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Combination of JAK2 and HSP90 inhibitors: an effective therapeutic option in drug-resistant chronic myelogenous leukemia

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ABSTRACT

Recent studies suggest that JAK2 serves as a novel therapeutic target in Bcr-Abl+ chronic myelogenous leukemia (CML). We have reported the existence of an HSP90- associated high molecular weight network complex (HMWNC) that is composed of HSP90 client proteins BCR-ABL, JAK2, and STAT3 in wild type Bcr-Abl+ leukemic cells. Here we showed that the HSP90-HMWNC is present in leukemia cells from CML patients in blast stage, and in Imatinib (IM)-resistant 32Dp210 (T315I) leukemia cells. We found that the HSP90-HMWNC could be disassembled by depleting JAK2 with either Jak2-specific shRNA or treatment with JAK2 inhibitors (TG101209 or Ruxolitinib) and HSP90 inhibitor (AUY922). Combinational treatment with JAK2 and HSP90 inhibitors diminished the activation of BCR-ABL, JAK2 and its downstream targets. As a result, the IM-resistant 32Dp210 T315I cells underwent apoptosis. When administered in mice bearing 32Dp210 T315I leukemia, combinational therapy using Ruxolitinib and AUY922 prolonged the survival significantly. Thus, a combination of JAK2 and HSP90 inhibitors could be a powerful strategy for the treatment of CML, especially in IM-resistant patients.

No MeSH data available.


Combined treatment of JAK2 and HSP90 inhibitors in Bcr-Abl+ IM-resistant cells induced apoptosis(A) 32Dp210 T315I cells were treated with TG101209 (100nM) and AUY922 (20nM) for 0-16hr. Cell lysate were probed with anti-PARP antibodies to indicate the apoptosis levels as measured by the presence of cleaved PARP; (B) Induction of apoptosis was enhanced in 32Dp210 T315I cells when treated with both TG101209 and AUY922 for 16hr; (C) A different JAK inhibitor Ruxolitinib (0-20μM) and showed similar synergistic effect with AUY922 (0-20nM) in inducing apoptosis in 32Dp210 T315I cells.
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Figure 3: Combined treatment of JAK2 and HSP90 inhibitors in Bcr-Abl+ IM-resistant cells induced apoptosis(A) 32Dp210 T315I cells were treated with TG101209 (100nM) and AUY922 (20nM) for 0-16hr. Cell lysate were probed with anti-PARP antibodies to indicate the apoptosis levels as measured by the presence of cleaved PARP; (B) Induction of apoptosis was enhanced in 32Dp210 T315I cells when treated with both TG101209 and AUY922 for 16hr; (C) A different JAK inhibitor Ruxolitinib (0-20μM) and showed similar synergistic effect with AUY922 (0-20nM) in inducing apoptosis in 32Dp210 T315I cells.

Mentions: Surprisingly, we observed that the proliferating rate of K562 cells with reduced JAK2 expression by Jak2-specific shRNA was not apparently different from the parental cells, which may be due to the incomplete depletion of JAK2 (data not shown). However, when 32Dp210 T315I cells were treated with both TG101209 (100nM) and AUY922 (10-20nM) for 3-16hrs, the amount of apoptotic cells were gradually increased as measured by the level of cleaved PARP (Figure 3A). Furthermore, either inhibitors alone was less capable to induce apoptosis in 32Dp210 T315I cells, compared to combinational treatment with both TG101209 and AUY922 (Figure 3B), suggesting the synergistic effect of using both JAK2 and HSP90 inhibitors at a relatively low concentration to kill IM-resistant leukemia cells. This additive effect in inducing apoptosis in 32Dp210 T315I cells was also observed when using a different JAK1/2 inhibitor Ruxolitinib with TG101209, albeit at a higher amount of Ruxolitinib (10 or 20μM) (Figure 3C). This result may have a clinical implication to reduce the side effects of using the JAK inhibitor at a higher dose.


Combination of JAK2 and HSP90 inhibitors: an effective therapeutic option in drug-resistant chronic myelogenous leukemia
Combined treatment of JAK2 and HSP90 inhibitors in Bcr-Abl+ IM-resistant cells induced apoptosis(A) 32Dp210 T315I cells were treated with TG101209 (100nM) and AUY922 (20nM) for 0-16hr. Cell lysate were probed with anti-PARP antibodies to indicate the apoptosis levels as measured by the presence of cleaved PARP; (B) Induction of apoptosis was enhanced in 32Dp210 T315I cells when treated with both TG101209 and AUY922 for 16hr; (C) A different JAK inhibitor Ruxolitinib (0-20μM) and showed similar synergistic effect with AUY922 (0-20nM) in inducing apoptosis in 32Dp210 T315I cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4979592&req=5

Figure 3: Combined treatment of JAK2 and HSP90 inhibitors in Bcr-Abl+ IM-resistant cells induced apoptosis(A) 32Dp210 T315I cells were treated with TG101209 (100nM) and AUY922 (20nM) for 0-16hr. Cell lysate were probed with anti-PARP antibodies to indicate the apoptosis levels as measured by the presence of cleaved PARP; (B) Induction of apoptosis was enhanced in 32Dp210 T315I cells when treated with both TG101209 and AUY922 for 16hr; (C) A different JAK inhibitor Ruxolitinib (0-20μM) and showed similar synergistic effect with AUY922 (0-20nM) in inducing apoptosis in 32Dp210 T315I cells.
Mentions: Surprisingly, we observed that the proliferating rate of K562 cells with reduced JAK2 expression by Jak2-specific shRNA was not apparently different from the parental cells, which may be due to the incomplete depletion of JAK2 (data not shown). However, when 32Dp210 T315I cells were treated with both TG101209 (100nM) and AUY922 (10-20nM) for 3-16hrs, the amount of apoptotic cells were gradually increased as measured by the level of cleaved PARP (Figure 3A). Furthermore, either inhibitors alone was less capable to induce apoptosis in 32Dp210 T315I cells, compared to combinational treatment with both TG101209 and AUY922 (Figure 3B), suggesting the synergistic effect of using both JAK2 and HSP90 inhibitors at a relatively low concentration to kill IM-resistant leukemia cells. This additive effect in inducing apoptosis in 32Dp210 T315I cells was also observed when using a different JAK1/2 inhibitor Ruxolitinib with TG101209, albeit at a higher amount of Ruxolitinib (10 or 20μM) (Figure 3C). This result may have a clinical implication to reduce the side effects of using the JAK inhibitor at a higher dose.

View Article: PubMed Central - PubMed

ABSTRACT

Recent studies suggest that JAK2 serves as a novel therapeutic target in Bcr-Abl+ chronic myelogenous leukemia (CML). We have reported the existence of an HSP90- associated high molecular weight network complex (HMWNC) that is composed of HSP90 client proteins BCR-ABL, JAK2, and STAT3 in wild type Bcr-Abl+ leukemic cells. Here we showed that the HSP90-HMWNC is present in leukemia cells from CML patients in blast stage, and in Imatinib (IM)-resistant 32Dp210 (T315I) leukemia cells. We found that the HSP90-HMWNC could be disassembled by depleting JAK2 with either Jak2-specific shRNA or treatment with JAK2 inhibitors (TG101209 or Ruxolitinib) and HSP90 inhibitor (AUY922). Combinational treatment with JAK2 and HSP90 inhibitors diminished the activation of BCR-ABL, JAK2 and its downstream targets. As a result, the IM-resistant 32Dp210 T315I cells underwent apoptosis. When administered in mice bearing 32Dp210 T315I leukemia, combinational therapy using Ruxolitinib and AUY922 prolonged the survival significantly. Thus, a combination of JAK2 and HSP90 inhibitors could be a powerful strategy for the treatment of CML, especially in IM-resistant patients.

No MeSH data available.