ACTIBIND, an actin‐binding fungal T₂‐RNase with antiangiogenic and anticarcinogenic characteristics

Abstract

In view of the complexity of surface photografting polymerization of vinyl acetate/maleic anhydride (VAC/MAH) binary monomer systems, a novel method was adopted in the present article to obtain insight into the relevant grafting copolymerization mechanism. This method includes two steps: semibenzopinacol dormant groups were first introduced onto LDPE film by UV‐irradiation and then thermally reactivated to produce LDPE macromolecular free radicals, which initiated the grafting copolymerization of VAC and MAH. It was demonstrated that, in the first step, the solvent used to introduce benzophenone (BP) to LDPE film largely affected the subsequent grafting copolymerization, which was closely related to the affinity of the solvent toward the substrate. The monomer feed composition had considerable influence on both the grafting and nongrafting copolymerization; however, the maximum copolymerization rates did not appear in the polymerization system with [VAC]/[MAH] being 1 : 1, but, in the system with a bit more VAC than MAH, as the total monomer concentration was raised, the maximum copolymerization rates tended to appear in the system with [VAC] equal to [MAH]. The relationship between the total copolymerization rate (RP) and monomer concentration was determined to be LnRP ∝ [VAC + MAH]1.83. All of these results indicated that both charge transfer (CT) complex formed by VAC and MAH and free monomers took part in grafting copolymerization. This feature differentiated the surface grafting copolymerization of VAC/MAH from the well‐studied thermally induced alternating copolymerization of VAC/MAH. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006

ACTIBIND, a T2 RNase, Competes with Angiogenin and Inhibits Human Melanoma Growth, Angiogenesis, and Metastasis

“…We extracted a T 2 RNase from the fungus Aspergillus niger and established that it inhibits the elongation and alters the orientation of pollen tubes in plants by interfering with the intracellular actin network; thus, we named it ACTIBIND (9). More recently, we reported that ACTIBIND exerted preventive and therapeutic effects in two different models of colorectal cancer (10). Our results indicated that ACTIBIND may function as an antiangiogenic and antivascular drug, targeting tumor-associated blood vessels (10).…”

“…More recently, we reported that ACTIBIND exerted preventive and therapeutic effects in two different models of colorectal cancer (10). Our results indicated that ACTIBIND may function as an antiangiogenic and antivascular drug, targeting tumor-associated blood vessels (10). We postulated that ACTIBIND might exert its antiangiogenic activities through inhibition of angiogenin.…”

“…Our previous data suggested that ACTIBIND possesses antiangiogenic properties (10). To confirm and further establish its antiangiogenic effects, we did an in vivo Gelfoam sponge angiogenic assay as previously described (23) using either angiogenin or bFGF as angiogenic stimulators.…”

“…Thus, researchers have proposed biological functions for these enzymes other than the processing of cellular RNA. Our group was the first to isolate and characterize a T 2 RNase with antitumorigenic properties (9,10). We extracted a T 2 RNase from the fungus Aspergillus niger and established that it inhibits the elongation and alters the orientation of pollen tubes in plants by interfering with the intracellular actin network; thus, we named it ACTIBIND (9).…”

Isolation of Pollen-expressed Actin as a Candidate Protein Interacting with S-RNase in Prunus avium L.

“…Actin was reported to bind to some of the T2/S-type RNase family proteins, such as human RNASET2 and Aspergillus ACTIBIND. E3 ligase, such as SLF in Plantaginaceae and SBP1 and SLF in Solananaceae, were also reported to bind to S-RNase (Hua and Kao, 2006;O'Brien et al, 2004;Qiao et al, 2004;Roiz et al, 2006;Sims and Ordanic, 2001;Smirnoff et al, 2006). Although E3 ligase homologs can be very good candidates for general inhibitors of S-RNase, we selected the actin homolog for further characterization in this study and left E3 ligase homologs for future studies, because we suspected that S-RNase may exert its cytotoxic effects through its actin-binding ability.…”