Cancer disease (2)

When good cells go bad

The Cell Cycle and Cancer

What is cancer?Caner is defined as the continuous

uncontrolled growth of cells .A tumor is a an abnormal proliferation of

cells.Benign tumors stays confined to its original

locationMalignant tumors are capable of invading

surrounding tissue or invading the entire bodyTumors are classified as to their cell typeTumors can arise from any cell type in the

body

This video shows what the cancer is

Animation: How Cells Reproduce (cancer)

Normal and Cancer cells

1. Click on picture for cell cycle animation – will go to www.cancerquest.org)2. Use alt-tab keys to go between website and power point presentation. 3. Click on blank space to proceed to next slide.)

Cancer continued; three cancer types Carcinomas; constitute 90% of cancers,

are cancers of epithelial cellsSarcomas; are rare and consist of tumors

of connective tissues (connective tissue, muscle, bone etc.)

Leukemias and lymphomas; constitute 8% of tumors. Sometimes referred to as liquid

tumors. Leukemias arise from blood forming cells and lymphomas arise from

cells of the immune system (T and B cells).

Some Major Types of Cancer

In general, a cancer is named according to the type of tissue in which it first forms

Sarcomas: cancer of connective tissue

Carcinomas: cancer arising from epithelium

Lymphomas: cancer of lymphoid tissue

Leukemias: cancer of stem cells

Gliomas: cancer of brain cells

Cancer is a disease of the cell cycle. Some of the body’s cells divide uncontrollably and tumors form .

Tumors in LiverTumor in Colon

While normal cells will stop dividing if there is a mutation in the DNA, cancer cells will continue to divide with mutation.

Due to DNA mutations, cancer cells ignore the chemical signals that start and stop the cell cycle.

2 animations of cancer cells dividing: click on picture

Normal cells show contact inhibition

Cancer cells lack contact inhibition

They keep growing

And growing

And growing

And growing

Cancer Spreads Step-by-Step

This Cancer Cell Is Surrounded by White Blood Cells

4Cell

division

Mitosis

3DNA

repair

G21

Cell grows, doubles in

sizeG1

S

2Chromosome duplication

G1/S checkpoint

p. 183

Outside cell

Receptor

Plasma membrane

Cytoplasm

Nucleus

Changes in gene expression

Signal molecule

Signal–receptor binding

Cellular response

Protein molecules

Stepped Art

• Benign: localized and of small size

• Cells that closely resemble, and may function, like normal cells

• May be delineated by a fibrous (Basal lamina) capsule

• Become problems due to sheer bulk or due to secretions (e.g. hormones)

Normal Moles Are Common Examples of Benign Growths

Malignant tumors: high rate of division, properties may vary compared to cells of origin. Most malignant cells become metastatic

Invade surrounding tissue and establishment of secondary areas of growth: Metastasis

Cancer : Malignant

Main Features of Benign and Malignant Tumors

SmokingNumber one factor in cancer, either direct

(smoker) or indirect (secondhand smoke) -Related to cancers of oral cavity, larynx,

esophagus, and lungsAccounts for 30% of all cancer deathsMost have very low survival rate (e.g. 13% lung

cancer sufferers survive beyond 5 yrs

Lungs of Non-Smoker and Smoker

Other Factors Also May Lead to Cancer

Chemical carcinogensCarcinogens: cancer-causing substances

that can lead to a mutation in DNAAsbestos, vinyl chloride, and benzeneHydrocarbons in cigarette smokeAflatoxin: fungal product

RadiationUV from the sun and tanning lampsX-rays: medical and dentalRadon, cosmic rays, and gamma radiation

X-rays

Skin Cancer (1)~1 million new cases in U.S. per year

Almost all cases related to UV light exposure from sun or tanning lamps

Increasing, may be due to outdoor recreation or moving to regions with more sun exposure

Lightly pigmented people higher risk, genetic characteristics can affect the susceptibility

Melanoma

Other Factors Also May Lead to Cancer

Chemical carcinogensCarcinogens: cancer-causing substances

that can lead to a mutation in DNAAsbestos, vinyl chloride, and benzeneHydrocarbons in cigarette smokeAflatoxin: fungal product

RadiationUV from the sun and tanning lampsX-rays: medical and dentalRadon, cosmic rays, and gamma radiation

Some Industrial Chemicals Linked to Cancer

Biopsy Is the Only Sure Way to Diagnose Cancer

BiopsyRemoval and microscopic examination of tissue

Seven common cancer signs: CAUTION

Cancer Treatment and Prevention

When a person is diagnosed with cancer, a variety of weapons are available to combat it

Chemotherapy drugs

Radiation therapy

Surgery

Chemotherapy and Radiation Kill Cancer Cells

Radiation therapyUsed when cancer is small or

has not spreadRadioisotopes used, e.g., Ra-

226 and Co-60

Chemotherapy and radiation destroy healthy cells

More precise treatmentsMonoclonal antibody treatmentInterferon treatment; limited at

present

Good Lifestyle Choices Can Limit Cancer Risk

Avoid tobacco completely

Maintain a desirable weight; eat a low-fat diet with plenty of fruits and vegetables

Make sure your living and work environment is safe from carcinogens

Protect your skin from the sun’s UV rays

.

SUMMARYNormal Cell Division

.1DNA is replicated properly.

2 .Chemical signals start and stop the

cell cycle.3 .Cells communicate

with each other so they don’t become

overcrowded.

Cancer Cells

.1Mutations occur in the DNA when it is

replicated.2 .Chemical signals that

start and stop the cell cycle are ignored.

3 .Cells do not communicate with

each other and tumors form.