Figure 4.

Proposed mechanisms involved in in vitro anticancer activity of surfactin. The anticancer activity of surfactin is associated with growth inhibition, cell cycle arrest, cell death (apoptosis), and metastasis inhibition. Surfactin treatment can inhibit cancer cell viability by inactivating the cell survival signaling pathways. Besides, surfactin regulates cell cycle-regulatory proteins, which are pivotal for cell cycle phase transition to block the proliferation of cancer cells. The apoptotic effect (intrinsic mitochondrial/caspase pathway) of surfactin is mediated by two different pathways that are triggered by high intracellular ROS formation, namely ERS/[Ca²⁺]_i/ERK1/2 and JNK/ΔΨm /[Ca²⁺]_i/Bax-to-Bcl-2 ratio/cyt c pathways. Surfactin-induced apoptosis is also associated with the changes in phospholipids composition that leads to a significant decrease in unsaturated degree of cellular fatty acids. Apart from these, surfactin also inhibits the invasion, migration and colony formation of cancer cells in the virtue of MMP-9 expression change that involves the inactivation of NF-κB, AP-1, PI3K/Akt, and ERK1/2 signaling pathways.