Overcoming the nutritional immunity by engineering iron scavenging bacteria for cancer therapy

Certain bacteria demonstrate the ability to target and colonize the tumor microenvironment, a characteristic that positions them as innovative carriers for delivering various therapeutic agents in cancer therapy. Nevertheless, our understanding of how bacteria adapt their physiological condition to the tumor microenvironment remains elusive. In this work, we employed liquid chromatography-tandem mass spectrometry to examine the proteome ofE. colicolonized in murine tumors. Comparing toE. colicultivated in the rich medium, we found thatE. colicolonized in tumors notably upregulated the processes related to ferric ions, including the enterobactin biosynthesis and iron homeostasis. This finding indicated that the tumor is an iron-deficient environment toE. coli. We also found that the colonization ofE. coliin the tumor led to an increased expression of lipocalin 2 (LCN2), a host’s protein that can sequester the enterobactin. We therefore engineeredE. coliin order to evade the nutritional immunity provided by LCN2. By introducing the IroA cluster, theE. colisynthesizes the glycosylated enterobactin, which creates steric hindrance to avoid the LCN2 sequestration. The IroA-E. colishowed enhanced resistance to LCN2 and significantly improved the anti-tumor activity in mice. Moreover, the mice cured by the IroA-E. colitreatment became resistant to the tumor re-challenge, indicating the establishment of immunological memory. Overall, our study underscores the crucial role of bacteria’s ability to acquire ferric ions within the tumor microenvironment for effective cancer therapy.