Loss of G0/G1 switch gene 2 (G0S2) promotes disease progression and drug resistance in chronic myeloid leukaemia (CML) by disrupting glycerophospholipid metabolism.

Tyrosine kinase inhibitors (TKIs) targeting BCR::ABL1 have turned chronic myeloid leukaemia (CML) from a fatal disease into a manageable condition for most patients. Despite improved survival, targeting drug-resistant leukaemia stem cells (LSCs) remains a challenge for curative CML therapy. Aberrant lipid metabolism can have a large impact on membrane dynamics, cell survival and therapeutic responses in cancer. While ceramide and sphingolipid levels were previously correlated with TKI response in CML, the role of lipid metabolism in TKI resistance is not well understood. We have identified downregulation of a critical regulator of lipid metabolism, G0/G1 switch gene 2 (G0S2), in multiple scenarios of TKI resistance, including (1) BCR::ABL1 kinase-independent TKI resistance, (2) progression of CML from the chronic to the blast phase of the disease, and (3) in CML versus normal myeloid progenitors. Accordingly, CML patients with low G0S2 expression levels had a worse overall survival. G0S2 downregulation in CML was not a result of promoter hypermethylation or BCR::ABL1 kinase activity, but was rather due to transcriptional repression by MYC. Using CML cell lines, patient samples and G0s2 knockout (G0s2-/- ) mice, we demonstrate a tumour suppressor role for G0S2 in CML and TKI resistance. Our data suggest that reduced G0S2 protein expression in CML disrupts glycerophospholipid metabolism, correlating with a block of differentiation that renders CML cells resistant to therapy. Altogether, our data unravel a new role for G0S2 in regulating myeloid differentiation and TKI response in CML, and suggest that restoring G0S2 may have clinical utility.

Detection of Anticancer Drug-Induced Cardiotoxicity Using VCAM1-Targeted Nanoprobes.

Chemotherapy-induced cardiac toxicity is an undesirable yet very common effect that increases the risk of death and reduce the quality of life of individuals undergoing chemotherapy. However, no feasible methods and techniques are available to monitor and detect the degree of cardiotoxicity at an early stage. Therefore, in this project, we aim to develop a fluorescent nanoprobe to image the toxicity within the cardiac tissue induced by an anticancer drug. We have observed that vascular cell adhesion molecule 1 (VCAM1) protein alone with collagen was overly expressed within the heart, when an animal was treated with doxorubicin (DOX), because of inflammation in the epithelial cells. We hypothesize that developing a VCAM1-targeted peptide-based (VHPKQHRGGSKGC) fluorescent nanoprobe can detect and visualize the affected heart. In this regard, we prepared a poly(lactic-co-glycolic acid) (PLGA) nanoparticle linked with VCAM1 peptide and rhodamine B (PLGA-VCAM1-RhB). Selective binding and higher accumulation of the PLGA-VCAM1-RhB nanoprobes were detected in DOX-treated human cardiomyocyte cells (HCMs) compared to the untreated cells. For in vivo studies, DOX (5 mg/kg) was injected via the tail vein once in two weeks for 6 weeks (3 injection total). PLGA-VCAM1-RhB and PLGA-RhB were injected via the tail vein after 1 week of the last dose of DOX, and images were taken 4 h after administration. A higher fluorescent signal of PLGA-RhB-VCAM-1 (48.62% ± 12.79%) was observed in DOX-treated animals compared to the untreated control PLGA-RhB (10.61% ± 4.90) within the heart, indicating the specificity and targeting ability of PLGA-VCAM1-RhB to the inflamed tissues. The quantified fluorescence intensity of the homogenized cardiac tissue of PLGA-RhB-VCAM1 showed 156% higher intensity than the healthy control group. We conclude that PLGA-VCAM1-RhB has the potential to bind inflamed cardiac cells, thereby detecting DOX-induced cardiotoxicity and damaged heart at an early stage.