Exam 1

Question 1

What are the three most common fatal cancers in men and women?

Answer 1

lung, breast (females)/prostate (males), and colorectal

Question 2

What is the lifetime risk for developing any cancer in men and women?

Answer 2

1:2 for men and 1:3 for women

Question 3

Compare per capita cigarette consumption and rates of lung cancer

Answer 3

during the 1980s there was a dramatic increase in deaths due to lung cancer in men due to an increase in smoking. This trend was also seen in women around the 2000s. The increase in smoking was due to advertisements from tobacco companies and world wars. There was a 10 year lag for the effects to be seen.

Question 4

What led to an increase in incidence of cancer for men and women between 1975 to 2016?

Answer 4

In the 1980s there was a large increase in incidence of prostate cancer for men due to a new test discovered that would allow doctors to detect more prostate cancer than before. The levels of incidence for prostate cancer were probably always that high. This was also seen in breast cancer incidence in women in the 1960s when the acceptance of mammograms and routine screening began.

Question 5

Who and when published the 6 characteristics of the cancer cell? When did the revisions occur?

Answer 5

Hanahan and Weinberg first in 2000, then revised in 2011

Question 6

What are the 6 characteristics of the cancer cell

Answer 6

Self-sufficiency in growth signals: cancer cells are not dependent on growth factors to bind to their receptors to tell them to divide. If there was a mutation in RAS so that the intrinsic GTPase activity was lost then RAS would always be on and there would be no use for a mitogen. Insensitivity to growth-inhibitory signals: cancer cells don’t have cadherins and therefore the cells cannot tell when they have reached confluent growth. Evasion of apoptosis: over 50% of all human cancers have a mutated p53 which would detect the severity of DNA damage and decide if the cell’s DNA is beyond repair and needs to undergo apoptosis. without a functioning p53 then this regulation will not occur. Limitless replicative potential: cancer cells are able to reactivate telomerase in order to extend their telomeres and overcome the Hayflick limit. Sustained angiogenesis: in order to supply the tumor with enough nutrients and oxygen the tumor will stimulate angiogenesis to occur towards the tumor. Tissue invasion and metastasis: cancer cells can move through the circulatory system and attach to a new location and begin to grow. It will do this by first reaching the basement membrane. Then it will pull its integrins in and dissolve the proteins of the basement membrane and the extracellular matrix by using matrix-metalloproteinases.

Question 7

What are the 2 additional characteristics of the cancer cell?

Answer 7

Increased glucose transportation/utilization: cancer cells will undergo Warburg metabolism which means that under all conditions (aerobic or anaerobic) it will undergo substrate level phosphorylation in order to meet energy demands by inhibiting pyruvate dehydrogenase with PDK-1, preventing Krebs cycle and ETC, and increasing the amount of GLUT1 transporters in the membrane, done by increased expression of ras. This will also increase byproduct molecules necessary for cell division such as those found in the PPP. Evasion of the immune system: cancer cells express PD-L (Programmed cell death ligand) to bind to PD-1 receptor on immune cells thereby causing the immune cells to undergo apoptosis.

Question 8

Why can you monitor cancer cell growth by its pH?

Answer 8

because it undergoes substrate level phosphorylation under all conditions (Warburg metabolism). Substrate level phosphorylation creates a lot of lactate that will increase the pH

Question 9

Benign vs malignant growths

Answer 9

benign growths are those that grow locally without invading adjacent tissues (end in -oma). while malignant growths invade nearby tissues and spawn metastases.

Question 10

Rous’ discovery

Answer 10

In the early 1900s, a farmer approached Payton Rous about their chickens having tumors. Trous took a sample from the chicken tumor, ground it up, and injected the ground up cells into another chicken. That second chicken formed a tumor. Rous then took a sample fo the chick tumor, ground it up, and filtered the cells and bacteria out of it. He then took that concoction and injected it into another chicken. that second chicken formed a tumor. Therefore, Rous deduced that it was a virus, called Rous Sarcoma Virus, that was causing the cancer in chickens.

Question 11

Permissive host vs non-permissive host

Answer 11

a host that allows a virus to enter and multiply is a permissive host. a host that allows the virus to enter but does not allow it to multiply is a non-permissive host

Question 12

Simian Virus 40 (SV40)

Answer 12

a DNA virus that is permissive in monkeys and non-permissive in rodents. If rodents are infected there is a chance the virus will un-coat itself, insert its DNA into the rodent genome but then will be unable to take over the rodent cell and therefore the viral chromosome will be incorporated into the rodent’s genome. If the Large T-antigen gene is incorporated into the rodent genome so that when the rodent cell devides the T-Ag protein will be made and it will inhibit Rb and p53 function causing unregulated cell division.

Question 13

Large T-Antigen

Answer 13

gene found in the SV40 viral genome that will cause inhibition of Rb and p53 function in rodents

Question 14

Adenovirus

Answer 14

family of DNA viruses that can cause common cold symptoms in its permissive host, humans, but can cause cancers in its non-permissive host, rodents. The adenovirus has viral proteins that will interact with Rb and p53 leading to unregulated division of rodent cells.

Question 15

Hepatitis B

Answer 15

is a DNA virus associated with liver cancer in humans. While most of the time humans who get hepatitis B are either asymptomatic or can fight the virus off there are a slim few who are unable to fight it off. Hepatitis B viral proteins will increase methyl transferase activity within the human cell turning tumor supressor genes off.

Question 16

Richard Shope

Answer 16

did the same experiment as Payton Rous but in rats, he found Shope Papilloma Virus. This caused people to think that because cancer can be caused by viruses and viruses are a communicable disease therefore cancer is communicable.

Question 17

Why are we not at risk from aerosols when using cancer lines in lab?

Answer 17

our immune system will mount a response against foreign cells

Question 18

How can we study metastasis

Answer 18

take a tumor cell and inject them into the tail of a mouse, two weeks later you dissect the mouse and look for metastasis. this is commonly done with melanoma cells because they are darkly pigmented.

Question 19

What percentage of all cancers are viral associated

Answer 19

up to 15%

Question 20

What was the experiment that demonstrated the integration of SV40 DNA into the genome of its host cell?

Answer 20

by using density gradient centrifugation of DNA the integration of SV40 DNA into the genome of a rodent cell was found. In a control test tube SV40 and normal mouse cell DNA was put and centrifuged. There were two distinct separate lines where SV40 and mouse DNA was found. In the experimental test tube they took mouse DNA that was transformed by SV40 and a SV40 probe and centrifuged them. There was one distinct line where the SV40 probe and the transformed mouse DNA sat. Therefore, it was assumed that the transformed mouse DNA took parts of the SV40 DNA.

Question 21

Human Papilloma Virus

Answer 21

family of DNA viruses. before the vaccine was distributed 80% of US women were effected by age 50. it has viral proteins that will disrupt Rb and p53

Question 22

Epstein-Barr

Answer 22

caused by herpesvirus 4. associated with Burkitts’ lymphoma and nasopharyngeal carcinoma.

Question 23

Burkitts’ lymphoma and Epstein-Barr disease

Answer 23

If you are in a region of Africa and infected with Epstein-Barr then Burkitts’ lymphoma is possible but if you’re in the US and infected with Epstein-Barr then Burkitts’ lymphoma is not found. There is some cofactor that leads to this difference. The mosquito/malaria region of Africa and the area of Africa where Burkitts’ lymphoma is common overlaps. Therefore some believe that being infected with malaria increases the amount of lymphocytes and therefore will cause them to be more susceptible to Burkitts’ lymphoma.

Question 24

Transforming viruses

Answer 24

RNA virus that will immediately cause a tumor due to the placement of a v-oncogene

Question 25

V-oncogene

Answer 25

an oncogene from a virus that has been mutated

Question 26

Cis-acting viruses

Answer 26

RNA virus that take a while to form a tumor by inserting its viral genome filled with strong promoters and enhancers near an oncogene

Question 27

Who found out and how did they find out that RSV was an RNA virus

Answer 27

Around the 1970s Baltimore, Dulbecco, and Temin found that RSV was a retrovirus. They had a petri plate of cells, they infected one cell with RSV leading to a foci. They wanted to know if it was by chance that the foci appeared or if it was due to the virus. They found a temperature sensitive mutant RSV copy. If grown at 37 degrees the virus was able to thrive but if it was grown at 41 degrees it would not be able to. They found that by infecting one cell with the mutant RSV copy at 37 degrees that the foci would develop but at 41 degrees it would not develop and the foci would convert back to normal cells. this showed that there’s at least one RNA viral protein that was needed for transformation.

Question 28

Avian Leukosis virus (ALV)

Answer 28

causes disease, but no sarcoma, in chickens.

Question 29

ALV and RSV

Answer 29

ALV and RSV are genetically similar but only RSV is able to cause sarcomas due to the presence of the src gene

Question 30

Src gene

Answer 30

found in RSV and will cause carcinomas, it is a protein kinase needed for cell division

Question 31

Bishop and Varmus

Answer 31

They discovered, through subtractive hybridization, that the src gene causes sarcomas. They took RSV RNA and transcribed the ssRNA to create cDNA. They then destroyed the RNA strand. They then took DNA from ALV and hybridized it with the cDNA of RSV. If a gene was found in both the cDNA of RSV and the DNA of ALV then it will yield a double strand. Thus subtracting all the genes that are similar between the two. If there was a gene found in only the cDNA of RSV then it will have no binding partner and will stay single stranded. They found that the src gene was the only gene that stayed single stranded. They knew that RSV causes sarcomas while ALV did not and therefore the src gene, found only in RSV, was the determining gene

Question 32

Src gene lineage

Answer 32

using src gene as a probe in other organisms it was found that the src gene is in many organisms and that it corresponded to the phylogenetic tree therefore it was present very early on in evolution and therefore it must have a function. They deduced that ALV infected a chicken cell, integrated into the chicken genome and by chance integrated right next to c-src. After some time it left the chicken cell but instead of copying just the ALV genome it also copied the src gene. This created the RSV.

Question 33

How are v-oncogenes originate

Answer 33

mistake and chance, once they are integrated into the viral chromosome they can be mutated yielding v-onc

Question 34

How can ALV cause sarcomas?

Answer 34

it will land close to an oncogene and cause over expression of the oncogene. Scientists looked at chickens who had ALV and tumors and looked to see where the ALV chromosome integrated into the chicken’s genome. They saw that the chromosome integrated in the c-myc gene. the promoter and enhancer activity of the ALV chromosome blend into the adjacent gene, and in this case the c-myc gene. This leads to an overproduction of the c-myc gene.

Question 35

Describe the relationships between cyclins, CDK, Rb, E2F, p53, and the cell cycle

Answer 35

There’re many types of cyclins that will bind to a cyclin dependent kinase (CDK) at different points in the cell cycle. In G1, cyclin D once bound to a CDK will phosphorylate retinoblastoma (Rb). Once Rb is phosphorylated twice it will release E2F, a transcription factor for many genes associated with cell division. p53 is another transcription factor that is a checkpoint inhibitor in the cell cycle. It will recognize damage to the cell’s DNA and stop the cell cycle until it is resolved. It stops the cell cycle by regulating the transcription of p21 which regulate levels of CDK.

Question 36

What are the steps involved from the activation of a RTK to the activation of a transcription factor

Answer 36

when epidermal growth factor (EGF) binds to the RTK the RTK becomes activated and becomes a homodimer. The tyrosine kinase shows auto-phosphorylation activity phosphorylating the RTK. Once phosphorylated the GRB2 will come and the SH2 domain will bind to the phosphorylated tyrosines. SOS will then bind to the SH3 domain of the GRB2 and then will bind a one subunit g-protein called RAS and activating it. As soon as RAS touches SOS, SOS will act as a guanosine exchange factor by exchanging the GDP on RAS for a GTP. The activated RAS will then associate with RAF, a protein kinase found within the cell. The intrinsic GTPase activity of RAS will lead to it deactivating. RAF will then phosphorylate MEK. MEK will phosphorylate a mitogen activated protein kinase (MAP Kinase). MAPK will then phosphorylate transcription factors.

Question 37

Receptor tyrosine kianse

Answer 37

is a homodimer when activated but two individual polypeptides when inactive. It contains 3 functional domains including a ligand binding domain on the extracellular side, a transmembrane domain, and a tyrosine kinase domain on the intracellular side

Question 38

GRB2

Answer 38

is an adapter protein with two domains: a SH2 domain that is used to locate and bind to phosphorylated tyrosines, and a SH3 domain that will bind to another adaptor protein called SOS

Question 39

3 types of growth factors that operate through RTK’s

Answer 39

epidermal growth factor, platelet derived growth factor, fibroblast growth factor

Question 40

Integrins

Answer 40

are found throughout the epithelial cell membrane and will bind to collagen, laminin, and other proteins found in the extracellular matrix. The cell will use integrins to adhere to the basement membrane

Question 41

Fibronectins

Answer 41

are dimers with multiple domains including: collagen binding domains, fibrin binding domains, heparain binding domains, ect. They will be used to anchor the cell to everything

Question 42

Fibronectins and a petri plate

Answer 42

if you make a streak of fibronectins on the bottom of a petri plate and then try to grow cells the cells will grow across the streak because they like to grow on something

Question 43

Cadherins

Answer 43

are protein dimers that cause cells to stick together in the presence of calcium

Question 44

Collagen

Answer 44

are proteins that are used for structure components of tissues

Question 45

What do you have to do in order to move cells between containers in lab

Answer 45

the cells are cadherin dependent therefore when they have covered the entire surface they will stop growing. one must dissolve the cadherins using trypsin (a protease) or get rid of the calcium using EDTA

Question 46

How can oncogenes arise

Answer 46

amplifications, translocations, missense mutations

Question 47

Her2 Breast cancer

Answer 47

Her2 is a type of receptor for epidermal growth factor that stimulates cell division. Her2 can become an oncogene due to amplification. When it is amplified it is unusually responsive to any level of epidermal growth factor. The increased amount of the gene leads to an increased amount of mRNA and therefore an increased amount of proteins

Question 48

Myc and neuroblastoma

Answer 48

Myc is a transcription factor that turns on 15% of the human genome many of the genes relating to proliferation. the myc gene can become an oncogene due to amplification leading to cancers such as neuroblastoma

Question 49

Does only one gene get amplified in the genome?

Answer 49

no, an entire region of the genome is amplified along and coincidentally there’s an oncogene that can be amplified. Scientists looked at the gene expression of a region on the 17q of a breast tumor genome by using micro array analysis. Not only was the Her2 gene amplified but other genes surrounding the Her2 gene were also amplifed. By amplifying a region multiple issues could arise.

Question 50

Burkitts’ lymphoma

Answer 50

is caused by a reciprocal translocation between chromosome 8 and chromosome 14. The translocation will move the myc gene from chromosome 8 to chromosome 14 right behind an immunoglobulin gene. Therefore causing the myc to be an oncogene. Problems will arise in cells that produce a lot of the immunoglobulin and won’t arise in cells that do not produce a lot of the immunoglobulin. Therefore, an over proliferation of WBC will cause lymphoma or leukemia.

Question 51

Philadelphia chromosome

Answer 51

is caused by a translocation fo the abl gene from chromosome 9 to chromosome 22 placing the abl gene right after a bcr gene such that the bcr open reading frame is not disturbed. This translocation will cuase the abl gene to be an oncogene. This will create a hybrid brc-abl protein. Abl is a protein kinase associated with proliferation. Many different types of leukemia can be attributed to the bcr-abl hybrid protein.

Question 52

Imatinib (Gleevec)

Answer 52

a drug made to sit in the active site of abl so to inhibit just the protein tyrosine kinase action in the hybrid brc-abl protein

Question 53

Kaplan-Meirer plot

Answer 53

shows survivability after diagnosis, it is a standard way to describe survivability and effectiveness of a drug

Question 54

Who and how did they find that cells can be transformed due chemically

Answer 54

Weinberg in 1979 used chemicals to transform a cell. DNA from the foci was then isolated, fragmented randomly using the sheer forces of a syringe, and then transfected into a normal mouse fibroblast. If the chemical caused a gene to alter and transform the cell then that altered gene should be in one of the fragments and therefore should cause transformation in the normal mouse fibroblast. Transformation did occur and a foci was found. They then tried it in vivo within a mouse to see if ti would cause a tumor and it did. Now they knew that cells, that were never exposed to a virus, could be transformed chemically

Question 55

Who and how did they isolate the Ras oncogene from a human tumor

Answer 55

Weinberg They first took a human bladder cancer cell, isolated DNA from it, sheered the DNA randomly, and transfected a mouse cell line. When the foci appeared they extracted DNA, fragmented it, and then put the fragments in phages in order to copy the entire genome. They plated the phages and took an Alu probe to find the phage colony that held only human DNA. Most of the colonies only held mouse DNA but the one colony that had human DNA would hold the gene that caused the mouse cell transformation. They isolated the colony that held the human DNA and determined that it was normally found in the human genome by using a southern blot. They wanted to see what part of oncogene caused the transformation. They took a proto-oncogene copy and the oncogene copy, disassembled the gene and reassembled it in various combinations. They would take each combination and ran a transfection to see if a foci would appear. They narrowed down the region where the proto-oncogene became an oncogene then sanger sequenced both the proto-oncogene version and the oncogene version. They found that it was a missense mutation that caused the transformation. They also discovered that the gene was ras and that the mutation was found in 15-20% of all human tumors.

Question 56

Alu probe

Answer 56

is used due to it being a middle repetitive fraction of human DNA found all throughout the genome

Question 57

How are oncogenes categorized?

Answer 57

based on the proteins that control cell growth

Question 58

What are some categories of oncogenes

Answer 58

growth factors (ex/ platelet derived growth factor amplification due to sis oncogene), growth factor receptors (ex/ tyrosine kinase, RAS), intracellular transducers, transcription factors (ex/ myc), apoptotic proteins (if they are not functioning then the cell will never die), cell cycle control proteins (DNA repair proteins like BRACA)

Question 59

Percivall Pott

Answer 59

was a physician who saw an association between occupation (chimney sweeps) and cancer (scrotal and skin). he found chimney sweeps in london had higher accounts of skin cancer than the chimney sweeps in Denmark because london chimney sweeps did not clean themselves after work while Danish chimney sweeps did.

Question 60

Yamagiwa

Answer 60

found that chemicals could directly cause cancer. he took coal tar from chimneys and painted it inside of a rabbit ear every day and that rabbit ear began to grow tumors

Question 61

Carcinogens

Answer 61

agents that lead to cancer, not all carcinogens are mutagens

Question 62

Testosterone supplements

Answer 62

aid in growth of prostate, an example of a carcinogen that is not a mutagen. if you have a few cancer cells within your prostate the testosterone supplement will lead to cancer cell growth

Question 63

How many mutations must cancer cells accumulate to be malignant

Answer 63

around 4-6

Question 64

Gain of function mutations

Answer 64

found within myc or ras, with myc the gain of function is that we make too much myc, with ras the gain of function is that we cannot turn off ras, the function of the gene isn’t knocked out but rather it is enhanced (when you knock out the function of a gene it is a tumor supressor)

Question 65

What were the discoveries of Rous, Bishop and Varmus, Temin, Baltimore, and Dulbecco, and Weinberg

Answer 65

Rous first discovered RSV in chickens. Temin, Baltimore, and Dulbecco characterized and proving that a virus could have an RNA genome that was converted to DNA using reverse transcriptase. Against central dogma. They looked at the ability of a retrovirus to cause cancer and it did that because on its very first infection it was called ALV and when it left and picked up src gene it became RSV. In viruses rates of mutations are high therefore src gene was mutated to become a v-onc. Bishop and Varmus found that src was a gene for a protein kinase. Weinberg then isolated DNA from human bladder cancer and chopped the DNA up. They cloned the entire genome from the tumor using phages. They then transfected a mouse cell line to see if it would transform. When it did they knew that it was that particular phage held the human gene that caused cancer. They then use an Alu probe to pinpoint the human gene