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Involvement of p53 in specific anti-neuroectodermal tumor activity of aloe-emodin
Teresa Pecere1, Federica Sarinella, Cristiano Salata
1Department of Histology, Microbiology and Medical Biotechnology, University of Padova, Padua, Italy.
Abstract:
Previously, we have identified aloe-emodin (AE) as a new type of anticancer agent, with activity that is based on apoptotic cell death promoted by a neuroectodermal tumor-specific drug uptake. We attempt to clarify the intracellular target of AE and the apoptosis-signaling pathway activated by AE in neuroblastoma cell lines. Two-photon excitation microscopy and spectroscopic titrations documented that AE is highly concentrated in susceptible cells and binds to DNA. One of the most important mediators of apoptotic response to genotoxic stimuli, such as anticancer agents, is the p53 tumor suppressor gene. To evaluate the role played by p53 in AE-induced apoptosis a p53 mutant cell line, which lacks transcriptional activity of p53 targeted genes, was tested. AE displayed a reduced growth inhibitory and pro-apoptotic activity in p53 mutant cells (SK-N-BE(2c)) with respect to the p53 wild-type line (SJ-N-KP). This effect was not caused by a reduced drug uptake in the mutant neuroblastoma cell line but was related to a different apoptotic cell phenotype. Whereas SJ-N-KP cells were susceptible to a p53 transcription-dependent pathway of apoptosis, SK-N-BE(2c) cells underwent apoptosis with up-regulation of p53 expression but not of p53-target genes. After AE treatment p53 translocates to the mitochondria inter-membrane space in both neuroblastoma cell lines. Due to its high accumulation in neuroectodermal tumor cells AE could also kill tumor cells harboring p53 mutant genes. This property would further contribute to AE specific anti-tumor activity and might be exploitable in the clinic.
Insights
Aloe-emodin (AE) anticancer activity relies on DNA binding and apoptosis induction in neuroblastoma cells. Its efficacy is partly p53-dependent, but AE can also kill p53-mutant tumor cells, suggesting broad clinical potential.
Area of Science:
- Pharmacology
- Molecular Biology
- Oncology
Background:
- Aloe-emodin (AE) is a novel anticancer agent targeting neuroectodermal tumors.
- AE induces apoptotic cell death via tumor-specific drug uptake.
- The intracellular targets and apoptosis pathways of AE require further elucidation.
Purpose of the Study:
- To identify the intracellular target of AE.
- To delineate the apoptosis-signaling pathway activated by AE in neuroblastoma.
- To evaluate the role of the p53 tumor suppressor gene in AE-induced apoptosis.
Main Methods:
- Two-photon excitation microscopy and spectroscopic titrations to assess AE localization and DNA binding.
- Utilized p53 wild-type and mutant neuroblastoma cell lines (SJ-N-KP and SK-N-BE(2c)).
- Analyzed p53 transcriptional activity, gene expression, and protein translocation.
Main Results:
- AE concentrates in susceptible cells and binds to DNA.
- AE exhibited reduced growth inhibition and apoptosis in p53 mutant cells.
- Apoptosis in p53 wild-type cells was p53 transcription-dependent, while mutant cells showed p53 upregulation without target gene activation.
- p53 translocated to mitochondria in both cell lines post-AE treatment.
Conclusions:
- AE's anticancer activity involves DNA binding and p53-mediated apoptosis.
- AE can induce apoptosis in neuroblastoma cells irrespective of p53 status.
- AE's tumor-specific accumulation and ability to target p53-mutant cells highlight its potential for clinical application in neuroectodermal tumors.