Cancer Flashcards
Chondro-
cartilage
Leiomyo-
smooth muscle
Rhabdomyo-
Skeletal muscle
seminoma
germ cell (testicular)
teratoma
germ cell (multiple layers)
Contrast gross pathology, histopathology, and cytopathology
gross - findings from naked eye examination of specimens
histopathology - findings from microscopic examination of stained tissue
cytopathology - findings from the microscopic examination of individual cells or groups of cells
Define molecular pathology
findings from the examination of the DNA/RNA of specimens
Contrast general gross characteristics of benign and malignant tumors.
Benign - smooth, well circumscribed border
sometimes are encapsulated by fibers
Malignant - irregular, diffuse and invasive borders
What are some key microscopic features of malignant tumors?
Nuclear irregularities, such as:
- Irregular contours
- Increased size (high nucleus to cytoplasm ratio)
- Large and/or multiple nucleoli
- Open chromatin or hyperchromasia (dark from abundance of chromatin)
- Areas of necrosis (lack of blood supply)
What characteristics factor into tumor grading?
low-grade: well-differentiated cells (look like cell of origin)
High-grade: poorly differentiated (looks less like cell of origin) or undifferentiated (anaplastic)
What are three avenues for metastasis?
Hematogenously - blood vessels
Lymphatic - lymph (can invade nerves)
Transcoelemic - through body cavities
What are paraneoplastic syndomes and list a few common examples
Distant affects of malignant tumors
Cachexia (wasting)
Hypercalcemia (abundance of calcium)
Polycethemia (abnormally high Hbg)
adeno-
glands
Stage
T: Tumor Size/Extent
N: Nodal
M: Metastasis
Oncogenes
“Accelerators”
Normal genes that when mutated accelerate cell proliferation
- Amplification, alters transcription factors, promoter demethylation, miRNA overexpression
KRAS
Common in colon cancer
GTPase, mutations can result in inappropriate activation (oncogene)
HER2
Common in breast cancer
Amplification of activity leads to increased signalling for cell proliferation (oncogene)
receptive to Herceptin
Tumor Supressor Gene
“Brakes”
Genes that when mutated to be less active can lead to cancer
- Deletion, Alters transcription factos , promoter methylation, miRNA underexpression
RB
(Retinoblastoma) Tumor Suppressor Gene
Inactivating mutation doesn’t allow for Rb to inhibit the cell cycle
TP53
Tumor Suppressor
Deletion -> No protein, affected restriction point in cell cycle
Hallmark 1
Cancer Cells avoid Apoptosis
Overexpression of BCL2
Inhibits mitochondrial response to damage and lack of growth signals
Hallmark 2
Cancer cells use growth signaling pathways (autocrine)
Amplification of HER2 growth factor signalling, results in active GTPase
Hallmark 3
Cancer cells escape tumor suppression
Mutations that result in hyperphosphorylation of Rb (no inhibition of transcription factors) can cause cancer
Hallmark 4
Tumors grow their own blood supply
Vascular endothelial growth factor (VEGF) induce blood vessel formation
Hallmark 5
Cancer cells divide without end
Mutations for high telomerase activity
Hallmark 6
Cancer cells invade and spread Loss of E-Cadherins allow cancer cells to break apart from each other Matrix Metalloproteinases (MMP) breakdown of basement membrane
Chronic Myelogenous Leukemia (CML)
- BCR-ABL gene, balance 9:22 translocation (fusion gene)
- codes a tyrosine kinase that is always on
- Treated with imatinib (tyrosine kinase inhibitor)
What Chemicals can cause cancer?
- Aflatoxin: reactive metabolite causing DNA damage (Hepatocellular carcinoma)
- Asbestos: (mesothelioma)
- Cigarrette Smoke: (3,4-benzyprene) reactive metabolite, obviously lung cancer
- Radiation (ionizing): mutations, genome level breakage (leukemia and thyroid)
- Sunlight (UV light): T-T dimers (carcinoma&melanomas)
Human Papillomavirus (HPV)
- VIruses can cause cancer
- sex transmitted,
- HPV proteins E6 binds p53
- E7 binds Rb
Also Human-Herpes Virus 8 (HHV-8)
Epstein-Barr Virus (EBV)
Hepatitis B (HBV) and Hepatitis C (HCV)
Adeno-Carcinoma Sequence
-Colorectal Carcinoma development
Normal Epithelium –(APC)–> Adenoma –
–(KRAS)–>–(Tp53)–> Carcinoma
Familial Adenomas Polyposis (FAP)
Defects in mismatch repair genes leading to colonic adenocarcinoma
- colon carpeted w/ polyps
- auto dominant 100% chance after 50 years
Hereditary NonPolyposis
- Colon Cancer from a germline mutation of mismatch repair genes
- Rare Auto dominant (Mutations of MLH1, MSH2, MSH6, PMS2)
Unlike FAP, characterized by just a few polyps
Li-Fraumeni Syndrome
Mutation of p53
Neurofibromatosis
Mutation of NF1
BRAF
Mutation->melanoma - Downstream of KRAS
Cell Surface receptor -> Ras -> BRAF -> Cell Proliferation
BRAF Kinase Inhibitor (medication)
MircoRNAs
- Don’t code for anything (down regulate gene expression)
- Can be tissue specific
- Form RISC complex on mRNA which suppresses translation
- Can act as oncogenes and tumor supressors
Cancer drugs that target cell cycle machinery
Antimetabolites, microtubule targeting drugs, topoisomerase II inhibitors
Methotrexate
folic acid analog, inhibits dihydrofolate reductase
decreased Met synthesis
slow DNA/RNA/protein synthesis
Metcaptopurine
Thiopurine prodrug, needs activation
induces mutations and inhibits de novo purine synth.
Fluoruracil
inhibits thymidylate synthetase
dUMP–X–>dTMP
Cytarabine
cytosine analog
blocks DNA/RNA polymerases
Gemcitabine
cytosine analog
blocks DNA synth.
Vinca alkaloids
bind tubulin, inhibit spindle formation
eg. Vinblastine / Vincristine
Taxoids
induce polymerization of microtubes
arrest cell cycle
eg. Taxol/Paclitaxel
Epipodophyllotoxins
dsDNA breaks
eg. Etoposide
Alkylating agents
irreversible changes in DNA (cross-linking)
has unwanted effects, also alters RNA and proteins
eg. Cyclophosphamide (nitrogen mustard)
Antitumor antibiotics
intercalate into DNA, inhibit transcription
eg. Doxorubicin / adriamycin
Camptothecins
bind to DNA topoisomerase I
ssDNA breaks
eg. Irinotecan, topotecan
Platinum compounds
induce DNA crosslinks
eg. Cisplatin / Carboplatin
Tamoxifen
anti-estrogen
used for breast cancer
Enzalutamide
anti-androgen
used for prostate cancer
Lentrozole
prevents estrogen receptor activation
testosterone –X–> estradiol
Abiraterone
inhibits androgen synthesis
Combination chemotherapy
Cycle chemo. drugs 2-4 weeks
Benefits:
-Have different mech’s of action/resistance
-Side affects often wear off by week 4
Log-kill hypothesis
drug kills a constant function of cells
drugs must be given frequently but not too frequently
-too often = sever illness
-too little = cancer growth>death