Cancer in the den
Cancer cells can go into "hibernation", waiting out chemotherapy
Sergey Vasiliev, Naked Science
In many cases, modern treatment allows you to completely get rid of a malignant tumor. But relapses often occur, and even after several years of interruption, metastases may reappear in the body. This is possible due to the transition of tumor cells into a state of "hibernation", which was recently discovered by scientists from the Canadian Princess Margaret Cancer Hospital.
"There are many animals that reversibly enter a state of slow metabolism in order to survive in adverse conditions. It seems that tumor cells are also capable of this for the sake of survival," he says Catherine O'Brien, who led a group of researchers. "The tumor acts like a whole organism, switching to slow division and saving energy."
In an article published in the journal Cell (Rehman et al., Colorectal Cancer Cells Enter a Diapause-like DTP State to Survive Chemotherapy), O'Brien and her colleagues write about conducting laboratory experiments with human rectal cancer cells. Such cell cultures were exposed to chemotherapy and found that the cells in them react in a coordinated manner and when the corresponding toxic substances appear, they stop actively moving and dividing, sharply reducing their oxygen and nutrition needs.
The authors called this condition a "Drug-Tolerant organism" (DTP). According to them, any tumor cell in the appropriate conditions is able to switch to this form, and when favorable conditions occur, it can return to active life again.
The process was demonstrated in experiments on mice that were surgically implanted with cancer cells, allowed to develop tumors, and then chemotherapy was performed. During eight weeks of treatment, tumor growth stopped, but continued again after its termination. Scientists took such cells again and transplanted them to the next animals. Here they also developed into a tumor, which was again able to enter the DTP state under the influence of chemotherapy drugs, and then return to normal and resume growth.
A picture from an article in Cell – VM.
The authors compared this behavior with the ability of many animals to temporarily stop the development of embryos until suitable conditions occur. Both conditions are associated with changes in the regulation of autophagy mechanisms, "controlled suicide" of old and diseased cells. Scientists have demonstrated this by successfully destroying the tumor by combining chemotherapy with autophagy inhibitors. "This is a completely new approach to the problem of resistance to chemotherapy," concludes O'Brien, "and how to overcome it."
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