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Published on: July 30, 2014
Withaferin a alters intermediate filament organization, cell shape and behavior
Boris Grin1, Saleemulla Mahammad, Tatjana Wedig
1Department of Cell and Molecular Biology, Feinberg School of Medicine at Northwestern University, Chicago, Illinois, United States of America. r-goldman@northwestern.edu
Withaferin A (WFA) reorganizes vimentin intermediate filaments (VIF) and affects other cellular structures, potentially leading to apoptosis or senescence. Caution is advised for its use as an anti-cancer agent due to potential organism-wide effects.
Area of Science:
- Cell Biology
- Biochemistry
- Pharmacology
Background:
- Withaferin A (WFA), a compound from Withania somnifera, binds to vimentin, an intermediate filament protein.
- WFA has been proposed as an anti-tumor agent targeting metastatic cells that overexpress vimentin.
Purpose of the Study:
- To investigate the cellular effects of WFA on vimentin intermediate filaments (VIF).
- To determine the specificity and mechanism of WFA's action on intermediate filaments.
- To evaluate the potential of WFA as an anti-cancer agent.
Main Methods:
- Human fibroblasts treated with WFA.
- Analysis of VIF organization, cell shape, motility, and vimentin phosphorylation.
- In vitro assembly assays (analytical ultracentrifugation, viscometry, electron microscopy, sedimentation).
- Testing WFA effects on other intermediate filament networks (peripherin, neurofilament-triplet protein, keratin).
- Assessment of microtubule and actin/microfilament organization.
- Evaluation of WFA-induced apoptosis and senescence.
Main Results:
- WFA treatment reorganizes VIF into perinuclear aggregates in a dose-dependent manner, altering cell shape and decreasing motility.
- WFA increases vimentin phosphorylation at serine-38; a cysteine-328 mutation does not prevent WFA's cellular effects.
- WFA does not affect VIF assembly in vitro and disrupts other intermediate filament networks, including keratin, peripherin, and neurofilament-triplet protein.
- WFA alters microtubule organization and increases stress fibers.
- High WFA doses induce apoptosis, while lower doses cause senescence.
Conclusions:
- WFA affects multiple intermediate filament systems, not just vimentin.
- The proposed vimentin binding site (cysteine-328) is not essential for WFA's cellular effects.
- WFA's broad impact on cellular structures and induction of apoptosis/senescence warrant caution regarding its use as an anti-cancer agent due to potential systemic toxicity.
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