4.3. Mode of action
Vinca alkaloids bind to tubulin and cause polymerization, which inhibits microtubule assembly leading to the disruption in the mitotic spindle eventually metaphase-arrested (Fig. 9 ). Mode of action of most of the alkaloid derivatives is similar to taxanes by stimulation of apoptotic cascades and reduction of Bcl-2/Bax protein and mRNA levels, which leads to cell cycle arrest in cancer cells. In SW1116 human colon cancer cells, alkaloids derivatives downregulate human telomerase reverse transcriptase (hTERT) and upregulate p53 as well as mad1 in a concentration-dependent manner and cause cytotoxicity (Barrales-CureƱo et al., 2019).