What is Biology Good For?
Killing Cancer Cells: Chemotherapy Drugs
(This assignment is
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bottom for 3 extra credit points. It is not necessary to
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Common Chemotherapy Drugs
Most chemo drugs are known as
neoplastics being cancer cells. Most antineoplastics work by stopping
cell division in one or another stage of the cell cycle.
They cause cell death in any dividing cell, and since most
human cells are not dividing all the time, they
preferentially kill cancer cells. But any human cell types
which divide frequently are also killed: cells in the
gastrointestional tract, the bone marrow, and hair follicles.
These are reversible processes and will symptoms will
disappear when the drug is discontinued. (But the cancer
cells will be hopefully killed by then). [Quote]
The most common drugs used for newly
diagnosed cancer are Cyclophosphamide (Cytoxan),
Methotrexate, 5-Fluorouracil (5-FU) and Doxorubicin
(Adriamycin). These are often given in combination: CMF
- which stands for Cytoxan, Methotrexate and 5-Fluorouracil, AC
- for Adriamycin and Cytoxan, or CAF (or FAC) -
Cytoxan, Adriamycin, and 5-Fluorouracil.
Generic Name: Doxorubicin
Mode of Action: Adriamycin prevents DNA replication. The exact mechanism is still being studied, but it
may be a "topoisomerase inhibitor". Topoisomerases
are enzymes that temporarily cut one strand of DNA during
replication to help unwind the double helix.. Adriamycin
prevents the topoisomerase from reattaching the cut ends. A
new version of doxorubicin 'wrapped up' in a lipid coat
(liposome) called Doxil has been recently approved as
a Kaposi's sarcoma treatment.
Common Side Effects: hair loss,
mouth sores, nausea, vomiting, lowered blood counts (WBCs,
RBCs and platelets), damage to the heart muscle, skin damage
if drug leaks out of vein during infusion.
Generic Name: Cyclophosphamide
Mode of Action: Interferes with DNA synthesis and replication. Cytoxan is a drug that cross-links with the
nucleotides of DNA. When cross-linked with Cytoxan, the DNA
double helix is unable to unwind, DNA replication does not
occur, and the cells die.
Common side effects: Cytoxan is one
of the nastier chemo drugs, with lots of side effects. Side
effects include lowered blood counts (WBCs, Platelets, RBCs),
nausea, vomiting, loss of appetite, hair loss, loss of
menstrual periods, decreased sex drive, bladder irritation,
metallic taste in mouth during injection.
5FU or Adrucil
Generic Name: 5-Fluorouracil
Mode of Action: Stops DNA synthesis and
replication by inhibiting the
enzyme thymidylate synthetase, involved in the incorporation
of the nucleotide T into the DNA during replication.
Common Side Effects: mild nausea,
vomiting, loss of appetite, thinning or loss of hair, skin
rash and itching, skin darkening, weakness.
Mexate, Emtexate, Metatrexan, Methopterin, or
Generic Name: Methotrexate
Mode of Action: Blocks actively dividing cells
from making nucleotides.
Methotrexate competes in the cell for an enzyme called folic
acid reductase, and prevents the synthesis of
tetrahydrofolate, a chemical used by the cell for making
nucleotides. Without nucleotides, DNA synthesis cannot
Common side effects: mouth sores,
nausea, vomiting, loss of appetite, upset stomach, skin and
eye sensitivity to sunlight, abnormal liver function tests,
hair loss, anemia.
Generic Name: Paclitaxel
Mode of Action: Taxol
(Paclitaxel) was first isolated from the from the bark of the
Pacific Yew tree (Taxus brevifolia). Taxol disrupts the balance
between tubulin and microtubule fibers, causing the formation of abnormal microtubule
bundles. This prevents dividing cells from moving chromosomes
to their "daughter" cells by interfering with
spindle fiber formation.
Common side effects: Allergic
reaction such as low blood pressure, shortness of breath,
rash; loss of hair; low blood cell counts; nerve pain.
Vincasar, Vincrex, or Leurocristine
Generic Name: Vincristine
Mode of Action: Prevents
the formation of spindle fibers during metaphase of mitosis. Vincristine is an alkaloid isolated from
the Madagascar periwinkle, Catharantus roseus, formerly
classified as Vinca rosea, which led to it being called a
Vinca alkaloid, and thus vincristine. It binds to tubulin,
the protein that makes up the spindle fiber microtubules, and
prevents metaphase of mitosis.
Common side effects: bloating,
nausea and vomiting, skin rash, temporary loss of hair,
Leukerin, Mercaleukin, or Puri-Nethol
Generic Name: 6-Mercaptopurine,
Mode of Action: Inhibits the synthesis of the
purine nucleotides A and G
necessary for DNA synthesis; may also mimic A and G during
DNA replication and stop further DNA synthesis.
Common side effects:low blood
counts, mouth sores, skin rash/acne, mild nausea, abnormal
Ara-C, Arabitin, Aracytine, Cytarbel, or Cytosar
Generic Name: Cytosine arabinoside
Mode of Action: Ara-C is a DNA synthesis
inhibitor. Its structure is very
similar to the nucleotide C, but instead of having a ribose
(for RNA) or a deoxyribose (for DNA) sugar, its consists of
an arabinose sugar - a 5 carbon sugar that competes for the
enzymes in DNA synthesis, but cannot function in DNA or RNA.
Common Side effects: decreased blood
counts with risk of infection, bleeding and anemia which may
require blood transfusion, nausea and diarrhea, abdominal
pains, mouth sores, liver injury (which gets better after the
drug is stopped).
For Further Information, see:
Breast Cancer Decision Guide
Questions: 3 points extra credit. Click
on the links for more information! One sentence should be
enough to answer each question . Once you hit 'submit', you
will receive a Thank You confirmation page.
Please type your Student
LAST name followed
by first initial or first name:
1. Aside from Chemotherapy, list at least two
available to stop the spread of cancer, breast cancer or
2. What is leukemia and why would it be treated with
chemotherapy rather than other methods?
3. Tumors metastisize when they attract new blood vessel
growth (angiogenesis) and escape to other parts of the body
via the new blood vessel. Why might drugs called angiogenesis inhibitors be useful in stopping the spread of cancer
(you don't need to visit the link unless you want to - just
think about this one!)