Heparin/heparan sulfate interacting protein plays a role in apoptosis induced by anticancer drugs

Jian-Jun Liu1, Jinqiu Zhang1, Sriram Ramanan1, JoAnne Julian2, Daniel D. Carson2 and Shing Chuan Hooi1,3

1 Department of Physiology, Faculty of Medicine, National University of Singapore, Republic of Singapore and 2 Department of Biological Science, University of Delaware, Newark, USA

3 To whom correspondence should be addressed. Email: phshsc{at}nus.edu.sg


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Heparin/heparan sulfate interacting protein (HIP, also known as ribosome protein L29) is involved in cell–cell and cell–extracelluar matrix interactions and influences cell proliferation, migration and differentiation. In the present study, we investigated the role of HIP in anticancer drug-induced apoptosis. Both colon cancer HCT-116 and HT-29 cells showed dose-dependent down-regulation of HIP expression when treated with sodium butyrate. The down-regulation was negatively correlated with the percentage of apoptotic cells (R = –0.955, P = 0.03 and R = –0.792, P = 0.06 for HCT-116 and HT-29 cells, respectively). The correlation between HIP expression and apoptosis in HCT-116 cells was also evident in the differential expression of HIP in the floating and adherent cell populations. Most apoptotic cells were distributed in the floating population. HIP expression in this population was ~30% lower than adherent and untreated control cells. HIP expression in HCT-116 cells was also significantly decreased in parallel with apoptosis after treatment with 50 µM camptothecin and 20 µM 5-fluorouracil. This indicates that the down-regulation of HIP may be a general phenomenon in anticancer drug-induced apoptosis. The down-regulation of HIP occurred in the early phase of apoptosis, in parallel with the activation of caspase-3 and the externalization of phosphatidylserine. The functional significance of HIP in apoptosis was shown by knocking down the expression of HIP using small interfering RNA. A 50% reduction in HIP expression was sufficient to increase the percentage of apoptotic cells (from 11 to 20%) and increase the sensitivity of the cells to apoptosis induced by 1 mM butyrate by 60%. These results indicate that HIP may play an important role in anticancer drug-induced apoptosis.

Abbreviations: 5-FU, 5-fluorouracil; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; HIP, heparin/heparan sulfate interacting protein; siRNA, small interfering RNA


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Heparin/heparan sulfate interacting protein (HIP, also known as ribosome protein L29, RPL29) is regulated during cancer development and may play a role in carcinogenesis (1,2). There is evidence to suggest that HIP may regulate cell proliferation and differentiation in cancer cells. We had shown previously that the expression of HIP was up-regulated in ~70% of colon cancers compared with matched adjacent normal colon mucosa and that expression was correlated to differentiation status of the cell (1). Similar findings were reported for thyroid carcinoma (2). HIP interacts with ubiquitous proteins on the cell surface known as heparin/heparan sulfate proteoglycans (HSPGs) (3,4). HSPGs are thought to be involved in cell adhesion, growth, differentiation and proliferation via their interactions with soluble growth factors, extracellular matrix, cytokines and adhesion molecules (57). These processes are important to the proliferation, progression, invasion and metastasis of cancer cells (5,8). HIP was isolated from a uterine epithelial cell line and was later found to be ubiquitously expressed on the cell surface of many different tissues (3,4,9). The binding of HIP to HSPGs in the extracellular matrix and cell surfaces regulates cellular growth (10).

Cancer results from an imbalance between cell proliferation and apoptosis (11). In this study, we sought to determine whether HIP plays a role in regulating apoptosis in the cell. We studied the regulation of HIP during apoptosis induced by anticancer drugs. We also studied the effect of knocking down the expression of HIP on apoptosis and the response of cancer cells to anticancer therapy. We were interested to determine if HIP is involved in the modulation of the apoptotic response to anticancer drugs.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Materials
The human colon cancer cell lines HT-29 and HCT-116 were purchased from the American Type Culture Collection (Rockville, MD). Fetal bovine serum (FBS), modified McCoy 5A medium, sodium butyrate, camptothecin, 5-fluorouracil (5-FU) and propidium iodide were from Sigma Aldrich (St Louis, MO). Active caspase-3 antibody (polyclonal rabbit IgG) was purchased from Oncogene (Boston, MA) and mouse polyclonal glyceraldehyde-3-phosphate dehydrogenase (GAPDH) antibody was from Chemicon International (Temecula, CA). The polyclonal anti-cathepsin D antibody was obtained from Santa Cruz (Santa Cruz, CA). Annexin-V FLOUS staining kit was purchased from Roche Diagnostics (Mannheim, Germany). The transfection reagent Oligofectamine was obtained from Invitrogen (Carlsbad, CA). Small interfering RNA duplex (siRNA) was synthesized by Dharmacon (Lafayette, CO). The generation of the rabbit polyclonal anti-HIP antibody has been described previously (12). In brief, a synthetic peptide of the HIP sequence was conjugated to the keyhole limpet hemocyanin protein and was used for rabbit immunization. The polyclonal antibody was affinity purified.

Cell culture
HT-29 and HCT-116 cells were cultured in modified McCoy 5A medium supplemented with 10% fetal bovine serum (v/v), 100 IU/ml penicillin, 10 µg/ml streptomycin and maintained at 37°C in an incubator containing 5% CO2. Cells were harvested with 0.05% trypsin/0.02% (w/v) EDTA at ~80% confluence and subcultured. After incubation overnight for attachment, the cells were treated with medium containing sodium butyrate, camptothecin or 5-FU of different concentrations. Sodium butyrate was dissolved in H2O as 1 M stock solution. Camptothecin and 5-FU were dissolved in DMSO as 10 mM stock solution and kept at 4°C.

Western blot analysis
After treatment with anticancer drugs, the cells were harvested with a rubber policeman and washed once with cold PBS. Proteins were extracted by suspending the cells in extraction buffer containing 50 mM Tris pH 7.0, 6 M urea, 1% (w/v) SDS, 1% (v/v) ß-mercaptoethanol and 0.01% (w/v) PMSF. Cells were sonicated for 20 s on ice, then centrifuged at 10 000 g for 10 min at 4°C. Protein concentrations were quantified using bovine serum albumin as standard.

Electrophoresis was performed using 15% SDS–polyacrylamide gel. A total of 20 or 40 µg of protein were loaded in each lane for western blot analysis. The protein was then transferred to a nitrocellulose membrane by electro-blotting. After washing and blocking, the membrane was incubated with primary HIP antibody (rabbit IgG, 1:10 000 in PBS-T), active caspase-3 antibody [rabbit IgG, 1:250 in PBS-T and 5% (w/v) non-fat milk] or cathepsin D antibody (goat IgG, 1:1000) overnight at 4°C, followed by incubation with goat anti-rabbit or rabbit anti-goat secondary antibody conjugated with horseradish peroxidase at room temperature for 2 h (1:200 000, 1:20 000 and 1:5000 in PBS-T, 5% non-fat milk for HIP, active caspase-3 and cathepsin D, respectively). After washing, the membrane was incubated with chemiluminescent substrate for 5 min and then exposed to Kodak Biomax MS film (Rochester, NY). The chemiluminescent signal was also quantified by a chemiluminescent imager (Typhoon 9410 variable mode imager, Amersham, Buckinghamshire, UK).

To control for variation in loading, the expression of housekeeping gene GAPDH was also assayed by western blot analysis. After incubation with HIP, active caspase-3 and cathepsin D primary and secondary antibodies, the membrane was then re-probed with mouse anti-GAPDH polyclonal antibody (1:20 000 in PBS-T containing 5% non-fat milk) for 1 h, followed by incubation with goat anti-mouse secondary antibody conjugated with horseradish peroxidase (1:40 000) for 1 h at room temperature.

Apoptosis assay by DNA content analysis and annexin V staining
DNA content was analyzed as described previously (13). In brief, the cells were re-suspended in ice-cold 70% ethanol after treatment with anticancer drugs and stored at –20°C until analysis. The cellular DNA was stained with propidium iodide nuclear isolation medium [PBS containing 100 µg/ml propidium iodide, 0.6% NP-40 (w/v) and 100 µg/ml RNase A]. Flow cytometric analysis was performed in a BD FACSvantage flow cytometer (Franklin Lakes, NJ). The cell cycle phase distribution was analyzed using the Winmdi software.

Apoptosis was also assayed by annexin V staining. Briefly, the cells were trypsinized after treatment with anticancer drugs and washed once with cold PBS. The cells were re-suspended in the staining solution containing annexin V and propidium iodide and incubated for 15 min at room temperature according to the manufacturer's instructions, followed by flow cytometric analysis. Cells with high annexin V but low propidium iodide staining were considered as apoptotic cells.

siRNA transfection
The RNA sequence for HIP interference was 5'-AAACGUACCCAGGCCCCUACA-3' and the scrambled control siRNA was 5'-GCGCGCUUUGUAGGAUUCG-3'. The siRNA was dissolved in H2O as a 20 µM stock solution. 0.2 x 106 HCT-116 cells/well were seeded in a 6-well plate and incubated overnight to allow for the attachment of cells. For transfection, 240 pmol of siRNA was mixed with 200 µl serum-free opti-MEM medium and 12 µl Oligofectamine was mixed with 72 µl opti-MEM, respectively. After a 10-min incubation at room temperature, the siRNA and Oligofectamine were mixed and incubated for another 25 min. The mixture of siRNA and Oligofectamine was then added into each well, which contained 0.8 ml serum-free opti-MEM medium. Four hours later, McCoy 5A medium containing 20% FBS was added into each well. The cells were then incubated for 48 h at 37°C. To maximize the gene silencing effect of siRNA, the cells were transfected twice. At the end of the first transfection, cells were harvested by trypsinization and 0.2 x 106 cells were re-plated in each well of a 6-well plate. The next day, they were transfected for another 48 h as described above.

In the experiment to determine the percentage of apoptotic cells after knocking down HIP expression, the culture medium was changed to normal McCoy 5A medium with 10% FBS and antibiotics after the second transfection. The cells were harvested 24 h later for western blot analysis and apoptosis assays by annexin V staining.

In the experiment to determine the effect of reduced HIP expression on sensitivity of cells to apoptosis induced by butyrate, the cell culture medium was changed to McCoy 5A medium containing 1 mM sodium butyrate, 10% FBS and antibiotics at the end of the second transfection. The cells were harvested 24 h after drug treatment and apoptosis was assayed by annexin V staining.

Statistical analysis
The correlation ratio was calculated by Pearson's correlation test. For the comparison of the mean values of two groups, non-paired Student's t-test was applied and P < 0.05 was considered as significant.


    Results
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
HIP was down regulated in a dose-dependent manner in sodium butyrate-treated cells
The expression of HIP was decreased significantly after treatment with sodium butyrate in both HT-29 cells and HCT-116 cells after 48 h (Figure 1). There was a 20% down regulation of HIP after treatment with 4 mM butyrate in HT-29 cells. HIP expression was decreased to ~40% of the control at 8 mM butyrate (Figure 1A and B). Similar results were obtained for HCT-116 cells (Figure 1E and F). As reported previously, HCT-116 cells were more sensitive to butyrate-induced apoptosis (14). The percentage of apoptotic HCT-116 cells increased in a dose-dependent manner from as low as 0.5 mM sodium butyrate and reached a maximum at 2–4 mM concentrations (Figure 1G and H). In contrast, the percentage of apoptotic cells was increased significantly only at 2 mM butyrate in HT-29 cells (Figure 1C and D). The expression of HIP was negatively correlated with the percentage of apoptotic cells (R = –0.792, P = 0.06 for HT-29 cells; R = –0.955, P = 0.003 for HCT-116 cells, respectively).



View larger version (19K):
[in this window]
[in a new window]
 
Fig. 1. Changes in HIP expression after treatment with sodium butyrate and its correlation with apoptosis in HT-29 (AD) and HCT-116 cells (EH). The cells were treated with different concentrations of sodium butyrate for 48 h. Proteins were extracted and HIP expression was assayed by western blot analysis. Fifteen percent polyacrylamide gel was used and 20 µg protein was loaded in each lane. Apoptosis was assayed by both annexin V staining and DNA content analysis. (A and E) expression of HIP in HT-29 and HCT-116 cells by western blot analysis; (B and F) quantification of the expression of HIP normalized to GAPDH (HIP/GAPDH ratio) in HT-29 and HCT-116 cells at different concentrations of sodium butyrate; (C and G) percentage of apoptotic cells at different concentrations of sodium butyrate assayed by annexin V staining in HT-29 and HCT-116 cells; (D and H) percentage of sub-G1 fraction at different concentrations of sodium butyrate in HT-29 and HCT-116 cells. The percentage of apoptotic cells was negatively correlated with HIP expression in both HT-29 and HCT-116 cells (R = –0.792, P = 0.06 and R = –0.955, P = 0.003, respectively).

 
Differential regulation of HIP in the floating versus adherent cell populations after treatment with sodium butyrate
Sodium butyrate has multiple effects on the cells including inhibiting cell proliferation, inducing differentiation and apoptosis (15). The apoptotic cells have been reported to be distributed mainly in the floating rather than the adherent cell population (16). The two populations of cells were separated after treatment of HCT-116 cells with sodium butyrate for 48 h and the expression of HIP determined. Consistent with the earlier reports (16), we found most of the apoptotic cells in the floating population (Figure 2A and B). HIP expression was decreased by 30% in the floating cell population (P < 0.05 compared with control). The expression of HIP in the adherent cell population was not significantly changed (Figure 2C and D). To ensure that the reduction in HIP expression in the floating population was not a non-specific event of degradation accompanying apoptosis, we determined the expression of cathepsin D in these cells. We had shown previously that cathepsin D expression was increased by sodium butyrate treatment (14). As shown in Figure 2E, cathepsin D expression in the floating apoptotic cells was increased compared with control untreated cells.



View larger version (43K):
[in this window]
[in a new window]
 
Fig. 2. Differential expression of HIP in floating and adherent cell populations of HCT-116 cells. The cells were treated with 1.5 mM sodium butyrate for 48 h. The floating and adherent cells were collected separately and protein was extracted for western blot analysis. (A) Percentage of apoptotic cells assayed by annexin V staining; (B) percentage of sub-G1 cells by DNA content analysis; (C) expression of HIP by western blot analysis; (D) quantification of HIP expression normalized against GAPDH; (E) expression of cathepsin D by western blot analysis. Results shown are representative of three separate experiments. *P < 0.05 compared with control.

 
HIP expression in HCT-116 cells was also down regulated after treatment with camptothecin and 5-FU
HCT-116 cells were treated with 50 µM camptothecin and 20 µM 5-FU for 48 h. As shown in Figure 3A and B, camptothecin and 5-FU treatment resulted in a 7- and 10-fold increase in the percentage of apoptotic cells, respectively. Associated with the increase in the percentage of apoptotic cells, camptothecin and 5-FU caused a 40 and 50% reduction in HIP expression, respectively (Figure 3C).




View larger version (64K):
[in this window]
[in a new window]
 
Fig. 3. HIP expression in cells treated by camptothecin and 5-FU. HCT-116 cells were treated with 50 µM camptothecin or 20 µM 5-FU for 48 h. HIP expression was quantified by western blot analysis with GAPDH as an internal control. Apoptosis was assayed by both annexin V staining and DNA content analysis. (A) Percentage of apoptotic cells assayed by annexin V staining; (B) percentage of sub-G1 cells by DNA content analysis (mean ± SD, n = 3). (C) Expression of HIP by western blot analysis. Results shown are representative of three independent experiments.

 
HIP is down regulated in the early phase of apoptosis
The kinetics of HIP expression was studied in HCT-116 cells. As shown in Figure 4A and B, the down-regulation of HIP expression was observed as early as 24 h after treatment with sodium butyrate, in parallel with the activation of caspase-3 (Figure 4C), an executor of apoptosis and also one of the earliest markers (17). Another early marker of apoptosis, the externalization of phosphatidylserine (18), was also used to correlate the down-regulation of HIP and the onset of apoptosis. As shown in Figure 4D, the percentage of apoptotic cells increased significantly from 2% in the control to ~13% at 24 h. Thirty-two hours after treatment with sodium butyrate, most of the dead cells were still in the early phase of apoptosis.



View larger version (23K):
[in this window]
[in a new window]
 
Fig. 4. Correlation of HIP expression with caspase-3 activation and phosphatidylserine externalization. HCT-116 cells were treated with 5 mM sodium butyrate for 0, 4, 8, 16, 24 and 32 h. (A) Expression of HIP by western blot analysis; (B) quantification of HIP expression normalized against GAPDH; (C) active caspase-3 by western blot analysis; (D) percentage of apoptotic cells. HCT-116 cells were treated with 5 mM sodium butyrate for 0, 16, 24 and 32 h and labeled with annexin V and propidium iodide for flow cytometric analysis. Results shown are representative of three separate experiments.

 
Knocking down HIP expression in HCT-116 cells triggered spontaneous apoptosis and increased sensitivity to sodium butyrate-induced apoptosis
The expression of HIP was reduced by ~50% in HIP siRNA transfected cells compared with control cells transfected with scrambled siRNA (Figure 5A). In parallel with the reduction of HIP expression, the percentage of apoptotic cells increased from 11% in the control to 20% in the HIP siRNA treated cells (Figure 5B, P < 0.05 compared with the control). Cells with reduced expression of HIP were more sensitive to sodium butyrate-induced apoptosis. The percentage of apoptotic cells in HIP siRNA transfected cells was increased by ~60% compared with the control after treatment with 1 mM butyrate for 24 h (Figure 5C, P < 0.05).



View larger version (46K):
[in this window]
[in a new window]
 
Fig. 5. Effect of HIP siRNA on apoptosis in HCT-116 cells. Cells were transfected twice with 240 pmol HIP siRNA or scrambled siRNA as control. Spontaneous apoptosis and response of cells to sodium butyrate were assayed by annexin V staining as described above. (A) Western blot showing HIP and GAPDH expression; (B) percentage of apoptotic cells after knock-down of HIP expression (C) percentage of apoptotic cells after treatment with 1 mM sodium butyrate in HIP siRNA and scrambled siRNA transfected cells. Results shown are representative of three separate experiments. *P < 0.05 compared with control.

 

    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Our results showed that the expression of HIP was down regulated in both HCT-116 and HT-29 colon cancer cell lines by anticancer drug treatments. The down-regulation was inversely correlated to the percentage of apoptotic cells. Further, the down-regulation of HIP in HCT-116 cells occurred mainly in the population of cells that was undergoing apoptosis. Interestingly, the degree to which HIP expression was reduced in HCT-116 and HT-29 cells was correlated to the sensitivity of the cells to apoptosis. Our earlier findings and that of others have shown that HCT-116 cells were more sensitive to apoptosis induced by sodium butyrate compared with HT-29 cells (14). HT-29 cells expressed higher levels of HIP and were less sensitive to butyrate-induced reduction in HIP concentrations compared with HCT-116 cells. It is possible that the differential expression of HIP in the cells accounts for their different responses to butyrate treatment in regard to apoptosis.

The drugs used in the present study cause apoptosis through different mechanisms. It is thought that sodium butyrate induces apoptosis and differentiation through the inhibition of histone deacetylase activity, although other mechanisms may be involved (19). Camptothecin is an inhibitor of topoisomerase, while 5-FU induces apoptosis in cancer cells by disrupting DNA replication (20). The down-regulation of HIP by all three drugs used strongly suggests that it is related to apoptosis rather than a drug-specific event.

The correlation of HIP down-regulation with apoptosis suggests that HIP may play a role in regulating apoptosis in cells. Our data showed that the down-regulation of HIP occurred in the early stages of the apoptotic process, between 16 and 24 h, in parallel with the activation of caspase-3 and phosphatidylserine externalization. Both these events are markers of early apoptosis (17,18). In order to determine the functional significance of a reduction of HIP expression in the cell, we knocked down the expression of HIP in HCT-116 cells using HIP-specific siRNA. The HCT-116 cells were used because they were more amenable to transfection of siRNA compared with the HT-29 cells. We managed to decrease HIP expression by ~50% in these cells. The decrease in HIP expression caused an increase in apoptosis in the cells compared with control cells transfected with scrambled siRNA. This suggests that HIP has an anti-apoptotic effect in the cell. In addition, we found that cells expressing lower concentrations of HIP after knockdown with siRNA were more sensitive to butyrate-induced apoptosis. This indicates that HIP protects against butyrate-induced apoptosis. Overall, the data indicate that HIP has an anti-apoptotic effect in the cell.

There are several possible mechanisms by which lower HIP may protect against apoptosis. HIP may be involved in modulating cell–cell and cell–matrix interactions, which are vital for the survival of cells (6,21). Lower levels of HIP may decrease cell–cell and cell–matrix interactions causing apoptosis. HIP may also be involved in the regulation of the interactions between growth factors and their cognate receptors (10,22). A decrease in HIP changes this interaction, causing apoptosis. On the other hand, it is possible that altering the expression of HIP itself may trigger the apoptotic pathway directly. These questions will be addressed in subsequent studies.

The involvement of HIP in protecting cells against apoptosis has important implications to cancer. The increase in the expression of HIP in cancer cells renders them more resistant to apoptosis and may account, at least in part, for the resistance of these cells to anticancer drug-induced apoptosis. This has important implications for the treatment of cancer by chemotherapy. It would be interesting to correlate the sensitivity of tumors to chemotherapeutic agents and the levels of HIP expression. Also, one can envisage using antisense therapy or other ways to decrease HIP levels in tumors in conjunction with chemotherapy to render tumors more sensitive to apoptosis. In conclusion, we have demonstrated that HIP is an anti-apoptotic peptide and is involved in regulating apoptosis induced by anticancer drugs.


    Acknowledgments
 
This work was supported by the National Medical Research Council of Singapore (R185000029213) and NIH (HD25235).


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 

  1. Wang,Y., Cheong,D., Chan,S. and Hooi,S.C. (1999) Heparin/heparan sulfate interacting protein gene expression is up-regulated in human colorectal carcinoma and correlated with differentiation status and metastasis. Cancer Res., 59, 2989–2994.[Abstract/Free Full Text]
  2. de Nigris,F., Visconti,R., Cerutti,J., Califano,D., Mineo,A., Santoro,M., Santelli,G. and Fusco,A. (1998) Overexpression of the HIP gene coding for a heparin/heparan sulfate-binding protein in human thyroid carcinomas. Cancer Res., 58, 4745–4751.[Abstract]
  3. Liu,S., Hoke,D., Julian,J. and Carson,D.D. (1997) Heparin/heparan sulfate (HP/HS) interacting protein (HIP) supports cell attachment and selective, high affinity binding of HP/HS. J. Biol. Chem., 272, 25856–25862.[Abstract/Free Full Text]
  4. Liu,S., Julian,J. and Carson,D.D. (1998) A peptide sequence of heparin/heparan sulfate (HP/HS)-interacting protein supports selective, high affinity binding of HP/HS and cell attachment. J. Biol. Chem., 273, 9718–9726.[Abstract/Free Full Text]
  5. Iozzo,R.V. (1988) Cell surface heparan sulfate proteoglycan and the neoplastic phenotype. J. Cell Biochem., 37, 61–78.[ISI][Medline]
  6. Iozzo,R.V. (1988) Proteoglycans and neoplasia. Cancer Metast. Rev., 7, 39–50.[ISI][Medline]
  7. Bernfield,M., Gotte,M., Park,P.W., Reizes,O., Fitzgerald,M.L., Lincecum,J. and Zako,M. (1999) Functions of cell surface heparan sulfate proteoglycans. Annu. Rev. Biochem., 68, 729–777.[CrossRef][ISI][Medline]
  8. Kure,S., Yoshie,O. and Aso,H. (1987) Metastatic potential of murine B16 melanoma correlates with reduced surface heparan sulfate glycosaminoglycan. Jpn. J. Cancer Res., 78, 1238–1245.[ISI][Medline]
  9. Liu,S., Zhou,F., Hook,M. and Carson,D.D. (1997) A heparin-binding synthetic peptide of heparin/heparan sulfate-interacting protein modulates blood coagulation activities. Proc. Natl Acad. Sci. USA, 94, 1739–1744.[Abstract/Free Full Text]
  10. Ta,T.V., Baraniak,D., Julian,J., Korostoff,J., Carson,D.D. and Farach-Carson,M.C. (2002) Heparan sulfate interacting protein (HIP/L29) negatively regulates growth responses to basic fibroblast growth factor in gingival fibroblasts. J. Dent. Res., 81, 247–252.[Abstract/Free Full Text]
  11. Raff,M.C. (1992) Social controls on cell survival and cell death. Nature, 356, 397–400.[CrossRef][ISI][Medline]
  12. Rohde,L.H., Julian,J., Babaknia,A. and Carson,D.D. (1996) Cell surface expression of HIP, a novel heparin/heparan sulfate binding protein, of human uterine epithelial cells and cell lines. J. Biol. Chem., 271, 11824–11830.[Abstract/Free Full Text]
  13. Liu,J.J., Nilsson,A., Oredsson,S., Badmaev,V., Zhao,W.Z. and Duan,R.D. (2002) Boswellic acids trigger apoptosis via a pathway dependent on caspase-8 activation but independent on Fas/Fas ligand interaction in colon cancer HT-29 cells. Carcinogenesis, 23, 2087–2093.[Abstract/Free Full Text]
  14. Tan,S., Seow,T.K., Liang,R.C., Koh,S., Lee,C.P., Chung,M.C. and Hooi,S.C. (2002) Proteome analysis of butyrate-treated human colon cancer cells (HT-29). Int. J. Cancer, 98, 523–531.[CrossRef][ISI][Medline]
  15. Augenlicht,L.H., Mariadason,J.M., Wilson,A., Arango,D., Yang,W., Heerdt,B.G. and Velcich,A. (2002) Short chain fatty acids and colon cancer. J. Nutr., 132, 3804S–3808S.[Abstract/Free Full Text]
  16. Chai,F., Evdokiou,A., Young,G.P. and Zalewski,P.D. (2000) Involvement of p21 (Waf1/Cip1) and its cleavage by DEVD-caspase during apoptosis of colorectal cancer cells induced by butyrate. Carcinogenesis, 21, 7–14.[Abstract/Free Full Text]
  17. Kaufmann,S.H., Desnoyers,S., Ottaviano,Y., Davidson,N.E. and Poirier,G.G. (1993) Specific proteolytic cleavage of poly (ADP-ribose) polymerase: an early marker of chemotherapy-induced apoptosis. Cancer Res., 53, 3976–3985.[Abstract]
  18. Gerber,A., Bohne,M., Rasch,J., Struy,H., Ansorge,S. and Gollnick,H. (2000) Investigation of annexin V binding to lymphocytes after extracorporeal photoimmunotherapy as an early marker of apoptosis. Dermatology, 201, 111–117.[CrossRef][ISI][Medline]
  19. Bernhard,D., Ausserlechner,M.J., Tonko,M., Loffler,M., Hartmann,B.L., Csordas,A. and Kofler,R. (1999) Apoptosis induced by the histone deacetylase inhibitor sodium butyrate in human leukemic lymphoblasts. FASEB J., 13, 1991–2001.[Abstract/Free Full Text]
  20. Morris,E.J. and Geller,H.M. (1996) Induction of neuronal apoptosis by camptothecin, an inhibitor of DNA topoisomerase-I: evidence for cell cycle-independent toxicity. J. Cell. Biol., 134, 757–770.[Abstract]
  21. Wight,T.N., Kinsella,M.G. and Qwarnstrom,E.E. (1992) The role of proteoglycans in cell adhesion, migration and proliferation. Curr. Opin. Cell. Biol., 4, 793–801.[Medline]
  22. Ruoslahti,E. and Yamaguchi,Y. (1991) Proteoglycans as modulators of growth factor activities. Cell, 64, 867–869.[ISI][Medline]
Received June 17, 2003; revised January 5, 2004; accepted January 7, 2004.





This Article
Abstract
FREE Full Text (PDF)
All Versions of this Article:
25/6/873    most recent
bgh081v1
Alert me when this article is cited
Alert me if a correction is posted
Services
Email this article to a friend
Similar articles in this journal
Similar articles in ISI Web of Science
Similar articles in PubMed
Alert me to new issues of the journal
Add to My Personal Archive
Download to citation manager
Request Permissions
Google Scholar
Articles by Liu, J.-J.
Articles by Hooi, S. C.
PubMed
PubMed Citation
Articles by Liu, J.-J.
Articles by Hooi, S. C.