In vitro antitumor activity of Lactococcus lactis cell-free supernatant on human glioblastoma cell lines

In the last few years, probiotics have gained much attention within the medical, pharmaceutical, and food fields, given the health benefits provided by their consumption. They include several lactic acid bacteria (LAB) species, mostly belonging to the genera Lactobacillus, Lactococcus, and Streptococcus. Postbiotics are bioactive compounds (organic acids, short-chain fatty acids, enzymes, and neurotransmitters) produced by bacterial fermentation that exert different health effects. It is well known that probiotics, as health-promoting microorganisms, show different therapeutic properties, including anti-pathogenic, anti-inflammatory, and cholesterol-lowering activities. Recently, accumulating evidence has shown that certain commensal bacteria play protective roles against cancer; thus, anti-carcinogenic activity is one of the most interesting probiotics properties that is currently under investigation. Here, we studied the in vitro anticancer properties of postbiotics produced by three different Lactococcus lactis subsp. lactis strains isolated from natural whey starter cultures on human glioblastoma cell lines. MTT and trypan blue exclusion assays revealed a significant reduction in cell proliferation, and flow cytometry analysis corroborated this data, demonstrating a cell cycle arrest in treated cells. Moreover, other cancer hallmarks, such as wound healing rate closure and migration, were markedly inhibited by postbiotics. On the other hand, primary astrocytes viability and the blood-brain barrier (BBB) integrity were not impaired, suggesting a selective effect of postbiotics on proliferating-undifferentiated cells. This preliminary in vitro study highlights, for the first time, the potential anticancer properties of postbiotics from some L. lactis strains on human glioblastoma cell lines.