Recently, microRNA-665 (miR-665) has been reported to function as both tumour suppressor and oncogene in several cancer types, including gastric cancer, hepatocellular cancer, and lung cancer. However, the biological function of miR-665 and its precise mechanisms in gastric cancer (GC) have not been well clarified. The aim of this study was to study the roles of miR-665/PPP2R2A axis in GC. The levels of PPP2R2A and miR-665 were detected by quantitative PCR assay in GC tissues and cell lines. Moreover, the biological roles of miR-665 and PPP2R2A in GC cells were assessed by cell proliferation, invasion, and epithelial-mesenchymal transition (EMT).The mRNA and protein levels of PPP2R2A were determined by using quantitative PCR and Western blotting assays. Luciferase assays were used to confirm that PPP2R2A was one target of miR-665. In this study, the miR-665 level was dramatically reduced in GC tissues and cell lines, and the PPP2R2A expression was significantly enhanced. What is more, the PPP2R2A expression was negatively related to the miR-665 level in GC tissues. Furthermore, up-regulation of miR-665 obviously restrained GC cells proliferation, invasion, and EMT. We confirmed that miR-665 could directly target PPP2R2A by luciferase reporter assay. Besides, knockdown of PPP2R2A also could markedly inhibit the proliferation, invasion and EMT of GC cells.Finally, overexpression of miR-665 in GC cells partially reversed the promoted effects of PPP2R2A up-regulation. Overexpression of miR-665 restrained GC cells proliferation, invasion and EMT via regulation of PPP2R2A.Significance of the study miR-665 has been reported to function as oncogene or tumour suppressor in different cancers. However, the precise roles of miR-665 in GC have not been elucidated. Our study for the first time demonstrated that miR-665 level was significantly down-regulated in GC. Additionally, miR-665 overexpression inhibited cell growth, invasion, and EMT of GC. Moreover, our data suggested a significant negative correlation between miR-665 and PPP2R2A expression in GC. MiR-665 suppressed GC cell proliferation, invasion, and EMT by directly targeting PPP2R2A, which suggested important roles for miR-665/PPP2R2A axis in the GC pathogenesis and its potential application in cancer therapy.

The present study adopted a repetition priming paradigm to investigate the bidialectal (bilingual) representation of speakers with different native dialects by event-related potential (ERP) technique. Proficient Mandarin-Cantonese and Cantonese-Mandarin bidialectals participated in the study. They were required to judge whether a word was a biological word or not, when the words (target word) were represented under four types of repetition priming conditions: Mandarin (prime)-Mandarin (target), Mandarin (prime)-Cantonese (target), Cantonese (prime)-Cantonese (target) and Cantonese (prime)-Mandarin (target). Results of reaction time and accuracy primarily indicated larger repetition priming effects in Mandarin-Mandarin and Cantonese-Cantonese (within-language) conditions than that in Mandarin-Cantonese and Cantonese-Mandarin (between-language) conditions. But more importantly, P200 and N400 mean amplitudes revealed distinct repetition priming effects between two types of participants. Specifically, both P200 and N400 indicated that the repetition priming effect in Mandarin-Mandarin condition was larger than that in Cantonese-Cantonese condition for Mandarin-Cantonese participants, whereas it was opposite for Cantonese-Mandarin participants. In addition, P200 also suggested opposite patterns of repetition priming effects in between-language priming conditions for two groups of participants. The repetition priming effect in Mandarin-Cantonese condition was larger than that in Cantonese-Mandarin condition for Mandarin-Cantonese participants, while for Cantonese-Mandarin participants, it was opposite (Mandarin-Cantonese < Cantonese-Mandarin). The results implied a clear asymmetric representation of two dialects for proficient bidialectals. They were further discussed in light of native dialect and language use frequency.

Language switching is an important issue in the study of bilinguals. However, how the nontarget language affects the production of the target language under the language switch condition is still unclear, especially for bilinguals who speak two dialects (bidialectals). In the present study, we investigate this issue by a picture-naming task and using an event-related potential (ERP) technique. Two groups of proficient bidialectals, Mandarin (L1)-Cantonese (L2) and Cantonese (L1)-Mandarin (L2), participated in the study. They were required to name pictures with Mandarin or Cantonese under language switching conditions and language nonswitching conditions. The results showed that participants of both groups showed significant longer reaction time, larger P200, and smaller N400 under language switching conditions than that under language nonswitching conditions, which reflects the language switching costs. Moreover, participants of the two groups showed different P200 and N400 between Mandarin-Cantonese (MC) switching conditions and Cantonese-Mandarin (CM) switching conditions. Specifically, MC bidialectals showed larger P200 under the CM condition than that under the MC condition, whereas CM bidialectals showed an opposite P200 pattern (CM conditionCM condition). These findings supported the language-unspecific selection theory. Overall, our study is the first to provide electrophysiological evidence of language switching between two dialects.