Ectopic expression of PLC-ß2 in non-invasive breast tumor cells plays a protective role against malignant progression and is correlated with the deregulation of miR-146a.

Cells in non-invasive breast lesions are widely believed to possess molecular alterations that render them either susceptible or refractory to the acquisition of invasive capability. One such alteration could be the ectopic expression of the ß2 isoform of phosphoinositide-dependent phospholipase C (PLC-ß2), known to counteract the effects of hypoxia in low-invasive breast tumor-derived cells. Here, we studied the correlation between PLC-ß2 levels and the propensity of non-invasive breast tumor cells to acquire malignant features. Using archival FFPE samples and DCIS-derived cells, we demonstrate that PLC-ß2 is up-regulated in DCIS and that its forced down-modulation induces an epithelial-to-mesenchymal shift, expression of the cancer stem cell marker CD133, and the acquisition of invasive properties. The ectopic expression of PLC-ß2 in non-transformed and DCIS-derived cells is, to some extent, dependent on the de-regulation of miR-146a, a tumor suppressor miRNA in invasive breast cancer. Interestingly, an inverse relationship between the two molecules, indicative of a role of miR-146a in targeting PLC-ß2, was not detected in primary DCIS from patients who developed a second invasive breast neoplasia. This suggests that alterations of the PLC-ß2/miR-146a relationship in DCIS may constitute a molecular risk factor for the appearance of new breast lesions. Since neither traditional classification systems nor molecular characterizations are able to predict the malignant potential of DCIS, as is possible for invasive ductal carcinoma (IDC), we propose that the assessment of the PLC-ß2/miR-146a levels at diagnosis could be beneficial for identifying whether DCIS patients may have either a low or high propensity for invasive recurrence.

Levels of miR-126 and miR-218 are elevated in ductal carcinoma in situ (DCIS) and inhibit malignant potential of DCIS derived cells.

A substantial number of ductal carcinoma in situ (DCIS) detected by mammography never progress to invasive ductal carcinoma (IDC) and current approaches fail to identify low-risk patients not at need of adjuvant therapies. We aimed to identify the key miRNAs protecting DCIS from malignant evolution, that may constitute markers for non-invasive lesions. We studied 100 archived DCIS samples, including pure DCIS, DCIS with adjacent IDC and pure DCIS from patients with subsequent IDC in contralateral breast or no recurrence. A DCIS derived cell line was used for molecular and cellular studies. A genome wide study revealed that pure DCIS has higher miR-126 and miR-218 expression than DCIS with adjacent IDC lesions or than IDC. The down-regulation of miR-126 and miR-218 promoted invasiveness in vitro and, in patients with pure DCIS, was associated with later onset of IDC. Survival studies of independent cohorts indicated that both miRNAs play a protective role in IDC. The clinical findings are in agreement with the miRNAs' roles in cell adhesion, differentiation and proliferation. We propose that miR-126 and miR-218 have a protective role in DCIS and represent novel biomarkers for the risk assessment in women with early detection of breast cancer.

Malignant fibrous histiocytoma and fibrosarcoma of bone: a re-assessment in the light of currently employed morphological, immunohistochemical and molecular approaches.

Malignant fibrous histiocytoma (MFH) and fibrosarcoma (FS) of bone are rare malignant tumours and contentious entities. Sixty seven cases labelled as bone MFH (57) and bone FS (10) were retrieved from five bone tumour referral centres and reviewed to determine whether recent advances allowed for reclassification and identification of histological subgroups with distinct clinical behaviour. A panel of immunostains was applied: smooth muscle actin, desmin, h-caldesmon, cytokeratin AE1-AE3, CD31, CD34, CD68, CD163, CD45, S100 and epithelial membrane antigen. Additional fluorescence in situ hybridisation and immunohistochemistry were performed whenever appropriate. All cases were reviewed by six bone and soft tissue pathologists and a consensus was reached. Follow-up for 43 patients (median 42 months, range 6-223 months) was available. Initial histological diagnosis was reformulated in 18 cases (26.8 %). Seven cases were reclassified as leiomyosarcoma, six as osteosarcoma, three as myxofibrosarcoma and one each as embryonal rhabdomyosarcoma and interdigitating dendritic cell sarcoma. One case showed a peculiar biphasic phenotype with epithelioid nests and myofibroblastic spindle cells. Among the remaining 48 cases, which met the WHO criteria for bone FS and bone MFH, we identified five subgroups. Seven cases were reclassified as undifferentiated pleomorphic sarcoma (UPS) and 11 as UPS with incomplete myogenic differentiation due to positivity for at least one myogenic marker. Six were reclassified as spindle cell sarcoma not otherwise specified. Among the remaining 24 cases, we identified a further two recurrent morphologic patterns: eight cases demonstrated a myoepithelioma-like phenotype and 16 cases a myofibroblastic phenotype. One of the myoepithelioma-like cases harboured a EWSR1-NFATC2 fusion. It appears that bone MFH and bone FS represent at best exclusion diagnoses.