Glypican-3 expression is silenced in human breast cancer

Glypican-3 is overexpressed in human hepatocellular carcinoma

To identify candidate genes that could be used as diagnostic and therapeutic targets for hepatocellular carcinoma (HCC), we searched for the genes that are overexpressed in HCC by combining representational difference analysis and microarray. Genes such as glypican-3 (GPC3), insulin-like growth factor 2, long-chain fatty-acid-coenzyme A ligase 4, farnesyl diphosphate synthase were frequently identified in our screening. Northern blot analysis with these four genes confirmed their overexpression in HCC. Among them we found that GPC3 transcript is upregulated in six out of seven cases of HCC. Immunoblot and immunohistochemical staining using polyclonal anti-GPC3 antibodies further confirmed that GPC3 protein is indeed increased in HCC tumor samples. We also found that GPC3 is secreted into culture media from cell lines derived from HCC. We conclude that GPC3 is a good molecular marker for HCC.

Genotype/phenotype correlations of males affected by Simpson-Golabi-Behmel syndrome with GPC3 gene mutations: patient report and review of the literature

Simpson-Golabi-Behmel syndrome (SGBS) is an X-linked overgrowth syndrome with associated visceral and skeletal anomalies. Deletions or point mutations involving the glypican-3 (GPC3) gene at Xq26 are associated with a relatively milder form of this disorder (SGBS1). GPC3 encodes a putative extracellular proteoglycan, glypican-3, that is inferred to play an important role in growth control in embryonic mesodermal tissues in which it is selectively expressed. It appears to form a complex with insulin-like growth factor-II (IGF-II), and might thereby modulate IGF-II action. We reviewed the clinical findings of all published patients with SGBS1 with GPC3 mutations to confirm the clinical specificity for the SGBS1 phenotype. Moreover, we report on a new patient with a GPC3 deletion and IGF-II evaluation.

Gene Expression Profiling of Renal Cell Carcinoma and Its Implications in Diagnosis, Prognosis, and Therapeutics

Renal cell carcinoma (RCC) is the 10th most common cancer in the United States. It is a histologically heterogeneous disease with various histologic types being characterized by distinct genetic alterations. This chapter reviews advances in the gene expression profiling of RCC and discusses their clinical implications. Data are promising, and many more RCC-related microarray studies are currently underway or in planning. Undoubtedly these data will have an impact on the diagnosis, prognosis, and treatment of RCCs in the future. Finally, this chapter discusses what additional studies should be performed to help uncover the molecular mechanisms of RCC and to bring this new knowledge into use in the clinical arena.

A novel repeat in the melanoma-associated chondroitin sulfate proteoglycan defines a new protein family

The human melanoma-associated chondroitin sulfate proteoglycan (MCSP) and its rat ortholog NG2 are thought to play important roles in angiogenesis-dependent processes like wound healing and tumor growth. Based on electron microscopy studies, the highly glycosylated ectodomain of NG2 has been subdivided into the globular N-terminus, a flexible rod-like central region and a C-terminal portion in globular conformation. We identified a novel repeat named CSPG in the central ectodomain of NG2, MCSP and other proteins from fly, worm, human, sea urchin and a cyanobacterium which shows similarity to cadherin repeats. As earlier electron microscopy studies indicate, the folding of the tandem repeats compresses the length of the proposed repeat region by a factor of approximately 10 compared to the fully extended peptide chain. We identified two conserved negatively charged residues which might govern the binding properties of CSPG repeats. The phyletic distribution of CSPG repeats suggests that horizontal gene transfer contributed to their evolutionary history.

DNA methylation and breast carcinogenesis

Knowledge about breast carcinogenesis has accumulated during the last decades but has barely been translated into strategies for early detection or prevention of this common disease. Changes in DNA methylation have been recognized as one of the most common molecular alterations in human neoplasia and hypermethylation of gene-promoter regions is being revealed as one of the most frequent mechanisms of loss of gene function. The heritability of methylation states and the secondary nature of the decision to attract or exclude methylation support the idea that DNA methylation is adapted for a specific cellular memory. According to Hanahan and Weinberg, there are six novel capabilities a cell has to acquire to become a cancer cell: limitless replicative potential, self-sufficiency in growth signals, insensitivity to growth-inhibitory signals, evasion of programmed cell death, sustained angiogenesis and tissue invasion and metastasis. This review highlights how DNA-methylation contributes to these features and offers suggestions about how these changes could be prevented, reverted or used as a 'tag' for early detection of breast cancer or, preferably, for detection of premalignant changes.

Proteoglycans and tumor progression: Janus-faced molecules with contradictory functions in cancer

Understanding the details of the molecular mechanism of tumor dissemination revealed that several proteoglycan species are involved in the process but their role can be described as Janus-faced. One level of proteoglycan alterations is at the expression of their genes coding for the core protein. Characteristically, in progressing tumors two patterns emerged: loss or neoexpression of surface proteoglycans (PG) depending on the initial expression pattern of the cell type of origin. The situation is similarly complex concerning the changes of glycosaminoglycan (GAG) of the PG during tumor progression. This is due to the fact that the majority of PGs involved is hybrid molecule meaning that their core protein can be glycanated both with chondroitin and heparan sulfate. However, such an alteration in glycanation of PG may fundamentally change the function of the molecule, especially the one operating at the cell surface. Among the extracellular PGs, decorin emerged as inhibitor of progression while perlecan as a promoter of the process. Analysis of the available data indicate that during metastatization tumor cells must express at least one cell surface HSPG species from the syndecan-glypican-CD44v3 group. Furthermore, the HS-chain of these proteoglycan(s) carry important molecular signatures (suphution or epimerization patterns). Experimental data suggest that tumor cell surface heparan sulfate (PG) may provide a target for specific anti-metastatic interventions.