Alterations in Cx43 and OB-cadherin affect breast cancer cell metastatic potential

Emerging evidence suggests that gap junctional intercellular communication (GJIC) and expression of connexins (Cx) contribute to the metastatic potential of breast cancer cells. To more directly address this, an aggressive bone metastasis breast cancer cell line, MDA-MET (MET), was stably transfected with human Cx43 cDNA (MET/Cx43⁺). Focusing on clone 28 of MET/Cx43⁺, we demonstrated that GJIC, Cx43 protein and Cx43 mRNA were significantly increased in MET/Cx43⁺ cells relative to MET, the plasmid control for the Cx43 transfectants (MET/HY) and a metastatic breast cancer cell that is less metastatic to bone than MET, MDA-MB-231. Cx26 mRNA was also increased in MET/Cx43⁺ clone 28 cells while mRNA for Cx32, Cx37, Cx40 and Cx45 were not detected in any of the breast cancer cell lines examined. MET/Cx43⁺ clone 28 invasiveness was decreased by 33% relative to MET/HY, while their ability to migrate was unchanged. The ability of MET/Cx43⁺ clone 28 cells to adhere to hFOB and HUV-EC-C cells was decreased approximately 30% and 70%, respectively, relative to MET and MET/HY. E-cadherin and N-cadherin proteins were not detected in MET, MDA-MB-231, MET/Cx43⁺ clone 28 and MET/HY cells. However, OB-cadherin protein levels were decreased approximately 43% in MET/Cx43⁺ clone 28 relative to MET/HY cells. These findings suggest that GJIC and Cx43 expression contribute to breast cancer cell adhesion and migration, possibly through a mechanism involving OB-cadherin, and these changes in turn regulate the metastatic potential of breast cancer cells, especially to bone.     

Alterations of gene expression in the development of early hyperplastic precursors of breast cancer

Enlargement of normal terminal duct lobular units (TDLUs) by hyperplastic columnar epithelial cells is one of the most common abnormalities of growth in the adult female human breast. These hyperplastic enlarged lobular units (HELUs) are important clinically as the earliest histologically identifiable potential precursor of breast cancer. The causes of the hyperplasia are unknown but may include estrogen-simulated growth mediated by estrogen receptor-alpha, which is highly elevated in HELUs and may be fundamental to their development. The present study used DNA microarray technology and RNA from microdissected pure epithelial cells to examine changes in gene expression and molecular pathways associated with the development of HELUs from TDLUs. The results suggest that HELUs evolve from TDLUs primarily by reactivation of pathways involved in embryonic development and suppression of terminal differentiation. Changes in ERBB genes were particularly prominent, including a uniform switch in ligands for the ERBB1 receptor (14-fold decrease in epidermal growth factor and 10-fold increase in amphiregulin, respectively) in HELUs compared with TDLUs. Epidermal growth factor regulates terminal differentiation in adult breast and amphiregulin is critical to normal embryonic breast development. Because HELUs are such early potential precursors of breast cancer, targeting some of these alterations may be especially promising strategies for breast cancer prevention.     

侵袭性骨肿瘤中RB基因及其蛋白产物表达的研究

目的探讨抑癌基因ＲＢ的改变与骨肿瘤的关系。方法采用地高辛标记的ＲＢｃＤＮＡ探针对３４例侵袭性骨肿瘤组织及同体正常软组织进行ＳｏｕｔｈｅｒｎＢｌｏｔ检测，同时应用ＬＳＡＢ免疫组化法对９９例侵袭性骨肿瘤及１４例瘤旁软组织进行ＲＢ蛋白表达的检测。结果２１例骨肉瘤中有９例可检出ＲＢ基因的结构异常（４２．９％），ＲＢ蛋白的缺失仅在２６．９％（７／２６）的骨肉瘤和２１．７％（５／２３）的软骨肉瘤中检测到，良性的骨巨细胞瘤和软骨母细胞瘤中未检出ＲＢ蛋白的缺失，其二者差异有意义（Ｐ＜０．０５）；分化差、异型性明显的骨肉瘤细胞其ＲＢ蛋白表达为阴性，低分化的软骨肉瘤及间叶性软骨肉瘤其ＲＢ蛋白亦多为阴性。结论ＲＢ基因结构的异常、ＲＢ蛋白的缺失，可能与骨的恶性肿瘤的发生及其演进有关。     

Appendicular metastatic involvement in breast cancer

The paper describes a case of appendicular metastatic involvement in breast cancer. The 60-year-old female patient developed the signs of acute appendicitis 18 years after detection of primary tumor; after appendectomy the intraoperative appendular specimens exhibited trains of tumor cells that infiltrated the mid- and lower muscle layer third. Immunohistochemical study revealed a moderate expression of Er and Pgr receptors (150 H scores), a positive reaction with EMA, K7, K6, and lactoalbumin The authors review the data available in the literature on the specific features of metastatic spread into the appendix and on management tactics in these patients.     

Osteopontin gene expression determines spontaneous metastatic performance of orthotopic human breast cancer xenografts

A major problem in the therapeutic management of cancer is the growth of metastases in distant organs, but the genes orchestrating the process need to be identified for the rational design of new treatment. Here, we provide decisive experimental evidence demonstrating the causal involvement of a specific gene, osteopontin (OPN), in the pathogenesis of metastasis by human breast cancer cells and implicating some of its probable partners. Stable long-term depletion, or up-regulation, of OPN gene expression in a matched, isogenic pair of human breast cancer cell lines of differing metastatic proficiency reproducibly changed their ability to colonize distant organs. OPN down-regulation was achieved by transduction of the metastatic line with a DNA construct encoding a small hairpin RNA in a vector labeled with red fluorescent protein and resulted in a marked reduction of metastatic load (P < 0.01). Up-regulation of OPN in the negligibly metastatic line, with a green fluorescent protein-marked retroviral vector containing OPN cDNA driven by a strong promoter, resulted in heavy colonization of the lungs and lymph nodes (P < 0.005). The reciprocal changes in behavior of these matched cell lines cross-corroborate each other. Concomitant changes were seen in the expression of other metastasis-related genes in both modulated lines. The data indicate that therapeutic targeting of tumor OPN molecules could reset metastatically relevant gene networks, resulting in clinical benefit.     

Changes in retinoblastoma gene expression during cervical cancer progression

The role of tumour suppressor genes in the development of human cancers has been studied extensively. In viral carcinogenesis, the inactivation of suppressor proteins such as retinoblastoma (pRb) and p53, and cellular oncogenes overexpression, such as c-myc, has been the subject of a number of investigations. In uterine-cervix carcinomas, where high-risk human papillomavirus (HPV) plays an important role, pRb and p53 are inactivated by E7 and E6 viral oncoproteins, respectively. However, little is known about the in situ expression of some of these proteins in pre-malignant and malignant cervical tissues. On the other hand, it has also been demonstrated that c-myc is involved in cervical carcinogenesis, and that pRb participates in the control of c-myc gene expression. By using immunostaining techniques, we investigated pRb immunodetection pattern in normal tissues, squamous intraepithelial lesions (SILs) and invasive carcinomas from the uterine cervix. Our data show low pRb detection in both normal cervical tissue and invasive lesions, but a higher expression in SILs. C-Myc protein was observed in most of the cellular nuclei of the invasive lesions, while in SILs was low. These findings indicate a heterogeneous pRb immunostaining during the different stages of cervical carcinogenesis, and suggest that this staining pattern could be a common feature implicated in the pathogenesis of uterine-cervix carcinoma.     

Loss of retinoblastoma gene and amplification of N-myc gene in retinoblastoma.

We have analyzed paired samples of genomic DNA from peripheral leukocyte and primary tumor tissue from nine patients with retinoblastoma (RB) and from two RB cell lines, WERI-Rb-1 and Y79, to detect the molecular alterations of the retinoblastoma susceptibility gene (RB-1) and N-myc gene. In Southern analysis, RB-1 deletions in tumor tissues were detected in five patients (56%), one of these revealed a total loss of RB-1. N-myc amplification was found only in one (11.1%) out of nine patients. We also observed a total loss of RB-1 in WERI-Rb-1, and a more than 100-fold amplification of N-myc in Y79. The analysis of the relationship between molecular events and clinical characteristics such as age, sex, tumor laterality did not reveal any specific correlation. These results suggest that genetic backgrounds of RB in Korean patients are quite similar to those of reported cases elsewhere. The high sensitivity of our method in detecting the RB-1 loss indicates that this method can be a useful tool for initially screening a large number of tumors.     

Polychemotherapeutic treatment of patients with metastatic breast cancer

A total of 79 metastatic breast cancer patients were treated with a combination of vincristine, doxorubicin and cyclophosphamide (VDC). In 59% of the patients remission occurred, in 23% the condition did not change, while in 18% progression of the disease was observed. The mean duration of the remission was 11 months. The side-effects did practically not influence the course of the treatment.