Cell experiment:

Sulfasalazine is dissolved in culture medium. SW620 cells are grown in Dulbecco’s modified Eagle medium, supplemented with 10% heat-inactivated FCS, 2 mmol/liter glutamine, and 1% (wt/vol) penicillin/streptomycin. SW620 cells are transfected with the 3xIgkBLuc reporter construct. After 18 h, cells are incubated with either medium alone or with sulfasalazine (0.1, 0.2, 0.5, 1, 2, 5 mM) before stimulation with TNFα, LPS, or PMA. Luciferase assay is performed[1].

Animal experiment:

Mice: Sulfasalazine is dissolved in 0.1 M NaOH, and then neutralized by titrating with 0.1 M HCl. U-87MG glioma cells are implanted into the cranium of a SCID mouse. After 7 days, animals are randomized into three groups of five animals each. One group receives 1 mL i.p. saline injections twice daily for 3 weeks. The two test groups receives 8 mg of sulfasalazine in 1 mL saline twice daily for 3 weeks. Tumor growth and animal health were monitored. After perfusion with 4% paraformaldehyde, mouse brains were collected, rinsed, and placed in 30% sucrose[3].

Sulfasalazine is a drug for the treatment of rheumatoid arthritis and ulcerative colitis. Sulfasalazine is reported to suppress NF-κB activity.

Treatment of SW620 colon cells with sulfasalazine inhibits TNFα-, LPS-, or phorbol ester-induced NFκB activation. NFκB-dependent transcription is inhibited by sulfasalazine at micro- to millimolar concentrations. TNFα-induced nuclear translocation of NFκB is prevented by sulfasalazine through inhibition of IκBα degradation[1]. Pre-incubation with 5 mM of sulfasalazine alone significantly increases basal mRNA expression of all pro-inflammatory cytokines with levels of IL-6 mRNA increased by 80-fold compared with vehicle control[2]. Once digested, sulfasalazine is cleaved into sulfapyridine and 5-aminosalicylic acid by colonic bacteria, and the latter, too, is reported to suppress NF-kappaB activity[3].

At low doses (0.25 mM), SAS is able to suppress glioma growth by over 60% compared to untreated controls[3].

References:
[1]. Wahl C, et al. Sulfasalazine: a potent and specific inhibitor of nuclear factor kappa B. J Clin Invest. 1998 Mar 1;101(5):1163-74.
[2]. Sykes L, et al. Sulfasalazine augments a pro-inflammatory response in interleukin-1β-stimulated amniocytes and myocytes. Immunology. 2015 Dec;146(4):630-44.
[3]. Chung WJ, et al. Sulfasalazine inhibits the growth of primary brain tumors independent of nuclear factor-kappaB. J Neurochem. 2009 Jul;110(1):182-93.