Critical role of miR-10b in B-RafV600E dependent anchorage independent growth and invasion of melanoma cells.

Recent high-throughput-sequencing of cancer genomes has identified oncogenic mutations in the B-Raf genetic locus as one of the critical events in melanomagenesis. B-Raf encodes a serine/threonine kinase that regulates the MAPK/ERK kinase (MEK) and extracellular signal-regulated kinase (ERK) protein kinase cascade. In normal cells, the activity of B-Raf is tightly regulated and is required for cell growth and survival. B-Raf gain-of-function mutations in melanoma frequently lead to unrestrained growth, enhanced cell invasion and increased viability of cancer cells. Although it is clear that the invasive phenotypes of B-Raf mutated melanoma cells are stringently dependent on B-Raf-MEK-ERK activation, the downstream effector targets that are required for oncogenic B-Raf-mediated melanomagenesis are not well defined. miRNAs have regulatory functions towards the expression of genes that are important in carcinogenesis. We observed that miR-10b expression correlates with the presence of the oncogenic B-Raf (B-RafV600E) mutation in melanoma cells. While expression of miR-10b enhances anchorage-independent growth of B-Raf wild-type melanoma cells, miR-10b silencing decreases B-RafV600E cancer cell invasion in vitro. Importantly, the expression of miR-10b is required for B-RafV600E-mediated anchorage independent growth and invasion of melanoma cells in vitro. Taken together our results suggest that miR-10b is an important mediator of oncogenic B-RafV600E activity in melanoma.

Intraoperative Ultrasound-Guided Excision of Nonpalpable Breast Lesions.

In order to determine if intraoperative ultrasound (US)-guided excision is a feasible procedure, we prospectively studied 15 female patients between July 1996 and December 1998 for US-detected nonpalpable breast lesions. Intraoperative US was used by the operating surgeon to identify the lesion, guide its excision, and evaluate the specimen to document complete removal. A control group of 15 female patients with mammographically detected nonpalpable lesions was used for comparison. These patients underwent preoperative needle localization, excision of the lesions, and specimen radiographs. Age, size of the lesion, total excised tissue volume, and operative time were documented in all cases. Fifteen patients aged 20-83 years (mean 51) underwent US-guided excision, which adequately localized all lesions, and excision was successful in all patients. Specimen US documented the lesion in all cases. Lesion size ranged from 0.7 to 2 cm (mean 1.1) and the total excised tissue volume averaged 30 cc. Mean operative time was 53 minutes (range 30-75 minutes). The 15 patients of the control group ranged in age from 32 to 82 years (mean 61). Excision was successful in all cases. Lesion size ranged from 1 to 2.5 cm (average 1.5) and the average excised tissue volume was 35 cc. Mean operative time was 50 minutes (range 30-75 minutes). There were no statistically significant differences between the two groups with regard to age (p = 0.2), operative time (p = 0.5), and total excised tissue volume (p = 0.5). The size of the lesions did have a statistically significant difference (p = 0.01). There were no perioperative complications. In conclusion, US-guided excision of nonpalpable breast lesions is a feasible and effective technique. US documents results immediately, is of minimal discomfort to the patient, avoids the need for preoperative localization, allows the entire procedure to be performed in the operating room, does not require radiation, and provides the surgeon with a useful alternative in selected cases.