSO or different concentrations of curcumin and RL197, and after 24 hr, cell growth was determined as outlined in the Materials and Methods. Results are means ± S.E. for at least 3 replicate determinations and significant (p < 0.05) inhibition compared to DMSO (set at 100%) is indicated (*). Downregulation of Sp1, Sp3 and Sp4 proteins by different concentrations of curcumin (C) and RL197 (D) (after 24 hr) in RKO and SW480 cells was determined by western blot analysis of whole cell lysates as described in the Materials and Methods.
Figure 3
Figure 3
Curcumin and RL197 decrease expression of Sp-regulated gene products. Downregulation of Sp-regulated gene products by different concentration of curcumin in RKO (A) and SW480 (B) cells, and by different concentrations of RL197 in RKO (C) and SW480 (D) cells was determined by western blot analysis as described in the Materials and Methods. Experiments with Sp proteins (Figure 2) and Sp-regulated gene products were part of the same study and have the same β-actin loading controls.
Figure 4
Figure 4
Curcumin and RL197-mediated activation of proteasomes and ROS. RKO (A) and SW480 (B) cells were treated with DMSO (control), curcumin, or RL197 alone or in combination with 1 μM lactacystin for 24 hr ,and effects on cell proliferation or expression of Sp1, Sp3 or Sp4 proteins (western blots) were determined as outlined in the Materials and Methods. RKO (C) and SW480 (D) cells were treated with DMSO, curcumin, RL197 alone or in combination with 5 mM GSH for 24 hr, and whole cell lysates were analyzed by western blot analysis as described in the Materials and Methods. Cell proliferation results (A, B) are means ± S.E. for at least 3 replicate experiments, and significant (p < 0.05) growth inhibition is indicated (*).
Figure 5
Figure 5
The antioxidant GSH attenuates curcumin and RL197-induced responses. RKO cells were treated with curcumin and RL197 for 24 (A) or 18 (B) hr, and induction of ROS was investigated by FACS analysis as outlined in the Materials and Methods. RKO cells were treated with DMSO, curcumin, and RL197 alone and in combination with GSH for 12 (C) or 24 (D) hr, and effects on MMP or cell proliferation, respectively, were determined as outlined in the Materials and Methods. Results are means ± S.E. for at least 3 replicate determinations, and significant (p < 0.05) induction of ROS, MMP or cell proliferation (*) and inhibition after cotreatment with GSH (**) is indicated.
Figure 6
Figure 6
Curcumin and RL197 disrupt miR-ZBTB10/ZBTB4 interactions. RKO cells were treated with DMSO, curcumin, and RL197 alone or in combination with GSH, and induction of ZBTB10 or ZBTB4 (A) and downregulation of multiple miRs (B) were determined by real time PCR as outlined in the Materials and Methods. Results are means ± S.E. for at least 3 replicate determinations and significant (p < 0.05) induction of ZBTB10 or ZBTB4 and suppression of miRs (*) and inhibition of these responses by GSH (**) are indicated. (C) Curcumin and RL197-dependent downregulation of Sp1, Sp3 and Sp4 mRNA levels was determined in RKO cells as outlined in the Materials and Methods. Results are means ± S.E. (3 replicates) and significant (p < 0.05) inhibition is indicated. (D) Proposed mechanism of action of curcumin and RL197 in RKO cells.
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References

    1. Koehn FE, Carter GT. The evolving role of natural products in drug discovery. Nat Rev Drug Discov. 2005;4:206–220. - PubMed
    1. Butler MS. The role of natural product chemistry in drug discovery. J Nat Prod. 2004;67:2141–2153. - PubMed
    1. Aggarwal BB, Shishodia S. Molecular _targets of dietary agents for prevention and therapy of cancer. Biochem Pharmacol. 2006;71:1397–1421. - PubMed
    1. Gupta SC, Kim JH, Prasad S, Aggarwal BB. Regulation of survival, proliferation, invasion, angiogenesis, and metastasis of tumor cells through modulation of inflammatory pathways by nutraceuticals. Cancer Metastasis Rev. 2010;29:405–434. - PMC - PubMed
    1. Sharma RA, McLelland HR, Hill KA, Ireson CR, Euden SA, Manson MM, Pirmohamed M, Marnett LJ, Gescher AJ, Steward WP. Pharmacodynamic and pharmacokinetic study of oral Curcuma extract in patients with colorectal cancer. Clin Cancer Res. 2001;7:1894–1900. - PubMed

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