MiR-671-5p is encoded by a gene localized at 7q36.1, a region amplified in human glioblastoma multiforme (GBM), the most malignant brain cancer. To investigate whether expression of miR-671-5p were altered in GBM, we analyzed biopsies from a cohort of forty-five GBM patients and from five GBM cell lines. Our data show significant overexpression of miR-671-5p in both biopsies and cell lines. By exploiting specific miRNA mimics and inhibitors, we demonstrated that miR-671-5p overexpression significantly increases migration and to a less extent proliferation rates of GBM cells. Through a combined in silico and in vitro approach, we identified CDR1-AS, CDR1, VSNL1 as downstream miR-671-5p targets in GBM. Expression of these genes significantly decreased both in GBM biopsies and cell lines and negatively correlated with that of miR-671-5p. Based on our data, we propose that the axis miR-671-5p / CDR1-AS / CDR1 / VSNL1 is functionally altered in GBM cells and is involved in the modification of their biopathological profile.

The mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway has a master control role in various cancer-related biological processes as cell growth, proliferation, differentiation, migration, and apoptosis. It also regulates many transcription factors that control microRNAs (miRNAs) and their biosynthetic machinery. To investigate on the still poorly characterised global involvement of miRNAs within the pathway, we profiled the expression of 745 miRNAs in three colorectal cancer (CRC) cell lines after blocking the pathway with three different inhibitors. This allowed the identification of two classes of post-treatment differentially expressed (DE) miRNAs: (1) common DE miRNAs in all CRC lines after treatment with a specific inhibitor (class A); (2) DE miRNAs in a single CRC line after treatment with all three inhibitors (class B). By determining the molecular targets, biological roles, network position of chosen miRNAs from class A (miR-372, miR-663b, miR-1226*) and class B (miR-92a-1*, miR-135b*, miR-720), we experimentally demonstrated that they are involved in cell proliferation, migration, apoptosis, and globally affect the regulation circuits centred on MAPK/ERK signaling. Interestingly, the levels of miR-92a-1*, miR-135b*, miR-372, miR-720 are significantly higher in biopsies from CRC patients than in normal controls; they also are significantly higher in CRC patients with mutated KRAS than in those with wild-type genotypes (Wilcoxon test, p < 0.05): the latter could be a downstream effect of ERK pathway overactivation, triggered by KRAS mutations. Finally, our functional data strongly suggest the following miRNA/target pairs: miR-92a-1*/PTEN-SOCS5; miR-135b*/LATS2; miR-372/TXNIP; miR-663b/CCND2. Altogether, these results contribute to deepen current knowledge on still uncharacterized features of MAPK/ERK pathway, pinpointing new oncomiRs in CRC and allowing their translation into clinical practice and CRC therapy.

The relationship between therapeutic response and modifications of microRNA (miRNA) transcriptome in colorectal cancer (CRC) remains unknown. We investigated this issue by profiling the expression of 667 miRNAs in 2 human CRC cell lines, one sensitive and the other resistant to cetuximab (Caco-2 and HCT-116, respectively), through TaqMan real-time PCR. Caco-2 and HCT-116 expressed different sets of miRNAs after treatment. Specifically, 21 and 22 miRNAs were differentially expressed in Caco-2 or HCT-116, respectively (t test, P < 0.01). By testing the expression of differentially expressed miRNAs in CRC patients, we found that miR-146b-3p and miR-486-5p are more abundant in K-ras-mutated samples with respect to wild-type ones (Wilcoxon test, P < 0.05). Sixty-seven percent of differentially expressed miRNAs were involved in cancer, including CRC, whereas 19 miRNA targets had been previously reported to be involved in the cetuximab pathway and CRC. We identified 25 transcription factors putatively controlling these miRNAs, 11 of which have been already reported to be involved in CRC. On the basis of these data, we suggest that the downregulation of let-7b and let-7e (targeting K-ras) and the upregulation of miR-17* (a CRC marker) could be considered as candidate molecular markers of cetuximab resistance. Global network functional analysis (based on miRNA targets) showed a significant overrepresentation of cancer-related biological processes and networks centered on critical nodes involved in epidermal growth factor receptor internalization and ubiquitin-mediated degradation. The identification of miRNAs, whose expression is linked to the efficacy of therapy, should allow the ability to predict the response of patients to treatment and possibly lead to a better understanding of the molecular mechanisms of drug response.

We report on two cases of myofibroblastoma (MFB) of the breast comprised predominantly of a mature fatty component, representing approximately three quarters of the entire tumour area. Both tumours consisted of a well-circumscribed lipomatous tumour mass containing dispersed nodular or irregularly shaped spindled cellular areas. The fatty component was represented exclusively by mature adipocytes, uniform in size and shape, lacking nuclear pleomorphism. The cellular areas contained spindly to oval cells with morphological and immunophenotypical features typical of MFB. The two components were so intimately admixed that a finger-like infiltrating growth pattern was apparent. The cases reported here as "lipomatous MFB" aim to clarify further the morphological spectrum of MFB of the breast. Lipomatous MFB may potentially mimic other benign or aggressive tumour-like lesions or even bland-looking malignant spindle cell tumours such as fibromatosis, nodular fasciitis, spindle cell lipoma, spindle cell liposarcoma, spindle cell variant of metaplastic carcinoma, spindle cell malignant myoepithelioma, and low-grade fibrosarcoma/malignant fibrous histiocytoma. The histogenesis of the present bimorphic mesenchymal tumours could be explained as the result of a dual, myofibroblastic and lipomatous, differentiation from a common pluripotential mesenchymal precursor cell, probably represented by the vimentin+/CD34+ fibroblast of the mammary stroma.