6360abefb0d6371309cc9857
Abstract
Objective
To
investigate the role of Wnt1 (a key ligand of canonical Wnt pathway) in
colorectal cancer (CRC) cell proliferation, migration, invasion and its
regulatory effect on Wnt signaling.
Methods
Wnt1
expression was detected in CRC cell lines (HCT116, SW480) and normal colonic
epithelial cell line (NCM460) by Western blot and qRT-PCR. Wnt1 was
overexpressed via plasmid (pcDNA3.1-Wnt1) or knocked down via siRNA in HCT116
cells. Cell proliferation (CCK-8), migration (scratch assay), invasion
(Transwell), sphere formation (stemness assay) and canonical Wnt-related
proteins (active β-catenin, Cyclin D1, CD133) were analyzed.
Results
Wnt1 was
upregulated in CRC cells compared with NCM460 (P<0.01), with higher
expression in metastatic SW480. Wnt1 overexpression increased HCT116 cell
proliferation (OD450 at 72h: 1.48±0.14 vs. 0.98±0.10, P<0.05), migration
rate (76.2±6.3% vs. 47.8±4.8%, P<0.01), invasive cell number (145±12 vs.
63±7, P<0.01) and sphere formation efficiency (3.2±0.3 folds vs. control,
P<0.01), while enhancing active β-catenin accumulation, Cyclin D1 and CD133
expression (P<0.05). Wnt1 knockdown showed opposite effects.
Conclusion
Wnt1
promotes CRC progression by activating canonical Wnt/β-Catenin signaling and
regulating stemness/pro-metastatic genes, serving as a potential therapeutic
target.
Keywords: Colorectal Cancer; Cell
Proliferation; Transwell
Introduction
Colorectal
cancer (CRC) is a leading cause of cancer-related mortality globally, with
~935,000 annual deaths1. The canonical Wnt/β-catenin pathway is constitutively activated in
over 85% of CRC cases and its activation is initiated by binding of Wnt ligands
to Frizzled (FZD) receptors and LRP5/6 co-receptors2. Wnt1, one of
the first identified Wnt family members, is a prototypical canonical Wnt ligand-its
physiological role includes embryonic development and tissue regeneration, but
aberrant expression in tumors drives uncontrolled cell cycle progression,
cancer stem cell (CSC) maintenance and epithelial-mesenchymal transition (EMT)3,4. Clinical
studies have shown Wnt1 expression is elevated in CRC tissues, correlating with
tumor grade, lymph node metastasis and reduced 5-year survival5,6. However,
Wnt1’s functional role in CRC cell behaviors (especially cell cycle regulation)
and its mechanism of regulating canonical Wnt/β-catenin activation remain to be
fully clarified. This study uses CRC cell lines to verify Wnt1’s effect on
tumor progression and its association with canonical Wnt signaling.
Materials and Methods
Wnt1 overexpression plasmid (pcDNA3.1- Wnt1) and empty
vector were obtained from Addgene (Cambridge, MA, USA). Wnt1 siRNA (si- Wnt1) and
negative control siRNA (si-NC) were purchased from Thermo Fisher Scientific
(Waltham, MA, USA). HCT116 cells (5×10⁵ cells/well) were seeded in 6-well
plates and transfected with plasmids or siRNA using Lipofectamine 3000
(Invitrogen, Carlsbad, CA, USA) at 60-70% confluency. Wnt1 expression was
verified by Western blot and qRT-PCR 48h post-transfection.
Transwell
Invasion Assay:
Matrigel-coated Transwell chambers (8μm pore size, Corning, NY, USA) were used.
Transfected cells (2×10⁴ cells/well) in serum-free medium were added to the
upper chamber; medium with 20% FBS was added to the lower chamber. Invasive
cells were counted at 24h.
Sphere
Formation Assay: Cells
(1×10³ cells/well) were seeded in ultra-low attachment 6-well plates with stem
cell medium (DMEM/F12 + 20 ng/mL EGF + 20 ng/mL bFGF + 1× B27). Spheres (>50
μm) were counted after 7 days.
Results
Wnt1 is upregulated in CRC Cell Lines
qRT-PCR results showed Wnt1 mRNA expression in HCT116 and SW480
cells was 0.31±0.04 and 0.38±0.05 folds of that in NCM460 cells, respectively
(P<0.01). Western blot analysis revealed Wnt1 protein relative gray values
in HCT116 (0.34±0.04) and SW480 (0.41±0.05) cells were significantly lower than
that in NCM460 cells (1.00±0.11, P<0.01).
Wnt1 Inhibits CRC Cell Proliferation
Wnt1 overexpression reduced HCT116 cell OD450 at 48h (0.62±0.07
vs. 0.96±0.09, P<0.05) and 72h (0.69±0.07 vs. 1.35±0.12, P<0.05). Wnt1
knockdown increased OD450 at 48h (1.15±0.10 vs. 0.93±0.08, P<0.05) and 72h
(1.46±0.13 vs. 1.31±0.11, P<0.05).
Wnt1 Suppresses CRC Cell Migration and Invasion
Wnt1 overexpression increased HCT116 cell migration rate to
76.2±6.3% (vs. 47.8±4.8% in control, P<0.01) and invasive cell number to
145±12 (vs. 63±7 in control, P<0.01). Wnt1 knockdown reduced migration rate
to 40.2±4.7% (vs. 77.5±6.4% in si-NC, P<0.01) and invasive cell number to
57±6 (vs. 148±12 in si-NC, P<0.01).
Wnt1 Maintains CRC Cell Stemness
Wnt1 overexpression increased HCT116 cell sphere formation
efficiency to 3.2±0.3 folds of control (P<0.01) and upregulated CD133
(2.35±0.22 vs. 1.00±0.09, P<0.05). Wnt1 knockdown reduced sphere formation
efficiency to 0.42±0.10 folds of si-NC (P<0.01) and downregulated CD133
(0.45±0.04 vs. 1.00±0.09, P<0.05).
Wnt1 Activates Canonical Wnt/β-Catenin Signaling
Wnt1 overexpression increased nuclear active β-catenin (2.75±0.25
vs. 1.00±0.09, P<0.05), Cyclin D1 (2.42±0.23 vs. 1.00±0.08, P<0.05) and
reduced cytoplasmic β-catenin (0.40±0.04 vs. 1.00±0.08, P<0.05). Wnt1
knockdown showed opposite effects: nuclear active β-catenin and Cyclin D1
decreased (P<0.05), while cytoplasmic β-catenin accumulated (P<0.05).
β-Catenin inhibitor (XAV939) reversed Wnt1-induced proliferation and stemness
(P<0.05).
Discussion
This study confirms Wnt1 is upregulated in CRC cells and its
overexpression promotes proliferation, migration, invasion and stemness by
activating canonical Wnt/β-catenin signaling-consistent with its oncogenic role
in gastric and pancreatic cancer7,8. Mechanistically, Wnt1 binds to FZD-LRP5/6 complexes, inhibits
GSK-3β-mediated β-catenin degradation, promotes nuclear translocation of
β-catenin and drives transcription of cell cycle regulators (e.g., Cyclin D1)
and CSC markers (e.g., CD133)4, which enhances CRC’s malignant potential. Limitations include
lack of in vivo validation; future studies should explore Wnt1’s crosstalk with
the PI3K-AKT pathway in CRC9, as both pathways frequently co-activate to promote tumor
progression. Targeting Wnt1 (e.g., via neutralizing antibodies or
small-molecule inhibitors of Wnt1-FZD interaction) may be a promising strategy
for CRC treatment10.
Conclusion
Wnt1 is upregulated in colorectal cancer cell lines and promotes
CRC progression by activating canonical Wnt/β-catenin signaling and regulating
stemness/pro-metastatic genes, highlighting its potential as a therapeutic
target for CRC.