Varnava, A. | bioRxiv Science

bioRxiv2024

The long non-coding RNA FAM30A regulates the Musashi2-RUNX1 axis and is required for LSC function in AML cells

High expression of the long non-coding RNA (lncRNA) FAM30A has been previously associated with leukemic stem cell (LSC) activity and poor prognosis in both adult and paediatric acute myeloid leukaemia (AML) patients, yet it has not been functionally studied. This study provides the first cellular characterization of FAM30A focussing on an internal tandemly organised region, referred to as FAM30A repeats. FAM30A levels correlated with canonical AML LSC signatures and FAM30A depletion decreased cell viability as well as increased sensitivity to chemotherapeutics. It also inhibited colony formation, promoted granulocytic differentiation and abrogated leukemic engraftment in murine bone marrow in vivo. Overexpression of FAM30A repeats in this setting enhanced stemness, proliferation, chemoresistance, and engraftment thus highlighting the biological relevance of this region for LSC biology. On the molecular level, FAM30A repeats interact with the pro-LSC regulator Musashi-2 (MSI2), positively influencing expression of its targets including RUNX1 isoforms. We herein uncover that this FAM30A-MSI2-RUNX1 regulatory loop is of potential relevance for LSC maintenance in AML. These findings provide valuable insights into FAM30As cellular role and highlight its targeting potential for eliminating LSCs and improving treatment outcomes in AML patients.

cancer biology↗

bioRxiv2024

The Discovery of Small Molecule Inhibitors of cFLIP that Sensitise Tumour Cells to TRAIL

The TNF-related apoptosis-inducing ligand (TRAIL) has potential as a therapeutic agent as it has previously been shown to induce apoptosis in triple-negative breast cancer. Recombinant human TRAIL has shown promise in pre-clinical studies of breast cancer. TRAIL exhibits specificity for triple-negative and treatment-resistant disease subsets. However, several studies have demonstrated that patient tumours exhibit resistance to TRAIL and TRAIL-receptor agonists. We have previously demonstrated that suppression of the TRAIL-receptor inhibitor cFLIP can sensitise breast cancer stem cells to apoptosis inducers, but development of pharmacological inhibitors of cFLIP have been impeded by concerns over structural similarities between cFLIP and the pro-apoptotic procaspase-8. We used molecular dynamics to model the interactions between cFLIP, procaspase-8 and the TRAIL-receptor Death Inducing Signalling Complex (TRAIL-DISC), followed by virtual pharmacophore screening and in-cell viability assays to identify a small-molecule (OH14, 3) that selectively inhibited cFLIP binding to the DISC and promoted TRAIL-mediated apoptosis in breast cancer cell lines. When used in combination with TRAIL, OH14 significantly impaired breast cancer cell viability in primary derived and established cell culture. Given the relatively low (micromolar) potency of the initial hit compound inhibitor OH14 (3), limiting its utility as a preclinical development candidate, we carried out structure-activity relationship studies to find a cFLIP inhibitor with more potent cellular activity. Our findings confirm the proof-of-principle that selective pharmacological inhibition of cFLIP can be used to target a vulnerability in breast cancer cells.

cancer biology↗