Pseudozyma spp. and Barnettozyma spp. effectively kill cancer cells in vitro

Cancer is the overall leading cause of death in developed countries and also worldwide, and being able to exploit an effective anticancer drug is the aim of all cancer scientists. However, many of the synthetic drugs produced so far usually cause serious side effects, which reduces their therapeutic efficacy. Discovering new drugs or auxiliary therapies derived from natural products might thus provide a novel opportunity for cancer therapy. A recent study reported that some lethal toxins can maintain their activity after being injected into mice. We therefore used two Pseudozyma spp. and three Barnettozyma spp. to examine whether these killer yeasts can preserve their lethal effect on cancer cells under the physical environment (optimum pH, temperature and osmolality, supporting a living cell accomplishes to proliferate, metabolize, differentiate and survive). Our preliminary results showed that both Barnettozyma spp. and Pseudozyma spp. have stronger cytotoxicity against HepG2 than Chang’s liver cells. According to the results of two-dimensional difference gel electrophoresis (2D-DIGE), a total of 115 and 27 proteins differentially expressed by 1.5-fold or more were observed for HepG2 and Chang’s liver cells, respectively. Furthermore, we explored the mechanism involved in the effect of the lethal yeast filtrates on liver cancer cells using 2D-DIGE and mass spectrometry.