First identification of multidrug-resistant Acinetobacter bereziniae isolates harboring bla NDM-1 from hospitals in South China.

This study is a first report on the identification of multidrug-resistant (MDR) Acinetobacter bereziniae among non-baumannii acinetobacters that had previously escaped automated laboratory detection, and characterize their clinical courses of infection at two tertiary-care hospitals in Shenzhen city, China (2015-2017). Herein, definitive identification by PCR was performed with universal and species-specific primers targeting 16S rDNA and rpoB genes, respectively, followed by Sanger sequencing and blast analysis. Antimicrobial susceptibility of A. bereziniae isolates was assessed accordingly. Three of the five identified A. bereziniae isolates exhibited carbapenem-resistance and were subjected to a multiplex PCR assay to detect drug-resistance genes. Sequences of the rpoB amplicon were aligned with curated sequences from global databases for phylogenetic analysis on evolutionary relations. Five clinical isolates of A. bereziniae were thereby re-identified, whose infections were primarily nosocomial. Automated identification and susceptibility testing systems (Phoenix-100 and VITEK 2) proved insufficient for discriminating A. bereziniae from other acinetobacters such as Acinetobacter baumannii and Acinetobacter guillouiae. Among these isolates, three exhibited carbapenem-resistant phenotypes indistinguishable from that of carbapenem-resistant A. baumannii. The carbapenem-resistant A. bereziniae isolates were subsequently confirmed to carry a bla NDM-1 (New Delhi metallo-ß-lactamase-1) gene downstream of ISAba125. Phylogenetic analysis revealed that A. bereziniae isolates evolved slowly but independently in local habitats. A. bereziniae isolates are difficult to distinguish by traditional automated detection systems. PCR-based identification via amplification and sequencing of selected house-keeping genes provides sufficient resolution for discriminating the isolates.

Brefeldin A Induces Apoptosis, Inhibits BCR-ABL Activation, and Triggers BCRABL Degradation in Chronic Myeloid Leukemia K562 Cells.

BACKGROUND: Chronic Myeloid Leukemia (CML) is a myeloproliferative disease caused by BCR-ABL oncoprotein. Tyrosine kinase inhibitors have been developed to inhibit the activity of BCR-ABL; however, drug resistance and side effect occur in clinic application. Therefore, it is urgent to find novel drugs for CML treatment. Under the guidance of cytotoxic activity, crude extracts of 55 fungal strains from the medicinal mangrove Acanthus ilicifolius were evaluated, and one potent cytotoxic natural compound, brefeldin A (BFA), was discovered from Penicillium sp. (HS-N-29). OBJECTIVE: This study was aimed to determine the cytotoxic activity of BFA and the effect on the activation and expression of BCR-ABL in K562 cells. METHODS: We evaluated cytotoxic activity by MTT assay and soft agar clone assay; apoptosis and cell cycle distribution by Muse cell analyzer. The protein level of BCR-ABL and signaling molecules was detected by western blotting, and the mRNA level of BCR-ABL was determined by RT-PCR. RESULTS: BFA inhibited cell proliferation, induced G2/M cell cycle arrest, and stimulated cell apoptosis in K562 cells. Importantly, for the first time, we revealed that BFA inhibited the activation of BCR-ABL and consequently inhibited the activation of its downstream signaling molecules in K562 cells. Moreover, we found BFA degraded BCR-ABL without affecting its transcription in K562 cells, and BFA-induced BCR-ABL degradation was related to caspase activation, while not to autophagy or ubiquitinated proteasome degradation pathway. CONCLUSION: Our present results indicate that BFA acts as a dual functional inhibitor and degrader of BCR-ABL, and BFA is a potential compound for chemotherapeutics to overcome CML.

Structural insights into the inhibition of bacterial RecA by naphthalene polysulfonated compounds.

As a promising target for alternative antimicrobials, bacterial recombinase A (RecA) protein has attracted much attention for its roles in antibiotic-driven SOS response and mutagenesis. Naphthalene polysulfonated compounds (NPS) such as suramin have previously been explored as antibiotic adjuvants targeting RecA, although the underlying structural bases for RecA-ligand interactions remain obscure. Based on our in silico predictions and documented activity of NPS in vitro, we conclude that the analyzed NPS likely interact with Tyr103 (Y103) and other key residues in the ATPase activity center (pocket A). For validation, we generated recombinant RecA proteins (wild-type versus Y103 mutant) to determine the binding affinities for RecA protein interactions with suramin and underexamined NPS in isothermal titration calorimetry. The corresponding dissociation constants (K d) ranged from 11.5 to 18.8 µM, and Y103 was experimentally shown to be critical to RecA-NPS interactions.

miR-421 promotes the viability of A549 lung cancer cells by targeting forkhead box O1.

MicroRNA (miR)-421 has been reported to serve various important roles in numerous types of cancer, including neuroblastoma and gastric cancer. However, to the best of our knowledge, few reports have determined the role of miR-421 in lung cancer. The aim of the current study was to analyze the expression levels of miR-421 in A549 lung cancer cells, to determine the target gene of miR-421, and to investigate the function and mechanism of miR-421 in cellular cytotoxicity. miR-421 expression levels were analyzed in A549 lung cancer cells using reverse transcription-quantitative PCR, a MTT assay was performed to determine the effect of miR-421 on A549 cell cytotoxicity and the protein expression levels of forkhead box O1 (FOXO1) were determined via western blotting. The target gene of miR-421 was predicted and verified using TargetScan and a dual-luciferase reporter assay, respectively. The results revealed that miR-421 expression levels were significantly upregulated in A549 lung cancer cell lines compared with the normal cells (P<0.01). Additionally, it was discovered that miR-421 promoted A549 cell viability (P<0.01) compared with A549 transfected with negative control. miR-421 was also identified to bind to the 3'-untranslated region of FOXO1. In A549 cells transfected with miR-421-mimics, the expression levels of phosphorylated (p)-AKT, p-glycogen synthase kinase-3ß, p-retinoblastoma and cyclin D1 were significantly upregulated (P<0.01), whereas the expression levels of FOXO1 and p21 were significantly downregulated (P<0.01) compared with the control group. In conclusion, the results of the present study suggested that miR-421 may promote the viability of A549 lung cancer cells by targeting FOXO1 and modulating cell cycle, indicating that targeting miR-421 and FOXO1 may represent future therapeutic strategies for the treatment of patients with lung cancer.

Computational elucidation of the binding mechanisms of curcumin analogues as bacterial RecA inhibitors.

Antimicrobial resistance (AMR) presents as a serious threat to global public health, which urgently demands action to develop alternative antimicrobial strategies with minimized selective pressure. The bacterial SOS response regulator RecA has emerged as a promising target in the exploration of new classes of antibiotic adjuvants, as RecA has been implicated in bacterial mutagenesis and thus AMR development through its critical roles in error-prone DNA repair. The natural product curcumin has been reported to be an effective RecA inhibitor in several Gram-negative bacteria, but details on the underlying mechanisms are wanting. In order to bridge the gap in how curcumin operates as a RecA inhibitor, we used computational approaches to model interactions between RecA protein and curcumin analogues. We first identified potential binding sites on E. coli RecA protein and classified them into four major binding pockets based on biological literature and computational findings from multiple in silico calculations. In docking analysis, curcumin-thalidomide hybrids were predicted to be superior binders of RecA compared with bis-(arylmethylidene)acetone curcumin analogues, which was further confirmed by MMGBSA calculations. Overall, this work provides mechanistic insights into bacterial RecA protein as a target for curcumin-like compounds and offers a theoretical basis for rational design and development of future antibiotic adjuvants.

GPER/ERK&AKT/NF-κB pathway is involved in cadmium-induced proliferation, invasion and migration of GPER-positive thyroid cancer cells.

The higher incidence of thyroid cancer in women during reproductive years compared with men and the increased risk associated with the therapeutic use of estrogen have strongly suggested that estrogen may be involved in the occurrence and development of thyroid cancer. Cadmium (Cd) is a potent metalloestrogen that disrupts the endocrine system by mimicking the effects of 17ß-estradiol (E2). In the present study, we demonstrate that similar to E2 and G1, a specific agonist for G protein-coupled estrogen receptor (GPER), Cd induces the proliferation, invasion and migration of human WRO and FRO thyroid cancer cells that have endogenous GPER. Moreover, like E2 and G1, Cd leads to a rapid activation of ERK/AKT, and then nuclear translocation of NF-κB, increased expression of cyclin A and D1, and secretion of IL-8, all of which are significantly attenuated by GPER blockage or knock-down in both WRO and FRO cells. Furthermore, the Cd-induced proliferation, invasion and migration are suppressed either by specific inhibitors for GPER, ERK, AKT and NF-κB, or by knock-down of GPER. These results suggest that GPER/ERK&AKT/NF-κB signaling pathway is involved in the Cd-induced proliferation, invasion and migration of GPER-positive thyroid cancer cells.

Up-regulation of Hsp27 by ERα/Sp1 facilitates proliferation and confers resistance to apoptosis in human papillary thyroid cancer cells.

17ß-estradiol (E2) has been suggested to play a role in the development and progression of papillary thyroid cancer. Heat shock protein 27 (Hsp27) is a member of the Hsp family that is responsible for cell survival under stressful conditions. Previous studies have shown that the 5'-promoter region of Hsp27 gene contains a specificity protein-1 (Spl) and estrogen response element half-site (ERE-half), which contributes to Hsp27 induction by E2 in breast cancer cells. However, it is unclear whether Hsp27 can be up-regulated by E2 and which estrogen receptor (ER) isoform and tethered transcription factor are involved in this regulation in papillary thyroid cancer cells. In the present study, we demonstrated that Hsp27 can be effectively up-regulated by E2 at mRNA and protein levels in human K1 and BCPAP papillary thyroid cancer cells which have more than two times higher level of ERα than that of ERß. The up-regulation of Hsp27 by E2 is mediated by ERα/Sp1 and ERß has repressive effect on this ERα/Sp1-mediated up-regulation of Hsp27. Moreover, we showed that the up-regulation of Hsp27 by ERα/Sp1 facilitates proliferation and confers resistance to apoptosis through interaction with procaspase-3. Targeting this pathway may be a potential strategy for therapy of papillary thyroid cancer.

Concomitant high expression of BRAFV600E, P-cadherin and cadherin 6 is associated with High TNM stage and lymph node metastasis in conventional papillary thyroid carcinoma.

CONTEXT AND OBJECTIVE: BRAFV600E mutation is the most common activating mutation associated with aggressive behaviours in human tumours including conventional papillary thyroid carcinoma (cPTC). P-cadherin and cadherin 6 have been shown to be mesenchymal-associated cadherins and promote cancer cell invasion and metastasis. The purpose of this study was to examine BRAFV600E, P-cadherin and cadherin 6 expressions in cPTC and to assess the association of their expression with clinicopathological indicators. METHODS: BRAFV600E, P-cadherin and cadherin 6 protein expressions in 80 cPTCs, 61 nodular hyperplasia and 76 normal thyroid tissues were examined by immunohistochemistry. The correlation of their protein expression with clinicopathological indicators of cPTC was statistically analysed. RESULTS: Protein expression of BRAFV600E, P-cadherin and cadherin 6 was upregulated in cPTC. High protein expression of BRAFV600E, P-cadherin and cadherin 6 was significantly correlated with high TNM stage and lymph node metastasis (LNM) (P < 0·001). Furthermore, BRAFV600E, P-cadherin and cadherin 6 protein expressions were correlated with one another. BRAFV600E high expression combined with both P-cadherin and cadherin-6 high expressions had stronger correlation with high TNM stage and LNM when compared with BRAFV600E high expression combined with either P-cadherin or cadherin-6 high expression (P = 0·042, 0·017 for TNM stage and P = 0·003, 0·006 for LNM, respectively) and only BRAFV600E high expression (P < 0·001 for both TNM stage and LNM). CONCLUSIONS: Concomitant high expression of BRAFV600E, P-cadherin and cadherin 6 is strongly associated with high TNM stage and LNM in cPTC.

Downregulation of GSK3ß by miR-544a to maintain self-renewal ability of lung caner stem cells.

In order to study the influence and mechanism of miR-544a on the self-renewal ability of lung cancer stem cells, TargetScan was used to predict the target gene of miR-544a. A luciferase reporter system and western blotting were used to validate the target genes identified by TargetScan. 95C and 95D low and high metastatic human lung cancer cells were transfected with miR-544a, and quantitative polymerase chain reaction (qPCR) was used to verify the miR-544a expression in these two cell lines. Tumor ball (spheroid) suspension culture was use to study the effects of miR-544a on lung cancer stem cells. TargetScan predicted that miR-544a interacted with GSK3ß. A luciferase reporter system (F=201.37, P<0.01) and western blot analysis was used to validate that miR-544a could inhibit the expression of GSK3ß, while ß-catenin and CD133 were significantly increased in miR-544a-overexpressing 95C and 95D cells (F=9.43, 7.73 and 3.37, respectively; P<0.01). qPCR revealed that miR-544a was overexpressed in transfected 95C and 95D cells (20.51±0.97 and 15.16±1.38, respectively; F=418.05; P<0.01). miR-544a-overexpressing cells formed spheroids in suspension cultures of spheroid single cells. miR-544a was shown to reduce the expression of GSK3ß and activate the Wnt signaling pathway to maintain the self-renewal ability of lung caner stem cells.

DNA-Binding and Topoisomerase-I-Suppressing Activities of Novel Vanadium Compound Van-7.

Vanadium compounds were studied during recent years to be considered as a representative of a new class of nonplatinum metal anticancer agents in combination to its low toxicity. Here, we found a vanadium compound Van-7 as an inhibitor of Topo I other than Topo II using topoisomerase-mediated supercoiled DNA relaxation assay. Agarose gel electrophoresis and comet assay showed that Van-7 treatment did not produce cleavable complexes like HCPT, thereby suggesting that Topo I inhibition occurred upstream of the relegation step. Further studies revealed that Van-7 inhibited Topo I DNA binding involved in its intercalating DNA. Van-7 did not affect the catalytic activity of DNase I even up to100 µM. Van-7 significantly suppressed the growth of cancer cell lines with IC(50) at nanomolar concentrations and arrested cell cycle of A549 cells at G2/M phase. All these results indicate that Van-7 is a potential selective Topo I inhibitor with anticancer activities as a kind of Topo I suppressor, not Topo I poison.