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Biology Unit 5 – , Background Paper 5-12

The Hallmarks of Cancer Remember (the balance maintained within all living organisms)? Simply put, diseases are a departure from homeostatic balance. In any disease the natural mechanisms that help maintain homeostasis are overridden by the disease mechanism. This may be from another organism (a pathogen) or from some environmental source such as asbestos or lead exposure. Another class of diseases are caused by imbalances in cell function. These diseases are most often the result of changes in our DNA. Sickle cell anemia is an example of a disease caused by a single change in the sequence of our DNA. The various forms of cancer are also caused by specific imbalances in cell function. The specific functions that must be changed have been identified and collectively termed the Hallmarks of Cancer. In order for a tumor to establish itself and grow a number of checks and balances within the body must be overcome. Six hallmarks of cancer are generally accepted. While each hallmark is a step on the road to the formation of a tumor, any one hallmark will not lead to formation of cancerous tissue. 1) Cell Division without ‘go’ signals – oncogene Cells normally receive signals from the body that initiate and division (mitosis). There are many mechanisms that accomplish this . If a cell begins to divide without these external signals it has started on the road to cancer.

2) Ignoring ‘stop’ signals from neighboring cells – mutations When cells reach maturity or when they become crowded their neighboring cells send signals out to stop their further division (mitosis). If a cell fails to ‘listen’ to these signals due to a it is one step further toward tumor formation.

3) Immortality – Strangely enough we begin life with cells that do not age. The secret of immortality is lost by cells as we develop (stem cells retain this ability). The mechanisms of immortality are turned off in our cells but remains in their DNA code. Certain mutations allow cells to regain this ability – another step toward cancer.

4) Avoiding Death – When cells stray too far from homeostasis they are sent signals that initiate . Apoptosis is a term used for the release of enzymes from the lysosomes that causes the cell to effectively commit suicide. A cell that no longer ‘listens’ to these signals is just that much closer to becoming cancerous.

5) – Any cell that is growing and dividing rapidly uses a lot of ATP. Nutrients and oxygen are the fuel that the cell uses to produce ATP. Blood vessels are the transport mechanism for the acquisition of nutrients and oxygen. As cells move toward becoming tumor s they must recruit new blood supplies. This process of recruiting new blood vessels is called angiogenesis and is one more necessary part of the pathway to cancer.

6) – become deadly when they spread. The ability of cancerous cells to spread to other tissues in the body is termed metastasis. As cancerous cells metastasize they have become fully functioning tumors.

Background5-12HallmarksofCancer2012 Text 2012 Greg Ballog Page 1

Name ______Date ______Period ______Points Earned Title of Reading: 5-12 The Hallmarks of Cancer 1 2 3 4 5 6 7

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A) What one question do I have about this article?

1 Point A & B B) Show or describe the reading to a parent or guardian (Name ______). What comments or questions did they have concerning the reading? (Biology Homework Time ______) # Answers

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Background5-12HallmarksofCancer2012 Text 2012 Greg Ballog Page 2