✔ ✔ ✔ CHECKPOINTS: STOP OR GO? MITOSIS & Cytokinesis • DNA checked, repaired • enough organelles? MITOSIS & Cytokinesis ✔ • spindle attached? ✔ duplicate organelles G0 growth INTERPHASE INTERPHASE Protein regulators are molecular signals that may stimulate or halt division, instruct cells to differentiate, or trigger cell death. Errors in the sinaling process can cause too few (hair loss) or too many (tumor) cells. ✔ • SA:V ratio? • more cells needed? • adequate room? replication Cells Alive Biointeractive tutorial

REGULATING THE CHECKPOINTS: • proto-oncogenes trigger cell division, direct cell to continue in the cycle turn on the gas! • tumor-suppressor genes shut down the cycle hit the brakes! Protein regulators are molecular signals that may stimulate or halt division, instruct cells to differentiate, or trigger cell death. Errors in the sginaling process can cause too few (hair loss) or too many (tumor) cells. . A consequence of an uncontrolled cell cycle is that the tissue formed from cell division is often non-functional. Without control the growth does not take on the proper form or interact normally with other cell types. The root cause of the growth is a gene

EFFECTS OF MUTATIONS In proto-oncogenes > • less division therefore too few cells • more division, creating too many cells, increasing likelihood of mutation In tumor-suppressor genes > • loss of inhibition too many cells creates TUMORS Protein regulators are molecular signals that may stimulate or halt division, instruct cells to differentiate, or trigger cell death. Errors in the sginaling process can cause too few (hair loss) or too many (tumor) cells. . A consequence of an uncontrolled cell cycle is that the tissue formed from cell division is often non-functional. Without control the growth does not take on the proper form or interact normally with other cell types. The root cause of the growth is a gene Animation 1

More division increases likelihood of more mutations What else causes mutations?

Cells stop dividing when they should National Cancer Institute Understanding Cancer and Related Topics Understanding Cancer normal cells Cells stop dividing when they should Cells die when damaged mutation > cell death cancer cells Abnormal growth Abnormal DNA Cancer arises from a loss of normal growth control. In normal tissues, the rates of new cell growth and old cell death are kept in balance. In cancer, this balance is disrupted. This disruption can result from uncontrolled cell growth or loss of a cell’s ability to undergo cell suicide by a process called“apoptosis.” Apoptosis, or “cell suicide,” is the mechanism by which old or damaged cells normally self-destruct. NCI Web site: http://cancer.gov/cancertopics/understandingcancer

TUMOR DIRECTS MORE GROWTH National Cancer Institute Understanding Cancer and Related Topics Understanding Angiogenesis TUMOR DIRECTS MORE GROWTH Tumor that can grow and spread tumor angiogenesis signals blood vessel Signal molecules Tumor angiogenesis is the proliferation of a network of blood vessels that penetrates into cancerous growths, supplying nutrients and oxygen and removing waste products. Tumor angiogenesis actually starts with cancerous tumor cells releasing molecules that send signals to surrounding normal host tissue. This signaling activates certain genes in the host tissue that, in turn, make proteins to encourage growth of new blood vessels. cell releases signal molecules that cause blood vessels to grow blood vessels bring in nutrients and removes waste products NCI Web site: http://cancer.gov/cancertopics/understandingcancer

CANCER SPREADS via blood vessels National Cancer Institute Understanding Cancer and Related Topics Understanding Angiogenesis CANCER SPREADS via blood vessels tumor breaches organ wall 1. Cancer cells invade surrounding tissues and vessels Blood vessel cells lodge, grow in other organs When patients are diagnosed with cancer, they want to know whether their disease is local or has spread to other locations. Cancer spreads by metastasis, the ability of cancer cells to penetrate into lymphatic and blood vessels, circulate through the bloodstream, and then invade and grow in normal tissues elsewhere. In large measure, it is this ability to spread to other tissues and organs that makes cancer a potentially life-threatening disease, so there is great interest in understanding what makes metastasis possible for a cancerous tumor. Metastasis blood transports cancer cells NCI Web site: http://cancer.gov/cancertopics/understandingcancer

DIFFERENT TYPES OF CANCERS DIFFERENT TYPES OF TREATMENTS Radiation – use EM waves to disrupt tumor cell DNA Chemotherapy - toxic chemical cocktail problem: both therapies kill mitotic cells, cancerous AND healthy Disrupt signal molecules produced by tumor cells Block growth of blood vessels to tumors Use immune system to attack cancer like it does a virus Vaccines for microbe-caused cancers (HPV)