1464

CSPG4

chondroitin sulfate proteoglycan 4;CSPG4;chondroitin sulfate proteoglycan 4

chondroitin sulfate proteoglycan 4 (melanoma-associated)|chondroitin sulfate proteoglycan NG2|melanoma chondroitin sulfate proteoglycan|melanoma-associated chondroitin sulfate proteoglycan

15q24.2

protein-coding

INTRODUCTION: We have previously demonstrated that chondroitin sulfate glycosaminoglycans (CS-GAGs) on breast cancer cells function as P-selectin ligands. This study was performed to identify the carrier proteoglycan (PG) and the sulfotransferase gene involved in synthesis of the surface P-selectin-reactive CS-GAGs in human breast cancer cells with high metastatic capacity, as well as to determine a direct role for CS-GAGs in metastatic spread. METHODS: Quantitative real-time PCR (qRT-PCR) and flow cytometry assays were used to detect the expression of genes involved in the sulfation and presentation of chondroitin in several human breast cancer cell lines. Transient transfection of the human breast cancer cell line MDA-MB-231 with the siRNAs for carbohydrate (chondroitin 4) sulfotransferase-11 (CHST11) and chondroitin sulfate proteoglycan 4 (CSPG4 ) was used to investigate the involvement of these genes in expression of surface P-selectin ligands. The expression of CSPG4 and CHST11 in 15 primary invasive breast cancer clinical specimens was assessed by qRT-PCR. The role of CS-GAGs in metastasis was tested using the 4T1 murine mammary cell line (10 mice per group). RESULTS: The CHST11 gene was highly expressed in aggressive breast cancer cells but significantly less so in less aggressive breast cancer cell lines. A positive correlation was observed between the expression levels of CHST11 and P-selectin binding to cells (P < 0.0001). Blocking the expression of CHST11 with siRNA inhibited CS-A expression and P-selectin binding to MDA-MB-231 cells. The carrier proteoglycan CSPG4 was highly expressed on the aggressive breast cancer cell lines and contributed to the P-selectin binding and CS-A expression. In addition, CSPG4 and CHST11 were over-expressed in tumor-containing clinical tissue specimens compared with normal tissues. Enzymatic removal of tumor-cell surface CS-GAGs significantly inhibited lung colonization of the 4T1 murine mammary cell line (P = 0.0002). CONCLUSIONS: Cell surface P-selectin binding depends on CHST11 gene expression. CSPG4 serves as a P-selectin ligand through its CS chain and participates in P-selectin binding to the highly metastatic breast cancer cells. Removal of CS-GAGs greatly reduces metastatic lung colonization by 4T1 cells. The data strongly indicate that CS-GAGs and their biosynthetic pathways are promising targets for the development of anti-metastatic therapies.

Enhanced expression levels of NG2 proteoglycan in presurgical original lesions of soft-tissue sarcoma (STS) patients defines with 55% probability the immediate (i.e., within 12 months postsurgery) risk in these individuals to develop postsurgical secondary lesions, independently of any other clinical trait. It, therefore, provides a molecular factor that alone prospects a particularly unfavorable clinical outcome in such patients. Evaluation of the timing of metastasis formation in patients with high and low levels of NG2 in their primitive lesions further stratified the patients in subsets with diverse lag phases in the occurrence of metastatic disease. In our cohort of high-grade STS cases, transcription of NG2 also showed a 81-fold amplification in metastatic lesions, when compared to primitive ones, and this gene overexpression was accompanied by an abundant but nonuniform in situ expression of its product. In a similar manner as seen in primitive lesions, patients with higher levels of metastatic NG2 encountered a significantly more dismal clinical course. Multivariate analysis asserted that in these individuals upregulation of NG2 represented an absolute independent prognostic parameter. Therefore, minimally invasive assessment of the transcription levels of the NG2 gene represents a parameter capable of predicting the arising of metastatic disease within a definite postsurgery time interval, and affords in adjunct in the definition of life expectance in STS patients.