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. 2021 May 12;9(5):538.
doi: 10.3390/biomedicines9050538.

Eggmanone Effectively Overcomes Prostate Cancer Cell Chemoresistance

Chen Xie  1 , Pen-Jen Lin  2 , Jijun Hao  1   2
Affiliations

Eggmanone Effectively Overcomes Prostate Cancer Cell Chemoresistance

Chen Xie et al. Biomedicines. .

Abstract

Prostate cancer chemoresistance is a major therapeutic problem, and the underlying mechanism is not well understood and effective therapies to overcome this problem are not available. Phosphodiesterase-4 (PDE4), a main intracellular enzyme for cAMP hydrolysis, has been previously shown to involve in the early chemo-sensitive prostate cancer cell proliferation and progression, but its role in the more-advanced chemo-resistant prostate cancer is completely unknown. Here we found that the expression of PDE4 subtype, PDE4D, is highly elevated in the chemo-resistant prostate cancer cells (DU145-TxR and PC3-TxR) in comparison to the chemo-sensitive prostate cancer cells (DU145 and PC3). Inhibition of PDE4D with a potent and selective PDED4 inhibitor, Eggmanone, effectively decreases the invasion and proliferation as well as induces cell death of the chemo-resistant prostate cancer cells (DU145-TxR and PC3-TxR). These results were confirmed by siRNA knockdown of PDE4D. We and colleagues previously reported that Eggmanone can effectively blocked sonic Hedgehog signaling via PDE4D inhibition, and here our study suggests that that Eggmanone downregulated proliferation of the chemo-resistant prostate cancer cells via sonic Hedgehog signaling. In addition, Eggmanone treatment dose-dependently increases docetaxel cytotoxicity to DU145-TxR and PC3-TxR. As cancer stem cells (CSCs) are known to be implicated in cancer chemoresistance, we further examined Eggmanone impacts on CSC-like properties in the chemo-resistant prostate cancer cells. Our study shows that Eggmanone effectively down-regulates the expression of CSCs' marker genes Nanog and ABC sub-family G member 2 (ABCG2) and attenuates sphere formation in DU145-TxR and PC3-TxR cells. In summary, our work shows that Eggmanone effectively overcomes the chemoresistance of prostate cancer cells presumably through sonic Hedgehog signaling and targeting CSCs, suggesting that Eggmanone may serve as a novel agent for chemo-resistant prostate cancer.

Keywords: Eggmanone; Phosphodiesterase-4; cancer stem cells; chemoresistance; prostate cancer.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
PDED4 expression is highly upregulated in chemo-resistant prostate cancer cells. (A) and (B) mRNA expression of all four PDE4 subtypes (PDE4A, PDE4B, PDE4C and PDE4D) was examined by RT-PCT in the chemo-sensitive prostate cancer DU145 and PC3 cells and the chemo-resistant prostate cancer DU145-TxR and PC3-TxR cells. The result showed that only PDE4D expression was highly upregulated in the chemo-resistant prostate cancer cell lines. RT-PC result was represented as mean relative quantity (RQ) ± SEM (n = 3, * p < 0.05, ** p < 0.01). (C) Western blotting result confirmed that PDE4D expression was elevated in the chemo-resistant prostate cancer DU145-TxR and PC3-TxR cells in comparison to the chemo-sensitive prostate cancer DU145 and PC3 cells.
Figure 2
Figure 2
Eggmanone decreases invasion but not migration of chemo-resistant prostate cancer cells. (A,B) Effects of Eggmanone (EGM, 3 µM), Docetaxel (DTX, 1 nM) and their combination (3 µM EGM/1 nM DTX) on invasion of the chemo-resistant prostate cancer DU145-TxR and PC3-TxR cells were determined using the modified Boyden chamber assay in a 24-Multiwell Insert System (8 µM membrane, BD Biosciences) coated with Matrigel. The cells were treated for 72 h, and the invading cell percentages were normalized to the DMSO vehicle treated controls. (C,D) Effects of Eggmanone (EGM, 3 µM), Docetaxel (DTX, 1 nM) and their combination (3 µM EGM/1 nM DTX) on migration of the chemo-resistant prostate cancer DU145-TxR and PC3-TxR cells were determined using the scratch-wound assay. Cell migrations were quantified by the gap distances after 22-hr treatment normalized with the initial gap distances (n = 3, * p < 0.05, ** p < 0.01).
Figure 3
Figure 3
Eggmanone reduces proliferation and induces death of chemo-resistant prostate cancer cells. (A) The chemo-sensitive prostate cancer DU145 and PC3 cells and the chemo-resistant prostate cancer DU145-TxR and PC3-TxR cells were treated with DMSO vehicle, docetaxel at 1 nM and 10 nM concentrations for 72 h, respectively. The cell viability (%) was normalized with DMSO vehicle treated cells, and the result indicated that docetaxel treatment dramatically down-regulated cell viabilities of the chemo-sensitive DU145 and PC3 but not chemo-resistant DU145-TxR and PC3-TxR cells (up to 10 nM). (B) The chemo-sensitive prostate cancer DU145 and PC3 cells and the chemo-resistant prostate cancer DU145-TxR and PC3-TxR cells were treated with DMSO vehicle, Eggmanone at 1 µM, 2 µM and 3 µM concentrations for 72 h. The cell viability (%) was normalized with DMSO vehicle treated cells, and the result indicated that Eggmanone treatment dramatically down-regulated cell viabilities of both chemo-sensitive and chemo-resistant prostate cancer cells (C) DU145-TxR and (D) PC3-TxR cells were treated with DMSO vehicle, 3 µM Eggmanone, siRNA control and siRNA PDE4D, and the cell viability was assayed after 72 h. (E) RT-PCR result indicates that PDE4D was effectively knock downed (approximately 75% gene knockdown for DU-145-TxR and 58% for PC3-TxR). (F) The chemo-sensitive prostate cancer DU145 and PC3 cells and the chemo-sensitive prostate cancer DU145 and PC3 cells and the chemo-resistant prostate cancer DU145-TxR and PC3-TxR cells were treated with DMSO vehicle, Eggmanone at 3µM concentrations for 72 h, the cells were harvested for cell death assay using Trypan Blue staining. The result showed that 3 µM Eggmanone significantly reduced cell deaths in both chemo-sensitive and chemo-resistant prostate cancer cells (n = 3, ** p < 0.01). For each experiment (n = 3, * p < 0.05, ** p < 0.01, *** p < 0.001).
Figure 4
Figure 4
Eggmanone reduces the proliferation of chemo-resistant prostate cancer cells through sonic Hedgehog pathway. (A) The chemo-resistant prostate cancer DU145-TxR and (B) PC3-TxR cells were treated with DMSO vehicle, 3 µM Eggmanone, 200 ng/mL sonic Hedgehog (shh) ligand, 200 ng/mL shh with 3 µM Eggmanone (EGM), 200 ng/mL shh with siRNA control and 200 ng/mL shh with PDE4D knockdown with siRNA, respectively, for 72 h. The cell viability (%) was normalized with DMSO vehicle treated cells, and the result indicated that shh increases the chemo-resistant prostate cancer cell viability which is suppressed by PDE4D knockdown (n = 3, * p < 0.05, ** p < 0.01).
Figure 5
Figure 5
Treatment with the combination of Eggmanone and docetaxel dramatically overcomes prostate cancer cell chemo-resistance. (A) the chemo-resistant prostate cancer DU145-TxR cells were treated with both Eggmanone (1 µM, 2 µM and 3 µM) and docetaxel (0, 0.1, 0.33,1, 3.3, 10, 33.3, 100 and 200 nM) for 72 h. The control cell viability (no DTX) was designated as 100%. Cell viabilities were normalized to the control (no DTX) and cell viability at different DTX concentrations with 1 µM, 2 µM or 3 µM Eggmanone was plotted. The result showed that Eggmanone dose-dependently increased cytotoxicity of docetaxel to chemo-resistant DU145-TxR. (B) The chemo-resistant prostate cancer PC3-TxR cells were treated with both Eggmanone (1 µM, 2 µM and 3 µM) and docetaxel (0, 0.1, 0.33,1, 3.3, 10, 33.3, 100 and 200 nM for 72 h. The control cell viability (no DTX) was designated as 100%. Cell viabilities were normalized to the control (no DTX) and cell viability at different DTX concentrations with 1 µM, 2 µM or 3 µM Eggmanone was plotted. The result showed that Eggmanone dose-dependently increased cytotoxicity of docetaxel to chemo-resistant PC3-TxR.
Figure 6
Figure 6
Eggmanone inhibits sphere formation in chemo-resistant prostate cancer cells.Sphere formation assay in chemo-resistant DU145-TxR and PC3-TxR cells treated with vehicle DMSO, 1 nM Docetaxel (DTX) and 3 µM Eggmanone (EGM). (* p < 0.05, ** p < 0.01).
Figure 7
Figure 7
Eggmanone attenuates the expression of CSCs’ markers in chemo-resistant prostate cancer cells. (A) RT-PCR shows that mRNA of Nanog is statistically significantly down-regulated in chemo-resistant DU145-TxR and PC3-TxR cells treated with 3 µM Eggmanone (EGM). (B) RT-PCR shows that mRNA of ABCG2 is statistically significantly decreased in chemo-resistant DU145-TxR and PC3-TxR cells treated with 3 µM Eggmanone (EGM). RT-PC result was represented as mean relative quantity (RQ) ± SEM (n = 3, * p < 0.05, ** p < 0.01).
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References

    1. Bray F., Ferlay J., Soerjomataram I., Siegel R.L., Torre L.A., Jemal A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J. Clin. 2018;68:394–424. doi: 10.3322/caac.21492. - DOI - PubMed
    1. Bishr M., Saad F. Overview of the latest treatments for castration-resistant prostate cancer. Nat. Rev. Urol. 2013;10:522–528. doi: 10.1038/nrurol.2013.137. - DOI - PubMed
    1. Huggins C. The Hormone-Dependent Cancers. JAMA. 1963;186:481–483. doi: 10.1001/jama.1963.63710050009008. - DOI - PubMed
    1. Huggins C., Hodges C.V. Studies on Prostatic Cancer: I. The Effect of Castration, of Estrogen and of Androgen Injection on Serum Phosphatases in Metastatic Carcinoma of the Prostate. J. Urol. 2002;168:9–12. doi: 10.1016/S0022-5347(05)64820-3. - DOI - PubMed
    1. Tannock I.F., De Wit R., Berry W.R., Horti J., Pluzanska A., Chi K.N., Oudard S., Theodore C., James N.D., Turesson I., et al. Docetaxel plus Prednisone or Mitoxantrone plus Prednisone for Advanced Prostate Cancer. N. Engl. J. Med. 2004;351:1502–1512. doi: 10.1056/NEJMoa040720. - DOI - PubMed