Altered gene expression in breast cancer liver metastases

• Published in: International journal of cancer 2009-04, Vol.124 (7), p.1503-1516
• Main Authors: Erin, Nuray, Wang, Ning, Xin, Ping, Bui, Voung, Weisz, Judith, Barkan, Guliz A., Zhao, Wei, Shearer, Debra, Clawson, Gary A.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; breast cancer; Breast Neoplasms - genetics; Breast Neoplasms - pathology; Cell Adhesion Molecules - biosynthesis; Cell Adhesion Molecules - genetics; Cell Line, Tumor; claudins; Female; gene array; Gene Expression; Gene Expression Profiling; Gynecology. Andrology. Obstetrics; Immunoblotting; immunocytochemistry; Immunohistochemistry; liver metastases; Liver Neoplasms - pathology; Liver Neoplasms - secondary; Mammary gland diseases; Medical sciences; Mice; Mice, Inbred BALB C; Neoplasm Invasiveness - genetics; Neoplasm Metastasis - genetics; Oligonucleotide Array Sequence Analysis; QPCR; Reverse Transcriptase Polymerase Chain Reaction; Tumors; ZO‐1; γ‐catenin
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.24131

We previously developed a highly aggressive cell line from heart metastases of 4T1 breast carcinoma (designated 4THM), which produced liver metastases (designated 4TLM). In this study, gene array analysis (GAEA) compared gene expression profiles in 4TLM with profiles in 4T1 and 4THM primary tumors. GAEA demonstrated that 4T1 and 4THM tumors differed in about 250 genes. Over 1,000 genes, however, were expressed differently in 4TLM compared with primary tumors. A cohort of 16 genes showed significantly decreased expression in 4THM tumors, which decreased even further in 4TLM. Many of these genes have been implicated in breast cancer, and many are involved in cell adhesion and junctional complexes. Expression of multiple tight and adherence junction proteins was either downregulated or disappeared in 4TLM; downregulation of claudin 4, claudin 7 and γ‐catenin was confirmed by quantitative polymerase chain reaction, immunoblot, and immunocytochemical (ICC) analyses. At the protein level, intact ZO‐1 was also observed in 4T1 tumors, but was not expressed in 4THM or 4TLM tumors. ICC demonstrated expression of γ‐catenin at the plasma membrane with 4T1 tumors, whereas staining appeared to be nuclear/perinuclear in 4THM tumors. Claudin 7 staining was also seen in monocyte/pmacrophage‐like cells in liver around metastatic lesions by ICC, and it appeared that larger 4TLM tumors apparently reexpressed claudin 7 RNA and protein. Our results demonstrate that decreased or abnormal expression of a number of cell adhesion/junctional proteins, including claudin 4, 7, ZO‐1 and γ‐catenin, correlates with liver metastases, and that cell adhesion molecules in the microenvironment are also altered. © 2008 Wiley‐Liss, Inc.