Epigenetics: methylation‐associated repression of heparan sulfate 3‐O‐sulfotransferase gene expression contributes to the invasive phenotype of H‐EMC‐SS chondrosarcoma cells

Abstract

Heparan sulfate proteoglycans (HSPGs), strategically located at the cell-tissue-organ interface, regulate major biological processes, including cell proliferation, migration, and adhesion. These vital functions are compromised in tumors, due, in part, to alterations in heparan sulfate (HS) expression and structure. How these modifications occur is largely unknown. Here, we investigated whether epigenetic abnormalities involving aberrant DNA methylation affect HS biosynthetic enzymes in cancer cells. Analysis of the methylation status of glycosyltransferase and sulfotransferase genes in H-HEMC-SS chondrosarcoma cells showed a typical hypermethylation profile of 3-OST sulfotransferase genes. Exposure of chondrosarcoma cells to 5-aza-2'-deoxycytidine (5-Aza-dc), a DNA-methyltransferase inhibitor, up-regulated expression of 3-OST1, 3-OST2, and 3-OST3A mRNAs, indicating that aberrant methylation affects transcription of these genes. Furthermore, HS expression was restored on 5-Aza-dc treatment or reintroduction of 3-OST expression, as shown by indirect immunofluorescence microscopy and/or analysis of HS chains by anion-exchange and gel-filtration chromatography. Notably, 5-Aza-dc treatment of HEMC cells or expression of 3-OST3A cDNA reduced their proliferative and invading properties and augmented adhesion of chondrosarcoma cells. These results provide the first evidence for specific epigenetic regulation of 3-OST genes resulting in altered HSPG sulfation and point to a defect of HS-3-O-sulfation as a factor in cancer progression.

The heparan sulfate sulfotransferase 3-OST3A (HS3ST3A) is a novel tumor regulator and a prognostic marker in breast cancer

“…11,15,31 Our study shows that 3-OST3A was repressed and subjected to hypermethylation in all breast cancer cell lines tested except in HER2+-SKBR3 cells in which, consistently, it was expressed at relatively high level. Further analysis of the chromatin interactors at the 3-OST3A promoter showed that the epigenetic regulation not only depends upon DNA methylation, but also on repressive histone marks, and involves the recruitment of PcG proteins.…”

“…Prompted by studies from us and others pointing to an epigenetic control of 3-OST genes 11,15 , we determined whether 3-OST3A was regulated epigenetically in breast cancer cells. 3 DNA methylation analysis of the 3-OST3A promoter CpG island ( Figure S1A) showed strong hypermethylation in T-47D and MDA-derived cells, while in MCF-7 cells, hypermethylation only occurred downstream from the TSS ( Figure 1B).…”

“…13,14 We recently showed that epigenetic repression of 3-OST genes in chondrosarcoma cells leads to altered HSPG sulfation, and demonstrated tumor-suppressive properties of 3-O-sulfation in chondrosarcoma cells. 15 Identification of the molecular mechanisms underlying the role of HS-modifying enzymes in breast cancer may open new windows for the design of personalized therapies to overcome drug failure and for the discovery of new biomarkers. Here, we demonstrate a critical role of 3-OST3A in specific breast cancer subtypes.…”

Aberrant DNA Methylations in Chondrosarcoma

“…DNA hypermethylation contributes to the development of CS via various cell pathways, including cell cycle, apoptosis, cell adherence and cell-to-cell interaction [25][26][27][28]. For example, P16 INK4a , a well-known tumor suppressor gene, was found to be hypermethylated in the promoter region in CS [26].…”

“…Furthermore, gene silencing induced by DNA hypermethylation is involved in cell-to-cell interaction in CS. Heparan sulfate (HS) proteoglycan is a core protein linked by long linear glycosaminoglycan HS located on the surface of almost every animal cell, and interacts with numerous biological molecules, such as growth factors and cytokines [28,30]. Thereby, HS proteoglycans regulate a number of biological processes, including cell proliferation, migration and adhesion.…”