Aspirin reduces cancer
risk through promoting death of abnormal cells (apoptosis) and through effect
upon prostaglandins (COX-1 & COX-2).
. Overexpression of
cyclooxygenase-2 (COX-2)
and increased prostaglandin biosynthesis correlates with carcinogenesis and
metastasis at most anatomic sites.
Several mechanism for promoting death of abnormal cells have been found
including the activiation of NF-B
signaling pathway We analyzed the effect of aspirin, salicylate, and other nonsteroidal
antiinflammatory drugs (NSAIDs) on the viability of B-chronic lymphocytic
leukemia (B-CLL) cells. Aspirin induced a decrease in cell viability in a dose-
and time-dependent manner. The mean IC50 for cells from 5 patients
was 5.9 ± 1.13 mmol/L (range, 4.4 to 7.3 mmol/L). In some cases, 2.5 mmol/L
aspirin produced an important cytotoxic effect after 4 days of incubation. No effect was
observed with other NSAIDs, at concentrations that inhibit
cyclooxygenase, such as ketorolac (10 μmol/mL), NS-398 (100 μmol/mL), or
indomethacin (20 μmol/mL), thus suggesting the involvement of
cyclooxygenase-independent mechanisms in aspirin-induced cytotoxicity.
Salicylate also produced dose-dependent cytotoxic effects on B-CLL cells and
the mean IC50 for cells from 5 patients was 6.96 ± 1.13 mmol/L
(range, 5 to 7.8 mmol/L). Both aspirin and salicylate induced DNA fragmentation
and the proteolytic cleavage of poly(ADP(adenosine 5′-diphosphate)-ribose)
polymerase (PARP), demonstrating that both compounds induce apoptosis of B-CLL
cells. Finally, inhibition of caspases by Z-VAD.fmk blocked proteolytic
cleavage of PARP, DNA fragmentation, and cytotoxicity induced by aspirin.
Mononuclear cells from normal donors showed a lower sensitivity than cells from
B-CLL patients to aspirin as determined by analysis of cell viability. B and T
lymphocytes from normal donors and T lymphocytes from CLL patients are more
resistant to aspirin-induced apoptosis, as determined by analysis of
phosphatidylserine exposure. These results indicate that aspirin and salicylate induce
apoptosis of
B-CLL cells by activation of caspases and that this activation involves
cyclooxygenase-independent mechanisms. © 1998 by The American Society of Hematology. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
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Wikipedia aspirin In 1971, British pharmacologist John
Robert Vane, then employed by the Royal College of Surgeons in
London, showed aspirin suppressed the production of prostaglandins
{such as COX-1 and COX-2} and thromboxanes.[114][115] Aspirin reduces the effects of vasopressin[123]
upon the secretion of ACTH
and cortisol
by the hypothalamic-pituitary-adrenal axis
(HPA axis), which has been suggested to occur through an interaction with
endogenous prostaglandins and their role in regulating the HPA axis.[123] Vasopressin is a peptide hormone that controls the reabsorption of
molecules in the tubules of the kidneys by affecting the tissue's permeability. It also
increases peripheral vascular resistance,
which in turn increases arterial blood
pressure. It plays a key role in homeostasis,
and the regulation of water, glucose, and salts in the blood. Aspirin reduces fever and headaches Although aspirin has been used to combat fever and pains
associated with common cold for more than 100 years, its efficacy in
this role was only recently confirmed in controlled clinical trials on adults.
One gram of aspirin, on average, reduced the oral body temperature from 39.0 °C
(102.2 °F) to 37.6 °C (99.7 °F) after three hours. The relief began
after 30 minutes, and after six hours, the temperature still remained below
37.8 °C (100.0 °F). Aspirin also helped with "achiness",
discomfort and headache,[36]
and with sore throat pain, for those who had it.[37]
The effects of aspirin were indistinguishable from those obtained using
paracetamol {acetaminophen, which is toxic to the liver} in any respect, except
for, possibly, a slightly higher incidence of sweating and gastrointestinal
side effects.[36] Fever and joint pain of acute
rheumatic fever respond extremely well, often within three days, to high
doses of aspirin. The therapy usually lasts for one to two weeks; and only in
about 5% of the cases it has to continue for longer than six months. After
fever and pain have subsided, the aspirin treatment is unnecessary, as it does
not decrease the incidence of heart complications and residual rheumatic heart
disease.[38] A 2010 study by Oxford University involving over 25000
patients showed taking a small (75 mg) daily dose of aspirin for between
four and eight years substantially reduces death rates from a range of common
cancers by at least a fifth and the reduction of risk continued for 20 years in
both men and women. For specific cancers the, reduction was about 40% for bowel
cancer, 30% for lung cancer, 10% for prostate
cancer and 60% for oesophageal cancer, while the reductions in pancreas,
stomach,
brain,
breast
and ovarian
cancers were difficult to quantify because there were not enough data, but
other studies are in progress. However, taking aspirin doubles the annual risk
of major internal bleeding that normally has a very low incidence (about 1 in
1000) in middle age, but increased dramatically after 75 years old.[68] · ^ "Small
daily aspirin dose 'cuts cancer risk". BBC News Health (2010),
available at http://www.bbc.co.uk/news/health-11930988 Dosage Adult aspirin tablets are produced in standardised sizes,
which vary slightly from country to country, for example 300 mg in Britain
and 325 mg in the USA. Smaller doses are based on these standards; thus,
75- and 81-milligram tablets are used; there is no medical significance in the
slight difference. It is of historical interest that the US 325 mg dose is
almost exactly equivalent to the historic 5 grain
aspirin tablet that preceded the metric dosage. Wikipedia
prostaglandin A prostaglandin is any member of a group of lipid compounds that
are derived enzymatically from fatty acids and have important functions in the animal body. Every prostaglandin contains 20 carbon atoms,
including a 5-carbon ring. They are mediators and have a variety of strong physiological
effects, such as regulating the contraction and relaxation of smooth muscle
tissue.[1]
Prostaglandins are not hormones, but autocrine or paracrine,
which are locally acting messenger molecules. They differ from hormones in that
they are not produced at a discrete site but in many places throughout the
human body. Also, their target cells are present in the immediate vicinity of
the site of their secretion (of which there are many). The prostaglandins, together with the thromboxanes
and prostacyclins,
form the prostanoid
class of fatty acid derivatives, a subclass of eicosanoids. The diversity of receptors means that prostaglandins act on an array of
cells and have a wide variety of effects such as: Wikipedia
Thromboxane Thromboxane is a member of the family of lipids known as eicosanoids.
The two major thromboxanes are thromboxane
A2 and thromboxane B2. The distinguishing feature of
thromboxanes is a 6-membered ether-containing ring. Thromboxane is named for its role in clot formation (thrombosis).
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