Bacteria and cancer cells are talking to each other
SICOT Young Surgeons Committee Chairman - Istanbul, Turkey
Social interaction and collective behaviour are basic instincts in organisms surviving at all levels of the life cycle. Living as a group allows individuals to survive more strongly under harsh conditions than individuals who act alone. This general principle of biology is becoming more apparent for us as our knowledge about the Microcosmos has increased in the last decade.
Beyond living in close proximity to one another, bacteria release molecules to communicate with other members of the group. Bacteria sense those molecules and receive it as a signal. They process the signal concentration to estimate the microbial population density around themselves, and when the signal concentration reaches at or above a threshold level they alter their gene expression profiles. Some 'silent' genes start to get transcribed and their behaviour changes on a community-wide scale, namely they sense that they are enough in number to attack. This communication process by signaling molecules among bacteria is called 'quorum sensing'. The quorum sensing process does not necessarily activate only the virulant genes, as seen in the mutualistic relationship of vibrio and deep sea angler fish.
Numerous studies are demonstrating the immunological parallelism between infection and cancer. Some recent studies suggest a similarity in behaviour of societies of bacterial cells and societies of malignant cancer cells. The process of metastasis is actually shown to be regulated by distinct molecular phenomena. In this context, some recent studies demonstrated the cross-communication of bacteria and cancer cells over some common quorum sensing molecules. Therefore, the hypothesis that addresses the quorum sensing mechanism in cancer cells to regulate their group-level properties and behaviours in metastatic colonization is leading scientists to a link between bacteria and metastasis.
The role of quorum sensing molecules and their guiding characteristics for metastasis is such a stunning dimension of research and the explorations in this field may provide different approaches not only for cancer but also for infection. Although defining the pathways of behaviour and communication of cell groups presents a great challenge, this concept exposes an exciting direction for future research. The translation of the current progress into clinical practice will take time. However, as we further explore the common molecules, receptors and pathways of cancer and infection, we will be much more powerful against this hostile cooperation.
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