Prometastatic Potential of Non-Functionalized Multiwalled Carbon Nanotubes in the MDA-MB-436 Breast Cancer Cell Line Model

Multiwalled carbon nanotubes (MWCNTs) are used in many areas of industry and medicine. However, there is evidence suggesting profibrogenic action of MWCNTs, probably via the epithelial-mesenchymal transition mechanism (EMT). The aim of this study was to evaluate the prometastatic activity of 5-20 nm and 50-80 nm MWCNTs against cells of the MDA-MB-436 line. We used MTT and NR assays to determine MWCNTs' cytotoxicity and the level of malonylodialdehyde and thiol compounds as indicators of oxidative stress. qRT-PCR was used to examine the expression of EMT markers. The QCM Chemotaxis Cell Migration Assay was used to assess cell migration, while the Cytokine Array Kit and Apoptosis Array Kit were used to determine cytokine expression and induction of apoptosis. The interleukin 6, C-X-C motif chemokine ligand 8, and tumor growth factor beta 1 (TGFB1) secretion was determined by ELISA. MWCNTs were toxic to MDA-MB-436 cells and induced cell death via the apoptosis pathway. MWCNTs induced a low level of oxidative stress and were associated with increased secretion of pro-inflammatory cytokines and chemokines, including proteins important in breast cancer metastasis. Cells incubated with MWCNTs showed increased expression of mesenchymal EMT markers. However, in contrast to these results, the migration of MWCNT-treated cells increased only modestly relative to untreated cells. Also, the secretion of TGFB1, a key inducer and regulator of EMT, increased only slightly. In summary, the multifaceted effect of MWCNTs on cancer cells encourages further work on the safety of nanomaterials.