Rearrangements involving the RET protooncogene have been implicated in the development of papillary thyroid carcinoma (PC). Transgenic mice, expressing thyroid-targeted RET/PTC-1, develop PC; but the clinical significance of this oncogene remains uncertain. We examined the expression of RET/PTC-1, -2, and -3 in human thyroid microcarcinomas and clinically evident PC to determine its role in early stage vs. developed PC and to examine the diversity of RET/PTC in multifocal disease. RNA was extracted from paraffin-embedded microcarcinomas and clinically evident PCs; the results obtained from paraffin-embedded tissue were confirmed on RNA from corresponding snap-frozen tissue of clinically evident PCs. RT and PCR was performed using primers for RET/PTC-1, -2, and -3; PGK-1 (the housekeeping gene) analysis was used to ensure integrity of the RNA and efficiency of the RT reaction. PCR products were resolved by gel electrophoresis, and Southern hybridization was performed with RET/PTC-1, -2, and -3 probes. A polyclonal antibody to the carboxyterminus of RET was used for immunohistochemistry on paraffin sections. Thirty-nine occult papillary thyroid microcarcinomas from 21 patients were analyzed. Of the 30 tumors (77%) positive for RET/PTC rearrangements, 12 were positive for RET/PTC-1, 3 for RET/ PTC-2, 6 for RET/PTC-3, and 9 for multiple RET/PTC oncogenes. In clinically evident tumors, 47% had RET/PTC rearrangements. Immunohistochemistry demonstrated close correlation with RT-PCR-derived findings. RET/PTC expression is highly prevalent in microcarcinoma and occurs more frequently than in clinically evident PC (P < 0.005). Multifocal disease, identified in 17 of the 21 patients, exhibited identical RET/PTC rearrangements within multiple tumors in only 2 patients; the other 15 patients had diverse rearrangements in individual tumors. Our results indicate that RET/PTC oncogene rearrangements may play a role in early-stage papillary thyroid carcinogenesis, but they seem to be less important in determining progression to clinically-evident disease. In multifocal disease, the diversity of RET/PTC profiles, in the majority of cases, suggests that individual tumors arise independently in a background of genetic or environmental susceptibility.

Here we report that miR-93, a miRNA in the miR-106B~25 cluster, a paralog of the miR-17–92 cluster, was significantly upregulated in human breast carcinoma tissues. We stably expressed miR-93 in the MT-1 human breast carcinoma cell line and found that tumors formed by the miR-93 cells contained more blood vessels than those formed by the control cells. Co-culture experiments indicated that the MT-1 cells displayed a high activity of adhesion with endothelial cells and could form larger and more tube-like structures with endothelial cells. Lung metastasis assays were performed in a mouse metastatic model, and it was found that expression of miR-93 promoted tumor cell metastasis to lung tissue. In cell culture, expression of miR-93 enhanced cell survival and invasion. We examined the potential target that mediated miR-93’s effects and found that the large tumor suppressor, homology 2 (LATS2) was a target of miR-93. Higher levels of LATS2 were associated with cell death in the tumor mass. Silencing LATS2 expression promoted cell survival, tube formation and invasion, while ectopic expression of LATS2 decreased cell survival and invasion. These findings demonstrated that miR-93 promoted tumor angiogenesis and metastasis by suppressing LATS2 expression. Our results suggest that the inhibition of miR-93 function may be a feasible approach to repress tumor metastasis.

SummaryMicroRNAs are known to play regulatory roles in gene expression associated with cancer development. We analyzed levels of the microRNA miR-24 in patients with breast carcinoma and found that miR-24 was higher in breast carcinoma samples than in benign breast tissues. We generated constructs expressing miR-24 and studied its functions using both in vitro and in vivo techniques. We found that the ectopic expression of miR-24 promoted breast cancer cell invasion and migration. In vivo experiments in mice indicated that the expression of miR-24 enhanced tumor growth, invasion into local tissues, metastasis to lung tissues and decreased overall mouse survival. In the miR-24-expressing cells and tumors, EGFR was highly phosphorylated, whereas expression of the phosphatases tyrosine-protein phosphatase non-receptor type 9 (PTPN9) and receptor-type tyrosine-protein phosphatase F (PTPRF) were repressed. We confirmed that miR-24 could directly target both PTPN9 and PTPRF. Consistent with this, we found that the levels of phosphorylated epidermal growth factor receptor (pEGFR) were higher whereas the levels of PTPN9 and PTPRF were lower in the patients with metastatic breast carcinoma. Ectopic expression of PTPN9 and PTPRF decreased pEGFR levels, cell invasion, migration and tumor metastasis. Furthermore, we found that MMP2, MMP11, pErk, and ADAM15 were upregulated, whereas TIMP2 was downregulated; all of which supported the roles of miR-24 in tumor invasion and metastasis. Our results suggest that miR-24 plays a key role in breast cancer invasion and metastasis. miR-24 could potentially be a target for cancer intervention.

Background The size of abnormal parathyroid glands in patients with primary hyperparathyroidism is highly variable, but the clinical significance of giant glands is unknown. Methods 300 consecutive patients were reviewed following parathyroidectomy for primary hyperparathyroidism. We compared patients with giant parathyroid adenomas (weight ≥95th percentile) with the remaining patients. Results Giant adenomas were defined as weight ≥95th percentile or 3.5 grams (median 0.61 g, range 0.05–29.93). Patients with giant adenomas had a higher mean preoperative calcium level, higher mean parathyroid hormone level, and were less likely to have multiglandular or symptomatic disease. Giant adenomas were successfully localized on imaging in 87% of patients, which was not significantly increased over other patients (82%). There were no differences between the groups in age, gender, gland location, or the incidence of persistent or recurrent hyperparathyroidism. Finally, giant glands had an increased incidence of symptomatic post-operative hypocalcemia including one patient who required rehospitalization following removal of a giant gland. Conclusions Giant parathyroid adenomas have a distinct presentation characterized by single gland disease and lower incidence of symptoms despite increased levels of calcium and parathyroid hormone. Additionally, following resection of a giant adenoma, patients are more likely to develop symptomatic hypocalcemia.

This is the first report to show that overexpression of breast cancer-associated genes in breast cancer subjects with pathology-negative ALN correlates with traditional indicators of disease prognosis. These interim results provide strong evidence that molecular markers could serve as valid surrogates for the detection of occult micrometastases in ALN. Correlation of real-time RT-PCR analyses with disease-free survival in this patient cohort will help to define the clinical relevance of micrometastatic disease in this patient population.