Three independent studies have confirmed that cancer stem cells may be responsible for the development and recurrence of cancer. This is reported in the latest issue of the magazines Nature and Science.
This hypothesis has been under consideration for several years. It was suspected that there was a small group of cancer stem cells (CSC) in the tumor that could resist the treatment, even if the tumor could be reduced in size by various methods. From these cells, after some time in many patients the neoplasm grows again and the disease comes back.
So far, however, there has been no evidence of this. Only three groups of researchers have shown for the first time that this is the mechanism of neoplastic disease development in the case of brain tumors, adenomas and skin cancer. “We have proved what many specialists doubted” – said one of the authors of the research, Prof. Luis Parada from the University of Texas.
An American scientist has identified cancer stem cells in mouse glioblastoma, the most common malignant tumor of the brain. Prof. Cedric Blanpain of the Free University of Brussels found them in squamous cell carcinoma of the skin that originated in epidermal cells. In turn, Dutch researchers from the University of Utrecht found them in an adenoma, a tumor of the gastrointestinal tract, such as the large intestine. His research has the added value of finding Lgr5 mutations in them.
All these studies show that cancer stem cells are similar to healthy stem cells that regenerate tissues and organs throughout the body. The only difference is that they do not stop dividing, which is characteristic of cancer cells. They can also stay dormant for a long time to let them know even after a long time.
If at least one such cell survives the therapy and remains in the body, it can cause the cancer to come back. It is assumed that this may be the case for blood cancers such as chronic myeloid leukemia, acute lymphocytic leukemia and multiple myeloma, as well as for solid tumors such as breast, colorectal, ovarian, prostate, lung, pancreatic and liver cancer, and melanoma and malignant tumor of the brain.
Stem cells show remarkable vitality and the ability to renew themselves. To initiate a new cell, they divide into two descendants, only one of which differentiates (otherwise a new cell could not be created), and the other retains the role of the parent. Thanks to this, there is always the same number of them, at any time they are ready to create new generations of the appropriate type of differentiated cells, depending on the organism’s needs. However, these properties make them ideal for the formation of malignant cells when errors occur during their division.
Researchers speculate that cancer treatments should primarily target the eradication of these abnormal stem cells. In practice, however, this may turn out to be much more difficult than in theory. This has been the case many times in the history of the struggle with cancer. When radiation was invented, in the early XNUMXs, radiation therapy seemed to be the panacea for cancer. Today, it is only one of the three primary treatments, in addition to surgery and chemotherapy.
Zbigniew Wojtasiński (PAP)
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