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Class I HDAC inhibitor mocetinostat induces apoptosis by activation of miR-31 expression and suppression of E2F6

View Article: PubMed Central - PubMed

ABSTRACT

The class I selective inhibitor of the histone deacetylases, mocetinostat, has promising antitumor activities in both preclinical studies and the clinical trials. To understand how mocetinostat induces apoptosis, we examined the effects of mocetinostat on miR-31, a proapoptotic microRNA that was previously found to be epigenetically silenced in prostate cancer. We found that miR-31 was significantly upregulated by mocetinostat in prostate cancer cells. Antiapoptotic protein E2F6, the target of miR-31, was decreased by mocetinostat treatment. When miR-31 was blocked with an inhibitor, the ability of mocetinostat to induce apoptosis was reduced. We further demonstrated that mocetinostat enhanced the activity of docetaxel in apoptosis induction. While siRNA knockdown of E2F6 sensitized cancer cells to mocetinostat-induced apoptosis, overexpression of E2F6 blocked mocetinostat-induced apoptosis. In an orthotopic xenograft model, we demonstrated that mocetinostat activated miR-31, decreased E2F6, induced apoptosis, and significantly reduced prostate cancer growth. Importantly, we found that mocetinostat also increased miR-31 expression, decreased E2F6, and induced apoptosis in the primary prostate cancer stem cells. Thus, activation of miR-31 and downregulation of E2F6 constitute an important mechanism in mocetinostat-induced apoptosis in prostate cancer.

No MeSH data available.


Related in: MedlinePlus

Mocetinostat induces apoptosis in the primary prostate cancer stem cells. (a) Prostate cancer stem cells were treated with various doses of mocetinostat for 24 h and apoptosis was analyzed using the Cell Death Detection ElisaPLUS kit. (b) Prostate cancer stem cells were treated with 5 μM mocetinostat for 24 h. Total RNA was isolated and real-time PCR analysis was performed as described in Materials and Methods. (c) Prostate cancer stem cells were treated with 5 μM of mocetinostat for 24 h. Western blotting was performed with the indicated antibodies. The experiments have been repeated three times; data shown are mean values+S.D. (d) Schematic illustration of the role of miR-31 in mocetinostat-induced apoptosis. By inhibiting the class I HDACs, mocetinostat activates miR-31 expression and subsequently decreases E2F6. In the meantime, mocetinostat also increases the proapoptotic protein Bad. As a result, apoptosis is triggered in the prostate cancer cells.
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fig6: Mocetinostat induces apoptosis in the primary prostate cancer stem cells. (a) Prostate cancer stem cells were treated with various doses of mocetinostat for 24 h and apoptosis was analyzed using the Cell Death Detection ElisaPLUS kit. (b) Prostate cancer stem cells were treated with 5 μM mocetinostat for 24 h. Total RNA was isolated and real-time PCR analysis was performed as described in Materials and Methods. (c) Prostate cancer stem cells were treated with 5 μM of mocetinostat for 24 h. Western blotting was performed with the indicated antibodies. The experiments have been repeated three times; data shown are mean values+S.D. (d) Schematic illustration of the role of miR-31 in mocetinostat-induced apoptosis. By inhibiting the class I HDACs, mocetinostat activates miR-31 expression and subsequently decreases E2F6. In the meantime, mocetinostat also increases the proapoptotic protein Bad. As a result, apoptosis is triggered in the prostate cancer cells.

Mentions: It is postulated that cancer stem cells mediate tumor formation, metastasis, and resistance to chemotherapy.31 Thus, it is critical to identify drugs that can eliminate cancer stem cells.32 We tested if mocetinostat is effective against prostate cancer stem cells. As shown in Figure 6a, mocetinostat induced significant levels of apoptosis in patient-derived primary prostate cancer stem cells. Furthermore, mocetinostat increased miR-31 expression (Figure 6b), and decreased E2F6 protein (Figure 6c) in the prostate cancer stem cells. The level of proapoptotic protein Bad was increased by mocetinostat (Figure 6c).


Class I HDAC inhibitor mocetinostat induces apoptosis by activation of miR-31 expression and suppression of E2F6
Mocetinostat induces apoptosis in the primary prostate cancer stem cells. (a) Prostate cancer stem cells were treated with various doses of mocetinostat for 24 h and apoptosis was analyzed using the Cell Death Detection ElisaPLUS kit. (b) Prostate cancer stem cells were treated with 5 μM mocetinostat for 24 h. Total RNA was isolated and real-time PCR analysis was performed as described in Materials and Methods. (c) Prostate cancer stem cells were treated with 5 μM of mocetinostat for 24 h. Western blotting was performed with the indicated antibodies. The experiments have been repeated three times; data shown are mean values+S.D. (d) Schematic illustration of the role of miR-31 in mocetinostat-induced apoptosis. By inhibiting the class I HDACs, mocetinostat activates miR-31 expression and subsequently decreases E2F6. In the meantime, mocetinostat also increases the proapoptotic protein Bad. As a result, apoptosis is triggered in the prostate cancer cells.
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fig6: Mocetinostat induces apoptosis in the primary prostate cancer stem cells. (a) Prostate cancer stem cells were treated with various doses of mocetinostat for 24 h and apoptosis was analyzed using the Cell Death Detection ElisaPLUS kit. (b) Prostate cancer stem cells were treated with 5 μM mocetinostat for 24 h. Total RNA was isolated and real-time PCR analysis was performed as described in Materials and Methods. (c) Prostate cancer stem cells were treated with 5 μM of mocetinostat for 24 h. Western blotting was performed with the indicated antibodies. The experiments have been repeated three times; data shown are mean values+S.D. (d) Schematic illustration of the role of miR-31 in mocetinostat-induced apoptosis. By inhibiting the class I HDACs, mocetinostat activates miR-31 expression and subsequently decreases E2F6. In the meantime, mocetinostat also increases the proapoptotic protein Bad. As a result, apoptosis is triggered in the prostate cancer cells.
Mentions: It is postulated that cancer stem cells mediate tumor formation, metastasis, and resistance to chemotherapy.31 Thus, it is critical to identify drugs that can eliminate cancer stem cells.32 We tested if mocetinostat is effective against prostate cancer stem cells. As shown in Figure 6a, mocetinostat induced significant levels of apoptosis in patient-derived primary prostate cancer stem cells. Furthermore, mocetinostat increased miR-31 expression (Figure 6b), and decreased E2F6 protein (Figure 6c) in the prostate cancer stem cells. The level of proapoptotic protein Bad was increased by mocetinostat (Figure 6c).

View Article: PubMed Central - PubMed

ABSTRACT

The class I selective inhibitor of the histone deacetylases, mocetinostat, has promising antitumor activities in both preclinical studies and the clinical trials. To understand how mocetinostat induces apoptosis, we examined the effects of mocetinostat on miR-31, a proapoptotic microRNA that was previously found to be epigenetically silenced in prostate cancer. We found that miR-31 was significantly upregulated by mocetinostat in prostate cancer cells. Antiapoptotic protein E2F6, the target of miR-31, was decreased by mocetinostat treatment. When miR-31 was blocked with an inhibitor, the ability of mocetinostat to induce apoptosis was reduced. We further demonstrated that mocetinostat enhanced the activity of docetaxel in apoptosis induction. While siRNA knockdown of E2F6 sensitized cancer cells to mocetinostat-induced apoptosis, overexpression of E2F6 blocked mocetinostat-induced apoptosis. In an orthotopic xenograft model, we demonstrated that mocetinostat activated miR-31, decreased E2F6, induced apoptosis, and significantly reduced prostate cancer growth. Importantly, we found that mocetinostat also increased miR-31 expression, decreased E2F6, and induced apoptosis in the primary prostate cancer stem cells. Thus, activation of miR-31 and downregulation of E2F6 constitute an important mechanism in mocetinostat-induced apoptosis in prostate cancer.

No MeSH data available.


Related in: MedlinePlus