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Schwann cell autophagy induced by SAHA, 17-AAG, or clonazepam can reduce bortezomib-induced peripheral neuropathy.

Watanabe T, Nagase K, Chosa M, Tobinai K - Br. J. Cancer (2010)

Bottom Line: A tractable system to evaluate combination drugs for use with bortezomib is essential to enable continuing clinical benefit from this drug.To then monitor aggresome formation as a result of proteasome inhibition and the activation of chaperone-mediated autophagy (CMA), we performed double-labelling immunofluorescent analyses of a cellular aggregation-prone protein marker.Aggresome formation was interrupted by VCR, whereas combination treatments with bortezomib involving suberoylanilide hydroxamic acid, 17-allylamino-17-demethoxy-geldanamycin, or clonazepam appear to facilitate the disposal of unfolded proteins via CMA, inducing HSP70 and lysosome-associated membrane protein type 2A (LAMP-2A).

View Article: PubMed Central - PubMed

Affiliation: Hematology Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. takawata@ncc.go.jp

ABSTRACT

Background: The proteasome inhibitor bortezomib has improved the survival of patients with multiple myeloma but bortezomib-induced peripheral neuropathy (BiPN) has emerged as a serious potential complication of this therapy. Animal studies suggest that bortezomib predominantly causes pathological changes in Schwann cells. A tractable system to evaluate combination drugs for use with bortezomib is essential to enable continuing clinical benefit from this drug.

Methods: Rat schwannoma cells were pretreated with vincristine (VCR), histone deacetylase inhibitors, anticonvulsants, or a heat-shock protein 90 (HSP90) inhibitor. To then monitor aggresome formation as a result of proteasome inhibition and the activation of chaperone-mediated autophagy (CMA), we performed double-labelling immunofluorescent analyses of a cellular aggregation-prone protein marker.

Results: Aggresome formation was interrupted by VCR, whereas combination treatments with bortezomib involving suberoylanilide hydroxamic acid, 17-allylamino-17-demethoxy-geldanamycin, or clonazepam appear to facilitate the disposal of unfolded proteins via CMA, inducing HSP70 and lysosome-associated membrane protein type 2A (LAMP-2A).

Conclusions: This schwannoma model can be used to test BiPN-reducing drugs. The present data suggest that aggresome formation in Schwann cells is a possible mechanism of BiPN, and drugs that induce HSP70 or LAMP-2A have the potential to alleviate this complication. Combination clinical trials are warranted to confirm the relevance of these observations.

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The percentages of round structures adjacent to the nuclei (i.e., aggresomes) and outside the cells were calculated from images showing the colocalisation of PMP22 and γ-tubulin (yellow signals in the far right panel in Figure 2A). These numbers were measured in triplicate and are expressed as the means±s.d. The letters in parentheses under the treatment categories correspond to the images above.
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fig3: The percentages of round structures adjacent to the nuclei (i.e., aggresomes) and outside the cells were calculated from images showing the colocalisation of PMP22 and γ-tubulin (yellow signals in the far right panel in Figure 2A). These numbers were measured in triplicate and are expressed as the means±s.d. The letters in parentheses under the treatment categories correspond to the images above.

Mentions: We next analysed whether treatments with a combination of reagents could reduce aggresome formation. Intriguingly, pretreatment with the histone deacetylase inhibitor (HDACi) SAHA (Figure 2C), the anticonvulsant CZP (Figure 2D), or the HSP90 inhibitor 17-AAG (Figure 2E) caused the appearance of round structures, which were smaller than aggresomes, outside of the cells and with no juxtanuclear aggresomes (Figure 3). In contrast, pretreatment with VPA, also an anticonvulsant and an HDACi, caused the appearance of rounded structures outside of the cells in addition to juxtanuclear aggresomes (Figures 2F and 3).


Schwann cell autophagy induced by SAHA, 17-AAG, or clonazepam can reduce bortezomib-induced peripheral neuropathy.

Watanabe T, Nagase K, Chosa M, Tobinai K - Br. J. Cancer (2010)

The percentages of round structures adjacent to the nuclei (i.e., aggresomes) and outside the cells were calculated from images showing the colocalisation of PMP22 and γ-tubulin (yellow signals in the far right panel in Figure 2A). These numbers were measured in triplicate and are expressed as the means±s.d. The letters in parentheses under the treatment categories correspond to the images above.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2990589&req=5

fig3: The percentages of round structures adjacent to the nuclei (i.e., aggresomes) and outside the cells were calculated from images showing the colocalisation of PMP22 and γ-tubulin (yellow signals in the far right panel in Figure 2A). These numbers were measured in triplicate and are expressed as the means±s.d. The letters in parentheses under the treatment categories correspond to the images above.
Mentions: We next analysed whether treatments with a combination of reagents could reduce aggresome formation. Intriguingly, pretreatment with the histone deacetylase inhibitor (HDACi) SAHA (Figure 2C), the anticonvulsant CZP (Figure 2D), or the HSP90 inhibitor 17-AAG (Figure 2E) caused the appearance of round structures, which were smaller than aggresomes, outside of the cells and with no juxtanuclear aggresomes (Figure 3). In contrast, pretreatment with VPA, also an anticonvulsant and an HDACi, caused the appearance of rounded structures outside of the cells in addition to juxtanuclear aggresomes (Figures 2F and 3).

Bottom Line: A tractable system to evaluate combination drugs for use with bortezomib is essential to enable continuing clinical benefit from this drug.To then monitor aggresome formation as a result of proteasome inhibition and the activation of chaperone-mediated autophagy (CMA), we performed double-labelling immunofluorescent analyses of a cellular aggregation-prone protein marker.Aggresome formation was interrupted by VCR, whereas combination treatments with bortezomib involving suberoylanilide hydroxamic acid, 17-allylamino-17-demethoxy-geldanamycin, or clonazepam appear to facilitate the disposal of unfolded proteins via CMA, inducing HSP70 and lysosome-associated membrane protein type 2A (LAMP-2A).

View Article: PubMed Central - PubMed

Affiliation: Hematology Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. takawata@ncc.go.jp

ABSTRACT

Background: The proteasome inhibitor bortezomib has improved the survival of patients with multiple myeloma but bortezomib-induced peripheral neuropathy (BiPN) has emerged as a serious potential complication of this therapy. Animal studies suggest that bortezomib predominantly causes pathological changes in Schwann cells. A tractable system to evaluate combination drugs for use with bortezomib is essential to enable continuing clinical benefit from this drug.

Methods: Rat schwannoma cells were pretreated with vincristine (VCR), histone deacetylase inhibitors, anticonvulsants, or a heat-shock protein 90 (HSP90) inhibitor. To then monitor aggresome formation as a result of proteasome inhibition and the activation of chaperone-mediated autophagy (CMA), we performed double-labelling immunofluorescent analyses of a cellular aggregation-prone protein marker.

Results: Aggresome formation was interrupted by VCR, whereas combination treatments with bortezomib involving suberoylanilide hydroxamic acid, 17-allylamino-17-demethoxy-geldanamycin, or clonazepam appear to facilitate the disposal of unfolded proteins via CMA, inducing HSP70 and lysosome-associated membrane protein type 2A (LAMP-2A).

Conclusions: This schwannoma model can be used to test BiPN-reducing drugs. The present data suggest that aggresome formation in Schwann cells is a possible mechanism of BiPN, and drugs that induce HSP70 or LAMP-2A have the potential to alleviate this complication. Combination clinical trials are warranted to confirm the relevance of these observations.

Show MeSH
Related in: MedlinePlus