Electrospun fibrous bio-nanocomposite scaffolds reinforced with cellulose nanocrystals (CNCs) were fabricated by using maleic anhydride (MAH) grafted poly(lactic acid) (PLA) as matrix with improved interfacial adhesion between the two components. Morphological, thermal, mechanical, and in vitro degradation properties as well as basic cytocompatibility using human adult adipose derived mesenchymal stem cells (hASCs) of MAH grafted PLA/CNC (i.e., MPLA/CNC) scaffolds were characterized. Morphological investigation indicated that the diameter and polydispersity of electrospun MPLA/CNC nanofibers were reduced with the increased CNC content. The addition of CNCs improved both the thermal stability and mechanical properties of MPLA/CNC composites. The MPLA/CNC scaffolds at the 5 wt % CNC loading level showed not only superior tensile strength (more than 10 MPa), but also improved stability during in vitro degradation compared with the MPLA and PLA/CNC counterparts. Moreover, the fibrous MPLA/CNC composite scaffolds were non-toxic to hASCs and capable of supporting cell proliferation. This study demonstrates that fibrous MPLA/CNC bio-nanocomposite scaffolds are biodegradable, cytocompatible, and possess useful mechanical properties for bone tissue engineering.
Rationale:
Peritoneal metastasis predicts poor prognosis of gastric cancer (GC) patients, and the underlying mechanisms are poorly understood.
Methods:
The 2-DIGE, MALDI-TOF/TOF MS and single-cell transcriptome were used to detect differentially expressed proteins among normal gastric mucosa, primary GC and peritoneal metastatic tissues. Lentiviruses carrying shRNA and transcription activator-like effector nuclease technology were used to knock down myosin heavy chain 9 (MYH9) expression in GC cell lines. Immunofluorescence, immune transmission electron microscopy, chromatin fractionation, co-immunoprecipitation, and assays for chromatin immunoprecipitation, dual luciferase reporter, agarose-oligonucleotide pull-down, flow cytometry and cell anoikis were performed to uncover nuclear MYH9-induced β-catenin (
CTNNB1
) transcription
in vitro
. Nude mice and conditional transgenic mice were used to investigate the findings
in vivo
.
Results:
We observed that MYH9 was upregulated in metastatic GC tissues and was associated with a poor prognosis of GC patients. Mechanistically, we confirmed that MYH9 was mainly localized in the GC cell nuclei by four potential nuclear localization signals. Nuclear MYH9 bound to the
CTNNB1
promoter through its DNA-binding domain, and interacted with myosin light chain 9, β-actin and RNA polymerase II to promote
CTNNB1
transcription, which conferred resistance to anoikis in GC cells
in vitro
and
in vivo
. Staurosporine reduced nuclear MYH9 S1943 phosphorylation to inhibit
CTNNB1
transcription, Wnt/β-catenin signaling activation and GC progression in both orthotropic xenograft GC nude mouse and transgenic GC mouse models.
Conclusion:
This study identified that nuclear MYH9-induced CTNNB1 expression promotes GC metastasis, which could be inhibited by staurosporine, indicating a novel therapy for GC peritoneal metastasis.
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