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Effects of the Notch1 signaling pathway on human lung cancer A549 cells
Yun Zeng1,2, Bijian Yin1, Xinwei Wang1
1a Department of Medical Oncology , Jiangsu Cancer Hospital , Nanjing , Jiangsu Province , China.
Purpose:
To evaluate the effects of the Notch1 signaling pathway on human lung cancer A549 cells.
Materials And Methods:
A549 cells were transfected with recombinant plasmids. Cell proliferation was detected by MTT assay. A tumor-bearing mouse model was established for intratumoral gene injection. Apoptosis-related factors were detected by immunohistochemical assay. Caspase-8, caspase-3, caspase-9, PI3K, pAkt and pSTAT3 expressions were detected by Western blotting.
Results:
Compared with A549-GFP and A549 cells, A549-ICN cell growth in mice decelerated, tumor volume significantly reduced (p < 0.01), and survival time significantly increased (p < 0.05). Cyclin E and phosphorylated Rb protein expressions were significantly down-regulated. Compared with control, apoptosis-related protein Bcl-2 expression in tumors injected with Notch1 gene was significantly inhibited. After Deltex1 transfection, A549 cell proliferation decelerated, growth was significantly inhibited (p < 0.05), and survival time was significantly extended (p < 0.05). Cyclin E and mutant p53 protein expressions in tumors were down-regulated, phosphorylated Rb expression was almost completely inhibited, and Bcl-2 expression was significantly inhibited. TNF-α-related apoptosis-inducing ligand (TRAIL) inhibited A549-ICN cell growth time- and dose-dependently. After treatment for 24 h or longer, TRAIL induced apoptosis of more A549-ICN cells. Cleaved caspase-3 and cleaved caspase-9 were detected only in A549-ICN cells after 6 h of 40 ng/mL TRAIL treatment, but cleaved caspase-8 was not detected. Combining Notch1 signal with TRAIL inhibited PI3K, phosphorylated Akt and phosphorylated STAT3 expressions.
Conclusion:
The Notch1 signaling pathway may inhibit A549 cell growth in vitro and in vivo by regulating cell cycle-related and anti-apoptotic protein expressions. Notch1 activation also suppressed A549 cell apoptosis by inhibiting the PI3K/pAkt pathway and activating the caspase-3 pathway in cooperation with TRAIL.
Insights
The Notch1 signaling pathway inhibits human lung cancer A549 cell growth and promotes apoptosis. Activating Notch1 signaling, combined with TRAIL, suppresses tumor growth by inhibiting key cell survival pathways.
Area of Science:
- Molecular Biology
- Oncology
- Cell Signaling
Background:
- The Notch1 signaling pathway plays a crucial role in cell differentiation, proliferation, and apoptosis.
- Dysregulation of Notch1 signaling is implicated in the development and progression of various cancers, including lung cancer.
- Understanding the specific mechanisms by which Notch1 affects lung cancer cells is essential for developing targeted therapies.
Purpose of the Study:
- To investigate the impact of the Notch1 signaling pathway on the proliferation and apoptosis of human lung cancer A549 cells.
- To elucidate the molecular mechanisms underlying Notch1's effects on A549 cells in vitro and in vivo.
Main Methods:
- A549 cells were transfected with recombinant plasmids to modulate Notch1 signaling.
- Cell proliferation was assessed using MTT assays.
- A tumor-bearing mouse model was utilized for in vivo studies, with gene delivery via intratumoral injection.
- Apoptosis-related factors, caspase expressions (caspase-8, -3, -9), and signaling proteins (PI3K, pAkt, pSTAT3) were analyzed using immunohistochemical and Western blotting assays.
Main Results:
- Activation of Notch1 signaling (A549-ICN cells) significantly inhibited A549 cell growth, reduced tumor volume, and prolonged survival in mice.
- Notch1 activation led to down-regulation of cell cycle regulators (Cyclin E, phosphorylated Rb) and inhibited anti-apoptotic protein (Bcl-2) expression.
- Combined treatment with Notch1 activation and TRAIL synergistically inhibited tumor growth and suppressed key survival pathways, including PI3K/Akt and STAT3.
Conclusions:
- The Notch1 signaling pathway exerts an inhibitory effect on human lung cancer A549 cell growth both in vitro and in vivo.
- Notch1 regulates cell cycle progression and apoptosis by modulating the expression of key regulatory proteins.
- Notch1 activation, in conjunction with TRAIL, effectively suppresses lung cancer progression by inhibiting PI3K/Akt and activating caspase-3 pathways.
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