Tetraarsenic hexoxide demonstrates anticancer activity at least in part through suppression of NF-κB activity in SW620 human colon cancer cells

  • Authors:
    • Won Sup Lee
    • Jeong Won Yun
    • Arulkumar Nagappan
    • Hyeon Soo Park
    • Jing Nan Lu
    • Hye Jung Kim
    • Seong-Hwan Chang
    • Dong Chul Kim
    • Jeong-Hee Lee
    • Jin-Myung Jung
    • Soon Chan Hong
    • Woo Song Ha
    • Gonsup Kim
  • View Affiliations

  • Published online on: March 31, 2015     https://doi.org/10.3892/or.2015.3890
  • Pages: 2940-2946
Metrics: Total Views: 0 (Spandidos Publications: | PMC Statistics: )
Total PDF Downloads: 0 (Spandidos Publications: | PMC Statistics: )


Abstract

Tetraarsenic hexoxide (As4O6) has been used in Korean traditional medicine for the treatment of cancer since the late 1980's, and arsenic trioxide (As2O3) is currently used as a chemotherapeutic agent. Previous studies suggest that the As4O6-induced cell death pathway is different from that of As2O3 and its mechanism of anticancer activity remains unclear. Nuclear factor (NF)-κB is a well-known transcription factor involved in cell proliferation, invasion and metastasis. Hence, in the present study, we investigated the effects of As4O6 on NF-κB activity and NF-κB-regulated gene expression in vitro and in vivo. The cytotoxicity assay revealed that As4O6 inhibited the growth of SW620 cells in a dose-dependent manner, and the half maximal inhibitory concentration (IC50) was ~1 µM after a 48 h treatment. As4O6 suppressed NF-κB activation and suppressed inhibitory κBα (IκBα) phosphorylation stimulated by tumor necrosis factor (TNF). As4O6 also suppressed downstream NF-κB-regulated proteins involved in cancer anti-apoptosis, proliferation, invasion and metastasis. In addition, As4O6 marginally suppressed tumor growth and the anti-NF-κB activity was confirmed using an in vivo xenograft mouse model in which animals were injected with SW620 cells. The present study provides evidence that As4O6 has anticancer properties through suppression of NF-κB activity and NF-κB-mediated cellular responses.

Introduction

Colon cancer is one of the most common cancers in the world (1). Regarding treatment, surgical resection is frequently limited due to metastasis such as in most other cancers. Although several chemotherapeutic drugs are available for the treatment of metastatic lesions, the toxic effects are serious. Recently, with the advancement in science, the life-span has been increasing, and the elderly population with cancer is also increasing. However, these patients cannot tolerate the cytotoxic effects of chemotherapies. Therefore, new treatment strategies are required for elderly patients. Arsenic trioxide (As2O3) had been used in Chinese medicine for cancer treatment, and is now used as a standard treatment for refractory acute promyelocytic leukemia (2,3). Several clinical trials have been performed in certain types of solid cancers (4,5), yet they failed to prove clinical efficacy due to high toxicities (6,7). Tetraarsenic hexoxide (As4O6) has been used as a Korean folk remedy for the management of cancer since the late 1980’s and shows no serious toxicities. However, little research regarding the anticancer effects of As4O6 has been conducted even though previous studies have shown that the anticancer effects of As4O6 are more potent than those of As2O3 in human cancer cells in vitro, and that the signaling pathways of As4O6-induced cell death are different from those of As2O3 (8,9). We previously demonstrated that As4O6 has synergistic effects with tumor necrosis factor (TNF). TNF is known as a stimulator of nuclear factor (NF)-κB and NF-κB is a transcription factor closely linked to cell survival, proliferation and metastasis (10). In the present study, we explored the anticancer effects of As4O6 with special focus on the NF-κB pathway, on NF-κB-regulated gene products and on NF-κB-mediated cellular responses.

Materials and methods

Cells and reagents

SW620 human colon cancer cells purchased from the American Type Culture Collection (Rockville, MD, USA) were cultured in RPMI-1640 medium (Invitrogen Corp., Carlsbad, CA, USA) supplemented with 10% (v/v) fetal bovine serum (FBS) (Gibco-BRL, Grand Island, NY, USA), 1 mM L-glutamine, 100 U/ml penicillin and 100 μg/ml streptomycin at 37° C in a humidified atmosphere of 95% air and 5% CO2. As4O6 was provided by the Chonjisan Institute (Seoul, Korea). Antibodies against NF-κB (p65), cyclin D1, Bcl-2, Bcl-xL, XIAP, cIAP-1, cIAP-2, MMP-2, MMP-9, VEGF, p-NF-κB, transglutaminase 2 (TG-2), Ki-67 and CD34 were purchased from Santa Cruz Biotechnology, Inc. (Santa Cruz, CA, USA). An antibody against β-actin was from Sigma (Beverly, MA, USA). Peroxidase-labeled donkey anti-rabbit and sheep anti-mouse immunoglobulins, and an enhanced chemiluminescence (ECL) kit were purchased from Amersham (Arlington Heights, IL, USA). All other chemicals not specifically cited here were purchased from Sigma Chemical Co. (St. Louis, MO, USA). All of these solutions were stored at −20° C. Stock solutions of 4′, 6-diamidino-2-phenylindole (DAPI) (100 μg/ml) and propidium iodide (PI; 1 mg/ml) were prepared in phosphate-buffered saline (PBS).

Cell viability assay

For the cell viability assay, the cells were seeded onto 24-well plates at a concentration of 5×105 cells/ml, and then treated with the indicated concentration of As4O6 for 24 or 48 h. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) (0.5 mg/ml) was subsequently added to each well. After 3 h of additional incubation, 100 μl of a solution containing 10% SDS (pH 4.8) plus 0.01 N HCl was added to dissolve the crystals. The absorption values at 570 nm were determined with an ELISA plate reader.

Western blotting

Total cell lysates were obtained using lysis buffer containing 0.5% SDS, 1% NP-40, 1% sodium deoxycholate, 150 mM NaCl, 50 mM Tris-Cl (pH 7.5) and protease inhibitors. The concentrations of cell lysate proteins were determined by the Bradford protein assay (Bio-Rad Laboratories, Richmond, CA, USA) using bovine serum albumin as the standard. To determine the protein expression of NF-κB in the cytoplasm and the nuclei, we prepared separate extracts. The cells were washed with ice-cold PBS (pH 7.4) and lysed in buffer A [10 mM HEPES (pH 7.9), 1.5 mM MgCl2, 0.5 mM dithiothreitol (DTT), 5 μM leupeptin, 2 μM pepstatin A, 1 μM aprotinin and 20 μM phenylmethylsulfonyl fluoride] by repeated freezing and thawing. Nuclear and cytoplasmic fractions were separated by centrifugation at 1,000 × g for 20 min. The cytoplasmic extract (supernatant) was obtained. The pellets were washed with buffer A, and resuspended in buffer B [10 mM Tris-Cl (pH 7.5), 0.5% deoxycholate, 1% NP-40, 5 mM EDTA, 0.5 mM DTT, 5 μM leupeptin, 2 μM pepstatin A, 1 μM aprotinin and 20 μM phenylmethylsulfonyl fluoride]. The suspension was agitated for 30 min at 4° C and centrifuged at 10,000 × g for 20 min. The supernatant fraction containing nuclear proteins was collected. Molecular mass markers for proteins were obtained from Pharmacia Biotech (Saclay, France). Thirty micrograms of the lysate proteins were resolved by electrophoresis, electrotransferred to polyvinylidene difluoride membranes (Millipore, Bedford, MA, USA), and then incubated with primary antibodies followed by a secondary antibody conjugated to peroxidase. Blots were developed with an ECL detection system.

Immunocytochemistry

The cells were placed on coverslips coated with poly-L-lysine (1 mg/ml) in 6-well plates. They were fixed in 4% paraformaldehyde for 10 min followed by 1. 0 % H 2O2/0.1 M PBS treatment for 30 min after washing twice in PBS. Then, cells were treated with 0.3% Triton/0.1 M PBS for 5 min and then washed twice in buffered saline. They were incubated in 5% serum solution for 30 min at room temperature and then serum solution was removed with suction. The cells were incubated in buffered saline with a 1:50 dilution of primary antibodies for p65 NF-κB (Santa Cruz Biotechnology, Inc.) for 2 h and then washed in buffered saline three times for 10 min each at room temperature. They were incubated in buffered saline with a 1:250 dilution of biotinylated secondary antibodies (Vector Laboratories, Burlingame, CA, USA). Positive staining was visualized with diaminobenzidine, followed by a light hematoxylin counter-staining.

Transfection

NF-κB-luciferase constructs (consensus NF-κB binding sequence was cloned into the pGL3 basic luciferase expression vector) were kindly provided by Dr G. Koretzky (University of Pennsylvania). Transient transfection was performed using Lipofectamine (Gibco-BRL) according to the manufacturer’s protocol.

Luciferase assay

After experimental treatments, the cells were washed twice with cold PBS, lysed in a passive lysis buffer provided in the Dual-Luciferase kit (Promega, Madison, WI, USA), and assayed for luciferase activity using a TD-20/20 luminometer (Turner Designs, Sunnyvale, CA, USA) according to the manufacturer’s protocol. Data are presented as a ratio between firefly and Renilla luciferase activities.

Generation of xenograft tumors and immunohistochemical staining

All animal procedures were performed in accordance with a protocol approved by the Ethics Committee for Animal Experimentation, Gyeongsang National University. We followed animal science guidelines for animal experimentation. Xenograft tumors were generated by subcutaneous injection of SW620 cells, as described elsewhere (11). Briefly, nude mice were injected in a single dorsal flank site with 5×107 SW620 cells (n=12 mice) in 100 μl of PBS. Injection of these cells into nude mice induced exponentially growing tumors. When tumors reached a volume of 50–100 mm3 (termed day 0 for our experiments), the mice were treated intraperitoneally with vehicle (1 μl of normal saline) or As4O6 at 5 mg/kg once a day for 12 days. Tumor size was measured every 3–4 days, and tumor growth was quantified by measuring the tumors in two dimensions. Volumes were calculated by the formula: 0.5 × a × b, where a and b are the longest and the greatest perpendicular diameters, respectively. Tumor volumes were expressed as the mean and 95% confidence interval (CI) and expressed as relative change vs. time. Histopathologic evidence of pulmonary toxicity (i.e., edema or inflammation of the bronchial epithelium and alveoli), inflammation or injury in other organs, such as liver, and kidney were evaluated by a pathologist. Tumors were fixed in 10% buffered formalin, embedded in paraffin, and sectioned for hematoxylin and eosin (H&E) and immunohistochemical staining. Immunohistochemical staining for p-NF-κB, TG, Ki-67 and tumor vessel density was performed as previously described (12).

Statistical analysis

Each experiment was performed in triplicate. The results are expressed as means ± SD. Significant differences were determined using the one-way ANOVA with post-hoc Neuman-Keuls test in the case of at least three treatment groups and Student’s t-test for two group comparison. Statistical significance was defined as P<0.05.

Results

As4O6 suppresses cell proliferation of SW620 human colon cancer cells in a dose-dependent manner

To investigate the antitumor activity of As4O6 in SW620 cells, the cells were treated for 24 and 48 h with various concentrations of As4O6 (0.1–5 μM), and the cell growth was assessed by MTT assay. The MTT assay revealed that As4O6 inhibited the growth of SW620 cells in a dose-dependent manner at 24 and 48 h. As4O6 had a strong inhibitory effect after 48 h of treatment and the half maximal inhibitory concentration (IC50) was ~1 μM (Fig. 1A). Next, we assessed the changes in cellular morphology of the As4O6-treated cells under microscopy. The light microscopy results revealed that cell shrinkage and cytoplasmic blebs were observed after 24 and 48 h of incubation (Fig. 1B).

As4O6 suppresses NF-κB activity at least in part through inhibition of IκBα phosphorylation

To determine whether As4O6 inhibits NF-κB activity of SW620 cells, we used western blotting, immunohistocytochemistry and luciferase assay. Under resting conditions, NF-κB mostly consists of a heterotrimer of p50, p65 and inhibitory κBα (IκBα) in the cytoplasm; when activated, the heterodimer of p50 and p65 is translocated into the nucleus after separating from p-IκBα. Hence, we performed western blot analysis, which revealed that As4O6 reduced both the translocation of NF-κB into the nucleus and the levels of NF-κB in the cytoplasm (Fig. 2A). One advantage of immunohistochemistry is the ability to confirm NF-κB (p65) translocation into the nucleus on activation. As expected, TNF enhanced the NF-κB translocation into the nucleus and As4O6 inhibited the TNF-induced NF-κB activation (Fig. 2B). To confirm the effects of As4O6 on NF-κB activity, we performed a luciferase assay. As shown in Fig. 2C, the NF-κB gene was successfully transfected into the cells and the NF-κB-luciferase activity was augmented by TNF The NF-κB-luciferase activity induced by TNF was inhibited by As4O6 (Fig. 2C). As mentioned, NF-κB activation is required for the degradation of IκBα through phosphorylation by kinases. We also tested whether As4O6 suppressed TNF-induced phosphorylation of IκBα. Western blot analysis revealed that As4O6 prevented TNF-induced IκBα phosphorylation (Fig. 2D). This result suggested that As4O6 suppressed NF-κB activity at least in part through inhibition of IκBα phosphorylation.

As4O6 suppresses NF-κB-regulated proteins involved in anti-apoptosis, proliferation, invasion and angiogenesis

NF-κB activation leads to activation of several genes involved in anti-apoptosis, proliferation, invasion and angiogenesis in cancer. NF-κB regulates expression of anti-apoptotic proteins (c-IAP1/2, XIAP and Bcl-xL) (13), cyclin D1 for cell proliferation (14), MMP-2, MMP-9 for invasion and VEGF for angiogenesis of cancer (13,15). Hence, we investigated the effect of As4O6 on these molecules. Western blot analysis revealed that As4O6 suppressed the protein expression of XIAP, Bcl-2, Bcl-xL, cIAP-1, cyclin D1, MMP-2, MMP-9 and VEGF in a dose-and time-dependent manner (Fig. 3). These findings revealed that As4O6 suppressed the NF-κB-mediated cellular responses regarding cancer apoptosis, proliferation, invasion and angiogenesis in the SW620 cells.

As4O6 marginally suppresses the tumor growth of SW620 cells

Next, we evaluated the effect of As4O6 treatment on the growth of SW620 cells (Fig. 4). Tumor growth was marginally suppressed by As4O6 treatment throughout the 12-day treatment regimen, indicating the potent therapeutic efficacy of As4O6 in SW620 cancer cells (Fig. 4A). The volume of the control SW620 xenografts was 798 mm3 and that of the xenografts treated with As4O6 at 5 mg/kg was 115.9 mm3 (difference, 682.1 mm3; 95% CI, 480.4–883.9 mm3; P<0.001). Also, there were no significant difference in body weight between the control and treatment groups (Fig. 4B).

As4O6 suppresses NF-κB activity and NF-κB-mediated cellular phenotype such as cancer proliferation and angiogenesis in the in vivo xenograft mouse model

We further investigated the in vivo effect of As4O6 treatment on NF-κB activity and NF-κB-regulated proteins in the SW620 xenograft tumors. Immunohistochemical studies revealed that the expression of p-NF-κB in the tumors from the As4O6-treated mice was lower than that in the control tumors from the untreated mice (Fig. 5). Here, we also tested TG-2 since TG-2 expression has a good correlation with NF-κB activity (16), and a difference in p-NF-κB expression is not easily observed. The result indicated that As4O6 significantly suppressed TG-2 expression. In addition As4O6 also clearly suppressed CD34, a protein which is involved in angiogenesis and Ki-67, a nuclear protein that is associated with cellular proliferation. These findings were consistent with p-NF-κB expression and suggest that As4O6 may suppress NF-κB activity and NF-κB-regulated cellular phenotype.

Discussion

The present study was designed to investigate the anticancer effects of As4O6 with special focus on the NF-κB pathway, and NF-κB-regulated gene products, in in vitro and in vivo models. We found that As4O6 inhibited the growth of SW620 cells in a dose-dependent manner at 24 and 48 h. Furthermore, As4O6 inhibited NF-κB activity and NF-κB-regulated proteins involved in anti-apoptosis, cell proliferation, invasion and angiogenesis. Even though this finding is novel for As4O6, there is previous supporting evidence showing that arsenic trioxide (As2O3) suppresses NF-κB-mediated cellular activities (17). NF-κB is a well-known transcription factor involved in cancer proliferation, invasion, metastasis and drug resistance. We found that As4O6 suppressed MMP-2 and MMP-9 activity. MMP-2 and MMP-9 are key molecules in cancer cell invasion (18,19) which have been used as targets for drug development against cancer invasion (20). We also found that As4O6 suppressed cyclin D1 which is associated with cancer cell proliferation (13,14), and XIAP, Bcl-2, Bcl-xL and cIAP-1 that are involved in cancer cell survival and drug resistance (13). In addition, the role of VEGF in the angiogenesis of cancer is well known (21). All of these gene products are known to be regulated by NF-κB (13,15). Here, we used TNF to clearly demonstrate that As4O6 inhibits NF-κB. Plasma TNF is usually increased in patients with advanced and metastatic cancers (22). The pathophysiological relevance between TNF and NF-κB activation in advanced and metastatic cancers suggests that the use of TNF is also similar to the cancer environment in the human body. IκBα is the best-studied and a major IκB protein of the IκB family. When activated by signals, the IκB kinase phosphorylates two serine residues located in an IκBα regulatory domain. When IκBα is phosphorylated at serines 32 and 36, IκBα is degraded by ubiquitination (23). Here, we found that As4O6 suppressed phosphorylation of IκBα induced by TNF. This finding suggests that the anti-NF-κB activities of As4O6 are contributed to suppression of IκBα phosphorylation. In addition, we demonstrated that As4O6 inhibited NF-κB activity in an in vivo animal model even though the anticancer effects were marginal. One weak point is that although As4O6 suppressed the whole expression of NF-κB (Fig. 2A), we could not exactly elucidate the mechanisms. We also found that As4O6 suppressed the whole expression of NF-κB (data not shown). We need to further investigate this mechanism.

In conclusion, the present study demonstrated that As4O6 exerts anticancer effects by suppressing NF-κB and NF-κB-regulated genes involved in anti-apoptosis, proliferation, invasion and angiogenesis in cancer (Fig. 6). The present study provides evidence that As4O6 may have anticancer effects on human colon cancer.

Acknowledgments

This study was supported by a grant from the National Research Foundation of Korea (NRF) funded by the Korea government (MEST) (no. 2014-012154).

References

1 

El-Serag HB and Mason AC: Rising incidence of hepatocellular carcinoma in the United States. N Engl J Med. 340:745–750. 1999. View Article : Google Scholar : PubMed/NCBI

2 

Shen ZX, Chen GQ, Ni JH, Li XS, Xiong SM, Qiu QY, Zhu J, Tang W, Sun GL, Yang KQ, et al: use of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL). II Clinical efficacy and pharmacokinetics in relapsed patients. Blood. 89:3354–3360. 1997.PubMed/NCBI

3 

Niu C, Yan H, Yu T, Sun HP, Liu JX, Li XS, Wu W, Zhang FQ, Chen Y, Zhou L, et al: Studies on treatment of acute promyelocytic leukemia with arsenic trioxide: Remission induction, follow-up, and molecular monitoring in 11 newly diagnosed and 47 relapsed acute promyelocytic leukemia patients. Blood. 94:3315–3324. 1999.PubMed/NCBI

4 

Munshi NC, Tricot G, Desikan R, Badros A, Zangari M, Toor A, Morris C, Anaissie E and Barlogie B: Clinical activity of arsenic trioxide for the treatment of multiple myeloma. Leukemia. 16:1835–1837. 2002. View Article : Google Scholar : PubMed/NCBI

5 

Lin YC, Li DR and Lin W: Relationship between radiotherapy enhancing effect of arsenic trioxide and the proliferation and apoptosis of related protein in nasopharyngeal carcinoma patients. Zhongguo Zhong Xi Yi Jie He Za Zhi. 27:704–707. 2007.In Chinese. PubMed/NCBI

6 

Welch JS, Klco JM, Gao F, Procknow E, Uy GL, Stockerl-Goldstein KE, Abboud CN, Westervelt P, DiPersio JF, Hassan A, et al: Combination decitabine, arsenic trioxide, and ascorbic acid for the treatment of myelodysplastic syndrome and acute myeloid leukemia: A phase I study. Am J Hematol. 86:796–800. 2011. View Article : Google Scholar : PubMed/NCBI

7 

Beer TM, Tangen CM, Nichols CR, Margolin KA, Dreicer R, Stephenson WT, Quinn DI, Raghavan D and Crawford ED: Southwest Oncology Group phase II study of arsenic trioxide in patients with refractory germ cell malignancies. Cancer. 106:2624–2629. 2006. View Article : Google Scholar : PubMed/NCBI

8 

Chang HS, Bae SM, Kim YW, Kwak SY, Min HJ, Bae IJ, Lee YJ, Shin JC, Kim CK and Ahn WS: Comparison of diarsenic oxide and tetraarsenic oxide on anticancer effects: Relation to the apoptosis molecular pathway. Int J Oncol. 30:1129–1135. 2007.PubMed/NCBI

9 

Han MH, Lee WS, Lu JN, Yun JW, Kim G, Jung JM, Kim GY, Lee SJ, Kim WJ and Choi YH: Tetraarsenic hexoxide induces Beclin-1-induced autophagic cell death as well as caspase-dependent apoptosis in u937 human leukemic cells. Evid Based Complement Alternat Med. 2012:2014142012. View Article : Google Scholar

10 

Guttridge DC, Albanese C, Reuther JY, Pestell RG and Baldwin AS Jr: NF-kappaB controls cell growth and differentiation through transcriptional regulation of cyclin D1. Mol Cell Biol. 19:5785–5799. 1999.PubMed/NCBI

11 

Lee HY, Moon H, Chun KH, Chang YS, Hassan K, Ji L, Lotan R, Khuri FR and Hong WK: Effects of insulin-like growth factor binding protein-3 and farnesyltransferase inhibitor SCH66336 on Akt expression and apoptosis in non-small-cell lung cancer cells. J Natl Cancer Inst. 96:1536–1548. 2004. View Article : Google Scholar : PubMed/NCBI

12 

Jang JS, Lee WS, Lee JS, Kim HW, Ko GH and Ha WS: The expression of thymidine phosphorylase in cancer-infiltrating inflammatory cells in stomach cancer. J Korean Med Sci. 22(Suppl 22): S109–S114. 2007. View Article : Google Scholar : PubMed/NCBI

13 

Aggarwal BB: Nuclear factor-kappaB: The enemy within. Cancer Cell. 6:203–208. 2004. View Article : Google Scholar : PubMed/NCBI

14 

Motokura T and Arnold A: PRAD1/cyclin D1 proto-oncogene: Genomic organization, 5′ DNA sequence, and sequence of a tumor-specific rearrangement breakpoint. Genes Chromosomes Cancer. 7:89–95. 1993. View Article : Google Scholar : PubMed/NCBI

15 

Gilmore TD: Introduction to NF-kappaB: Players, pathways, perspectives. Oncogene. 25:6680–6684. 2006. View Article : Google Scholar : PubMed/NCBI

16 

Kim DS, Park SS, Nam BH, Kim IH and Kim SY: Reversal of drug resistance in breast cancer cells by transglutaminase 2 inhibition and nuclear factor-kappaB inactivation. Cancer Res. 66:10936–10943. 2006. View Article : Google Scholar : PubMed/NCBI

17 

Kerbauy DM, Lesnikov V, Abbasi N, Seal S, Scott B and Deeg HJ: NF-kappaB and FLIP in arsenic trioxide (ATO)-induced apoptosis in myelodysplastic syndromes (MDSs). Blood. 106:3917–3925. 2005. View Article : Google Scholar : PubMed/NCBI

18 

Davies B, Waxman J, Wasan H, Abel P, Williams G, Krausz T, Neal D, Thomas D, Hanby A and Balkwill F: Levels of matrix metalloproteases in bladder cancer correlate with tumor grade and invasion. Cancer Res. 53:5365–5369. 1993.PubMed/NCBI

19 

Bogenrieder T and Herlyn M: Axis of evil: Molecular mechanisms of cancer metastasis. Oncogene. 22:6524–6536. 2003. View Article : Google Scholar : PubMed/NCBI

20 

Vihinen P and Kähäri VM: Matrix metalloproteinases in cancer: Prognostic markers and therapeutic targets. Int J Cancer. 99:157–166. 2002. View Article : Google Scholar : PubMed/NCBI

21 

Nishida N, Yano H, Nishida T, Kamura T and Kojiro M: Angiogenesis in cancer. Vasc Health Risk Manag. 2:213–219. 2006. View Article : Google Scholar

22 

Correia M, Cravo M, Marques-Vidal P, Grimble R, Dias-Pereira A, Faias S and Nobre-Leitão C: Serum concentrations of TNF-alpha as a surrogate marker for malnutrition and worse quality of life in patients with gastric cancer. Clin Nutr. 26:728–735. 2007. View Article : Google Scholar : PubMed/NCBI

23 

Chen ZJ, Parent L and Maniatis T: Site-specific phosphorylation of IkappaBalpha by a novel ubiquitination-dependent protein kinase activity. Cell. 84:853–862. 1996. View Article : Google Scholar : PubMed/NCBI

Related Articles

Journal Cover

June-2015
Volume 33 Issue 6

Print ISSN: 1021-335X
Online ISSN:1791-2431

Sign up for eToc alerts

Recommend to Library

Copy and paste a formatted citation
x
Spandidos Publications style
Lee WS, Yun JW, Nagappan A, Park HS, Lu JN, Kim HJ, Chang S, Kim DC, Lee J, Jung J, Jung J, et al: Tetraarsenic hexoxide demonstrates anticancer activity at least in part through suppression of NF-κB activity in SW620 human colon cancer cells. Oncol Rep 33: 2940-2946, 2015
APA
Lee, W.S., Yun, J.W., Nagappan, A., Park, H.S., Lu, J.N., Kim, H.J. ... Kim, G. (2015). Tetraarsenic hexoxide demonstrates anticancer activity at least in part through suppression of NF-κB activity in SW620 human colon cancer cells. Oncology Reports, 33, 2940-2946. https://doi.org/10.3892/or.2015.3890
MLA
Lee, W. S., Yun, J. W., Nagappan, A., Park, H. S., Lu, J. N., Kim, H. J., Chang, S., Kim, D. C., Lee, J., Jung, J., Hong, S. C., Ha, W. S., Kim, G."Tetraarsenic hexoxide demonstrates anticancer activity at least in part through suppression of NF-κB activity in SW620 human colon cancer cells". Oncology Reports 33.6 (2015): 2940-2946.
Chicago
Lee, W. S., Yun, J. W., Nagappan, A., Park, H. S., Lu, J. N., Kim, H. J., Chang, S., Kim, D. C., Lee, J., Jung, J., Hong, S. C., Ha, W. S., Kim, G."Tetraarsenic hexoxide demonstrates anticancer activity at least in part through suppression of NF-κB activity in SW620 human colon cancer cells". Oncology Reports 33, no. 6 (2015): 2940-2946. https://doi.org/10.3892/or.2015.3890