MadSci Network: Cell Biology |
Hi Whitee, I study cultured breast cancer cells, which means that I grow cancer cells in flasks rather than study tumors in animals. Some of my cancer cells do not look much different from normal cells, structurally. Others are irregularly shaped. Often cancer cells have increased numbers of chromosomes, which would account for the larger and darker nuclei you mentioned in your comments. Morphological analysis can be used to detect cancerous cells in certain areas of the body. For instance, when women have Pap smears, cells from the cervix are scraped off and analyzed under the microscope. Cells with large nuclei and irregular shapes are considered abnormal. For some pictures of normal cells and cancer cells, check out http://pathology2 .jhu.edu/cyto_tutorial/Atlas/Index.cfm You can choose slides and read the captions indicating why the cell was considered normal or cancerous. There are also molecular markers that indicate whether a cell is cancerous. Checking for a variety of proteins or genes expressed in cancer cells is another method of detection. Normal cells may express these genes, but often they are modified in cancerous cells. I am not sure what you mean by "drown out normal cells" but maybe you mean that the cancer cells divide rapidly, forming tumors that can grow out of control and in a sense take over the body. When cells acquire the ability to migrate, they are malignant. Malignant cancer leads to tumors throughout the body (metastasis). When normal cells are put into a flask, they typically stop growing when they cover the bottom of the flask. This is called contact inhibitionÑthe cells stop growing when they come into contact with one another. But the cancer cells will not stop growing, indicating a loss of contact inhibition. A malignant tumor can have similar characteristics. Malignant cancer cells tend to proliferate rapidly, so interphase would not last as long as a normal cell that does not undergo mitosis as frequently. Many chemotherapy drugs target rapidly proliferating cells in hopes of eliminating cancer cells and not normal cells. Unfortunately, certain normal cells in the body proliferate rapidly and are affected by the chemotherapy drugs. This is why people with cancer who are undergoing chemotherapy can lose their hair. Trying to detect rapidly dividing cells in a human would be difficult in the early stages of cancer. You are right that there might be ways to target cancer cells, though. For example, there are drugs that are meant to starve tumors of oxygen and nutrients by cutting of their ability to promote the growth of blood vessels around them. Blood vessel growth is called angiogenesis. Blood transports oxygen and nutrients, which a tumor needs just like other cells. If the tumor cannot promote angiogenesis, it will not have blood vessels delivery oxygen and nutrients and would theoretically be starved. A drug called Herceptin is regularly used to treat cancers that over-express a particular receptor on their surface. For more information about cancer therapy, check out the National Cancer Institute website at http://www.nci.nih.gov/. So although cancer cells might look just like normal cells, there are differences that can be exploited when trying to detect and treat cancer. Please write back if you have any questions. I hope this helps! Sarah Earley
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