AVN-944(VX-944) is a selective, noncompetitive inhibitor of the enzyme directed against human IMPDH with Ki of 6-10 nM for IMPDH1/IMPDH2.IC50 value: 6-10 nM (Ki) [1]Target: IMPDHin vitro: AVN-944 strikingly inhibit RNA synthesis within 2 h of exposure. Depletion of guanine nucleotides by MPA and AVN-944 also causes an early and near-complete reduction in levels of the 45S precursor rRNA synthesis and the concomitant translocation of nucleolar proteins including nucleolin, nucleophosmin, and nucleostemin from the nucleolus to the nucleoplasm [2]. AVN944 induced caspase-dependentand caspase-independent cell death in LNCaP, CWR22Rv1, and DU145 cells. AVN944 induced expression of p53-target proteins Bok, Bax and Noxa in androgen-responsive cell lines and suppressed expression of survivin in prostate cancer cells regardless of their androgen sensitivity. AVN944 also induced differentiation of androgen-independent prostate cancer cells as indicated by morphological changes and increased expression of genes coding for prostasomal proteins, keratins and other proteins, including tumor suppressor genes MIG-6 and NDRG1. AVN944-differentiated androgen-independent DU145 and PC-3 cells are sensitized to TRAIL-induced apoptosis as demonstrated by induction of caspases and PARP cleavage [3].
References:
[1]. Zimmermann AG, et al. Inosine-5'-monophosphate dehydrogenase: regulation of expression and role in cellular proliferation and T lymphocyte activation. Prog Nucleic Acid Res Mol Biol. 1998;61:181-209.
[2]. Huang M, et al. Guanine nucleotide depletion inhibits pre-ribosomal RNA synthesis and causes nucleolar disruption. Leuk Res. 2008 Jan;32(1):131-41.
[3]. Floryk D, et al. Antiproliferative effects of AVN944, a novel inosine 5-monophosphate dehydrogenase inhibitor, in prostate cancer cells. Int J Cancer. 2008 Nov 15;123(10):2294-302.