The effect of valproic acid (VA) on protein expression in human T-lymphocytic leukemia cells MOLT-4 was studied. VA is an inhibitor of histonedeacetylases and has a potential use as antitumor agent in leukemia treatment. The authors in this work prove that 4 h long incubation with 2 mmol/l VA causes phosphorylation of histone H2A.X and its colocalization with 53BP1 in nuclear foci. Their co-localization is typical for DSB signaling machinery. These foci were detected in cells after 4 h exposure without increase of Annexin V positive apoptotic cells. Slight increase in apoptosis (Annexin V positivity) after 24 h is accompanied by more intensive increase in phosphorylation of H2A.X and also by formation of nuclear foci containing gammaH2A.X and 53BP1. Treatment of cells with 2 mmol/l VA resulted in induction of apoptosis affecting about 30% of cells after incubation for 72 h. The changes in protein expression were examined after cell incubation with 2 mmol/l VA for 4 h. Proteins were separated by two-dimensional electrophoresis and quantified using image evaluation system. Those exhibiting significant VA-induced abundance alterations were identified by mass spectrometry. Changes in expression of 22 proteins were detected, of which 15 proteins were down-regulated. Proteomic analysis resulted in successful identification of three proteins involving alfa-tubulin 3, tubulin-specific chaperone and heterogeneous nuclear ribonucloprotein F. Expression of seven proteins was up-regulated, including heterogeneous nuclear ribonucloprotein A/B. Identified proteins are related to microtubular system and hnRNP family. Suppression of microtubular proteins and changes of balance among hnRNPs can contribute to proliferation arrest and apoptosis induction.

• MeSH
• Electrophoresis, Gel, Two-Dimensional MeSH
• Annexin A5 metabolism   MeSH
• Apoptosis drug effects   MeSH
• Heterogeneous-Nuclear Ribonucleoproteins metabolism   MeSH
• Enzyme Inhibitors pharmacology   MeSH
• Histone Deacetylase Inhibitors MeSH
• Valproic Acid pharmacology   MeSH
• Leukemia, T-Cell drug therapy   metabolism   pathology   MeSH
• Humans MeSH
• Neoplasm Proteins metabolism   MeSH
• Proteome analysis   MeSH
• Flow Cytometry MeSH
• Signal Transduction MeSH
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization MeSH
• Cell Survival drug effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Annexin A5 MeSH
• Heterogeneous-Nuclear Ribonucleoproteins MeSH
• Enzyme Inhibitors MeSH
• Histone Deacetylase Inhibitors MeSH
• Valproic Acid MeSH
• Neoplasm Proteins MeSH
• Proteome MeSH