Figure 1.
CDH17 expression in a panel of gastric cancer cell lines and in gastric cancer tissue microarray.
(A) Thirty gastric cell lines are lysed and subjected to Western blot analysis (left). All tested cells are categorized into 4 expression level of CDH17, High, Median (Medi), Low, Not detected (ND), based on optical density analysis against beta-actin (right); (B) Representative IHC pictures from patient 1 (well-differentiated gastric cancerous tissue), patient 2 (poorly differentiated gastric cancerous tissue) and patient 3 (adjacent normal tissue); CDH17 showed clear membrane location in tumor or adjacent tissues; (C) Representative IHC pictures of positive CDH17 stain with scoring from + to +++.
Table 1.
Tissue microarray analysis of CDH17 and clinical pathological characteristics in Chinese gastric cancers.
Figure 2.
Suppression of in vitro cell proliferation and colony formation by CDH17 siRNA.
(A) The siRNA knock-down efficiency was confirmed by Western blotting 48 h post transfection with 20 nM siCDH17 or scramble siRNA; (B) Proliferation assay. The cells were transfected with 20 nM siCDH17 or scramble siRNA in 10 cm dishes. 48 h later, the cells were suspended and reseeded into 96-well plates. The cell viability was assayed with CCK-8 cell proliferation kit 72 h post seeding. The experiment was carried out in triplicate, and the data were presented as mean ± standard deviation; (C) Colony formation assay. The cells were transfected with siCDH17 as proliferation assay and reseeded into 6-well plates. The colonies were counted under microscope after stained with MTT 14 days post seeding. The experiment was carried out in triplicate and the typical images were shown. The data were presented as mean ± standard deviation.
Figure 3.
Knockdown of CDH17 in AGS cells inhibited cell proliferation, migration, adhesion, colony formation and induced a cell-cycle arrest and apoptosis.
Different assay were described in materials and methods. (A) Real-time PCR analysis showed the knock down of CDH17 at the mRNA level in AGS cells (C), AGS cells transiently transfected with pcDNATM6.2-GW/EmGFP-scramble miR plasmid (NC) and pcDNATM6.2-GW/EmGFP-CDH17 miR plasmids (90-1, 90-2, 90-3, and 90-4); (B) Western blotting for the effect of CDH17 knockdown using different concentrations of Tet for 48 h in TR-AGS-CDH17_KD cells; (C) Cell proliferation, migration (6 days post treatment), adhesion (6 days post treatment. **P<0.01) and colony formation in soft agar (7 days post treatment. **P<0.01); (D) Proliferation rescue assay. TR-inducible AGS-CDH17_KD stable cells were seeded in 60 mm ×15 mm dish and cultured for 10 days with or without 5.0 µg/ml Tet. For rescue group, the culture medium containing Tet was replaced by fresh medium on day 4, and cells were continued to be cultured to day 10. Cells in each group were harvested on day 2, 4, 6, 8 and 10 for cell number counting (left) and Western blotting analysis (right); (E) Cell cycle analysis after cells were treated with 5.0 µg/ml Tet for 6 days; and (F) Cell apoptosis analysis after cells were treated with 5.0 µg/ml Tet for 6 days by flow cytometry.
Figure 4.
Overexpression of CDH17 in MGC-803 cells promoted tumor growth in nude mice.
(A) Western blotting showed the induction efficiency of CDH17 overexpression; (B) Tumor growth in nude mice. When tumor volume reached ∼100 mm3, the drinking water was replaced with 2.5% sucrose containing 0.2 mg/ml Tet or not. *P<0.05, Tet-on group vs Tet-free group; (C) Western blotting analysis of xenograft tumor tissues.
Figure 5.
Knockdown CDH17 in AGS cells induced alteration of related proteins.
TR-AGS-CDH17_KD stable cells were treated or untreated with 5 µg/ml Tet for 5 days. (A) Antibody array assay. (a) Human Apoptosis Array Kit, (b) Human Phospho-Kinase Array Kit, (c) Human Soluble Receptor Array Kit Non-Hematopoietic Pane; (B) Changing ratio of related proteins between Tet-on and Tet-free cells; (C) Changes of related proteins found in antibody array assay were confirmed using Western blotting analysis.
Figure 6.
Schematic diagram of the regulatory and signaling network of CDH17 in GC.
This schematic diagram demonstrates the inducing effect of CDH17 on Ras/Raf/MEK/ERK signaling pathway and illustrates the hypothetic involvement of integrins in GC. CDH17 indirectly affects integrins to stabilize their structure and activity. The up-regulation of cadherin-integrin signaling activates the Ras/Raf/MEK/ERK pathway. The activation of ERK regulates various nuclear and cytoplasmic substrates, including p53 and p21, which involve in diverse cellular responses, such as cell proliferation, migration, adhesion, colony formation, cell-cycle and apoptosis.