# Aspirin Has Antitumor Effects via Expression of Calpain Gene in Cervical Cancer Cells

Authors: Sang Koo Lee; Min Seon Park; Myeong Jin Nam
Journal: Journal of Oncology
 (2008)

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## Abstract

Aspirin and other nonsteroidal anti-inflammatory drugs show efficacy in the prevention of cancers. It is known that they can inhibit cyclooxygenases, and some studies have shown that they can induce apoptosis. Our objective in this study was to investigate the mechanism by which aspirin exerts its apoptosis effects in human cervical cancer HeLa cells. The effect of aspirin on the gene expression was studied by differential mRNA display RT-PCR. Among the isolated genes, mu-type calpain gene was upregulated by aspirin treatment. To examine whether calpain mediates the antitumor effects, HeLa cells were stably transfected with the mammalian expression vector pCR3.1 containing mu-type calpain cDNA (pCRCAL/HeLa), and tumor formations were measured in nude mice. When tumor burden was measured by day 49, HeLa cells and pCR/HeLa cells (vector control) produced tumors of 2126mm3 and 1638 mm3, respectively, while pCRCAL/HeLa cells produced markedly smaller tumor of 434 mm3 in volume. The caspase-3 activity was markedly elevated in pCRCAL/HeLa cells. The increased activity levels of caspase-3 in pCRCAL/HeLa cells, in parallel with the decreased tumor formation, suggest a correlation between caspase-3 activity and calpain protein. Therefore, we conclude that aspirin-induced calpain mediates an antitumor effect via caspase-3 in cervical cancer cells.


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## Body

## 1. Introduction

Aspirin
and other agents characterized as nonsteroidal anti-inflammatory drugs (NSAIDs)
are designed primarily to decrease pain and inflammation. The molecular basis
for actions of NSAIDs is believed to be their ability to inhibit cyclooxygenase
(COX) activity and block the production of prostaglandins [1]. Among NSAIDs, aspirin and
sulindac can prevent the development of colon cancer and act as an
anti-inflammatory agent by their inhibition of prostaglandin synthesis [2].Cancer
of the uterine cervix is the second leading cause of death from cancer in women
worldwide and also the most prevalent gynecological malignancy in Korea [3]. We investigated
whether aspirin induced apoptosis in human cervical cancer HeLa cells. To
investigate the mechanism by which aspirin exerts its apoptosis effects, the
effect of aspirin on the gene expression was studied by differential mRNA
display RT-PCR (DD RT-PCR). Employing DD RT-PCR methods, we identified aspirin-responsive
gene and mu-type calpain, which was confirmed by
real-time quantitative PCR.Calpain
is known to possess the proteoglycanase activity in vitro [4]. Calpain is ubiquitous
family of Ca2+-dependent neutral cysteine proteases. The two
isoforms are classified according to their Ca2+ requirements: mu-type
calpain and m-type calpain require micromolar and millimolar concentrations of
Ca2+ for activation, respectively. Growing evidence suggested that
calpain may play a central role in the execution of apoptosis via modulation of
caspase-3 activity in  glucocorticoid-treated and irradiated
thymocytes, neuronal cells exposed to UV, or MCF-7 breast cancer cells treated
with β-lapachone [5–7].Further
progress in cancer prevention would depend on understanding the mechanisms
through which aspirin exerts
molecular action. However, the molecular mechanisms through which aspirin alters colonic tumorigenesis are unknown. In this
report, we describe a potential mechanism by which aspirin induces apoptosis in
human cervical cancer cells. To examine whether mu-type calpain
mediates antitumor effects in HeLa cells, HeLa cells were stably transfected
with mu-type calpain cDNA. Tumor formation and
caspase-3 activity of stably transfected cells were measured in nude mice. In
this paper, we suggest that aspirin has an antitumor effect via the expression
of mu-type calpain gene in cervical cancer cells.


## 2. Methods

### 2.1. Apoptosis Analysis

Human
cervical cancer cells, HeLa, were plated in a 24-well plate at a density of1×104 cells/well and treated with various doses of aspirin. To detect an apoptotic
body, cells were stained with Hoechst 33342 dye and assessed for morphological
signs of apoptosis. The proportion of cells in G0/G1, S, and G2/M was
determined by flow cytometric analysis of DNA content (Becton Dickinson, Peterson, NJ, USA).
Cell suspension was stained with propidium iodide. DNA histograms were analyzed
using CELL QUEST software to evaluate cell cycle compartments.


### 2.2. Differential mRNA Display RT-PCR and Cloning

Total
RNA was extracted from cells with TRizol reagent (Invitrogen, Carlsbad, Calif, USA), following the protocol that was
provided. Cell monolayers were washed with PBS, and 1 mL of TRizol/106 cells with 4 units of RNase inhibitor were added. For each sample, 2 μg of
RNA were treated with DNase l (Roche, Basel, Switzerland) at 37°C for 30 minutes to remove contaminating DNA. One-base-anchored
oligo-dT primers were used to reverse transcribed total RNA into first-strand
cDNA, which were amplified subsequently by PCR using the arbitrary upstream
primers. PCR products were labeled with 2 μCi of α[P32]dCTP (Amersham, Arlington, Ill, USA), and analyzed on a 6%
polyacrylamide-urea gel. The cDNA bands that were unique to control or
aspirin-treated cells were cut out of the gel, eluted, and reamplified by PCR.
The candidate cDNA was cloned into pGEM-T vector (Promega, Madison, WI, USA). Plasmid with insert was
purified and sequenced after performing PCR reactions.


### 2.3. Real-time Quantitative PCR

We relied on
the TaqMan assay (Perkin-Elmer model 7700; Foster City, CA, USA) to quantitate the amount of
calpain mRNA. The forward and reverse primers and the FAM-tagged probe used for
the mu-type calpain gene
in the assay were5′-GGATGTCATTCCGAGACT, 5′-CTCGTAGACCGCGAAG, and
5′-6FAM-TCTGCAACCTCACACCCGAC-TAMRA,
respectively. The forward and reverse primers and FAM-tagged probe used for the
ß-actin gene were 5′-AACTTGAGATGTATGAAGGCTTTTGG,
5′-TTTTTTTTTTTTTTTTTTTTTTTTTTTTTAAG, and
5′-6FAM-CAACTGGTCTCAAGTCAGTGTACAGGTAAGCCCT-TAMRA, respectively. To measure the
relative abundance of the calpain gene in any given RNA sample, the
amplification value derived using the calpain sequence was divided by the
amplification value using the ß-actin sequence.


### 2.4. Transfection of Calpain cDNA and Cell Growth Assay

The mu-type calpain cDNA was retrieved with the
following primers: forward5′-AGGATGTCGGAGGAGA and reverse
5′-CCAGTACACAAGTCCCT. PCR reaction products were cloned into pCR3.1 vector
(Invitrogen). The vector pCR or recombinant pCRCAL was stably transfected into
HeLa cells by liposome. Control, vector-transfected (pCR/HeLa), and
calpain-transfected cells (pCRCAL/HeLa) were counted by the trypan blue
exclusion assay and Coulter counter (Coulter Corporation, FL, USA) for
measuring stably transfected cell growth. Cell number was presented as the mean±S.E. five experiments.


### 2.5. Enzymatic Assay for Caspase-3 Activity

Cells
(1.5×106) were plated in cell culture dishes (100 mm) and allowed to
attach for 48 hours under cell culture conditions. Then the cells were treated and
the activity of caspase-3 was measured using the fluorogenic enzyme substrates,
z-DEVD-AFC (Molecular Probes, Eugene, Ore, USA). Samples were read in a fluorometer equipped with a 400 nm
excitation filter and 505 nm emission filter. Enzyme activity was expressed as
relative fluorescence units/mg of protein. The arbitrary values were presented
as the mean±S.E. five experiments.


### 2.6. Tumorigenicity

Balb/c
nu/nu mice, 4–6 weeks of age,
were acclimated and caged in groups of five. HeLa, pCR/HeLa, and pCRCAL/HeLa
cells (1.5×107) were injected subcutaneously into the right flank of
the nude mouse. The mean tumor diameter was measured by dial caliper, and the
volume was calculated by the formula: volume(mm3)=(squarerootofwidth×length)3. Mean values of five
mice/group ±SEM are shown. The experiment was repeated three times and
performed according to the guidelines of the Animal Experimental Committee,
National Institute of Health, South Korea. Statistical
calculations were performed using the Microsoft Excel 97 program (1998; Microsoft
Co., Redmond ,Wash, USA)
to estimate P-value. The significance level (P-value) is
determined using the Student’s t-test. Probability values <.05 were
considered significant.


## 2.1. Apoptosis Analysis

Human
cervical cancer cells, HeLa, were plated in a 24-well plate at a density of1×104 cells/well and treated with various doses of aspirin. To detect an apoptotic
body, cells were stained with Hoechst 33342 dye and assessed for morphological
signs of apoptosis. The proportion of cells in G0/G1, S, and G2/M was
determined by flow cytometric analysis of DNA content (Becton Dickinson, Peterson, NJ, USA).
Cell suspension was stained with propidium iodide. DNA histograms were analyzed
using CELL QUEST software to evaluate cell cycle compartments.


## 2.2. Differential mRNA Display RT-PCR and Cloning

Total
RNA was extracted from cells with TRizol reagent (Invitrogen, Carlsbad, Calif, USA), following the protocol that was
provided. Cell monolayers were washed with PBS, and 1 mL of TRizol/106 cells with 4 units of RNase inhibitor were added. For each sample, 2 μg of
RNA were treated with DNase l (Roche, Basel, Switzerland) at 37°C for 30 minutes to remove contaminating DNA. One-base-anchored
oligo-dT primers were used to reverse transcribed total RNA into first-strand
cDNA, which were amplified subsequently by PCR using the arbitrary upstream
primers. PCR products were labeled with 2 μCi of α[P32]dCTP (Amersham, Arlington, Ill, USA), and analyzed on a 6%
polyacrylamide-urea gel. The cDNA bands that were unique to control or
aspirin-treated cells were cut out of the gel, eluted, and reamplified by PCR.
The candidate cDNA was cloned into pGEM-T vector (Promega, Madison, WI, USA). Plasmid with insert was
purified and sequenced after performing PCR reactions.


## 2.3. Real-time Quantitative PCR

We relied on
the TaqMan assay (Perkin-Elmer model 7700; Foster City, CA, USA) to quantitate the amount of
calpain mRNA. The forward and reverse primers and the FAM-tagged probe used for
the mu-type calpain gene
in the assay were5′-GGATGTCATTCCGAGACT, 5′-CTCGTAGACCGCGAAG, and
5′-6FAM-TCTGCAACCTCACACCCGAC-TAMRA,
respectively. The forward and reverse primers and FAM-tagged probe used for the
ß-actin gene were 5′-AACTTGAGATGTATGAAGGCTTTTGG,
5′-TTTTTTTTTTTTTTTTTTTTTTTTTTTTTAAG, and
5′-6FAM-CAACTGGTCTCAAGTCAGTGTACAGGTAAGCCCT-TAMRA, respectively. To measure the
relative abundance of the calpain gene in any given RNA sample, the
amplification value derived using the calpain sequence was divided by the
amplification value using the ß-actin sequence.


## 2.4. Transfection of Calpain cDNA and Cell Growth Assay

The mu-type calpain cDNA was retrieved with the
following primers: forward5′-AGGATGTCGGAGGAGA and reverse
5′-CCAGTACACAAGTCCCT. PCR reaction products were cloned into pCR3.1 vector
(Invitrogen). The vector pCR or recombinant pCRCAL was stably transfected into
HeLa cells by liposome. Control, vector-transfected (pCR/HeLa), and
calpain-transfected cells (pCRCAL/HeLa) were counted by the trypan blue
exclusion assay and Coulter counter (Coulter Corporation, FL, USA) for
measuring stably transfected cell growth. Cell number was presented as the mean±S.E. five experiments.


## 2.5. Enzymatic Assay for Caspase-3 Activity

Cells
(1.5×106) were plated in cell culture dishes (100 mm) and allowed to
attach for 48 hours under cell culture conditions. Then the cells were treated and
the activity of caspase-3 was measured using the fluorogenic enzyme substrates,
z-DEVD-AFC (Molecular Probes, Eugene, Ore, USA). Samples were read in a fluorometer equipped with a 400 nm
excitation filter and 505 nm emission filter. Enzyme activity was expressed as
relative fluorescence units/mg of protein. The arbitrary values were presented
as the mean±S.E. five experiments.


## 2.6. Tumorigenicity

Balb/c
nu/nu mice, 4–6 weeks of age,
were acclimated and caged in groups of five. HeLa, pCR/HeLa, and pCRCAL/HeLa
cells (1.5×107) were injected subcutaneously into the right flank of
the nude mouse. The mean tumor diameter was measured by dial caliper, and the
volume was calculated by the formula: volume(mm3)=(squarerootofwidth×length)3. Mean values of five
mice/group ±SEM are shown. The experiment was repeated three times and
performed according to the guidelines of the Animal Experimental Committee,
National Institute of Health, South Korea. Statistical
calculations were performed using the Microsoft Excel 97 program (1998; Microsoft
Co., Redmond ,Wash, USA)
to estimate P-value. The significance level (P-value) is
determined using the Student’s t-test. Probability values <.05 were
considered significant.


## 3. Results

### 3.1. Apoptosis in Aspirin-Treated HeLa Cells

We
performed DNA synthesis assay to study the effects of aspirin on HeLa cells.
HeLa cells were treated in 1, 2, or 3 mM aspirin. Aspirin inhibited growth of cervical
cancer cells in a time- and concentration-dependent manner (data not shown).
HeLa cells were then assessed for apoptosis. Aspirin-induced morphological
changes were evident in a concentration-dependent manner (see Figure1). Cells
treated with aspirin became sparse, long squared, and detached from the dishes. Cell number was also decreased. Apoptotic bodies (indicated by white arrows in
Figure 1) were shown after aspirin treatment. To show apoptosis in the cells
treated with aspirin, flow cytometry analysis was performed. The population of
sub-G1 phase was changed from 1.2 to 18.9% in cells treated with 1 mM aspirin for
48 hours. That of sub-G1 phase at 2 and 3 mM was in the similar range.Morphological
characteristics of HeLa cells after aspirin treatment. (a) Cells were treated
with various concentrations of aspirin and grown for 48 hours. For detection of
apoptotic morphology, cells were stained with Hoechst 33342 dye and assessed
for morphological signs of apoptosis. The right panel (b) shows the enlarged
photograph of apoptotic cells (×40).
(a)(b)


### 3.2. Identification of Calpain Gene in Aspirin-Treated HeLa Cells

After
HeLa cells were treated with aspirin for 48 hours, we performed differential display
RT-PCR and selected differentially expressed genes, which was expressed with
absolute difference between control and aspirin-treated cells. The genes were
identified with DNA sequencing. One of the upregulated genes is mu-type
calpain.
Expression of calpain mRNA was confirmed by real-time quantitative PCR (see Figure2). Calpain gene was highly expressed in aspirin-treated HeLa cells in a
concentration-dependent manner. Calpain gene was upregulated by 4.4, 6, and 8.8
folds in the 1, 2, and 3 mM aspirin-treated HeLa cells, respectively.Figure 2
Real-time quantitative
RT-PCR for calpain gene in aspirin-treated HeLa cells. To measure the relative
abundance of mu-type calpain gene in a given RNA
sample, the amplification value derived using calpain gene was divided by the
amplification value using theβ-actin sequence. *,P<.05 control versus treated group.


### 3.3. Tumorigenicity of Calpain Gene Product

We have
cloned mu-type calpain cDNA into pCR3.1
vector. The vector pCR or recombinant pCRCAL was stably transfected into HeLa
cells (pCR/HeLa cell or pCRCAL/HeLa cell). To assess whether change of cell
biology was caused after gene transfection, we measured cell proliferation.
pCRCAL/HeLa cells appeared to have a markedly different growth pattern compared
with HeLa cells and pCR/HeLa cells (see Figure3(a)). To establish a
relationship between calpain and caspase-3, caspase-3 activities were measured.
As shown in Figure 3(b), caspase-3 activity was elevated in pCRCAL/HeLa cells.
The markedly increased activity levels of caspase-3 in pCRCAL/HeLa cells
suggest a correlation of caspase-3 activity and calpain protein. In investigation
of calpain role in the tumorigenicity, we evaluated tumor progression in nude
mice. 1.5×107 stably transfected cells were subcutaneously
injected into the flank of the mouse. When tumor burden was measured by day 49,
HeLa cells and pCR/HeLa cells produced tumors of 2126±163mm3 and 1638±213mm3, respectively,  while pCRCAL/HeLa cells produced
markedly small tumor of 434±206mm3 in volume (see Figure 3(c)). The
experiment was repeated three times with similar results. Tumor growth was reduced
by calpain gene expression.In
vitro characteristics and tumorigenicity of stably transfected cells. (a) Cell
proliferation. Control (HeLa), vector-transfected (pCR/HeLa), and mu-type
calpain-transfected
cells (pCRCAL/HeLa) were counted by the trypan blue staining and Coulter
counter. (b) Caspase-3 activities. Caspase-3 activities were measured by
analyzing the fluorometric cleavage of substrates, z-DEVD-AFC. RFU, relative
fluorescence units. (c) Groups of five mice each were injected with HeLa,
pCR/HeLa, and pCRCAL/HeLa cells (1.5×107 in 0.1 mL saline)
subcutaneously inducing
solid tumor. The tumor volume was evaluated on the 20th, 34th, 41st, and 49th
day onwards after tumor cell induction. The tumor volume was calculated by the
formula:volume(mm3)=(squarerootofwidth×length)3.
Mean values of five mice/group ±SEM are shown. The experiment was repeated three
times with similar results. *,P<.05 HeLa versus pCRCAL/HeLa.
(a)(b)(c)


## 3.1. Apoptosis in Aspirin-Treated HeLa Cells

We
performed DNA synthesis assay to study the effects of aspirin on HeLa cells.
HeLa cells were treated in 1, 2, or 3 mM aspirin. Aspirin inhibited growth of cervical
cancer cells in a time- and concentration-dependent manner (data not shown).
HeLa cells were then assessed for apoptosis. Aspirin-induced morphological
changes were evident in a concentration-dependent manner (see Figure1). Cells
treated with aspirin became sparse, long squared, and detached from the dishes. Cell number was also decreased. Apoptotic bodies (indicated by white arrows in
Figure 1) were shown after aspirin treatment. To show apoptosis in the cells
treated with aspirin, flow cytometry analysis was performed. The population of
sub-G1 phase was changed from 1.2 to 18.9% in cells treated with 1 mM aspirin for
48 hours. That of sub-G1 phase at 2 and 3 mM was in the similar range.Morphological
characteristics of HeLa cells after aspirin treatment. (a) Cells were treated
with various concentrations of aspirin and grown for 48 hours. For detection of
apoptotic morphology, cells were stained with Hoechst 33342 dye and assessed
for morphological signs of apoptosis. The right panel (b) shows the enlarged
photograph of apoptotic cells (×40).
(a)(b)


## 3.2. Identification of Calpain Gene in Aspirin-Treated HeLa Cells

After
HeLa cells were treated with aspirin for 48 hours, we performed differential display
RT-PCR and selected differentially expressed genes, which was expressed with
absolute difference between control and aspirin-treated cells. The genes were
identified with DNA sequencing. One of the upregulated genes is mu-type
calpain.
Expression of calpain mRNA was confirmed by real-time quantitative PCR (see Figure2). Calpain gene was highly expressed in aspirin-treated HeLa cells in a
concentration-dependent manner. Calpain gene was upregulated by 4.4, 6, and 8.8
folds in the 1, 2, and 3 mM aspirin-treated HeLa cells, respectively.Figure 2
Real-time quantitative
RT-PCR for calpain gene in aspirin-treated HeLa cells. To measure the relative
abundance of mu-type calpain gene in a given RNA
sample, the amplification value derived using calpain gene was divided by the
amplification value using theβ-actin sequence. *,P<.05 control versus treated group.


## 3.3. Tumorigenicity of Calpain Gene Product

We have
cloned mu-type calpain cDNA into pCR3.1
vector. The vector pCR or recombinant pCRCAL was stably transfected into HeLa
cells (pCR/HeLa cell or pCRCAL/HeLa cell). To assess whether change of cell
biology was caused after gene transfection, we measured cell proliferation.
pCRCAL/HeLa cells appeared to have a markedly different growth pattern compared
with HeLa cells and pCR/HeLa cells (see Figure3(a)). To establish a
relationship between calpain and caspase-3, caspase-3 activities were measured.
As shown in Figure 3(b), caspase-3 activity was elevated in pCRCAL/HeLa cells.
The markedly increased activity levels of caspase-3 in pCRCAL/HeLa cells
suggest a correlation of caspase-3 activity and calpain protein. In investigation
of calpain role in the tumorigenicity, we evaluated tumor progression in nude
mice. 1.5×107 stably transfected cells were subcutaneously
injected into the flank of the mouse. When tumor burden was measured by day 49,
HeLa cells and pCR/HeLa cells produced tumors of 2126±163mm3 and 1638±213mm3, respectively,  while pCRCAL/HeLa cells produced
markedly small tumor of 434±206mm3 in volume (see Figure 3(c)). The
experiment was repeated three times with similar results. Tumor growth was reduced
by calpain gene expression.In
vitro characteristics and tumorigenicity of stably transfected cells. (a) Cell
proliferation. Control (HeLa), vector-transfected (pCR/HeLa), and mu-type
calpain-transfected
cells (pCRCAL/HeLa) were counted by the trypan blue staining and Coulter
counter. (b) Caspase-3 activities. Caspase-3 activities were measured by
analyzing the fluorometric cleavage of substrates, z-DEVD-AFC. RFU, relative
fluorescence units. (c) Groups of five mice each were injected with HeLa,
pCR/HeLa, and pCRCAL/HeLa cells (1.5×107 in 0.1 mL saline)
subcutaneously inducing
solid tumor. The tumor volume was evaluated on the 20th, 34th, 41st, and 49th
day onwards after tumor cell induction. The tumor volume was calculated by the
formula:volume(mm3)=(squarerootofwidth×length)3.
Mean values of five mice/group ±SEM are shown. The experiment was repeated three
times with similar results. *,P<.05 HeLa versus pCRCAL/HeLa.
(a)(b)(c)


## 4. Discussion

We
report that aspirin inhibited the proliferation of cervical adenocarcinoma
cells in a time- and dose-dependent manner. This agrees with other studies
showing that aspirin inhibited the proliferation of cancer cells [2, 4, 8–12]. Aspirin has antitumor
effects in the colon through induction of quiescence and apoptosis [13]. Apoptosis was shown to
be responsible for the cell growth inhibitory effects of aspirin in HT29 human
colon carcinoma cells. Our morphological observation of nuclear condensation after
aspirin treatment suggests that aspirin increases apoptosis in cervical cancer
cells (see Figure 1). These results demonstrate that aspirin is an effective
antitumor drug that induces apoptosis in cervical cancer cells.A few molecular
mechanisms of aspirin have been proposed. One of these mechanisms is
COX-independent [14, 15]. It is
well known that activation of p53 expression is involved [16]. In this study, we have
shown that aspirin induces the calpain gene and calpain gene activation
inhibits the tumor formation. These results support the previous findings that
aspirin induces apoptosis by the regulation of bcl-2 and caspase-3 in human
cervical cancer cells [3, 17]. Therefore,
aspirin might play roles in the inhibition of tumor formation through
activation of calpain gene.Calpain
is a calcium-dependent cysteine protease that is implicated in calcium-dependent
cell death [17, 18]. Calpain
plays an essential role in apoptotic commitment by cleaving Bax and generating
the Bax/p18 fragment, which in turn mediates cytochrome c release and initiates
the apoptotic execution [19]. Calpain activation
plays a critical role in cancer cell adhesion and motility [20]; and calpain could be
related to a therapeutic strategy targeting multiple disease states [21–24]. In our experiments,
caspase-3 activity was increased in the calpain-transfected HeLa cells,
suggesting a correlation of calpain and caspase-3 (see Figure 3(b)). The
involvement of caspase-3 in the calpain action is in agreement with the results
in the photoreceptor cell, where calpain executes apoptosis via modulation of
caspase-3 activity [25]. Accompanying the
increased caspase-3 activity, tumor growth was reduced by calpain gene expression,
leading to the role of calpain as an apoptosis mediator (see Figure 3(c)). Fushimi
et al. have analyzed calpain release from cultured chondrocytes stimulated by a
proinflammatory cytokine, tumor necrosis factor-α (TNF-α) [4]. The effects of NSAIDs
on calpain release were also examined. However, their results were in contrast
to our expectation. NSAIDs examined (aspirin, loxoprofen-SRS, diclofenac
sodium, indomethacin, and NS398) potently inhibited TNF-α-induced release of calpain [4]. In addition, they
showed that PGE2 alone failed to stimulate, but it significantly augmented
the release of calpain in the presence of 1 ng/mL TNF-α in HCS-2/8 cells. Moreover, inhibition of
calpain release by an NSAID, loxoprofen-SRS, was significantly reversed by 100 nM PGE2. Therefore, further studies are necessary to clarify the relationship
implicated in the aspirin treatment.


## 5. Conclusion

Aspirin causes growth inhibition of cervical cancer cells through activation of apoptosis. We suggest that aspirin may have cancer-preventing effects through calpain gene expression, which leads to caspase-3 activation.



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*Source: 285374-2008-09-29.xml*