Bacterial protein MakA causes suppression of tumour cell proliferation via inhibition of PIP5K1α/Akt signalling

Metallo-protease Peptidase M84 from Bacillusaltitudinis induces ROS-dependent apoptosis in ovarian cancer cells by targeting PAR-1

We have purified Peptidase M84 from Bacillus altitudinis in an effort to isolate anticancer proteases from environmental microbial isolates. This metallo-protease had no discernible impact on normal cell survival, but it specifically induced apoptosis in ovarian cancer cells. PAR-1, a GPCR which is reported to be overexpressed in ovarian cancer cells, was identified as a target of Peptidase M84. We observed that Peptidase M84 induced PAR-1 overexpression along with activating its downstream signaling effectors NF-κB and MAPK to promote excessive reactive oxygen species (ROS) generation. This evoked apoptotic death of the ovarian cancer cells through the intrinsic route. In in vivo set-up, weekly intraperitoneal administration of Peptidase M84 in syngeneic mice significantly diminished ascites accumulation, increasing murine survival rates by 60%. Collectively, our findings suggested that Peptidase M84 triggered PAR-1-mediated oxidative stress to act as an apoptosis inducer. This established Peptidase M84 as a drug candidate for receptor mediated targeted-therapy of ovarian cancer.

Host-derived oxidized phospholipids initiate effector-triggered immunity fostering lethality upon microbial encounter

Macrophages detect invading microorganisms via pattern recognition receptors that recognize pathogen-associated molecular patterns, or via sensing the activity of virulence factors that initiates effector-triggered immunity (ETI). Tissue damage that follows pathogen encounter leads to the release of host-derived factors that participate to inflammation. How these self-derived molecules are sensed by macrophages and their impact on immunity remain poorly understood. Here we demonstrate that, in mice and humans, host-derived oxidized phospholipids (oxPLs) are formed upon microbial encounter. oxPL blockade restricts inflammation and prevents the death of the host, without affecting pathogen burden. Mechanistically, oxPLs bind and inhibit AKT, a master regulator of immunity and metabolism. AKT inhibition potentiates the methionine cycle, and epigenetically dampens Il10, a pluripotent anti-inflammatory cytokine. Overall, we found that host-derived inflammatory cues act as "self" virulence factors that initiate ETI and that their activity can be targeted to protect the host against excessive inflammation upon microbial encounter.