Hypoxia and serum deprivation induces glycan alterations in triple negative breast cancer cells

Abstract

Triple negative breast cancer (TNBC) is a major global public health problem. The lack of targeted therapy and the elevated mortality evidence the need for better knowledge of the tumor biology. Hypoxia and aberrant glycosylation are associated with advanced stages of malignancy, tumor progression and treatment resistance. Importantly, serum deprivation regulates the invasive phenotype and favors TNBC cell survival. However, in TNBC, the role of hypoxia and serum deprivation in the regulation of glycosylation remains largely unknown. The effects of hypoxia and serum deprivation on the expression of glycosyltransferases and glycan profile were evaluated in the MDA-MB-231 cell line. We showed that the overexpression of HIF-1α was accompanied by acquisition of epithelial-mesenchimal transition features. Significant upregulation of fucosyl- and sialyltransferases involved in the synthesis of tumor-associated carbohydrate antigens was observed together with changes in fucosylation and sialylation detected by Aleuria aurantia lectin and Sambucus nigra agglutinin lectin blots. Bioinformatic analysis further indicated a mechanism by which HIF-1α can regulate ST3GAL6 expression and the relationship within the intrinsic characteristics of TNBC tumors. In conclusion, our results showed the involvement of hypoxia and serum deprivation in glycosylation profile regulation of TNBC cells triggering breast cancer aggressive features and suggesting glycosylation as a potential diagnostic and therapeutic target.

Identification of appropriate housekeeping genes for quantitative RT-PCR analysis in MDA-MB-231 and NCI-H460 human cancer cell lines under hypoxia and serum deprivation

“…A BINDER C-150 incubator (BINDER GmbH, Tuttlingen, Germany) was used for the hypoxia experiments. The increased expression and the nuclear location of the hypoxia marker HIF-1α validated our hypoxic system [20].…”

“…The transcription analysis was performed after forty-eight hours of incubating the cells under the four different conditions (N10, N0, H10 and H0), since in this interval of time no major changes in cell viability were displayed [20]. Total cellular RNA was extracted using the TRIzol Reagent (Invitrogen, USA) according to manufacturer's instructions.…”

Identification of glycogene-type and validation of ST3GAL6 as a biomarker predicts clinical outcome and cancer cell invasion in urinary bladder cancer

“…ST3GAL6 is reported to be regulated at multiple levels. Under hypoxic or inflammatory conditions, stabilized HIF1α and IL6 or IL8 induced ST3GAL6 at transcriptional level in MDA-MB-231 and human bronchial mucosa cells, respectively 49 . LncRNA ST3GAL6-AS1, overlapping with ST3GAL6 at genomic level, positively regulated its host gene ST3GAL6 by recruiting MLL1 protein to enhance H3K4me3 level at ST3GAL6 promoter region 46 .…”

Glycoproteomics identifies HOMER3 as a potentially targetable biomarker triggered by hypoxia and glucose deprivation in bladder cancer

“…The most striking stems from a drastic stop in protein O-glycosylation (occurring in Serine and/or Threonine residues) extension through sialylation, leading to the biosynthesis of sialylated short-chain O-GalNAc glycans, as sialyl-Tn (STn) and mono−/di-sialylated T antigens (herein termed ST antigens) [12][13][14][15][16][17]. The simplification of cancer cells O-glycome towards accumulation of these glycans has been suggested to be intimately linked to the downregulation of glycosyltransferases that extend glycan chains, as part of the cellular reprogramming necessary to support oxygen shortage (hypoxia) and nutrient deprivation derived from uncontrolled tumour growth and ineffective neovasculature [18][19][20]. Moreover, alterations in glycosylation under hypoxia are concomitant to the acquisition of mesenchymal phenotypes and increased cell invasion [18], suggesting that glycans may play an important role at this level that may be explored to target more aggressive cancer cells.…”