Multiwalled Carbon Nanotubes Display Microtubule Biomimetic Properties in Vivo, Enhancing Microtubule Assembly and Stabilization

Abstract

Microtubules are hollow protein cylinders of 25 nm diameter which are implicated in cytokinetics and proliferation in all eukaryotic cells. Here we demonstrate in vivo how multiwalled carbon nanotubes (MWCNTs) interact with microtubules in human cancer cells (HeLa) blocking mitosis and leading to cell death by apoptosis. Our data suggest that, inside the cells, MWCNTs display microtubule biomimetic properties, assisting and enhancing noncentrosomal microtubule polymerization and stabilization. These features might be useful for developing a revolutionary generation of chemotherapeutic agents based on nanomaterials.

Exposure to Carbon Nanotubes Leads to Changes in the Cellular Biomechanics

“…Specifically, our study shows that after 24 h exposure, MWCNTs localize at the cell nucleus, with nanotube localization inducing changes in the nucleus mechanics by increasing its stiffness and overall Young's modulus with more than 36.6% than for control cells (either cells exposed to 1 h acids-washed MWCNTs for 1 h or to the control cells). Combining our data with previous reports that indicate that MWCNTs interact with microtubules, [22,46] the mitotic spindle, [22] DNA and cell division apparatus, [17,18] we propose now that the observed stiffness due to exposure to 1 h acids-washed MWCNTs could lead the reorganization of the three-dimensional cellular cytoskeletal network. Such reorganization could potentially disrupt the mitotic spindle, [22] inducing errors in chromosome numbers to be propagated through further cellular division [19] as characteristics of cancer cells.…”

“…Combining our data with previous reports that indicate that MWCNTs interact with microtubules, [22,46] the mitotic spindle, [22] DNA and cell division apparatus, [17,18] we propose now that the observed stiffness due to exposure to 1 h acids-washed MWCNTs could lead the reorganization of the three-dimensional cellular cytoskeletal network. Such reorganization could potentially disrupt the mitotic spindle, [22] inducing errors in chromosome numbers to be propagated through further cellular division [19] as characteristics of cancer cells. [48] This is also in agreement with comparative gene expression analysis that indicated that the molecular basis of the cell stiffness is reflective of the extensive molecular changes in cytoskeleton remodeling pathways [45] and with previous reports that have shown that tumorgenic and metastatic potential are linked to cellular deformability.…”

“…[18,19] For instance, our recent studies have shown that 24 to 72 h exposure of epithelial cells to SWCNTs induced centrosome fragmentation and aneuploidy [18,20] similar to the genotoxin vanadium pentoxide. [21] Likewise, cellular exposure to MWCNT disrupted the mitotic spindle by association with microtubules, [22] induced polyploidy [17] and changes in chromosome number in a fashion similar to crocidolite asbestos. [20,23,24] CNTs genotoxicity has been attributed to a variety of factors including metal impurities, length, size, number of walls, surface area, dispersion, and/or CNTs surface functionalization.…”

“…[33] Other studies have shown that MWCNTs interact with microtubules, blocking mitosis and leading to cell death by apoptosis. [22] Given the complex effects of CNTs on increased genetic instability with potential carcinogenic risks, as well as the association of CNTs with the cytoskeletal filaments, it is important that we begin to understand how exposure to these nanomaterials affects cellular biomechanics that may be functionally linked to mechanisms involved in CNTs-induced genotoxicity and potentially in cancer development.…”

Evaluating the biological risk of functionalized multiwalled carbon nanotubes and functionalized oxygen-doped multiwalled carbon nanotubes as possible toxic, carcinogenic, and embryotoxic agents

“…55 This concern cannot be dismissed because it is known that CNT-treated cells are affected during the cell cycle and tend to increase the proliferation. [55][56][57][58] We also found cell cycle alterations with shorter doubling times in fCNT-treated cells, which suggest a faster growth and consequently a greater proliferative process, instead a cell cycle blockage at followed by apoptosis, as is suggested by Rodriguez-Fernandez et al 59 These data could indicate that fCNTs would have a typical inductor factor behavior that could lead the MSCs toward a neoplastic state. In our own work, we have observed that the cells treated only with fMWCNTs can cause cell morphology alterations and probably nuclear damage, acquiring a shape that is notably similar to cells reported by Magrez et al 60 for lung cancer but rather absent in cells treated with fCOx.…”