Induction of apoptosis in cancer cells by tumor necrosis factor and butyrolactone, an inhibitor of cyclin-dependent kinases

Abstract

Induction of apoptosis by tumor necrosis factor (TNF) is modulated by changes in the expression and activity of several cell cycle regulatory proteins. We examined the effects of TNF (1-100 ng/ml) and butyrolactone I (100 µM), a specific inhibitor of cyclin-dependent kinases (CDK) with high selectivity for CDK-1 and CDK-2, on three different cancer cell lines: WEHI, L929 and HeLa S3. Both compounds blocked cell growth, but only TNF induced the common events of apoptosis, i.e., chromatin condensation and ladder pattern of DNA fragmentation in these cell lines. The TNF-induced apoptosis events were increased in the presence of butyrolactone. In vitro phosphorylation assays for exogenous histone H1 and endogenous retinoblastoma protein (pRb) in the total cell lysates showed that treatment with both TNF and butyrolactone inhibited the histone H1 kinase (WEHI, L929 and HeLa) and pRb kinase (WEHI) activities of CDKs, as compared with the controls. The role of proteases in the TNF and butyrolactoneinduced apoptosis was evaluated by comparing the number and expression of polypeptides in the cell lysates by gel electrophoresis. TNF and butyrolactone treatment caused the disappearance of several cellular protein bands in the region between 40-200 kDa, and the 110-90-and 50-kDa proteins were identified as the major substrates, whose degradation was remarkably increased by the treatments. Interestingly, the loss of several cellular protein bands was associated with the marked accumulation of two proteins apparently of 60 and 70 kDa, which may be cleavage products of one or more proteins. These findings link the decrease of cyclin-dependent kinase activities to the increase of protease activities within the growth arrest and apoptosis pathways induced by TNF. Correspondence

PLGA Microspheres Coated with Cancer Cell-Derived Vesicles for Improved Internalization into Antigen-Presenting Cells and Immune Stimulation

“…This result was also confirmed by gel electrophoresis (Figure C, inset). A strong band of nucleic acid, e.g., chromosomal DNA, was observed in A549 cell lysate, while no noticeable nucleic acid band was observed in VEs. , …”

“…A strong band of nucleic acid, e.g., chromosomal DNA, was observed in A549 cell lysate, while no noticeable nucleic acid band was observed in VEs. 26,27 To covalently immobilize VEs onto MS for stable attachment of VE onto MS surface, the surfaces of MS were modified with alkyne groups via a carbodiimide coupling reaction, as previously described. 28 It is conceivable that covalent attachment of VE on MS could allow stable surface modification in the presence of serum proteins compared to noncovalent modification via ionic interactions, which might be proper for in vivo application.…”

Prominent induction of cyclin B1 in G2/M renal cancer cells with butyrolactone 1

“…Another paper reported that tumor necrosis factor (TNF) induced apoptosis in cancer cell lines of WEHI, L929 and HeLa S3, but 100 µmol/L BL did not. Although BL increased the induction of apoptosis by TNF, it was thought to block cell growth via different mechanisms from apoptosis 26 …”