increasing incidence of leukemia; non-Hodgkin lymphoma
The global community is plagued by increasing incidence of leukemia; non-Hodgkin lymphoma; lung, colorectal, breast, pancreatic, prostate, liver, ovarian, and esophageal cancers. Other types of cancer exist but are less frequent. What is the scientific community doing to attempt to eliminate the most common forms of cancer that are ravaging society?
1. Read the course textbook’s chapter on cell division, specifically the last section on how cells become cancerous. This is context for completing Individual Assignment 3.
2. Watch the Presentation in Module/Week 4 entitled “Ways to Fight Cancer.” Notice that the presentation outlines essentially 3 approaches to fighting cancer: a) reduction of cancer risks, b) correction of cancer genes, and c) destruction of cancerous tissue.
3. Open the “10 Discoveries in the War on Cancer” document in the Assignment Instructions folder. Scan the discoveries briefly. Then, open the assignment submission link in Module/Week 9. In the text box, number from 1 to 10 for the 10 discoveries.
4. Reflect carefully on discovery 1. Would this discovery be more useful for a) reducing cancer risks, b) correcting/restoring cancer cells to normal, or c) destroying cancerous tissue? After number 1 in your list, place in parentheses the letter representing the approach to fighting cancer that will best be served by this new discovery. (More than 1 approach may be served, but which is most likely to be helped most significantly?)
5. Repeat this analysis for each of the remaining 9 discoveries. Return to the “Ways to Fight Cancer” presentation as needed for additional perspective. When finished, your entire text box must be simple: a numbered (1–10) list of letters (a), (b) or (c). The assignment is now complete.
6. Each correct association up to 8 correct answers is granted 7 points. If you get 9 or 10 out of 10, you get a perfect score (60 pts.) on the assignment.
Submit this assignment by 11:59 p.m. (ET) on Monday of Module/Week 4.
Individual Assignment 3 – 10 Discoveries in the War on Cancer
1. Virologists are modifying lentiviruses as vectors for carrying proto-oncogenes into cancer-transformed cells in culture. They are developing this virus for inserting the ras proto-oncogene directly into its correct location in the genome. The correct ras gene will already be linked to human DNA on either side of it and complexed with a recombination enzyme that will insert it into its correct location within the human genome. At the same time, the recombination enzyme will excise the defective oncogenic form of ras. The cells in culture should again come under normal hormonal control and require extra-cellular signals in order to continue dividing.
2. Malignant brain tumors in adults are fast-growing cancers with median survival rates of 15 months, even with aggressive treatment. Researchers have been searching for genetic “signatures” (characteristic groups of cancer-causing genes) that could help in defining the kind of brain tumor the patient has. They hope to be better able to predict the course of the disease and more accurately design the patient’s course of treatment.
3. Tobacco smoking is the leading cause of preventable deaths worldwide. It is a risk factor for lung cancer and several other types of cancer. Results of analysis of the entire human gene collection (the “genome”) support some previous findings that a region of human chromosome number 15 contains one or more genes that are associated with smoking intensity (the number of cigarettes smoked per day) and the closely related trait of nicotine dependency. Scanning people’s genomes for these genes will help them to determine their risk of addiction should they begin smoking tobacco.
4. Immunologists are working with a mutation (HER2) that is expressed on the surface of many breast, bladder, pancreatic, and ovarian cancer cells. They have made antibodies against this mutant surface protein. These antibodies have been covalently bonded to a “gene expression vector” that makes cells light up when incubated with luciferin from fire flies. The vector takes the gene for luciferin into the cancer cells. The researchers have shown that their antibody can accurately find and “light up” cancer cells. Their next step is to bond the antibody to an expression vector that carries the normal HER2 gene into mutant cancer cells.
5. Immunologists are investigating ways to destroy lymphocytes (white blood cells of the immune system) that have become cancerous (lymphomas). A current drug Rituximab contains antibodies that bind to the surfaces of these lymphocytes setting them up for destruction by the cancer patient’s own immune system. They are currently seeking ways to modify the antibody’s structure so that it will attract the cancer patient’s “natural killer” (NK) cells to the lymphocytes. Success of this project will bring a multi-faceted immune response against lymphomas and hasten destruction.
6. Biochemists have discovered a protein kinase enzyme named BRAF that is an important link in a molecular pathway that causes a cell to divide. Normally, BRAF responds to signals coming from outside the cell—signals calling for the cell to divide normally under normal conditions. But there is a mutation in BRAF enzymes that causes it activate the cell toward division continually. In this way it gives rise to melanomas and thyroid or ovarian cancers. Biochemists have also found a drug, vemurafenib, which binds selectively to mutant BRAF totally inactivating it. Cells that have inactivated BRAF undergo apoptosis—a process that leads to cell death.
7. Molecular biologists have taken nanoparticle-sized spheres and used them to deliver a cell-killing toxin from bee venom to tumors in mice, substantially reducing tumor growth without harming normal body tissues. Nanoparticles are known to concentrate in solid tumors because blood vessels in tumors show “enhanced permeability and retention effect” or EPR. Hence substances such as nanoparticles escape more readily from the bloodstream into tumors and the generally poor drainage of lymph from tumors further helps trap the particles in tumor tissue.
8. Organic chemists are exploring structural variations of the organic compound avobenzone (1-[4-Methoxyphenyl]-3-[4-tert-butylphenyl] propane-1,3-dione) for inclusion in sunblock products. Avobenzone is known for its ability to absorb a broad spectrum of ultra-violet radiations including UVB light (known to enhance the frequency of basal cell and squamous cell carcinomas [skin cancers]); and UVA rays thought to increase the frequency of melanoma cancers. New variations in the structure of avobenzone are hoped to retain the ability to absorb harmful UV radiation while having an increased stability in the presence of that radiation.
9. Biochemists are analyzing the many, many components of red meat (beef and pork) to determine which component, if any, will cause increased colorectal cancer rates in mice when the component is administered orally. Studies have shown that higher colorectal cancer rates in humans are associated with higher consumption rates of red meat.
10. Molecular biologists have developed a new sequence of human genes called an ankyrin insulator sequence. A new corrected or therapeutic gene is placed within this sequence. Its role is to create an active area on a human chromosome where the new gene can work efficiently no matter what chromosome it lands on.