3485

IGFBP2

insulin-like growth factor binding protein 2, 36kDa;IGFBP2;insulin-like growth factor binding protein 2, 36kDa

IBP-2|IGF-binding protein 2|IGFBP-2|insulin-like growth factor-binding protein 2

2q35

protein-coding

Overexpression of insulin-like growth factor binding protein-2 (IGFBP-2) has been shown to be associated with tumor progression in several human malignant tumors; however, the significance of IGFBP-2 expression in bladder cancer remains poorly defined. The objective of this study was to investigate the effect of IGFBP-2 overexpression in human bladder cancer KoTCC-1 cells on their phenotype associated with tumor progression. We introduced IGFBP-2 cDNA into KoTCC-1 cells, which do not express a detectable level of IGFBP-2 protein, thus generating an IGFBP-2 overexpressing cell line (KoTCC-1/BP2). We also generated a vector-only-transfected cell line (KoTCC-1/C) as a control. Despite the absence of a significant difference in in vitro cell growth rates and motilities among KoTCC-1 sublines, KoTCC-1/BP2 exhibited significantly higher invasive ability than KoTCC-1/C. Gelatin zymography showed a marked increase in matrix metalloproteinase-2 (MMP-2) production by KoTCC-1/BP2 compared with that by KoTCC-1/C. Furthermore, there was no significant difference in sub-cutaneous tumor growth among KoTCC-1 sublines; however, more advanced tumor progression, including lymph node metastasis and hemorrhagic ascites formation, was observed after the implantation of KoTCC-1/BP2 into the bladder wall of nude mice than after the implantation of KoTCC-1/C. These findings suggest that overexpression of IGFBP-2 induces an increase in MMP-2 production, resulting in the enhanced metastatic potential of bladder cancer.

The family of insulin-like growth factor binding proteins (IGFBPs) comprises six members which bind and regulate the functions of IGFs. Overexpression of IGFBP2 and IGFBP5 contributes to the invasiveness and progression of several human cancers, but their roles in the metastasis of breast cancer have not been investigated in detail. To determine their roles, we examined IGFBP2 and IGFBP5 expression levels in 164 T1 breast carcinomas using tissue microarrays and immunohistochemistry. The specimens were divided into those with (N1) or without (N0) axillary lymph node involvement. The results were associated with clinicopathologic parameters and prognostic molecular markers. No or very low expression of IGFBP2 and IGFBP5 was detected in normal breast epithelium or benign breast tissue with fibrocystic change. Moderate to strong cytoplasmic staining for IGFBP2 and IGFBP5 was detected in 49.1% and 50.3% of T1 invasive breast carcinomas, respectively. T1N1 carcinomas were more frequent to have moderate and strong-positive staining for IGFBP2 and IGFBP5 than in T1N0 carcinomas (p < 0.05). IGFBP2 and IGFBP5 expression correlated with the expression status of progesterone receptor and HER-2/neu in the overall T1 carcinoma group, but no association was found with tumor size or the expression status of estrogen receptor. Our data suggest that IGFBP2 and IGFBP5 play a role in the development of metastasis and may serve as useful markers to predict lymph node metastasis in patients with small (T1) invasive breast carcinomas.

BACKGROUND: Insulin like growth factor binding proteins modulate the mitogenic and pro survival effects of IGF. Elevated expression of IGFBP2 is associated with progression of tumors that include prostate, ovarian, glioma among others. Though implicated in the progression of breast cancer, the molecular mechanisms involved in IGFBP2 actions are not well defined. This study investigates the molecular targets and biological pathways targeted by IGFBP2 in breast cancer. METHODS: Transcriptome analysis of breast tumor cells (BT474) with stable knockdown of IGFBP2 and breast tumors having differential expression of IGFBP2 by immunohistochemistry was performed using microarray. Differential gene expression was established using R-Bioconductor package. For validation, gene expression was determined by qPCR. Inhibitors of IGF1R and integrin pathway were utilized to study the mechanism of regulation of beta-catenin. Immunohistochemical and immunocytochemical staining was performed on breast tumors and experimental cells, respectively for beta-catenin and IGFBP2 expression. RESULTS: Knockdown of IGFBP2 resulted in differential expression of 2067 up regulated and 2002 down regulated genes in breast cancer cells. Down regulated genes principally belong to cell cycle, DNA replication, repair, p53 signaling, oxidative phosphorylation, Wnt signaling. Whole genome expression analysis of breast tumors with or without IGFBP2 expression indicated changes in genes belonging to Focal adhesion, Map kinase and Wnt signaling pathways. Interestingly, IGFBP2 knockdown clones showed reduced expression of beta- catenin compared to control cells which was restored upon IGFBP2 re-expression. The regulation of beta-catenin by IGFBP2 was found to be IGF1R and integrin pathway dependent. Furthermore, IGFBP2 and beta-catenin are co-ordinately overexpressed in breast tumors and correlate with lymph node metastasis. CONCLUSION: This study highlights regulation of beta-catenin by IGFBP2 in breast cancer cells and most importantly, combined expression of IGFBP2 and beta-catenin is associated with lymph node metastasis of breast tumors.

Insulin-like growth factor binding protein 2 (IGFBP2) is involved in the progression of many epithelial cancers. However, its role in non-small cell lung cancer (NSCLC), another type of epithelial cancer, remains unclear. We detected IGFBP2 expression using immunohistochemistry in surgically resected tumors from 110 NSCLC patients, 37 of which had metastases. The positive rate of IGFBP2 expression was compared between the metastatic and the non-metastatic group, and correlations of IGFBP2 expression with metastasis and overall survival were analyzed. We also investigated the expression of IGFBP2 in microvesicles (MVs) collected from primary lung cancer cell cultures, and in different locations of newly resected NSCLC tumors, using immunoblotting. The overall positive rate of IGFBP2 expression in lung cancer was 51.8 % and it was significantly higher in the metastatic group than in the non-metastatic group (70.3 and 42.5 % respectively, p < 0.01). And the higher the lymph node stage, the higher the positive rate. Cytoplasmic expression was predominant in the majority of the tumors. Based on multivariate regression analysis, IGFBP2 was correlated with metastasis and poor overall survival (Hazard ratio: 3.56 and 3.23 respectively). IGFBP2 was detectable in the MVs collected from IGFBP2 positive cell lines, and its expression was most abundant in the marginal region of the newly resected tumors. IGFBP2 is associated with metastasis and poor survival of lung cancer. Its presence in MVs and high abundance in the marginal region of tumors suggest that its association with metastasis may be related to tumor microenviroment remodeling in NSCLC.

BACKGROUND: Insulin-like growth factor-1 (IGF-1) is one of the most critical proteins required for the survival, migration, and growth of melanoma cells. IGF-binding protein 2 (IGFBP2), which binds and regulates the function of IGF-1, is upregulated in a dose-dependent manner in melanoma cells treated with IGF-1, suggesting a possible role of IGFBP2 in the pathogenesis of melanoma. METHODS: Tissue microarrays were constructed using formalin-fixed, paraffin-embedded archival tissue blocks from 94 melanocytic lesions: 20 benign nevi, 20 dysplastic nevi, 23 primary melanomas, and 31 metastatic melanomas. IGFBP2 expression was evaluated immunohistochemically using a polyclonal antibody against the C-terminus of IGFBP2. The number of cells and labeling intensity were assessed semiquantitatively. RESULTS: Positive IGFBP2 labeling was observed in 5.0% of benign nevi, which was significantly lower than in dysplastic nevi (35.0%), primary melanomas (52.2%), or metastatic melanomas (54.8%) (p < 0.05). Among the IGFBP2-positive cases, moderate-to-strong immunostaining was observed in 64.7% of metastatic melanomas and 33.3% of primary melanomas. But none of the dysplastic nevi had moderate-to-strong immunostaining (p < 0.05). CONCLUSIONS: Our study shows that IGFBP2 expression increases from benign and dysplastic nevi to primary and metastatic melanomas and suggests that it may play a role in melanoma progression.