The membrane mucin MUC4 is elevated in breast tumor lymph node metastases relative to matched primary tumors and confers aggressive properties to breast cancer cells

Abstract Introduction Previous studies indicate that overexpression of the membrane-associated mucin MUC4 is potently anti-adhesive to cultured tumor cells, and suppresses cellular apoptotic response to a variety of insults. Such observations raise the possibility that MUC4 expression could contribute to tumor progression or metastasis, but the potential involvement of MUC4 in breast cancer has not been rigorously assessed. The present study aimed to investigate the expression of the membrane mucin MUC4 in normal breast tissue, primary breast tumors and lymph node metastases, and to evaluate the role of MUC4 in promoting the malignant properties of breast tumor cells. Methods MUC4 expression levels in patient-matched normal and tumor breast tissue was initially examined by immunoblotting lysates of fresh frozen tissue samples with a highly specific preparation of anti-MUC4 monoclonal antibody 1G8. Immunohistochemical analysis was then carried out using tissue microarrays encompassing patient-matched normal breast tissue and primary tumors, and patient-matched lymph node metastases and primary tumors. Finally, shRNA-mediated knockdown was employed to assess the contribution of MUC4 to the cellular growth and malignancy properties of JIMT-1 breast cancer cells. Results Immunoblotting and immunohistochemistry revealed that MUC4 levels are suppressed in the majority (58%, p < 0.001) of primary tumors relative to patient-matched normal tissue. On the other hand, lymph node metastatic lesions from 37% (p < 0.05) of patients expressed higher MUC4 protein levels than patient-matched primary tumors. MUC4-positive tumor emboli were often found in lymphovascular spaces of lymph node metastatic lesions. shRNA-mediated MUC4 knockdown compromised the migration, proliferation and anoikis resistance of JIMT-1 cells, strongly suggesting that MUC4 expression actively contributes to cellular properties associated with breast tumor metastasis. Conclusions Our observations suggest that after an initial loss of MUC4 levels during the transition of normal breast tissue to primary tumor, the re-establishment of elevated MUC4 levels confers an advantage to metastasizing breast tumor cells by promoting the acquisition of cellular properties associated with malignancy

Consumption of Green Tea Extract Results in Osteopenia in Growing Male Mice1–3

Consumption of green tea may reduce body weight gain. Although many disorders are related to obesity, bone mass is positively correlated with body mass. Therefore, our purpose in this study was to determine the effects of green tea extract (GTE) on bone mass and architecture in rapidly growing lean [C57BL/6 wild type (WT)] and genetically obese, leptin-deficient (ob/ob) male mice. Five-week-old lean and ob/ob mice were assigned to diets containing GTE at 0, 1, or 2% for 6 wk. Femoral and lumbar vertebral bone volume and architecture were evaluated by micro-computed tomography (μCT). Following μCT analysis, femora were ashed to determine bone mineral content and density. Compared with WT mice, ob/ob mice had shorter femora (P < 0.001), lower femoral bone volume (P < 0.001), and lower femoral bone mineral content (P < 0.001), but higher cancellous bone volume in lumbar vertebrae (P < 001). Neither genotype nor treatment affected femoral bone mineral density, indicating normal mineralization. GTE consumption resulted in lower femur length, volume, mineral content, cortical volume, and cortical thickness (P < 0.001), as well as lower cancellous bone volume/tissue volume (P < 0.008) and trabecular thickness (P < 0.004) in lumbar vertebrae. The results indicate that leptin is not essential for the reduced gains in body weight and bone mass due to GTE in growing mice and suggest that consumption of large quantities of green tea may reduce the rate of bone accumulation during growth