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The Anti-Tumor Activity of Succinyl Macrolactin A Is Mediated through the β-Catenin Destruction Complex via the Suppression of Tankyrase and PI3K/Akt.

Regmi SC, Park SY, Kim SJ, Banskota S, Shah S, Kim DH, Kim JA - PLoS ONE (2015)

Bottom Line: SMA significantly reduced the activities of PI3K/Akt, which corresponded with a decrease in GSK3β phosphorylation, an increase in β-catenin phosphorylation, and a reduction in nuclear β-catenin content in HT29 human colon cancer cells.Despite the low potency of SMA against tankyrase activity (IC50 of 50.1 μM and 15.5 μM for tankyrase 1 and 2, respectively) compared to XAV939 (IC50 of 11 nM for tankyrase 1), a selective and potent tankyrase inhibitor, SMA had strong inhibitory effects on β-catenin-dependent TCF/LEF1 transcriptional activity (IC50 of 39.8 nM), which were similar to that of XAV939 (IC50 of 28.1 nM).These results suggest that SMA is a possible candidate as an effective anti-cancer agent alone or in combination with cytotoxic chemotherapeutic drugs, such as 5-FU and cisplatin, and that the mode of action for SMA involves stabilization of the β-catenin destruction complex through inhibition of tankyrase and the PI3K/Akt signaling pathway.

View Article: PubMed Central - PubMed

Affiliation: College of Pharmacy, Yeungnam University, Gyeongsan, Republic of Korea.

ABSTRACT
Accumulated gene mutations in cancer suggest that multi-targeted suppression of affected signaling networks is a promising strategy for cancer treatment. In the present study, we report that 7-O-succinyl macrolactin A (SMA) suppresses tumor growth by stabilizing the β-catenin destruction complex, which was achieved through inhibition of regulatory components associated with the complex. SMA significantly reduced the activities of PI3K/Akt, which corresponded with a decrease in GSK3β phosphorylation, an increase in β-catenin phosphorylation, and a reduction in nuclear β-catenin content in HT29 human colon cancer cells. At the same time, the activity of tankyrase, which inhibits the β-catenin destruction complex by destabilizing the axin level, was suppressed by SMA. Despite the low potency of SMA against tankyrase activity (IC50 of 50.1 μM and 15.5 μM for tankyrase 1 and 2, respectively) compared to XAV939 (IC50 of 11 nM for tankyrase 1), a selective and potent tankyrase inhibitor, SMA had strong inhibitory effects on β-catenin-dependent TCF/LEF1 transcriptional activity (IC50 of 39.8 nM), which were similar to that of XAV939 (IC50 of 28.1 nM). In addition to suppressing the colony forming ability of colon cancer cells in vitro, SMA significantly inhibited tumor growth in CT26 syngenic and HT29 xenograft mouse tumor models. Furthermore, treating mice with SMA in combination with 5-FU in a colon cancer xenograft model or with cisplatin in an A549 lung cancer xenograft model resulted in greater anti-tumor activity than did treatment with the drugs alone. In the xenograft tumor tissues, SMA dose-dependently inhibited nuclear β-catenin along with reductions in GSK3β phosphorylation and increases in axin levels. These results suggest that SMA is a possible candidate as an effective anti-cancer agent alone or in combination with cytotoxic chemotherapeutic drugs, such as 5-FU and cisplatin, and that the mode of action for SMA involves stabilization of the β-catenin destruction complex through inhibition of tankyrase and the PI3K/Akt signaling pathway.

No MeSH data available.


Related in: MedlinePlus

SMA facilitated GSK3β activity by inhibiting PI3K/Akt and tankyrase in HT29 colon cancer cells.(A) Western blot analyses of phosphorylation of PI3K, Akt, GSK3β, and β-catenin and the expression level of axin in SMA- or XAV939-treated HT29 cells. *P<0.05 vs. vehicle-treated controls. (B) Tankyrase activity was measured using the Tankyrase 1 Colorimetric Activity Assay Kit and TNKS2 Histone Ribosylation Colorimetric Assay Kit. XAV939 was used as a positive control. *P<0.05 vs. vehicle-treated control cells. (C) HT29 cells transfected with TCF/LEF-1-Luc reporter gene were pretreated with vehicle or SMA 1 hour prior to being treated with serum.
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pone.0141753.g003: SMA facilitated GSK3β activity by inhibiting PI3K/Akt and tankyrase in HT29 colon cancer cells.(A) Western blot analyses of phosphorylation of PI3K, Akt, GSK3β, and β-catenin and the expression level of axin in SMA- or XAV939-treated HT29 cells. *P<0.05 vs. vehicle-treated controls. (B) Tankyrase activity was measured using the Tankyrase 1 Colorimetric Activity Assay Kit and TNKS2 Histone Ribosylation Colorimetric Assay Kit. XAV939 was used as a positive control. *P<0.05 vs. vehicle-treated control cells. (C) HT29 cells transfected with TCF/LEF-1-Luc reporter gene were pretreated with vehicle or SMA 1 hour prior to being treated with serum.

Mentions: The SMA-induced decrease in total β-catenin levels suggests that SMA enhances the activity of the β-catenin destruction complex. In fact, SMA increased the level of the phosphorylated form of β-catenin (Fig 3A). This increase in β-catenin phosphorylation in SMA-treated cells may have been achieved by increased GSK3β activity due to suppression of PI3K/Akt activity or by increased levels of tankyrase-regulated axin proteins. As expected, there was an inhibitory effect of SMA on PI3K/Akt, and SMA suppressed GSK3β phosphorylation in a concentration-dependent manner (Fig 3A). At the same time, SMA increased axin1 and axin2 levels (Fig 3A). Because axin levels are regulated by tankyrase, we also investigated whether increased axin levels in SMA-treated cells were due to tankyrase inhibition by comparing the effect of SMA to the effect of XAV939, which is a selective and potent tankyrase inhibitor. SMA showed a low level of inhibition of tankyrase enzyme activity (IC50 of 50.1 μM and 15.5 μM for tankyrase 1 and 2, respectively) compared to XAV939 (Fig 3B and Table 2). However, SMA strongly inhibited TCF/LEF transcription activity to almost the same extent as XAV939 (Fig 3C). The IC50 values of SMA and XAV939 on TCF/LEF transcription activity were 39.8 nM and 28.1 nM, respectively (Table 2).


The Anti-Tumor Activity of Succinyl Macrolactin A Is Mediated through the β-Catenin Destruction Complex via the Suppression of Tankyrase and PI3K/Akt.

Regmi SC, Park SY, Kim SJ, Banskota S, Shah S, Kim DH, Kim JA - PLoS ONE (2015)

SMA facilitated GSK3β activity by inhibiting PI3K/Akt and tankyrase in HT29 colon cancer cells.(A) Western blot analyses of phosphorylation of PI3K, Akt, GSK3β, and β-catenin and the expression level of axin in SMA- or XAV939-treated HT29 cells. *P<0.05 vs. vehicle-treated controls. (B) Tankyrase activity was measured using the Tankyrase 1 Colorimetric Activity Assay Kit and TNKS2 Histone Ribosylation Colorimetric Assay Kit. XAV939 was used as a positive control. *P<0.05 vs. vehicle-treated control cells. (C) HT29 cells transfected with TCF/LEF-1-Luc reporter gene were pretreated with vehicle or SMA 1 hour prior to being treated with serum.
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Related In: Results  -  Collection

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pone.0141753.g003: SMA facilitated GSK3β activity by inhibiting PI3K/Akt and tankyrase in HT29 colon cancer cells.(A) Western blot analyses of phosphorylation of PI3K, Akt, GSK3β, and β-catenin and the expression level of axin in SMA- or XAV939-treated HT29 cells. *P<0.05 vs. vehicle-treated controls. (B) Tankyrase activity was measured using the Tankyrase 1 Colorimetric Activity Assay Kit and TNKS2 Histone Ribosylation Colorimetric Assay Kit. XAV939 was used as a positive control. *P<0.05 vs. vehicle-treated control cells. (C) HT29 cells transfected with TCF/LEF-1-Luc reporter gene were pretreated with vehicle or SMA 1 hour prior to being treated with serum.
Mentions: The SMA-induced decrease in total β-catenin levels suggests that SMA enhances the activity of the β-catenin destruction complex. In fact, SMA increased the level of the phosphorylated form of β-catenin (Fig 3A). This increase in β-catenin phosphorylation in SMA-treated cells may have been achieved by increased GSK3β activity due to suppression of PI3K/Akt activity or by increased levels of tankyrase-regulated axin proteins. As expected, there was an inhibitory effect of SMA on PI3K/Akt, and SMA suppressed GSK3β phosphorylation in a concentration-dependent manner (Fig 3A). At the same time, SMA increased axin1 and axin2 levels (Fig 3A). Because axin levels are regulated by tankyrase, we also investigated whether increased axin levels in SMA-treated cells were due to tankyrase inhibition by comparing the effect of SMA to the effect of XAV939, which is a selective and potent tankyrase inhibitor. SMA showed a low level of inhibition of tankyrase enzyme activity (IC50 of 50.1 μM and 15.5 μM for tankyrase 1 and 2, respectively) compared to XAV939 (Fig 3B and Table 2). However, SMA strongly inhibited TCF/LEF transcription activity to almost the same extent as XAV939 (Fig 3C). The IC50 values of SMA and XAV939 on TCF/LEF transcription activity were 39.8 nM and 28.1 nM, respectively (Table 2).

Bottom Line: SMA significantly reduced the activities of PI3K/Akt, which corresponded with a decrease in GSK3β phosphorylation, an increase in β-catenin phosphorylation, and a reduction in nuclear β-catenin content in HT29 human colon cancer cells.Despite the low potency of SMA against tankyrase activity (IC50 of 50.1 μM and 15.5 μM for tankyrase 1 and 2, respectively) compared to XAV939 (IC50 of 11 nM for tankyrase 1), a selective and potent tankyrase inhibitor, SMA had strong inhibitory effects on β-catenin-dependent TCF/LEF1 transcriptional activity (IC50 of 39.8 nM), which were similar to that of XAV939 (IC50 of 28.1 nM).These results suggest that SMA is a possible candidate as an effective anti-cancer agent alone or in combination with cytotoxic chemotherapeutic drugs, such as 5-FU and cisplatin, and that the mode of action for SMA involves stabilization of the β-catenin destruction complex through inhibition of tankyrase and the PI3K/Akt signaling pathway.

View Article: PubMed Central - PubMed

Affiliation: College of Pharmacy, Yeungnam University, Gyeongsan, Republic of Korea.

ABSTRACT
Accumulated gene mutations in cancer suggest that multi-targeted suppression of affected signaling networks is a promising strategy for cancer treatment. In the present study, we report that 7-O-succinyl macrolactin A (SMA) suppresses tumor growth by stabilizing the β-catenin destruction complex, which was achieved through inhibition of regulatory components associated with the complex. SMA significantly reduced the activities of PI3K/Akt, which corresponded with a decrease in GSK3β phosphorylation, an increase in β-catenin phosphorylation, and a reduction in nuclear β-catenin content in HT29 human colon cancer cells. At the same time, the activity of tankyrase, which inhibits the β-catenin destruction complex by destabilizing the axin level, was suppressed by SMA. Despite the low potency of SMA against tankyrase activity (IC50 of 50.1 μM and 15.5 μM for tankyrase 1 and 2, respectively) compared to XAV939 (IC50 of 11 nM for tankyrase 1), a selective and potent tankyrase inhibitor, SMA had strong inhibitory effects on β-catenin-dependent TCF/LEF1 transcriptional activity (IC50 of 39.8 nM), which were similar to that of XAV939 (IC50 of 28.1 nM). In addition to suppressing the colony forming ability of colon cancer cells in vitro, SMA significantly inhibited tumor growth in CT26 syngenic and HT29 xenograft mouse tumor models. Furthermore, treating mice with SMA in combination with 5-FU in a colon cancer xenograft model or with cisplatin in an A549 lung cancer xenograft model resulted in greater anti-tumor activity than did treatment with the drugs alone. In the xenograft tumor tissues, SMA dose-dependently inhibited nuclear β-catenin along with reductions in GSK3β phosphorylation and increases in axin levels. These results suggest that SMA is a possible candidate as an effective anti-cancer agent alone or in combination with cytotoxic chemotherapeutic drugs, such as 5-FU and cisplatin, and that the mode of action for SMA involves stabilization of the β-catenin destruction complex through inhibition of tankyrase and the PI3K/Akt signaling pathway.

No MeSH data available.


Related in: MedlinePlus