Anticancer mechanism studies of iridium(III) complexes inhibiting osteosarcoma HOS cells proliferation.

Three iridium (III) polypyridine complexes [Ir(bzq)2(maip)](PF6) (Ir1，bzq = benzo[h]quinoline, maip = 3-aminophenyl-1H-imidazo[4,5-f][1,10]phenanthroline), [Ir(bzq)2(apip)](PF6) (Ir2, apip = 2-aminophenyl-1H-imidazo[4,5-f][1,10]phenanthroline) and [Ir(bzq)2(paip)](PF6) (Ir3, paip = 4-aminophenyl-1H-imidazo[4,5-f][1,10]phenanthroline) were synthesized and characterized. The cytotoxic activities of the three complexes against human osteosarcoma HOS, U2OS, MG63 and normal LO2 cells were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method. The results showed that Ir1-3 exhibited moderate antitumor activity against HOS with IC50 of 21.8 ± 0. 4 µM,10.5 ± 1.8 µM and 7.4 ± 0.4 µM, respectively. We found that Ir1-3 can effectively inhibit HOS cells growth and blocked the cell cycle at the G0/G1 phase. Further studies revealed that complexes can increase intracellular reactive oxygen species (ROS) and Ca2+, which accompanied by mitochondria-mediated intrinsic apoptosis pathway. In addition, autophagy was also investigated. Taken together, the complexes induce HOS apoptosis through a ROS-mediated mitochondrial dysfunction pathway and inhibition of the PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B)/mTOR (mammalian target of rapamycin) signaling pathway. This study provides useful help for understanding the anticancer mechanism of iridium (III) complexes toward osteosarcoma treatment.

Antitumor activity studies of iridium (III) polypyridine complexes-loaded liposomes against gastric tumor cell in vitro.

Two iridium (III) polypyridine complexes [Ir(ppy)2(BIP)]PF6 (ppy = 2-phenylpyridine, BIP = 2-biphenyl-1H-imidazo[4,5-f][1,10]phenanthroline, Ir1), [Ir(piq)2(BIP)]PF6 (piq = 1-phenylisoquinoline, Ir2) and their liposomes Ir1lipo and Ir2lipo were synthesized and characterized. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cytotoxic activity against several cancer cells (A549, HepG2, SGC-7901, Bel-7402, HeLa) and non-cancer cell (mouse embryonic fibroblast, NIH3T3). The results showed that Ir1lipo displays the high cytotoxicity toward SGC-7901 with IC50 value of 5.8 ± 0.2 µM, while the complexes have no cytotoxicity toward A549, HepG2, Bel-7402 and HeLa cells. The cell colony demonstrated that the iridium (III) complexes-loaded liposomes can inhibit cell proliferation, induce cell cycle arrest at G0/G1 phase. Moreover, they also cause autophagy, induce a decrease of mitochondrial membrane potential and increase intracellular reactive oxygen species (ROS) content. These results suggest that the complexes encapsulated liposomes Ir1lipo and Ir2lipo inhibit the growth of SGC-7901 cells through a ROS-mediated mitochondrial dysfunction and activating the PI3K (phosphoinositide-3 kinase)/ AKT (protein kinase B) signaling pathways.

Osteogenesis activity of isocoumarin a through the activation of the PI3K-Akt/Erk cascade-activated BMP/RUNX2 signaling pathway.

Bone formation refers to a series of complex events related to the activities of osteoblasts. In this study, we evaluated the osteogenesis activity of a natural compound named isocoumarin A that was isolated from the rhizomes of Polygonum amplexicaule on the non-transformed preosteoblastic cell line MC3T3-E1 for an in vitro study, and the results revealed that it increased the proliferation and promoted the mineralization of the extracellular matrix of MC3T3-E1 cells after treatment for 3 d in a dose-dependent manner. The cell metabolic activity peaked at 169% at 10 µM, and the activity of alkaline phosphatase (ALP) tripled to 15.94 U/mg compared with the control group. The protein levels of morphogenetic protein 2 (BMP-2), runt-related transcription factor 2 (RUNX2), ALP, and the mRNA levels of ALP, type I collagen (COL-1), and osteocalcin (OCN) were also upregulated after isocoumarin A administration. The mechanism investigation revealed that these effects were associated with the activation of the p-Akt/p-Erk1/2-activated BMP/RUNX2 signaling pathway. Subsequently, the in vivo investigation on the zebrafish embryos model demonstrated that isocoumarin A (0.30 mM) increased the number of vertebrae (5.38 ±â€¯2.07 pcs) and the vertebral area (433.25 ±â€¯111.77 µm2) in the development process of zebrafish embryos after a 7-day postfertilization (dpf) culture compared with the control group (2.50 ±â€¯1.16 pcs and 209.75 ±â€¯86.40 µm2). Together, these results indicated that isocoumarin A could be viewed as a promising candidate in early drug discovery and development to promote the healing of fractures and postmenopausal osteoporosis.

[Genetic diversity and phylogeny of rhizobia isolated from peanut (Arachis hypogaea)].

Forty three rhizobium strains isolated from peanut (Arachis hypogaea) and 15 reference strains from other genus and species were analyzed by the method of 16S rRNA RFLP, 16S rRNA sequencing and 16S-23S IGS PCR RFLP. The results of the 16S rRNA RFLP shown that 43 strains tested were all ascribed to the genus of Bradyrhizobium phylogenetically. Strains tested were adjacent to the B. japonicum and far from B. elkanii 16S rRNA genotype. The genotypes generated by the 4 restriction endonucleases, Mbo I, Dde I, Hae III and Msp I, were same as the representatives of B. japonicum. The dendrogram generated by 16S rRNA sequence and Neighbor-joining method shown that peanut rhizobia clustered into the subcluster represented by B. japonicum and B. liaoningense, were more close to B. liaoningense genetically, and the sequence difference between them was less than 1%. High sequence similarity was also determined between B. liaoningense and B. japonicum. JZ1, representative strain of peanut rhizobia were systematically far from the B. elkanii, and the sequence divergence about 2%. The results from IGS RFLP analysis indicated that although they were phylogenetically close to B. japonicum and B. elkanii, peanut rhizobia forming an independent group at the similarity of 71% could be further divided into four subgroups, A, B, C and D. Subgroup A consisted of strains from different region, subgroup B was composed of strains from Wuchang, Qianjiang and Jingzhou, subgroup C was mainly composed of strains from Jingzhou and starins of subgroup D mainly from Neijiang. Reference strains from B. japonicum and B. elkanii were independently clustered into the subgroup E at the similarity of 71%. The geographical factor effect on genetic diversity of rhizobia was found.