A Novel AURKA Mutant-Induced Early-Onset Severe Hepatocarcinogenesis Greater than Wild-Type via Activating Different Pathways in Zebrafish.

Aurora A kinase (AURKA) is an important regulator in mitotic progression and is overexpressed frequently in human cancers, including hepatocellular carcinoma (HCC). Many AURKA mutations were identified in cancer patients. Overexpressing wild-type Aurka developed a low incidence of hepatic tumors after long latency in mice. However, none of the AURKA mutant animal models have ever been described. The mechanism of mutant AURKA-mediated hepatocarcinogenesis is still unclear. A novel AURKA mutation with a.a.352 Valine to Isoleucine (V352I) was identified from clinical specimens. By using liver-specific transgenic fish overexpressing both the mutant and wild-type AURKA, the AURKA(V352I)-induced hepatocarcinogenesis was earlier and much more severe than wild-type AURKA. Although an increase of the expression of lipogenic enzyme and lipogenic factor was observed in both AURKA(V352I) and AURKA(WT) transgenic fish, AURKA(V352I) has a greater probability to promote fibrosis at 3 months compared to AURKA(WT). Furthermore, the expression levels of cell cycle/proliferation markers were higher in the AURKA(V352I) mutant than AURKA(WT) in transgenic fish, implying that the AURKA(V352I) mutant may accelerate HCC progression. Moreover, we found that the AURKA(V352I) mutant activates AKT signaling and increases nuclear ß-catenin, but AURKA(WT) only activates membrane form ß-catenin, which may account for the differences. In this study, we provide a new insight, that the AURKA(V352I) mutation contributes to early onset hepatocarcinogenesis, possibly through activation of different pathways than AURKA(WT). This transgenic fish may serve as a drug-screening platform for potential precision medicine therapeutics.

Identification of Novel Anti-Liver Cancer Small Molecules with Better Therapeutic Index than Sorafenib via Zebrafish Drug Screening Platform.

Hepatocellular carcinoma (HCC) ranks as the fourth leading cause of cancer-related deaths worldwide. Sorafenib was the only U.S. Food and Drug Administration (FDA) approved drug for treating advanced HCC until recently, so development of new target therapy is urgently needed. In this study, we established a zebrafish drug screening platform and compared the therapeutic effects of two multiple tyrosine kinase inhibitors, 419S1 and 420S1, with Sorafenib. All three compounds exhibited anti-angiogenesis abilities in immersed fli1:EGFP transgenic embryos and the half inhibition concentration (IC50) was determined. 419S1 exhibited lower hepatoxicity and embryonic toxicity than 420S1 and Sorafenib, and the half lethal concentration (LC50) was determined. The therapeutic index (LC50/IC50) for 419S1 was much higher than for Sorafenib and 420S1. The compounds were either injected retro-orbitally or by oral gavage to adult transgenic zebrafish with HCC. The compounds not only rescued the pathological feature, but also reversed the expression levels of cell-cycle-related genes and protein levels of a proliferation marker. Using a patient-derived-xenograft assay, we found that the effectiveness of 419S1 and 420S1 in preventing liver cancer proliferation is better than that of Sorafenib. With integrated efforts and the advantage of the zebrafish platform, we can find more effective and safe drugs for HCC treatment and screen for personalized medicine.

Density functional studies on palladium-catalyzed Suzuki-Miyaura cross-coupling reactions assisted by N- or P-chelating ligands.

DFT studies with the B3LYP functional have been carried out on the Suzuki-Miyaura cross-coupling reactions of phenyl chloride and phenylboronic acid catalyzed by palladium complexes with N- or P-chelating ligands. The full catalytic cycle, from the addition of reactants to the catalyst to the release of the cross-coupled product from the complexed intermediate, has been examined. The stages within the cycle, such as oxidative addition, transmetalation, and reductive elimination, were validated by linking the mechanistically relevant intermediates and transition states. Various derivatives of diimine, diphosphine, and diamine were considered as potential model ligands. The catalytic reaction employing diimine as the chelating ligand has been verified as the one with the most energetically feasible route.

Experimental and DFT study of the tautomeric behavior of cobalt-containing secondary phosphine oxides.

New cobalt-containing secondary phosphine oxides [(mu-PPh(2)CH(2)PPh(2))Co(2)(CO)(4){mu,eta-PhC[triple chemical bond]CP(==O)(H)(R)}] (8 a: R=tBu; 8 b: R=Ph) were prepared by reaction of secondary phosphine oxides PhC[triple chemical bond]CP- (==O)(H)(R) (6 a: R=tBu; 6 b: R=Ph) with dppm-bridged dicobalt complex [(mu-PPh(2)CH(2)PPh(2))Co(2)(CO)(6)] (2). The molecular structures of 8 a and 8 b were determined by single-crystal X-ray diffraction. Although palladium-catalyzed Heck reactions employing 8 b as ligand gave satisfying results, 8 a performed poorly in the same reaction. Judging from these results, a tautomeric equilibrium between 8 b and its isomeric form [(mu-PPh(2)CH(2)PPh(2))Co(2)(CO)(4){mu,eta-PhC[triple chemical bond]CP(OH)(Ph)}] 8 b' indeed takes place, but it is unlikely between 8 a and [(mu-PPh(2)CH(2)PPh(2))Co(2)(CO)(4){mu,eta-PhC[triple chemical bond]CP(OH)(tBu)}] (8 a'). The DFT studies demonstrated that reasonable activation energies for the tautomeric conversions can be achieved only via a bimolecular pathway. Since a tBu group is much larger than a Ph group, the conversion is presumably only feasible in the case of 8 bright harpoon over left harpoon8 b', but not in the case of 8 aright harpoon over left harpoon8 a'. Another cobalt-containing phosphine, namely, [(mu-PPh(2)CH(2)PPh(2))Co(2)(CO)(4){mu,eta-PhC[triple chemical bond]CP(NEt(2))(tBu)}] (7 a), and its oxidation product [(mu-PPh(2)CH(2)PPh(2))Co(2)(CO)(4){mu,eta-PhC[triple chemical bond]CP(==O)(NEt(2))(tBu)}] 7 a' were prepared from the reaction of PhC[triple chemical bond]CP(NEt(2))(tBu) (5 a) with 2. The molecular structures of 7 a and 7 a' were determined by single-crystal X-ray diffraction. The phosphorus atom is surrounded by substituents in a tetrahedral environment. A P--N single bond (1.676(3) A) is observed in the molecular structure of 7 a. Heck reactions employing 7 a/Pd(OAc)(2) as catalyst system exhibited efficiency comparable to that of 8 a/Pd(OAc)(2).

Oxygen insertion in a carbon-phosphorus bond of the phenylethynyl-di-(tert-butyl)-phosphine bridged dicobalt complex: exploring the nature of oxygen migration using DFT.

In the process of isolation under aerobic conditions phenylethynyl-di-(tert-butyl)-phosphine bridged dicobalt complex [(micro-PPh(2)CH(2)PPh(2))Co2(CO)4(micro,eta-PhC[triple bond]CP(t-Bu)2)] 4a underwent a partial oxidation. The identity of the oxidized product, [(micro-PPh(2)CH(2)PPh(2))Co2(CO)4(micro,eta-PhC[triple bond]C-O-P([double bond]O)(t-Bu)2)] 5, was established by spectroscopic means as well as the single-crystal X-ray diffraction method. This is the first crystallographic evidence that unambiguously supports the formation of an organometallic version of a phosphinate ester. The mechanism for the formation of 5 from 4a was proposed, and its validity was examined by DFT means. For the purpose of comparison, a similar mechanism illustrating the transformation of PhC[triple bond]CP(t-Bu)2 1O into PhC[triple bond]C-O-P([double bond]O)(t-Bu)2 5O, the organic counterpart of 5, was examined by the same method. It was found that the metal fragment is indeed capable of assisting the oxidation process by lowering the activation energy, although the effect is small. The impact of the presence of an electron-withdrawing substituent such as a fluorine atom in the alkynylphosphine was also investigated. Results demonstrated that the conversion of fluorine-substituted phosphines to the corresponding phosphinate esters can be achieved more readily. In addition, the energy barrier for the reaction of a phosphine with dioxygen yielding the phosphine oxide was calculated to be much lower than that on the way to the phosphinate ester.

Density functional studies of dicobalt octacarbonyl-mediated azobenzene formation from 4-ethynylaniline.

Two adiabatic potential-energy surfaces are employed for probing the processes of [Co2(CO)8]-mediated C6H5N=NC6H5 formation from NH2C6H5. Elementary steps, including oxidative addition of the coordinated amine proton to the cobalt center, reductive elimination of H2, CO association, and the coupling process of the diamino fragments, are modeled and examined by using DFT methods at the B3 LYP/631 LAN level. The formation of C6H5N=NC6H5 from NH2C6H5 through reductive coupling is a thermodynamically unfavorable process. Three hydride-migration processes, from the proton of N-H to the cobalt center, are established as the most energy-demanding steps. The activation energies (deltaG*) are calculated as 49.4, 55.4, and 33.3 kcal mol(-1), respectively, for the proposed reaction route 1. These large activation energies might be reduced slightly by purposely adding small protic molecules, such as H2O, or by changing the active metal from Co to a heavier metal, such as Rh or Ir. An alternative pathway, route 2, is also proposed, in which transition states with four-membered rings are formed. By this route, severe strain caused by the formation of three-membered rings during the hydride-migration processes in route 1 can be avoided. Route 2 is established as the more energy-feasible reaction pathway.

Preparation and NMR studies of cobalt-containing diphosphine ligand chelated W, Ru, Au and Pd complexes: Suzuki cross-coupling reactions and carbonylation catalyzed by the Pd complex.

Treatment of a cobalt-containing diphosphine ligand, [[mu-P,P-PPh2CH2PPh2]Co2(CO)4[mu-PPh2C[triple bond]CPPh2]] 1 with metal complexes W(CO)6, Ru3(CO)12, AuCl(tht)(tht = tetrahydrothiophene) and (COD)PdCl2(COD = 1,5-cycloctadiene) gave 1-chelated metal complexes [(1)W(CO)4], [(mu-1)Ru3(CO)10] 4, [(1)(AuCl)2] 5 and [(1)PdCl2] 6, respectively. All these compounds were characterized by spectroscopic means whereas 3, 4 and 6 were also studied by X-ray diffraction. These compounds display chelating and bridging modes of metal-phosphine complexation. Variable-temperature 1H and 31P NMR experiments were carried out for 3-6 and revealed that the fluxional behavior of each individual bridging dppm fragment was affected greatly by the bite angle of 1 in each metal complex. Suzuki cross-coupling reactions were satisfactorily catalyzed by under mild conditions. The reactions of aryl halides or iodothiophenes with chloroform and alkali in biphasic solution utilizing a catalytic amount of result into the formation of benzoic and thiophenic acids, respectively.