Abstract
BackgroundThough ergosterol peroxide (EP) derived from Neungyi mushrooms (Sarcodon aspratus) was known to have cytotoxic, apoptotic, anti-inflammatory and antimycobacterial effects, the underlying molecular mechanism of EP still remains unclear. Thus, in the present study, the apoptotic mechanism of EP was elucidated in DU 145 prostate cancer cells.MethodsCell viability of prostate cancer cells was measured by MTT assay. To see whether EP induces the apoptosis, FACS, western blot and TUNEL assay were performed. To determine the role of Death receptor (DR) 5 molecules in EP-induced apoptosis in DU 145 prostate cancer cells, the silencing of DR 5 was performed by using siRNAs.ResultsEP showed significant cytotoxicity against DU 145, PC 3, M2182 prostate cancer cells. Also, EP effectively increased the sub G1 population and terminal deoxynucleotidyl transferase DUTP nick end labeling (TUNEL) positive cells in DU 145 prostate cancer cells. Furthermore, western blotting revealed that EP cleaved poly (ADP-ribose) polymerase (PARP) and caspase 8/3, attenuated the expression of fluorescence loss in photobleaching (FLIP), Bcl-XL and Bcl-2 as well as activated Bax, Fas-associated death domain (FADD) and DR 5 in a concentration dependent manner in DU 145 prostate cancer cells. Conversely, caspase 8 inhibitor Z-IETD-FMK blocked the apoptotic ability of EP to cleave PARP and an increase of sub G1 population in DU 145 prostate cancer cells. Likewise, the silencing of DR 5 suppressed the cleavages of PARP induced by EP in DU 145 prostate cancer cells.ConclusionOverall, our findings suggest that ergosterol peroxide induces apoptosis via activation of death receptor 5 and caspase 8/3 in DU 145 prostate cancer cells as a cancer chemopreventive agent or dietary factor.
Highlights
Prostate cancer is the second most frequently diagnosed cancer and the sixth leading cause of cancer death in males worldwide in 2011 [1]
In the present study, the underlying apoptotic mechanism of ergosterol peroxide (EP) was investigated in DU 145 prostate cancer cells targeting extrinsic apoptosis via Death receptor (DR) 5 signaling using MTT assay, cell cycle analysis, transferase DUTP nick end labeling (TUNEL) assay, western blotting and inhibitor study using caspase 8 inhibitor Z-IETD-FMK and siRNA transfection of DR 5
Cytotoxic effect of EP against DU 145 prostate cancer cells EP (Figure 1a) exerted significant cytotoxicity against DU 145 prostate cancer cells compared to non-treated cells
Summary
Prostate cancer is the second most frequently diagnosed cancer and the sixth leading cause of cancer death in males worldwide in 2011 [1]. Sarcodon edible mushroom [12] and its compound ergosterol peroxide (EP) [13], one of β-D-glucan metabolites, were reported to have antitumor activity in several cancers. The underlying molecular mechanism of EP was not fully understood in prostate cancer. In the present study, the underlying apoptotic mechanism of EP was investigated in DU 145 prostate cancer cells targeting extrinsic apoptosis via DR 5 signaling using MTT assay, cell cycle analysis, TUNEL assay, western blotting and inhibitor study using caspase 8 inhibitor Z-IETD-FMK and siRNA transfection of DR 5. Though ergosterol peroxide (EP) derived from Neungyi mushrooms (Sarcodon aspratus) was known to have cytotoxic, apoptotic, anti-inflammatory and antimycobacterial effects, the underlying molecular mechanism of EP still remains unclear. In the present study, the apoptotic mechanism of EP was elucidated in DU 145 prostate cancer cells
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