Mountain View
biomedical and healthCAre Data Discovery Index Ecosystem
help Advanced Search
Title: Induction of Senescence in Diterpene Ester-Treated Melanoma Cells via PKC-dependent Hyperactivation of the MAPK Pathway      
dateReleased:
07-01-2010
description:
The diterpene ester PEP005 is a novel anticancer agent that activates PKC and cures subcutaneous murine melanoma by topical application. We now describe the in vitro cytostatic effects of PEP005 and the diterpene ester TPA, observed in 20% of human melanoma cell lines. Primary cultures of normal human neonatal fibroblasts were uniformly resistant to growth arrest, indicating a potential for tumor selectivity. Sensitive cells were induced to senesce and exhibited a G1 and G2/M arrest. There was sustained expression of p21WAF1/CIP1, irreversible dephosphorylation of the retinoblastoma gene product (Rb) and transcriptional silencing of E2F-responsive genes in sensitive cell lines. Activation of MEK1/2 by PKC was required for diterpene ester-induced senescence. Expression profiling revealed that the MAPK inhibitor HREV107 was expressed at a higher transcript level in resistant compared to sensitive cell lines. We propose that activation of PKC over-stimulates the Ras/Raf/MEK/ERK pathway, resulting in sustained induction of p21WAF1/CIP1, dephosphorylation of Rb and transcriptional silencing of E2F-responsive genes required for DNA synthesis and mitosis. To investigate the molecular changes associated with the senescent phenotype, we examined the unique transcriptional changes occurring in sensitive melanoma cell lines treated with TPA or PEP005. Initially a time-course cDNA microarray analysis was conducted on one sensitive and one resistant cell line treated with 1 µg/ml of TPA for 6, 24 h and 24 h recovery following 24 h treatment, to determine the earliest time point at which the most significant changes in transcription occurred. The results provided support for conducting array experiments with 24 h treatment, in which three sensitive and four resistant melanoma cell lines were treated with 1 µg/ml of either diterpene ester. Our primary objective was to identify those genes which were uniquely up or down-regulated in sensitive or resistant cell lines in response to treatment, which could reflect the phenotypic outcome. Through applying a series of stringent selective criteria (see Material and Methods) we found that the most significant changes occurred in the transcriptional repression of genes required for DNA synthesis and mitosis in cell lines sensitive to treatment (Table 1). To confirm that these changes were reflected at the protein level, western blot analysis was conducted on three sensitive and three resistant cell lines following 6 and 24 h treatment with TPA or PEP005. We also included a 24 h recovery time point to determine the irreversibility of the change.
privacy:
not applicable
aggregation:
instance of dataset
ID:
E-GEOD-3484
refinement:
raw
alternateIdentifiers:
3484
dateSubmitted:
10-19-2005
keywords:
functional genomics
dateModified:
03-27-2012
availability:
available
types:
gene expression
name:
Homo sapiens
ID:
A-GEOD-2992
name:
QIMR Human 4.5k v30
accessURL: https://www.ebi.ac.uk/arrayexpress/files/E-GEOD-3484/E-GEOD-3484.raw.1.zip
storedIn:
ArrayExpress
qualifier:
gzip compressed
format:
TXT
accessType:
download
authentication:
none
authorization:
none
accessURL: https://www.ebi.ac.uk/arrayexpress/files/E-GEOD-3484/E-GEOD-3484.processed.1.zip
storedIn:
ArrayExpress
qualifier:
gzip compressed
format:
TXT
accessType:
download
authentication:
none
authorization:
none
accessURL: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE3484
storedIn:
Gene Expression Omnibus
qualifier:
not compressed
format:
HTML
accessType:
landing page
primary:
true
authentication:
none
authorization:
none
abbreviation:
EBI
homePage: http://www.ebi.ac.uk/
ID:
SCR:004727
name:
European Bioinformatics Institute
homePage: https://www.ebi.ac.uk/arrayexpress/
ID:
SCR:002964
name:
ArrayExpress

Feedback?

If you are having problems using our tools, or if you would just like to send us some feedback, please post your questions on GitHub.