Biological Activity
px 12 is an inhibitor of thioredoxin-1 [1].thioredoxin-1 (trx-1) is a small redox protein with a conserved catalytic site and plays an important role in cells that includes the regulation of trans-activating activity and the dna binding of redox-sensitive transcription factors [1].in ht-29 human colon carcinoma cells and mcf-7 human breast cancer, px 12 prevented the hypoxia-induced increase in hif-1 protein. also, px 12 decreased inducible nitric oxide synthase, hif-1-trans-activating activity and vegf formation [2].in immunodeficient mice bearing ht-29 human colon xenografts, px 12 decreased the average tumor blood vessel permeability by 63% within 2 hours and returned to pretreatment values after 48 hours. px 12 reduced tumor-derived vegf and tumor after 24 hours. also, trx-1 showed a rapid decrease within 2 hours and maintained for 24 hours [1]. in mice bearing mcf-7 tumor xenografts, px 12 reduced hif-1ɑ and vegf protein levels [2]. in cancer patients, px-12 treatment significantly reduced the levels of trx-1 and vegf in plasma [3].
Biochem/physiol Actions
PX-12 inhibits the thioredoxin redox system and HIF-1a activity. PX 12 inhibits hypoxia-induced HIF-1a transcriptional activity (IC50 11 nM) and proliferation of HT29 and MCF-7 tumor cells (IC50 1.9 and 0.9 uM, respectively).
References
[1]. jordan bf, runquist m, raghunand n, et al. the thioredoxin-1 inhibitor 1-methylpropyl 2-imidazolyl disulfide (px-12) decreases vascular permeability in tumor xenografts monitored by dynamic contrast enhanced magnetic resonance imaging. clin cancer res, 2005, 11(2 pt 1): 529-536.
[2]. welsh sj, williams rr, birmingham a, et al. the thioredoxin redox inhibitors 1-methylpropyl 2-imidazolyl disulfide and pleurotin inhibit hypoxia-induced factor 1alpha and vascular endothelial growth factor formation. mol cancer ther, 2003, 2(3): 235-243.
[3]. baker af, dragovich t, tate wr, et al. the antitumor thioredoxin-1 inhibitor px-12 (1-methylpropyl 2-imidazolyl disulfide) decreases thioredoxin-1 and vegf levels in cancer patient plasma. j lab clin med, 2006, 147(2): 83-90.