Addiction of Merkel cell carcinoma to MUC1-C identifies a potential new target for treatment

Abstract

Merkel cell carcinoma (MCC) is an aggressive malignancy with neuroendocrine (NE) features, limited treatment options, and a lack of druggable targets. There is no reported involvement of the MUC1-C oncogenic protein in MCC progression. We show here that MUC1-C is broadly expressed in MCCs and at higher levels in Merkel cell polyomavirus (MCPyV)-positive (MCCP) relative to MCPyV-negative (MCCN) tumors. Our results further demonstrate that MUC1-C is expressed in MCCP, as well as MCCN, cell lines and regulates common sets of signaling pathways related to RNA synthesis, processing, and transport in both subtypes. Mechanistically, MUC1-C (i) interacts with MYCL, which drives MCC progression, (ii) is necessary for expression of the OCT4, SOX2, KLF4, MYC, and NANOG pluripotency factors, and (iii) induces the NEUROD1, BRN2 and ATOH1 NE lineage dictating transcription factors. We show that MUC1-C is also necessary for MCCP and MCCN cell survival by suppressing DNA replication stress, the p53 pathway, and apoptosis. In concert with these results, targeting MUC1-C genetically and pharmacologically inhibits MCC self-renewal capacity and tumorigenicity. These findings demonstrate that MCCP and MCCN cells are addicted to MUC1-C and identify MUC1-C as a potential target for MCC treatment.

Neurogenin 2 and Neuronal Differentiation 1 control proper development of the chick trigeminal ganglion and its nerve branches

“…Upon electroporation with NeuroD1 and control MOs, immunoblotting for NeuroD1 protein revealed three distinct bands (Figure 4). NeuroD1 protein has a predicted molecular weight of approximately 39 kDa in chick (Uniprot); however, immunoblot data has shown bands of various molecular weights (e.g., antibody websites), with a predominant band at 50 kDa [26–30]. Given that all three bands showed a reduction after knockdown, we conclude that all three bands represent NeuroD1 protein.…”

“…Moreover, axon growth is regulated by guidance molecules, adhesion proteins, and neurotrophic factors [34]. The aberrant innervation of the eye that we observe after Neurog2 and NeuroD1 knockdown (Figures 2, 3, 6) could point to dysregulation of genes involved in these processes, such as those encoding neurotrophin receptors and/or neurotrophins, since lack of neurotrophic support leads to target innervation defects and neuronal cell death [29, 30]. Alternatively, it is possible that ophthalmic branch axons reach their target tissues normally after Neurog2 or NeuroD1 depletion, but are then retracted due to compromised cytoskeletal modifications caused by Neurog2 and/or NeuroD1 knockdown, as discussed above, which could be examined in the chick system in future experiments.…”

MUC1-C is a master regulator of MICA/B NKG2D ligand and exosome secretion in human cancer cells

“…MUC1shRNA (MISSION shRNA TRCN0000122938; Sigma) was inserted into the pLKO-tet-puro vector (Plasmid #21915; Addgene, Cambridge, Massachusetts, USA) as described. 24 The MUC1shRNA#2 (MISSION shRNA TRCN0000430218) and NF-κBshRNA (MISSION shRNA TRCN0000014687) were produced in HEK293T cells as described. 25 pIRESpuro2 vector and pIRESpuro2-MUC1 were generated as described 26 and transfected into HCT116 cells with Lipofectamine.…”

“…The cDNA samples were amplified using the Power SYBR Green PCR Master Mix (Applied Biosystems) and the CFX96 Real-Time PCR System (BIO-RAD, Hercules, CA, USA) as described. 24 Primers used for qRT-PCR are listed in online supplemental table S1 .…”

“…Cells (3000) were seeded per well in 6-well ultra-low attachment culture plates (Corning Life Sciences) in DMEM/F12 50/50 medium (Corning Life Sciences) with 20 ng/mL EGF (Millipore Sigma), 20 ng/mL bFGF (Millipore Sigma) and 1% B27 supplement (Gibco) as described. 24 …”