Metabolic glycoengineering sensitizes drug-resistant pancreatic cancer cells to tyrosine kinase inhibitors erlotinib and gefitinib

Abstract

Metastatic human pancreatic cancer cells (the SW1990 line) that are resistant to the EGFR-targeting tyrosine kinase inhibitor drugs (TKI) erlotinib and gefitinib were treated with 1,3,4-O-Bu3ManNAc, a “metabolic glycoengineering” drug candidate that increased sialylation by ∼12-fold. Consistent with genetic methods previously used to increase EGFR sialylation, this small molecule reduced EGF binding, EGFR transphosporylation, and downstream STAT activation. Significantly, co-treatment with both the sugar pharmacophore and the existing TKI drugs resulted in strong synergy, in essence re-sensitizing the SW1990 cells to these drugs. Finally, l,3,4-O-Bu3ManNAz, which is the azido-modified counterpart to l,3,4-O-Bu3ManNAc, provided a similar benefit thereby establishing a broad-based foundation to extend a “metabolic glycoengineering” approach to clinical applications.

Nutrient-deprived cancer cells preferentially use sialic acid to maintain cell surface glycosylation

“…To explore the importance of sialic acid supplementation of nutrient-deprived cells on specific membrane glycoproteins, two cell surface receptors (EGFR and MUC1) were chosen because of their important roles in promoting tumor growth and metastasis, which have previously been investigated in our laboratories [32, 33]. To verify that EGFR and MUC1 were over-expressed, over-sialylated, or both EGFR and MUC1 were immuno-precipitated and analyzed by Western blot analysis using commercial antibodies that recognized the un-glycosylated form of each protein.…”

Metabolic flux-driven sialylation alters internalization, recycling, and drug sensitivity of the epidermal growth factor receptor (EGFR) in SW1990 pancreatic cancer cells

“…The basis for evoking the galectin lattice – as outlined in Figure 4 – to explain the impact of 1,3,4- O -Bu 3 ManNAc in SW1990 cells is that α2,6-sialic acid inhibits galectin affinity for underlying galactose/GalNAc epitopes [48]; the resulting negative regulation of the lattice reduces surface display of EGFR by promoting internalization, which reduces signaling potency [45]. Building on data from earlier experiments, (e.g., our prior publications [1, 4]), Figures 1 and 2 of this paper, and support from modeling simulations (see the Supplemental Material), we showed (e.g., in Figure 5) that increased internalization consistent with attenuation of the galectin lattice occurs.…”

Harnessing cancer cell metabolism for theranostic applications using metabolic glycoengineering of sialic acid in breast cancer as a pioneering example

“…As a counterpoint, there now are indications that the Golgi CMP-sialic acid transporter is “leaky,” allowing import of CMP-sialic acid without the concurrent export of CMP albeit at a slower rate [89]. The “leaky” nature of this transporter is borne out by sialic acid supplementation strategies (as discussed in Section 4.3 below) where increased production of CMP-sialic acid does have an impact on sialylation, increasing cell surface levels of this sugar [43, 90, 91]. …”

“…For example, installation of fluorinated sialic acids into cancer cell glycans was inspired by the hope that these “Teflon-like” moieties would reduce metastasis by making it difficult for cell traveling through the body to re-attach to the ECM and initiate expansion into a secondary tumor [168, 214]. In a second example, we found that increased sialylation achieved by treating cells with the “high flux” analogue 1,3,4- O -Bu 3 ManNAc [82, 83, 215] restored sensitivity of drug-resistant cancer cells to tyrosine kinase inhibitors (TKIs) [90] by altering cell surface receptor trafficking, internalization, and recycling [91]. Finally, efforts are underway to increase the immunogenicity of TACAs by installation of non-natural sialosides such as “Neu5Prop” (which has an elongated N-acyl group) or “Neu5Ph” (which has a phenyl ring attached to the N-acyl group) [216, 217].…”

“…A technical foundation for combining diagnostic and therapeutic modalities into a single nano-sized construct is illustrated by the MGE analogue 1,3,4- O -Bu 3 ManNAc that can be formulated into sebacic acid (SA) – polyethylene glycol (PEG) nanoparticles for controlled release [222] thereby increasing potency for applications such as sensitizing drug resistant cells to TKIs [90, 91]. Similarly, monosaccharide analogues used in MGE can be formulated into biodegradable poly(lactic-co-glycolic acid) (PLGA) constructs for controlled release in vivo [223].…”