Researchers have discovered that after chemotherapy, dormant cancer cells eat neighbouring cells to relapse cancer growth. They observed this in human cancer cell lines and mice mammary tumours (1). This discovery has implications in cancer therapy as relapse is a major problem after chemotherapy in many types of cancers. The study was published in the Journal of Cell Biology (1).
Chemotherapy has been extensively used to treat various types of cancer. In chemotherapy, patients are injected with chemicals that kill cancer tissue more than normal tissue. However, after treatment, many cancers usually relapse. This recurrence of cancer after chemotherapy is common in all cancers especially breast & ovarian cancers and also glioblastoma.
Chemotherapy kills cancer cells by inducing in them a molecular pathway that causes cells to kill themselves. This process is called apoptosis. In some cancer cells however, chemotherapy does not induce apoptosis. Instead these cells undergo senescence, a dormant state where cells don’t grow or divide (2). How senescence is regulated is in itself an active field of scientific research. It is believed that these dormant cancer cells which remain after chemotherapy might be the cells responsible for relapse of tumour growth in cancers. Various mechanisms have been proposed on how these dormant cancer cells relapse after chemotherapy.
Researchers have now reported a new mechanism how cancer cells relapse. They found that chemotherapy treated dormant cancer cells bounce back to activity by engulfing and digesting nearby cancer cells (1). Researchers believe this cannibalistic act gives the cancer cells all the resources to start actively dividing again resulting in tumour relapse.
Cells eating cells is not new to us and our body. Macrophages are immune cells which eat away damaged self cells or foreign cells. This process is called phagocytosis. Cancer cell cannibalism has also been noted in the past (3). The new study validates this phenomenon and also makes a connection to tumour relapse. Now it would be interesting to see how this pathway can be exploited for new treatment strategies against cancer relapse.
- 1.C. A. Tonnessen-Murray, W. D. Frey, S. G. Rao, A. Shahbandi, N. A. Ungerleider, J. O. Olayiwola, L. B. Murray, B. T. Vinson, D. B. Chrisey, C. J. Lord, J. G. Jackson, J. Cell Biol., in press, doi:10.1083/jcb.201904051.
- 2.A. C. Yeh, S. Ramaswamy, Mechanisms of Cancer Cell Dormancy–Another Hallmark of Cancer? Cancer Research, 5014–5022 (2015).
- 3.F. Lozupone, S. Fais, Cancer Cell Cannibalism: A Primeval Option to Survive. Curr Mol Med. 15, 836–41 (2015).