Ch 26 Cancer

mitosis

- Happens after interphase!! separation of a nucleus and its nuclear chromosomes into into 2 identical nuclei a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

in normal cell cycle.. what would affect the cell from being classified as not a good cell so it gets stopped in the restriction point...

-A cell can be classified as not good if they are grown under bad conditions (ex: lack of growth factors, high density, lack of anchorage or inadequate nutrients), the cells get stopped at the restriction point and stop dividing. -If they have DNA damage, etc.

Apoptosis

-A type of cell death -self-destruction

It is known that cancer cells create tumors. What procedure was done to help test how cancer cells are compared to normal cells (when it has to do with creating tumors)

-By injected cancer and normal cells to nude mice, which lack an immune system. Normal human cells injected into the mice won't grow but cancer cells proliferate (producing in excess without them dying or stop dividing) and form tumors.

What is the "seed and soil" hypothesis?

-Hypothesis proposed by Stephen Paget -It says that cancer cells are carried around the body, but only a few sites provide an optimal growth environment for each type of cancer

how the Restriction point different in normal cells VS cancer cells?

-In normal cells... If normal cells are grown under bad conditions (ex: lack of growth factors, high density, lack of anchorage or inadequate nutrients), the cells get stopped at the restriction point and stop dividing. Cancer cells... they continue to proliferate (divide endlessly) even if conditions are extremely not ideal (ex: conditions with extreme nutritional deprivation) and they arent stopped at restriction points. This is bc the cell cycle controls (like the restriction points) in cancer don't work properly

Explain the difference between the growth of normal cell VS cancerous cells in CULTURES (osea in the lab)

-Normal cells grown in culture divide a limited number of times. After the number of times, they die. -Under similar conditions, cancer cells exhibit no such limit and continue dividing indefinitely and act like theyre immortal.

endothelial cells

-They are cells that surround blood vessels. They create a thin layer around blood vessels that is known as Endothelium. -they have receptors where VEGF and FGF can bind to

What are metastases?

-Tumors formed in new locations -they arent connected physically to the primary tumor.

Blood vessel growth is controlled by what?

-by a balance between angiogenesis activators (help produce new blood vessels) and inhibitors (restrain the growth of blood vessels)

Lymphomas

-come from blood cells and have and lymphatic origin -Lymphomas are tumors that grow as a solid mass

Why can cancer cells divide indefinitely but normal cells can only divide a limit amount of times?

-if a normal cell divides too many times, its telomere shortens and becomes too short to protect the ends of the chromosomes. So, a pathway is triggered that stops cell division and may even destroy the cell by apoptosis. -this telomere shortening prevents excessive proliferation of adult cells and helps explain why normal cells can only divide a limited amount of times. --- Most cancer cells produce telomerase, the enzyme that adds telomere sequences to the ends of DNA molecules

What happens to the cell that moves from the basal layer up towards the skin surface?

-it flattens and starts to make keratin. -eventually (the more it goes up), the cell dies and is shed from the outer skin surface

when growing in the body, most normal cells meet anchorage requirement(to survive bc some cells NEED some sort of anchorage to survive)?

-it happens by binding to the extracellular matrix through integrins (proteins in the surface of cells) -If cells that havent meet the anchorage requirements cant attach to the matrix (due to chemicals that block the binding of integrins to the matrix) they will loose the ability to divide and will self-destruct by apoptosis.

What is a restriction point?

-it is a part of the cell cycle which controls the continuation from G1 to S phase -osea its a checkpoint a ver si el cell continues to divide or it will stop dividing. -A cell can be classified as not good if they are grown under bad conditions (ex: lack of growth factors, high density, lack of anchorage or inadequate nutrients), the cells get stopped at the restriction point and stop dividing.

What is Angiogenesis?

-its the formation of new blood vessels. -these new blood vessels form from pre-existing vessels.

Leukemia

-like the lymphomas... bc they arise from cells of blood and some have lymphatic origin -but!! leukemia has to do mainly in the bloodstream

Cancer cells spread by what two things?

-metastasis and invasion. Metastasis: the ability of cancer cells to enter the bloodstream and travel to distant sites Invasion: the direct migration and penetration of cancer cells into neighboring tissues

Carcinomas

-one of the categories of cancer -90% of all cancers are carcinomas -arise from epithelial cells covering external and internal body surfaces

What study first helped prove that blood vessels in cancer cells are stimulated more VS blood vessels in animals that have normal cells?

-studies in which cancer cells were added to chamber (como un container/una cosa pequena) that was surrounded by a filter with small pores that normal cells can't pass through. -These chambers were inserted into animals and then they saw that the animal started to proliferate (divide and reproduce rapidly) new capillaries in the host's surrounding tissue. VS -But when the same thing was done but with a chamber with normal cells.. this didn't cause anything different. - Osea they did not stimulate blood vessel growth. THIS CONCLUDED THAT: Cancer cells produce molecules that diffuse through the tiny pores in the filter and activate angiogenesis (its the formation of new blood vessels) in the surrounding host tissue

What are the two experiments that proved Tumors need blood vessels to grow into a big size?

-studies involving cancer cells grown in isolated organs. 2 different experiments: 1: a normal thyroid gland was removed from a rabbit and placed in a glass chamber. A small number of cancer cells were injected into the gland and a nutrient solution was pumped into the organ's main blood vessel to keep it alive. -During this experiment, cancer cells divided for a few days but then stopped randomly when the tumor reached a diameter of 1-2 mm. Every tumor stopped growing at that exact same size. This suggested that some kind of limitation allowed them to grow only so large. -When tumor cells were removed from the thyroid gland and injected back to animals, cell division continued and the tumors grew so big. This occurred bc the small tumors in the thyroid gland didn't link to the organ's blood vessel pero when added to alive animals that could connect to blood vessels and grow. ----------- Second Experiment: -Folkman (scientist) put cancer cells in the eyes of rabbits. -rabbits don't have blood vessels in their eyes so this would test if blood vessels were needed for tumor growth. -The tumors were small and did not grow to a big size. Then, the same cancer cells were implanted in the iris of the eye where there are a lot of blood vessels and the tumors grew super big.

What is cancer "Invasion"?

-the direct migration and penetration of cancer cells into neighboring tissues

what is Telomerase?

-the enzyme that adds telomere sequences to the ends of DNA molecules -Most cancer cells produce telomerase so they can reproduce and divide indefinitely without apoptosis being triggered or without them loosing their ability to continue dividing.

Basal layer of skin

-the inner bottom layer -new replacement of skin cells happens bc of cell divisions that happen in this layer in the skin.

why is apoptosis important?

-triggering apoptosis for normal cells who could not properly anchor helps for these cells not to go to other parts of the body and attach to other tissues, where they dont belong. -this does happen in cancerous cells bc they arent anchor dependent so they dont trigger apoptosis and get away with it. -so, many random cells float and attach to tissues that dont need them (hacen tumors)

How do tumors have such dense network of blood vessels?

-tumors release signaling molecules that trigger angiogenesis (the growth of blood vessels) in the surrounding host tissues. -these new blood vessels are important bc theyre required for tumors to grow and not stay as tiny, localized clump of cells.

What property of cancer cells make them so dangerous?

-yes, cancer cells divide uncontrollably but that is not what is dangerous (bc benign tumors proliferate uncontrollably but they arent dangerous) -but! benign tumors's cells divide in one location and dont spread apart. They are usually very easy to remove. ------ -So, what makes it dangerous is that cancer cells proliferate uncontrollably AND they spread out in many different parts of the body. This makes it super hard to remove!

What are factors that allow the cancer cells to continue dividing

1. -Cancer cell cycle controls (like the restriction points) don't work properly. These cycle controls would normally stop the cell from dividing and it would kill it but it doesn't. Cancer cells are unresponsive to external signals and to internal conditions (like DNA damage) that would normally trigger a stop to the cell cycle. 2. For some cancers, uncontrolled growth is due to a failure to undergo apoptosis (cell death). They instead increase cell division Cancer cells are able to block the pathways that trigger apoptosis in various ways

Explain the process of Metastasis

1. Angiogenesis (formation of new blood vessels) 2. cancer cells invade surrounding tissues and gain access to the bloodstream 3. they are transported throughout the body 4. they leave the bloodstream and establish new metastatic tumors in various organs -All of these steps have to be done or else metastasis doesnt happen.

Cancer Arises Through a Multistep Process Involving what three steps?

1. Initiation 2. Promotion 3. Tumor Progression

What are the 3 steps of cancer development?

1. Initiation Initiation is the process where normal cells are converted into a precancerous state and sensitized to further change. 2. promotion: Long, gradual process where sensitized cells are repeatedly exposed to cancer-promoting agents 3. Tumor Progression: Process where once a tumor has formed, the tumor grows and differentiates.

what are characteristics that distinguish cancer cells from normal cells?

1. cancer cells create tumors. 2. Normal cells dont grow in culture (como en el lab) when they are spread in a medium that is liquid or semi-liquid. But they start to divide when they are added to a medium that has a solid surface bc they spread out and attaches to the solid surface. BUT cancer cells grow in a medium that has any type of surface. (pueden estar freely suspended in a liquid or semi-liquid or "anchored" in a solid surface) This is called anchorage-independent growth.

How do tumors occur?

A cancer is a type of growth in which some cells divide and accumulate in an uncontrolled way. This causes a lot of dividing cells. A tumor is the resulting mass of the growing tissue (de los dividing cells)

What is cell anchorage?

Anchorage is when cells adhere to or are in contact with another layer of cells. The cells can be adhered to other cells, extracellular matrix, or tissue culture plastic (via proteins). Many cell types require some sort of anchorage in order to survive.

What is required for a tumor to grow beyond a few millimeters in diameter? How does it happen?

Angiogenesis (the formation of new blood vessels from pre-existing vessels) -This is needed for tumors bc he new blood vessels are needed for tumors to grow

As cells acquire their traits in cell differentiation.. que pasa despues?

As cells acquire these specialized traits, they lose the capacity to divide

Bening VS malignant tumors:

Benign tumors grow in a specific, local area and are rarely dangerous Malignant tumors can spread to surrounding tissues and other parts of the body/new locations.

What are the types of tumors? (2)

Benign tumors: -grow in specific area (dont spread to other parts of body) -rarely dangerous Malignant tumors: capable of invading surrounding tissues and spreading to distant parts of the body

______and ______ Factors Determine Sites of Metastasis

Blood Flow and Organ-Specific Factors Determine Sites of Metastasis

What moves the cancer cell through the body?

Cancer cells can circulate in the bloodstream, they exit the wall of a tiny blood vessel and invade different organs.

What is different of the molecules cancer cells produce?

Cancer cells produce small proteins that are angiogenesis (its process of the formation of new blood vessels) activating molecules. These molecules that diffuse through even through tiny pores and activate angiogenesis (its the formation of new blood vessels) in the surrounding host tissue. (normal cells dont do this)

Cancers are grouped into several categories What are they?

Carcinomas: 90% of cancers are carcinomas, arise from epithelial cells covering internal and external body surfaces Sarcomas Lymphomas leukemias: like lymphomas bc arise from blood cells but have to do more in the bloodstream

what causes cancer cells divide?

Cells divide when they are stimulated by the proper growth factor. -cancer cells find a way around this by altering signaling pathways, creating a constant signal to divide -Disruption of cell cycle control also contributes to cancer cell proliferation

What causes the cell to divide/ proliferate?

Cells divide when they are stimulated by the proper growth factor. Osea cell proliferation is regulated by protein growth factors that bind to the cell surface receptors and activate signaling pathways within the targeted cells. -cells do not divide unless they are stimulated by the proper growth factor.

Epithelial cells

Epithelial cells make up the lining of hollow organs and glands, as well as skin and other enclosed organs. These cells are packed on top of each other in various ways (columnar, cuboidal, squamous etc.)

What do epithelial cells have to do with cell anchorage?

Epithelial cells make up the lining of hollow organs and glands, as well as skin and other enclosed organs. These cells are packed on top of each other in various ways (columnar, cuboidal, squamous etc.) They ARE anchorage dependent, they will die if they are no longer adhered to other cells - this is referred to as anoikis.

What are the 2 main cellular defects that play a central role in cancer.

Gene mutations and changes in gene expression

Metastases develop preferentially at certain sites. What things can tell you where these preferable "sites" will be?

Has to do with the blood flow!! 1. Most of the circulating cancer cells will go into the nearest capillary first. 2. They will get stuck in a capillary (bc they are so small/tight) and then will penetrate their walls. 3. The cancer cells will after enter the surrounding tissues outside of that area in the capillary and invade it making tumors. pero todo depende del blood flow bc it could be different organs.. solo se sabe que it will be preferably invade the organ outside of the capillary area it is in. ----- ALSO HAS TO DO WITH Organ-Specific Factors -environment provided by organs affects is Metastases will happen. -only a few sites provide an optimal growth environment for each type of cancer

Relationship between Cell division, cell differentiation & death in NORMAL CELLS & TUMOR CELLS

In normal cells: Cell division is carefully balanced with cell differentiation and death In tumors: cell division is different (has no connection from cell differentiation and death

Normal cell growth in skin VS tumor growth

In normal skin, one of the two cells produced by each division can still divide. The other cell leaves the basal layer (the bottom layer of the skin), cant divide anymore and dies. So, no more unnecessary cell division ------ In tumors: cell division is has no connection from cell differentiation and death. osea in cell division, cells dont stop dividing or dying. So, tumors continue to grow bc of the constant cell division.

epithelial cells functions (in vertebrates)

In vertebrates: it lines the outer layer of the skin (epidermis), the surface of most body cavities the lumen of fluid-filled organs, such as the gut or intestine.

Who initially proposed that tumors release signaling molecules and that triggers angiogenesis?

Judah Folkman in 1971

What is the most common organ that is a preferable site of metastases development?

LUNGS! bc for primary tumors that are in most organs. After blood cells enter the bloodstream, the capillary bed they will encounter is the one in the lungs. ---- BUT some blood-flow patterns will not always go in the direction of the lungs. For the stomach cancers and in the colon, the preferred site is the liver!

Cancer cells of Primary tumors' preferred metastases site is ___

LUNGS.

why is cell anchorage important?

Many cell types require some sort of anchorage in order to survive. Therefore, if an anchorage dependent cell is not adhered and floating around, it will die.

Explain como pasa el cell division and cell differentiation in the skin

New cells continually replace aging cells shed from the outer body surface New cells are generated by cell divisions in the basal layer of the skin One stays in the basal layer and can still divide

What type of cell (cancer or normal cell) has the density-dependent inhibition of growth?

Normal cells... -Cancer cells continue to divide and pile up upon one another. So they dont have sensitivity to density-dependent inhibition

When a basal cell divides, it gives rise to two cells.. CUALES SON

One stays in the basal layer (bottom layer of skin layers) and can still divide One differentiates(so cant divide) and moves toward the skin surface

What is density-dependent inhibition of growth?

Process where cells grown in culture divide until the surface of the vessel is covered by a single layer of cells Once this monolayer stage is reached, cell division stops. This is called: density-dependent inhibition of growth -Normal cells are like this. Cancer cells aren't! They divide and divide... (doesnt stop) the cells pile up.

Roughly 90% of cancer deaths are caused by ___

Roughly 90% of cancer deaths are caused by the spread of the cancer rather than the primary tumor

Differentiated cell types.. que es? que tiene que ver en el cuerpo?

The body is made up of different types of cells. ex: nerve, muscle, blood, cartilage and fat. They are different between each other bc of their differences in their microscopic appearance, and in what products they produce.

Explain process of how blood vessels grow

The main angiogenesis-activating molecules are called: vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) 1. VEGF and FGF are released by cancer cells into the surrounding tissue bind receptors on endothelial cells that are surrounding blood vessels. 2. They stimulate proliferation (rapid division) and secretion of matrix metalloproteinases (break of extracellular matrix) 3. This allows the endothelial cells to move into the surrounding tissues. 4. As they migrate, the proliferating endothelial cells become organized into hollow tubes and they later become into new blood vessels. This grows of blood vessels into the tissue.

What are integrins?

They are cell surface proteins

HeLa cells

They are cells from a uterine cervical cancer of Henrietta Lacks. They were isolated in 1951 and have been dividing in culture for more than 50 years.

What are the 2 main angiogenesis-activating molecules?

They are: - vascular endothelial growth factor (VEGF) -fibroblast growth factor (FGF)

Tumors Arise When ______

Tumors Arise When the Balance Between Cell Division and Cell Differentiation or Death Is Disrupted

Tumors possess a dense network of ________

Tumors possess a dense network of blood vessels.

what is anchorage-independent growth?

When cells grow well not only when anchored to a solid surface but also when suspended in liquid or semisolid medium -like cancer cells. .... normal cells dont do this.

what is gene expression?

When the information stored in our DNA is converted into instructions for making proteins or other molecules.

What main thing creates cancer?

abnormalities of cell function

Sarcomas develop from what? (5)

develop from: supporting tissues, bone, cartilage, fat, and muscle

interphase.. describe ALL phases.

interphase: cell growth but no cell division most cells live here -cancer cells divide not grow so no interphase G1: first phase of the interphase -longest phase of the cell cycle -growth cycle -produce extra organelles such as ribosomes and proteins. -in this cycle, the cell has a choice.. if it wants to continue growing and move towards the S phase. (more growth0 or G0 G0: after G1... -no more cell division happens.. -wont come back to the cell cycle ex: neurons.. they d S phase: stands for synthesis.. -DNA sythesis... bc here is where DNA replication occurs... where 23 pairs of chromosomes (half of the chromosome is from mom, half of the chromosome is form dad) and we duplicate the, so it creates 46 pairs. G2: after S phase -more directly preparing for mitosis -make microtubules. used to pull chromatids apart in anaphase (phase in mitosis) After.... mitosis: (M) active cell division -once divided, it enters the G1 phase

What is Cell Differentiation?

is the process by which cells acquire specialized properties osea they all start from immature, nonspecialized cells y then they pass though Cell Differentiation y los cells become more specialized cells: ex: ex: nerve, muscle, blood, cartilage and fat cells.

What happens after a basal cell divides?

it gives two cells with different fates: -once cell can stay in the basal layer and continues to divide or -it can leave the basal layer and goes up towards the outer skin surface and it cant divide anymore

What are the three most common cancers of the carcinoma category?

lung breast colon

What are matrix metalloproteinases?

matrix metalloproteinases are enzymes that break extracellular matrix

Are benign tumors cancer?

no! only malignant tumors are classified a cancer bc benign tumors aren't dangerous.

Do tumor cells divide more rapidly than normal cells?

not always. The crucial issue is not rate of division but the balance between division and differentiation or cell death osea cell division doesnt stop or cells dont die.. so there is way more at the end. no tiene nada que ver con the speed of it.

Interphase

nterphase: cell growth but no cell division most cells live here -cancer cells divide not grow so no interphase -4 possible phases... G1, G0 and S- phase and G2

Primary tumors

original tumors... the main tumor

What is Metastasis?

the ability of cancer cells to enter the bloodstream and travel to distant sites

Where is a common site of metastases for stomach and/or colon cancers?

the liver! bc the cancer cells entering the bloodstream from the stomach or colon will go towards the liver where there is a capillary bed.

Cell proliferation

the process that results in an increase of the number of cells, and is defined by the balance between cell divisions and cell loss through cell death or differentiation. Cell proliferation is increased in tumors.

epithelium

the thin tissue forming the outer layer of a body's surface and lining the alimentary canal and other hollow structures (like blood vessels)

What is a defining feature of cancer cells?

their uncontrolled proliferation. (divide uncontrollably) -yes, cancer cells divide uncontrollably but that is not what is dangerous part (bc benign tumors proliferate uncontrollably but they arent dangerous)

where in the body do cancers originate?

they can be in almost any organ

capillaries

tiny vessels with the diameter that is not bigger than a blood cell.

Though the bloodstream carries cancer cells throughout the body, metastases develop preferentially at certain sites (areas) TRUE or FALSE?

true.