RESUMO
Background: Glycosylation is one of the most fundamental post-translational modifications. Importantly, glycosylation is altered in many cancers. These alterations have been proven to impact on tumor progression and to promote tumor cell survival. From the literature, it is known that there is a clear link between chemoresistance and hypoxia, hypoxia and epigenetics and more recently glycosylation and epigenetics. Methods and Results: Our objective was to investigate these differential parameters, in an in vitro model of ovarian and breast cancer. Ovarian (A2780, A2780cis, PEO1, PEO4) and triple negative breast cancer (TNBC) (MDA-MB-231 and MDA-MB-436) cells were exposed to differential hypoxic conditions (0.5-2% O2) and compared to normoxia (21% O2). Results demonstrated that in hypoxic conditions some significant changes in glycosylation on the secreted N-glycans from the ovarian and breast cancer cell lines were observed. These included, alterations in oligomannosylated, bisected glycans, glycans with polylactosamine extensions, in branching, galactosylation and sialylation in all cell lines except for PEO1. In general, hypoxia exposed ovarian and TNBC cells also displayed increased epithelial to mesenchymal transition (EMT) and migration, with a greater effect seen in the 0.5% hypoxia exposed samples compared to 1 and 2% hypoxia (p ≤ 0.05). SiRNA transient knock down of GATA2/3 transcription factors resulted in a decrease in the expression of glycosyltransferases ST3GAL4 and MGAT5, which are responsible for sialylation and branching, respectively. Conclusions: These glycan changes are known to be integral to cancer cell survival and metastases, suggesting a possible mechanism of action, linking GATA2 and 3, and invasiveness of both ovarian and TNBC cells in vitro.
RESUMO
The injectable hydrogel with desirable biocompatibility and tunable properties can improve the efficacy of stem cell-based therapy. However, the development of injectable hydrogel remains a great challenge due to the restriction of crosslinking efficiency, mechanical properties, and potential toxicity. Here, we report that a new injectable hydrogel system was fabricated from hyperbranched multi-acrylated poly(ethylene glycol) macromers (HP-PEGs) and thiolated hyaluronic acid (HA-SH) and used as a stem cell delivery and retention platform. The new HP-PEGs were synthesized via in situ reversible addition fragmentation chain transfer (RAFT) polymerization using an FDA approved anti-alcoholic drug-Disulfiram (DS) as the RAFT agent precursor. HP-PEGs can form injectable hydrogels with HA-SH rapidly via thiol-ene click reaction under physiological conditions. The hydrogels exhibited stable mechanical properties, non-swelling and anti-fouling properties. Hydrogels encapsulating adipose-derived stem cells (ADSCs) have demonstrated promising regenerative capabilities such as the maintenance of ADSCs' stemness and secretion abilities. The ADSCs embedded hydrogels were tested on the treatment of diabetic wound in a diabetic murine animal model, showing enhanced wound healing. STATEMENT OF SIGNIFICANCE: Diabetic wounds, which are a severe type of diabetes, have become one of the most serious clinical problems. There is a great promise in the delivery of adipose stem cells into wound sites using injectable hydrogels that can improve diabetic wound healing. Due to the biocompatibility of poly(ethylene glycol) diacrylate (PEGDA), we developed an in situ RAFT polymerization approach using anti-alcoholic drug-Disulfiram (DS) as a RAFT agent precursor to achieve hyperbranched PEGDA (HP-PEG). HP-PEG can form an injectable hydrogel by crosslinking with thiolated hyaluronic acid (HA-SH). ADSCs can maintain their regenerative ability and be delivered into the wound sites. Hence, diabetic wound healing process was remarkably promoted, including inhibition of inflammation, enhanced angiogenesis and re-epithelialization. Taken together, the ADSCs-seeded injectable hydrogel may be a promising candidate for diabetic wound treatment.