Genetic changes altering growth regulatory functions of cells leading to de

• Genetic changes altering growth regulatory functions of cells leading to de-differentiation • Most of these changes/mutations happen in cells during their symmetric linear phase of growth

Embryonal rest/De-differentiation

Identifying Cancer Stem Cells Scientists can break up the cells of a tumor, then transplant each tumor cell into a new location…. Most of the tumor cells end up dying… But a rare few go on to grow a new tumor… Cancer Stem Cells Tumor

Cancer Stem Cells (CSCs) "It's like dandelions in the back yard: You can cut the leaves off all you want, but unless you kill the root, it will keep growing back.“ Cells with stem-like behaviors have been found in the following cancers and others as well: Breast Cancer; Colon Cancer; Leukemia; Prostate Cancer; Melanoma; Pancreatic Cancer & Some Malignant Brain Tumors Implications for therapy Cure of cancer may require elimination of the minority cancer stem cell population of the tumor as well as the non-CSC majority of cancer cells. The possibility that different therapies may be needed to eliminate cancer stem cells complicates the search for definitive cures. For example, some CSCs appear to be more resistant to radiation than other cells of the tumor * * John Dick, leader of the team that discovered colon and leukemia CSCs

Chemotherapy: Targets Rapidly Dividing Cells Conventional chemotherapy targets rapidly dividing cells. Stem cells do not divide rapidly, so are not targeted by chemotherapy. X X X

Chemotherapy: Targets Rapidly Dividing Cells The stem cell survives conventional chemotherapy and divides to form a new tumor Cancer Stem Cell Tumor treated with chemotherapy

What’s coming in cancer therapy? New targeted drugs that specifically kill cancer stem cells without harming normal stem cells should remove the “root” of the cancer. The rest of the cancer cells should die on their own, or conventional chemotherapy drugs can be used to kill these cells

Targeting Cancer Stem Cells Therapeutically depriving microenvironment signals to cancer stem cells

Scientists are searching for answers to these questions about cancer stem cells… What makes these cells different? What kinds of drugs can target these cells? What cellular pathways are affected by drugs that target these cells? Are there other possible drugs that target those pathways?