Combretastatin A4 (CA4) is a known anticancer drug that disrupts microtubules resulting in cell death.We aimed at enhancing the pharmacological properties of CA4 via employing a novel nanotechnology approach. The technique consists of single walled carbon nanotubes (SWCNTs) covalently functionalized with multiple copies of CA4 molecules (CNT-CA4) by cleavable ester bonds and a human cervical cancer cell line (HeLa) was utilized as a model. The prepared CNT-CA4 was characterized by different analytical techniques, including thermogravometric analysis (TGA), nuclear magnetic resonance (NMR), ultraviolet-visible (UV-Vis), scanning electron microscope (SEM) and transmission electron microscope (TEM) that confirm the successful functionalization of the SWCNTs. The CNT-CA4 anti-cancer effects were performed on HeLa cells and both proliferations as well as the cell cycle were tested by the MTS and flow cytometry, respectively.
MTS test demonstrated an anti-proliferative activity of CNT-CA4 and was comparable to that of the free CA4 (50-60% inhibition). Moreover, the flow cytometric analysis of the cell cycle using the PI staining showed a G2/M arrest in both the CNT-CA4 and CA4 agents. However, there were a superiority in the effects of the CNT-CA4 on decreasing the apoptosis rate of the Hela cells while shifting them to necrosis via the Annexin V/PI test. These elevations in necrotic/dead cells reached to 50% as compared to the free CA4. These data suggest both inhibitions in DNA synthesis as well as increase in the cytotoxicity effects of the novel CNT-CA4 indicating an anti-cancer activity.
Our results may indicate a greater entry of the novel drug by the nano-delivery system and the subsequent sustained release profile of the active drug within the cytoplasm over an extended time period and suggest anti-cancer role activity on HeLa cells.