Persistent inhibition of pore-based cell migration by sub-toxic doses of miuraenamide, an actin filament stabilizer

Abstract

Opposed to tubulin-binding agents, actin-binding small molecules have not yet become part of clinical tumor treatment, most likely due to the fear of general cytotoxicity. Addressing this problem, we investigated the long-term efficacy of sub-toxic doses of miuraenamide, an actin filament stabilizing natural compound, on tumor cell (SKOV3) migration. No cytotoxic effects or persistent morphological changes occurred at a concentration of miuraenamide of 20 nM. After 72 h treatment with this concentration, nuclear stiffness was increased, causing reduced migration through pores in a Boyden chamber, while cell migration and chemotaxis per se were unaltered. A concomitant time-resolved proteomic approach showed down regulation of a protein cluster after 56 h treatment. This cluster correlated best with the Wnt signaling pathway. A further analysis of the actin associated MRTF/SRF signaling showed a surprising reduction of SRF-regulated proteins. In contrast to acute effects of actin-binding compounds on actin at high concentrations, long-term low-dose treatment elicits much more subtle but still functionally relevant changes beyond simple destruction of the cytoskeleton. These range from biophysical parameters to regulation of protein expression, and may help to better understand the complex biology of actin, as well as to initiate alternative regimes for the testing of actin-targeting drugs.

Actin stabilizing compounds show specific biological effects due to their binding mode

“…These results indicate that MiuA has an overall effect on both cell motility and directionality of the movement, both in a simple 2D and in more physiological 3D environments. The reduced velocity in the 3D system could be explained by the cells having a reduced ability to squeeze through a small meshwork, as we have previously described 11 .…”

“…The myxobacterial compound miuraenamide A (MiuA) 25 is also structurally related to these compounds, and has turned out to have a functional profile similar to phalloidin or jasplakinolide (enhanced polymerization and stabilization, cell morphology and cytotoxicity) 9,10 . We have previously used MiuA as a bona fide actin polymerizing compound in cellular studies, and have shown effects on cell migration and transcriptional activity that can be ascribed to its actin stabilizing nature 11,26 . In the present study we established dose response curves for MiuA on proliferation in primary endothelial cells (HUVECs), which are similar to those in tumor cell lines 9,11 , and lie in the same range as those for jasplakinolide 27 .…”

“…We have previously used MiuA as a bona fide actin polymerizing compound in cellular studies, and have shown effects on cell migration and transcriptional activity that can be ascribed to its actin stabilizing nature 11,26 . In the present study we established dose response curves for MiuA on proliferation in primary endothelial cells (HUVECs), which are similar to those in tumor cell lines 9,11 , and lie in the same range as those for jasplakinolide 27 . Interestingly, MiuA inhibited migration of HUVECs in contrast to jasplakinolide, which has been previously reported to paradoxically increase migration 28,29 .…”

Neuronal Cytoskeleton in Intellectual Disability: From Systems Biology and Modeling to Therapeutic Opportunities

“…Analogously, the myxobacterial compound miuraenamide A binds to and stabilizes F-actin by competing with ADF/cofilin for its binding site [ 421 ]. Interestingly, low-dose treatment of SKOV3 and HUVECs cells with miuraenamide A showed no effects on cell viability and proliferation, while actin structure was initially subtly changed, but recovered subsequently [ 422 ].…”

Synthesis of modified miuraenamides – the Ugi approach

“…18,19 The same effects were also observed for the geodiamolides, 17 chondramides 20,21 and the miuraenamides. [22][23][24] While the other natural products contain six to seven stereogenic centres, the miuraenamides A-C contain only three asymmetric Catoms (and one stereoisomeric double bond). Therefore, the miuraenamides might be ideal candidates for the development of potential anti-tumor drugs.…”