Role of biofilm in cancer invasion.

Biofilms produced by bacteria are one of the recognized causes in cancer development and progression. These microbial communities with specific structures are embedded in extracellular matrices. They facilitate chronic infections by enhancing the resistance to various antibiotics and immune defense system of the host. An underlying key mechanism for this process is called quorum sensing (QS). It's basically a cell - density dependent signaling system that regulates bacterial behavior and biofilm formation. Different QS molecules such as N-acyl homoserine lactones have been seen to modulate immune responses and promote different processes like epithelial-mesenchymal transition (EMT), thereby contributing to tumor invasion and metastasis. Also, biofilm associated bacteria can directly reprogram host cells too. Certain bacterial toxins such as colibactin from genotoxic strains of E.coli induce DNA damage and somewhat of genetic instability, both of which are hallmarks of cancer initiation. Similarly, adhesins like FadA activate signaling cascades in host epithelial cells, which are considered as genetic expression altering molecules. Therefore, disrupting the QS pathways and targeting microbial effectors that hijack host signaling, are emerging as very promising therapeutic strategies. Further future research, aimed mainly at decoding the biofilm and its host interactions, may unlock novel treatments to cancer progression and eliminate them.