Chapter 7: Neoplasia Flashcards
What kind of tumor is derived from glands and applied to benign epithelial neoplasms?
Adenoma
What benign epithelial neoplasm has visible finger like or warty projections?
Papilloma
A polyp with glandular tissue is called what?
Adenomatous polyp
Malignant tumors arising from solid mesenchymal tissues are called what?
Sarcoma
Malignant neoplasms of epithelial cell origin, derived from any of the 3 germ layers, are called what?
Carcinomas
What is the most common mixed tumor?
Capable of producing what and is designated?
- Salivary gland mixed tumor
- Epithelial and myoepithelial cells = pleomorphic adenoma
What is the term applied to a heterotopic rest of cells?
i.e., a small nodule of well-developed and normally organized pancreatic tissue found in the submucosa of the stomach, duodenum, or SI.
Choristoma
Lack of differentiation, or anaplasia, is considered a hallmark of?
Malignancy
What refers to variation of size and shape of cancer cells?
Pleomorphism
What best describes carcinoma in situ?
- Dysplastic changes are marked and involve the full thickness of the epithelium
- Lesions DO NOT penetrate the BM
What malignant cancers invade early but rarely metastasize?
- Gliomas
- Basal cell carcinoma of the skin
Once tumor cells breach the basement membrane they are said to be?
Invasive
How is dysplasia related to malignant transformation?
Is all metastatic epithelium dysplastic?
- May be a precursor to malignant transformation
- Does NOT always progress to cancer
- Not all metastatic epithelium is dysplastic
What are the 3 pathways of spread of cancer?
1) Direct seeding of body cavities or surfaces
2) Lymphatic spread
3) Hematogenous spread
In direct seeding of body cavities, sometimes appendiceal carcinomas or ovarian carcinomas fill the peritoneal cavity with what?
Pseudomyxoma peritonei
What is the most common pathway for the initial dissemination of carcinomas?
Lymphatic spread
Where do carcinomas of the breast in the upper outer quadrant disseminate 1st to?
Inner quadrants?
- Axillary LNs
- LNs along internal mammary arteries
Where do carcinomas of the lung in the major respiratory passages metastasize first to?
Perihilar tracheobronchial and mediastinal nodes
Renal cell carcinoma invades what structure?
Renal vein —> IVC —-> right side of the heart (sometimes)
Hepatocellular carcinoma often penetrates what?
Portal and hepatic radicles
Breast carcinoma preferentially spreads to where?
Bone
Bronchogenic carcinoma preferentially spreads to where?
Adrenals and brain
Neuroblastoma preferentially spreads to where?
Liver and bones
To avoid the considerable surgical morbidity associated with full LN dissection, which technique is often used to assess the presence of metastatic lesions in the LNs?
- Biopsy of sentinel nodes
*The first node in a regional lymphatic basin that receives lymph flow from the primary tumor
Which organs are most frequently involved in hematogenous dissemination of cancer?
Liver and lungs
Describe the following for benign cancers:
- Differentiation
- Rate of growth
- Local invasion
- Metastasis
- Well differentiated; structure sometimes typical of tissue of origin
- Progressive and slow growth
- Cohesive, expansile, well-demarcated masses that do not invade
- Absent metastasis
Describe the following for malignant cancers:
- Differentiation
- Rate of growth
- Local invasion
- Metastasis
- Lack differentiation (anaplasia); structure often atypical
- Erratic, slow or rapid growth
- Locally invasive
- Frequent metastasis
Cancers arising in close proximity to the vertebral column often embolize through where?
This pathway is involved in the frequent vertebral metastases of carcinomas of?
- Paravertebral plexus
- Thyroid and prostate
What are the most common tumors in Men?
Woman?
Men = prostate, lung, and colon
Woman = breast, lung and colon
What is responsible for a large majority of cervical carcinoma and increasing fraction of head and neck cancers?
HPV
What cancer is associated with benzene (i.e., light oil, paint, printing, dry cleaning, adhsives. etc.)?
Acute myeloid leukemia
What cancer is associated with beryllium (i.e., missle fuel, space vehicles)?
Lung carcinoma
What cancer is associated with cadmium (i.e., yellow pigments and phosphors; used in batteries, etc.)?
Prostate carcinoma
What cancer is associated with vinyl chloride (i.e., refrigerant, vinyl polymers, plastic adhesives, etc.)?
Hepatic angiosarcoma
What cancer is associated with chromium (i.e., metal alloys, paints, pigments, and preservatives)?
Lung carcinoma
What cancers are associated with nickel?
Lung and oropharyngeal carcinoma
What cancers are associated with Arsenic?
Lung carcinoma
Skin carcinoma
What is the etiologic agent of osteomyelitis?
What neoplasm?
- Bacterial infection
- Carcinoma in draining sinuses
What is the etiologic agent of Chronic Cystitis?
What neoplasm?
- Schistosomiasis
- Bladder carcinoma
What is the associated neoplasm of Sjorgen syndrome and Hashimoto thyroiditis?
MALT lymphoma
What is the classic example of a benign, neoplastic, precursor lesion?
Colonic villous adenoma
What are 2 examples of epigenetic modifications that contribute to the malignant properties of cancer cells?
1) DNA methylation: silencing of tumor suppressor genes
2) Histone modification
What are the 4 classes of regulatory genes that are principal targets of cancer-causing mutations?
1) Growth-promotong proto-oncogenes
2) Growth-inhibiting tumor suppressor genes
3) Genes that regulate apoptosis
4) DNA-repair genes
What are the 8 fundamental changes in cell physiology, which are considered the hallmarks of cancer?
1) Self-sufficiency in growth signals
2) Insensitivity to growth-inhibitory signals
3) Altered cellular metabolism
4) Evasion of apoptosis
5) Limitless replicative potential (immortality?)
6) Sustained angiogenesis
7) Ability to invade and metastasize
8) Ability to evade host immune response
Define Oncoprotein
A protein encoded by an oncogene that drives increased cell proliferation through one of several mechanisms
What is MYC known as and what are its important functions?
- The master transcription factor that regulates genes needed for rapid cell growth by deregulation through chromosomal translocations
90% of what type of cancer contains RAS mutations?
Pancreatic adenocarcinomas
What is the major function of CDK4; D cyclins?
Form a complex that phosphorylates RB, allowing the cell to progress through the G1 restriction point
What is the major function of the cell cycle component, RB?
- Tumor suppressive “pocket” protein that binds E2F transcription factors in its hypophosophorylated state, prevents G1/S transition
- Interacts with several transcription factors that regulate differentiation
What induces the cell cycle inhibitor p21?
p21 is induced by tumor suppressor p53
What responds to growth suppressors such as TGF-B?
p27
What chromosome is p53 located on?
Acts mainly through what?
What negatively regulates p53?
- Chromosome 17
- Acts mainly through p21
- Negatively regulated by MDM2
What inhibits MDM2 activity?
What does this do?
- p14
- Increases p53 activity
What specifically binds to cyclinD-CDK4, blocking CDK4/cyclin D-mediated phosphorylation of RB; thereby reinforcing the RB checkpoint?
p16
What occurs in the familial form of retinoblastoma?
Inherited how?
- All somatic cells inherit one mutated copy of RB gene from a carrier parent (first hit)
- Only one additional RB mutation in a retinal cell is required for complete loss of RB function (second hit)
- Autosomal dominant
What occurs in sporadic cases of Retinoblastoma?
- Both normal RB alleles must undergo somatic mutation in the same retinoblast (two hits)
- Probability of this event is low (explaining why this tumor is uncommon in th general population)
What is the “two-hit” hypothesis of oncogenesis as it relates to retinoblastoma?
Which chromosome involved?
- Two mutations (hits) involving both alleles of RB at chromosome locus 13q14 are required to produce retinoblastoma
- In familial cases, children inherit one defective copy of the RB gene in the germline (first hit), and the other copy is normal. Retinoblastoma develops when the normal RB allele is mutated in retinoblasts as a result of spontaneous somatic mutation (second hit)
What are the key initiators of p53 activity following DNA damage or cellular exposure to hypoxia?
How do they act; what is p53 released from?
- ATM/ATR family
- These kinases phosphorylate p53, liberating it from inhibitors such as MDM2
What affect does the active hypophosphorylated RB in complex with E2F transcription factors have?
- Binds DNA, recruits chromatin-remodeling factors (histone deacetylases and histone methyltransferases)
- Inhibits transcription of genes who products are required for the S phase of the cell cycle
What phosphorylates RB (inactivating it)?
What occurs when RB is phosphorylated?
- Phosphorylated by cyclin D-CDK4 and CDK6; also cyclin E-CDK2
- Causes RB to release E2F
- E2F is then able to activate transcription of S-phase genes
Virtually all cancer cells show dysregulation of the G1-S checkpoint as a result of mutation in one of four genes that regulate the phosphorylation of RB; what are these genes?
- RB (loss of function mutations)
- CDK4 (gene amplifications)
- -* Genes encoding cyclin D proteins (gene amplifications)
- CDKN2A (p16): loss of cyclin-dependent kinase inhibitors
Which GFs activate Cyclins D/CDK4,6 and Cyclin E/CDK2 leading to hyperphosphorylated RB (inactive)?
EGF and PDGF
Explain the interaction between the E7 protein of HPV and RB, where does it bind?
Which form of HPV is higher risk and why?
- Binds to hypophosphorylated form of RB in the same pocket which normally sequesters E2F transcription factors
- HPV16 confers a high risk for development of cervical carcinoma and expresses E7 protein variants with higher affinity for RB than do lower risk viral types
- RB protein is unable to bind E2F transcription factors and is functionally inactivated by these viral oncoproteins, and the E2F factors are free to cause cell cycle progression
Normal GF signaling leads to RB _______ and __________, thus promoting cell cycle progression
Normal GF signaling leads to RB hyperphosphorylation and inactivation, thus promoting cell cycle progression
Tumors with wild type or mutated TP53 alleles are more susceptible to chemotherapy?
What kind of cancers?
- Wildtype
- Testicular Teratocarcinomas and Childhood Acute Lymphoblastic Leukemia
Activation of normal p53 by DNA-damaging agents or by hypoxia leads to cell cycle arrest in which phase?
Causes induction of DNA repair by transcriptional upregulation of what?
- Arrest in G1
- Upregulation of cyclin-dependent kinase inhibitor, CDKN1A (encoding p21): inhibitor of CDK4/D cyclin
- Upregulation of GADD45 genes (DNA repair)
If DNA repair fails, what does p53 trigger?
- Apoptosis (through BAX and PUMA)
- Senescence
Mutated TP53 alleles are mostly resistant to chemotherapy and irradiation and include what cancers?
Lung and colorectal cancers
What do cells with defective p53 acquire and what does this result in?
- Mutator phenotype
- Tendency to acquire additional mutations at a higher rate
Rare patients with Li-Fraumeni syndrome inherit how many defective copies of TP53?
Inherit one defective copy of TP53 and have a very high incidence of a wide variety of cancers
The majority of human cancers demonstrate ________ mutations in TP53
The majority of human cancers demonstrate biallelic loss-of-function mutations in TP53
Like RB, p53 can also be inactivated by?
Viral oncoproteins, such as the E6 protein of HPV
What is the “gatekeeper of colonic neoplasia?”
Functions by?
- Adenomatous polyposis coli (APC)
- Downregulates growth-promoting signaling pathways
Germline loss-of-function mutations involving APC (5q21) locus are associated with what disorder?
Inheritance pattern?
- Familial Adenomatous Polyposis = Autosomal Dominant
- Individuals born w/ one mutant allele develop thousands of adenomatous polyps in the colon during their teens or 20s
What is the role of APC in regulating the stability and function of β-catenin in both resting and WNT activated colonic epithelial cells?
Forms what?
What does β-catenin do?
- In resting colonic epithelial cells (not exposed to WNT), β-catenin forms macromolecular complex containing the APC protein. This complex leads to destruction of β-catenin, and intracellular levles are low
- When stimulated by WNT, the destruction complex is deactivated, β-catenin degradation does not occur, and cytoplasmic levels increase
- β-catenin translocates to the nucleus, where it binds to TCF, a TF that activates genes involved in cell cycle progression and proliferation