Effects of the histone deacetylase inhibitor trichostatin A on nuclear texture and c-jun gene expression in drug-sensitive and drug-resistant human H69 lung carcinoma cells.
BACKGROUND
Texture analysis of chromatin patterns by image cytometry can be used in the development and refinement of diagnosis and prognosis of cancers and in the follow-up of therapies. However, little is known about the biological mechanisms underlying these patterns. Epigenetic mechanisms as histone posttranslational modifications and particularly histone acetylation could play a major role in the determination of these chromatin patterns and then influence nuclear texture measurements.


METHODS
This study examined the consequences of treatment by the histone deacetylase inhibitor trichostatin A (TSA) on the nuclear texture in human cell lines sensitive and resistant to chemotherapy. Small cell lung carcinoma H69 cells and their variant H69-VP, which is resistant to etoposide, were incubated with 100 ng/ml of TSA for 0 to 24 h. Nuclear texture was evaluated by image cytometry and compared with the histone H4 acetylation level measured by western blotting and expression of c-jun gene evaluated by reverse transcription and real-time polymerase chain reaction.


RESULTS
TSA treatment induced an increase in histone H4 acetylation level in both cell lines. However, at the level of chromatin texture, sensitive H69 cells displayed a progressive chromatin decondensation up to 24 h, whereas resistant H69-VP showed rapid (8 h) but transient changes. Similarly, expression of c-jun increased regularly in TSA-treated H69 cells. In H69-VP cells, an increase was also observed up to 12 h followed by a decrease after 24 h of treatment.


CONCLUSIONS
Analysis of nuclear texture appeared to be a sensitive technique to detect chromatin pattern alterations induced by the histone deacetylase inhibitor TSA in the H69 cell line and enabled the observation of chromatin pattern discrepancies between chemotherapeutic drug-sensitive and drug-resistant cells during this treatment. When c-jun gene expression was analyzed as gene sensitive to epigenetic control, these textural differences seemed to be correlated to gene expression.
El-Khoury
Victoria
V
Unité MéDIAN-CNRS UMR 6142, IFR 53, Faculté de Pharmacie, Reims, France.
Gomez
Dennis
D
Liautaud-Roger
Françoise
F
Trussardi-Régnier
Aurélie
A
Dufer
Jean
J
D018288:Carcinoma, Small Cell / Q000235:genetics; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002843:Chromatin / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D044127:Epigenesis, Genetic; D015870:Gene Expression / Q000187:drug effects; D016758:Genes, jun / Q000187:drug effects*; D006655:Histone Deacetylases / Q000187:drug effects; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D019044:Image Cytometry; D015151:Immunoblotting; D008175:Lung Neoplasms / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002843:Chromatin; D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; C012589:trichostatin A; D006655:Histone Deacetylases