Sometimes one of the most important things about research is the questions it provokes. In this case, the question “Why do some cancers resist treatment?” comes out of research that has found a plausible answer. The work involved a standing question in stem cell research – How does the body regulate the two different kinds of stem cells, one for ongoing cell reproduction and maintenance and the other for tissue repair in case of emergencies?

Dr. Linheng Li, University of Kansas (USA) and Linheng Li Labs, Inc. along with Dr. Hans Clevers, Director of the Hubrecht Institute in Utrecht, Netherlands built upon early work at Linheng Li Labs that established two type of adult stem cells: Active (the ones involved in cell maintenance) and quiescent (cells held in reserve in case of need for replacement stem cells or tissue repair in an emergency). Their new study indicates that the two types of stem cells exist in the same tissue but in two different ‘zones,’ in a sense two different microenvironments, one that keeps the active cells primed and ready for use, the other keeping quiescent cells dormant but ready for activation in emergency such as tissue injury.

This ‘two zone’ theory provides the structural explanation for what must be a molecular process that maintains the two stem cell populations and keeps them in relative balance. The research also opened the door to ask questions about the role of stem cells in cancer. As they explained:

Intriguingly, cancers may utilize this same mechanism to maintain co-existing active-quiescent pools of stem cell sub-populations that support fast tumor growth (by active stem cells) while preserving the root of malignancy (by quiescent stem cells). This may explain the basis of drug resistance to cancer treatment.

“If this hypothesis is true, the critical question will be how to target quiescent drug-resistant cancer stem cells,” said Dr. Li. “We will test this model in cancers in an effort to determine how to activate quiescent (drug-resistant) cancer stem cells for further targeting.”

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If this research proves out, it is not only a useful insight into how adult stem cells are used in the body, but also a potential new area for exploration in the realm of cancer treatment.