Exam 5

carcinoma

cancer of epithelial origin

sarcomas

cancers of connective tissue origin

hyperplasia

excessive number of normal cells

dysplasia

disordered growth and disordered architecture

anaplasia

lacks differentiated characteristics of an identifiable tissue-of-origin

major malignant tumors in adults

1. carcinomas

2. lymphomas

3. leukemias

major malignant tumors in children

1. leukemias

2. brain and CNS tumors

3. lymphoma

familial melanoma

aggressive with poor prognosis

mutation of CDKN2A

sporadic melanoma

aggressive with poor prognosis

mutation of BRAF

basal cell carcinoma

originates from basal layer

most common

rarely metastasizes

good prognosis

inactivation of PTCH (gorlin’s syndrome)

Squamous cell carcinoma

arises from keratinocytes

can metastasize

chemical exposure and tobacco

inactivation of p53

small cell carcinoma

metastatic

sensitive to chemo

can secrete ACTH (Cushing’s)

mutation of p53 and Rb

associated with smoking

non-small cell carcinoma

not metastatic

not sensitive to chemo

includes:

-squamous cell carcinoma

-adenocarcinoma of lungs (non-smokers)

-large cell carcinoma

most common lung cancer in non-smokers

adenocarcinoma

HER2/Neu

gain of function mutation forms oncogene

sporadic breast cancer (ERBB2)

mutations associated with sporadic breast cancer

ERBB2

HER2/Neu

detected by FISH

mutations associated with hereditary breast cancer/ ovarian cancer

Brca1/2

Myc

gene amplification can cause gain of function mutation into an oncogene

upregulates cyclins

downregulates p21 and Bcl2

3 types

-C-myc

-N-myc

-L-myc

C-myc

expressed in most rapidly proliferating cells

N-myc

expressed in pre-B cells, kidney, brain, and intestine

L-myc

expressed during embryogenesis in kidney and lung

Burkitt’s Lymphoma

chromosomal rearrangement cause gain of function mutation and oncogene

chromosomal translocations t8;14

-results in fusion of heavy chain immunoglobulin gene w/ oncogene myc

leads to lymphoma in B lymphocytes

BCR-ABL

chromosome rearrangement → gain of function → oncogene

philadelphia chromosome (t9;22)

hallmark of chronic myelogenous leukemia (CML)

chromosome rearrangement

burkitt’s lymphoma

BCR-ABL

chronic myelogenous leukemia (CML)

Philadelphia chromosome

BCR-ABL

gatekeeper vs caretaker tumor supressors

gatekeeper- controls cell growth (p53)

caretaker- protects integrity of genome

oncomirs

MicroRNAs that regulate expression of tumor suppressors or oncogenes

-loss of tumor suppressor ones allow overexpression of oncogenes

-overexpression of tumor suppressor ones promote tumor progression

sporadic cancers

accumulation of genetic mutations over time

-not inherited

-most cancers are

-can be passed on if mutation is in a germ cell

familial cancers

cancers that run in families

inherited susceptibility and environmental factors

inherited (hereditary) cancers

genetic mutations passed from one generation to the next

least common type

early age of onset

multiple primary cancers in one individual

Tp53 (Li-Fraumeni syndrome)

VHL (Von Hippel-Lindau syndrome)

BRCA1/2 (hereditary breast-ovarian cancer syndrome)

MLH1/MSH2 (lynch syndrome)

APC (familial adenomatous polyposis)

RB1 (retinoblastoma)

NF1 (neurofibromatosis)

MEN1 and RET (multiple endocrine neoplasia type I and II)

Li Fraumeni syndrome

Tp53 (tumor supressor)

brain, breast, leukemia, etc.

hereditary

Von Hippel-Lindau syndrome

VHL

highly vascularized tumors in eye, brain, kidney, etc.

hereditary

hereditary breast-ovarian cancer syndrome

BRCA1/2

Lynch syndrome

AKA hereditary nonpolyposis colon cancer

MLH1/MSH2 (encodes proteins involved in mismatch repair)

-RER+ phenotype

predisposes individuals to colon and endometrial cancers

hereditary

familial adenomatous polyposis

APC mutation → cannot inhibit beta catenin → overexpression of genes (ex. Myc)

prediposes individuals to colorectal cancer

retinoblastoma

cancer of retina

RB1

hereditary

neurofibromatosis

NF1

hereditary

multiple endocrine neoplasia type I and II

Type 1: MEN1 (tumor supressor for cell proliferation genes)

Type 2: RET (receptor tyrosine kinase oncogene)

hereditary

Nucleic acid techinques

agarose gel electrophoresis

PCR

PCR-based diagnostic testing

RFLP

DNA fingerprinting

DNA cloning

fluorescent proteins (FISH)

agarose gel electrophoresis

separation of DNA fragments based on size

migration of DNA through gel is mediated by electrical current

• - charge at top

• + charge at bottom

smaller fragments move faster than larger ones

PCR

amplification of a specific sequence of DNA

comprised of:

• DNA template (sequence to be amplified)

• DNA polymerase (needs to be heat stable)

• pool of dNTPs

• primers

• buffer

PCR based diagnostic testing

tests for presence of an infectious agent

very low level of infection can be detected

RFLP

mutation in recognition site for a restriction enzyme

generated DNA fragments will be a different length from those without the mutation

diagnostic for Sickle Cell anemia

uses southern blotting technique

DNA fingerprinting

highly variable regions (regions of DNA repeated in tandem a variable number of times)

each individual has a different pattern other than twins

DNA cloning

amplification of a specific piece of DNA

• piece of DNA attached to a vector

• cut with restriction enzyme

• forms chimeric plasmid

• introduced to bacterial cells

• allows for amplification of plasmid

Fluorescent proteins

green fluorescent protein allows for visualization of cellular structures in living cells

nucleic acid probes

Fluorescence in situ hybridization (FISH)

Southern blot

method for detecting specific sequences of DNA

• identifies genetic diseases with known mutations

• Ex. sickle cell

northern blot

method for detecting specific sequences of RNA

Sanger method

chain termination sequencing

DNA polymerase incorperates a ddNTP

ddNTP placement is random, creating varying fragments

read bottom to top

protein techniques

PAGE

Western blot

ELISA

Southwestern blot

microarray

proteomics

gene therapy

PAGE

allows separation of proteins based on size

migration of protein through polyacrylamide gel

-mediated by electrical current

western blot

detects a specific protein in a sample

involves a probe with antibodies

can be diagnostic

• Ex. HIV antibody test (HIV positive blood will have an antibody that recognizes viral proteins)

ELISA

sensitive

detects presence of a molecule

fast results

Ex. rapid antibody test for HIV (ay have false positives or negatives, follow up with a western blot)

southwestern blot

identifies protein-DNA interactions

microarray

used to compare gene expression patterns between cells exposed to 2 different conditions or between a health and diseased cell

proteomics

compares differences in expression of proteins between 2 samples

gene therapy

introduces normal copies of defective genes

characteristics of cancer

immortal

• continuous cell growth and limitless replication

persistent proliferation

inactivation of anti-proliferative signals

resistance to cell death

angiogenesis

metastasis

replicative capacity

somatic cells have a predetermined number of cell divisions

2 mechanisms govern:

• senescence (p21)

• telomere length (short die)

telomeres

found at end of chromosomes

synthesized by telomerase

somatic cells can be converted to cancer cells through telomerase activation

oncogenes

gain of function mutation of a proto-oncgene

dominant

Ras → Raf → Mek → Erk

tumor supressors

control cell progression

• p53

• Rb

• p21

recessive

2-hit model

2nd hit loses heterozygosity

p53

WNL degraded by Mdm2

Mdm2 inactivates with cellular stress

p53 accumulates and cell dies

p21

increased by cell stress or DNA damage

inhibits Cdk proteins

Rb

inhibits E2F (prevents G1 → S)

apoptosis

programmed cell death

p53

3 ways

• induces expression of genes encoding Fas receptor

• induces expression of IGF-binding protein-3

• induces expression of Bax

  • pro-apoptotic protein, causes release of cytochrome C from mitochondria

Metastasis phases

invasion of extracellular matrix

• dissociation of cells from one another

  • down-regulation of cadherins

• degradation of basement membranes

  • secrete collagenases

• changes in attachment of tumor cells to ECM proteins

• locomotion (move through basement membrane)

vascular dissemination and homing (aggregate in clumps with T lymphocytes)

Humam papilloma virus (HPV)

DNA virus that integrates into genome

E6 binds to p53 causing ubiquination and degradation of p53

E7 binds to Rb preventing its inhibition of E2F

gene therapy in retroviruses

retroviruses- RNA viruses that use reverse transcriptase to make double stranded DNA copy of RNA genome

can stably integrate into cells nuclear DNA (therapy is essentially permanent)

cons:

• integration site is random (problems if integration area disrupts a gene or causes gene overexpression)

• can only infect dividing cells

gene therapy in adenoviruses

adenovirus- DNA virus that do not integrate into cell’s genome

can carry larger genes than retroviruses

can infect dividing and non-dividing cells

cons:

• do not integrate into genome