Labeled microRNA pull-down assay system: an experimental approach for high-throughput identification of microRNA-target mRNAs

We developed a simple, direct and cost-effective approach to search for the most likely target genes of a known microRNA (miRNA) in vitro. We term this method ‘labeled miRNA pull-down (LAMP)’ assay system. Briefly, the pre-miRNA is labeled with digoxigenin (DIG), mixed with cell extracts and immunoprecipitated by anti-DIG antiserum. When the DIG-labeled miRNA and bound mRNA complex are obtained, the total cDNAs are then subcloned and sequenced, or RT–PCR-amplified, to search for the putative target genes of a known miRNA. After successfully identifying the known target genes of Caenorhabditis elegans miRNAs lin-4 and let-7 and zebrafish let-7, we applied LAMP to find the unknown target gene of zebrafish miR-1, which resulted in the identification of hand2. We then confirmed hand2 as a novel target gene of miR-1 by whole-mount in situ hybridization and luciferase reporter gene assay. We further validated this target gene by microarray analysis, and the results showed that hand2 is the top-scoring among 302 predicted putative target genes. We concluded that LAMP is an experimental approach for high-throughput identification of the target gene of known miRNAs from both C. elegans and zebrafish, yielding fewer false positive results than those produced by using only the bioinformatics approach.     

Distinct population of highly malignant cells in a head and neck squamous cell carcinoma cell line established by xenograft model

The progression and metastasis of solid tumors, including head and neck squamous cell carcinoma (HNSCC), have been related to the behavior of a small subpopulation of cancer stem cells. Here, we have established a highly malignant HNSCC cell line, SASVO3, from primary tumors using three sequential rounds of xenotransplantation. SASVO3 possesses enhanced tumorigenic ability both in vitro and in vivo. Moreover, SASVO3 exhibits properties of cancer stem cells, including that increased the abilities of sphere-forming, the number of side population cells, the potential of transplanted tumor growth and elevated expression of the stem cell marker Bmi1. Injection of SASVO3 into the tail vein of nude mice resulted in lung metastases. These results are consistent with the postulate that the malignant and/or metastasis potential of HNSCC cells may reside in a stem-like subpopulation.     

Synthesis and antitumor activity of novel enediyne-linked pyrrolo[2,1-c][1,4]benzodiazepine hybrids

A series of novel pyrrolo[2,1-c][1,4]benzodiazepine (PBD) hybrids linked with enediyne is described. These compounds were prepared by linking C-8 of DC-81 (1) with an enediyne (10–16) through carbon chain linkers to afford PBD hybrid agents 17–23 in good yields. Most of the hybrids on human cancer cell lines exhibited higher cytotoxicity, and an increase in the sub-G1 population than 1. In a previous article, we have demonstrated that DC-81-indole conjugate agents (3–6) are potent inducers of cell apoptosis in melanoma. In the present article, we investigated whether DC-81-enediyne agents possess more cytotoxicity than 6 on human 293T cells. Our data revealed that treatment of 293T cells with DC-81-enediyne resulted in a significant increase of annexin V binding, caspase-3 degradation, and p53 arrest to identify apoptotic cells than 6. These results suggest that the DC-81-enediyne agents are more efficient in inducing apoptosis than DC-81-indole in 293T cells.     

4-Fluoro-N-butylphenylacetamide (H6) inhibits cell growth via cell-cycle arrest and apoptosis in human cervical cancer cells

Phenylacetate induced tumor cytostasis and differentiation. The chemotherapeutic function of the compound in lung cancer has been previously reported, however, whether or not phenylacetate performs other activities is not known. In this study, the potential usage of synthetic phenylacetate derivatives, 4-fluoro-N-butylphenylacetamides (H6) was investigated in human cervical cancer cells. H6 displayed anti-proliferative and apoptosis effects, with an IC₅₀ of 1.0–1.5 mM and an ID₅₀ of about 3 days. Moreover, it significantly induced apoptosis as evidenced by morphological changes, DAPI and TUNEL staining and DNA fragmentation. H6 increased the expression of Bax protein, whereas it decreased the expression of Bcl-2 protein. H6 also induced accumulation of cytosolic cytochrome c and activation of caspase cascade (caspase-9 and -3), and then DNA fragmentation and apoptosis occurred. The underlying anti-proliferative mechanism for H6 is likely due to the down-regulation of G2/M-phase association cdks and cyclins and up-regulation of p53 to mediate G2/M-phase arrest. Furthermore, the decrease of Bcl-2 and activation of Bax, caspase-9/caspase-3 may be the effectors of H6-induced apoptosis.     

Antagonistic activity of Lactobacillus acidophilus RY2 isolated from healthy infancy feces on the growth and adhesion characteristics of enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAggEC) infection is an important cause of acute diarrhea, affecting children in developing countries and travelers visiting tropical or subtropical areas. Three probiotics can exert bacteriostatic or bactericidal effects on human and animal intestinal pathogens, the efficiency of probiotics on EAggEC infection remains unclear. In this study, the antagonistic activity of probiotic bacteria isolated from infant faeces was examined against several EAggEC stains. While three isolates, Lactobacillus acidophilus RY2, Lactobacillus salivarius MM1 and Lactobacillus paracasei En4 were shown to significantly inhibit the growth of EAggEC. In addition, the antagonistic activity of the Lactobacillus species was maintained despite heating (100 °C, 15 min) of cell free culture supernatant (CFCS). The antagonistic activity of the CFCS however, could be reduced following lactate dehydrogenase treatment and at pH 7.2. Furthermore, in an adhesion–inhibition assay, L. acidophilus RY2 was shown to be more effective than L. salivarius MM1 and L. paracasei EN4. This study suggests that L. acidophilus RY2 could be used as a probiotic organism against EAggEC.     

Characterizing the polymeric status of Helicobacter pylori heat shock protein 60

Helicobacter pylori heat shock protein 60 (HpHsp60) was first identified as an adhesion molecule associated with H. pylori infection. Here we have analyzed the structure of HpHsp60 via amino acid BLAST, circular dichroism, and electrophoresis and the results indicate that most recombinant HpHsp60 molecules exist as dimers or tetramers, which is quite different from Escherichia coli Hsp60. Treatment of human monocytic cells THP-1 with HpHsp60 was found to up-regulate a panel of cytokines including IL-1α, IL-8, IL-10, IFN-γ, TNF-α, TGF-β, GRO, and RANTES. Carboxymethylated HpHsp60 molecules with a switched oligomeric status were able to further enhance NF-κB-mediated IL-8 and TNF-α secretion in THP-1 cells compared to unmodified HpHsp60 molecules. These results indicated that the oligomeric status of HpHsp60s might have an important role in regulating host inflammation and thus help facilitate H. pylori persistent infection.     

Human papillomavirus in oral leukoplakia is no prognostic indicator of malignant transformation

Background: Oral leukoplakia is considered as a premalignant lesion for the development of oral squamous cell carcinoma (OSCC); several risks factors have been reported to contribute to this step-wise carcinogenesis; including human papillomavirus (HPV). Nevertheless, few reports have analyzed both the HPV status and the genotype in a single individual who develops OSCC from pre-existing oral leukoplakia. In this study, we surveyed the HPV status, genotype and clinicopathological risk factors in cases of malignant transformation from pre-existing oral leukoplakia. Methods: HPV genomic DNA was detected by PCR (MY09/MY11 in conjugation with nested primer-GP05+/GP06+) from paraffin sections, and the genotype was determined by direct DNA sequencing. Fisher's exact test and logistic regression were used to analyze risk factors for malignant transformation of oral cavity leukoplakia. Results: One hundred and sixty-seven patients with oral leukoplakia were enrolled; including 12 who had malignant transformation from the pre-existing oral leukoplakia. HPV prevalence was 22.8% in cases with oral leukoplakia. The risk factor associated with malignant transformation was recurrence of leukoplakia after treatment (p = 0.03), nevertheless, HPV status was not statistically significant by logistic regression analysis. Among these 12 patients with malignant transformation from pre-existing oral leukoplakia, the status or genotype of HPV was chaotic; the oral habits of these patients might contribute to malignant transformation. Conclusions: Our data suggest that HPV in oral leukoplakia is no prognostic indicator of malignant transformation.     

Extension of the core map of common bean with EST-SSR,RGA, AFLP,and putative functional markers

Microsatellites and gene-derived markers are still underrepresented in the core molecular linkage map of common bean compared to other types of markers. In order to increase the density of the core map, a set of new markers were developed and mapped onto the RIL population derived from the ‘BAT93’ × ‘Jalo EEP558’ cross. The EST-SSR markers were first characterized using a set of 24 bean inbred lines. On average, the polymorphism information content was 0.40 and the mean number of alleles per locus was 2.7. In addition, AFLP and RGA markers based on the NBS-profiling method were developed and a subset of the mapped RGA was sequenced. With the integration of 282 new markers into the common bean core map, we were able to place markers with putative known function in some existing gaps including regions with QTL for resistance to anthracnose and rust. The distribution of the markers over 11 linkage groups is discussed and a newer version of the common bean core linkage map is proposed.