Abstract. The CCN3/nephroblastoma overexpressed gene belongs to the CCN family of genes that encode secreted proteins involved in a variety of processes including tumorigenesis. Altered expression of CCN3 has been observed in human nephroblastoma and renal cell carcinoma (RCC), suggesting that CCN3 plays a role in kidney tumorigenesis. The aim of the present study was to examine the role of CCN3 in clear cell RCC biology. In particular, we studied the expression of CCN3 in 32 pairs of RCC tissues and corresponding normal kidney tissues using immunohistochemistry. The CCN3 gene was transfected into the 786-O cell line and the behaviors of stably transfected clones were analyzed. Results showed the expression of CCN3 was lower in RCC tissues compared to corresponding normal kidney tissues and the expression of CCN3 was inversely correlated with the Ki67 index. CCN3-expressing clones exhibited significantly inhibited cell proliferation. Furthermore, CCN3-transfected 786-O cells exhibited increased adhesion to extracellular matrix proteins, migration and invasion in Matrigel. Our data indicated that CCN3 plays an anti-proliferative role in clear cell RCC cells and promotes the adhesion, migration and invasion of clear cell RCC cells.
IntroductionRenal cell carcinoma (RCC) is the most common type of cancer of the kidney. Metastasis frequently becomes evident at the time of diagnosis or patients develop distant metastases following removal of the primary tumor. The treatment of metastatic, locally unresectable RCCs remains a challenge for urologists (1). There is a great need to understand the basic biology of RCC and develop better therapeutic options.The CCN3 (nephroblastoma overexpressed, NOV) gene belongs to the CCN family of genes, which has five additional members: cystein-rich protein 61 (Cyr61), connective tissue growth factor (CTGF), Wnt-1-induced secreted protein (WISP)-1, WISP-2 and WISP-3. CCN proteins are involved in fundamental biological processes such as cell proliferation, attachment, migration, differentiation, wound healing, angiogenesis and tumorigenesis (2).The CCN3 protein is detectable at varying levels in the kidney, muscle, cartilage, brain, lung, ovary and heart (3-5). The functions of CCN3 protein among these different tissues are, however, different. CCN3 was originally described as antiproliferative (3), and its expression was associated with differentiation of Wilms' tumor (4), rhabdomyosarcomas (6), neuroblastomas (7), cartilaginous tumors (8), adrenocortical tumors (9) and with inhibition of the growth and decrease in tumorigenicity of several tumor cell lines including glioblastoma (10), choriocarcinoma (11) and Ewing's sarcoma (12). Furthermore, CCN3 expression was correlated with the increased proliferative index of 3T3 fibroblast (13) and tissue samples of the prostate (14). Although CCN3 reduced the growth rate of Ewing's sarcoma transfectants ex vivo, CCN3 expression was associated with poor prognosis and shown to increase cell motility, resulting in enhanced metastatic potential ...