| P.O.Box 2345, Beijing 100023,China | World J Gastroenterol 2003 Apr 15;9(4):660-664 |
| Email: wjg@wjgnet.com | WJG ISSN 1007-9327 CN 14-1219/ R |
| http:// www.wjgnet.com | Copyright © 2003 by The WJG Press |
Tributyrin inhibits human gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis arrest
Jun Yan, Yong-Hua Xu
Jun Yan, Yong-Hua Xu,
Lab of Molecular and Cellular Oncology and Lab of Molecular Cell Biology,
Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological
Sciences, Chinese Academy of Sciences, Shanghai 200031, China
Supported by the
Major State Basic Research (973) Program of China, (G1999053905) and National
Natural Science Foundation of China, No. 30170207
Correspondence to: Dr.
Yong-Hua Xu, Lab of Molecular and Cellular Oncology, Institute of Biochemistry
and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy
of Sciences, 320 Yue Yang Road, Shanghai 200031, China. yhxu@sunm.shcnc.ac.cn
Telephone:
+86-21-54921361 Fax: +86-21-54921361
Received:
2002-10-09 Accepted: 2002-11-04
Abstract
AIM: To evaluate the effects of
tributyrin, a pro-drug of natural butyrate and a neutral short-chain fatty acid
triglyceride, on the growth inhibition of human gastric cancer SGC-7901 cell.
METHODS:
Human gastric cancer SGC-7901 cells were exposed to tributyrin at 0.5, 1, 2, 5,
10 and 50 mmol.L-1 for 24-72 h. MTT assay was applied to detect the
cell proliferation. [3H]-TdR uptake was measured to determine DNA
synthesis. Apoptotic morphology was observed by electron microscopy and
Hoechst-33258 staining. Flow cytometry and terminal deoxynucleotidyl transferase-mediated
dUTP nick end labeling (TUNEL) assay were performed to detect tributyrin-triggered
apoptosis. The
expressions of PARP, Bcl-2 and Bax were examined by Western blot assay.
RESULTS:
Tributyrin could initiate growth inhibition of SGC-7901 cell in a dose- and
time-dependent manner. [3H]-TdR uptake by SGC-7901 cells was reduced to 33.6 %
after 48 h treatment with 2 mmol.L-1
tributyrin, compared with the control (P<0.05). Apoptotic morphology
was detected by TUNEL assay. Flow cytometry revealed that tributyrin could
induce apoptosis of SGC-7901 cells in dose-dependent manner. After 48 hours
incubation with tributyrin at 2 mmol.L-1,
the level of Bcl-2 protein was lowered, and the level of Bax protein was
increased in SGC-7901, accompanied by PARP cleavage.
CONCLUSION:
Tributyrin could inhibit the growth of gastric cancer cells effectively in
vitro by inhibiting DNA synthesis and inducing apoptosis, which was
associated with the down-regulated Bcl-2 expression and the up-regulated Bax
expression. Therefore, tributyrin might be a promising chemopreventive and
chemotherapeutic agent against human gastric carcinogenesis.
Yan J, Xu YH. Tributyrin inhibits human
gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis
arrest. World J Gastroenterol 2003; 9(4): 660-664
http://www.wjgnet.com/1007-9327/9/660.htm
INTRODUCTION
Gastric cancer is one of the most common causes
of malignancy-related death worldwide. In China, the annual average mortality
rate of gastric carcinoma is as high as 16 per 100 thousand[1].
Environmental factors, diet that is high in salts and low in fresh fruit and
vegetables are regarded as the risk of stomach cancer[2-6]. Although
plenty of advances have been made in the gastrointestinal medicine, the
inability to diagnose early and treat effectively of the gastric cancer remains
an unsolved problem for clinicians[7-23].
Chemoprevention
and chemotherapy including the use of natural products, synthetic compounds or
dietary substances are promising ways to stop or reverse the process of
carcinogenesis[24]. Large number of minor dietary components has been
found to inhibit carcinogenesis at various stages[25]. Tributyrin is
a neutral short-chain fatty acid triglyceride existed in some spice plants at
low levels in nature[26], and has been approved as a food additive in
the United States[27]. Tributyrin is also a pro-drug of natural
butyrate synthesized by the bacterial fermentation of various complex
carbohydrates unabsorbed in the digestive tract[28] and has been
reported bearing anti-tumor effect on neoplastic cells[27, 29, 30] as
well as inhibiting proliferation and stimulating differentiation in multiple
cancer cell lines. Most importantly, tributyrin is more lipophilic compared with
the butyrate and can be metabolized by the intracellular lipases, progressively
releasing therapeutically effective butyrate directly in the cell[26, 31].
However, the underlying mechanisms of tributyrin against different types of
tumor remain to be understood and so far, the effect of tributyrin on gastric
cancer cells has not been reported yet.
In this study, we
are trying to evaluate the ability of tributyrin to inhibit cell proliferation,
arrest DNA synthesis and induce apoptosis in human gastric cancer SGC-7901 cells
and go further into some apoptosis-related events in these processes.
MATERIALS AND METHODS
Cell lines and reagents
Human gastric cancer cell line SGC-7901 was
provided by the Cell Bank of Shanghai Institute of Cell Biology, Chinese Academy
of Sciences (Shanghai, China). Cells were cultured in Dulbecco's Modified
Eagle Medium (DMEM; Life Technologies Inc., Grand Island, NY) supplemented with
10 % fetal calf serum (FCS; Life Technologies Inc., Rockville, MD), penicillin
(100 kU.l-1) and streptomycin (0.1 g.l-1)
at 37 ℃
in a 5 % CO2-95 % air atmosphere. Antibodies against Bax, Bcl-2, PARP,
and Actin were obtained from Santa Cruz. Other chemicals used in the study were
purchased from Sigma Chemical Co (St. Louis, MO, USA). In situ cell death
detection kit was purchased from Roche Diagnostics. [3H]-TdR was
obtained from Amersham Company.
Assessment of cell
proliferation
MTT assay was conducted to determine the cell
proliferation. SGC-7901 cells were seeded in a 96-well plate (1×104.well-1) as described
previously[32]. In brief, after 24 h incubation cells were treated
with tributyrin for three days and untreated cells served as a control. Prior to
the determination, 5 mL of
the 2.5 g.l-1 stock solution of
3-[4,5-dimethylthiaolyl]-2,5-diphenyl-tetrazolium bromide (MTT) was added to
each well. After 4 h incubation, the culture media were discarded followed by
addition of 100 mL of DMSO to each well and vibration for 10 min. The absorbance
(A) was measured at 492nm with a microplate reader. The percentage of viable
cells was calculated as follows:(A of experimental group/A of control group)×100 %.
[3H]-TdR incorporation
The cells were treated with 2 mmol.l-1
Tributyrin for the indicated time as described previously[33]. 74kBq
of [3H]-TdR were added to cells 3 h before the end of the culture.
Cells were then washed with ice-cold PBS and 5 % trichloroacetic acid and lyzed
in 0.25 mol.l-1 NaOH. The lysates were
neutralized with 3 mol.l-1 HCl and [3H]-TdR
uptake was measured with Beckman LS5000 TD liquid scintillation counter.
Transmission electron microscopy
The cultured cells treated with 2 mmol.l-1
tributyrin for 48 h were trypsinized and harvested, respectively. Subsequently
the cells were immersed with Epon 821, embedded in capsules and converged at 60 ℃
for 72 h, then they were prepared into ultrathin section (60 nm) and stained
with uranyl acetate and lead citrate. Cell ultrastructure was examined by
transmission electron microscopy.
Morphological change of apoptosis
The morphological changes of cell apoptosis
were determined under fluorescence microscope. Briefly, the experimental cells
were pelleted and fixed in 200 ml.l-1
ethanol/phosphate-buffered saline (PBS), stained with 5 mg.l-1
Hoechst-33258 for 10min at room temperature, then visualized under fluorescence
microscope.
TUNEL assay
Apoptosis of SGC-7901 cells was analyzed by
using in situ cell death detection kit. The method is essentially based
on the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)
technique. In brief, after cells were treated with or without tributyrin for the
indicated time, they were fixed overnight in 100 g.l-1
formaldehyde, then treated with proteinase K and H2O2,
labeled with fluorescein dUTP in a humid box at 37 ℃
for 1 h and visualized under fluorescence microscope. The cells without addition
of TdT enzyme were used as negative control.
Flow cytometry
After harvested, the experimental cells were
washed with PBS twice and fixed with 700 mL.l-1
ethanol at 4 ℃
overnight. The fixed cells were washed twice with PBS and stained with 800 mL
propidium iodide and 200 mL
deoxyribonulcease-free ribonuclease A in PBS. The fluorescence density of
propidium iodide-stained nuclei was determined by flow cytometry.
Western blot analysis
The experimental cells were lysed in lysis
buffer [25 mmol.l-1 HEPES, 1.5 % Triton
X-100, 1 % sodium deoxycholate, 0.1 % SDS, 0.5 mol.l-1
NaCl, 5 mmol.l-1 EDTA, 50 mmol.l-1
NaF, 0.1 mmol.l-1 sodium vanadate, 1 mmol.l-1
phenylmethylsulfonyl fluoride (PMSF), and 0.1 g.l-1
leupeptin (pH7.8)] at 4 ℃
with sonication. The lysates were centrifuged at 15 000 g for 15 min at 4 ℃ and
the proteins were separated on SDS-PAGE, transferred to nitrocellulose filter
and incubated with antibodies against Bcl-2, Bax, PARP, and Actin, respectively.
Then the membrane was incubated with peroxidase-conjugated secondary antibodies.
Detection was performed with enhanced chemiluminescence reagent.
Statistical analysis
Student's t
test was used to assess statistical significance of differences. If P<0.05,
the difference was considered statistically significant.
RESULTS
Inhibition of human gastric cancer
SGC-7901 cell proliferation by tributyrin
The experimental SGC-7901 cells were treated
with various concentrations of tributyrin for 1-3 days and the cell viability
was determined as described above by MTT assay. As shown in Figure 1, tributyrin
could inhibit the growth of gastric cancer cells in a dose- and time-dependent
manner. Cell growth was suppressed by 24.9 %, 36.6 %, 50.3 %, 60.6 %, 84.1 % and
91.3 % after 72 h treatment with tributyrin at 0.5, 1, 2, 5, 10 and 50 mmol.l-1,
respectively. It was noted that tributyrin at 50 mmol.l-1
had an inhibitory effect of more than 90 % on the tumor cell growth after 48-72
h treatment. The IC50 value of tributyrin for SGC-7901 cell at 72 h was 2 mmol.l-1.
Figure 1 (PDF) Effect of tributyrin on cell growth in SGC-7901 cells. The cells were treated with various concentrations of tributyrin for 24, 48 and 72 h. The antiproliferative effect was measured by MTT assay. Results were expressed as the means ±SD from three independent determinations.
DNA synthesis arrest by
tributyrin
Since the IC50 value of tributyrin was 2 mmol.l-1,
the concentration was used for the following assay. Tributyrin inhibited the [3H]-TdR
uptake by SGC-7901 cells in a time-dependent manner. Compared with the control,
the DNA synthesis of tumor cells was significantly reduced by 66.4 %, 92.2 % and
90.1 % after 48 h, 72 h and 96 h treatment with tributyrin, respectively, (P<0.05,
Figure 2).
Figure
2 (PDF) Inhibitory effect of tributyrin on
DNA synthesis incorporated with 3H-TdR. With the concentration of 2
mmol.l-1, tributyrin inhibited the [3H]-TdR
uptake by SGC-7901 cells in a time-dependent manner. Results were expressed as
means ±SD
from three independent determinations.
Tributyrin induction of
apoptosis
Morphological changes After
48 h of exposure to tributyrin, gastric cancer cells began to show morphologic
features of apoptosis, which manifested as cell shrinkage, chromatin
condensation and nuclear pyknosis, etc by transmission electron
microscopy (Figure 3). The tributyrin-treated SGC-7901 cells labeled with
Hoechst-33258 also showed apoptotic features including nuclear shrinkage or
fragmentation by fluorescence microscopy (Figure 4).
Figure 3 Ultrastructural
changes of the gastric cancer cells treated with 2 mmol.l-1
tributyrin for 48 h. (A) The
control SGC-7901 cell; (B) the
experimental cell showing early changes of apoptosis in which nuclear chromatin
condensation and cell shrinkage were observed (B).
Figure 4
Tributyrin-induced apoptosis in SGC-7901 cells stained with Hoechst-33258. A:
the control SGC-7901 cells; B:
the experimental cells showing nuclear shrinkage or fragmentation.
Figure 5 Tributyrin-induced
apoptosis by TUNEL assay. A:
the positive control cells; B:
the negative control cells; C:
the experimental cells treated with tributyrin at 2 mmol.l-1
for 2 days.
Figure
6 (PDF) Tributyrin-induced apoptosis in
SGC-7901 cells by flow cytometry. (A) The control cells, (B)-(D) The
experimental cells treated with tributyrin at 0.5, 2 and 10 mmol.l-1
respectively for 48 h. (E) Apoptosis rates in SGC-7901 cells treated with 0.5, 2
and 10 mmol.l-1
or without tributyrin for the indicated times.
TUNEL assay
The TUNEL assay revealed that tributyrin
could induce the apoptosis of SGC-7901 cells, while the negative control did not
show any signs of fluorescence signals (Figure 5).
Flow cytometry
Cell cycle analysis in SGC-7901 cells treated
with tributyrin revealed that a sub-G1 apoptotic peak appeared (Figure 6). The
apoptosis rate in tributyrin-treated tumor cells was increased in a time- and
dose-dependent manner. When treated with 2 mmol.l-1
tributyrin for 72 h, the experimental SGC-7901 cells showed a 41.5 % of
apoptosis.
Differential expression of Bcl-2
and Bax protein and PARP cleavage in tributyrin-treated cells
After treated with indicated concentrations
of tributyrin for 48 h, the expression of Bcl-2 protein was markedly decreased
while that of Bax displayed an increased trend. PARP cleavage in the
experimental cells appeared at 0.5 mmol.l-1
and was obvious at 2 mmol.l-1
of tributyrin treatment for 48 h (Figure 7).
Figure 7 (PDF) The expression of Bcl-2, Bax protein and PARP cleavage in tributyrin-treated SGC-7901 cells. (1) The control cells; (2)-(4) The experimental cells treated with tributyrin for 48 h at 0.5, 2 and 10 mmol.L-1, respectively.
DISCUSSION
It has been reported tributyrin, a substance that
naturally exists in some foods, was a potent agent against various malignancies,
including colon and pancreas carcinomas, and that 1 mmol of tributyrin could
result in an inhibitory effect comparable with 3 mmol of butyrate[32,33].
The high lipophilic property and the long duration in blood made tributyrin a
promising anti-tumor agent. However, the effects of tributyrin on gastric cancer
cells have not been reported.
The present study
demonstrated that tributyrin could inhibit the growth of human gastric cancer
SGC-7901 cells in a dose- and time-dependent manner, which might be caused by
DNA synthesis arrest as shown in our experiment via preventing SGC-7901 cells
from progressing into S-phase and ultimately blocking the cell proliferation.
The inhibition of DNA synthesis was more than 90 % when SGC-7901 cells were
treated with tributyrin at 2 mmol.l-1 for
48-72 h.
Besides DNA
synthesis arrest, the induced cell death was another major reason for the cell
growth inhibition. Apoptosis, also called programmed cell death, is a natural
process of cell suicide which plays a critical role in the development and
homeostasis of metazoans[34,35]. Our results that tributyrin could
induce apoptosis in SGC-7901 cells revealed by the typical apoptotic
alterations, including the morphological changes by electron microscopy,
positive Hoechst-33258 staining, DNA fragmentation by TUNEL assay and apoptotic
sub-G1 peak by flow cytometry.
Apoptosis is a
complex process regulated by a variety of factors[36-39]. The members
of the Bcl-2 family are important regulators in the apoptotic pathway with
individual members that can suppress (eg Bcl-2, Bcl-xl) or promote (eg Bax, Bad)
apoptosis. As an oncogene-derived protein, Bcl-2 confers a negative control in
the pathway of cellular suicide machinery, whereas Bax, a Bcl-2-homologous
protein, promotes cell death by competing with Bcl-2. Introduction of Bcl-2 into
most eukaryotic cells has been reported to be able to protect the recipient cell
from a wide variety of stress applications that lead to cell death[40,41].
In the present study, we observed that the expression of Bcl-2 was reduced and
that of Bax was up-regulated, indicating the reduced ratio of Bcl-2/Bax might
serve as a mechanism of SGC-7901 cells apoptosis induced by tributyrin. Its
subsequent event might be the release of cytochrome c and caspase-3 activation.
On the other hand, the cleavage of PARP, one of caspase-3 downstream target[42],
was also observed in the experimental SGC-7901 cells with the increase of
tributyrin concentrations. However, PARP could also be cleaved through a
parallel caspase-3 independent pathway. Therefore, the exact mechanism
underlying the apoptosis of SGC-7901 cells needed to be further investigated.
In summary, we
have demonstrated that tributyrin, an oral analogue of butyrate, could induce
DNA synthesis arrest and apoptosis in human gastric cancer SGC-7901 cells in
vitro. The effect was dose- and time-dependent. The apoptotic mechanism of the
SGC-7901 cells induced by tributyrin was at least via the reduction of Bcl-2/Bax
ratio. These data suggested that further evaluation of tributyrin, a promising
anti-tumor agent, for the treatment gastric cancer was warranted.
ACKNOWLEDGEMENT
We thank Dr. Rugang Zhang from Institute of
Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences,
Chinese Academy of Sciences, for his helpful suggestion.
REFERENCES
1
Xue FB, Xu YY, Wan Y, Pan BR, Ren J, Fan DM. Association of H. pylori
Infection with gastric carcinoma: a Meta analysis.
World J Gastroenterol 2001; 7: 801-804
2
Sugie S, Okamoto K, Watanabe T, Tanaka T, Mori H. Suppressive effect of
irsogladine maleate
on N-methyl-N-nitro-N-nitrosoguanidine (MNNG)-initiated
and glyoxal-promoted gastric carcinogenesis in rats. Toxicology
2001; 166: 53-61
3
Palli D, Russo A, Saieva C, Salvini S, Amorosi A, Decarli A. Dietary and
familial determinants of 10-year survival
among patients with gastric carcinoma. Cancer
2000; 89: 1205-1213
4
Mathew A, Gangadharan P, Varghese C, Nair MK. Diet and stomach cancer:a
case-control study in South India. Eur J
Cancer Prev 2000; 9: 89-97
5
Palli D. Epidemiology of gastric cancer: an evaluation of available
evidence. J Gastroenterol 2000; 35(Suppl 12): 84-89
6
Palli D, Russo A, Ottini L, Masala G, Saieva C, Amorosi A, Cama A, D扐mico
C, Falchetti M, Palmirotta R, Decarli A,
Costantini RM, Fraumeni JF Jr. Red meat, family
history, and increased risk of gastric cancer with microsatellite
instability. Cancer Res 2001; 61:
5415-5419
7
Skoropad V, Berdov B, Zagrebin V. Concentrated preoperative radiotherapy
for resectable gastric cancer: 20-years follow-
up of a randomized trial. J Surg Oncol 2002;
80: 72-78
8
Yao XX, Yin L, Sun ZC. The expression of hTERT mRNA and cellular immunity
in gastric cancer and precancerosis. World
J Gastroenterol 2002; 8: 586-590
9
Fahey JW, Haristoy X, Dolan PM, Kensler TW, Scholtus I, Stephenson KK,
Talalay P, Lozniewski A. Sulforaphane
inhibits extracellular, intracellular, and
antibiotic-resistant strains of Helicobacter pylori and prevents benzo[a]pyrene-
induced stomach tumors. Proc Natl Acad Sci U S A
2002; 99: 7610-7615
10
Martin RC 2nd, Jaques DP, Brennan MF, Karpeh M. Extended local resection
for advanced gastric cancer: increased
survival versus increased morbidity. Ann Surg
2002; 236: 159-165
11 Yu WL,
Huang ZH. Progress in studies on gene therapy for gastric cancer. Shijie Huaren
Xiaohua Zazhi 1999; 7: 887-889
12
Chen GY, Wang DR. The expression and clinical significance of CD44v in
human gastric cancers. World J Gastroenterol
2000; 6: 125-127
13 Wang RQ,
Fang DC, Liu WW. MUC2 gene expression in gastric cancer and preneoplastic lesion
tissues. Shijie Huaren
Xiaohua Zazhi 2000; 8: 285-288
14 Guo YQ,
Zhu ZH, Li JF. Flow cytometric analysis of apoptosis and proliferation in
gastric cancer and precancerous lesion.
Shijie Huaren Xiaohua Zazhi 2000; 8:
983-987
15 Chen SY,
Wang JY, Ji Y, Zhang XD, Zhu CW. Effects of Helicobacter pylori and protein
kinase C on gene mutation in
gastric cancer and precancerous lesions. Shijie
Huaren Xiaohua Zazhi 2001; 9: 302-307
16
Xu AG, Li SG, Liu JH, Gan AH. Function of apoptosis and expression of the
proteins Bcl-2, p53 and C-myc in the development
of gastric cancer. World J Gastroenterol 2001;
7: 403-406
17
Zhou HP, Wang X, Zhang NZ. Early apoptosis in intestinal and diffuse
gastric carcinomas. World J Gastroenterol
2000; 6: 898-901
18
Zhang FX, Zhang XY, Fan DM, Deng ZY, Yan Y, Wu HP, Fan JJ. Antisense
telomerase RNA induced human gastric cancer
cell apoptosis. World J Gastroenterol 2000; 6:
430-432
19
Gu QL, Li NL, Zhu ZG, Yin HR, Lin YZ. A study on arsenic trioxide
inducing in vitro apoptosis of gastric cancer cell lines. World
J Gastroenterol 2000; 6: 435-437
20
Wu K, Shan YJ, Zhao Y, Yu JW, Liu BH. Inhibitory effects of
RRR-alpha-tocopheryl succinate on benzo(a)pyrene (B(a)P)
a 2induced forestomach carcinogenesis in female
mice. World J Gastroenterol 2001; 7: 60-65
21
Jung YD, Mansfield PF, Akagi M, Takeda A, Liu W, Bucana CD, Hicklin DJ,
Ellis LM. Effects of combination anti-
vascular endothelial growth factor receptor and
anti-epidermal growth factor receptor therapies on the growth of
gastric cancer in a nude mouse model. Eur J
Cancer 2002; 38: 1133-1140
22
Cui RT, Cai G, Yin ZB, Cheng Y, Yang QH, Tian T. Transretinoic acid
inhibits rats gastric epithelial dysplasia induced
by N-methyl-N-nitro-N-nitrosoguanidine:
influences on cell apoptosis and expression of its regulatory genes. World
J Gastroenterol 2001; 7: 394-398
23
Gonzalez CA, Sala N, Capella G. Genetic susceptibility and gastric cancer
risk. Int J Cancer 2002; 100: 249-260
24
Morse MA, Stoner GD. Cancer chemoprevention: Principles and prospects.
Carcinogenesis 1993; 14: 1737-1746
25
Wattenberg LW. Inhibition of carcinogenesis by minor dietary
constituents. Cancer Res 1992; 52(Suppl 7): S2024-S2029
26
Bach A, Metais P. Fats with short and medium chains. Physiological,
biochemical, nutritional and therapeutic aspects. Ann
Nutr Alim 1970; 24: 75-144
27
Heerdt BG, Houston MA, Anthony GM, Augenlicht LH. Initiation of growth
arrest and apoptosis of MCF-7 mammary
carcinoma cells by tributyrin, a triglyceride
analogue of the short-chain fatty acid butyrate, is associated with
mitochondrial activity. Cancer Res 1999; 59:
1584-1591
28
Scheppach W. Effects of short chain fatty acids on gut morphology and
function. Gut 1994; 35: S35-38
29
Schroder C, Eckert K, Maurer HR. Tributyrin induces growth inhibitory and
differentiating effects on HT-29 colon cancer cells
in vitro. Int J Oncol 1998; 13: 1335-1340
30
Maier S, Reich E, Martin R, Bachem M, Altug V, Hautmann RE, Gschwend JE.
Tributyrin induces differentiation, growth
arrest and apoptosis in androgen-sensitive and
androgen-resistant human prostate cancer cell lines. Int J Cancer
2000; 88: 245-251
31
Egorin MJ, Yuan ZM, Sentz DL, Plaisance K, Eiseman JL. Plasma
pharmacokinetics of butyrate after intravenous
administration of sodium butyrate or oral
administration of tributyrin or sodium butyrate to mice and rats. Cancer
Chemother Pharmacol 1999; 43: 445-453
32
Ying H, Yu Y, Xu Y. Cloning and characterization of F-LANa, upregulated
in human liver cancer. Biochem Biophys Res
Comm 2001; 286: 394-400
33
Clarke KO, Feinman R, Harrison LE. Tributyrin, an oral butyrate analogue,
induces apoptosis through the activation of
caspase-3. Cancer Lett 2001; 171: 57-65
34
Green DR, Reed JC. Mitochondria and apoptosis. Science 1998; 281:
1309-1312
35
Ashkenazi A, Dixit VM. Apoptosis control by death and decoy receptors.
Curr Opin Cell Biol 1999; 11: 255-260
36
Adams JM, Cory S. The Bcl-2 protein family: arbiters of cell survival.
Science 1998; 281: 1322-1326
37
Li HL, Chen DD, Li XH, Zhang HW, Lu JH, Ren XD, Wang CC. JTE-522-induced
apoptosis in human gastric
adenocarcinoma [correction of adenocarinoma] cell
line AGS cells by caspase activation accompanying cytochrome C
release, membrane translocation of Bax and loss
of mitochondrial membrane potential. World J Gastroenterol
2002; 8: 217-223
38 Fan XQ, Guo YJ. Apoptosis in oncology. Cell Res 2001; 11:
1-7
39 Yuan RW,
Ding Q, Jiang HY, Qin XF, Zou SQ, Xia SS. Bcl-2, P53 protein expression and
apoptosis in pancreatic cancer.
Shijie Huaren Xiaohua Zazhi 1999; 7:
851-854
40
Basu A, Haldar S. The relationship between Bcl2, Bax and p53:
consequences for cell cycle progression and cell death.
Mol Hum Reprod 1998; 4: 1099-1109
41
Chang YC, Xu YH. Expression of Bcl-2 inhibited Fas-mediated apoptosis in
human hepatocellular carcinoma BEL-7404 cells.
Cell Res 2000; 10: 233-242
42
Tewari M, Quan LT, O扲ourke K,
Desnoyers S, Zeng Z, Beidler DR, Poirier GG, Salvesen GS, Dixit VM. Yama/CPP32b,
a mammalian homolog of CED-3, is a
CrmA-inhibitable protease that cleaves the death substrate poly(ADP-ribose)
polymerase. Cell 1995; 81: 801-809
Edited by Zhu L
