PO-259 Inhibition of the hexosamine biosynthetic pathway by targeting PGM3 causes breast cancer growth arrest and apoptosis

Introduction Cancer aberrant N - and O -linked protein glycosylation, frequently resulting from an augmented flux through the Hexosamine Biosynthetic Pathway (HBP), play different roles in tumour progression. Recent studies reported an association between the tumorigenic potential, metastasis and chemoresistance of several type of breast cancer cells and tumours, among which the Triple Negative Breast Cancer (TNBC), and the alteration of their membrane glycans composition and ramification as well as of their level of protein O -Glc N Ac. However, the low specificity and toxicity of the existing HBP inhibitors prevented their use for cancer treatment. Material and methods In order to identify a novel inhibitor of HBP pathway and in particular of the PGM3 enzyme, we performed a virtual screening by using computational approaches. These approaches lead us to the identification of a lead compound. This compound, named FR054, has been synthetized and in vitro and in vivo tested by using several biophysical methods (NMR, LC/MS, HPLC) and biochemical assay (CETSA, ITDRF, FACS analysis) as well as tested in TNBC xenograft mice model. Results and discussions Here we report the preclinical evaluation of FR054, a novel inhibitor of the HBP enzyme PGM3, with a remarkable anti-breast cancer effect. In fact, FR054 induces in different breast cancer cells a dramatic decrease in cell proliferation and survival. In particular, in a model of Triple Negative Breast Cancer (TNBC) cells, MDA-MB-231, we show that these effects are correlated to FR054-dependent reduction of both N - and O -glycosylation level that cause also to a strong reduction of cancer cell adhesion and migration. Moreover we show that impaired survival of cancer cells upon FR054 treatment is associated with activation of the Unfolded Protein Response (UPR) and accumulation of intracellular ROS. Finally, we show that FR054 suppresses cancer growth in MDA-MB-231 xenograft mice. Conclusion Our data support the advantage of targeting HBP for therapeutic purpose and encourage further investigation about the use of this small-molecule as promising compound for breast cancer therapy.