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Discovery of a small molecule targeting SET-PP2A interaction to overcome BCR-ABLT315I mutation of chronic myeloid leukemia.

Wang S, Xie W, Wang D, Peng Z, Zheng Y, Liu N, Dai W, Wang Y, Wang Z, Yang Y, Chen Y - Oncotarget (2015)

Bottom Line: In addition, knocking-down SET expression decreases tumor cell sensitivity to TGI1002.Moreover, TGI1002 significantly inhibits tumor growth and prolongs survival of xenografted mice implanted with BaF3-p210T315I cells.These findings demonstrate that TGI1002 is a novel SET inhibitor with important therapeutic potential for the treatment of drug-resistant CML.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Natural Medicines and Laboratory of Chemical Biology, China Pharmaceutical University, Nanjing, China.

ABSTRACT
Despite the great success in using tyrosine kinase inhibitors (TKIs) to treat chronic myeloid leukemia (CML), the frequent development of multi-drug resistance, particularly the T315I mutation of BCR-ABL, remains a challenging issue. Enhancement of protein phosphatase 2A (PP2A) activity by dissociating its endogenous inhibitor SET is an effective approach to combat TKI-based resistance. Here, we report the identification of a novel 2-phenyloxypyrimidine compound TGI1002 to specifically disrupt SET-PP2A interaction. By binding to SET, TGI1002 inhibits SET-PP2A interaction and increases PP2A activity. In addition, knocking-down SET expression decreases tumor cell sensitivity to TGI1002. TGI1002 treatments also markedly increase dephosphorylation of BCR-ABL. Moreover, TGI1002 significantly inhibits tumor growth and prolongs survival of xenografted mice implanted with BaF3-p210T315I cells. These findings demonstrate that TGI1002 is a novel SET inhibitor with important therapeutic potential for the treatment of drug-resistant CML.

No MeSH data available.


Related in: MedlinePlus

TGI1002 disrupts SET-PP2Ac association and activates PP2A in vitro(A) TGI1002 inhibited SET-PP2Ac interaction in K562 cells. K562 cells were incubated with TGI1002 for 24 h. SET and PP2Ac protein complexes were immunoprecipitated and analyzed for SET and PP2Ac co-immunoprecipitation. TGI1002 showed inhibition of SET-PP2Ac complex formation. (B) TGI1002 treatment activated PP2A in K562 cells. K562 cells were treated with TGI1002 and the activity of PP2A was measured using an immunoprecipitation phosphatase assay. PP2A activity was significantly increased compared to untreated control. (C) TGI1002 inhibited SET-PP2Ac interaction in murine BaF3-p210T315I cells. SET and PP2Ac protein complexes were immunoprecipitated and analyzed for SET and PP2Ac co-immunoprecipitation. TGI1002 showed inhibition of SET-PP2Ac complex formation. (D) TGI1002 treatment activated PP2A in murine BaF3-p210T315I cells. Data in (B) and (D) are presented as mean ± s.d. (n= 3). *, P < 0.05 and **, P < 0.01 compared to untreated; #, P < 0.05 and ##, P < 0.01 compared to OA treatment.
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Figure 4: TGI1002 disrupts SET-PP2Ac association and activates PP2A in vitro(A) TGI1002 inhibited SET-PP2Ac interaction in K562 cells. K562 cells were incubated with TGI1002 for 24 h. SET and PP2Ac protein complexes were immunoprecipitated and analyzed for SET and PP2Ac co-immunoprecipitation. TGI1002 showed inhibition of SET-PP2Ac complex formation. (B) TGI1002 treatment activated PP2A in K562 cells. K562 cells were treated with TGI1002 and the activity of PP2A was measured using an immunoprecipitation phosphatase assay. PP2A activity was significantly increased compared to untreated control. (C) TGI1002 inhibited SET-PP2Ac interaction in murine BaF3-p210T315I cells. SET and PP2Ac protein complexes were immunoprecipitated and analyzed for SET and PP2Ac co-immunoprecipitation. TGI1002 showed inhibition of SET-PP2Ac complex formation. (D) TGI1002 treatment activated PP2A in murine BaF3-p210T315I cells. Data in (B) and (D) are presented as mean ± s.d. (n= 3). *, P < 0.05 and **, P < 0.01 compared to untreated; #, P < 0.05 and ##, P < 0.01 compared to OA treatment.

Mentions: Given that SET is an endogenous inhibitor of the multimeric Ser/Thr protein phosphatase PP2A [18, 19], we next investigated if the binding of TGI1002 with SET protein disrupts the association of SET and PP2A and consequently affect PP2A activity. Co-immunoprecipitation assay showed a trend of decrease on the association between SET and PP2A in K562 cells without significant alteration of SET expression in the presence of TGI1002 (Figure 4A). Meanwhile, there was a tendency on the decrease of catalytic subunit of PP2A (PP2Ac) phosphorylation although lower doses did not show obvious changes (Figure 4A). In addition, PP2A activity, as determined by PP2Ac immunoprecipitation phosphatase assay, was enhanced by 144.67 ± 5.51% after TGI1002-treatment (10 μM, 24 h) in K562 cells compared to untreated cells (Figure 4B). In the presence of specific PP2A inhibitor okadaic acid (OA) [19], PP2A activity decreased significantly compared to control. However, upon TGI1002 treatments, the inhibition of PP2A by OA was reduced in a dose-dependent manner in K562 cells (Figure 4B), further confirming that the increase of PP2A activity was a result of the interaction between TGI1002 and SET. When we treated the drug-resistant BaF3-p210T315I cells, similar to non-resistant K562 cells, TGI1002 disrupted the association of SET with PP2A, down-regulated phosphorylated PP2Ac, increased PP2A activity and antagonized the inhibitory effects of OA on PP2A (Figure 4C and 4D), suggesting that TGI1002 may be active and useful for the treatment of drug-resistant CML with T315I mutation of BCR-ABL.


Discovery of a small molecule targeting SET-PP2A interaction to overcome BCR-ABLT315I mutation of chronic myeloid leukemia.

Wang S, Xie W, Wang D, Peng Z, Zheng Y, Liu N, Dai W, Wang Y, Wang Z, Yang Y, Chen Y - Oncotarget (2015)

TGI1002 disrupts SET-PP2Ac association and activates PP2A in vitro(A) TGI1002 inhibited SET-PP2Ac interaction in K562 cells. K562 cells were incubated with TGI1002 for 24 h. SET and PP2Ac protein complexes were immunoprecipitated and analyzed for SET and PP2Ac co-immunoprecipitation. TGI1002 showed inhibition of SET-PP2Ac complex formation. (B) TGI1002 treatment activated PP2A in K562 cells. K562 cells were treated with TGI1002 and the activity of PP2A was measured using an immunoprecipitation phosphatase assay. PP2A activity was significantly increased compared to untreated control. (C) TGI1002 inhibited SET-PP2Ac interaction in murine BaF3-p210T315I cells. SET and PP2Ac protein complexes were immunoprecipitated and analyzed for SET and PP2Ac co-immunoprecipitation. TGI1002 showed inhibition of SET-PP2Ac complex formation. (D) TGI1002 treatment activated PP2A in murine BaF3-p210T315I cells. Data in (B) and (D) are presented as mean ± s.d. (n= 3). *, P < 0.05 and **, P < 0.01 compared to untreated; #, P < 0.05 and ##, P < 0.01 compared to OA treatment.
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Figure 4: TGI1002 disrupts SET-PP2Ac association and activates PP2A in vitro(A) TGI1002 inhibited SET-PP2Ac interaction in K562 cells. K562 cells were incubated with TGI1002 for 24 h. SET and PP2Ac protein complexes were immunoprecipitated and analyzed for SET and PP2Ac co-immunoprecipitation. TGI1002 showed inhibition of SET-PP2Ac complex formation. (B) TGI1002 treatment activated PP2A in K562 cells. K562 cells were treated with TGI1002 and the activity of PP2A was measured using an immunoprecipitation phosphatase assay. PP2A activity was significantly increased compared to untreated control. (C) TGI1002 inhibited SET-PP2Ac interaction in murine BaF3-p210T315I cells. SET and PP2Ac protein complexes were immunoprecipitated and analyzed for SET and PP2Ac co-immunoprecipitation. TGI1002 showed inhibition of SET-PP2Ac complex formation. (D) TGI1002 treatment activated PP2A in murine BaF3-p210T315I cells. Data in (B) and (D) are presented as mean ± s.d. (n= 3). *, P < 0.05 and **, P < 0.01 compared to untreated; #, P < 0.05 and ##, P < 0.01 compared to OA treatment.
Mentions: Given that SET is an endogenous inhibitor of the multimeric Ser/Thr protein phosphatase PP2A [18, 19], we next investigated if the binding of TGI1002 with SET protein disrupts the association of SET and PP2A and consequently affect PP2A activity. Co-immunoprecipitation assay showed a trend of decrease on the association between SET and PP2A in K562 cells without significant alteration of SET expression in the presence of TGI1002 (Figure 4A). Meanwhile, there was a tendency on the decrease of catalytic subunit of PP2A (PP2Ac) phosphorylation although lower doses did not show obvious changes (Figure 4A). In addition, PP2A activity, as determined by PP2Ac immunoprecipitation phosphatase assay, was enhanced by 144.67 ± 5.51% after TGI1002-treatment (10 μM, 24 h) in K562 cells compared to untreated cells (Figure 4B). In the presence of specific PP2A inhibitor okadaic acid (OA) [19], PP2A activity decreased significantly compared to control. However, upon TGI1002 treatments, the inhibition of PP2A by OA was reduced in a dose-dependent manner in K562 cells (Figure 4B), further confirming that the increase of PP2A activity was a result of the interaction between TGI1002 and SET. When we treated the drug-resistant BaF3-p210T315I cells, similar to non-resistant K562 cells, TGI1002 disrupted the association of SET with PP2A, down-regulated phosphorylated PP2Ac, increased PP2A activity and antagonized the inhibitory effects of OA on PP2A (Figure 4C and 4D), suggesting that TGI1002 may be active and useful for the treatment of drug-resistant CML with T315I mutation of BCR-ABL.

Bottom Line: In addition, knocking-down SET expression decreases tumor cell sensitivity to TGI1002.Moreover, TGI1002 significantly inhibits tumor growth and prolongs survival of xenografted mice implanted with BaF3-p210T315I cells.These findings demonstrate that TGI1002 is a novel SET inhibitor with important therapeutic potential for the treatment of drug-resistant CML.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Natural Medicines and Laboratory of Chemical Biology, China Pharmaceutical University, Nanjing, China.

ABSTRACT
Despite the great success in using tyrosine kinase inhibitors (TKIs) to treat chronic myeloid leukemia (CML), the frequent development of multi-drug resistance, particularly the T315I mutation of BCR-ABL, remains a challenging issue. Enhancement of protein phosphatase 2A (PP2A) activity by dissociating its endogenous inhibitor SET is an effective approach to combat TKI-based resistance. Here, we report the identification of a novel 2-phenyloxypyrimidine compound TGI1002 to specifically disrupt SET-PP2A interaction. By binding to SET, TGI1002 inhibits SET-PP2A interaction and increases PP2A activity. In addition, knocking-down SET expression decreases tumor cell sensitivity to TGI1002. TGI1002 treatments also markedly increase dephosphorylation of BCR-ABL. Moreover, TGI1002 significantly inhibits tumor growth and prolongs survival of xenografted mice implanted with BaF3-p210T315I cells. These findings demonstrate that TGI1002 is a novel SET inhibitor with important therapeutic potential for the treatment of drug-resistant CML.

No MeSH data available.


Related in: MedlinePlus