Posted on by Dr. Francis Collins
Tumors rely on a variety of tricks to grow, spread, and resist our best attempts to destroy them. Now comes word of yet another of cancer’s surprising stunts: when chemotherapy treatment hits hard, some cancer cells survive by cannibalizing other cancer cells.
Researchers recently caught this ghoulish behavior on video. In what, during this Halloween season, might look a little bit like The Blob, you can see a down-for-the-count breast cancer cell (green), treated earlier with the chemotherapy drug doxorubicin, gobbling up a neighboring cancer cell (red). The surviving cell delivers its meal to internal compartments called lysosomes, which digest it in a last-ditch effort to get some nourishment and keep going despite what should have been a lethal dose of a cancer drug.
Crystal Tonnessen-Murray, a postdoctoral researcher in the lab of James Jackson, Tulane University School of Medicine, New Orleans, captured these dramatic interactions using time-lapse and confocal microscopy. When Tonnessen-Murray saw the action, she almost couldn’t believe her eyes. Tumor cells eating tumor cells wasn’t something that she’d learned about in school.
As the NIH-funded team described in the Journal of Cell Biology, these chemotherapy-treated breast cancer cells were not only cannibalizing their neighbors, they were doing it with remarkable frequency . But why?
A possible explanation is that some cancer cells resist chemotherapy by going dormant and not dividing. The new study suggests that while in this dormant state, cannibalism is one way that tumor cells can keep going.
The study also found that these acts of cancer cell cannibalism depend on genetic programs closely resembling those of immune cells called macrophages. These scavenging cells perform their important protective roles by gobbling up invading bacteria, viruses, and other infectious microbes. Drug-resistant breast cancer cells have apparently co-opted similar programs in response to chemotherapy but, in this case, to eat their own neighbors.
Tonnessen-Murray’s team confirmed that cannibalizing cancer cells have a survival advantage. The findings suggest that treatments designed to block the cells’ cannibalistic tendencies might hold promise as a new way to treat otherwise hard-to-treat cancers. That’s a possibility the researchers are now exploring, although they report that stopping the cells from this dramatic survival act remains difficult.
 Chemotherapy-induced senescent cancer cells engulf other cells to enhance their survival. Tonnessen-Murray CA, Frey WD, Rao SG, Shahbandi A, Ungerleider NA, Olayiwola JO, Murray LB, Vinson BT, Chrisey DB, Lord CJ, Jackson JG. J Cell Biol. 2019 Sep 17.
Breast Cancer (National Cancer Institute/NIH)
James Jackson (Tulane University School of Medicine, New Orleans)
NIH Support: National Institute of General Medical Sciences
Posted on by Dr. Francis Collins
Live long enough, and there’s a good chance that you will develop a cataract, a clouding of the eye’s lens that impairs vision. Currently, U.S. eye surgeons perform about 3 million operations a year to swap out those clouded lenses with clear, artificial ones . But wouldn’t it be great if we could develop non-surgical ways of preventing, slowing, or even reversing the growth of cataracts? This image, from the lab of NIH-grantee Salil Lachke at the University of Delaware, Newark, is part of an effort to do just that.
Here you can see the process of lens development at work in a tissue cross-section from an adult mouse. In mice, as in people, a single layer of stem-like epithelial cells (far left, blue/green) gives rise to specialized lens cells (middle, blue/green) throughout life. The new cells initially resemble their progenitor cells, displaying nuclei (blue) and the cytoskeletal protein actin (green). But soon these cells will produce vast amounts of water-soluble proteins, called crystallins, to enhance their transparency, while gradually degrading their nuclei to eliminate light-scattering bulk. What remains are fully differentiated, enucleated, non-replicating lens fiber cells (right, green), which refract light onto the retina at the back of the eye.