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Berberine is a natural isoquinoline alkaloid, the majority of which is extracted from Huang Lian and other medicinal herbs. Numerous studies have revealed that berberine exhibits anticancer activity, however the mechanisms underlying this effect remain elusive. To examine these mechanisms, we analyzed the effects of berberine on a panel of DNA repair deficient chicken B lymphocyte (DT40) clones. Our results revealed that DT40 cells deficient in Rev3 (Rev3-/-), a translesion DNA synthesis (TLS) gene, were hypersensitive to berberine. Following berberine treatment, cell cycle analysis identified that G2/M arrest was increased in Rev3-/- cells. Furthermore, compared with wild-type cells (WT), berberine also induced a significant increase in double-strand breaks (DSBs) in Rev3-/- cells, as revealed by chromosomal aberration (CA) analysis. These results suggest that berberine is able to induce DNA damage, and that the Rev3 associated DNA repair pathway participates in the processes that aid its repair.

Deltonin, a steroidal saponin isolated from Dioscorea zingiberensis Wright, exhibits high cytotoxic activity in cancer cells. In the present study, the effects of deltonin on cell proliferation and apoptosis were evaluated in the MDA‑MB‑231 human breast carcinoma cell line. Following treatment with deltonin, the viability of MDA‑MB‑231 cells was analyzed using MTT assay and apoptosis, mitochondrial membrane potential (∆Ψm) alternation and intracellular reactive oxygen species (ROS) generation was determined by flow cytometry. In addition, western blot analysis was performed to examine the expression of apoptosis‑associated proteins. The results demonstrated that deltonin induced apoptosis in MDA‑MB‑231 cells in a time‑ and concentration‑dependent manner. Apoptosis was associated with depolarization of ∆Ψm and time‑dependent ROS generation. Deltonin treatment also resulted in Bax upregulation, Bcl-2 downregulation, activation of caspase‑3 and ‑8 and poly (ADP ribose) polymerase cleavage. Decreased levels of phosphorylated extracellular signal‑regulated kinase (ERK) and phosphorylated AKT were also observed. Results indicate that the proliferation inhibitory effect of deltonin is associated with its apoptosis‑inducing effect, which may correlate with ROS‑mediated mitochondrial dysfunction as well as activation of the ERK/AKT signaling pathways. Therefore, deltonin may be a potential chemotherapeutic agent for the treatment of breast cancer.