Background:Recent studies have reported miR-145 dysregulated in colorectal cancer (CRC). In this study, miR-145 profiles were compared between CRC and corresponding non-tumour tissues.Methods:The expression levels of miR-145 were analysed in CRC cell lines and tumour tissues by real-time PCR. A luciferase reporter assay confirmed direct targets. The functional effects of miR-145 were examined in transfected CRC cells in vitro and in vivo using established assays.Results:Downregulation of miR-145 was detected in most primary CRC tumours, and was significantly correlated with a more aggressive phenotype of CRC in patients. In CRC cell lines, ectopic overexpression of miR-145 inhibited cell proliferation, motility and invasion in vitro. Stable overexpression of miR-145 suppressed tumour growth and pulmonary metastasis in vivo. Further studies indicated that miR-145 may directly interact with the 3′-untranslated region (3′-UTR) of Fascin-1 messenger RNA (mRNA), downregulating its mRNA and protein expression levels. In clinical specimens, Fascin-1 expression was negatively correlated with miR-145 expression.Conclusions:MiR-145 has a critical role in the inhibition of invasive and metastatic capacities of CRC, probably through directly targeting Fascin-1. This miRNA may be involved in the development and progression of CRC.

The expression levels of miR-365 vary in different malignancies. Herein, we found that miR-365 was overexpressed in both cells and clinical specimens of cutaneous squamous cell carcinoma (SCC). We demonstrated that the HaCaTpre-miR-365-2 cell line, which overexpressed miR-365, could induce subcutaneous tumors in vivo. Antagomir-365, an anti-miR-365 oligonucleotide, inhibited cutaneous tumor formation in vivo, along with G1 phase arrest and apoptosis of cancer cells. These findings suggest that miR-365 may act as an onco-miR in cutaneous SCC both in vitro and in vivo. The present study provides valuable insight into the role of miR-365 in cutaneous SCC formation, which can help develop new drug and miR-365 target-based therapies for cutaneous SCC.

Aberrant expression of microRNAs plays vital roles in tumor development and progression. As transcription factors (TFs) are the critical components of signaling cascades, specific targeting effects of microRNAs to specific TFs may determine the role of microRNAs in different cancers. In this study, we identified Nuclear Factor I/B (NFIB) as one of the targets of miR-365 which was previously verified as an onco-miR in cutaneous squamous cell carcinoma (CSCC). Down-regulation of NFIB was a general feature in both CSCC cell lines and tumors from patients which show drastically up-regulated miR-365 expression levels. The siRNA-based knockdown of NFIB mimic the carcinogenic transformation of normal cells by ectopically expression of miR-365 which indicates depletion of NFIB is necessary for miR-365 to exert its pro-carcinogenic function. NFIB may represent a functional barrier targeted by miR-365 to the development of CSCC. Further studies also discovered a conserved feedback regulatory circuitry formed by NFIB and miR-365 in CSCC development which may be potentially utilized as therapeutic target to improve the clinical CSCC treatment.

MicroRNAs (miRNAs) are known as a kind of small, noncoding RNA, which play an important role in mediating many biological processes such as development, cell proliferation and differentiation in plants and animals. Here we report the differential expression profiles of miRNAs and characterized putative target genes in NIH3T3 cells at a series of different time points after UVB irradiation (compared with no UVB irradiation). The relative expression of mature miRNA genes was determined by miRNA microarray technique and the results were confirmed by real-time reverse transcriptase polymerase chain reaction (qRT-PCR). Potential target genes of these miRNAs were classified into different function categories with the GOstat software (http://gostat.wehi.edu.au/cgi-bin/goStat.pl). Several miRNAs in this study expressed highly at different time points, especially mmu-miR-365 and mmu-miR-21. Three miRNAs were lowly expressed, of which mmu-miR-465 showed low levels of expression at all time points, whereas after 50 J m(-2) UVB irradiation mmu-miR-296 and mmu-miR-376c showed low levels of expression at 6 and 12 h, respectively. Our study provided a basis for the global characterization of UV-regulated miRNA expression.

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Aberrant expression of the epidermal growth factor receptor (EGFR) plays vital roles in tumor development and progression. In the present study, ultraviolet irradiation induced the upregulation of EGFR in skin-derived keratinocytes, which may contribute to the development of cutaneous squamous cell carcinoma (CSCC). This was supported by the high expression of EGFR in CSCC clinical samples. Treating A431 CSCC cells with gefitinib, a tyrosine kinase inhibitor, activated the intrinsic mitochondrial apoptotic pathway while inducing protective autophagy. Combined application of chloroquine with gefitinib enhanced the treatment efficacy of gefitinib against CSCC by inhibiting autophagic flux. These findings demonstrated that autophagy inhibition may be an effective strategy for enhancing the sensitivity of EGFR-expressing cells to tyrosine kinase inhibitor treatment. Manipulating pro-survival autophagy by the combined application of chloroquine with gefitinib is a promising approach for improving the efficacy of EGFR inhibitors in cancer treatment. This may contribute to novel EGFR-targeted therapeutic strategies in the near future.