Pterostilbene acts through metastasis-associated protein 1 to inhibit tumor growth, progression and metastasis in prostate cancer - PubMed (original) (raw)

Pterostilbene acts through metastasis-associated protein 1 to inhibit tumor growth, progression and metastasis in prostate cancer

Kun Li et al. PLoS One. 2013.

Abstract

The development of natural product agents with targeted strategies holds promise for enhanced anticancer therapy with reduced drug-associated side effects. Resveratrol found in red wine, has anticancer activity in various tumor types. We reported earlier on a new molecular target of resveratrol, the metastasis-associated protein 1 (MTA1), which is a part of nucleosome remodeling and deacetylation (NuRD) co-repressor complex that mediates gene silencing. We identified resveratrol as a regulator of MTA1/NuRD complex and re-activator of p53 acetylation in prostate cancer (PCa). In the current study, we addressed whether resveratrol analogues also possess the ability to inhibit MTA1 and to reverse p53 deacetylation. We demonstrated that pterostilbene (PTER), found in blueberries, had greater increase in MTA1-mediated p53 acetylation, confirming superior potency over resveratrol as dietary epigenetic agent. In orthotopic PCa xenografts, resveratrol and PTER significantly inhibited tumor growth, progression, local invasion and spontaneous metastasis. Furthermore, MTA1-knockdown sensitized cells to these agents resulting in additional reduction of tumor progression and metastasis. The reduction was dependent on MTA1 signaling showing increased p53 acetylation, higher apoptotic index and less angiogenesis in vivo in all xenografts treated with the compounds, and particularly with PTER. Altogether, our results indicate MTA1 as a major contributor in prostate tumor malignant progression, and support the use of strategies targeting MTA1. Our strong pre-clinical data indicate PTER as a potent, selective and pharmacologically safe natural product that may be tested in advanced PCa.

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Conflict of interest statement

Competing Interests: The authors have declared no competing interests exist.

Figures

Figure 1

Figure 1. Chemical structures of stilbenes.

Resveratrol (Res), _trans_-3,5,4′-trihydroxystilbene; Pterostilbene (PTER), _trans_-3,5-dimethoxystilbene; Trimethoxy-Resveratrol (3M-Res), _trans_-3,5,4′-trimethoxystilbene; Piceatannol (PIC), _trans_-3,5,3′4′-tetrahydroxystilbene; Dimethoxystyrylaniline (DMSA), _trans_-4-(3,5-dimethoxystyryl)aniline; Diacetyl-Resveratrol (2Ac-Res), _trans_-3,5-diacetylstilbene; Triacetyl-Resveratrol (3Ac-Res), _trans_-3,5,4′-triacetylstilbene.

Figure 2

Figure 2. Differential expression of MTA1 in PCa cells analyzed by Western blot.

A. Cell lines represent different stages of PCa progression: RWPE-1, “normal” immortalized prostate epithelial cells; LNCaP, androgen-responsive cells; Du145, androgen-resistant cells; PC3M, aggressive metastatic cells. Cells were grown in RPMI-1640 media containing 10% FBS and antibiotics. 75 µg of protein was separated on 10% gel, transferred to membrane and probed with MTA1 antibodies. β-actin was a loading control. Pterostilbene has the highest potency in inhibiting MTA1. B. Dose-dependent effects of Res/analogues on MTA1 protein levels in LNCaP; in Du145 (C ) and in PC3M (D) cells. (i) cells were treated with 5–100 µM of Res/analogues for 24 hr and analyzed by immunoblotting. (ii) graphical representation of results. The Ctrl is set to 1 and MTA1 level changes are expressed as a percentage of Ctrl. The means±SE of four independent experiments are shown. •p<0.05, #p<0.01, *p<0.001. (iii) effective doses (ED50) were calculated by Chou-Martin method.

Figure 3

Figure 3. Pterostilbene increases MTA1-mediated p53 acetylation in Du145 cells.

Du145-EV and Du145-MTA1shRNA cells (Fig. S1) were treated with 50 µM of Res or PTER for 24 hr and analyzed for MTA1, p53, Ac-p53 by Western blot as described in “Materials and methods”. A representative blot is shown. Quantitation of Ac-p53/p53 ratio was conducted by Image J software and data shown as mean±SEM from three independent experiments.

Figure 4

Figure 4. MTA1-mediated therapeutic activity of resveratrol and pterostilbene in orthotopic PCa xenografts.

Male nude mice were injected orthotopically with Du145-EV-Luc (EV) or Du145-MTA1shRNA-Luc (MTA1shRNA) cells and treated with vehicle (Ctrl), Res or PTER, 50 mg/kg/day, every day, i.p. A. Normalized representative BL images of mice from each group are shown. B, left, Quantitative analysis of tumor light emission in Total Flux (photons/sec/cm2/sr) is plotted against time. The means ± SE are shown (n = 6 at the start), *p = 0.05. Right, log trends for each group are shown. Significant growth inhibition was detected in EV- vs. MTA1shRNA-tumors as groups, **p<0.01 and between EV-Ctrl vs. MTA1shRNA-Res and MTA1shRNA-PTER, ***p<0.001.

Figure 5

Figure 5. Increased p53 acetylation and apoptosis and decreased angiogenesis by resveratrol and pterostilbene are linked to MTA1 inhibition.

Left, representative IHC images of A. Ki-67 (proliferation); B. Ac-p53/p53 (MTA1 signaling); C. M30 (apoptosis); and D. CD31 (angiogenesis) in EV- and MTA1shRNA-tumors are shown. Right, quantification of positively stained cells as percentage of total cells. Data are box plots of randomly chosen five fields analyzed independently by two investigators. Pairwise comparisons, *p<0.05; **p<0.01; ***p<0.001 vs. EV-Ctrl; #p<0.05 and ##p<0.001 vs. MTA1shRNA-Ctrl; +p<0.05 and ++p<0.001, of compounds between EV and MTA1shRNA groups.

Figure 6

Figure 6. Effects of resveratrol and pterostilbene on spontaneous metastasis: involvement of MTA1.

A. BL images of metastasis are shown. Signals detected after prostate removal consisted of metastatic and non-specific signals. Removal of skin and muscles eliminated non-specificity. B. Top, ex vivo images of metastatic organs. Bottom, Validation of metastatic lesions (T) in kidneys (K), liver (Li) and lung/heart (L/H) by H&E staining. C, quantitative analysis of total metastatic Luc signals in Total Flux (photons/sec/cm2/sr). Open circles represent outliers. *p<0.05; **p<0.01; ***p<0.001 are pairwise comparisons vs. EV-Ctrl. D, quantitative analysis of organ-specific metastasis calculated by luciferase signals as Total Flux (photons/sec/cm2/sr). Color-coded histograms of signals for each group are shown. PTER was more effective in inhibiting metastasis in all organs compared to Res in EV-group. In MTA1-knockdown group, Res exhibited more effects by eliminating kidney metastasis.

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References

    1. Bavaresco L (2003) Role of viticultural factors on stilbene concentrations of grapes and wine. Drugs Exp Clin Res 29: 181–187. - PubMed
    1. Aggarwal BB, Bhardwaj A, Aggarwal RS, Seeram NP, Shishodia S, et al. (2004) Role of resveratrol in prevention and therapy of cancer: preclinical and clinical studies. Anticancer Res 24: 2783–2840. - PubMed
    1. Jang M, Cai L, Udeani GO, Slowing KV, Thomas CF, et al. (1997) Cancer chemopreventive activity of resveratrol, a natural product derived from grapes. Science 275: 218–220. - PubMed
    1. Kuwajerwala N, Cifuentes E, Gautam S, Menon M, Barrack ER, et al. (2002) Resveratrol induces prostate cancer cell entry into s phase and inhibits DNA synthesis. Cancer Res 62: 2488–2492. - PubMed
    1. Clement MV, Hirpara JL, Chawdhury SH, Pervaiz S (1998) Chemopreventive agent resveratrol, a natural product derived from grapes, triggers CD95 signaling-dependent apoptosis in human tumor cells. Blood 92: 996–1002. - PubMed

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