Control of the Cell Cycle

8.3 page 211

• Read pages 211-213 in your text• Answer questions 1-5 page 213

Normal control of the cell cycle

• The cell cycle is controlled by proteins called cyclins and a set of enzymes that attach to the cyclin and become activated.

• The interaction of these molecules, based on conditions both in the cell’s environment and inside the cell, controls the cell cycle

• Each group of cyclins regulate if a cell is ready to move into the next phase of the cell cycle

When cells lose control

• Occasionally, cells lose control of the cell cycle• This uncontrolled dividing of cells can result

from:– the failure to produce certain enzymes– the overproduction of enzymes– the production of other enzymes at the wrong

time

result

• Cancer • Cancer is a malignant growth resulting from

uncontrolled cell division of abnormal cells• Cells become cancer cells because of damage

to DNA• This loss of control may be caused by

environmental factors (ex. Tobacco use) or by changes in enzymes production

• Cancer cell growth is different from normal cell growth

• Instead of dying, cancer cells continue to grow and form new, abnormal cells.

• Cancer cells can also invade other tissues, something that normal cells cannot do

• Growing out of control and invading other tissues are what makes a cell a cancer cell

• In most cases, cancer cells form a tumor

Review………

•Cancer, then, is a disease in which a single normal body cell undergoes a genetic transformation into a cancer cell.

What is cancer animation

• http://www.youtube.com/watch?v=LEpTTolebqo

MD Andersen informative cancer video

• http://www.youtube.com/watch?v=j_wRpa2b5XI

Characteristics of cancer cells

• 1. cancer cells are genetically unstable• 2. cancer cells do not correctly regulate the

cell cycle• 3. cancer cells escape the signals for cell

death• 4. cancer cells can survive and proliferate

elsewhere in the body

Proto-oncogenes and tumor suppressor genes

• These genes control the cell cycle• Proto-oncogenes encourage cell division• Tumor suppressor genes inhibits cell division• Together, they coordinate the regulated

growth that normally ensures that each tissue and organ in the body maintains a size and structure that meets the body’s needs.

Mutated proto-oncogenes…

• Mutated proto-oncogenes become oncogenes• Oncogenes are genes that stimulate excessive

cell division• Mutations in tumor suppressor genes

inactivate these genes, eliminating the critical inhibition of cell division that normally prevents excessive growth. Also prevents apoptosis…(remember that word??)

• http://www.teachersdomain.org/asset/tdc02_vid_oncogene/

• http://www.youtube.com/watch?v=WXTsxPPcTEs

metastasis

• Cancer cells often travel to other parts of the body, where they begin to grow and form new tumors that replace normal tissue. This process is called metastasis. It happens when the cancer cells get into the bloodstream or lymph vessels of our body

How cancers differ

• Cancer is the general name for a group of more than 100 diseases in which cells in a part of the body begin to grow out of control

• No matter where a cancer may spread, it is always named for the place where it started

• Different cancers grow at different rates and respond to different treatments

Tumors that are not cancer

• Not all tumors are cancerous• Tumors that aren’t cancer are called benign• Benign tumors can not invade other tissues or

spread• Benign tumors can cause problems– They can grow very large and press on healthy

organs and tissues

Question:

• What is the difference between a benign tumor and a malignant tumor?

How common is cancer?

• Second leading cause of death in the USA exceeded only by heart disease

• Most common type of cancer is skin cancer (nonmelanoma skin cancer)

Largest tumor (according to internet)

• In August 2010, doctors removed a tumor weighing nearly four stone –24 kilos, or 56 pounds– from a woman in Argentina. It had been growing inside her body for 18 months. The huge growth was taken out of the 54-year-old’s womb during a four-hour operation at a hospital near the capital, Buenos Aires. The unnamed patient was discharged weighing just over 16 and a half stone – five stone 7lbs less than when she was admitted

• Scientists measure the impact of cancer in a population by looking at a combination of 3 elements:– Incidence rate: number of new cases per year– Mortality rate: number of deaths per year– Survival rate: proportion of patients alive at some

point after diagnosis

Cancer Type Estimated New Cases Estimated Deaths

Bladder 69,250 14,990

Breast (Female – Male) 230,480 – 2,140 39,520 – 450

Colon and Rectal (Combined)

141,210 49,380

Endometrial 46,470 8,120

Kidney (Renal Cell) Cancer 56,046 12,070

Leukemia (All Types) 44,600 21,780

Lung (Including Bronchus) 221,130 156,940

Melanoma 70,230 8,790

Non-Hodgkin Lymphoma 66,360 19,320

Pancreatic 44,030 37,660

Prostate 240,890 33,720

Thyroid 48,020 1,740

• Cancer researchers use the term lifetime risk to indicate the probability that a person will develop cancer over the course of a lifetime. In the USA, men have a 1 in 2 lifetime risk and women have a 1 in 3 lifetime risk of developing cancer.

Types of Cancer

• Carcinomas– Rises from epithelial layers (lining of external and internal

surfaces). Body organs. Most common. Ex. Breast, uterus, prostate, lung, mouth, stomach, colon, rectum, urinary tract

• Sarcomas– Arise from connective and fibrous tissue. Ex. Muscle, bone,

cartilage• Lymphomas

– Cancer of the lymphatic systemLeukemias

cancer of the blood cells

Causes of cancer

• Genetics. Causes “sporatic mutations”• Lifestyle factors (tobacco use, alcohol

consumption, diet, obesity, UV Exposure, physical activity, toxic wastes, asbestos, chemicals) “Carcinogens”. Called “somatic mutations”

• Certain types of viral infections• Environmental exposure to different types of

chemicals and radiation

Normal and smoker’s lungs comparison

Oral Cancers

Skin cancers

Skin cancer

• A- asymmetry• B- border• C-color• D- diameter• E- evolving

Colorectal cancer

Pancreatic cancer

Colorectal cancer• signs and symptoms of colon cancer include: • A change in your bowel habits, including diarrhea or constipation

or a change in the consistency of your stool• Rectal bleeding or blood in your stool• Persistent abdominal discomfort, such as cramps, gas or pain• A feeling that your bowel doesn't empty completely• Weakness or fatigue• Unexplained weight loss• Many people with colon cancer experience no symptoms in the

early stages of the disease. When symptoms appear, they'll likely vary, depending on the cancer's size and location in your large intestine.

Genetics and cancer

• Some people are born with mutations that directly promote the unrestrained growth of certain cells or the occurrence of more mutations

• Inherited characteristics such as fair skin, do not promote the development of cancer but make someone more susceptible

• Only 5-10% of all cancers are inherited• These tend to appear earlier in life• Ex. Breast and colon

Cancer prevention

• Be physically active• Eat fruits, vegetables, and grains• Limit your time in the sun• Know your body and recognize the warning

signs

Cancer treatment

• 3 major ways of treatment– Surgery- removing tumors– Radiation- slowing the growth of cancer by

preventing cells from reproducing– Chemotherapy- anti-cancer medication which

interferes with cell cycle

Question

• Why is early diagnosis and treatment of cancer important?