Chemotherapy has been reported to induce epithelialmesenchymal transition (EMT) in tumor cells, which is a critical step in the process of metastasis leading to cancer spreading and treatment failure. However, the underlying mechanisms of chemotherapy-induced EMT remain unclear, and the involvement of microRNAs (miRNA) in this process is poorly understood. To address these questions, we established stable chemotherapy-resistant tongue squamous cell carcinoma (TSCC) cell lines CAL27-res and SCC25-res by exposing the parental CAL27 and SCC25 lines to escalating concentrations of cisplatin for 6 months. CAL27-res and SCC25-res cells displayed mesenchymal features with enhanced invasiveness and motility. MiRNA microarray illustrated that miR-200b and miR-15b were the most significantly downregulated microRNAs in CAL27-res cells. Ectopic expression of miR-200b and miR-15b with miRNA mimics effectively reversed the phenotype of EMT in CAL27-res and SCC25-res cells, and sensitized them to chemotherapy, but inhibition of miR-200b and miR-15b in the sensitive lines with anti-sense oligonucleotides induced EMT and conferred chemoresistance. Retrieving the expression of B lymphoma Mo-MLV insertion region 1 homolog (BMI1), a target for miR-200b and miR-15b, in the presence of the miRNA mimics by transfecting CAL27-res cells with pcDNA3.1-BMI1-carrying mutated seed sequences of miR-200b or miR-15b at its 3 0 -UTR recapitulated chemotherapy-induced EMT. In vivo, enforced miR-200b or miR-15b expression suppressed metastasis of TSCC xenografts established by CAL27-res cells. Clinically, reduced miR-200b or miR-15b expression was associated with chemotherapeutic resistance in TSCCs and poor patient survival. Our data suggest that reduced expression of miR-200b and miR-15b underscores the mechanisms of chemotherapy-induced EMT in TSCC, and may serve as therapeutic targets to reverse chemotherapy resistance in tongue cancers.

Polymorphism of HLA‐DRB1, DQB1 and DPB1 was revealed with a sequencing‐based typing (SBT) method in unrelated healthy volunteers from the Naxi ethnic group. Among the 43 DRB1 alleles detected, the most common allele was DRB1*12021 with a frequency of 17%, followed by DRB1*08032, DRB1*09012 and DRB1*1404 with frequencies of 8.5%, 7.4% and 7.4%, respectively. Among 23 DQB1 alleles detected, the most frequent DQB1 allele was DQB1*03011/0309 (21.9%), followed by DQB1*0502 (16.4%) and DQB1*05031 (9.6%). For the DPB1 locus, the most common alleles were DPB1*0501 (25.5%), DPB1*0402 (14.6%) and DPB1*02012 (12.0%). The most common DRB1‐DQB1‐DPB1 haplotype was DRB1*1404‐DQB1*05031‐DPB1*0402 with a frequency of 5.26%, followed by the DRB1*08032‐DQB1*06011‐DPB1*1301 (3.51%). The distribution characteristics of the HLA class II alleles revealed that the Naxi ethnic group belonged to the Southern group of Chinese.

This study combined the micro-cross-section cultural system with in vitro mutagenesis induced by ethyl methanesulphonate (EMS) to screen for fusarium wilt-resistant lines of Brazil banana (Musa spp., AAA). The results indicated that the optimum EMS concentration and duration for the treatment of micro-cross-sections cut from the pseudostem of tissue-cultured plantlet were 300 mM and 60 min, respectively. Under the optimal treatment, an average of 2AE2 regenerated shoots were produced from each explant. One hundred regenerated plantlets were used for screening for fusarium wilt-resistant lines by the early screening technique. The initial disease symptom -yellowing in lower leaves of susceptible plantlets -was observed 2 weeks after inoculation. After 2 months, only six plants survived -the putative fusarium wilt-resistant lines. The fusarium wilt pathogen Fusarium oxysporum f. sp. cubense race 4, was identified in the preliminary test field by a SCAR marker technique. Of the six putative resistant lines, five survived the preliminary field test. The regenerated plantlets from these five fusarium wilt-resistant lines were subjected to early screening again, where they showed markedly reduced disease incidences compared with regenerated plantlets of Brazil banana (control). It was concluded that EMS-induced mutation of banana through the micro-cross-section cultural system is potentially useful for banana improvement.

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