Implications Of The Cancer Stem Cell For Neuro-Oncology and Neurology
Implications Of The Cancer Stem Cell For Neuro-Oncology and Neurology
The cancer stem cell hypothesis posits that cancers contain a subset of neoplastic cells that propagate and maintain tumors through sustained self-renewal and potent tumorigenecity. Recent excitement has been generated by a number of reports that have demonstrated the existence of cancer stem cells in several types of brain tumors. Brain cancer stem cells - also known as tumor-initiating cells or tumor-propagating cells - share features with normal neural stem cells but do not necessarily originate from stem cells. Although most cancers only have a small fraction of cancer stem cells, these tumor cells have been demonstrated in laboratory studies to contribute to therapeutic resistance, formation of new blood vessels to supply the tumor and tumor spread. As malignant brain tumors rank among the deadliest of all neurologic diseases, the identification of new cellular targets may have profound implications in neuro-oncology. Novel drugs that target stem cell pathways active in brain tumors have been efficacious against cancer stem cells, suggesting that anticancer stem cell therapies may advance brain tumor therapy. The cancer stem cell hypothesis may have several implications for other neurologic diseases as caution must be exercised in activating stem cell maintenance pathways in cellular therapies for neurodegenerative diseases. The ability for a small fraction of cells to determine the overall course of a disease may also inform new paradigms of disease that may translate into improved patient outcomes.
'Evil enters like a needle and spreads like an oak tree'
Ethiopian proverb
The War on Cancer was declared by President Nixon in 1971. In the intervening decades, cancer treatment has improved such that the diagnosis of cancer is not a certain death sentence, but victory remains out of grasp. In particular, patients diagnosed with malignant brain cancers continue to suffer high morbidity and mortality. Multiple scientific advances - radiotherapy modalities, gene therapy, the Human Genome Project and targeted molecular drugs - have been hailed as signs of a coming revolution in brain cancer care only to disappoint when the benefits of each have proven more modest. Now, excitement is building around the cancer stem cell field. Viewing cancer through the prism of the cancer stem cell hypothesis may fundamentally transform brain cancer biology and translate into improved diagnosis, prognosis and treatment of brain tumor patients, but the reality is likely complex and challenging. The brain cancer stem cell field is immature - we are only beginning to recognize the rules governing cancer stem cell biology - but common themes are emerging in studies of cancer stem cells derived from a diversity of tumor types, suggesting that core mechanisms may underlie tumor formation and maintenance. However, controversies surround cancer stem cells, with some researchers disputing the existence of cancer stem cells. Cancer stem cell biology has recently been reviewed in several publications so I will focus this review on the potential for, and challenges of, cancer stem cells.
The cancer stem cell hypothesis posits that cancers contain a subset of neoplastic cells that propagate and maintain tumors through sustained self-renewal and potent tumorigenecity. Recent excitement has been generated by a number of reports that have demonstrated the existence of cancer stem cells in several types of brain tumors. Brain cancer stem cells - also known as tumor-initiating cells or tumor-propagating cells - share features with normal neural stem cells but do not necessarily originate from stem cells. Although most cancers only have a small fraction of cancer stem cells, these tumor cells have been demonstrated in laboratory studies to contribute to therapeutic resistance, formation of new blood vessels to supply the tumor and tumor spread. As malignant brain tumors rank among the deadliest of all neurologic diseases, the identification of new cellular targets may have profound implications in neuro-oncology. Novel drugs that target stem cell pathways active in brain tumors have been efficacious against cancer stem cells, suggesting that anticancer stem cell therapies may advance brain tumor therapy. The cancer stem cell hypothesis may have several implications for other neurologic diseases as caution must be exercised in activating stem cell maintenance pathways in cellular therapies for neurodegenerative diseases. The ability for a small fraction of cells to determine the overall course of a disease may also inform new paradigms of disease that may translate into improved patient outcomes.
'Evil enters like a needle and spreads like an oak tree'
Ethiopian proverb
The War on Cancer was declared by President Nixon in 1971. In the intervening decades, cancer treatment has improved such that the diagnosis of cancer is not a certain death sentence, but victory remains out of grasp. In particular, patients diagnosed with malignant brain cancers continue to suffer high morbidity and mortality. Multiple scientific advances - radiotherapy modalities, gene therapy, the Human Genome Project and targeted molecular drugs - have been hailed as signs of a coming revolution in brain cancer care only to disappoint when the benefits of each have proven more modest. Now, excitement is building around the cancer stem cell field. Viewing cancer through the prism of the cancer stem cell hypothesis may fundamentally transform brain cancer biology and translate into improved diagnosis, prognosis and treatment of brain tumor patients, but the reality is likely complex and challenging. The brain cancer stem cell field is immature - we are only beginning to recognize the rules governing cancer stem cell biology - but common themes are emerging in studies of cancer stem cells derived from a diversity of tumor types, suggesting that core mechanisms may underlie tumor formation and maintenance. However, controversies surround cancer stem cells, with some researchers disputing the existence of cancer stem cells. Cancer stem cell biology has recently been reviewed in several publications so I will focus this review on the potential for, and challenges of, cancer stem cells.