Stem cells are unspecialized cells that differentiate in response to certain signals. Researchers have long understood that cancerous cells are in some ways similar to stem cells. Now scientists are investigating whether a stem cell protein can be used to kill breast cancer cells.
Stem Cells and Breast Cancer
Stem cells follow a one-way path during differentiation where they transform into a specific type of tissue and eventually die. Stem cells in the breast can differentiate into milk-producing luminal cells, for example, with a short lifespan. Unlike stem cells, cancer cells cannot differentiate into a specific cell type, but during development, they too follow a one-way path, albeit in the opposite direction where they begin to undergo uncontrolled multiplication.
Stem Cell Protein for Breast Cancer Treatment
At the Cold Spring Harbor Laboratory, Assistant Professor Camila dos Santos is investigating breast stem cells in the hope of identifying the changes are triggered when healthy breast cells turn cancerous. A team of scientists including Assistant Professor William Pomerantz of the University of Minnesota and Professor Gregory Hannon of the Cambridge Institute in the United Kingdom has collaborated with dos Santos and identified a protein called BPTF that is essential for the normal functioning of mammary cells.
When the team chemically inhibited or genetically removed the BPTF protein from stem cells, they could no longer renew themselves and quickly specialized into mammary cells that died soon after. This was an exciting finding because scientists are trying to figure out ways for breast cancer cells to do exactly this. In other words, the idea is to take away the stem-cell-like self-renewing qualities of breast cancer cells including the ability to indefinitely replicate. The team is now trying to develop a drug that prevents BPTF activity with the hope that it will have the same effect on breast cancer cells as it does in stem cells, causing them to mature into a specific tissue type and die.
Pathogenesis of Breast Cancer
The transformation of healthy breast cells into cancerous cells has been studied through gene expression. The complete human genome is present in every cell in the body, including stem cells. A breast cell is different from a liver cell because the two types of cells express different gene subsets.
Over the lifespan of a person, different genes are expressed in different types of cells. For example, the milk ducts in the breast are made up of two highly specialized types of cells that arise from a niche population of stem cells. Luminal cells form the lining of the hollow milk ducts and are the milk factories of the breast. A layer of myoepithelial cells surrounds the luminal cells and interacts with oxytocin hormone to squeeze out milk from luminal cells during lactation.
Genetic Role of Stem Cell Protein BPTF
BPTF has a specialized function of opening up chromatin in mammary stem cells. The opening of chromatin has been found to be critical in the ability to stem cells to replicate indefinitely into daughter cells. The opening up of chromatin also drives cancer progression. Therefore, the protein participates in a regulatory mechanism that plays a critical role in cancer progression. By developing drugs that inhibit BPTF, the investigators hope to stop the progression of mammary cancer.